scholarly journals Cytoplasmic p21 Mediates 5-Fluorouracil Resistance by Inhibiting Pro-Apoptotic Chk2

Cancers ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 373 ◽  
Author(s):  
Arnatchai Maiuthed ◽  
Chuanpit Ninsontia ◽  
Katharina Erlenbach-Wuensch ◽  
Benardina Ndreshkjana ◽  
Julienne Muenzner ◽  
...  

The oncogenic cytoplasmic p21 contributes to cancer aggressiveness and chemotherapeutic failure. However, the molecular mechanisms remain obscure. Here, we show for the first time that cytoplasmic p21 mediates 5-Fluorouracil (5FU) resistance by shuttling p-Chk2 out of the nucleus to protect the tumor cells from its pro-apoptotic functions. We observed that cytoplasmic p21 levels were up-regulated in 5FU-resistant colorectal cancer cells in vitro and the in vivo Chorioallantoic membrane (CAM) model. Kinase array analysis revealed that p-Chk2 is a key target of cytoplasmic p21. Importantly, cytoplasmic form of p21 mediated by p21T145D transfection diminished p-Chk2-mediated activation of E2F1 and apoptosis induction. Co-immunoprecipitation, immunofluorescence, and proximity ligation assay showed that p21 forms a complex with p-Chk2 under 5FU exposure. Using in silico computer modeling, we suggest that the p21/p-Chk2 interaction hindered the nuclear localization signal of p-Chk2, and therefore, the complex is exported out of the nucleus. These findings unravel a novel mechanism regarding an oncogenic role of p21 in regulation of resistance to 5FU-based chemotherapy. We suggest a possible value of cytoplasmic p21 as a prognosis marker and a therapeutic target in colorectal cancer patients.

Author(s):  
Dan Song ◽  
Ming Guo ◽  
Shuai Xu ◽  
Xiaotian Song ◽  
Bin Bai ◽  
...  

Abstract Background Pseudouridine synthase (PUS) 7 is a member of the PUS family that catalyses pseudouridine formation. It has been shown to be involved in intellectual development and haematological malignancies. Nevertheless, the role and the underlying molecular mechanisms of PUS7 in solid tumours, such as colorectal cancer (CRC), remain unexplored. This study elucidated, for the first time, the role of PUS7 in CRC cell metastasis and the underlying mechanisms. Methods We conducted immunohistochemistry, qPCR, and western blotting to quantify the expression of PUS7 in CRC tissues as well as cell lines. Besides, diverse in vivo and in vitro functional tests were employed to establish the function of PUS7 in CRC. RNA-seq and proteome profiling analysis were also applied to identify the targets of PUS7. PUS7-interacting proteins were further uncovered using immunoprecipitation and mass spectrometry. Results Overexpression of PUS7 was observed in CRC tissues and was linked to advanced clinical stages and shorter overall survival. PUS7 silencing effectively repressed CRC cell metastasis, while its upregulation promoted metastasis, independently of the PUS7 catalytic activity. LASP1 was identified as a downstream effector of PUS7. Forced LASP1 expression abolished the metastasis suppression triggered by PUS7 silencing. Furthermore, HSP90 was identified as a client protein of PUS7, associated with the increased PUS7 abundance in CRC. NMS-E973, a specific HSP90 inhibitor, also showed higher anti-metastatic activity when combined with PUS7 repression. Importantly, in line with these results, in human CRC tissues, the expression of PUS7 was positively linked to the expression of HSP90 and LASP1, and patients co-expressing HSP90/PUS7/LASP1 showed a worse prognosis. Conclusions The HSP90-dependent PUS7 upregulation promotes CRC cell metastasis via the regulation of LASP1. Thus, targeting the HSP90/PUS7/LASP1 axis may be a novel approach for the treatment of CRC.


