Final answer:
Cancer cells and transformed cells in culture share the ability to grow indefinitely, the lack of contact inhibition, altered intercellular communication, and often become invasive due to genetic alterations affecting genes like proto-oncogenes and tumor-suppressor genes.
Step-by-step explanation:
Properties Shared by Cancer Cells and Transformed Cells in Culture
Cancer cells and transformed cells in culture share several unique properties that distinguish them from normal cells. One major characteristic is their ability to grow indefinitely when the culture medium is replenished, which confers a kind of immortality to these cells. This occurs because transformed cells and cancer cells often undergo chromosomal abnormalities, rearrangements, and deletions, resulting in the loss of contact inhibition and the capacity to grow without solid support. These cells continue to grow and divide even when they reach confluence, unlike normal cells which stop dividing due to contact inhibition. Moreover, biological differences such as the lack of gap junctions, and fewer cadherens and integrins in their membranes, impair intercellular communication and adherence to the extracellular matrix. These deficiencies can contribute to the cells' invasive and metastatic behavior in vivo.
Famous examples of cancer cell lines include the HeLa cell line, derived from human cervical cancer cells, which have been growing for decades in laboratories around the world. Transformations such as these are multi-stage processes involving genetic damage to proto-oncogenes and tumor-suppressor genes, as illustrated in the transformation of a normal cell into a cancer cell (Figure 21.7.2). A mutation can deactivate tumor suppressor genes, leading to uncontrolled cell growth and division, thereby increasing cancer risk.