Tumor-secreted dentin sialophosphoprotein induces oxaliplatin resistance in colorectal cancer through an integrin αvβ3-dependent pathway

doi:10.12122/j.issn.1673-4254.2026.03.01

Abstract

Abstract:

Objective To determine whether dentin sialophosphoprotein (DSPP) modulates oxaliplatin efficacy for colorectal cancer (CRC) and explore the underlying integrin αvβ3-dependent mechanism. Methods Immunohistochemistry was used to compare the expression levels of DSPP between oxaliplatin-sensitive and oxaliplatin-resistant CRC tissues. The changes in oxaliplatin sensitivity in parental and oxaliplatin-resistant CRC cell lines after DSPP knockdown or overexpression were assessed using CCK-8 assay, and Western blotting was used to evaluate the efficacy of DSPP modulation and MAPK pathway activity. The interaction between DSPP and integrin αvβ3 was examined by immunofluorescence staining, co-immuno-precipitation, and immunohistochemistry. HE and immunofluorescence staining were used to confirm the establishment of CRC organoid models. Patient-derived xenograft (PDX) and nude mouse subcutaneous xenografts were used to evaluate the in vivo effect of targeting DSPP on oxaliplatin response. Results DSPP expression was significantly elevated in oxaliplatin-resistant patients and in oxaliplatin-resistant HCT8 cells. DSPP knockout significantly increased oxaliplatin sensitivity in oxaliplatin-resistant HCT8 cells and in HCT116 and SW620 cells. Co-immunoprecipitation revealed binding between DSPP and integrin αvβ3 in tumor cells, and immunofluorescence staining demonstrated their co-localization. Immunohistochemistry showed a positive correlation between DSPP expression and integrin αvβ3 expression in CRC tissues. Western blotting indicated that DSPP upregulated the phosphorylation levels of ERK and P53 in the MAPK signaling pathway, whereas the integrin αvβ3-targeted inhibitor (Cyclo) effectively abrogated this regulatory effect. In the xenograft and PDX models, targeted inhibition of DSPP or integrin αvβ3 suppressed tumor growth and improved the efficacy of oxaliplatin, for which the anti-DSPP monoclonal antibody was more effective than integrin αvβ3-targeted inhibitor. Conclusion We identified a DSPP-integrin αvβ3 axis that mediates oxaliplatin resistance, and DSPP may serve as a therapeutic target to restore chemosensitivity in advanced CRC.

Key words: colorectal cancer, chemotherapy resistance, dentin sialophosphoprotein, integrin αvβ3

Chaoqun LIU, Ziyan NING, Jianghua WU, Weiwei LIU, Chuang LIN, Jiawei XU, Rui ZHOU, Liang ZHAO. Tumor-secreted dentin sialophosphoprotein induces oxaliplatin resistance in colorectal cancer through an integrin αvβ3-dependent pathway[J]. Journal of Southern Medical University, 2026, 46(3): 479-488.

Figures/Tables 6

Fig.1 DSPP correlates with oxaliplatin responsiveness in colorectal cancer (CRC). A: Immunohistochemical (IHC) images showing DSPP expression in tumors from oxaliplatin (L-OHP)‑sensitive and ‑resistant CRC patients (***P<0.001). B: Quantification of DSPP IHC scores in L-OHP-sensitive and -resistant CRC tumors (n=30). C: CCK-8 assay for assessing viability of L-OHP-resistant HCT8 cell line (n=4). D: Western blotting of DSPP in L-OHP-sensitive HCT8 and L-OHP-resistant HCT8 cells. E: Western blotting confirming stable DSPP knockout in HCT8 cells. F: CCK-8 assay showing increased L-OHP sensitivity in DSPP-knockout HCT8 cells (n=4).

