5. Hallmarks of cancer (part 2)

The hallmarks of cancer are the 6 key traits that cancer cells share in common; they are the properties that make them cancerous. In the previous video we learned about the first two - self sustained growth and insensitivity to anti-growth signals.

In this video we cover the last 4:

Tissue invasion and metastasis: cancerous cell need to be able to break free of the extracellular matrix in tissues, enter the bloodstream or lymphatics, leave the blood stream and seed in another tissue/organ.

Limitless replicative potential: most cells have a limit to the number of times they can divide. This is decided by the length or telomeres - portions of non coding DNA at the end of chromosomes that act as a protective cap, and get shorter with each division. Cancers must be able to activate enzymes that maintain the length of telomeres. To learn more about telomeres and the 'end replication problem' have a look at this video: https://www.youtube.com/watch?v=AJNoTmWsE0s

Sustained angiogenesis: as cancers grow, they need to keep a steady supply of nutrients. This means stimulating processes that lead to the growth of new blood vessels that are able to supply them with their nutritional needs.

Avoiding apoptosis: cells which have damaged DNA are normally detected and mechanisms lead them to self destruct in order to avoid passing on mutations to their daughter cells. Mutations in genes coding for proteins involved in this process can allow cancerous cells to ignore these signals.

A more recent version of the hallmarks of cancer have added a further 4 hallmarks (making 10 in total) - these will be covered in a later video.

References
Hanahan and Weinberg, 2000 The hallmarks of cancer Cell, 100 (2000), pp. 57-70

Видео 5. Hallmarks of cancer (part 2) канала Oncology for Medical Students