2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
Gunsmaa Nyamsuren ◽  
Gregor Christof Rapp ◽  
Björn Tampe ◽  
Michael Zeisberg

Abstract Background and Aims Aryl hydrocarbon receptor nuclear translocator (ARNT) mediates anti-fibrotic activity in kidney and liver through induction of ALK3-receptor expression and subsequently increased Smad1/5/8 signaling. While expression of ARNT can be pharmacologically induced by sub-immunosuppressive doses of FK506 or by GPI1046, its anti-fibrotic activity is only realized when ARNT-ARNT homodimers form, as opposed to formation of ARNT-AHR or ARNT-HIF1α heterodimers. Mechanisms underlying ARNTs dimerization decision to specifically form ARNT-ARNT homodimers and possible cues to specifically induce ARNT homodimerization have been previously unknown. We here aimed to elucidate the molecular mechanisms underlying control of ARNT dimerization decision and to explore its therapeutic potential. Method We analyzed dimerization of recombinant and native ARNT by immunoprecipitation, MALDI-TOF mass spectrometry, and LS-MS/MS analysis and proximity ligation assay. Phosphorylation sites were mapped through generation of phosphorylation site mutants and through pharmacological inhibition. For in vivo analysis we challenged mice with model of unilateral ureter obstruction and carbon tetrachloride to induce fibrosis in kidney and liver. Results Here we report that inhibition of PP2A phosphatase activity increases intracellular accumulation of ARNT-ARNT homodimers. This effect is dependent on enhanced ARNT-ARNT homodimerization and decreased ARNT proteolytic degradation, but independent of ARNT transcription (which remains unchanged upon PP2A inhibition). We further identify that Ser77 phosphorylation plays a critical role in ARNT homodimerization, as ARNT-ARNT homodimers do not form with Ser77/Asp-mutant ARNT proteins. In light of previous studies which identified anti-fibrotic activity upon increased ARNT expression, we further demonstrate attenuated fibrosis upon monotherapy with the PP2A inhibitor LB100, and additive anti-fibrotic activities upon combination with pharmacological inducers of ARNT expression FK506 or GPI1046 in murine models of kidney and liver fibrosis. Conclusion Our study provides additional evidence for the anti-fibrotic activity of ARNT and reveals Ser77 phosphorylation as a novel pharmacological target to realize the therapeutic potential of increased ARNT transactivation activity.


Author(s):  
Yiwei Wang ◽  
Minghui Zhao ◽  
Sijia He ◽  
Yuntao Luo ◽  
Yucui Zhao ◽  
...  

Abstract Background Tumor cell repopulation after radiotherapy is a major cause for the tumor radioresistance and recurrence. This study aims to investigate the underlying mechanism of tumor repopulation after radiotherapy, with focus on whether and how necroptosis takes part in this process. Methods Necroptosis after irradiation were examined in vitro and in vivo. And the growth-promoting effect of necroptotic cells was investigated by chemical inhibitors or shRNA against necroptosis associated proteins and genes in in vitro and in vivo tumor repopulation models. Downstream relevance factors of necroptosis were identified by western blot and chemiluminescent immunoassays. Finally, the immunohistochemistry staining of identified necroptosis association growth stimulation factor was conducted in human colorectal tumor specimens to verify the relationship with clinical outcome. Results Radiation-induced necroptosis depended on activation of RIP1/RIP3/MLKL pathway, and the evidence in vitro and in vivo demonstrated that the inhibition of necroptosis attenuated growth-stimulating effects of irradiated tumor cells on living tumor reporter cells. The JNK/IL-8 were identified as downstream molecules of pMLKL during necroptosis, and inhibition of JNK, IL-8 or IL-8 receptor significantly reduced tumor repopulation after radiotherapy. Moreover, the high expression of IL-8 was associated with poor clinical prognosis in colorectal cancer patients. Conclusions Necroptosis associated tumor repopulation after radiotherapy depended on activation of RIP1/RIP3/MLKL/JNK/IL-8 pathway. This novel pathway provided new insight into understanding the mechanism of tumor radioresistance and repopulation, and MLKL/JNK/IL-8 could be developed as promising targets for blocking tumor repopulation to enhance the efficacy of colorectal cancer radiotherapy.


