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• Mast cells (MCs), a type of innate immune cells, come from myeloid stem cells. MCs show different roles in cancer. • MCs have pro-tumorigenic or anti-tumorigenic role depending on the type of cancer, the degree of tumor progression, and the location of these immune cells in the tumor bulk. • Regulation of MC activation, recruitment, and type of released mediators at the tumor site can be useful for management and control of tumor growth. Please find the new points, You can replace these points with the previous version. Mast cells (MCs), a type of innate immune cells, are derived from myeloid stem cells, sometimes known as mastocytes or labrocytes, and contain many granules rich in histamine and heparin. The mentioned cells are able to release various mediators such as cytokines, leukotrienes, and a large number of proteases into the environment. Many studies and experiments have established the infiltration of MCs into the tumor site. However, the findings are highly controversial to determine whether these immune cells contribute to the growth and development of the tumor or cause anti-tumor immune responses. Various studies have revealed that MCs have a pro-tumorigenic or anti-tumorigenic role depending on the type of cancer, the degree of tumor progression, and the location of these immune cells in the tumor bulk. Although these types of immune cells cause angiogenesis and tumor progression in some cancers, they have a significant anti-tumor role in some other types of cancers. In general, although a number of studies have specified the protective role of MCs in cancers, the increased number of MCs in the blood and microenvironment of tumors, as well as the increased level of angiogenesis and tumor progression, has been indicated in another array of studies. The function of MCs against or in favor of the cancers still requires further investigations to more accurately and specifically determine the role of MCs in the cancers. The function of MCs in tumors and their various roles in case of exposure to the cancer cells have been addressed in the present review. The concluding section of the present study recommends a number of methods for modification of MCs in cancer immunotherapy. [ABSTRACT FROM AUTHOR]

Highlights • Cancer stem cells (CSCs) have the ability to self-regenerate and recurrent the tumor. • The immune system can somehow fight with CSCs, but will eventually become weakened by these cancerous cells. • The immune cells are altered when they come into contact with CSCs, and somewhat obedient to the tumor. Abstract Cancer stem cells (CSCs) are a subgroup of tumor cells that are characterized by their tumor initiating capacity, low proliferation rate, self-renewal capacity, pluripotency and chemoresistance. The immune system, including innate and adaptive immune cells, plays pro-tumorigenic and anti-tumorigenic roles in cancer biology. Immunosurveillance often initially successfully eradicates tumor cells. However, following a phenomenon referred to as immunoediting, cancer cells may ultimately evade immune destruction, thus enabling tumor progression. Here, we review how CSCs both escape immune destruction and foster establishment of an immunosuppressive tumor microenvironment through intricate interactions with and recruitment of a broad range of immune cells, including natural killer (NK) cells, myeloid-derived suppressor cells (MDSCs), regulatory T cells (Tregs), tumor-associated macrophages (TAMs), cytotoxic T-lymphocytes (CTLs) and T helper (Th) cells. Further elucidation of CSC-immune cell interactions and the underlying signaling mechanisms will open up novel opportunities to improve cancer immunotherapy. [ABSTRACT FROM AUTHOR]