Analysis and exploration of regulatory mechanisms and potential prognostic biomarkers in squamous cell carcinoma of the lung by expression profiling.

Abstract

Background: Lung cancer is the most common malignant tumor in China. In 2016, more than 800,000 new cases of lung cancer were diagnosed in China. Squamous cell carcinoma of the lung, a type of non-small cell lung cancer (NSCLC), accounts for 25-30% of all lung cancer cases, and has an overall 5-year survival rate of about 32.53%, lower than adenocarcinoma for which there have been far more therapeutic advances in the last few decades. The purpose of this study was to explore the mechanisms of the disease and to identify potential prognostic biomarkers.

Methods: This study analyzed lung squamous cell carcinoma of the lung tissues and paraneoplastic tissues to identify differentially expressed genes (DEGs). We conducted a Gene Set Enrichment Analysis and prognostic analysis by constructing competing endogenous RNA (ceRNA) networks; we performed a correlation analysis of the target genes and verified the targeting relationship of the ceRNA by cellular assays. We assessed the effects of the target genes on tumor cell proliferation, invasion and apoptosis by Cell Counting Kit-8 (CCK-8) assays, invasion assays, and caspase 3/7 assays, respectively.

Results: We identified 4,039 downregulated genes and 1,924 upregulated genes. The p53 pathway, cell-cycle pathway and mismatch-repair (MMR) pathway were activated, while the mitogen-activated protein kinase pathway was inhibited. Two ceRNA networks centered on the long non-coding RNAs (lncRNAs) MAGI2-AS3 and LINC01089 were constructed. MAGI2-AS3 was found to regulate five messenger RNAs (mRNAs) (i.e., MBNL2, ATP5L, FAM103A1, MDH1, and STXBP1) through three microRNAs (miRNAs), whereas LINC01089 was found to regulate six mRNAs (i.e., ZFP36L2, APBB2, PDLIM3, MYADM, PHF5A, and SLC26A9) through two miRNAs. The expression of these lncRNAs and mRNAs was significantly associated with prognosis (P<0.05). A significant correlation was also found between the expression of MAGI2-AS3 and MBNL2 (R=0.51), and both signatures were also significantly associated with prognosis. We also found that MAGI2-AS3 and MBNL2 had a regulatory relationship at the cellular level, for example, high expression of MBNL2 was noted to inhibit cancer cell proliferation and migration yet promote apoptosis.

Conclusions: MAGI-AS3 and MBNL2 are both differentially expressed in squamous cell carcinoma of the lung and are potential prognostic markers. A significant association was also found between MAGI2-AS3 and the expression of MBNL2 (R=0.51). High expression of MBNL2 inhibits cancer cell proliferation and migration, yet promotes cancer cell apoptosis.