CD8 + T-cells restrict the development of peritoneal metastasis and support the efficacy of hyperthermic intraperitoneal chemotherapy (HIPEC).

Multimodal therapy for peritoneal metastasis (PM) including cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) provides long-term survival in highly selected colorectal cancer patients. Mechanisms behind HIPEC are unknown and may include induction of adaptive immunity. We therefore analyzed human PM samples and explored the impact of HIPEC in experimental models. Human samples from colorectal primary tumors (n = 19) and PM lesions (n = 37) were examined for the presence of CD8 + T-cells and their association with disease free (DFS) and overall survival (OS). CD8 + T cell response after HIPEC was assessed using an in-vivo PM mouse model, tumor cell lines and patient-derived tumor organoids. Patients with high intraepithelial CD8 + T cell counts showed longer DFS and OS. In the mouse model, HIPEC controlled growth of PM and increased numbers of functional granzyme positive CD8 + T cells within tumors. Cell lines and human organoids that were treated with heated chemotherapies showed immunogenic changes, reflected by significantly higher levels of MHC-class I molecules and expression of Cancer Testis Antigens Cyclin A1 and SSX-4. Using in-vitro co-culture assays, we noticed that cancer cells treated with heated chemotherapy primed dendritic cells, which subsequently enhanced effector functions of CD8 + T cells. The presence of CD8 + T-cells within PM lesions is associated with prolonged survival of patients with PM. Data from PM mouse model and in-vitro assay show that heated chemotherapies induce immunogenic changes on cancer cells leading to induction of CD8 + T-cells mediated immunity, which seems to control growth of PM lesions in mice after HIPEC.

Deletion of Protein Tyrosine Phosphatase Nonreceptor Type 2 in Intestinal Epithelial Cells Results in Upregulation of the Related Phosphatase Protein Tyrosine Phosphatase Nonreceptor Type 23.

BACKGROUND/AIMS: Knockdown of protein tyrosine phosphatase nonreceptor type 2 (PTPN2) exaggerates IFN-γ-induced intestinal barrier defects, but mice constitutively lacking PTPN2 in epithelial cells (PTPN2xVilCre mice) do not show changes in epithelial function or enhanced susceptibility to experimental colitis. Here, we investigated whether PTPN2 modulates the expression of related tyrosine phosphatases. METHODS: PTPN2 knockdown in HT-29 cells was induced using siRNA constructs. Acute colitis in PTPN2xVilCre mice was induced by 2% dextran sulfate sodium (DSS) in drinking water for 7 days. Colitis-associated tumors were induced by injection of azoxymethane prior to treatment with DSS for 3 consecutive cycles. RESULTS: In HT-29 cells, PTPN2 depletion resulted in enhanced mRNA expression of PTPN11 and PTPN23 and in parallel to upregulation of IL-18 mRNA upon treatment with TNF for 24 h. DSS treatment of PTPN2-deficient mice resulted in a strong induction of Ptpn23 mRNA in colon tissue in vivo. In the tumor model, Ptpn23 mRNA was again clearly upregulated in nontumor tissue from PTPN2-deficient mice; however, this was not observed in tumor tissue. CONCLUSIONS: Our experiments show that PTPN23 function might, at least partially, compensate lack of PTPN2 in epithelial cells. Upregulation of PTPN23 might therefore crucially contribute to the lack of a colitis phenotype in PTPN2-VilCre mice.