Omipalisib (GSK458), a Dual an-PI3K/mTOR Inhibitor, Exhibits in Vitro and In Vivo activity in Chemotherapy-Sensitive and -Resistant Models of Burkitt Lymphoma

Abstract Background: Reports of recurrent genomic alterations in Burkitt lymphoma (BL) have identified multiple recurrent alterations that result in activation of PI3K highlighting the importance of the PI3K/AKT/mTOR pathway in Burkitt lymphomagenesis. In a cell line model of resistant BL, we have previously identified an increase of PI3K/AKT/mTOR pathway activation suggesting a role in therapy resistance. While inhibition of PI3K-delta using the isoform specific inhibitor idelalisib has demonstrated clinical activity in indolent lymphomas, limited single agent activity has been observed in more aggressive variants. Pre-clinical investigation of idelalisib in BL indicated similar somewhat limited in vitro activity with synergistic activity in combination with chemotherapy. Broader inhibition of both upstream PI3K and downstream mTOR may exhibit more significant anti-lymphoma activity. Objectives: Investigate the in vitro and in vivo activity of the dual pan-PI3K/mTOR inhibitor omipalisib (GSK458) in chemotherapy-sensitive and -resistant BL cell line models. Methods: Experiments were conducted in Raji, Raji 4RH (chemotherapy-rituximab resistant), Ramos, and Daudi BL cells. Cell viability following exposure to omipalisib +/- chemotherapy was analyzed using Cell-Titer Glo and Alamar blu assays. Induction of apoptosis was assessed by flow cytometry for Annexin V (AV)-propidium iodide (PI) staining. Downstream effects of omipalisib on PI3K/Akt/mTOR signaling were analyzed using western blotting. Cell cycle analysis was performed by flow cytometry using PI staining. Synergy of combination exposures was determined by calculation of the combination index (CI) using CalcuSyn software. In vivo activity was evaluated using disseminated Raji and subcutaneous Ramos SCID mouse xenograft models. The survival end point was hind limb paralysis in the disseminated model and tumor diameter >2cm in the subcutaneous model. Mice were treated with vehicle or omipalisib daily by oral gavage. Median survival was compared by Kaplan-Meier analysis. Results: Exposure of BL cells to omipalisib for 24-72 hours resulted in a dose- and time-dependent decrease in viable cells at nM concentrations (48h IC50 values: Raji=1.2uM, Raji 4RH=0.02uM, Ramos=0.01uM, Daudi=0.01uM) (Figure 1A). Marked induction of apoptosis occurred following 72h exposure to omipalisib primarily in chemosensitive cells with half-maximal effect noted at approximately 200nM, but requiring significantly higher concentrations to induce apoptosis in therapy resistant Raji 4RH cells (%AV positive at 200nM: Raji=40.7%, Raji 4RH=4.4%, Ramos=59.4% and Daudi=46.9%). Downstream of PI3K/Akt/mTOR, S6 and GSK3β showed reduced phosphorylation after 30 minute omipalisib exposure. G1 cell cycle arrest occurred in all cell lines following exposure to omipalisib for 72 hours; however, chemotherapy-resistant Raji 4RH cells arrested in G2/M at higher concentrations. BL cells exposed to omipalisib in combination with either doxorubicin or dexamethasone, exhibited synergistic anti-tumor activity (CI<0.9) with synergistic induction of apoptosis in therapy sensitive cells exposed to omipalisib and chemotherapy. NOD-SCID mice injected via tail vein with Raji-luc (provided by Dr. Mitchell Cairo) and treated with omipalisib demonstrated decreased luciferase signal compared to controls (Figure 1C) while mice with established subcutaneous Ramos xenografted tumors treated with omipalisib exhibited slower tumor progression compared to controls (Figure 1B), though with only modest prolongation of survival (median 28 vs 34 days, n=15/group, p<0.05). Conclusion: Dual PI3K-mTOR inhibitor omipalisib suppresses the PI3K/Akt/mTOR pathway leading to induction of apoptosis, impaired BL cell proliferation in vitro and in vivo and exhibits synergistic in vitro activity when combined with cytotoxic chemotherapy highlighting the relevance of PI3K/Akt/mTOR pathway inhibition as a potential therapeutic option in BL. Disclosures No relevant conflicts of interest to declare.

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PI3K/Akt/mTOR Pathway Inhibition in Chemotherapy-Sensitive and -Resistant Models of Burkitt Lymphoma

Blood ◽

10.1182/blood.v126.23.1558.1558 ◽

2015 ◽

Vol 126 (23) ◽

pp. 1558-1558 ◽

Cited By ~ 1

Author(s):

Maria Bhatti ◽

Thomas Ippolito ◽

Cory Mavis ◽

Matthew J. Barth

Keyword(s):

