scholarly journals MBRS-18. TUMOR SUPPRESSOR p53 DEFINES THE THERAPEUTIC RESPONSES IN TREATMENT OF MEDULLOBLASTOMA

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii401-iii401
Author(s):  
Avinash L Mohan ◽  
Anubhav G Amin ◽  
Michael E Tobias ◽  
Mohan K Das ◽  
Raphael S S de Medeiros ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Drug Resistance ◽  
Disease Progression ◽  
Combined Treatment ◽  
Metastatic Potential ◽  
Mutant P53 ◽  
P53 Expression ◽  
P53 Signaling ◽  
Mutational Status ◽  
Gli 1

Abstract Medulloblastoma (MB) is the most common primary pediatric malignant brain tumor. Current molecular analysis classifies MB into 4 groups, classic (WNT), sonic hedgehog (Shh), group 3, and group 4. Furthermore, atypical p53 signaling is associated with disease progression and confers poor prognosis. This study investigated the correlation of mutational status of p53 and iSO17q with disease progression and metastatic potential. In addition, we used small molecule inhibitors of PI3K (Buparlisib; BKM120) and HDAC (LBH-589) on a p53-mutant MB cell line to find novel therapeutic targets. Efficacy of these drugs were assessed using functional assays (cell proliferation, migration, cell cycle and drug resistance). MB tumors (n=53) were evaluated for GLI-1, GAB-1, NPR, KV1, YAP expression and mutant p53 via immunohistochemistry and correlated to patient outcomes. Results demonstrated that: 1) high expression of GAB-1 and YAP were found in the Shh group, while KV1 expression was present in all subtypes; 2) mutant p53 expression was present in various subsets of MB with no apparent correlation with metastasis or disease progression; 3) patients displaying iSO17q (determined by fluorescence in situ hybridization (FISH) technique) exhibited metastatic disease; 4) LBH-589 and BKM120 caused both time and dose-dependent inhibition of MB cell proliferation and migration; 5) combined treatment of BKM120 and LBH-589 had a synergistic effect; 6) MB cells demonstrated drug-resistance to BKM120. In conclusion, these findings underscore use of Buparlisib and LBH-589 in treatment of MB. Further, the role of mutant p53 in disease progression remains elusive, whereas presence of iSO17q defines metastatic potential.

High p53 Protein Expression LEVEL Independent Of Mutational Status Is An Adverse Prognostic Factor For Survival In ACUTE Myeloid Leukemia

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1330-1330
Author(s):  
Alfonso Quintas-Cardama ◽  
Sean M. Post ◽  
Kensuke Kojima ◽  
Yi Hua Qiu ◽  
Michael Andreeff ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Mutant P53 ◽  
P53 Mutations ◽  
Wild Type ◽  
P53 Pathway ◽  
P53 Expression ◽  
Mutational Status ◽  
Wild Type P53 ◽  
Acute Myeloid

