Cancer Evo-Dev, a novel hypothesis derived from studies on hepatitis B virus-induced carcinogenesis

Non-resolving inflammation, which may be maintained by infection, pollution, and metabolic stimulants and their interactions with immunogenetic predisposition, provides a fertile field for cancer development. This is strongly evident in hepatocellular carcinoma. Here, the framework of a hypothesis called Cancer Evo-Dev is presented, based on the advances in hepatitis B virus-induced hepatocarcinogenesis. Several aspects central to this theory are as follows: (1) immune imbalance caused by the interaction of immunogenetic predispositions and hepatitis B virus infection maintains non-resolving inflammation; (2) active inflammation executants promote mutations in viral and host genomes via disbalancing mutagenic forces including cytidine deaminases and mutation-repairing forces including uracil-DNA glycosylases, thus promoting cancer-related somatic mutations and viral mutations; (3) a small percentage of the cells whose somatic mutations alter the survival signalling adapt to the inflammatory microenvironment, de-differentiate via demethylating role of cytidine deaminases, and reversely develop into tumor-initiating cells (TICs); (4) under the cultivation of some factors like POSTN from tumor-infiltrating fibroblasts and M2 macrophages, TICs acquire the stemness, cancer-stem cells obtain distinct metastatic and drug-resistant potentials under the selection pressure from distinct microenvironments; (5) glycolysis persistence in the presence of oxygen provides essential energy for cell survival and the raw material for DNA synthesis. Thus, cancer development is characterized by an evolutionary process of “mutation-selection-adaptation”. The framework of Cancer Evo-Dev can be verified in other cancers. Cancer Evo-Dev lays theoretical foundation for understanding the mechanisms by which inflammation promotes cancer development, and it also plays a role in specific prophylaxis, prediction, and targeted treatment of cancers