Tumours with PI3K activation are resistant to dietary restriction

NY Kalaany, DM Sabatini - Nature, 2009 - nature.com
NY Kalaany, DM Sabatini
Nature, 2009nature.com
Dietary restriction delays the incidence and decreases the growth of various types of
tumours, but the mechanisms underlying the sensitivity of tumours to food restriction remain
unknown. Here we show that certain human cancer cell lines, when grown as tumour
xenografts in mice, are highly sensitive to the anti-growth effects of dietary restriction,
whereas others are resistant. Cancer cells that form dietary-restriction-resistant tumours
carry mutations that cause constitutive activation of the phosphatidylinositol-3-kinase (PI3K) …
Abstract
Dietary restriction delays the incidence and decreases the growth of various types of tumours, but the mechanisms underlying the sensitivity of tumours to food restriction remain unknown. Here we show that certain human cancer cell lines, when grown as tumour xenografts in mice, are highly sensitive to the anti-growth effects of dietary restriction, whereas others are resistant. Cancer cells that form dietary-restriction-resistant tumours carry mutations that cause constitutive activation of the phosphatidylinositol-3-kinase (PI3K) pathway and in culture proliferate in the absence of insulin or insulin-like growth factor 1. Substitution of an activated mutant allele of PI3K with wild-type PI3K in otherwise isogenic cancer cells, or the restoration of PTEN expression in a PTEN-null cancer cell line, is sufficient to convert a dietary-restriction-resistant tumour into one that is dietary-restriction-sensitive. Dietary restriction does not affect a PTEN-null mouse model of prostate cancer, but it significantly decreases tumour burden in a mouse model of lung cancer lacking constitutive PI3K signalling. Thus, the PI3K pathway is an important determinant of the sensitivity of tumours to dietary restriction, and activating mutations in the pathway may influence the response of cancers to dietary restriction-mimetic therapies.
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