Cell Cycle ◽

Flow Cytometry ◽

Cell Viability ◽

Cell Line ◽

Cell Lines ◽

Propidium Iodide ◽

Mtor Pathway ◽

Propidium Iodide Staining ◽

Induction Of Apoptosis ◽

Pre Treatment

Abstract Introduction: Burkitt lymphoma (BL) is the most common form of B-cell non-Hodgkin lymphoma (B-NHL) in children. Despite significant improvements in survival with de novo disease, treatment of relapsed or refractory BL remains a significant hurdle with survival in only about 20% of patients. Novel therapeutic approaches are necessary to improve outcomes in this group of childhood B-NHL patients with the worst prognosis. Recent literature has identified a high rate of recurrent mutations that result in activation of the PI3K/Akt pathway in BL and have implicated activation of PI3K/Akt in coordination with Myc in BL lymphomagenesis. Our laboratory has developed rituximab and chemotherapy resistant cell line models and subsequently found that these cell lines exhibit increased activation of Akt. We hypothesized that increased activation of Akt may be contributing to chemoresistance and that targeting the PI3K/Akt/mTOR pathway may increase chemoresponsiveness. To that end, we have investigated the effect of inhibiting the PI3K/Akt/mTOR pathway with either the PI3K-delta inhibitor idelalisib or the pan-PI3K/mTOR inhibitor BEZ-235 in cell line models of BL. Methods: The in vitro effect of idelalisib or BEZ-235 was investigated in BL cell lines including Raji, Raji 2R and Raji 4RH (rituximab-chemotherapy resistant), Raji 7R and Raji 8RH (rituximab resistant), Ramos and Daudi. Cell viability following inhibitor exposure was assessed by Alamar blu and cell-titer glo assays. The effect of inhibitor exposure on cell cycle progression was determined by flow cytometry using propidium iodide staining. Inhibition of Akt activation following inhibitor exposure was determined using phospho-flow cytometry. The activity of cytotoxic chemotherapeutic agents following inhibition by idelalisib or BEZ-235 was assessed using Alamar blu and cell titer glo assays. Results: In vitro exposure of BL cell lines to idelalisib in concentrations from 0.1-100µM for 24, 48 or 72 hours resulted in a dose and time-dependent decrease in viable cells in all cell lines tested with IC50 concentrations of 60-300uM. Pre-treatment with the pan-caspase inhibitor QVD resulted in a small reversal in the decrease in cell viability suggesting only a minimal portion of the activity was caspase dependent. When induction of apoptosis was measured using annexin V-propidium iodide staining, little induction of apoptosis was observed with single agent idelalisib at concentrations up to 100uM. Determination of cell cycle progression following exposure to idelalisib at 1, 10, 50 or 100 uM for 24, 48 or 72 hours indicated a time and dose dependent cell cycle arrest in all cell lines. In chemotherapy-sensitive cell lines the arrest was primarily noted in G1, while the chemotherapy-resistant Raji 2R and Raji 4RH cell lines exhibited arrest primarily in G2/M. A significant reduction in cell viability following chemotherapy exposure for 48 hours was noted in chemotherapy resistant Raji 2R cells following pre-treatment for 48 hours with idelalisib 10uM compared to non-idelalisib exposed cells (doxorubicin 10uM 55% vs 77%, p<0.001; vincristine 0.05uM, 48% vs 61%, P<0.001). At higher idelalisib pre-treatment concentrations (50uM) additional synergistic activity was observed in Raji 2R cells (cisplatin 48% vs 61%, p<0.001; dexamethasone 67% vs 87%, p<0.01). To further assess the effect of dual inhibition of PI3K and mTOR, cell lines were exposed to the dual inhibitor BEZ-235. BEZ-235 exhibited a more potent decrease in cell viability compared to idelalisib with activity at nM concentrations. Unlike idelalisib, exposure to BEZ-235 resulted in significant induction of apoptosis by Annexin V-propidium iodide staining. BEZ-235 also exhibited synergistic activity in combination with chemotherapy in all cell lines. At equivalent dosing, BEZ-235 exposure resulted in a more significant decrease in Akt phosphorylation compared to idelalisib as determined by flow cytometry for p-Akt at Ser and Thr phosphorylation sites. Conclusions: Chemotherapy sensitive and resistant BL cell line models are susceptible to inhibition of the PI3K/Akt/mTOR pathway. Targeted inhibition of this pathway leads to a decrease in AKT activation, decrease in cell viability, cell cycle arrest and an increase in sensitivity to cytotoxic chemotherapeutic agents. Broader inhibition of both PI3K and mTOR is more effective than more targeted inhibition of PI3K-delta alone. Disclosures No relevant conflicts of interest to declare.

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Omipalisib (GSK458), a Novel Pan-PI3K/mTOR Inhibitor, Exhibits In Vitro Anti-Lymphoma Activity in Chemotherapy-Sensitive and -Resistant Models of Burkitt Lymphoma

Blood ◽

10.1182/blood.v128.22.5376.5376 ◽

2016 ◽

Vol 128 (22) ◽

pp. 5376-5376 ◽

Cited By ~ 2

Author(s):

Thomas Ippolito ◽

Greg Tang ◽

Cory Mavis ◽

Juan J Gu ◽

Francisco J. Hernandez-Ilizaliturri ◽

...

