Petr Holy

Inhibition of homologous recombination repair by Mirin in ovarian cancer ameliorates carboplatin therapy response in vitro

Abstract Chemoresistance poses one of the most significant challenges of cancer therapy. Carboplatin (CbPt) is one of the most used chemotherapeutics in ovarian cancer (OVC) treatment. MRE11 constitutes a part of homologous recombination (HR), which is responsible for the repair of CbPt-induced DNA damage, particularly DNA crosslinks. The study’s main aim was to address the role of HR in CbPt chemoresistance in OVC and to evaluate the possibility of overcoming CbPt chemoresistance by Mirin-mediated MRE11 inhibition in an OVC cell line. Lower expression of MRE11 was associated with better overall survival in a cohort of OVC patients treated with platinum drugs (TCGA dataset, P < 0.05). Using in vitro analyses, we showed that the high expression of HR genes drives the CbPt chemoresistance in our CbPt-resistant cell line model. Moreover, the HR inhibition by Mirin not only increased sensitivity to carboplatin (P < 0.05) but also rescued the sensitivity in the CbPt-resistant model (P < 0.05). Our results suggest that MRE11 inhibition with Mirin may represent a promising way to overcome OVC resistance. More therapy options will ultimately lead to better personalized cancer therapy and improvement of patients’ survival.

Targeted DNA sequencing of high‐grade serous ovarian carcinoma reveals association of TP53 mutations with platinum resistance when combined with gene expression

AbstractHigh‐grade serous ovarian carcinoma (HGSC) is the most common subtype of ovarian cancer and is among the most fatal gynecological malignancies worldwide, due to late diagnosis at advanced stages and frequent therapy resistance. In 47 HGSC patients, we assessed somatic and germline genetic variability of a custom panel of 144 known or suspected HGSC‐related genes by high‐coverage targeted DNA sequencing to identify the genetic determinants associated with resistance to platinum‐based therapy. In the germline, the most mutated genes were DNAH14 (17%), RAD51B (17%), CFTR (13%), BRCA1 (11%), and RAD51 (11%). Somatically, the most mutated gene was TP53 (98%), followed by CSMD1/2/3 (19/19/36%), and CFTR (23%). Results were compared with those from whole exome sequencing of a similar set of 35 HGSC patients. Somatic variants in TP53 were also validated using GENIE data of 1287 HGSC samples. Our approach showed increased prevalence of high impact somatic and germline mutations, especially those affecting splice sites of TP53, compared to validation datasets. Furthermore, nonsense TP53 somatic mutations were negatively associated with patient survival. Elevated TP53 transcript levels were associated with platinum resistance and presence of TP53 missense mutations, while decreased TP53 levels were found in tumors carrying mutations with predicted high impact, which was confirmed in The Cancer Genome Atlas data (n = 260). Targeted DNA sequencing of TP53 combined with transcript quantification may contribute to the concept of precision oncology of HGSC. Future studies should explore targeting the p53 pathway based on specific mutation types and co‐analyze the expression and mutational profiles of other key cancer genes.

The Role of TRIP6, ABCC3 and CPS1 Expression in Resistance of Ovarian Cancer to Taxanes

The main problem precluding successful therapy with conventional taxanes is de novo or acquired resistance to taxanes. Therefore, novel experimental taxane derivatives (Stony Brook taxanes; SB-Ts) are synthesized and tested as potential drugs against resistant solid tumors. Recently, we reported alterations in ABCC3, CPS1, and TRIP6 gene expression in a breast cancer cell line resistant to paclitaxel. The present study aimed to investigate gene expression changes of these three candidate molecules in the highly resistant ovarian carcinoma cells in vitro and corresponding in vivo models treated with paclitaxel and new experimental Stony Brook taxanes of the third generation (SB-T-121605 and SB-T-121606). We also addressed their prognostic meaning in ovarian carcinoma patients treated with taxanes. We estimated and observed changes in mRNA and protein profiles of ABCC3, CPS1, and TRIP6 in resistant and sensitive ovarian cancer cells and after the treatment of resistant ovarian cancer models with paclitaxel and Stony Brook taxanes in vitro and in vivo. Combining Stony Brook taxanes with paclitaxel caused downregulation of CPS1 in the paclitaxel-resistant mouse xenograft tumor model in vivo. Moreover, CPS1 overexpression seems to play a role of a prognostic biomarker of epithelial ovarian carcinoma patients’ poor survival. ABCC3 was overexpressed in EOC tumors, but after the treatment with taxanes, its up-regulation disappeared. Based on our results, we can suggest ABCC3 and CPS1 for further investigations as potential therapeutic targets in human cancers.

Whole-exome sequencing of epithelial ovarian carcinomas differing in resistance to platinum therapy

Epithelial ovarian carcinoma (EOC) is highly fatal because of the risk of resistance to therapy and recurrence. We performed whole-exome sequencing of blood and tumor tissue pairs of 50 patients with surgically resected EOC. Compared with sensitive patients, platinum-resistant patients had a significantly higher somatic mutational rate inTP53and lower in several genes from the Hippo pathway. We confirmed the pivotal role of somatic mutations in homologous recombination repair genes in platinum sensitivity and favorable prognosis of EOC patients. Implementing the germline homologous recombination repair profile significantly improved the prediction. In addition, distinct mutational signatures, for example, SBS6, and overall mutational load, somatic mutations inPABPC1,PABPC3, andTFAMco-segregated with the resistance status, high-grade serous carcinoma subtype, or overall survival of patients. We generated germline and somatic genetic landscapes of prognostically different subgroups of EOC patients for further follow-up studies focused on utilizing the observed associations in precision oncology.

Molecular Classification in Relation to Prevention of Endometrial Cancer Recurrence and Lifestyle Factors

Endometrial cancer (EC) is one of the most prevalent cancers in women worldwide with a significantly increasing incidence, especially in developed countries. One of the reasons for the increase in the incidence of this disease is the rising incidence of obesity as the biggest risk factor for the development of this disease. Other important risk factors are hypertension, diabetes mellitus and the general ageing of the population. These risk factors are not only associated with a higher risk of developing the disease, but also, for example, with post-operative complications affecting the quality of life of patients after surgery. The molecular classification of endometrial cancer, which has been introduced into clinical practice in recent years, is currently helping physicians to make treatment decisions for individual patients and predict prognosis. In this project, we would like to focus on the relationship of this molecular classification with genomic mutational signatures detected by whole-exome sequencing and their association with lifestyle risk factors for endometrial cancer (obesity - BMI, hypertension, diabetes mellitus), including the extent of staging lymphadenectomy. Identification and detailed analysis of dominant mutational profiles associated with a specific molecular subtype of EC and their influence on the presence of lifestyle risk factors may have a major impact on both disease development and prevention of disease recurrence. The possible relationship of the mutational profile with the extent of staging lymphadenectomy may help in deciding the extent of this surgical procedure, which subsequently affects the quality of life of patients, especially in patients with high BMI. Given the widespread prevalence of lifestyle risk factors in the developed world, a detailed understanding of the relationship between the genetic profile, its alterations and the prevalence of these risk factors, with potentially major implications for treatment success, is crutial.