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High-grade serous ovarian carcinoma (HGSOC) remains the most common and deadly form of ovarian cancer. However, available cell lines usually fail to appropriately represent its complex molecular and histological features. To overcome this drawback, we established OVAR79, a new cell line derived from the ascitic fluid of a patient with a diagnosis of HGSOC, which adds a unique set of properties to the study of ovarian cancer. In contrast to the common models, OVAR79 expresses TP53 without the common hotspot mutations and harbors the rare combination of mutations in both PIK3CA and PTEN genes, together with high-grade chromosomal instability with multiple gains and losses. These features, together with the high proliferation rate, ease of cultivation, and exceptional transfection efficiency of OVAR79, make it a readily available and versatile tool for various studies in the laboratory. We extensively characterized its growth, migration, and sensitivity to platinum- and taxane-based treatments in comparison with the commonly used SKOV3 and OVCAR3 ovarian cell lines. In summary, OVAR79 is an excellent addition for basic and translational ovarian cancer research and offers new insights into the biology of HGSOC.

Ovarian cancer often develops resistance to conventional therapies, hampering their effectiveness. Here, using ex vivo paired ovarian cancer ascites obtained before and after chemotherapy and in vitro therapy-induced secretomes, we show that molecules secreted by ovarian cancer cells upon therapy promote cisplatin resistance and enhance DNA damage repair in recipient cancer cells. Even a short-term incubation of chemonaive ovarian cancer cells with therapy-induced secretomes induces changes resembling those that are observed in chemoresistant patient-derived tumor cells after long-term therapy. Using integrative omics techniques, we find that both ex vivo and in vitro therapy-induced secretomes are enriched with spliceosomal components, which relocalize from the nucleus to the cytoplasm and subsequently into the extracellular vesicles upon treatment. We demonstrate that these molecules substantially contribute to the phenotypic effects of therapy-induced secretomes. Thus, SNU13 and SYNCRIP spliceosomal proteins promote therapy resistance, while the exogenous U12 and U6atac snRNAs stimulate tumor growth. These findings demonstrate the significance of spliceosomal network perturbation during therapy and further highlight that extracellular signaling might be a key factor contributing to the emergence of ovarian cancer therapy resistance., (© 2024. The Author(s).)

Cancer-associated fibroblasts (CAFs) have long been known as one of the most important players in tumor initiation and progression. Even so, there is an incomplete understanding of the identification of CAFs among tumor microenvironment cells as the list of CAF marker genes varies greatly in the literature, therefore it is imperative to find a better way to identify reliable markers of CAFs. To this end, we summarized a large number of single-cell RNA-sequencing data of multiple tumor types and corresponding normal tissues. As a result, for 9 different types of cancer, we identified CAF-specific gene expression signatures and found 10 protein markers that showed strongly positive staining of tumor stroma according to the analysis of IHC images from the Human Protein Atlas database. Our results give an insight into selecting the most appropriate combination of cancer-associated fibroblast markers. Furthermore, comparison of different approaches for studying differences between cancer-associated and normal fibroblasts (NFs) illustrates the superiority of transcriptome analysis of fibroblasts obtained from fresh tissue samples. Using single-cell RNA sequencing data, we identified common differences in gene expression patterns between normal and cancer-associated fibroblasts, which do not depend on the type of tumor., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Kazakova, Anufrieva, Ivanova, Shnaider, Malyants, Aleshikova, Slonov, Ashrafyan, Babaeva, Eremeev, Boichenko, Lukina, Lagarkova, Govorun, Shender and Arapidi.)