Endometrial Cancer

Endometrial cancer is the most common gynaecological malignancy in high-income countries.

Most cases are Type I endometrioid tumours driven by estrogen signalling.

That makes Urolithin A especially relevant here.

Its strongest hormone-related mechanism is selective estrogen-receptor modulation.

The current evidence base is narrow but mechanistically strong.

It is centred on one detailed in vitro study and one adjacent endometriosis study.

There is no endometrial-cancer xenograft evidence.

There are no clinical trials.

Overview of the evidence

The main endometrial-cancer study screened 17 black-raspberry metabolites and constituents.

Urolithin A showed the strongest antiproliferative effect in ECC-1, Ishikawa, and HEC1A cells at 10 µM over 48 hours.

That matters.

The signal did not emerge from an isolated one-compound experiment.

It emerged from a head-to-head comparison.

Ellagic acid and Urolithin B were both less active at the same concentration.

That suggests the effect is specific to Urolithin A rather than a generic ellagitannin signal.

All of this evidence remains in vitro.

Why endometrial cancer is a biologically relevant setting

Type I endometrial cancer is often estrogen dependent.

Its growth is usually driven more by ERα than ERβ.

That balance matters.

ERα tends to promote proliferation.

ERβ tends to counter it through antiproliferative and pro-apoptotic signalling.

In many endometrial cancers, the balance shifts toward ERα dominance.

Urolithin A appears to push it back the other way.

As discussed on the Breast Cancer page, Urolithin A behaves like a context-dependent selective estrogen-receptor modulator rather than a simple estrogen blocker.

In endometrial cancer, that matters more than usual.

The main finding is not generic hormone suppression.

It is subtype-selective receptor remodelling.

G2/M cell-cycle arrest

Urolithin A caused G2/M arrest in endometrial-cancer cells.

Mechanistic work showed coordinated changes in several checkpoint regulators:

• Cyclin B1 — required for CDK1 activation at G2/M

• Cyclin E2 — involved in S/G2 progression

• p21 (CDKN1A) — broad CDK inhibitor that can block G2/M progression

• Phospho-cdc2 (Tyr15) — inactive CDK1 form, consistent with blocked mitotic entry

• CDC25B — phosphatase that normally activates CDK1

This pattern is useful.

It points to a reinforced checkpoint effect rather than a single-protein artefact.

Estrogen-receptor modulation — ERα down, ERβ up

This is the most distinctive endometrial finding in the current Urolithin A literature.

In estrogen-responsive endometrial-cancer cells, Urolithin A:

• lowered ERα mRNA

• raised ERβ mRNA

• raised progesterone receptor (PGR)

• raised pS2 (TFF1)

• raised GREB1

• lowered GRIP1 (SRC-2/NCOA2)

That profile is unusual.

It suggests Urolithin A is not acting as a blunt anti-estrogen.

It is reshaping estrogen-response signalling in a more selective way.

PGR matters because its expression is generally associated with a more differentiated and more hormonally responsive endometrial phenotype.

GRIP1 matters because it acts as an ERα coactivator.

Lower GRIP1 should further reduce ERα-driven transcription.

ERα knockdown confirmed the mechanism

The study also used ERα knockdown experiments.

When ERα was knocked down before Urolithin A exposure, the estrogen-response gene effects disappeared.

That is strong mechanistic support.

It means the receptor-level effects are actually ERα dependent.

This does not look like a non-specific cytotoxic signal.

It looks like direct engagement with endometrial estrogen biology.

Some activity remains without ERα

One finding adds nuance.

When ERα was already knocked down, Urolithin A still reduced proliferation further.

That suggests part of its effect does not depend on ERα.

The most likely explanation is the cell-cycle arrest programme.

That possibility matters because it raises the question of whether some activity could persist in lower-ER settings.

That has not yet been tested properly.

Why the berry-metabolite comparison matters

Many polyphenol papers show that a compound can inhibit cancer-cell growth.

That is common.

What stands out here is the direct comparison.

Urolithin A was tested against 17 black-raspberry-derived constituents and metabolites in the same experimental system.

It came out as the strongest antiproliferative compound.

That gives the result more weight.

It suggests Urolithin A is not just one more modestly active berry metabolite.

Endometriosis as adjacent evidence

Urolithin A has also been studied in endometriosis models.

Endometriosis is not cancer.

Still, the overlap is worth noting.

Both endometriosis and Type I endometrial cancer involve estrogen-driven tissue growth and relative resistance to apoptosis.

In vitro, Urolithin A and Urolithin B reduced the viability and integrity of endometriotic spheroids.

In a murine endometriosis model, Urolithin A reduced ectopic lesion growth.

This is not treatment evidence for endometrial cancer.

It is adjacent support for biological relevance in endometrial tissue.

Obesity-linked risk context

The original endometrial study was framed partly around obesity.

That is reasonable.

Obesity is the strongest modifiable risk factor for Type I endometrial cancer.

Adipose tissue increases peripheral estrogen production through aromatase activity.

It also contributes insulin resistance, leptin signalling, and chronic low-grade inflammation.

Those are all pro-carcinogenic pressures in the endometrium.

This broader context matters because Urolithin A also has reported effects on:

• AMPK activation

• insulin sensitivity

• inflammatory signalling

• adipose-tissue inflammation

That does not create treatment evidence.

It does support a prevention-oriented rationale in higher-risk metabolic settings.

What remains unknown

• no endometrial-cancer xenograft or other tumour-model data

• no clinical trials in endometrial-cancer patients

• no data yet in Type II serous or clear-cell endometrial cancers

• no direct combination work with progestins, aromatase inhibitors, or standard chemotherapy

• no direct combination work with pembrolizumab or other immunotherapy agents

• no proof yet that ERα and ERβ remodelling translates into in vivo tumour control

Bottom line

Endometrial cancer is a narrow but mechanistically interesting Urolithin A evidence area.

The strongest reason to care is not the size of the evidence base.

It is the fit between the mechanism and the disease biology.

The current data support three main points:

• Urolithin A is strongly antiproliferative in the main published endometrial-cancer model

• it causes credible G2/M arrest through multiple checkpoint proteins

• it shifts estrogen signalling away from ERα dominance and toward ERβ-associated biology

That makes endometrial cancer one of the cleaner hormone-biology settings for Urolithin A.

The evidence is still entirely preclinical.

There is no in vivo tumour evidence yet.

There is no clinical evidence yet.

Evidence level summary

References

Urolithin A suppresses the proliferation of endometrial cancer cells by mediating estrogen receptor-α-dependent gene expression https://pmc.ncbi.nlm.nih.gov/articles/PMC5144574/

Effect of urolithins A and B on ectopic endometrial growth in a murine model of endometriosis https://pubs.rsc.org/en/content/articlelanding/2021/fo/d1fo01702k

Urolithins: the colon microbiota metabolites of ellagitannins as endocrine modulators — implications for breast and endometrial cancer https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2021.800990/full

Unveiling the potential of Urolithin A in cancer therapy — mechanistic insights to future perspectives https://pmc.ncbi.nlm.nih.gov/articles/PMC12188533/