(P23-001-23) Role of CXCL7 in Colon Cancer Progression

Objectives: Chemokine (C-X-C motif) ligand 7 (CXCL7) is a potential biomarker for the colorectal cancer (CRC) diagnosis. However, its role in CRC progression is not known. Hence, we examined the role of CXCL7 in mediating colon cancer proliferation through enhanced aerobic glycolysis

Methods: Using colon cancer cells (HT-29) transfected with CXCL7 or an empty vector as a control, we examined the effect of CXCL7 on cellular proliferation and glycolytic flux. HT-29 cells were transfected with a human CXCL7/pro platelet basic protein (PPBP) plasmid, and stable CXCL7 expressing cells were selected using Hygromycin. Transfection efficiency was confirmed by analyzing PPBP
expression by RT-qPCR and measuring secreted CXCL7 in culture media by ELISA. Cancer cell proliferation was assessed by measuring EdU incorporation in DNA. We monitored the glycolytic flux by assessing glucose uptake using a fluorescent derivative of 2-deoxyglucose (2-NBDG) and determining lactate accumulation in the cultured cell’s media. In addition, we treated HT-29 cells with conditioned media (CM) from HEK-293T transfected CXCL7 cells or vector transfected cells as a control. The specificity of CXCL7 actions were examined using a CXCL7 neutralizing antibody and an antagonist (SB225002) to the CXCL7 receptor, CXCR2.

Results: We observed a 10-fold increase in the CXCL7 mRNA and a 52-fold increase in the secreted CXCL7 protein in CXCL7-expressing HT-29 cells. The proliferation rate in CXCL7 expressing HT-29 cells and HT-29 cells cultured with the CXCL7-CM were significantly higher (1.2-fold and 1.8-fold, respectively) compared to controls (p < 0.01). Importantly, blocking the CXCL7/CXCR2 axis using the CXCL7 neutralizing antibody and CXCR2 inhibitor abrogated CXCL7-stimulated proliferation. Lactate levels were two-fold higher in both culture media of CXCL7-expressing HT-29 cells and HT-29 cells treated with CXCL7-CM compared to the controls (p < 0.05). Glucose uptake was also greater in CXCL7 overexpressing cells and CXCL7-CM treated cells compared to vector controls.

Conclusions: Our study for the first time showed that CXCL7 stimulates cell proliferation and lactate production in HT-29 colon cancer cells, suggesting that CXCL7 may stimulate colon cancer proliferation by modulating aerobic glycolysis.

Funding Sources: NIFA award (ALA044-1-18037)