Keyword(s):

Cell Cycle ◽

Flow Cytometry ◽

Cell Line ◽

Cell Lines ◽

Western Blotting ◽

Propidium Iodide ◽

Annexin V ◽

Mtor Pathway ◽

Pathway Inhibition

Abstract Background: Despite significant gains achieved in the treatment of Burkitt lymphoma (BL), current multi-agent immunochemotherapeutic regimens lead to high rates of acute toxicity, and relapsed/refractory disease still represents a significant hurdle with survival expected in only about 20-30% of such patients. Novel targeted therapeutic approaches are necessary to reduce treatment related toxicity in the up-front setting and improve survival in the relapsed/refractory setting. Analyses of genomic abnormalities in BL have identified increased activation of the PI3K/Akt/mTOR pathway in BL, induced by tonic B-cell receptor signaling and increased expression of Myc induced microRNAs (miRs), as having a significant role in Burkitt lymphomagensis. Additionally, recent reports have implicated higher expression of PI3K activating, Myc induced miRs in pediatric patients with a higher risk of relapse. While focused targeting of PI3K with the PI3K-delta isoform specific inhibitor idelalisib has led to significant activity in indolent B-cell lymphomas, limited activity has been noted in the setting of more aggressive forms. A broader inhibition of both upstream and downstream components of the pathway may exhibit more significant anti-lymphoma activity. To this end, we investigated the in vitro effects of PI3K/Akt/mTOR pathway inhibition with the dual pan-PI3K/mTOR inhibitor Omipalisib (GSK458) in chemotherapy-sensitive and -resistant BL cell line models. Methods: The in vitro effect of omipalisib was investigated in the BL cell lines Raji, Raji 4RH (chemotherapy-rituximab resistant), Raji 8RH (rituximab resistant), Ramos, and Daudi. Cell viability following exposure to omipalisib alone and in combination with cytotoxic chemotherapeutic agents was analyzed using Cell-Titer Glo and Alamar Blue assays. Apoptosis was analyzed using western blotting for PARP and by flow cytometry with Annexin V-propidium iodide staining. Downstream targets in the PI3K/Akt/mTOR pathway were analyzed using western blotting. Cell cycle analysis was performed by flow cytometry using propidium iodide staining. Synergistic activity of combination exposures was determined by calculation of a combination index using CalcuSyn software. Results: In vitro exposure of BL cell lines to omipalisib in concentrations ranging from 0.05μM to 50μM for 24, 48 or 72 hours resulted in a dose and time dependent decrease in viable cells with significant activity noted at even low nM concentrations (48 hour IC50 values: Raji=1.2μM, Raji 4RH=0.02μM, Raji 8RH=1.9μM, Ramos=0.01μM, Daudi=0.01μM). Flow cytometry for Annexin V and propidium iodide, after 72 hours of single agent exposure to omipalisib, showed a marked induction of apoptosis in all cell lines. For example, at an omipalisib concentration of 200nM, the percentage of Annexin V positive cells were Raji=40.7%, Raji 4RH=4.4%, Raji 8RH=41.5%, Ramos=59.4% and Daudi=46.9%. Approximately ten-fold higher omipalisib concentrations were required to induce similar degrees of apoptosis in the chemotherapy resistant Raji 4RH cell line compared to chemotherapy sensitive cell lines. Western blotting for downstream targets of the PI3K/Akt/mTOR pathway, including S6 and GSK3Β, showed a reduction in phosphorylation after 30 minutes of exposure to omipalisib in all cell lines. Determination of cell cycle progression following exposure to omipalisib for 72 hours at concentrations ranging from 0.006μM to 25μM showed dose-dependent cell cycle arrest in G1 phase in all cell lines; however the chemotherapy resistant Raji 4RH cells arrested in G2/M at higher concentrations. When BL cells were exposed to omipalisib in combination with either doxorubicin or dexamethasone, synergistic anti-tumor activity was observed in all cell lines tested. Conclusion: Inhibition of PI3K and mTOR by the dual inhibitor omipalisib suppresses activation of the PI3K/Akt/mTOR pathway leading to impaired BL cell proliferation with G1 cell cycle arrest and induction of apoptosis in chemotherapy-sensitive and -resistant cell line models of BL. Inhibition of the PI3K/Akt/mTOR pathway with omipalisib also increases the in vitro response to cytotoxic chemotherapeutic agents. Our findings note the pre-clinical activity of PI3K/Akt/mTOR pathway inhibition in BL and highlight the relevance of pursuing PI3K/Akt/mTOR pathway inhibition as a potential therapeutic option in BL. Disclosures No relevant conflicts of interest to declare.

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Targeting BET Bromodomains in Pre-Clinical Models of Burkitt Lymphoma

Blood ◽

10.1182/blood.v128.22.5381.5381 ◽

2016 ◽

Vol 128 (22) ◽

pp. 5381-5381 ◽

Cited By ~ 1

Author(s):

Thomas Ippolito ◽

Juan J Gu ◽

Gregory Tang ◽

Cory Mavis ◽

Rodney R. Miles ◽

...

