In a popular article it is mentioned that in centrifugal experiments with cancer cells that

When subjected to microgravity-conditions, the cancer cells were unable to sense each other and therefore had a very hard time coming together.

which is because

[...] the process through which cancer grows and spreads would seem to indicate that there is a means through which the cells are able to sense each other and gravitate together to form a tumor.

I would now be interested in the role of such fundamental forces in cell-signaling.

How does gravity interact with cell-signaling and lead to the 'gravitation' of tumor cells towards one another?

To my knowledge, cell signaling is a bunch of processes that involve the propagation of electrical signals by chemical means, so I am rather surprised that gravity would play any role in this.

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    $\begingroup$ That article looks like incoherent gibberish, to be honest. Very little in it makes any kind of sense. The statement that "the only way cancer cells could sense each other is through mechanical forces" is nonsense. You can't get microgravity with a centrifuge - all you can do is put the cells in higher "gravity" and then reduce the "gravity" back to 1. And so on. Undoubtedly the actual scientist knows these things, but the person who wrote the article clearly didn't understand what they were being told. Trying to figure out the reality is probably a waste of time, until Chou publishes. $\endgroup$
    – iayork
    Dec 3, 2019 at 20:08
  • $\begingroup$ @iayork: Yes, I was very confued upon reading it as well. The fact that the article on Universetoday is essentially a copypaste of the UTS article, and also misspells Chou's name is not very indicative of quality science journalism. However I was just curious if in the biology world there is some indication that this might be a real effect and what its provenance should be. $\endgroup$ Dec 3, 2019 at 22:32
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    $\begingroup$ It actually looks like the original article was in fact written by Chou, and is still just as confusing. Statements like "By disabled, I mean they either die or float off because they can no longer hold on" sound a bit like xkcd.com/1217 to me, and comes with no citation, nor does any of Chou's previously published work have any relevance to this. It kind of sounds like they shook up some cells growing in a dish and they fell off the dish. $\endgroup$
    – Bryan Krause
    Dec 3, 2019 at 23:03
  • $\begingroup$ Microgravity can affect the mechanical forces of the cell and alter gene expression; there are some reports on this. However, the statements made in the popsci article are ridiculous. $\endgroup$
    Dec 4, 2019 at 10:50
  • $\begingroup$ @WYSIWYG: I'm happy to upvote any credible source that goes beyond "Gravity affects pathways somehow". I'm interested in the microphysics, you could say. $\endgroup$ Dec 4, 2019 at 11:14

1 Answer 1


It is reported that 99 genes are significantly upregulated in presence of normal gravity, whereas in absence of gravitational force no gene expression is seen in case of T cell activation. Research article attached concluded that gravity is important for regulating various essential T-cell activation signalling pathways, which play key role in cell proliferation and apoptosis.

Transcription factors like NF-kB, CREB, ELK, AP-1, and STAT are responsible for tumor cell development. And NF-kB and CREB showed gravity-mediated gene expression. As, the PKA signaling pathway regulates expression of these transcription factor, so it means that gravitational force moderates PKA signalling. And PKA signalling also mediates tumorigenesis. So, by regulating various cell signalling pathways, gravity controls the tumor cells.

Gravity also modulates the activity of Epidermal growth factor, which are implicated in tumor progression. (Via: https://www.ncbi.nlm.nih.gov/pubmed/7757250)

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  • $\begingroup$ Thank you for this, but your answer doesn't answer my question. You say 'So, by regulating various cell signalling pathways, gravity controls the tumor cells.' and I asked 'How are cell signaling pathways regulated by gravity?' $\endgroup$ Dec 4, 2019 at 0:03
  • $\begingroup$ The article (summary?) you've linked gives a hint at the end: "The physical mechanisms by which the T cells respond to gravity remain an intriguing enigma [...]". However the article is from 2005, so maybe there is some more recent insight? Or are we simply not there yet... $\endgroup$ Dec 4, 2019 at 0:05
  • $\begingroup$ As gravity controls the expression of various Transcription factors, which are responsible for proliferation and death of cells by regulating signalling pathways. So this effects progression of tumor cells. $\endgroup$ Dec 4, 2019 at 0:45
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    $\begingroup$ @TwinkleSheen You're repeating the same thing. "Controlling transcription factors" is not a mechanism for gravity to have an influence, it's just a synonym for "regulating cell signalling". $\endgroup$
    – Bryan Krause
    Dec 4, 2019 at 1:30

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