Abstract Background The tumor suppressor p53 is frequently mutated in human cancer, including acute myeloid leukemia (AML), particularly in cases with high-risk cytogenetics. It has been shown that p53 stabilization, which frequently occurs when the protein is mutated, can compromise its function. We have shown that p53 stabilization, regardless of the presence of mutations, suggesting alterations of other components in the p53 pathway. Methodology p53 expression was determined using high-throughput reverse phase protein array (RPPA) technology in 719 samples from 511 pts. Eleven CD34+ bone marrow (BM) and 10 normal peripheral blood (PB) lymphocyte samples were used as controls. Samples were printed as 5 serial 1:2 dilutions in duplicate using an Aushon 2470 Arrayer. Mutational status of p53 alleles was assessed by Sanger sequencing of exons 5 through 9. Expression of components of the p53 pathway was determined using standard immunohistochemical techniques. Nutlin-3a was used in in vitro culture experiments. Results Paired PB- and BM-derived AML samples expressed similar p53 levels (p=0.25). A trend towards higher p53 expression at relapsed was observed among 47 paired diagnosis/relapse samples (p=0.07). p53 expression correlated directly with CD34 (p=0.001) and inversely correlated with WBC (p=0.007), PB and BM blast burden (p=0.0001), and survival (p=0.01). High p53 (p53high) expression was more associated with unfavorable cytogenetics, particularly -5 (p=0.00001). p53high resulted in lower complete remission (CR) rates (51% vs 56%; p=??), higher relapsed rates (82% vs 62%; p=??), and shorter median overall survival (OS; 29.8 vs. 51 wks, p=0.009) compared to p53low pts. Most cases with p53high had unfavorable cytogenetics. We next correlated p53 stabilization with the presence of p53 mutations in 68 pts. p53 mutations were detected in 20/54 (37%) p53high pts and in 0/14 (0%) pts with p53low. p53high, either in the presence (29 wks) or in the absence (24 wks) of p53 mutations (p=1.0), was associated with significantly shorter OS compared with p53low pts (56 wks; p=0.05). Multivariate analysis revealed p53 expression to be an independent risk factor for survival in AML (p=0.02). p53high was positively correlated with p53pSER15 (p=0.00001), Rbp807p811 (p=0.0002), BAD (p=0.0001), cleaved PARP (p=0.002), and cleaved PARP (p=0.01), and negatively with p21 (p=0.01), and MDM2 (p=0.001).Given the similar OS in p53high pts carrying mutant or wild-type p53, we scored the immunohistochemical expression of MDM2, MDM4, and p21 in 30 p53high pts (9 p53 mutated, 21 wild-type p53). Overexpression of MDM2 was observed in 44% vs 48% pts with mutant vs wild-type p53, respectively, whereas rates were 67% vs 62% for MDM4, and 0% vs 19% for p21, for each respective genotype. Overall, of the 21 p53high pts carrying wild-type p53, 15 (71%) had overexpression of MDM2 and/or MDM4, whereas 81% had no p21 expression, indicating deficient activation of the p53 pathway similar to those cases carrying mutant p53. We are currently assessing response to nutlin-3a therapy in 24 primary AML samples (4 mutant p53, 20 wild-type p53). Results showing the impact of p53 mutation and/or stabilization, and expression levels of MDM2, MDM4, and p21 on nutlin-3a therapy will be presented. Conclusions p53 stabilization (p53high) is a powerful predictive and prognostic factor in AML, which is independent of the presence of mutant p53 alleles. Poor outcomes in pts with p53high lacking p53 mutations are very frequently associated with overexpression of negative regulators of p53 such as MDM2 and/or MDM4 and p21 downregulation, indicating a functionally altered p53 pathway. These findings may have implications for therapies targeting the MDM2/p53 axis in AML. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Many Distinct Ways Lead to Drug Resistance in BRAF- and NRAS-Mutated Melanomas

Life ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 424
Author(s):  
Jiri Vachtenheim ◽  
Lubica Ondrušová
Keyword(s):  
Drug Resistance ◽  
Mapk Pathway ◽  
Combined Treatment ◽  
Initial Response ◽  
Metastatic Potential ◽  
Advanced Melanoma ◽  
Driver Mutations ◽  
Erk Pathway ◽  
Development Of Resistance ◽  
Tumor Eradication

Advanced melanoma is a relentless tumor with a high metastatic potential. The combat of melanoma by using the targeted therapy is impeded because several major driver mutations fuel its growth (predominantly BRAF and NRAS). Both these mutated oncogenes strongly activate the MAPK (MEK/ERK) pathway. Therefore, specific inhibitors of these oncoproteins or MAPK pathway components or their combination have been used for tumor eradication. After a good initial response, resistant cells develop almost universally and need the drug for further expansion. Multiple mechanisms, sometimes very distant from the MAPK pathway, are responsible for the development of resistance. Here, we review many of the mechanisms causing resistance and leading to the dismal final outcome of mutated BRAF and NRAS therapy. Very heterogeneous events lead to drug resistance. Due to this, each individual mechanism would be in fact needed to be determined for a personalized therapy to treat patients more efficiently and causally according to molecular findings. This procedure is practically impossible in the clinic. Other approaches are therefore needed, such as combined treatment with more drugs simultaneously from the beginning of the therapy. This could eradicate tumor cells more rapidly and greatly diminish the possibility of emerging mechanisms that allow the evolution of drug resistance.

scholarly journals Inhibition of DNA topoisomerase II alpha gene expression by the p53 tumor suppressor.

