20.1 : What is Cancer?

Cells and tissues must meticulously coordinate their activitiesfor the normal functioning of the human body. Therefore, they exhibit socially responsible behavior - resting, growing, dividing, differentiating, or dying - for the organism’s benefit. Cancer arises when cells divide uncontrollably and invade other tissues or organs.

Although people have known about cancerfor centuries, it was only in 1761that Giovanni Morgagni of Padua performed a detailed autopsy of patients who died from cancer. His findings laid the foundations of the scientific discipline called Oncology, the study of cancer. To date, several scientists continue to increase our understanding of cancer and its pathology.

Cancer cells have two heritable characteristics: (1) They reproduce in defiance of the normal regulation on cell growth and division; (2) They invade and colonize territories of other cells and tissues. Cancer is a disease caused by genetic alterations. In most cases, mutations in the cell cycle regulation genes allow a cell to divide at the expense of the neighboring cells and negatively impact the host’s survival. However, cancer-causing mutations build up gradually over the organism’s lifetime. Therefore, most cancer cases are not diagnosed early in life.

In order to facilitate cancer research, several cell lines and model systems are used in cancer laboratories, while new tools are always under development. Cell lines are the cells derived from cancer patients and effectively “immortalized.” Most common examples include HeLa, OVCAR-3, and LNCaP cell lines. These cell lines are commonly used across laboratories to understand cancer pathology and aid in drug discovery. Also , several transgenic, knockout, and knock-in mice mouse models have been developed to study the onset and progression of cancer. They also aid in drug discovery, testing the drug efficacy and toxicity.