Hypoxia-inducible lipid droplet-associated (HILPDA) facilitates the malignant phenotype of lung adenocarcinoma cells in vitro through modulating cell cycle pathways

Abstract Background Hypoxia-inducible lipid droplet-associated (HILPDA) is considered to have tumorigenic activity, but its function in lung adenocarcinoma (LUAD) is rarely known. This work aimed to assess the regulatory functions as well as the in-depth mechanism of HILPDA in LUAD. Methods The expression of HILPDA in LUAD tissues was analyzed based on TCGA database, and then qRT-PCR was performed to confirm the HILPDA expression in LUAD cell lines. Kaplan-Meier analysis was used to measure the correlation of HILPDA expression and overall survival in patients with LUAD. Then, Cell-Counting Kit-8 (CCK-8), colony formation and transwell assays were performed to detect cell proliferation, invasion and migration. Moreover, the pathways closely related to the high HILPDA expression was analyzed by Kyoto Encyclopedia of genes and Genomes (KEGG) analysis. The levels of Cell cycle pathway-related proteins were assessed using western blotting. Results Herein, we revealed that HILPDA was expressed at high levels in LUAD tissues and cell lines, and LUAD patients with the higher HILPDA expression presented the shorter survival time. Down-regulation of HILPDA in Calu-3 cells can retard cell proliferation, migration and invasion as well as arrest cells in the G1 phase, whereas overexpression of HILPDA in A549 cells presented a marked promotion on these phenotypes. Moreover, we surveyed that knockdown of HILPDA restrained the activation of cell cycle pathway, while up-regulation of HILPDA led to opponent outcomes. Conclusions In summing, HILPDA may act as an oncogenic factor in LUAD cells via modulating cell cycle pathway, which represent a novel biomarker of tumorigenesis in LUAD patients.