Tumor-associated macrophages (TAMs) constitute the main population of immune cells present in the ovarian tumor microenvironment. These cells are characterized by high plasticity and can be easily polarized by colony-stimulating factor-1, which is released by tumor cells, into an immunosuppressive M2-like phenotype. These cells are strongly implicated in both the progression and chemoresistance of ovarian cancer. The main pro-tumoral function of M2-like TAMs is the secretion of a variety of cytokines, chemokines, enzymes and exosomes that reach microRNAs, directly inducing the invasion potential and chemoresistance of ovarian cancer cells by triggering their pro-survival signaling pathways. The M2-like TAMs are also important players in the metastasis of ovarian cancer cells in the peritoneum through their assistance in spheroid formation and attachment of cancer cells to the metastatic area—the omentum. Moreover, TAMs interplay with other immune cells, such as lymphocytes, natural killer cells, and dendritic cells, to inhibit their responsiveness, resulting in the development of immunosuppression. The detrimental character of the M2-like type of TAMs in ovarian tumors has been confirmed by a number of studies, demonstrating the positive correlation between their high level in tumors and low overall survival of patients.

Interleukin 6 (IL-6) is a pleiotropic cytokine that is strongly implicated in the development and progression of ovarian cancer. The most recognized actions of IL-6 in ovarian cancer (OC) cells are the induction of cell proliferation and inhibition of cell apoptosis. Equally important is its ability to enhance the migratory and invasive potential of OC cells. Moreover, the increased expression and secretion of this cytokine positively correlates with OC cell chemoresistance. Elevated concentrations of IL-6 are observed in the serum and ascites of ovarian cancer patients. Thus, its level is discussed in the literature as a potential biomarker that can help to discriminate malignant and nonmalignant ovarian tumors and allow for the prediction of the chemotherapy response. The importance of IL-6 in ovarian cancer is proved by the fact that this cytokine is a potential target to anti-cancer therapy. This review is divided into two parts. The first summarizes the general biological activity of IL-6, and overviews its impact on OC cells, as well as discusses the current proposition of IL-6 inclusion in combination of anti-OC therapy. The second part is a systematic review of IL-6 as a possible biomarker in ovarian cancer patients.

The aim of the present retrospective study was to compare microRNA (miR)-146a expression levels in primary tumors and omental metastases of 48 patients, who had undergone surgery for advanced ovarian serous cancer. Possible correlations between miR-146a expression level and clinicopathological features were investigated, including chemosensitivity and survival. miR-146a was evaluated in formalin-fixed, paraffin-embedded samples. miR-146a expression level in primary tumors was demonstrated to be increased in comparison with normal ovary tissues (P=0.02) and metastases (P=0.01). A negative correlation was demonstrated between miR-146a expression in primary tumors and serum levels of cancer antigen 125 (R=−0.37; P=0.03) and Risk of Malignancy Algorithm index (R=−0.79; P=0.0007). Overall survival positively correlated with miR-146a expression in primary tumor tissue samples (R=0.38; P=0.01). Probability of survival was decreased in patients with low miR-146a expression levels in primary tumor tissues (hazard ratio=0.21; P=0.003). Lower levels of miR-146a in primary tumor tissue samples were correlated with a shorter progression-free survival (P=0.04) and platinum-resistance of metastases (P=0.006). In conclusion, miR-146a may be a prognostic marker for serous ovarian cancer.