Keyword(s):

Western Blot ◽

Cell Viability ◽

Cell Line ◽

Cell Lines ◽

Burkitt Lymphoma ◽

Mtor Pathway ◽

Synergistic Activity ◽

Pi3k Activation ◽

Induction Of Apoptosis

Abstract Background: Burkitt lymphoma (BL) is the most common NHL type in children. Although treatment for pediatric BL has improved significantly, there is an urgent need for novel therapies that reduce the toxicity of modern treatment regimens and improve on the dismal survival observed in the relapsed/refractory setting where only about 20-30% of patients survive their disease. Recent reports have implicated co-activation of c-Myc and PI3K in Burkitt lymphomagenesis. Genomic analysis of recurrent oncogenic mutations in BL have identified tonic B-cell receptor signaling and the over-expression of Myc induced microRNAs from the MIR17-92 family, e.g. mir17 and mir19, as possible mechanisms of PI3K activation in BL. Mir17 and mir19, have been implicated in Burkitt lymphomagenesis and their overexpression may be associated with a higher risk of relapse. The protein phosphatase and tensin homolog (PTEN) is a major regulator of PI3K pathway activation. MIR17-92 cluster members have been shown to target PTEN leading to increased PI3K activation. We have previously identified increased expression of mir17 and mir19 along with increased activation of AKT in cell line models of chemotherapy resistant BL suggesting a potential mechanism for increased resistance. BET bromodomains interact with chromatin and enhance transcriptional activation of numerous genes including c-Myc. Thus, BET bromodomains represent a promising target in BL. To investigate the effects of inhibition of c-Myc driven activation of the PI3K/AKT/mTOR pathway, we characterized the activity of the highly potent small molecule bromodomain inhibitor JQ1 in chemotherapy sensitive and resistant BL cell lines. Additionally, we analyzed the ability to enhance anti-lymphoma activity of PI3K/Akt/mTOR pathway inhibition in BL by the combination of BET bromodomain inhibition and targeted inhibition of the PI3K/AKT/mTOR pathway. Methods: The in vitro activity of JQ1 was investigated in the BL cell lines Raji, Raji 4RH (chemotherapy-rituximab resistant), Raji 8RH (rituximab resistant), Ramos, and Daudi. Cell Viability following exposure to JQ1 alone and in combination with the PI3K/mTOR inhibitor omipalisib (GSK458)) was analyzed using Cell-Titer Glo or Alamar Blue assays following 24, 48, and 72 hour exposure over a range of inhibitor concentrations. Induction of apoptosis was analyzed using western blotting for cleaved PARP. C-Myc expression following JQ1 exposure was determined by western blot following 48 hour JQ1 exposure. The effect of JQ1 exposure on the expression of c-Myc induced microRNA expression was determined by qRT-PCR in cells exposed to JQ1 for 48hours. Synergy of combination exposures was determined using CalcuSyn to generate combination index (CI) values. Results: In vitro exposure of BL cell lines to JQ1 for 24, 48, and 72 hours resulted in a significant dose and time dependent decrease in viable cells (72 hour IC50 values: Raji 0.12µM, Raji 4RH 1.7µM, Raji 8RH 0.7µM, Ramos 0.22µM and Daudi 4µM). There was an increase in cleaved PARP after 72 hour exposure indicating induction of apoptosis. While single agent effect was seen in the resistant Raji 4RH cell line, activity was noted to primarily occur at the higher end of the dosing. Western blot analysis demonstrated a reduction in c-Myc expression following exposure to JQ1 1µM for 24 hours (relative band intensity normalized to control: Raji=0.12, Raji 4RH=0.18, Raji 8RH=0.11). qPCR showed a reduction in Mir17 relative transcription levels after 48 hours of exposure to JQ1 2.5mM (relative expression compared to control: Raji=0.72, Raji 4RH=0.98, Raji 8RH=0.83, Ramos=0.57, Daudi=0.46). When combined with omipalisib, an increased effect on cell viability was noted. The combination effect was noted to be synergistic (CI<0.9) at multiple dose combinations while other combinations exhibited primarily additive effects. Conclusion: In vitro inhibition of BET bromodomains with JQ1 results in a decrease in c-Myc expression and a decrease in c-Myc dependent miR expression with impaired proliferation and induction of apoptosis in chemotherapy-sensitive and -resistant BL cell lines. Augmented, and in some cases synergistic, activity is also noted with dual inhibition of BET bromodomains and the PI3K/Akt/mTOR pathway in BL cell lines. Disclosures No relevant conflicts of interest to declare.

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A Novel Camptothecin Derivative 3j Inhibits Nsclc Proliferation Via Induction of Cell Cycle Arrest By Topo I-Mediated DNA Damage

Anti-Cancer Agents in Medicinal Chemistry ◽

10.2174/1871520619666181207102037 ◽

2019 ◽

Vol 19 (3) ◽

pp. 365-374 ◽

Cited By ~ 1

Author(s):

Yang Liu ◽

Jingyin Zhang ◽

Shuyun Feng ◽

Tingli Zhao ◽

Zhengzheng Li ◽

...

