Rho-ROCK signaling regulates tumor-microenvironment interactions.

Reciprocal biochemical and biophysical interactions between tumor cells, stromal cells and the extracellular matrix (ECM) result in a unique tumor microenvironment that determines disease outcome. The cellular component of the tumor microenvironment contributes to tumor growth by providing nutrients, assisting in the infiltration of immune cells and regulating the production and remodeling of the ECM. The ECM is a noncellular component of the tumor microenvironment and provides both physical and biochemical support to the tumor cells. Rho-ROCK signaling is a key regulator of actomyosin contractility and regulates cell shape, cytoskeletal arrangement and thereby cellular functions such as cell proliferation, differentiation, motility and adhesion. Rho-ROCK signaling has been shown to promote cancer cell growth, migration and invasion. However, it is becoming clear that this pathway also regulates key tumor-promoting properties of the cellular and noncellular components of the tumor microenvironment. There is accumulating evidence that Rho-ROCK signaling enhances ECM stiffness, modifies ECM composition, increases the motility of tumor-associated fibroblasts and lymphocytes and promotes trans-endothelial migration of tumor-associated lymphocytes. In this review, we briefly discuss the current state of knowledge on the role of Rho-ROCK signaling in regulating the tumor microenvironment and the implications of this knowledge for therapy, potentially via the development of selective inhibitors of the components of this pathway to permit the tuning of signaling flux, including one example with demonstrated utility in pre-clinical models.

Macrophages infiltrating endometriosis-like lesions exhibit progressive phenotype changes in a heterologous mouse model.

Endometriotic lesion development involves complex interactions between endometrial tissue, the peritoneum and immune cells. Macrophages are essential in this process; however their precise roles are not defined. To investigate whether infiltrating macrophages acquire functionally different phenotypes during lesion development, human endometrial tissues were grafted into immunodeficient mice expressing macrophage-specific green fluorescent protein (GFP). Although the numbers of GFP-positive macrophages were similar in lesions 4, 7, 10 and 14 days after grafting, their surface markers changed over time. Inflammatory markers MHC class II (MHC II) and iNOS were present on 36% and 41% of macrophages respectively early in lesion development at day 4, whereas abundance of tissue remodelling markers peaked later, with arginase 1 most highly expressed on 57% of macrophages at day 7 and scavenger receptor A (CD204) on 66% of macrophages at day 14. This is consistent with a transition from classical M1 macrophage activity to an alternate M2 profile, which correlates to histological hallmarks of initially acute inflammation followed by tissue remodelling during lesion development. This progressive shift in phenotype is likely to be relevant to the mechanisms by which macrophages are central players in endometriosis-like lesion development.