VSIG4 Is Dispensable for Tumor Growth and Metastasis in Murine Colorectal and Breast Cancer Models.

Background: Tumor-associated macrophages (TAMs) are important contributors to tumor progression and metastasis. Therefore, the identification of molecules that mediate these cells' tumor-promoting functions is highly warranted. VSIG4 has been proposed as a macrophage immune checkpoint. Hence, we aim to investigate this marker in preclinical models.

Methods: Publicly available scRNAseq datasets of human colorectal (CRC) and triple-negative breast (TNBC) carcinomas and their murine counterparts were reanalyzed to investigate the expression of VSIG4 in the different TAM populations. Moreover, tumors were grown in Vsig4-deficient mice to evaluate the effect on primary tumor characteristics. Finally, since liver Kupffer cells and large peritoneal macrophages are at least partly VSIG4-high, and are implicated in metastasis to those organs, the dissemination of CRC cancer cells to those sites was assessed in the Vsig4-deficient mice.

Results: We demonstrate that VSIG4 expression in human CRC and TNBC is mostly restricted to TAMs, and that its expression correlates with a worse prognosis. However, a striking finding was that no Vsig4 mRNA nor protein could be detected in the microenvironment of primary CRC and TNBC murine tumors, resulting in a similar tumor growth in wild type versus Vsig4-deficient mice. Moreover, no major differences were observed in metastatic tumor load in the liver and peritoneal cavity, apart from a reduced metastasis to the omentum in Vsig4-deficient animals.

Conclusions: Murine cancer models are not suitable to investigate the role of VSIG4 in primary tumors and VSIG4 deficiency did not alter liver nor peritoneal cavity metastasis in murine models, with the exception of the omentum.