Keyword(s):

Cell Cycle ◽

Flow Cytometry ◽

Dna Damage ◽

Cyclin D ◽

Dna Relaxation ◽

Cycle Arrest ◽

H460 Cell ◽

H1975 Cell

Objective: The aim of this study is to investigate the inhibitory effect of camptothecin derivative 3j on Non-Small Cell Lung Cancer (NSCLCs) cells and the potential anti-tumor mechanisms. Background: Camptothecin compounds are considered as the third largest natural drugs which are widely investigated in the world and they suffered restriction because of serious toxicity, such as hemorrhagic cystitis and bone marrow suppression. Methods: Using cell proliferation assay and S180 tumor mice model, a series of 20(S)-O-substituted benzoyl 7- ethylcamptothecin compounds were screened and evaluated the antitumor activities in vitro and in vivo. Camptothecin derivative 3j was selected for further study using flow cytometry in NSCLCs cells. Cell cycle related protein cyclin A2, CDK2, cyclin D and cyclin E were detected by Western Blot. Then, computer molecular docking was used to confirm the interaction between 3j and Topo I. Also, DNA relaxation assay and alkaline comet assay were used to investigate the mechanism of 3j on DNA damage. Results: Our results demonstrated that camptothecin derivative 3j showed a greater antitumor effect in eleven 20(S)-O-substituted benzoyl 7-ethylcamptothecin compounds in vitro and in vivo. The IC50 of 3j was 1.54± 0.41 µM lower than irinotecan with an IC50 of 13.86±0.80 µM in NCI-H460 cell, which was reduced by 8 fold. In NCI-H1975 cell, the IC50 of 3j was 1.87±0.23 µM lower than irinotecan (IC50±SD, 5.35±0.38 µM), dropped by 1.8 fold. Flow cytometry analysis revealed that 3j induced significant accumulation in a dose-dependent manner. After 24h of 3j (10 µM) treatment, the percentage of NCI-H460 cell in S-phase significantly increased (to 93.54 ± 4.4%) compared with control cells (31.67 ± 3.4%). Similarly, the percentage of NCI-H1975 cell in Sphase significantly increased (to 83.99 ± 2.4%) compared with control cells (34.45 ± 3.9%) after treatment with 10µM of 3j. Moreover, increased levels of cyclin A2, CDK2, and decreased levels of cyclin D, cyclin E further confirmed that cell cycle arrest was induced by 3j. Furthermore, molecular docking studies suggested that 3j interacted with Topo I-DNA and DNA-relaxation assay simultaneously confirmed that 3j suppressed the activity of Topo I. Research on the mechanism showed that 3j exhibited anti-tumour activity via activating the DNA damage response pathway and suppressing the repair pathway in NSCLC cells. Conclusion: Novel camptothecin derivative 3j has been demonstrated as a promising antitumor agent and remains to be assessed in further studies.

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lncRNA CASC19 Contributes to Radioresistance of Nasopharyngeal Carcinoma by Promoting Autophagy via AMPK-mTOR Pathway

International Journal of Molecular Sciences ◽

10.3390/ijms22031407 ◽

2021 ◽

Vol 22 (3) ◽

pp. 1407

Author(s):

Hongxia Liu ◽

Wang Zheng ◽

Qianping Chen ◽

Yuchuan Zhou ◽

Yan Pan ◽

...

Keyword(s):

Nasopharyngeal Carcinoma ◽

Cell Line ◽

Malignant Tumors ◽

Underlying Mechanism ◽

Mtor Pathway ◽

Rna Seq ◽

Cellular Autophagy ◽

First Time

Nasopharyngeal carcinoma (NPC) is one of the most frequent head and neck malignant tumors and is majorly treated by radiotherapy. However, radiation resistance remains a serious obstacle to the successful treatment of NPC. The aim of this study was to discover the underlying mechanism of radioresistance and to elucidate novel genes that may play important roles in the regulation of NPC radiosensitivity. By using RNA-seq analysis of NPC cell line CNE2 and its radioresistant cell line CNE2R, lncRNA CASC19 was screened out as a candidate radioresistance marker. Both in vitro and in vivo data demonstrated that a high expression level of CASC19 was positively correlated with the radioresistance of NPC, and the radiosensitivity of NPC cells was considerably enhanced by knockdown of CASC19. The incidence of autophagy was enhanced in CNE2R in comparison with CNE2 and another NPC cell line HONE1, and silencing autophagy with LC3 siRNA (siLC3) sensitized NPC cells to irradiation. Furthermore, CASC19 siRNA (siCASC19) suppressed cellular autophagy by inhibiting the AMPK/mTOR pathway and promoted apoptosis through the PARP1 pathway. Our results revealed for the first time that lncRNA CASC19 contributed to the radioresistance of NPC by regulating autophagy. In significance, CASC19 might be a potential molecular biomarker and a new therapeutic target in NPC.

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Silencing VEGF enhances the radiosensitivity of the radioresistant human nasopharyngeal carcinoma cell line CNE-2R by inhibiting autophagy through the activation of mTOR pathway

10.21203/rs.3.rs-26678/v1 ◽

2020 ◽

Author(s):

Li Chen ◽

Guoxiang Lin ◽

Kaihua Chen ◽

Fangzhu Wan ◽

Yongchu Sun ◽

...

