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Using transgenic mouse models of breast cancer that ablate Src homology and collagen A (ShcA) expression or oncogene-coupled ShcA signaling, we previously showed that this adaptor is critical for mammary tumor onset and progression. We now provide the first evidence that ShcA regulates mammary tumorigenesis, in part, through its ability to regulate the adaptive immune response. Inactivation of ShcA signaling within tumor cells results in extensive CD4+ T-cell infiltration and induction of a humoral immune response in mammary tumors. This is associated with a robust CTL response in preneoplastic lesions that are deficient in ShcA signaling. Moreover, mammary tumor progression of ShcA-deficient hyperplasias is accelerated in a T cell–deficient background. We also uncover a clinically relevant correlation between high ShcA expression and low CTL infiltration in human breast cancers. Finally, we define a novel ShcA-regulated immune signature that functions as an independent prognostic marker of survival in human epidermal growth factor receptor 2+ and basal breast cancers. We reveal a novel role for tumor cell–derived ShcA in the establishment and maintenance of an immunosuppressive state. Cancer Res; 70(20); 7776–87. ©2010 AACR.

A recent convergence of clinical and epidemiological evidence suggests that hyperinsulinemia associated with obesity and type 2 diabetes leads to higher incidence and poor outcome of breast cancer (BC). To probe the role of insulin signaling in BC, we created the MMTV-driven polyoma middle T BC model mice with an inducible mammary epithelium-specific deletion of the insulin receptor (INSR). Deletion of INSR in the mammary gland considerably reduced the mammary tumour burden in the INSR knockout mice as compared to the INSR wildtype controls, without affecting the tumour onset. The average weight of individual tumours was similar across the genotypes, suggesting that deletion of INSR affected the tumour initiation potential of the epithelial cells rather than tumour growth. Deletion of INSR also affected the metastasis of mammary tumours to the lung, with the INSR knockout mice presenting with half the number of metastases compared to the INSR wildtype controls. Our ongoing efforts are focused on mapping the signaling events downstream of the INSR that govern tumour initiation and metastasis in our mice, as well as modeling the impact of obesity on tumors in this model system, with the ultimate goal of identifying the role of INSR signaling in BC development and progression. Citation Format: Yekaterina Poloz, Samar Mouaaz, Sonya Lam, Vuk Stambolic. Insulin receptor signaling contributes to mammary tumorigenesis in mice. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 664.