Efficacy of zinc carnosine in the treatment of colorectal cancer and its potential in combination with immunotherapy

Abstract

Zinc-L-carnosine (ZnC), a combination of zinc and carnosine that has been widely used to treat peptic ulcers and as a therapeutic component of zinc supplements. Recently, it has also been observed that ZnC has potential effects on cancer treatment. Uncertainty persists about the biological roles played by ZnC as well as the tumor immune microenvironment (TIME) in colorectal cancer (CRC). This study aims to evaluate how ZnC influences CRC advancement through proliferation, invasion, migration, and immunological impact. The cell counting kit 8 (CCK8), 5-ethynyl-2'- deoxyuridine (EdU), transwell, and wound healing assays served for investigating the effect of ZnC on the proliferation, migration and invasion regarding CRC cell lines (HCT116, LOVO) in vitro. Quantitative real time polymerase chain reaction (qRTPCR) was performed to compare the changes in miR-570 and programmed cell death- Ligand 1(PD-L1) mRNA expression after ZnC or phosphate belanced solution (PBS) is added in CRC cells. Western blotting was performed to compare the changes in PDL1 protein expression. C57BL/6 mice’ CRC subcutaneous tumor samples were selected for evaluating the anticancer effectiveness of ZnC and relevant impact on the TIME. After receiving ZnC therapy, the immunological microenvironment of the CRC tumor was verified by mass cytometry. According to abovementioned assays, ZnC prevented CRC cell lines from proliferating, invading, and migrating. ZnC may increase PD-L1 expression by blocking miR-570. In vivo research shown that ZnC gavage prevented the development of CRC tumors and pairing with anti-PD1 therapy greatly increased anti-programmed cell death 1(PD1) therapy's efficacy in the treatment of CRC. Mass cytometry results showed that immunosuppressive cells including regulatory T cells (Tregs), bone marrow-derived suppressor cells (MDSC), and M2 macrophages decreased whereas CD8+ T cells increased after ZnC addition. CD8+ CCR6 decreased whereas CD8+ ICOS expression increased in ZnC group compared with PBS group. The present study reveals that ZnC slows the progression of CRC by inhibiting the proliferation, invasion and migration of CRC cells and upregulates PD-L1 expression via inhibiting miR-570. The combination of ZnC and anti-PD1 therapy is beneficial to synergically increase efficacy of anti-tumor in CRC therapy.