New research reveals that SLC30 transporters in breast cancer play a decisive role in driving hormone-independent tumor growth. While scientists have extensively studied the SLC39 (ZIP) family, the signaling functions of SLC30 transporters (ZnT) were previously unclear. This recent study highlights how SLC30A1, SLC30A5, and SLC30A9 modulate the AKT pathway to sustain oestrogen receptor-positive (ER+) disease.

Zinc serves as a vital secondary messenger that regulates intracellular signaling homeostasis. Specifically, these transporters control the PTP/AKT/ESR1 pathway by modulating zinc-dependent inhibition of PTP phosphatases. Consequently, this mechanism promotes cellular proliferation even in the absence of traditional hormonal triggers. Moreover, the study demonstrates that ESR1 directly represses SLC30 transcription, creating a complex regulatory feedback loop.

The Prognostic Paradox of SLC30 Transporters in Breast Cancer

The study uncovered a complex relationship between transporter expression and patient outcomes. High expression of these SLC30 members generally correlates with improved survival rates in untreated patients. However, these same transporters serve as negative prognostic markers for patients undergoing tamoxifen treatment. Additionally, this suggests that zinc-mediated signaling might contribute to acquired endocrine resistance in clinical settings.

Furthermore, researchers identified that zinc-dependent inhibition of phosphatases directly influences kinase signaling cascades. Therefore, these transporters offer promising novel targets for therapeutic intervention in resistant breast cancer cases. In addition, the findings position the SLC30 family as active participants in signaling rather than just simple ion exporters.

How do SLC30 transporters affect breast cancer cell growth?

They regulate the PTP/AKT/ESR1 pathway by modulating zinc levels. This process inhibits certain phosphatases and activates kinase signaling to promote proliferation without needing estrogen.

Why does SLC30 expression represent a prognostic paradox?

High SLC30 levels correlate with better survival generally, but they predict poor outcomes for patients treated with tamoxifen, potentially indicating drug resistance.

Disclaimer: This content is for informational and educational purposes only. It does not constitute medical advice or substitute for professional judgment. