Abstract 2172: Dying tumor cells (tumor debris) stimulate the growth of 4T1 breast cancer tumor in female athymic nude mice

Abstract Current cancer therapies are based on chemotherapy and radiation. These therapeutic approaches can initially reduce the tumor mass or tumor burden by killing tumor cells. It has been postulated that the resulting dying tumor cells, or tumor debris, can act as sources of tumor stimulation on surviving cells leading to reappearance of the cancer, and thereby drastically reducing the survival rate. In our study we investigated whether 4T1 debris induced by chemotherapeutic agent docetaxel would affect breast tumor growth in female nude mice. Female athymic nude mice were divided into three groups: Group 1 was inoculated with 4T1 cells; Group 2 with 4T1 cells together with their debris and Group 3 with debris alone. All mice were fed a regular diet. After four weeks, the mice were sacrificed; tumors were excised, weighed and processed for histology and immunohistochemistry for inflammation parameters. Tumor weight significantly increased in Group 2 mice compared to the control Group 1. Group 3 mice developed no tumors. Although the tumor histology for both Groups 1 and 2 were similar, there were significant differences in inflammatory parameters in the two groups. Tumors developed in Group 2 mice had intense staining patterns for TNF-alpha, IL-6, Ki-67, i-Nos and VEGF compared to tumors in the control Group 1. Our results show that dying cells from docetaxel treatment, or tumor debris, had stimulatory effect on growth of breast cancer 4T1 cells in nude mice which was associated with increased inflammation. This study represents a novel method to evaluate the effects of chemotherapy or radiation on surviving tumor cells and to investigate the effect of various inhibitors on the growth recurrence. Citation Format: M Waheed Roomi, Aleksandra Niedzwiecki, Matthias Rath. Dying tumor cells (tumor debris) stimulate the growth of 4T1 breast cancer tumor in female athymic nude mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2172.