A novel cancer-germline gene DAZL promotes progression and cisplatin resistance of non-small cell lung cancer by upregulating JAK2 and MCM8

Abstract

Germline-specific genes are usually activated in cancer cells and drive cancer progression; such genes are called cancer-germline or cancer-testis genes. The RNA-binding protein DAZL is predominantly expressed in germ cells and plays a role in gametogenesis as a translational activator or repressor. However, its expression and role in non-small cell lung cancer (NSCLC) are unknown. Here, mining of RNA-sequencing data from public resources and immunohistochemical analysis of tissue microarrays showed that DAZL was expressed exclusively in testis among normal human tissues but ectopically expressed in NSCLC tissues. Testis and NSCLC cells expressed the shorter and longer transcript variants of the DAZL gene, respectively. Overexpression of the longer DAZL transcript promoted tumor growth in a mouse xenograft model. Silencing of DAZL suppressed cell proliferation, colony formation, migration, invasion, and cisplatin resistance in vitro and tumor growth in vivo. Quantitative proteomic analysis based on tandem mass tag and Western blot analysis showed that DAZL upregulated the expression of JAK2 and MCM8. RNA-binding protein immunoprecipitation assays showed that DAZL bound to the mRNA of JAK2 and MCM8. The JAK2 inhibitor fedratinib attenuated the oncogenic outcomes induced by DAZL overexpression, whereas silencing MCM8 counteracted the effects of DAZL overexpression on cisplatin-damaged DNA synthesis and half-maximal inhibitory concentration of cisplatin. In conclusion, DAZL was identified as a novel cancer-germline gene that enhances the translation of JAK2 and MCM8 to promote NSCLC progression and resistance to cisplatin, respectively. These findings suggest that DAZL is a potential therapeutic target in NSCLC.

Keywords: Cancer-germline gene; Deleted in azoospermia like (DAZL); Janus kinase 2 (JAK2); Lung cancer; Minichromosome maintenance 8 (MCM8).