The Role of Stroma in Ovarian Cancer

Background: Ovarian cancer is one of the gynecological malignancies responsible for thousands of deaths in women worldwide. Malignant solid tumors are formed by malignant cells and stroma that influence each other, where different types of cells in the stromal environment can be recruited by malignant cells to promote tumor growth and facilitate metastasis. The chronic inflammatory response is increasingly accepted in its relation to the pathophysiology of the onset and development of tumors, sustained cell proliferation in an environment rich in inflammatory cells, growth factors, activated stroma and DNA damage agents may increase the risk to develop a neoplasm.Methods: A search for the following keywords was performed in the PubMed database; "Ovarian cancer", "stroma", "tumor-associated macrophages", "cancer-associated fibroblasts", "cytokines", "angiogenesis", "epithelial-mesenchymal transition", and "extracellular matrix".Results: The articles identified were published in English between 1971 and 2018. A total of 154 articles were selected for further analysis. Conclusion: We consider ovarian cancer as a heterogeneous disease, not only in the sense that different histological or molecular subtypes may be behind the same clinical result, but also that multiple cell types besides cancer cells, like other non-cellular components, need to be mobilized and coordinated to support tumor survival, growth, invasion and progression.

[Breast cancer, obesity and adipose tissue: a high-risk combination]

Obesity increases the occurrence of post-menopausal breast cancer and negatively affects prognosis independently of menopausal status. After summarizing the available epidemiological data concerning these associations, we will show that a deleterious crosstalk is established during tumor progression between cancer cells and the surrounding mammary adipose tissue (MAT). In obesity, the chronic sub-inflammatory state of MAT could amplify the negative effect of this crosstalk although other mechanisms also warrant further study. Finally, we will discuss the efficiency of weight loss in both primary prevention and recurrence, a strategy that could be more complex that initially thought.

[The tumoral microenvironment: feeding resources, battle field and therapeutic target in cancer]

Tumors grow surrounded by a complex cellular and tissular microenvironment. Its components influence disease outcome, some accelarating growth and invasion and others blocking it. From the very first steps leading a normal tissue to dysplasia, followed by a benign tumor which may become locally invasive and metastatic, interactions between the transformed cells and their microenvironment direct the evolution of this process. Chronic inflammation in a tissue favors tumor first appearance which then accentuate the nutritional and energetic properties of their microenvironment by producing neoangiogenic, immunosuppressive and inflammatory molecules. In contrast a strong memory Th1/cytotoxic reaction can prevent the transition from benign to malignant tumors and control cancer invasivness and metastasis. Knowledge of these multiple phenomena, discussed in the different articles of the present issue has a major clinical impact, since new prognostic tests and efficient novel therapeutic approaches which target the tumor microenvironment are actively developed.

[Carcinoma-associated fibroblasts in cancer: the great escape]

Cellular and molecular crosstalks between cancer and non-cancer tumor-associated cells result in tumor growth and metastatic spreading. During carcinoma development, tumor cells secrete signaling molecules that influence the surrounding non-cancer cells, which, in return, favor tumor cell growth, survival, migration and metastasis. Carcinoma-associated fibroblasts (CAF) are the most abundant population of non-cancer cells found in tumors, and their presence is often associated with poor clinical prognosis. Here, we summarize the pro-carcinogenic roles of CAF cells during carcinogenesis, with a specific focus on their abilities to drive cancer cell-dependent pro-invasive extracellular matrix remodeling.