Abstract 1019: Salmonella break tumor immune tolerance by downregulation tumor indoleamine 2, 3-dioxygenase 1 expression

Abstract

Abstract Over past decades, bacteria have been proven the capability of inhibiting tumor growth. It can specifically target tumor and due to its facultative anaerobe property, can be more penetrative than other drug therapies. However, the molecular mechanism that bacteria inhibit tumor growth is still incompletely known. Here we used Salmonella choleraesuis to investigate the mechanism. The antitumor therapeutic effect mediated by Salmonella is associated with an inflammatory immune response at tumor site and T helper 1-type immune response. Many tumors have been proven high expression of indoleamine 2, 3-dioxygenase 1 (IDO), which is a rate-limiting enzyme that catalyzes tryptophan to kynurenine thus causing immunotolerance within tumor microenvironment. Our previous studies elucidated that Salmonella can also upregulate connexin 43 (CX43) to inhibit tumor progression and even enhance tumor chemosensitivity. Herein, we demonstrated that Salmonella can inhibit IDO expression through upregulation of CX43 in melanoma cells. Furthermore, we can also find the same phenomena in CX43 knock-down 4T1 and B16F10 cells. In brief, we point out that Salmonella-induced CX43 expression is a modulator of IDO expression and may play a crucial role in anti-tumor therapy, which combined with immunotherapy and Salmonella may be a prospective anti-tumor strategy. Citation Format: YU-DIAO KUAN, Che-Hsin Lee. Salmonella break tumor immune tolerance by downregulation tumor indoleamine 2, 3-dioxygenase 1 expression. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1019. doi:10.1158/1538-7445.AM2014-1019