Cancer cells grow differently depending on how stiff the collagen around them is: on hard collagen, they turn on a growth switch (YAP/TAZ); on soft collagen, they use a different switch (MRTF/SRF).
Scientific Claim
Matrix stiffness modulates tumor cell proliferation through integrin-mediated activation of the Hippo-YAP/TAZ pathway on stiff collagen matrices and MRTF/SRF on soft matrices.
Original Statement
“On a hard surface, the Hippo pathway is involved in the proliferation of tumor cells, consisting of three main components: large tumor suppressor 1/2 (LATS1/2), yes-associated transcriptional regulator/tafazzin (YAP/TAZ) and mammalian Ste20-like kinases 1/2 (MST1/2)... On a soft surface such as extracellular matrix protein (collagen), the interaction of superfluous collagens to integrin β subunit activates Src family kinases (SFKs) and focal adhesions’ formation... ultimately stimulating the progression and contraction of cancer cells by accelerating downstream proteins, AP-1 (oncogene c-Jun/c-Fos) via FAK, PI3K, Rac, PAK, MEK, and ERK... This system eventually contributes to the tumor cells’ proliferation by accelerating downstream proteins, AP-1 (oncogene c-Jun/c-Fos) via FAK, PI3K, Rac, PAK, MEK, and ERK... via the myocardin-related transcription factor (MRTF)/serum response factor (SRF) complex.”
Evidence Quality Assessment
Claim Status
overstated
Study Design Support
Design cannot support claim
Appropriate Language Strength
association
Can only show association/correlation
Assessment Explanation
The review synthesizes data from cell culture models but does not establish causation in vivo. 'Modulates' and 'activates' imply direct control, which exceeds the evidence level of a narrative review.
More Accurate Statement
“Matrix stiffness is associated with differential activation of tumor cell proliferation pathways: the Hippo-YAP/TAZ pathway on stiff collagen matrices and the MRTF/SRF pathway on soft collagen matrices based on prior in vitro mechanobiology studies.”
Evidence from Studies
Supporting (0)
Contradicting (1)
This study talks about where collagen comes from and how it's used in medicine, but it doesn't say anything about how stiff or soft collagen affects cancer cell growth or the inside signals they use.