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Platinum-sensitive HGOC residual tumors share joint expression of CRYAB, CEACAM6, SOX2 genes with tumors that acquired resistance

ABSTRACT: Purpose: Most High-Grade Ovarian Carcinomas (HGOCs) are sensitive to carboplatin (CBP)-based chemotherapy but frequently recur within 24 months. Recurrent tumors remain frequently CBP-sensitive and acquire resistance after several CBP cycles. We developed Patient-Derived Xenografts (PDXs) that allow the study of these different stages of CBP-sensitive recurrence and acquisition of resistance. Experimental Design: We generated PDX models from CBP-sensitive HGOC. PDXs were CBP- or mock-treated and tumors were sampled, after treatment and at recurrence. We also isolated models with acquired-resistance from CBP-sensitive PDXs upon repeated CBP treatment. Tumors were characterized transcriptome levels by Affymetrix microarrays. Results: All PDX models reproduced treatment response seen in the patients. CBP-sensitive residual tumors contained non-proliferating tumor cells clusters embedded in a fibrotic mesh. This was absent in CBP-resistant tumors. Residual tumors had marked differences in gene expression when compared to naïve and recurrent tumors, indicating downregulation of cell cycle and proliferation and upregulation of interferon response and epithelial–mesenchymal transition. This gene expression pattern resembled that seen in embryonal diapause and ‘drug-tolerant persister’ states. Residual and acquired-resistance tumors share the overexpression of three genes – CEACAM6, CRYAB, and SOX2. Conclusions: In HGOC PDX, CBP-sensitive recurrences arise from a small population of quiescent, drug-tolerant, residual cells embedded in a fibrotic mesh. These cells overexpress CEACAM6, CRYAB and SOX2, a signature also associated with acquired resistance and poor patient prognosis

ORGANISM(S): Homo sapiens

PROVIDER: GSE198701 | GEO | 2022/03/16

REPOSITORIES: GEO

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Project description:Osteosarcoma (OS) and Ewing’s sarcoma (EW) are the two most common pediatric solid tumors, after brain tumors. Multimodal treatments have significantly improved prognosis in localized disease but outcome is still poor in metastatic patients, for whom therapeutic options are often inadequate. Preclinical drug testing to identify promising treatment options that match the molecular make-up of these tumors is hampered by the lack of appropriate and molecularly well-characterized patient-derived models. To address this need, a panel of patient-derived xenografts (PDX) was established by subcutaneous implantation of fresh, surgically resected OS and EW tumors in NSG mice. Tumors were re-transplanted to next mice generations and fragments were collected for histopathological and molecular characterization. A model was considered established after observing stable histological and molecular features for at least three passages. To evaluate the similarity of the model with primary tumor, we performed a global gene expression profiling and tissue microarrays (TMA), to assess tumor specific biomarkers on tissues from OS/EW tumors and their PDXs (1st and 3rd passage). Moreover, we verified the feasibility of these models for preclinical drug testing. We implanted 61 OS and 29 EW samples: 14/38 (37%) primary OS and 9/23 (39%) OS lung metastases successfully engrafted; while among EW, 5/26 (19%) primary samples and 1/3 (33%) metastases were established. Comparison between patient samples and PDXs, highlighted that histology and genetic characteristics of PDXs were stable and maintained over passages. In particular, correlative analysis between OS and EW samples and their PDXs was extremely high (Pearson’s r range r=0.94-0.96), while patient-derived primary cultures displayed reduced correlation with human samples (r=0.90-0.93), indicating that in vitro adaptation superimpose molecular alterations that create genetic diversion from original tumors. No significant differentially expressed gene profile was observed from the comparison between EW samples and PDXs (fold change > 2, adjusted p <0.05 at paired t-test). In OS, the comparison between OS patient-derived tumors and PDX indicated differences in 397 genes, mostly belonging to immune system functional category. This is in line with the idea that human immune cells are gradually replaced by murine counterparts upon engraftment in the mouse. As proof-of concept, two EW PDX and one OS PDX have been treated with conventional and innovated drugs to test their value in terms of drug-sensitivity prediction. Overall, our study indicated that PDX models maintained the histological and genetic markers of the tumor samples and represent reliable models to test sensitivity to novel drug associations.

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Platinum-sensitive HGOC residual tumors share joint expression of CRYAB, CEACAM6, SOX2 genes with tumors that acquired resistance

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