Genetic alterations in human tumors

Immunology Behind Tumors: A Mini Review

Background::

The immune system is designed with great care to distinguish self from non-self, as exhibited by immune responses to different pathogens. Furthermore, the immune system has the capacity to distinguish between self from altered self in case of autoimmune diseases like cancer. Developing tumors bypass the immune system mechanism which restrains selfreactive responses. Immunotherapy is a coherent means since the immune system can eliminate a number of antigens derived from the genetic constitution of B and T lymphocytes. Our understanding of the immune system has developed a great deal.

Conclusion::

This review is focused not only on the mechanism by which the immune system protects us but also on the ways in which it can inflict the body and how to modulate it with therapy. Thus, understanding the interaction of a tumor with the immune system provides insights into mechanisms that can be utilized to elicit anti-tumor immune responses. Here, we have recapitulated the function of the tumor microenvironment and immune checkpoints.

CpG methylation as a mechanism for the regulation of E2F activity

Regulation of gene expression in mammals through methylation of cytosine residues at CpG dinucleotides is involved in the development and progression of tumors. Because many genes that are involved in the control of cell proliferation are regulated by members of the E2F family of transcription factors and because some E2F DNA-binding sites are methylated in vivo, we have investigated whether CpG methylation can regulate E2F functions. We show here that methylation of E2F elements derived from the dihydrofolate reductase, E2F1, and cdc2 promoters prevents the binding of all E2F family members tested (E2F1 through E2F5). In contrast, methylation of the E2F elements derived from the c-myc and c-myb promoters minimally affects the binding of E2F2, E2F3, E2F4, and E2F5 but significantly inhibits the binding of E2F1. Consistent with these studies, E2F3, but not E2F1, activates transcription through methylated E2F sites derived from the c-myb and c-myc genes whereas both E2F1 and E2F3 fail to transactivate a reporter gene that is under the control of a methylated dihydrofolate reductase E2F site. Together, these data illustrate a means through which E2F activity can be controlled.