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Cyclooxygenase‐2 (COX‐2) is frequently expressed in many types of cancers exerting a pleiotropic and multifaceted role in genesis or promotion of carcinogenesis and cancer cell resistance to chemo‐ and radiotherapy. COX‐2 is released by cancer‐associated fibroblasts (CAFs), macrophage type 2 (M2) cells, and cancer cells to the tumor microenvironment (TME). COX‐2 induces cancer stem cell (CSC)‐like activity, and promotes apoptotic resistance, proliferation, angiogenesis, inflammation, invasion, and metastasis of cancer cells. COX‐2 mediated hypoxia within the TME along with its positive interactions with YAP1 and antiapoptotic mediators are all in favor of cancer cell resistance to chemotherapeutic drugs. COX‐2 exerts most of the functions through its metabolite prostaglandin E2. In some and limited situations, COX‐2 may act as an antitumor enzyme. Multiple signals are contributed to the functions of COX‐2 on cancer cells or its regulation. Members of mitogen‐activated protein kinase (MAPK) family, epidermal growth factor receptor (EGFR), and nuclear factor‐κβ are main upstream modulators for COX‐2 in cancer cells. COX‐2 also has interactions with a number of hormones within the body. Inhibition of COX‐2 provides a high possibility to exert therapeutic outcomes in cancer. Administration of COX‐2 inhibitors in a preoperative setting could reduce the risk of metastasis in cancer patients. COX‐2 inhibition also sensitizes cancer cells to treatments like radio‐ and chemotherapy. Chemotherapeutic agents adversely induce COX‐2 activity. Therefore, choosing an appropriate chemotherapy drugs along with adjustment of the type and does for COX‐2 inhibitors based on the type of cancer would be an effective adjuvant strategy for targeting cancer. Cyclooxygenase‐2 (COX‐2) is frequently expressed in many types of cancers exerting a pleiotropic and multifaceted role in genesis or promotion of carcinogenesis and cancer cell resistance to chemo‐ and radiotherapy. COX‐2 is released by cancer‐associated fibroblasts (CAFs), macrophage type 2 (M2) cells, and cancer cells to the tumor microenvironment (TME). COX‐2 induces cancer stem cell (CSC)‐like activity and promotes apoptotic resistance, proliferation, angiogenesis, inflammation, invasion, and metastasis of cancer cells. [ABSTRACT FROM AUTHOR]

Colorectal cancer (CRC) is the third most prevalent cancer in the world. There are many risk factors involved in CRC. According to recent findings, the tumor microenvironment and feces samples of patients with CRC are enriched by Fusobacterium nucleatum. Thus, F. nucleatum is proposed as one of the risk factors in the initiation and progression of CRC. The most important mechanisms of Fusobacterium nucleatum involved in CRC carcinogenesis are immune modulation (such as increasing myeloid‐derived suppressor cells and inhibitory receptors of natural killer cells), virulence factors (such as FadA and Fap2), microRNAs (such as miR‐21), and bacteria metabolism. The aim of this review was to evaluate the mechanisms underlying the action of F. nucleatum in CRC. One of the probabilities in colorectal cancer (CRC) development is Fusobacterium. F. nucleatum could contribute in CRC development through virulence factors, microRNAs (miRNA), immune evasion, and increasing metastasis. [ABSTRACT FROM AUTHOR]