Keyword(s):

Dna Damage ◽

Nasopharyngeal Carcinoma ◽

Cell Line ◽

Western Blotting ◽

Xenograft Model ◽

Mtor Pathway ◽

Angiogenic Factor ◽

Cell Counting

Abstract Background: Vascular endothelial growth factor (VEGF) is an important pro-angiogenic factor. VEGF was reported to promote the occurrence of autophagy, which enhanced to the radioresistance of tumors. The purpose of our study was to investigate the influence of VEGF silencing on the radiosensitivity of nasopharyngeal carcinoma radioresistant cell line CNE-2R and the underlying mechanisms.Methods: The radiosensitivity of CNE-2R cells after silencing VEGF was detected by cell counting kit 8 (CCK-8) and clonogenic assay, cell cycle and apoptosis was subjected to flow cytometry. DNA damage and autophagy were observed by immunofluorescence and western blotting. The interaction between VEGF and mTOR was confirmed by western blotting and co-immunoprecipitation analysis. In vivo, the effect of VEGF on radiosensitivity of NPC cells was investigated through xenograft model, furthermore, immunohistochemistry and TUNEL assay were used to further verify the relationship between autophagy and radiosensitivity in NPC after VEGF depletion.Results: Downregulation of VEGF significantly inhibited cell proliferation and induced apoptosis of CNE-2R cells after radiotherapy in vitro and in vivo. In addition, VEGF knockdown not only decreased autophagy level, but also delayed the DNA damage repair in CNE-2R cells after irradiation. Mechanistically, silencing VEGF suppressed autophagy through the activation of mTOR pathway.Conclusion: VEGF depletion increased radiosensitivity of NPC radioresistant cell CNE-2R by suppressing autophagy via the activation of mTOR pathway.

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Raddeanin A Induces Apoptosis and Cycle Arrest in Human HCT116 Cells through PI3K/AKT Pathway Regulation In Vitro and In Vivo

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2019/7457105 ◽

2019 ◽

Vol 2019 ◽

pp. 1-11

Author(s):

Chunqin Meng ◽

Yuhao Teng ◽

Xiaodong Jiang

Keyword(s):

Cell Cycle ◽

Cell Line ◽

Akt Signaling ◽

Akt Signaling Pathway ◽

Cycle Arrest ◽

Colorectal Cell ◽

Pathway Regulation ◽

Hct116 Cells

This study aimed to investigate the in vitro and in vivo effects of Raddeanin A on apoptosis and the cell cycle in the human colorectal cell line, HCT116, and to explore the possible underlying mechanisms of action. We found the growth inhibition rate gradually increased as the drug concentration increased via the 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide (MTT) assay, which indicated that Raddeanin A significantly inhibited the growth of HCT116 cells. Flow cytometry (FCM) showed that Raddeanin A concentration-dependently induced apoptosis in HCT116 cells. In addition, the percentage of cells in the G0/G1phase was noticeably increased, which indicated that Raddeanin A blocked cell cycle progression in HCT116 cells and caused arrest in the G0/G1phase. Moreover, the expression of proteins involved in the PI3K/AKT signaling pathway (e.g., p-PI3K and p-AKT) was decreased. The results showed that in vivo revealed that Raddeanin A significantly inhibited tumor growth in an HCT116-xenografted mouse model; apoptotic cells were also detected in the tumor tissue. The expression of the tissue proteins cyclinD1, cyclinE, p-PI3K, and p-AKT was decreased. The above results show that the Raddeanin A exerted a strong antitumor effect in the human colorectal cell line HCT116 both in vitro and in vivo. This effect may be caused by the induction of apoptosis and cycle arrest achieved through PI3K/AKT signaling pathway regulation.

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PI3K/Akt/FOXO3a Pathway Contributes to Thrombopoietin-Induced Proliferation of Primary Megakaryocytes In Vitro and In Vivo Via Modulation of p27Kip1.

Blood ◽

10.1182/blood.v106.11.202.202 ◽

2005 ◽

Vol 106 (11) ◽

pp. 202-202

Author(s):

Takafumi Nakao ◽

Amy E Geddis ◽

Norma E. Fox ◽

Kenneth Kaushansky

Keyword(s):

Cell Cycle ◽

Cell Line ◽

Cell Cycle Progression ◽

Wild Type ◽

Cycle Progression ◽

P27kip1 Expression ◽

Cell Counts ◽

Deficient Mice

Abstract Thrombopoietin (TPO), the primary regulator of megakaryocyte (MK) and platelet formation, modulates the activity of multiple signal transduction molecules, including those in the Jak/STAT, p42/p44 MAPK, and phosphatidylinositol 3-kinase (PI3K)/Akt pathways. In the previous study, we reported that PI3K and Akt are necessary for TPO-induced cell cycle progression of primary MK progenitors. The absence of PI3K activity results in a block of transition from G1 to S phase in these cells (Geddis AE et al. JBC2001276:34473–34479). However, the molecular events secondary to the activation of PI3K/Akt responsible for MK proliferation remain unclear. In this study we show that FOXO3a and its downstream target p27Kip1 play an important role in TPO-induced proliferation of MK progenitors. TPO induces phosphorylation of Akt and FOXO3a in both UT-7/TPO, a megakaryocytic cell line, and primary murine MKs in a PI3K dependent fashion. Cell cycle progression of UT-7/TPO cells is blocked in G1 phase by inhibition of PI3K. We found that TPO down-modulates p27Kip1 expression at both the mRNA and protein levels in UT-7/TPO cells and primary MKs in a PI3K dependent fashion. UT-7/TPO stably expressing constitutively active Akt or a dominant-negative form of FOXO3a failed to induce p27Kip1 expression after TPO withdrawal. Induced expression of an active form of FOXO3a resulted in increased p27Kip1 expression in this cell line. In an attempt to assess whether FOXO3a has an effect of MK proliferation in vivo, we compared the number of MKs in Foxo3a-deficient mice and in wild type controls. Although peripheral blood cell counts of erythrocytes, neutrophils, monocytes and platelets were normal in the Foxo3a-deficient mice, total nucleated marrow cell count of Foxo3a-deficient mice were 60% increased compared with wild type controls. In addition, the increase of MKs was more profound than that of total nucleated marrow cells; CD41+ MKs from Foxo3a-deficient mice increased 2.1-fold, and mature MKs with 8N and greater ploidy increased 2.5-fold, compared with wild type controls. Taken together with the previous observation that p27Kip1-deficient mice also display increased numbers of MK progenitors, our findings strongly suggest that the effect of TPO on MK proliferation is mediated by PI3K/Akt-induced FOXO3a inactivation and subsequent p27Kip1 down-regulation in vitro and in vivo.