1997 ◽  
Vol 17 (1) ◽  
pp. 389-397 ◽  
Author(s):  
Q Wang ◽  
G P Zambetti ◽  
D P Suttle
Keyword(s):  
Gene Expression ◽  
Cell Proliferation ◽  
Topoisomerase Ii ◽  
Luciferase Reporter ◽  
Mutant P53 ◽  
Dna Topoisomerase Ii ◽  
Dna Topoisomerase ◽  
P53 Expression ◽  
Alpha Gene ◽  
Topo Ii

DNA topoisomerase II (topo II) is an essential nuclear enzyme involved in major cellular functions such as DNA replication, transcription, recombination, and mitosis. While an elevated level of topo II alpha is associated with cell proliferation, wild-type (wt) p53 inhibits the expression of various growth-stimulatory genes. To determine if p53 downregulates topo II alpha gene expression, a murine cell line, (10)1val, that expresses a temperature-sensitive p53 was utilized. The (10)1val cells had significantly lower levels of topo II alpha mRNA and protein following incubation for 24 h at 32 degrees C (p53 with wt conformation) than at 39 degrees C (p53 with mutant conformation). The effect of p53 on the human topo II alpha gene promoter was determined by using luciferase reporter plasmids containing varying lengths of the topo II alpha promoter transiently cotransfected into p53-deficient (10)1 cells together with wt or mutant p53 expression plasmids. Transcription from the full-length (bp -557 to +90) topo II alpha promoter was decreased 15-fold by wt p53 in a concentration-dependent manner, whereas mutant p53 exerted much weaker inhibition. Consecutive deletion of the five inverted CCAAT elements (ICEs) from the topo II alpha promoter reduced both the basal promoter activity and wt p53-induced suppression. Transcription of the minimal promoter (-32 to +90), which contains no ICE, was slightly stimulated by wt or mutant p53 expression. When point mutations were introduced into the most proximal ICE (-68), the inhibitory effect of wt p53 was alleviated and stimulation of topo II alpha expression resulted. Our study suggests that wt p53 functions as a transcriptional repressor of topo II alpha gene expression, possibly through a functional interaction with specific ICEs. Inactivation of wt p53 may reduce normal regulatory suppression of topo II alpha and contribute to abortive cell cycle checkpoints, accelerated cell proliferation, and alterations in genomic stability associated with neoplasia.

Developing Therapeutic Strategies for CLL with Mutant p53

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 2476-2476
Author(s):  
Hun Ju Lee ◽  
Miguel Gallardo ◽  
Xiaorui Zhang ◽  
Huaxian Ma ◽  
Alfonso Quintas-Cardama ◽  
...  
Keyword(s):  
Selective Pressure ◽  
Chromosome 17 ◽  
Treatment Modalities ◽  
Mutant P53 ◽  
P53 Mutations ◽  
Wild Type ◽  
P53 Expression ◽  
Mutational Status ◽  
Cytotoxic Treatment ◽  
Therapeutic Responses

