#883 P-cresyl sulphate and Indoxyl sulphate: two uremic toxins stimulating colon cancer progression in patients with chronic renal failure

Abstract Background and Aims Chronic kidney disease (CKD) leads to the accumulation and production of uremic toxins, such as Indoxyl Sulphate (IS) and P-cresyl sulphate (p-CS). These toxins have been found to activate various processes that promote tumor growth. The literature has reported a two-fold increase in the incidence of colon cancer (CRC) and a worse prognosis in CKD patients, although the specific mechanisms underlying this association have not been fully elucidated. Given the pro-oncogenic activities of p-CS and IS at both the systemic and intestinal levels, it is plausible that these toxins contribute to the heightened aggressiveness of CRC in CKD patients. Method In order to assess the impact of toxins detected in uremic patients, we conducted experiments using three different colorectal cancer (CRC) cell lines (HT29, Hct116, LoVo). We tested various concentrations of IS and p-CS and measured their effects on tumor cell proliferation through a colorimetric assay called WST-8. For further analysis of cell survival, we performed a clonogenic assay. To investigate the migratory abilities of tumor cells after toxins treatment, we conducted a wound healing assay. Additionally, we assessed the invasive capacities of the three CRC cell lines post treatment with IS and p-CS using an invasion assay. In order to identify the specific pathways affected by toxins exposure, we conducted Real Time PCR and Western blot analysis to evaluate the inflammatory pathway and the epithelial-mesenchymal transition (EMT), respectively. Results The results of this study are remarkable, as we observed a notable increase in cell growth after exposure of cultured cells to various concentrations of toxins, as compared to the control group. Furthermore, the concentrations of IS and p-CS induced a substantial enhancement in cell migration and invasion. In the case of HCT116 cells treated with uremic toxins, there was an up-regulation of Vimentin protein expression, while E-cadherin expression was down-regulated compared to the control group. These proteins are crucial in the process of Epithelial-Mesenchymal Transition (EMT). Additionally, we evaluated the expression of genes associated with the inflammatory process (TNF-alpha, INOS, and IL-6) in the HT-29 and LoVo cell lines. Interestingly, we observed an up-regulation of these genes. Of particular importance, in the LoVo cell line, IL-6 exhibited the most significant increase in expression. Conclusion Based on these preliminary results, it appears that IS and p-CS play a key role in the progression of CRC in patients with CKD.