Cancers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 758
Author(s):  
Dan Luo ◽  
Wei Ge

Background: Recurrence and distant organ metastasis is a major cause of death in colorectal cancer (CRC); however, the underlying molecular mechanisms regulating this phenomenon are poorly understood. MeCP2 is a key epigenetic regulator and is amplified in many types of cancer. Its role in CRC and the molecular mechanisms underlying its action remain unknown. Methods: We used western blot and immunohistochemistry to detect MeCP2 expression in CRC tissues, and then investigated its biological functions in vitro and in vivo. Chromatin immunoprecipitation, co-immunoprecipitation, and electrophoretic mobility shift assays were used to detect the associations among MeCP2 (Methyl-CpG binding protein 2), SPI1 (Spi-1 Proto-Oncogene), and ZEB1 (Zinc Finger E-Box Binding Homeobox 1). Results: Using the Cancer Genome Atlas and Oncomine databases, we found MeCP2 expression was upregulated in CRC tissues and this upregulation was related to poor prognosis. Meanwhile, MeCP2 depletion (KO/KD) in CRC cells significantly inhibited stem cell frequency, and invasion and migration ability in vitro, and suppressed CRC metastasis in vivo. Mechanistically, we show MeCP2 binds to the transcription factor SPI1, and aids its recruitment to the ZEB1 promoter. SPI1 then facilitates ZEB1 expression at the transcription level. In turn, ZEB1 induces the expression of MMP14, CD133, and SOX2, thereby maintaining CRC stemness and metastasis. Conclusions: MeCP2 is a novel regulator of CRC metastasis. MeCP2 suppression may be a promising therapeutic strategy in CRC.


Cancers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1878 ◽  
Author(s):  
Robert H. Berndsen ◽  
Nathalie Swier ◽  
Judy R. van Beijnum ◽  
Patrycja Nowak-Sliwinska

Patients with advanced colorectal cancer (CRC) still depend on chemotherapy regimens that are associated with significant limitations, including resistance and toxicity. The contribution of tyrosine kinase inhibitors (TKIs) to the prolongation of survival in these patients is limited, hampering clinical implementation. It is suggested that an optimal combination of appropriate TKIs can outperform treatment strategies that contain chemotherapy. We have previously identified a strongly synergistic drug combination (SDC), consisting of axitinib, erlotinib, and dasatinib that is active in renal cell carcinoma cells. In this study, we investigated the activity of this SDC in different CRC cell lines (SW620, HT29, and DLD-1) in more detail. SDC treatment significantly and synergistically decreased cell metabolic activity and induced apoptosis. The translation of the in-vitro-based results to in vivo conditions revealed significant CRC tumor growth inhibition, as evaluated in the chicken chorioallantoic membrane (CAM) model. Phosphoproteomics analysis of the tested cell lines revealed expression profiles that explained the observed activity. In conclusion, we demonstrate promising activity of an optimized mixture of axitinib, erlotinib, and dasatinib in CRC cells, and suggest further translational development of this drug mixture.


2019 ◽  
Vol 37 (4_suppl) ◽  
pp. 567-567 ◽  
Author(s):  
Lynn Katherine Symonds ◽  
Kelsey K. Baker ◽  
Mary Weber Redman ◽  
Lisa Koch ◽  
Kelly Carter ◽  
...  

567 Background: MACC1, part of the HGF-MET pathway, drives proliferation and regulation of MET expression in vitro. In vivo, MACC1 is associated with tumor progression and studies suggest greater MACC1 expression is associated with resistance to platinum-based chemotherapy. We hypothesized that MACC1 may be a prognostic biomarker in colorectal cancer (CRC). Methods: MACC1 expression was evaluated by immunohistochemistry on tumor microarrays (N = 428). Patients were stage I-III CRC who received an oxaliplatin-based regimen (either with 5-FU (FOLFOX) or capecitabine (XELOX)) within the HeCOG 6C/08 observational study. MACC1 expression was assessed by a blinded GI pathologist using a scale ranging from 0 (no staining) to 3+ (strong expression). Each patient had at least 3 samples and the strongest result was used for the final score. MACC1 positivity was defined as ≥2+ expression and 0-1+ as MACC1-. Cox regression models were used to estimate hazard ratios (HR) for the association of MACC1 expression with patient characteristics, disease-free (DFS), and overall survival (OS). Results: 400/428 CRC tumors were evaluable: 322 (80.5%) were MACC1+ and 78 (19.5%) MACC1-. Mucinous features were less likely in MACC1+ patients (24% vs. 38%, p = 0.02). Other unfavorable features including grade, lymphovascular invasion, perineural invasion, and tumor mutational burden were not significantly different. There was no difference for stage, microsatellite instability, BRAF, KRAS, or NRASstatus between MACC1+/- cancers. There was a trend towards worse survival in MACC1+ patients regardless of treatment (DFS HR 1.55 [95% CI: 0.87, 2.76], OS HR 1.59 [95% CI 0.74, 3.4]). This difference was not statistically significant for OS (p = 0.26) or DFS (p = 0.08) even when stratified by clinicopathologic variables. Conclusions: Patients with MACC1+ CRC tumors who received adjuvant oxaliplatin-based therapy were less likely to have mucinous histology. They had a trend toward independently worse survival that was not significant when accounting for stage and clinicopathologic variables. Studies focused on the predictive role of MACC1 and oxaliplatin in stage III CRC are in progress.


