2.1 Cellular Oncogenes

The DNA and RNA tumor viruses characterized in the 1970s provided cancer biologists with a simple and powerful theory of how human tumors could arise.
It was thought that….
Viruses that occurred commonly in the human population might, with some frequency, infect susceptible tissues and cause the transformation of infected cells.
However!!!
Most types of human cancer clearly do not spread from one individual to another as an infectious disease.
Significant clusters of cancer cases - mini-epidemics of disease - are hard to find.
In rare cases (mouse models have shown)
Endogenous retroviruses can explain tumor development in the absence of infectious viral spread.
Most human cancers do not contain viruses
Attempts undertaken during the 1970s to isolate viruses from most types of human tumors were unsuccessful.
From hundreds or more tumor types encountered in the oncology clinic
only two commonly occurring tumor types in the Western world could clearly be tied to specific viral causative agents
cervical carcinomas
hepatomas (liver carcinomas)
The cell genome is rich source of the genes that drive human cancer
The cellular genome has tens of thousands of genes.
A large catalog of cellular cancer-causing genes has now been assembled over the ensuing decades
These are referred to as either oncogenes or tumor suppressor genes
These genes derive from early efforts to find infectious cancer causing agents in human populations.
Are endogenous retroviral genomes present in the human genome able to cause cancer?
The human genome contains relics of ancient germ-line infections that occurred 5 million years ago and earlier in ancestral primates.
As much as 8% of the human genome derives from endogenous retroviral genomes
only several of the approximately 40,000 retrovirus-derived segments have ever been shown to be genetically intact and capable of producing retrovirus particles.

[@selinozyldrm8527]

Nice explanation Dr, thanks for the lecture!

[@abhishekpawarpoems]

Wtf all irrelevant

[@UWSMarkTemple]

Oh well, I hope you find what you're looking for elsewhere...

[@alexanderdiederichs7332]

@@UWSMarkTemple Please don't get demotivated by critical comments I really like your explanation and it helps greatly for self-study. Of course, no online course can be complete, but for me the most important thing is that lectures are interesting and informative. I think you did a great job in making learning fun :), thanks for providing it for free!