SERPINA5 promotes tumour cell proliferation by modulating the PI3K/AKT/mTOR signalling pathway in gastric cancer

Abstract

SERPINA5 belongs to the serine protease inhibitor superfamily and has been reported to be lowly expressed in a variety of malignancies. However, few report of SERPINA5 in gastric cancer has been found. The purpose of this study was to determine the role of SERPINA5 in GC and to investigate potential tumorigenic mechanisms. We performed qPCR to determine the level of SERPINA5 expression in GC. We used public databases to evaluate whether SERPINA5 could be utilized to predict overall survival and disease-free survival in GC patients. We also knocked down the expression of SERPINA5 and evaluated its effect on cell proliferation and migration. Furthermore, we explored the signal pathways and regulatory mechanisms related to SERPINA5 functions. According to our findings, SERPINA5 was shown to exhibit high expression in GC. Notably, SERPINA5 was prognostic in GC with high expression being unfavourable. SERPINA5 was further observed to promote GC tumorigenesis by modulating GC cell proliferation ability. Mechanically, SERPINA5 could inhibit CBL to regulate the PI3K/AKT/mTOR signalling pathway, thereby promoting GC carcinogenesis progression. These results highlight the important role of SERPINA5 in GC cell proliferation and suggest that SERPINA5 could be a novel target for GC treatment and a predictor for GC prognosis.

Keywords: SERPINA5; cell proliferation; gastric cancer; signal regulation; tumour therapy.

FIGURE 1

Up‐regulation of SERPINA5 is correlated with poor prognosis in GC. Kaplan–Meier survival curves showing the effect of SERPINA5 expression on (A) overall survival rates and (B) disease‐free survival rate in patients with GC. (C): SERPINA5 expression in 17 paired human gastric cancer and adjacent normal tissues. (D): Expression of SERPINA5 in normal GES‐1 cells and three gastric cancer cell lines. *p < 0.05, **p < 0.01, ***p < 0.001

FIGURE 2

SERPINA5 knockdown inhibits cell viability and proliferation. Expression of SERPINA5 in si‐CON and si‐SERPINA5 transfected (A) MKN‐28 and (B) BGC‐823 cells. MTT assay showing the viability of (C) MKN‐28 and (D) BGC‐823 cells transfected with si‐CON or si‐SERPINA5. Representative results of colony formation in (E) MKN‐28 and (F) BGC‐823 cells, respectively. *p < 0.05, **p < 0.01, ***p < 0.001

FIGURE 3

SERPINA5 knockdown induces G0/G1 phase arrest and promotes apoptosis in GC cell lines. Cell cycle distribution of si‐CON and si‐SERPINA5 transfected (A) MKN‐28 and (B) BGC‐823 cells as determined by flow cytometry. Cell apoptosis detection of si‐CON and si‐SERPINA5 transfected (C) MKN‐28 and (D) BGC‐823 cells as determined by flow cytometry. Western blot analysis showing the expression of cell apoptosis and cycle‐related proteins in si‐CON or si‐SERPINA5 transfected (E) MKN‐28 and (F) BGC‐823 cells. *p < 0.05, **p < 0.01, ***p < 0.001

FIGURE 4

SERPINA5 regulates PI3K/AKT/mTOR signalling pathway through inhibiting CBL. (A) The interaction between SERPINA5 and CBL was showed by GeneMANIA online software. (B) The decreased expression of CBL in GC cell lines both in mRNA and protein levels. (C) The upregulated expression of CBL after silencing SERPINA5 in MKN‐28 cell lines (D) CO‐IP was performed to confirm the interaction between SERPINA5 and CBL in MKN‐28 cell lines. Western blot analysis showing that CBL negatively regulates PI3K/AKT signalling pathway in (E) MKN‐28 and (F) BGC‐823 cells. (G) Knockdown of SERPINA5 can inhibit the PI3K/AKT pathway. (H) The novel mechanism by which high expressed SERPINA5 induces GC progression. *p < 0.05, **p < 0.01, ***p < 0.001