Anticancer Mechanisms

Shikonin acts across several cancer hallmarks at once.

Its strongest mechanisms cluster around metabolism, cell death, and endocrine signalling.

PKM2 inhibition and metabolic stress

The best-established mechanism is inhibition of pyruvate kinase M2.

PKM2 supports aerobic glycolysis in tumour cells and helps divert carbon into biomass production.

When shikonin inhibits PKM2, cancer cells lose glycolytic efficiency, lactate output falls, ATP pressure rises, and anabolic support weakens.

This has been reported across breast, bladder, liver, oesophageal, and pancreatic models.

Apoptosis and necroptosis

Shikonin can trigger classic mitochondrial apoptosis.

That includes mitochondrial membrane depolarisation, cytochrome c release, caspase activation, and PARP cleavage.

It can also trigger necroptosis.

That route depends on RIPK1 and RIPK3 rather than caspases.

This is one reason it remains interesting in apoptosis-resistant disease.

Ferroptosis in selected settings

In anaplastic thyroid-cancer models, shikonin has been linked to ferroptosis.

That finding is newer and much less replicated than the PKM2 work.

It still matters because it adds a third distinct cell-death route.

Estrogen-receptor disruption

In ER-positive breast-cancer models, shikonin:

• suppresses ERα-mediated transcription

• promotes ERα protein degradation

• downregulates GPER

• reduces EGFR and p-ERK signalling downstream

• may inhibit steroid sulfatase activity inside tumour tissue

That is not a single endocrine effect.

It is multi-level pressure across nuclear receptor, membrane receptor, local hormone generation, and growth signalling.

Cell-cycle arrest

Across multiple cancer types, shikonin can arrest cells in G2/M.

This effect appears partly linked to p21 upregulation and reduced ERK-driven growth signalling.

That adds a broad anti-proliferative layer beyond its metabolic effects.

EMT and invasion suppression

Cervical and breast-cancer work suggests shikonin can reduce epithelial-mesenchymal transition.

The reported signals include lower Snail, higher E-cadherin, miR-183-5p modulation, and lower matrix-remodelling pressure.

These findings remain early.

Bottom line

Shikonin is best understood as a multi-pressure compound.

It does not only poison tumour cells.

It interferes with how they fuel themselves, how they avoid death, and in some settings how they use hormone signalling to grow.

Key references

Ahmad F et al. (2024). Shikonin in breast cancer treatment: a comprehensive review. Journal of Pharmacy and Pharmacology.
https://academic.oup.com/jpp/article/76/8/967/7656703

Lv C et al. (2021). Shikonin inhibits ESCC tumour growth by suppressing PKM2/STAT3. Journal of Cancer.
https://www.jcancer.org/v12p4830.htm

Shikonin differentially regulates glucose metabolism via PKM2 and the Warburg Effect. Life Sciences / ScienceDirect.
https://www.sciencedirect.com/science/article/abs/pii/S0024320520315496

Li Z et al. (2018). PKM2 inhibitor shikonin overcomes cisplatin resistance — necroptosis in bladder cancer. PMC.
https://pmc.ncbi.nlm.nih.gov/articles/PMC6231221/

Yang J et al. (2019). ER-mediated anti-tumor effects — GPER and EGFR signalling. European Journal of Pharmacology.
https://www.sciencedirect.com/science/article/abs/pii/S0014299919306193

Han X et al. (2010). Antiestrogen activity: ERα suppression in breast cancer. Life Sciences.
https://pubmed.ncbi.nlm.nih.gov/19760501/

Shikonin inhibits cancer through p21 upregulation and apoptosis induction. Frontiers in Pharmacology (2020).
https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2020.00861/full

Shikonin inhibits growth of anaplastic thyroid carcinoma cells via ferroptosis. Heliyon / ScienceDirect (2024).
https://www.sciencedirect.com/science/article/pii/S2405844024103222

Frontiers in Pharmacology (2025). Shikonin in female reproductive cancers — EMT/Snail mechanism.
https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2025.1627124/full