Abstract 5686: Revealing the unique malignant mechanism of gastric-type adenocarcinoma of the cervix

Abstract Objective: Gastric-type adenocarcinoma of the cervix (GAS) is an HPV-independent malignancy that accounts for 20-25 % of cervical adenocarcinomas. Compared to usual-type endocervical adenocarcinoma (UEA), GAS is resistant to chemotherapy and radiotherapy, and has a poor prognosis. However, its molecular biological mechanisms remain unclear. This study aimed to identify specific RNA profiles associated with GAS pathophysiology to discover diagnostic and therapeutic targets. Methods: We examined 15 tumor samples from patients who underwent primary hysterectomy (7 GAS, 8 UEA). From FFPE specimens, only the tumor region was obtained, and miRNA-seq and mRNA-seq were performed. RNA was also extracted from the GAS-derived KGAS cell line, UEA-derived HCA-1 cell line, and normal cervical epithelial HCK1T cell line for miRNA-seq. Extracellular vesicles (EVs) from each cell line were collected, and miRNA-seq was performed by using EV-RNA. Detail functional analyses were performed using cell lines. Results: miRNA sequencing of FFPE samples, cell lines, and EVs derived from GAS and UEA identified 48 miRNAs highly expressed in GAS tissue, 37 in GAS cell lines, and 41 in GAS-EVs. Further target exploration revealed one miRNA specifically highly expressed in GAS. Additionally, mRNA sequencing analysis of tumor tissue samples with 10 cases (5 GAS, 5 UEA) identified a total of 14, 541 genes, and clustering analysis showed that GAS and UEA had clearly distinct expression profiles. Differential expression analysis identified 449 upregulated genes in GAS and 577 downregulated genes in UEA, meeting the criteria of FC ≥ 1 and p-value < 0.05. Among these, the top 30 genes with the highest FC values and basemean ≥ 50 were selected. IPA and GSEA analyses significantly detected cancer-related pathways, including RTK-RAS-PI3K, PDGF signaling, and cell cycle-related pathways. The top 10 significant genes were validated by qRT-PCR, and protein expression was confirmed by immunohistochemistry. Functional validation in cell lines showed that GAS exhibited significantly higher cisplatin resistance (p < 0.05) than other cell lines, and suppression of newly identified specific target gene in GAS cells resulted in increasing sensitivity of cisplatin. Conclusion: This study revealed detailed miRNA and mRNA profiles of GAS and UEA, identifying GAS-specific miRNA and gene expression. Identified genes were confirmed as not only useful as disease markers but also functional targets. These findings contribute to understanding the unique malignant mechanisms of GAS and highlight promising targets for future therapeutic strategies. Citation Format: Hiroaki Yamada, Akira Yokoi, Kazuhiro Suzuki, Kosuke Yoshida, Eri Inami, Masami Kitagawa, Naotake Tsuda, Hiroaki Kajiyama. Revealing the unique malignant mechanism of gastric-type adenocarcinoma of the cervix [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5686.