LncRNA PART1 promotes lung squamous cell carcinoma progression via miR-185-5p/Six1 axis

Dysregulation of the long non-coding RNA prostate androgen regulated transcript 1 (lncRNA PART1) is involved in the tumorigenesis of various cancers. However, little is known about its function and molecular mechanism in the development of lung squamous cell carcinoma (LSCC). In this study, we examined the expression of PART1 in LSCC clinical tissue samples and cell lines, and gain- and loss-of-function experiments were performed to explore the function of PART1 in LSCC proliferation, invasion and migration. We found that PART1 was overexpressed in both LSCC tissues and cell lines. Functional studies revealed that PART1 knockdown significantly suppressed cell proliferation, invasion and migration but enhanced apoptosis in LSCC cells, whereas overexpression of PART1 showed the opposite results. Mechanistically, we identified that PART1 acted as a sponge of miR-185-5p, and sineoculis homeobox homolog 1 (Six1) was a direct downstream target of miR-185-5p. Moreover, restoration of miR-185-5p or silencing of Six1 partially abolished the oncogenic effect of PART1 in LSCC cells. Clinically, The areas under the receiver operating characteristic (ROC) curve of PART1, miR-185-5p, and Six1 were 0.7857, 0.7332, 0.8112, respectively. Notably, high PART1, low miR-185-5p, and high Six1 expressions were significantly associated with severe clinical parameters and were the independent risk factors for poor prognosis of LSCC patients. Thus, we concluded that the PART1/miR-185-5p/Six1 axis might serve as a novel biomarker for the diagnosis and treatment of LSCC.