Role of Tumor Specific niche in Colon Cancer Progression and Emerging Therapies by Targeting Tumor Microenvironment.

Colorectal cancer is the third most common form of cancer worldwide leading to escalating mortality rates and mainly includes hereditary, sporadic and colitis-associated cancer development. The escalated mortality rates is due to the limited treatment options as this form of cancer is usually not easy to diagnose in its early stages and are highly invasive leading to rapid metastasis of the malignant cells to the neighbouring tissue. In order to combat this limitation several chemotherapeutic regimens are now being combined with targeted therapies after the knowledge acquired on the inevitable effects of the tumor microenvironment on the colon cancer growth and progress. The colon tumor niche mainly consists of a large mass of tumor cells along with various immune cells, inflammatory cells, tumor macrophages and fibroblasts that infiltrate the tumor as it is a site of predominant inflammation. Among cells of the microenvironment, mesenchymal stem cells (MSCs) exhibiting ability to evolve into cancer associated fibroblasts (CAFs) have recently generated a major interest in the field. The physiological state of the tumor microenvironment is closely connected to discrete steps of tumorigenesis. The colon cancer cells elicit various factors with their direct interaction with MSCs or via paracrine fashion, which modulate these cells to promote cancer instead of performing their innate function of abating cancer progression. This review intends to highlight the necessity to exploit the cellular landscape of tumor microenvironment of colon cancer and a detailed understanding of the interactions between tumor epithelial cells and their stromal/inflammatory elements will aid in future perspectives for designing therapeutic regimens targeting tumor microenvironment to improve the clinical outcome of colon cancer.