Nutlin-3a: A Potential Therapeutic Opportunity for TP53 Wild-Type Ovarian Carcinomas

Abstract

Epithelial ovarian cancer is a diverse molecular and clinical disease, yet standard treatment is the same for all subtypes. TP53 mutations represent a node of divergence in epithelial ovarian cancer histologic subtypes and may represent a therapeutic opportunity in subtypes expressing wild type, including most low-grade ovarian serous carcinomas, ovarian clear cell carcinomas and ovarian endometrioid carcinomas, which represent approximately 25% of all epithelial ovarian cancer. We therefore sought to investigate Nutlin-3a—a therapeutic which inhibits MDM2, activates wild-type p53, and induces apoptosis—as a therapeutic compound for TP53 wild-type ovarian carcinomas. Fifteen epithelial ovarian cancer cell lines of varying histologic subtypes were treated with Nutlin-3a with determination of IC50 values. Western Blot (WB) and quantitative real-time polymerase chain reaction (qRT-PCR) analyses quantified MDM2, p53, and p21 expression after Nutlin-3a treatment. DNA from 15 cell lines was then sequenced for TP53 mutations in exons 2-11 including intron-exon boundaries. Responses to Nutlin-3a were dependent upon TP53 mutation status. By qRT-PCR and WB, levels of MDM2 and p21 were upregulated in wild-type TP53 sensitive cell lines, and p21 induction was reduced or absent in mutant cell lines. Annexin V assays demonstrated apoptosis in sensitive cell lines treated with Nutlin-3a. Thus, Nutlin-3a could be a potential therapeutic agent for ovarian carcinomas expressing wild-type TP53 and warrants further investigation.

Mutant p53 Promotes Epithelial Ovarian Cancer by Regulating Tumor Differentiation, Metastasis, and Responsiveness to Steroid Hormones

“…3A, lower panels, black arrows). A previously characterized human ovarian cancer cell line (RMUG-L) that was obtained from a human mucinous ovarian carcinoma, carries heterozygous WT and mutant TP53 (c.614A>G) alleles as confirmed by us recently (23), exhibited a similar morphological and secretory phenotype when innoculated into the intraperitoneal cavity of the severely compromised immunodeficient (SCID) mice (Fig. 3C) (25,26).…”

“…DNA was extracted from microdissected tumor cells using a QIAamp DNA Micro Kit (Qiagen, Valencia, CA) and quantified using a NanoDrop spectrometer (NanoDrop, Rockland, DE). Mutation analysis of TP53 (Exons 5–8) was performed by Sanger Sequencing using PCR primers as described previously (23). …”

Targeting RNA-Polymerase I in Both Chemosensitive and Chemoresistant Populations in Epithelial Ovarian Cancer

“…Interestingly, in the matched chemosensitive/chemoresistant pairs, the two taxane-resistant lines SKOV3TRip2 and HeyA8MDR were more sensitive to CX-5461 than their matched chemosensitive SKOV3ip1 and HeyA8 lines, by 5.5 and 10.5-fold, respectively (Figure 2A, 2B). This difference was independent of TP53 status, as both SKOV3 lines have a missense mutation with no detectable expression at the protein level; and both HeyA8 lines are TP53 wildtype 28 and 33 . These genotypes were confirmed in our cell lines (data not shown).…”

Acetalated Dextran Nanoparticles Loaded into an Injectable Alginate Cryogel for Combined Chemotherapy and Cancer Vaccination

“…Nut‐3a, due to its mechanism of action, can inhibit the proliferation of wt p53 cells 5d,12,20. To assess the antiproliferative effect of free Nut‐3a and Nut‐3a loaded NPs (Nut‐3a‐NPs), we have chosen EL4 cancer cells as a model cell line, since these cells are capable to maintain wt p53 activity and also to be sensitive, both in vitro and in vivo, to Nut‐3a .…”