2021 ◽  
Author(s):  
Junshu Li ◽  
Yanhong Ji ◽  
Na Chen ◽  
Huiling Wang ◽  
Chao Fang ◽  
...  

Abstract BackgroundAdenomatous polyposis coli (APC) gene mutations were found in most colorectal cancer patients and functioned as an important inducer of tumorigenesis. Long non-coding RNA (lncRNA) plays a crucial role in the pathogenesis of various diseases, including colorectal cancer (CRC). Here we investigated the role of SURC which is specific upregulated in CRC progression. MethodsBased on the previous microarray results, weighted correlation network analysis (WGCNA) and lncRNA-mRNA co-expression network analysis were used to identify a lncRNA (SURC) and found it was specific up-regulated in CRC patients by qPCR and FISH staining. Chromatin immunoprecipitation (ChIP) assay was used to demonstrate the regulatory effect and mechanism of APC mutation on SURC expression. The effects of SURC on proliferation and cell cycle were determined by in vitro and in vivo experiments. Chromatin Isolation by RNA Purification (CHIRP) and luciferase reporter assay were carried out to illustrate the interaction between SURC, miR-185-5p and CCND2.ResultsWe found that SURC was specific up-regulated in CRC, but not in other solid tumor, when compared with normal adjacent tissues. High expression of SURC correlates with poorer disease-free survival and overall survival of CRC patients. Mutated APC protein resulted in stabilization of β-catenin in CRC, which promotes the transcription of SURC via binding to its promoter. Knockdown of SURC impaired CRC cell proliferation, colony formation and CRC tumor growth. Mechanistically, after transcription, SURC was transferred to cytoplasm and inhibits miR-185-5p expression via binding to miR-185-5p and inhibiting the synthesis of miR-185-5p from pri-miR-185-5p, which results in CCND2 expression.ConclusionCollectively, these results indicated that SURC promoted CRC tumor growth via interacting with miR-185-5p and regulating the activity of miR-185-5p/CCND2 axis which would be a novel diagnosis and prognosis prediction target for CRC.


2019 ◽  
Vol 10 (12) ◽  
Author(s):  
Shutao Pan ◽  
Ming Shen ◽  
Min Zhou ◽  
Xiuhui Shi ◽  
Ruizhi He ◽  
...  

AbstractDysfunction in long noncoding RNAs (lncRNAs) is reported to participate in the initiation and progression of human cancer; however, the biological functions and molecular mechanisms through which lncRNAs affect pancreatic cancer (PC) are largely unknown. Here, we report a novel lncRNA, LINC01111, that is clearly downregulated in PC tissues and plasma of PC patients and acts as a tumor suppressor. We found that the LINC01111 level was negatively correlated with the TNM stage but positively correlated with the survival of PC patients. The overexpression of LINC01111 significantly inhibited cell proliferation, the cell cycle, and cell invasion and migration in vitro, as well as tumorigenesis and metastasis in vivo. Conversely, the knockdown of LINC01111 enhanced cell proliferation, the cell cycle, and cell invasion and migration in vitro, as well as tumorigenesis and metastasis in vivo. Furthermore, we found that high expression levels of LINC01111 upregulated DUSP1 levels by sequestering miR-3924, resulting in the blockage of SAPK phosphorylation and the inactivation of the SAPK/JNK signaling pathway in PC cells and thus inhibiting PC aggressiveness. Overall, these data reveal that LINC01111 is a potential diagnostic biomarker for PC patients, and the newly identified LINC01111/miR-3924/DUSP1 axis can modulate PC initiation and development.