Abstract Chronic lymphocytic leukemia (CLL) is a clonal disease marked by genetic heterogeneity, often resulting in varied therapeutic responses. As a consequence of these genetic variations, cytogenetic analyses are routinely employed to select the most efficacious treatment strategies. One of the most critical genetic variants used for CLL risk-stratification is deletion of the short arm of chromosome 17 (17p-). The tumor suppressor TP53 maps to this region, and its loss correlates with dismal outcomes. While FISH analyses for 17p- are routinely performed, the mutational status of TP53 is typically unknown. The importance of p53 mutations in leukemic progression have recently become apparent, as clinical studies have identified subsets of CLL patients that harbor TP53 mutations without an accompanying 17p- (Zenz et. al., JCO 2010); while other studies have suggest that p53 mutations are present in leukemic clones that expand following cytotoxic treatment (Wong et. al., Nature 2015). Thus, it is critical that we identify frontline treatment modalities that do not directly place undo selective pressure on the p53 pathway in CLL patients harboring a single TP53 mutation. In recent clinical trials, the Bruton's tyrosine kinase (BTK) inhibitor, Ibrutinib, has been shown effective in improving progression free survival in patients with CLL regardless of 17p- status (O'Brien et. al., Lancet Oncology 2014). However, little is known regarding how p53 mutations impact therapeutic responses given their known dominant-negative and gain-of-function effects. To this end, we have utilized a preclinical in vivo mouse model of B-CLL (Eµ-TCL1) in the presence or absence of a TP53 hot-spot mutation (p53R172H, corresponding to p53R175H in humans) to study its impact on therapeutic response, survival, and dynamic loss of the remaining wild-type Trp53 allele during the natural course of B-CLL following ibrutinib-based therapy. Cohorts of Eµ-TCL1; p53R172H/+ and Eµ-TCL1; p53WT mice were treated with ibrutinib 25mg/kg/day by oral gavage starting at 8 months of age. Ibrutinib significantly extended survival in both the Eµ-TCL1; p53R172H/+ and Eµ-TCL1; p53WT cohorts (Fig. 1A) and resulted in a reduction in CD5+CD19+ cells (Fig. 1B). Together, these data indicate ibrutinib's therapeutic efficacy even in the presence of mutated p53. To investigate the molecular pathways altered by ibrutinib in both the wild type and p53 mutant setting, we performed RNA-Seq analyses using malignant B-cells from treated and untreated Eµ-TCL1; p53R172H and Eµ-TCL1; p53WT mice. Critically, these analyses revealed that ibrutinib did not impact genes or cellular programs governed by p53 (Fig. 1C). Furthermore, RNA and protein analyses of tumor samples revealed that ibrutinib was directly impacted the BTK-, PLC-, MAPK-, and ERK- pathways regardless of p53 mutational status. Perhaps most important, we did not observe a significant loss of heterozygosity of the remaining wild type Trp53 allele in the ibrutinib treated Eµ-TCL1; p53R172H/+ lymphomas compared to untreated Eµ-TCL1; p53R172H/+. Together, these results directly indicate that ibrutinib does not place undo selective pressure on the remaining wild type Trp53 allele (Fig. 1D) and demonstrates that ibrutinib based treatment modalities may be effective treatment regimens in CLL patients harboring mutant p53. Even though ibrutinib effectively improved overall survival compared to vehicle treated animals, these mice eventually succumbed to the disease. Thus, it will be critical to examine mechanisms of ibrutinib-resistance in the setting of Trp53 mutations. To this end, expression analysis of ibrutinib treated Eµ-TCL1; p53R172H/+ mice revealed an interesting increase in T-cell immune regulatory pathways compared to Eµ-TCL1; p53WT treated cohorts. Currently, we are exploring the mechanism by which mutant p53 expression, exposure to ibrutinib, and regulations of immune-checkpoint genes. Disclosures No relevant conflicts of interest to declare.

