Tomoaki Shirakawa
- kawaokashinpei3
- 3 days ago
- 2 min read
Selected journal : Nature
Ageing promotes metastasis via activation of the integrated stress response
What is the main question of the paper?
How does physiological ageing alter tumor evolution in KRAS-mutant lung adenocarcinoma?
How did the anthor address the question?
■Step1
They induced the same KRAS-mutant lung adenocarcinoma model in young and aged mice and compared the pattern of tumor progression.
The authors induced lung adenocarcinoma in young and aged KP mice using the same approach. They found that aged mice had lower primary tumor burden and reduced proliferation, but showed more malignant progression to adenocarcinoma and increased lymph node and distant metastasis. This suggests that ageing does not simply accelerate primary tumor growth, but shifts tumor progression from primary tumor expansion toward acquisition of metastatic ability.
■Step2
They identified activation of the ISR–ATF4 pathway in tumor cells from aged mice.
The authors compared tumor cells from young and aged mice using RNA-seq and ATAC-seq. These analyses showed that tumor cells from aged mice had transcriptional and chromatin changes related to the integrated stress response. Among these changes, ATF4 was identified as a central factor, and aged tumor cells showed a state in which ATF4 signaling was more persistently activated.
■Step3
They demonstrated a causal link between ATF4 and metastatic ability.
Pharmacological or genetic inhibition of ATF4 reduced anoikis resistance and metastatic ability in tumor cells from aged mice. Conversely, overexpression of ATF4 in tumor cells from young mice induced metastatic ability. In human lung adenocarcinoma datasets, ATF4 expression was also higher in tumors from older patients and was associated with advanced stage and poor prognosis.
What is the strength of the paper?
The strength of this paper is that it evaluates the effect of ageing not simply by asking whether tumors become larger, but by asking how the mode of tumor progression itself changes. Starting from the paradoxical observation that aged mice show reduced primary tumor growth but increased metastasis, the authors identify ISR–ATF4 activation as an underlying mechanism and then demonstrate its causal role through ATF4 inhibition and overexpression. Finally, by linking ATF4 expression in human lung adenocarcinoma to older age, advanced stage, and poor prognosis, they connect the mouse findings to a clinically relevant context.
Comment
It is very interesting that they are addressing the clinically important but previously unexplained question of why metastasis increases with advancing age. Furthermore, the overall structure of the paper follows a very clear progression: observation of the phenomenon → identification of causes and mechanisms → verification of necessary and sufficient conditions through intervention targeting the identified
Comment by Yuki Nakamura
