PTEN and Cancer
How a tumor suppressor keeps cell growth in check — and what happens when it is lost
PTEN is one of the most frequently disrupted tumor suppressors in human cancer, second only to TP53. When it works, it acts as a brake on cell growth. When it is lost, that brake comes off — and cells grow, divide, and survive when they should not.
How PTEN suppresses tumours
PTEN is a lipid phosphatase. Its main job is to strip a phosphate from PIP3, converting it back to PIP2. PIP3 is the "grow and survive" second messenger that PI3K produces, so by erasing it PTEN keeps the PI3K/Akt/mTOR pathway switched off. Encoded by the PTEN gene at 10q23.31, the protein is 403 amino acids (~47 kDa; UniProt P60484).
PTEN also carries a weaker protein phosphatase activity and has roles in the nucleus, but its tumor-suppressor function depends mostly on the lipid phosphatase reaction at the membrane. Take that reaction away and the pathway downstream never turns off.
How PTEN is lost in cancer
PTEN is silenced in several ways at once across different tumours: point mutations that break the catalytic pocket, deletion of one or both gene copies, epigenetic silencing through promoter methylation, and disruption of the proteins that normally stabilise it.
Unlike a classic "two-hit" tumor suppressor, PTEN is haploinsufficient — losing a single functional copy, or even a modest drop in protein level, is enough to push cells toward cancer. Small changes in PTEN dose produce measurable changes in tumour risk.
Cancers where PTEN loss is common
| Tumour type | How PTEN is typically affected |
|---|---|
| Prostate | Frequent deletion/loss; associated with progression |
| Endometrial | One of the earliest and most common events |
| Glioblastoma | Common deletion; drives PI3K/Akt activity |
| Breast | Loss linked to PI3K-pathway activation and resistance |
| Melanoma | Loss cooperates with BRAF signalling |
Cowden syndrome and PTEN hamartoma tumor syndrome
Inherited (germline) PTEN mutations cause PTEN hamartoma tumor syndrome (PHTS), of which Cowden syndrome is the best known. Around 80% of people with Cowden syndrome carry a PTEN mutation, and they face raised lifetime risks of breast, thyroid, and endometrial cancer — which is why PTEN testing guides screening in these families.
Why it matters for treatment
Because PTEN loss switches the PI3K/Akt/mTOR pathway on, tumours that have lost PTEN are a rationale for PI3K, AKT, and mTOR inhibitors, and PTEN status is studied as a biomarker of who responds. The pathway is a heavily pursued drug target, though resistance remains a real obstacle.
Studying PTEN loss in the lab
Most PTEN cancer biology is dissected with a small toolkit: detect the protein with an anti-PTEN antibody, model its loss with PTEN siRNA, run phosphatase and inhibitor assays on recombinant PTEN protein, or block its activity pharmacologically with SF1670. All are supplied for laboratory research use only.
Frequently asked questions
Is PTEN an oncogene or a tumor suppressor?
PTEN is a tumor suppressor. It removes the PIP3 growth signal that PI3K produces, so losing PTEN — not gaining it — is what promotes cancer.
Which cancers most often lose PTEN?
PTEN loss is especially common in prostate, endometrial, glioblastoma, breast, and melanoma, among others. It is one of the most frequently inactivated tumor suppressors overall.
What is PTEN haploinsufficiency?
It means losing just one functional copy of PTEN (or a partial drop in protein level) is enough to promote tumours — PTEN does not need to be fully deleted to matter.
What is Cowden syndrome?
Cowden syndrome is the best-known PTEN hamartoma tumor syndrome, caused by an inherited PTEN mutation in about 80% of cases, with increased lifetime risk of breast, thyroid, and endometrial cancer.
Key references
- 1.Li J, Yen C, Liaw D, et al. “PTEN, a putative protein tyrosine phosphatase gene mutated in human brain, breast, and prostate cancer.” Science. 1997. DOI ↗
- 2.Steck PA, Pershouse MA, Jasser SA, et al. “Identification of a candidate tumour suppressor gene, MMAC1, at chromosome 10q23.3 that is mutated in multiple advanced cancers.” Nature Genetics. 1997. DOI ↗
- 3.Hollander MC, Blumenthal GM, Dennis PA. “PTEN loss in the continuum of common cancers, rare syndromes and mouse models.” Nature Reviews Cancer. 2011. DOI ↗
- 4.Glaviano A, Foo ASC, Lam HY, et al. “PI3K/AKT/mTOR signaling transduction pathway and targeted therapies in cancer.” Molecular Cancer. 2023. DOI ↗
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Related research reagents
Tools for studying PTEN in the lab — research use only.
Anti-PTEN Antibody
Rabbit anti-PTEN, validated for WB / IHC / IF
From $279.00 USD · Preorder
PTEN siRNA
PTEN-targeting siRNA for gene knockdown
From $149.00 USD · Preorder
Recombinant PTEN Protein
Active full-length human PTEN, lyophilized for stable shipping
From $395.00 USD · Preorder
SF1670
Selective PTEN phosphatase inhibitor
From $349.00 USD · Preorder
Educational content based on peer-reviewed research — not medical advice. Reagents are supplied for laboratory research use only and are not for human or veterinary use.