Which class of genes needs to be inactivated to facilitate cancer development?

To facilitate cancer development, the inactivation of tumor suppressor genes is critical. Tumor suppressor genes play a vital role in regulating cell division, repairing DNA, and controlling apoptosis (programmed cell death). When these genes are functioning properly, they prevent uncontrolled cell growth and help maintain the integrity of the genome.

In cancer, the inactivation or loss of these genes leads to a failure in these regulatory mechanisms, resulting in unchecked cell proliferation and the potential for tumor formation. For instance, well-known tumor suppressor genes such as TP53 and RB1, when mutated or deleted, contribute significantly to the progression of various cancers.

In contrast, oncogenes (which are often mutated forms of proto-oncogenes) promote cell division and survival, and their activation can lead to tumor formation. However, in normal circumstances, proto-oncogenes are vital for regular growth and function, and they don’t need to be inactivated; rather, they are typically overactive in cancer. The term "anti-oncogene" is another name sometimes used for tumor suppressor genes, but the primary focus in cancer development is on the inactivation of these protective genes.