Introduction
Tumorigenesis is a multistep genetic process in which normal cells acquire progressive genetic and epigenetic alterations, leading to uncontrolled proliferation, survival advantage, invasion, and metastasis. This topic covers the cellular and molecular features of the cancer cell, driver mutations, proto-oncogenes and oncogenes, tumor suppressor genes, other genetic mechanisms of tumorigenesis, and chronic myeloid leukemia (CML) with the BCR-ABL marker as the model of molecularly targeted therapy and its monitoring.
Cancer is fundamentally a genetic disease of somatic cells, caused by accumulation of mutations that affect genes regulating:
- cell cycle,
- apoptosis,
- DNA repair,
- cell differentiation,
- cell–cell interaction.
General cellular and molecular characteristics of the cancer cell
Cancer cells show a characteristic set of biological properties, often referred to as the hallmarks of cancer.
Key cellular characteristics
Cancer cells differ from normal cells by:
- autonomous growth signaling,
- resistance to growth inhibition,
- evasion of apoptosis,
- unlimited replicative potential,
- genomic instability,
- ability to invade and metastasize.
Molecular characteristics
- Persistent activation of growth-promoting pathways.
- Inactivation of growth-inhibitory mechanisms.
- Defects in DNA repair → accumulation of mutations.
- Altered metabolism (aerobic glycolysis – Warburg effect).
- Ability to induce angiogenesis.
- Immune evasion.