LncRNA HOXA-AS2 Promotes Oral Squamous Cell Proliferation, Migration, and Invasion via Upregulating EZH2 as an Oncogene

Abstract

Oral squamous cell carcinoma (OSCC) is one of the most common types of cancer worldwide. Accumulating evidence has shown that long noncoding RNAs (lncRNAs) serve important roles in the development of OSCC. The purpose of this study was to investigate the biological function and underlying regulatory mechanism of lncRNA homeobox A cluster antisense RNA2 (HOXA-AS2) in OSCC. RT-qPCR was performed to analyze the HOXA-AS2 expressions in human immortalized oral epithelial cell (HIOEC) line, human OSCC cell lines, and plasma. The expression of HOXA-AS2 and enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2) in Tca-8113 cells were knocked down or overexpressed by transfection with shRNA-HOXA-AS2 or pcDNA-EZH2, respectively. The interaction between HOXA-AS2 and EZH2 was validated by RNA immunoprecipitation assay. In addition, cell proliferation was assessed by CCK-8 and EdU assays. Cell cycle distribution was analyzed by flow cytometry. Cell migration and invasion were detected using wound healing and Transwell assays, respectively. Apoptosis was detected by TUNEL staining. The protein expression levels of cell cycle and apoptosis-related proteins were measured by western blot analysis. Compared with HIOEC cells, HOXA-AS2 expression in OSCC cells was upregulated. HOXA-AS2 knockdown significantly inhibited Tca-8113 cell proliferation, blocked the cell cycle by arresting cells in the G0/G1 phase, promoted apoptosis, and suppressed migration and invasion. In addition, HOXA-AS2 was predicted to directly target EZH2 and positively regulate EZH2 expression. EZH2 overexpression could reverse the inhibitory effect of HOXA-AS2 knockdown on the proliferation, migration, and invasion of Tca-8113 cells. In summary, the findings suggested that HOXA-AS2 may inhibit cell proliferation, invasion, and migration, induce cell cycle arrest in the G0/G1 phase, and increase cell apoptosis by targeting EZH2. The research indicated that HOXA-AS2/EZH2 axis may play a key role in the development of OSCC.

LncRNA HOXA‑AS2 is a prognostic and clinicopathological predictor in patients with cancer: A meta‑analysis

“…As an oncogene, lncRNA HOXA-AS2 exhibits abnormally high expression in a wide array of solid and hematological malignancies, such as acute myeloid leukemia (AML) (10), gallbladder cancer (11) and glioma (12), promoting the progression of these cancer types. The mechanisms by which lncRNA HOXA-AS2 inhibits apoptosis and stimulates proliferation have been the most extensively studied (13)(14)(15), indicating that lncRNA HOXA-AS2 not only affects the proliferation, invasion and migration of cancer cells but is also closely related to patient prognosis. For instance, the upregulation of lncRNA HOXA-AS2 in AML (10) demonstrates its oncogenic role by interacting with the epigenetic inhibitor Enhancer of zeste homolog 2 (EZH2), subsequently repressing the expression of Large Tumor Suppressor 2 (LATS2).…”

Role of HOXA1-4 in the development of genetic and malignant diseases

“…Li et al demonstrated that HOXA-AS2 is highly expressed in CRC tissues compared to normal tissues, and its expression can serve as a predictor of poor prognosis in CRC patients [ 151 ]. The association between HOXA-AS2 and EZH2 has also been confirmed in PC [ 152 ], OSCC [ 153 ], acute myeloid leukemia (AML) [ 154 ], and glioma [ 155 ]. Furthermore, the downregulation of HOXA-AS2 induces cell apoptosis, arrests the cell cycle in the G1 phase, and inhibits metastasis and invasion in GBC [ 156 ].…”

Overexpression of lncRNA HOXA-AS2 promotes the progression of oral squamous cell carcinoma by mediating SNX5 expression

“…Some studies indicated that the expression of HOXA-AS2 was strikingly upregulated in many types of cancers, such as in non-small cell lung cancer, bladder cancer and pancreatic cancer [ 12 – 15 ]. In addition, it was found that HOXA-AS2 promoted OSCC progression by upregulating EZH2 [ 16 ] or inhibiting miR-567 expression [ 17 ]. But, a better understanding of the roles of HOXA-AS2 in OSCC remains to be further studied.…”