TNF-α sensitizes chemotherapy and radiotherapy against breast cancer cells

Preclinical and clinical aspects of TNF-α and its receptors TNFR1 and TNFR2 in breast cancer

Breast cancer is the most common malignancy in women and a public health problem worldwide. Breast cancer is often accompanied by an inflammatory process characterized by the presence of proinflammatory cytokines such as tumor necrosis factor (TNF-α), which has important implications in the course of the disease. Inflammation has been described primarily as a favorable environment for tumor development. However, under certain conditions TNF-α can promote signals for activation, differentiation, survival or cell death, so the study of the variants of this cytokine, its receptors, the presence of polymorphisms and its implication in different phenotypes of breast cancer is necessary. Although the clinical application of TNF-α has been limited by its toxicity and side effects, preclinical and clinical studies have shown that these effects may partially be avoided via tumor-targeted delivery strategies. In this manner, TNF-α alone or combined with chemotherapy and radiotherapy can function as an adjuvant in the treatment of breast cancer.

The Role of Tumor Microenvironment in Chemoresistance: To Survive, Keep Your Enemies Closer

Chemoresistance is a leading cause of morbidity and mortality in cancer and it continues to be a challenge in cancer treatment. Chemoresistance is influenced by genetic and epigenetic alterations which affect drug uptake, metabolism and export of drugs at the cellular levels. While most research has focused on tumor cell autonomous mechanisms of chemoresistance, the tumor microenvironment has emerged as a key player in the development of chemoresistance and in malignant progression, thereby influencing the development of novel therapies in clinical oncology. It is not surprising that the study of the tumor microenvironment is now considered to be as important as the study of tumor cells. Recent advances in technological and analytical methods, especially ‘omics’ technologies, has made it possible to identify specific targets in tumor cells and within the tumor microenvironment to eradicate cancer. Tumors need constant support from previously ‘unsupportive’ microenvironments. Novel therapeutic strategies that inhibit such microenvironmental support to tumor cells would reduce chemoresistance and tumor relapse. Such strategies can target stromal cells, proteins released by stromal cells and non-cellular components such as the extracellular matrix (ECM) within the tumor microenvironment. Novel in vitro tumor biology models that recapitulate the in vivo tumor microenvironment such as multicellular tumor spheroids, biomimetic scaffolds and tumor organoids are being developed and are increasing our understanding of cancer cell-microenvironment interactions. This review offers an analysis of recent developments on the role of the tumor microenvironment in the development of chemoresistance and the strategies to overcome microenvironment-mediated chemoresistance. We propose a systematic analysis of the relationship between tumor cells and their respective tumor microenvironments and our data show that, to survive, cancer cells interact closely with tumor microenvironment components such as mesenchymal stem cells and the extracellular matrix.

Genetic association between TNF-α promoter polymorphism and susceptibility to squamous cell carcinoma, basal cell carcinoma, and melanoma: A meta-analysis

Tumor necrosis factor-alpha (TNF-α) is a multifunctional pro-inflammatory cytokine that plays an important role in cancer development. We performed a meta-analysis to assess the relationship between single nucleotide polymorphisms in the TNF-α promoter region (rs1800629 and rs361525) and susceptibility to squamous cell carcinoma (SCC), basal cell carcinoma (BCC) and melanoma. After database retrieval, article selection, data extraction, and quality assessment, 20 articles comprising 4865 cases and 6329 controls were included in this study. rs1800629 was associated with an increased overall risk of SCC, lung SCC, and oral SCC in the AA vs G and AA vs GG+GA genetic models (all OR>1, P_association<0.05). No increased risk of skin SCC, skin BCC or melanoma was observed (all P_association>0.05). Rs361525 was not associated with overall SCC risk in the allele, heterozygote, dominant, recessive, or carrier model (all P_association>0.05). Begg's and Egger's tests (P_Begg>0.05; P_Egger>0.05) demonstrated there was no significant publication bias. These data indicate that the AA genotype of TNF-α rs1800629, but not rs361525, is associated with an increased risk of SCC, suggesting it could potentially serve as a prognostic marker for predicting SCC risk.