VRK1 Is a Novel Therapeutic Target for Small Cell Neuroendocrine Carcinoma of the Cervix

Small cell neuroendocrine carcinoma of the cervix (SCNEC) is classified as a high-grade neuroendocrine carcinoma with a worse prognosis than other major histological types of cervical cancer. Identifying novel therapeutic targets based on its molecular characteristics is highly desirable but challenging due to the rarity of SCNEC and the resulting lack of research resources. In this study, we identified vaccinia-related kinase 1 (VRK1) as a potential therapeutic target for SCNEC. VRK1 was prioritized based on our previously reported proteomic analysis of patient-derived organoids. Immunohistochemistry of patient samples consistently revealed high VRK1 expression in SCNEC, as opposed to its variable expression in other cervical carcinomas. Although VRK1 knockdown in SCNEC had only a limited effect on cell proliferation in two-dimensional cultures, it significantly suppressed cell proliferation in three-dimensional cultures and inhibited xenograft tumor growth in vivo. Gene set enrichment analysis of RNA-sequencing data from mouse xenograft models demonstrated that VRK1 is associated with mitochondrial-related pathways. Furthermore, under oxidative stress conditions, VRK1 knockdown resulted in a reduction of mitochondrial membrane potential, an indicator of mitochondrial integrity, and decreased expression of cytochrome c oxidase subunit IV (COX IV), a nuclear-encoded subunit of cytochrome c oxidase, the terminal enzyme complex of the mitochondrial respiratory chain. These findings suggest that VRK1 knockdown indirectly impaired mitochondrial function. Collectively, these anti-tumor effects highlight VRK1 as a promising therapeutic target for SCNEC.