PSPC1 knockout promotes radiosensitivity, inhibits EMT, and metastasis of nasopharyngeal carcinoma cells

Abstract

Purpose: Paraspeckle component 1 (PSPC1) is upregulated in numerous cancers and is associated with reduced patient survival rates. Our previous research indicated that elevated PSPC1 levels in nasopharyngeal carcinoma (NPC) are positively linked to radiation resistance and tumor metastasis, two primary clinical challenges in NPC treatment. However, the precise role of PSPC1 in radiation resistance and metastasis of NPC cells remains unclear. This study aimed to explore the molecular mechanisms by which PSPC1 influences radiation resistance and metastasis in NPC.

Methods: Using the radiation-resistant R743 and radiosensitive CNE2 cell lines of NPC, we examined the impact of PSPC1 expression on post-radiation survival, cell cycle progression, apoptosis, migration, invasion, and tumor growth. CRISPR/Cas9 genome editing was employed to generate PSPC1 knockout (KO) lines in R743 cells, while PSPC1 overexpression (pcD-PSPC1) was achieved in CNE2 cells via pcDNA3.1(+)-PSPC1 plasmid transfection.

Results: PSPC1 knockout converted R743 cells from radioresistant to radiosensitive, whereas PSPC1 overexpression decreased radiosensitivity in CNE2 cells. Cell cycle analysis revealed that PSPC1 KO arrested R743 cells in the G2/M phase post-irradiation, while PSPC1 overexpression prevented G2/M phase arrest in CNE2 cells. PSPC1 KO increased irradiation-induced apoptosis in R743 cells, whereas PSPC1 overexpression decreased it in CNE2 cells. Post-radiation, PSPC1 KO cells showed significantly reduced migration and invasion abilities. Bioinformatics analysis identified SFPQ as a PSPC1-interacting protein, with PSPC1 KO resulting in SFPQ downregulation. Additionally, PSPC1 KO enhanced the radiosensitivity of xenografted tumors in nude mice.

Conclusion: Our findings suggest that PSPC1 is a pivotal factor in enhancing the survival and spread of NPC cells post-radiation. Targeting PSPC1 or its downstream pathways could offer novel strategies to overcome radiation resistance and metastasis in NPC cells.

Keywords: Cell cycle; Metastasis; Nasopharyngeal carcinoma; PSPC1; Radiosensitivity.