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The Novel Kinesin Spindle Protein Inhibitor SB-743921 Exhibits Marked Activity In In Vivo and In Vitro In Models of Aggressive Diffuse Large B-Cell Lymphoma

Blood ◽

10.1182/blood.v116.21.118.118 ◽

2010 ◽

Vol 116 (21) ◽

pp. 118-118

Author(s):

Danielle C Bongero ◽

Luca Paoluzzi ◽

Enrica Marchi ◽

Neisa Roberto ◽

Rafael Escandon ◽

...

Keyword(s):

Cell Cycle ◽

B Cell ◽

Cell Line ◽

Germinal Center ◽

Mitotic Spindle ◽

Tumor Volume ◽

P Value ◽

Kinesin Spindle Protein

Abstract Abstract 118 A mitotic spindle target that has emerged as unique and potentially restricted to the mitotic spindle is Eg5, also known as the kinesin spindle protein (KSP). SB-743921 induces mitotic spindle dysfunction and cell cycle arrest by inhibiting Eg5. Preliminary Phase 1 studies of SB-743921 have demonstrated that this compound is not associated with any neuropathy like other anti-mitotic agents. These studies have also demonstrated a potential signal in patients with relapsed and refractory lymphoma. We investigated the efficacy of SB-743921 in aggressive B-cell lymphomas to evaluate effectiveness and tolerability in germinal center (GCB) and post germinal center (ABC) diffuse large B-cell lymphomas (DLBCL). For cytotoxicity assays, luminescent cell viability was performed using CellTiter-Glo™ followed by acquisition with Biotek Synergy HT. The IC50s were calculated using the Calcusyn software (Biosoft). Cell Cycle was assessed by staining with Vybrant DyeCycle Green (Invitrogen) followed by FACSCalibur acquisition. Whole cell lysate proteins were extracted and quantified according to Bradford assay. After electrophoresis on a gradient 4–20% SDS-PAGE gels the proteins were transferred to nitrocellulose membrane. After blocking and incubation with the primary and the secondary antibodies, the chemiluminescent agent was added and the x-ray films were exposed to the membranes. In vivo experiments were performed with five to 7-week-old severe combined immunodeficiency (SCID) beige mice (Taconic Laboratories, Germantown, NY) injected with 1 × 107 Ly1-DLBCL cells on the flank via a subcutaneous (SQ) route. When tumor volumes approached 80 mm3, mice were separated into cohorts of ten mice each. Tumors were assessed using the two largest perpendicular axes (l, length; w, width) as measured with standard calipers. Tumor volume was calculated using the formula 4/3 r3, where r=(l + w) / 4. Tumor-bearing mice were assessed for weight loss and tumor volume at least twice weekly. The IC50 values for SB-743921 across a panel of different DLBCL lines are listed in table 1. Cell cycle analysis showed that compared to the untreated group, after treatment with 100nM of SB 743921 the percentage of GCB cells in G2/M phase increased from 17.6% to 40.3% (+129%) in Ly7, 23.9% to 40.7 % (+70%) in Sudhl6 and from 17.55% to 32.4% (+85%) in Ly1. In comparison, the percent increase of cells in G2/M for the ABC lines was statistically less (p-value 0.001). For example, Ly10 increased from 15% to 27.6% (+45%), Riva from 29.3% to 36.95% (+26%) and Sudhl2 from 22.6% to 27.6% (+22%). Immunoblot analysis of DLBCL cells treated with SB-743921 probed for Eg5, CyclinB1, and phosphorylated BubR1 revealed that although all cells demonstrated a measurable increase in Eg5, the total Eg5 present varied from cell line to cell line. The In vivo xenograft experiment was conducted with the GCB Ly1 cell line and consisted of 4 cohorts; one control and 3 treatments with doses of 2.5 mg/kg, 5 mg/kg and 10 mg/kg. SB-743921 was administered by the intraperitoneal route on days 1, 5, and 9 on a 23 day cycle for 2 cycles. The graph below displays the inhibition of tumor growth in the cohorts after treatment with SB-74321. All 3 cohorts had a p-value of <0.001 relative to the control. In conclusion, SB-743921 is promising as a single agent for treatment of DLBCL. Future studies exploring the specific cell cycle features of different cell lines with respect to their check-point control will afford new opportunities to better understand the mechanisms of increased resistance in ABC compared to GCB. The data suggests SB 743921 overall is effective in the treatment of DLBCL both in vitro and in vivo. Further studies exploring potential synergistic interactions with conventional chemotherapeutic agents as well as establishing the most effective treatment schedules for the agent may provide a new approach to treating these diseases. Disclosures: Escandon: Cytokinetics: Employment. Wood:Cytokinetics: Employment. O'Connor:Millennium Pharmaceuticals, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding.

