Impact of LIN7A silencing on U87 cell invasion and its clinical significance in glioblastoma.

Abstract

Glioblastoma is highly aggressive and resistant to treatment, making it crucial to understand the regulatory mechanisms underlying its invasion. LIN7A, a polar protein, has been implicated in tumor cell migration and invasion, but its role in glioblastoma remains unclear. This study aimed to manipulate LIN7A gene expression in U87 cells, analyze its impact on invasion, and explore the potential mechanisms through which LIN7A regulates glioblastoma cell invasion. Lentiviral vectors were used to silence the LIN7A gene in U87 cells, selecting the most effective vector. LIN7A gene transcription, protein expression and localization were analyzed using RT-qPCR, Western blotting, and immunofluorescence. U87 cell invasion was assessed via real-time cell analysis and spheroid invasion assay, while MMP-2 and MMP-9 protease activities were measured using zymography. β-catenin protein levels and localization were evaluated through Western blotting and immunofluorescence. Expression of target genes in the β-catenin pathway was also measured. An orthotopic xenograft glioblastoma model in nude mice was established by intracranial implantation of U87 cells, with tumor growth monitored using immunofluorescence analysis of brain slices. The clinical significance of LIN7A expression was confirmed by comparing its levels in core and peripheral invading areas of glioblastoma and analyzing RNASeq data and clinical information from the Clinical Proteomic Tumor Analysis Consortium (CPTAC) GBM cohort. Transfection of U87 cells with a lentiviral vector led to decreased LIN7A levels and altered distribution patterns. Silencing the LIN7A gene increased U87 cell proliferation and invasiveness, reduced clonal formation ability, and enhanced MMP-2 and MMP-9 protease activity. It also resulted in a slight increase in cytoplasmic β-catenin content, although not statistically significant, but a significant increase in nuclear β-catenin accumulation and transcriptional activity of target genes in the pathway. Animal studies showed that LIN7A gene silencing caused U87 cells to transition from clumpy to invasive growth mode. LIN7A expression was significantly lower in the peripheral invading area compared to the core area in clinical samples of glioblastoma. Data mining of the CPTAC-GBM cohort revealed a strong association between LIN7A gene expression and survival time. Silencing LIN7A may promote U87 tumor cell invasion by disrupting intercellular junctions, altering cell polarity, and activating the β-catenin pathway. Further research is warranted to elucidate the role of LIN7A in glioblastoma cell invasion.