Abstract 327: Knockdown of VRK1 inhibits the proliferation of small cell neuroendocrine carcinoma of the uterine cervix

Abstract

Abstract Background: The prognosis of small cell neuroendocrine carcinoma of the uterine cervix (SCNECC) is extremely poor due to the aggressive natural history. Since it is a rare cancer, there are few studies describing its molecular biology. Small cell lung cancer (SCLC) accounts for 95% of small cell carcinomas, therefore, clinically the chemotherapy regimens used for SCNECC have been based on regimens used for SCLC. This study aims to detect therapeutic targets for SCNECC by taking clues from the molecular biological commonalities between SCNECC and SCLC. Methods: We analyzed protein expression of cancer tissue-originated spheroids from lung and cervical cancers using isobaric tags for relative and absolute quantitation (iTRAQ). In vitro, protein expression levels of VRK1 in SCNECC cell lines (TC-YIK and HCSC-1), SCLC cell lines (SBC3 and OS2RA) and cell lines of mucinous adenocarcinoma and squamous cell carcinoma of the uterine cervix (HeLa and ME180) were assessed by western blotting (WB), and the change of cell proliferation induced by siRNA/shRNA-mediated VRK1 knockdown was assessed by WST-8 assay. In vivo, in mice xenograft models of SCNEC, the change of tumor size due to downregulation of VRK1 by shRNA were assessed. Furthermore, to explore the possible role of VRK1 in small carcinoma, pathway enrichment and ontology analysis between VRK1-high and -low-SCLC was performed by Gene Set Enrichment Analysis (GSEA), and it was compared with RNA-seq results of between shRNA-mediated VRK1 knockdown and control SCNECC cell lines. Results: iTRAQ showed that SCNECC and SCLC revealed similar protein expression profiles, rather than organ of origin-specific patterns. In addition, higher expression of VRK1 was detected in small cell carcinomas compared to the others. (SCLC/mucinous adenocarcinoma of the lung=2.86, SCNECC/mucinous adenocarcinoma of the cervix=2.56, SCNECC/squamous cell carcinoma of the cervix=2.17). WB showed that all SCNECC and SCLC cell lines expressed more highly VRK1 than other cervical cancer cell lines. In vitro, siRNA/shRNA-mediated VRK1 knockdown significantly suppressed the cell proliferation of SCNECC and SCLC (-29.0±0.3% in SBC-3 and -33.1±6.7% in TC-YIK, p<0.05, other cell lines were comparable). In vivo, the downregulation of VRK1 significantly suppressed tumor size in mice xenograft models of SCNEC (1726±442mm3 vs 544±233mm3 in TC-YIK, p<0.05, HCSC-1 was comparable). GSEA showed that VRK1 might participate in DNA repair to affect the biological process of SCLC, and the genes contained in this gene set was also detected in RNA-seq of SCNEC, suggesting involvement with VRK1. Conclusion: These findings suggest that VRK1 is involved in the proliferation of SCNECC in relation to DNA repair pathways. Our ongoing research is investigating the functional relationship between VRK1 and genes related to DNA repair and its effect on proliferation of SCNECC in vitro. Citation Format: Mariya Kobayashi, Satoshi Nakagawa, Yuji Kamei, Tatsuo Masuda, Mamoru Kakuda, Kosuke Hiramatsu, Ai Miyoshi, Tomomi Takata, Toshihiro Kimura, Eiji Kobayashi, Yutaka Ueda, Tadashi Kimura. Knockdown of VRK1 inhibits the proliferation of small cell neuroendocrine carcinoma of the uterine cervix [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 327.