2017 ◽  
Vol 102 (12) ◽  
pp. 4435-4447 ◽  
Author(s):  
Lorna C Gilligan ◽  
Habibur P Rahman ◽  
Anne-Marie Hewitt ◽  
Alice J Sitch ◽  
Ali Gondal ◽  
...  

Abstract Context Estrogens affect the incidence and progression of colorectal cancer (CRC), although the precise molecular mechanisms remain ill-defined. Objective The present study investigated prereceptor estrogen metabolism through steroid sulphatase (STS) and 17β-hydroxysteroid dehydrogenase activity and subsequent nongenomic estrogen signaling in human CRC tissue, in The Cancer Genome Atlas colon adenocarcinoma data set, and in in vitro and in vivo CRC models. We aimed to define and therapeutically target pathways through which estrogens alter CRC proliferation and progression. Design, Setting, Patients, and Interventions Human CRC samples with normal tissue-matched controls were collected from postmenopausal female and age-matched male patients. Estrogen metabolism enzymes and nongenomic downstream signaling pathways were determined. CRC cell lines were transfected with STS and cultured for in vitro and in vivo analysis. Estrogen metabolism was determined using an ultra-performance liquid chromatography–tandem mass spectrometry method. Primary Outcome Measure The proliferative effects of estrogen metabolism were evaluated using 5-bromo-2′-deoxyuridine assays and CRC mouse xenograft studies. Results Human CRC exhibits dysregulated estrogen metabolism, favoring estradiol synthesis. The activity of STS, the fundamental enzyme that activates conjugated estrogens, is significantly (P < 0.001) elevated in human CRC compared with matched controls. STS overexpression accelerates CRC proliferation in in vitro and in vivo models, with STS inhibition an effective treatment. We defined a G-protein–coupled estrogen receptor (GPER) proproliferative pathway potentially through increased expression of connective tissue growth factor in CRC. Conclusion Human CRC favors estradiol synthesis to augment proliferation via GPER stimulation. Further research is required regarding whether estrogen replacement therapy should be used with caution in patients at high risk of developing CRC.


2020 ◽  
Author(s):  
Ying Cui ◽  
Yibing Bai ◽  
Jiani Yang ◽  
Yuanfei Yao ◽  
Chunhui Zhang ◽  
...  

Abstract Mitochondria-localized sirtuin 4 (SIRT4) is associated with malignant phenotypes in colorectal cancer. However, the molecular mechanisms that drive SIRT4-mediated carcinogenesis are unclear. Initially, we confirmed expression of SIRT4 in colorectal cancer through public database and in colorectal cancer patient tissues using quantitative real-time reverse transcription PCR. We established HCT116 colorectal cells that overexpressed SIRT4 and HT29 cells were transfected with plasmids bearing a small interfering RNA siRNA construct to silence SIRT4. Assays to determine the malignant phenotypes (proliferation, invasion and migration) were performed. Xenograft in-vivo models were also constructed. A protein interactome network was built using differentially expressed proteins identified using the liquid chromatography/tandem mass spectrophotometry, the findings of which were confirmed using coimmunoprecipitation, western blotting, and phenotype rescue experiments. Decreased SIRT4 expression was associated with malignant phenotypes in vitro and in vivo. The ribosomal biogenesis pathway was enriched in the interactome network. SIRT4 suppression activated glutaminase, thereby initiating AKT activation. Our research provided novel insights into the molecular mechanisms underlying colorectal cancer, and identified that SIRT4 exerts its antitumor activity in colorectal cancer possibly dependent on glutaminase to inhibit proliferation, migration, and invasion via the AKT/GSK3β/CyclinD1 pathway.


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