CHI3L1 promotes proliferation and improves sensitivity to cetuximab in colon cancer cells by down-regulating p53

Abstract

Background: Chitinase 3-like protein 1 (CHI3L1) is most likely a malignant tumor metastasis-associated gene. However, the functions of CHI3L1 in colon cancer cell proliferation and its cetuximab sensitivity are still unclear. We aimed to investigate the mechanism of CHI3L1 in promoting colon cancer cell proliferation and its sensitivity to cetuximab.

Methods: The expression of CHI3L1 in colon cancer and adjacent tissues were detected by immunohistochemistry. CHI3L1 was overexpressed in colon cancer cell lines by lentiviral technology. Cell proliferation and sensitivity to cetuximab were measured by MTT assay, cell cycle was analyzed by flow cytometry, and expression of cell cycle-related proteins was analyzed by immunoblotting.

Results: The results showed that the level of CHI3L1 in colon cancer tissue was significantly higher than that in adjacent tissue, which was also correlated with overall survival. The cell proliferation rate was significantly increased after overexpression of CHI3L1, and the sensitivity to cetuximab was significantly increased. The expression of p53 was down-regulated while the EGFR was up-regulated significantly in CHI3L1 overexpressed cells. When rescued the expression of p53 in HCT116-CHI3L1 cells, the cell proliferation and sensitivity to cetuximab could be restored.

Conclusion: High levels of CHI3L1 are associated with poor prognosis and accelerate the proliferation of colon cancer cells and increase the sensitivity to cetuximab. Its mechanism of increasing the cell proliferation and sensitivity to cetuximab may be explained by down-regulating p53 expression and then, up-regulating the expression of EGFR.

Keywords: CHI3L1; cetuximab; colon cancer; p53; proliferation.

Figure 1

Chitinase 3‐like protein 1 (CHI3L1) expression was associated with overall survival in patients with CC. A, The UCSC Xena platform cohort analysis of the differentially expressed levels of CHI3L1 in the total CC samples as well as in the pair‐matched tumor tissues. B, IHC analysis of the expression level and cellular localization of CHI3L1 in CC tissue cells. C, qPCR analysis of the mRNA expression level of CHI3L1 in CC cell lines. D, Kaplan‐Meier analysis of the association of CHI3L1 high or low expression with the overall survival of the patients with CC.*, P < .05

Figure 2

The infection efficiency of Chitinase 3‐like protein 1 (CHI3L1) in SW620 and HCT116 cells. A, The fluorescent intensity of CC cells after infection for 48 h; Left: green fluorescence field; Right: bright field merged with green fluorescence field. B, CHI3L1 mRNA expression and C, Protein expression in different groups. Three replicates were set for each group in qPCR assay. *, P < .05

Figure 3

Effect of Chitinase 3‐like protein 1 (CHI3L1) overexpression on cell proliferation and drug sensitivity. A, CHI3L1 overexpression promotes cell proliferation. B, The inhibition rates of SW620 and HCT116 cells after treatment with different concentrations of cetuximab. C, The sensitivity of cells to cetuximab (1mg/ml) increased after the addition of different concentrations of exogenous CHI3L1. D, Effect of cetuximab on cell cycle after overexpression of CHI3L1. E, Proportion of each phase of the cell cycle. *, P < .05, in HCT116 group; ^△, P < .05, in SW620 group

Figure 4

Mechanism of Chitinase 3‐like protein 1 (CHI3L1) overexpression affecting cell sensitivity to cetuximab. A, The expression of EGFR and p53 in HCT116‐pCDH and HCT116‐CHI3L1 cells after treatment with cetuximab. B, The expression of EGFR and p53 in SW620‐pCDH and SW620‐CHI3L1 cells after treatment with cetuximab. C, The expression level of EGFR and p53 after transfection of p53 overexpression plasmid in HCT116‐CHI3L1 cells. D, p53 overexpression inhibited cell proliferation. E, Overexpression of p53 decreased the sensitivity of HCT116‐pCDH cell to cetuximab. *, P < .05, in CHI3L1 group; ^△, P < .05, in pCDH group