Page 11 - Helicobacter pylori and Gastric Cancer: From Tumor microenvironment to Immunotherapy

prostate, liver, lung, breast, cervix, colorectal manifestations (2). Cancer can arise from any form of body tissue and occurs when a typical cell acquires six core biological hallmarks which turn it into a tumor cell. Hanahan et al.(3, 4), describe these six core hallmarks of cancer to include the ability of tumor cells to: 1) sustain continuous proliferation through constitutive activation of proliferative signaling pathways or disruption of negative feedback mechanism on cell proliferation, 2) to evade growth suppression through the inactivation of tumor suppressor genes, which in normal physiology generally turn of an increased signaling and control the cell cycle progression, 3) to resist cell death by the loss of pro-apoptotic factors and the upregulation of anti-apoptotic factors, 4) to enable replicative immortality through the extension of the telomeric DNA at the ends of the chromosome by telomerase enzymatic activity, 5) to stimulate angiogenesis to provide access of the tumor to nutrients and oxygen and for removal of metabolic wastes, 6) to undergo invasion and metastasis whereby tumor cells alter their shape and lose their adherence to other extracellular matrix and cells (Fig. 1A)(3).
These six ‘core’ hallmarks are somewhat artificial as it is now becoming evident that tumor cells can also acquire other typical hallmarks of which reprogramming of their energy metabolism, using glycolysis to produce energy even under aerobic conditions, is maybe the most evident. The latter are sometimes denominated as “emerging hallmarks.”
Figure 1. The cancer hallmarks (A) Schematic depiction of the six ‘core’ properties typically acquired by a tumor cell during its multistep development. These six properties are sustaining proliferation, evading growth suppression, resisting cell death, enabling replicative immortality, inducing angiogenesis, and activating invasion and metastasis. (B) Furthermore, tumor cells acquire two emerging hallmarks, reprogramming energy metabolism and avoiding the immune system, and two enabling hallmarks, genome instability, and tumor-promoting inflammation. (Adapted from reference)(3)
Chapter 1
General introduction
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