CD45+ and CD45- cells of benign v/s metastatic mouse breast tumors

Metastasis remains a leading cause of all cancer related mortalities and therapeutic challenges. To successfully establish tumors and metastasiz, cancer cells must escape recognition and elimination by modulating immune cells during surveillance. Therapies that mount anti-tumor response of the adaptive immune system and target the immune evasion mechanisms have entered the clinic. However, the number of patients that respond to these therapies remains humble. This is likely due to the pro-tumor and immunosuppressive mechanisms of innate immune system that remain elusive. Tumor immune cells demonstrate tremendous intra- and inter-tumoral heterogeneity. Presence of high neutrophil to lymphocyte ratio is typically associated with high risk of metastasis and poor patient outcome, which suggests that immune cells, specifically myeloid cells of metastatic tumors have distinct biological functions. We aim to identify these distinct biological functions and the candidates that may have prognostic and therapeutic potential using a non-metastatic and metastatic tumor from the 4T1 mouse breast cancer model. 67NR (non-metastatic) and 66cl4 (metastatic) tumors of the immunocpmpetent 4T1 mouse breast cancer model were indiced in mice by orthotopic injections. After development of tumors, they were resected and dissociated to form single cell suspension. The cells were sorted based on CD45 expression into immune (CD45+) and non-immune (CD45-) cells. RNA was extracted from the sorted cell populations and transcriptome sequencing of immune and non-immune cells from both the tumors was done to understand the distinct biological functions associated with each subset. contributor: Genomic Core Facility

转移仍是所有癌症相关死亡及治疗难题的首要诱因。癌细胞若要成功定植肿瘤并发生转移，必须在免疫监视（immune surveillance）过程中通过调控免疫细胞，逃避免疫系统的识别与清除。目前，旨在激活适应性免疫系统抗肿瘤应答、靶向肿瘤免疫逃逸机制的疗法已步入临床，但此类疗法的应答患者数量仍十分有限。这一现象可能源于先天免疫系统的促肿瘤与免疫抑制机制尚未被阐明。肿瘤免疫细胞展现出显著的瘤内及瘤间异质性。高中性粒细胞与淋巴细胞比值通常与高转移风险及不良患者预后相关，这提示转移性肿瘤中的免疫细胞（尤其是髓系细胞）具备独特的生物学功能。本研究拟利用4T1小鼠乳腺癌模型中的非转移性与转移性肿瘤，甄别这些独特的生物学功能及具备预后与治疗潜力的候选靶点。具体实验方案如下：通过原位注射（orthotopic injection）在免疫健全（immunocompetent）的4T1小鼠乳腺癌模型中构建67NR（非转移性）与66cl4（转移性）肿瘤。待肿瘤生长至合适体积后，将其切除并解离为单细胞悬液（single cell suspension），基于CD45表达将细胞分为免疫细胞（CD45+）与非免疫细胞（CD45-）。随后从分群细胞中提取RNA，并对两类肿瘤的免疫细胞与非免疫细胞开展转录组测序（transcriptome sequencing），以解析各细胞亚群相关的独特生物学功能。供稿单位：基因组核心设施（Genomic Core Facility）