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Preclinical Rationale for the Use of the Combined Treatment with the AKT Inhibitor Perifosine and the Multikinase Inhibitor Sorafenib in Hodgkin Lymphoma

Blood ◽

10.1182/blood.v118.21.1653.1653 ◽

2011 ◽

Vol 118 (21) ◽

pp. 1653-1653

Author(s):

Silvia Locatelli ◽

Arianna Giacomini ◽

Anna Guidetti ◽

Loredana Cleris ◽

Michele Magni ◽

...

Keyword(s):

Cell Cycle ◽

Cell Growth ◽

Cell Line ◽

Cell Lines ◽

Drug Combination ◽

Akt Inhibitor ◽

Sorafenib Treatment ◽

Responsive Cell

Abstract Abstract 1653 Introduction: A significant proportion of Hodgkin lymphoma (HL) patients refractory to first-line chemotherapy or relapsing after autologous transplantation are not cured with currently available treatments and require new treatments. The PI3K/AKT and RAF/MEK/ERK pathways are constitutively activated in the majority of HL. These pathways can be targeted using the AKT inhibitor perifosine (Æterna Zentaris GmBH, Germany, EU), and the RAF/MEK/ERK inhibitor sorafenib (Nexavar®, Bayer, Germany, EU). We hypothesized that perifosine in combination with sorafenib might have a therapeutic activity in HL by overcoming the cytoprotective and anti-apoptotic effects of PI3K/Akt and RAF/MEK/ERK pathways. Since preclinical evidence supporting the anti-lymphoma effects of the perifosine/sorafenib combination are still lacking, the present study aimed at investigating in vitro and in vivo the activity and mechanism(s) of action of this two-drug combination. METHODS: Three HL cell lines (HD-MyZ, L-540 and HDLM-2) were used to investigate the effects of perifosine and sorafenib using in vitro assays analyzing cell growth, cell cycle distribution, gene expression profiling (GEP), and apoptosis. Western blotting (WB) experiments were performed to determine whether the two-drug combination affected MAPK and PI3K/AKT pathways as well as apoptosis. Additionally, the antitumor efficacy and mechanism of action of perifosine/sorafenib combination were investigated in vivo in nonobese diabetic/severe combined immune-deficient (NOD/SCID) mice. RESULTS: While perifosine and sorafenib as single agents exerted a limited activity against HL cells, exposure of HD-MyZ and L-540 cell lines, but not HDLM-2 cells, to perifosine/sorafenib combination resulted in synergistic cell growth inhibition (40% to 80%) and cell cycle arrest. Upon perifosine/sorafenib exposure, L-540 cell line showed significant levels of apoptosis (up to 70%, P ≤.0001) associated with severe mitochondrial dysfunction (cytochrome c, apoptosis-inducing factor release and marked conformational change of Bax accompanied by membrane translocation). Apoptosis induced by perifosine/sorafenib combination did not result in processing of caspase-8, -9, -3, or cleavage of PARP, and was not reversed by the pan-caspase inhibitor Z-VADfmk, supporting a caspase-independent mechanism of apoptosis. In responsive cell lines, WB analysis showed that anti-proliferative events were associated with dephosphorylation of MAPK and PI3K/Akt pathways. GEP analysis of HD-MyZ and L-540 cell lines, but not HDLM-2 cells indicated that perifosine/sorafenib treatment induced upregulation of genes involved in amino acid metabolism and downregulation of genes regulating cell cycle, DNA replication and cell death. In addition, in responsive cell lines, perifosine/sorafenib combination strikingly induced the expression of tribbles homologues 3 (TRIB3) both in vitro and in vivo. Silencing of TRIB3 prevented cell growth reduction induced by perifosine/sorafenib treatment. In vivo, the combined perifosine/sorafenib treatment significantly increased the median survival of NOD/SCID mice xenografted with HD-MyZ cell line as compared to controls (81 vs 45 days, P ≤.0001) as well as mice receiving perifosine alone (49 days, P ≤.03) or sorafenib alone (54 days, P ≤.007). In mice bearing subcutaneous nodules generated by HD-MyZ and L-540 cell lines but not HDLM-2 cell line, perifosine/sorafenib treatment induced significantly increased levels of apoptosis (2- to 2.5-fold, P ≤.0001) and necrosis (2- to 8-fold, P ≤.0001), as compared to controls or treatment with single agents. CONCLUSIONS: Perifosine/sorafenib combination resulted in potent anti-HL activity both in vitro and in vivo. These results warrant clinical evaluation in HL patients. Disclosures: No relevant conflicts of interest to declare.

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