The germline factor DDX4 contributes to the chemoresistance of small cell lung cancer cells

DDX4, a conserved germline factor and RNA helicase, increases small cell lung cancer cell survival by regulating DNA damage and immune response pathways and contributes to cisplatin-mediated drug resistance. Human cancers often re-express germline factors, yet their mechanistic role in oncogenesis and cancer progression remains unknown. Here we demonstrate that DEAD-box helicase 4 (DDX4), a germline factor and RNA helicase conserved in all multicellular organisms, contributes to increased cell motility and cisplatin-mediated drug resistance in small cell lung cancer (SCLC) cells. Proteomic analysis suggests that DDX4 expression upregulates proteins related to DNA repair and immune/inflammatory response. Consistent with these trends in cell lines, DDX4 depletion compromised in vivo tumor development while its overexpression enhanced tumor growth even after cisplatin treatment in nude mice. Further, the relatively higher DDX4 expression in SCLC patients correlates with decreased survival and shows increased expression of immune/inflammatory response markers. Taken together, we propose that DDX4 increases SCLC cell survival, by increasing the DNA damage and immune response pathways, especially under challenging conditions such as cisplatin treatment.

Automated summary

DDX4, a conserved germline factor and RNA helicase, promotes small cell lung cancer cell survival by regulating DNA damage and immune response pathways, and contributes to cisplatin-mediated drug resistance. Proteomic analysis suggests that DDX4 expression upregulates proteins related to DNA repair and immune/inflammatory response. The relatively higher DDX4 expression in SCLC patients correlates with decreased survival and increased expression of immune/inflammatory response markers. Thus, DDX4 may be an important therapeutic target in SCLC.