Comments on: Tumors as ecosystems

By: Twistys

Twistys — Tue, 16 Feb 2010 09:55:01 +0000

“tumor, by the time we can detect it, is a collection of many cells, at least billions of them, and those cells are not all the same.”

What about the T-cells that are said to be the fastest tumor cells to spread? My dad got them and it was really fast.

By: Peer

Peer — Tue, 09 Feb 2010 19:44:25 +0000

Considering epigenetic changes, cell cycle progression, activation/differentiation status, transcript and metabolite levels etc. I don’t think that there are two identical cells in the body. Any of those factors may make it more favorable for one cell over another to eventually progress into a tumor.

You are probably right about the heterogeneity of HIV vs. tumors. HIV is likely far more heterogeneic than tumors at the genome and gene transcript level. Considering a tumor or even a cell line as a population, there are likely to be differences within the population, although the population as a whole might look very similar (think bell shaped curve). However due to the genetic instability of tumors, the existence of quasispecies in cancer is likely.

REFS:
Cahill et al, 1999. Genetic instability and darwinian selection in tumours.
R.V. Solé, 2003 Phase transitions in unstable cancer cell populations

By: Dunbar

Dunbar — Mon, 08 Feb 2010 04:25:46 +0000

There aren’t two identical cells in the body? Also, I think the heterogeneity in HIV is qualitatively and quantitatively different from that of tumours.

By: Peer

Peer — Thu, 04 Feb 2010 18:49:19 +0000

I think tumors and HIV are both quasispecies (http://www.cell.com/trends/ecology-evolution/abstract/0169-5347%2892%2990145-2)

Also, I don’t think there are two identical cells in the body, so what is said about tumors can be said about any cell.

Here’s my CTL analogy:
Each tumor mass is a herd or colony, (after metastasis) every organ is a potential watering hole and CTLs are blinded hunters on a safari trying to kill a lion in sheep’s clothing.