Effects of Papaya Leaf Extract (Carica papaya L.) on Cellular Proliferation and Apoptosis in Cervical Cancer Mice Model

2019 ◽  
Vol 17 (5) ◽  
pp. 265-275
Author(s):  
Y. Peristiowati ◽  
Y. Puspitasari ◽  
Indasah
Keyword(s):  
Cervical Cancer ◽  
Cell Proliferation ◽  
Hela Cells ◽  
Leaf Extract ◽  
Caspase 3 ◽  
Methanol Extract ◽  
Negative Control ◽  
Proliferation Index ◽  
Control Group ◽  
P53 Expression

This study is aimed at analyzing the anticancer properties of papaya leaf extract, specifically the inhibition of cell proliferation and apoptotic induction through nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and p53 pathways. Twenty-five mice (Mus musculus), aged 2 months and weighing 20–30 g, was injected with 0.5 mg dexamethasone for 7 days. The mice were then injected intracutaneously with 1 ml of HeLa cells (8 × 106 HeLa cells/microliter). The mice were divided into five groups (5 each): negative control (P1) (5% CMC-Na, sodium carboxymethyl cellulose), treatment II (225 mg/kg BW (body weight) papaya leaves methanol extract), treatment III (450 mg/kg BW), treatment IV (750 mg/kg BW), and treatment PV (2 mg alcohol anticancer drug). Papaya leaf extract treatments were applied for 2 weeks. Then, the tumor tissue was isolated for hematoxylin and eosin staining. Immunohistochemical imaging was used to detect Ki-67, caspase-3, NF-κB, and p53 expression. Further analysis was undertaken using the ImmunoRatio software program. The results indicated that administration of papaya leaf methanol extract significantly increased the expression of NF-κB and p53 at a dose of 450 mg/kg BW. Our results also showed that the mice treated with 450 mg of papaya leaf extract per kg of BW (P3) had the largest increase of caspase-3 expression compared to the negative control group. Papaya leaf ethanol extract decreased the cancer cell proliferation index and increased apoptosis of cancer cells in animal models of cervical cancer; it may also work to increase NF-kB expression and expression of the p53 gene.

Oncogenic LncRNA CASC9 in Cancer Progression

2020 ◽  
Vol 26 ◽  
Author(s):  
Yuying Qi ◽  
Chaoying Song ◽  
Jiali Zhang ◽  
Chong Guo ◽  
Chengfu Yuan
Keyword(s):  
Cell Proliferation ◽  
Drug Resistance ◽  
Cell Growth ◽  
Cancer Cells ◽  
Therapeutic Potential ◽  
Squamous Metaplasia ◽  
Neoplastic Transformation ◽  
Over Expression ◽  
Human Cancers ◽  
Current Review

Background: Long non-coding RNA (LncRNAs), with the length over 200 nucleotides, originate from intergenic, antisense, or promoter-proximal regions, is a large family of RNAs that lack coding capacity. Emerging evidences illustrated that LncRNAs played significant roles in a variety of cellular functions and biological processes in profuse human diseases, especially in cancers. Cancer susceptibility candidate 9 (CASC9), as a member of the LncRNAs group, was firstly found its oncogenic function in esophageal cancer. In following recent studies, a growing amount of human malignancies are verified to be correlated with CASC9, most of which are derived from the squamous epithelium tissue. This present review attempts to highlight the latest insights into the expression, functional roles, and molecular mechanisms of CASC9 in different human malignancies. Methods: In this review, the latest findings related to the pathophysiological processes of CASC9 in human cancers were summarized and analyzed, the associated studies were collected in systematically retrieval of PubMed used lncRNA and CASA9 as keywords. Results: CASC9 expression is identified to be aberrantly elevated in a variety of malignancies. The over-expression of CASC9 has been suggested to accelerate cell proliferation, migration, cell growth and drug resistance of cancer cells, while depress cell apoptosis, revealing its role as an oncogene. Moreover, the current review demonstrated CASC9 closely relates to neoplastic transformation of squamous epithelial cells and squamous metaplasia in non-squamous epithelial tissues. Finally, we discuss the limitations and tremendous diagnostic/therapeutic potential of CASC9 in various human cancers. Results: CASC9 expression is identified to be aberrantly elevated in a variety of malignancies. The over-expression of CASC9 has been suggested to accelerate cell proliferation, migration, cell growth and drug resistance of cancer cells, while depress cell apoptosis, revealing its role as an oncogene. Moreover, the current review demonstrated CASC9 closely relates to neoplastic transformation of squamous epithelial cells and squamous metaplasia in non-squamous epithelial tissues. Finally, we discuss the limitations and tremendous diagnostic/therapeutic potential of CASC9 in various human cancers. Conclusion: Long non-coding RNACASC9 likely served as useful disease biomarkers or therapy targets that could effectively apply in treatment of different kinds of cancers.

