**4. Molecular basis of cancer**

All cancers display eight fundamental changes in cell physiology, which are considered the hallmarks of cancer.


#### **Table 3.**

*Chronic inflammatory states and cancer.*

These changes are:

	- Protooncogenes: Proto oncogenes have multiple roles but all participate at some level in signaling pathways that drive proliferation.
		- Normal cellular genes, whose products promote cell proliferation.
		- Unmutated version.
		- Proto-oncogenes may encode growth factors, growth factor receptors, signal transducers, transcription factors, or cell cycle components (**Table 4**).
	- Oncogenes:
		- Genes that promote autonomous cell growth in cancer cells are called oncogenes.
		- Mutant versions of proto-oncogenes.
		- Encode proteins called oncoproteins.
		- Have the ability to promote cell growth in the absence of normal growth promoting signal (**Table 5**) [7–10].
	- Tumor suppressor gene:
		- Genes negatively regulate proliferation. Apply brakes or arrest cell cycle to cell proliferation.
		- Abnormalities in these genes lead to failure of growth inhibition.
		- Effect on the regulation of the cell cycle on promote apoptosis, and sometimes do both.
		- Mutation in tumor suppressor gene causes unregulated cell growth.
		- First tumor-suppressor protein discovered was the Retinoblastoma protein (pRb) in retinoblastoma (**Table 6**) [11–14].
