Mechanisms Involved in Carcinogenesis

The initiation of human cancer is primarily driven by carcinogenic substances including chemicals, radiations, viruses, and parasites. The carcinogenesis mechanism is a complex process in which cellular DNA mutations contribute to the initiation, which is the first step, and seems to be irreversible. The second stage is promoted over a long period and is largely reversible in initial stages. The key events for the carcinogenesis process tend to be epigenetic. Cancer genes are classified by their ability to regulate oncogenesis as the dominant oncogenes and recessive tumor suppressors. Activation of oncogenes may be due to the occurrence of mutations in these genes. Besides, a single sufficiently activated oncogene will initiate the entire process of the cancerous transition of a normal cell. Their function in cancer growth has been widely demonstrated in experimental studies involving viruses and chromosome translocations. Furthermore, micro-RNAs (miRNAs) are preserved throughout development and regulate gene expression during cell proliferation, growth, and even in cancer progression by an unidentified control mechanism. miRNAs also play a crucial function in malignancy. The discovery and elucidation of the carcinogenic molecular pathways of carcinogens provide a deeper understanding of how genetic manipulation influences the mechanism of neoplastic development. The current chapter explains the different mechanisms involved in the carcinogenesis process.