Ubc9 promotes invasion and metastasis of lung cancer cells.

Lung cancer is the leading cause of cancer-related mortality worldwide. The mortality is high mainly due to the lack of known effective screening procedures; there is a high tendency for early spread and systemic therapies do not cure metastatic disease. Thus, it is important to investigate the molecular mechanism(s) of lung cancer development and, specifically, to identify an effective method by which to inhibit the invasion and metastasis of lung cancer. Ubiquitin-conjugating enzyme 9 (Ubc9), the sole conjugating enzyme for sumoylation, regulates protein function and plays a key role in tumorigenesis. Whether Ubc9 is involved in the invasion and metastasis of lung cancer remains unknown. Herein, we report that Ubc9 exhibits an important role in lung cancer invasion and metastasis. We first investigated the biological effect of Ubc9 on lung cancer by cloning the Ubc9 gene into a eukaryotic expression plasmid and stably expressing it in the human small cell lung cancer cell line NCI-H446 in order to observe any biological changes. We further analyzed the effect of Ubc9 in an in vivo experiment, injecting NCI-H446 cells stably overexpressing Ubc9 into nude mice and analyzing their metastatic ability. Our results demonstrated that Ubc9 is expressed at higher levels in primary lung cancer tissue and metastatic nodules as compared to premalignant and/or normal tissue. Furthermore, we demonstrated that upregulation of Ubc9 expression promotes migration and invasion. Ubc9 likely plays an important role in cancer progression by promoting invasion and metastasis in lung cancer.