Tab.1 Baseline characteristics of oxaliplatin-sensitive and oxaliplatin-resistant colorectal cancer (CRC) samples

Characteristic	Level	Oxaliplatin-sensitive group (n=30)	Oxaliplatin-resistant group (n=30)	P
Gender	Male	20 (66.7%)	22 (73.3%)	0.778
	Female	10 (33.3%)	8 (26.7%)
Age (year)	≤50	9 (30.0%)	8 (26.7%)	0.974
	>50	21 (70.0%)	22 (73.3%)
T stage	T2	11 (36.7%)	0 (0.0%)	<0.001
	T3	16 (53.3%)	15 (50.0%)
	T4	3 (10.0%)	15 (50.0%)
N stage	N0	20 (66.7%)	13 (43.3%)	0.188
	N1	8 (26.7%)	13 (43.3%)
	N2	2 (6.7%)	4 (13.3%)
DSPP expression	High	13 (43.3%)	26 (86.7%)	0.001
	Low	17 (56.7%)	4 (13.3%)

Fig.2 DSPP depletion enhances oxaliplatin resistance in human CRC organoids and cell lines. A: Representative schematic of the establishment and characterization of patient-derived tumor organoids (PDTOs). Scale bar=100 μm. B: HE and immunofluorescence staining showing DSPP expression in edited PDTOs. Scale bar=100 μm. C: CCK-8 assay showing significantly increased L-OHP sensitivity in DSPP-knockout PDTOs (n=4). D: Western blotting showing the efficiency of DSPP knockout in HCT116 and SW620 cells. E: CCK-8 assays showing increased L-OHP sensitivity in DSPP knockout HCT116 and SW620 cells (n=4).

Fig.3 Targeting DSPP augments oxaliplatin efficacy in xenograft and PDX models.A: Representative subcutaneous xenograft tumors and IHC demonstrating the efficacy of combining L-OHP with a DSPP-targeting therapy (n=5). Scale bar=50 μm. B: Endpoint tumor weights in each group (n=5). C: Tumor growth curves over time in each group (n=5). D: Schematic diagram of patient-derived xenograft (PDX) establishment and treatment regimens. E, G, I: Representative macroscopic tumors, HE staining, and DSPP IHC from 3 independent PDX cases (n=5 or 6). Scale bar=200 μm. F, H, J: Tumor growth curves and tumor weights in the corresponding PDX cases. *P<0.05, **P<0.01, ***P<0.001.

Fig.4 DSPP interacts with integrin αvβ3 and modulates MAPK signaling. A, B: Co-immunoprecipitation (Co-IP) and immunofluorescence images showing the interaction and subcellular co-localization of DSPP and integrin αvβ3 in CRC cells. Scale bar=10 μm. C: Immunofluorescence images showing co-localization of DSPP and αvβ3 in CRC tissues. Scale bar=50 μm. D: IHC showing the correlation between DSPP and integrin αvβ3 expression in human CRC specimens. Scale bar=50 μm. E, F: Western blotting showing that DSPP regulates MAPK/ERK and p53 pathways in the indicated CRC cell lines, and the integrin-targeted inhibitor Cyclo (at a concentration of 38.33 ng/mL) reverses DSPP-induced upregulation of ERK and P53 phosphorylation levels.

Fig.5 Targeting DSPP or integrin αvβ3 enhances oxaliplatin efficacy in CRC PDX models. A: Schematic diagram of the PDX experimental design for evaluating L-OHP combined with DSPP-targeting antibody or αvβ3 inhibitor Cyclo(-RGDfK). B, E: Representative macroscopic tumors, HE staining, and DSPP IHC from two independent PDX cases (n=4-6). Scale bar=100 μm. C, F: Tumor growth curves for the indicated treatment groups (n=4-6). D, G: Endpoint tumor weights in each group (n=4-6). H: Body-weight monitoring of PDX mice across different treatment groups, showing no significant toxicity (n=4-6). I: HE staining of major organs (intestine, liver, heart, and spleen) from PDX mice across the treatment groups. Scale bar=50 μm. *P<0.05, **P<0.01, ***P<0.001.

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