CircSMARCA5 inhibits glycolysis and suppresses proliferation and invasion of gastric cancer cells through miR-4295/PTEN axis

doi:10.19401/j.cnki.1007-3639.2022.04.002

Abstract

Abstract:

Background and purpose: Gastric cancer is one of the most common malignant tumors of digestive system. Previous study demonstrated that circSMARCA5 was downregulated and could function as a tumor suppressor in gastric cancer. However, the molecular mechanism has not yet been documented. This study aimed to investigate the effects of circSMARCA5 on the proliferation and invasion of gastric cancer cells and their molecular mechanisms. Methods: Cell counting kit-8 (CCK-8) assays and transwell assays were performed to examine the cell proliferative and invasive abilities, respectively. The effect of circSMARCA5 on gastric cancer cell glycolysis was assessed by detecting the extracellular acidification rate, glucose uptake level and lactate production. Real-time fluorescent quantitative polymerase chain reaction (RTFQ-PCR) assay was performed to detect the expression levels of circSMARCA5, miR-4295 and PTEN. The levels of GLUT1 and LDHA were measured by Western blot assay. The transplanted xenograft model in nude mice was established, and the effects of circSMARCA5 on the tumor growth were observed. Immunohistochemistry assays were performed to examine the expression levels of GLUT1, LDHA and Ki-67 proliferation index in xenograft tumors. Dual luciferase reporter gene assays, Pearson's correlation analysis and RNA immunoprecipitation (RIP) assays were used to confirm the targeting relationship of circSMARCA5 and miR-4295 as well as miR-4295 and PTEN. Results: CircSMARCA5 overexpression inhibited the proliferation and invasion of gastric cancer cells. Compared to the control group, the glycolysis rate, glycolysis capacity, glucose uptake and lactate production in the circSMARCA5-overexpresing group were significantly decreased. In addition, nude mouse transplanted xenograft assays showed that the volume and the weight of the tumors in the circSMARCA5-overexpressing group were lower compared with the control group. Further studies indicated that circSMARCA5 acted as a molecular sponge to inhibit the expression of miR-4295. Besides, miR-4295 could inhibit the expression of PTEN by binding with the 3'-UTR of PTEN mRNA. Rescue experiments by upregulating miR-4295 or downregulating PTEN expression in the circSMARCA5-overexpressing gastric cancer cells were performed, and the results showed that upregulation of miR-4295 or PTEN knockdown could abolish the inhibitory effects of circSMARCA5 overexpression on cell proliferation, invasion and glycolysis. Conclusion: CircSMARCA5 suppresses the proliferation and invasion of gastric cancer cells by targeting miR-4295, increasing the expression level of PTEN and subsequently regulating glycolysis.

Key words: Stomach neoplasms, Circular RNA, miR-4295, PTEN, Glycolysis, Invasion

CLC Number:

R735.2

CAI Juan, CHEN Zhiqiang, ZUO Xueliang. CircSMARCA5 inhibits glycolysis and suppresses proliferation and invasion of gastric cancer cells through miR-4295/PTEN axis[J]. China Oncology, 2022, 32(4): 298-308.

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Clinicopathological features	Case n (%)	Clinicopathological features	Case n (%)
Age/year		Lymph node metastasis
<60	21 (35.0)	Negative	22 (36.7)
≥60	39 (65.0)	Positive	38 (63.3)
Gender		Vascular invasion
Female	16 (26.7)	No	29 (48.3)
Male	44 (73.3)	Yes	31 (51.7)
Tumor size D/cm		TNM staging
<5	41 (68.3)	Ⅰ/Ⅱ	24 (40.0)
≥5	19 (31.7)	Ⅲ	36 (60.0)
Differentiation
Well/Moderate	28 (46.7)
Poor	32 (53.3)