scholarly journals Octreotide and Pasireotide Combination Treatment in Somatotroph Tumor Cells: Predominant Role of SST2 in Mediating Ligand Effects

Cancers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1816
Author(s):  
Jessica Amarù ◽  
Federica Barbieri ◽  
Marica Arvigo ◽  
Agnese Solari ◽  
Adriana Bajetto ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Tumor Cells ◽  
Intracellular Signaling ◽  
Somatostatin Receptor ◽  
Combined Treatment ◽  
Primary Cultures ◽  
Receptor Subtype ◽  
Camp Accumulation ◽  
Gh Secretion ◽  
Somatostatin Receptor Ligands

First-generation somatostatin receptor ligands (fg-SRLs), such as octreotide (OCT), represent the first-line medical therapy in acromegaly. Fg-SRLs show a preferential binding affinity for somatostatin receptor subtype-2 (SST2), while the second-generation ligand, pasireotide (PAS), has high affinity for multiple SSTs (SST5 > SST2 > SST3 > SST1). Whether PAS acts via SST2 in somatotroph tumors, or through other SSTs (e.g., SST5), is a matter of debate. In this light, the combined treatment OCT+PAS could result in additive/synergistic effects. We evaluated the efficacy of OCT and PAS (alone and in combination) on growth hormone (GH) secretion in primary cultures from human somatotroph tumors, as well as on cell proliferation, intracellular signaling and receptor trafficking in the rat GH4C1 cell line. The results confirmed the superimposable efficacy of OCT and PAS in reducing GH secretion (primary cultures), cell proliferation, cAMP accumulation and intracellular [Ca2+] increase (GH4C1 cells), without any additive effect observed for OCT+PAS. In GH4C1 cells, co-incubation with a SST2-selective antagonist reversed the inhibitory effect of OCT and PAS on cell proliferation and cAMP accumulation, while both compounds resulted in a robust internalization of SST2 (but not SST5). In conclusion, OCT and PAS seem to act mainly through SST2 in somatotroph tumor cells in vitro, without inducing any additive/synergistic effect when tested in combination.

scholarly journals TP53 Abnormalities and MMR Preservation in 5 Cases of Proliferating Trichilemmal Tumours

2021 ◽  
Vol 8 (2) ◽  
pp. 147-158
Author(s):  
Raquel Martín-Sanz ◽  
José María Sayagués ◽  
Pilar García-Cano ◽  
Mikel Azcue-Mayorga ◽  
María del Carmen Parra-Pérez ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Ultraviolet Radiation ◽  
Mismatch Repair ◽  
Squamous Cell ◽  
Cellular Proliferation ◽  
P53 Expression ◽  
Dna Mismatch ◽  
Molecular Alterations ◽  
Root Sheath ◽  
Close Relationship

Proliferating trichilemmal tumours (PTT) are defined by a benign squamous cell proliferation inside a trichilemmal cystic (TC) cavity. A possible explanation of this proliferative phenomenon within the cyst may be molecular alterations in genes associated to cell proliferation, which can be induced by ultraviolet radiation. Among other genes, alterations on TP53 and DNA mismatch repair proteins (MMR) may be involved in the cellular proliferation observed in PTT. Based on this assumption, but also taking into account the close relationship between the sebaceous ducts and the external root sheath where TC develop, a MMR, a p53 expression assessment and a TP53 study were performed in a series of 5 PTT cases, including a giant one. We failed to demonstrate a MMR disorder on studied PTT, but we agree with previous results suggesting increased p53 expression in these tumours, particularly in proliferative areas. TP53 alteration was confirmed with FISH technique, demonstrating TP53 deletion in most cells.

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