High expression of DTX2 promotes proliferation, invasion and epithelial-mesenchymal transition of oxaliplatin-resistant colorectal cancer cells

doi:10.12122/j.issn.1673-4254.2025.04.18

Abstract

Abstract:

Objective To investigate the role of DTX2 in regulating biological behaviors of oxaliplatin-resistant colorectal cancer cells (CRC/OXA cells). Methods CCK8 assay was used to determine the inhibition rate of oxaliplatin-treated CRC cells. A CRC/OXA cell line was constructed, in which DTX2 expression level was detected. The cells were transfected with a DTX2-shRNA plasmid or co-transfected with DTX2-shRNA and pcDNA-Notch2, and the changes in cell proliferation, migration and invasion ability were evaluated using plate cloning assay, scratch assay and Transwell invasion assay. The expression levels of Notch2, NICD and epithelial-mesenchymal transition (EMT) proteins of the transfected cells were detected with Western blotting. In a nude mouse model bearing SW620/OXA cell xenografts, the effects of DTX2 knockdown and Notch2 overexpression in the implanted cells on tumor growth and protein expressions were tested. Results The IC₅₀ of oxaliplatin was 6.00 μmol/L in SW620 cells and 8.00 μmol/L in LoVo cells. CRC/OXA cells showed a significantly increased expression of DTX2. DTX2 knockdown in CRC/OXA cells significantly inhibited cell proliferation, migration and invasion, and these effects were reversed by co-transfection of the cells with pcDNA-Notch2. DTX2 knockdown significantly reduced the expression levels of Notch2, NICD and vimentin proteins and increased E-cadherin expression in CRC/OXA cells, and co-transfection with pcDNA-Notch2 potently attenuated the changes in these proteins. In the tumor-bearing mice, DTX2 overexpression obviously promoted the growth of SW620/OXA cell xenograft, enhanced the protein expressions of Notch2, NICD and vimentin, and lowered the expression of E-cadherin. Conclusion High expression of DTX2 promotes proliferation, migration, invasion and EMT of CRC/OXA cells through the Notch2 signaling pathway, suggesting the potential of DTX2 as a target to improve the efficacy of oxaliplatin.

Key words: deltex-2, colorectal cancer, Nohch2 signaling pathway, epithelial-mesenchymal transition, oxaliplatin resistance

Zhennan MA, Fuquan LIU, Xuefeng ZHAO, Xiaowei ZHANG. High expression of DTX2 promotes proliferation, invasion and epithelial-mesenchymal transition of oxaliplatin-resistant colorectal cancer cells[J]. Journal of Southern Medical University, 2025, 45(4): 829-836.

Figures/Tables 8

Fig.1 IC50 of oxaliplatin in SW620 cells (6.00 μmol/L) and LoVo cells (8.00 μmol/L).

Fig 2 Western blotting for detecting protein expressions of DTX2 (A) and its relative protein (B) and mRNA (C) expression levels in CRC and CRC/OXA cells. SW620/OXA: Oxaliplatin-resistant SW620 cells; LoVo /OXA: Oxaliplatin-resistant LoVo cell. *P<0.01.

Fig.3 Plate cloning assays showing the proliferation capacity of CRC/OXA cells after transfection with DTX2-shRNA and DTX2-shRNA+pcDNA-Notch2 (A) and the mean number of colonies formed (B). *P<0.05.

Fig.4 Scratch assay for assessing changes of migration ability of SW620/OXA (A, B) and LoVo/OXA (C, D) cells after transfection with DTX2-shRNA and DTX2-shRNA+pcDNA-Notch2. *P<0.05.

Fig.5 Transwell invasion assay for assessing changes of migration ability of SW620/OXA and LoVo/OXA cells after transfection with DTX2-shRNA and DTX2-shRNA+pcDNA-Notch2. A: Microscopic observation of the cells (Original magnification: ×100). B: Average number of invasive cells in different groups. *P<0.01.

Fig.6 Changes of protein expressions in the Notch2 Signal pathway and EMT in SW620 and LoVo cells co-transfected with DTX2-shRNA and DTX2-shRNA+pcDNA-Notch2. A, C: Western blots of the proteins in SW620/OXA and LoVo/OXA cells. B, D: Quantitative analysis of the protein expressions. GAPDH was used as the internal control. *P<0.01.

Fig.7 Growth of SW620/OXA cell xenografts transfected with DTX2-shRNA or DTX2-shRNA+pcDNA-Notch2 in nude mice. A: Observation of the tumor-bearing mice and the dissected tumors. B: Changes in the volume of the xenografts over time. C: Xenograft weight measurement. *P<0.05.

Fig.8 Protein expressions in SW620/OXA cell xenografts transfected with DTX2-shRNA or DTX2-shRNA+pcDNA-Notch2. A: Western blotting of the proteins in SW620/OXA cell xenografts. B: Quantitative analysis of the protein expressions. GAPDH was used as the internal control. *P<0.01.

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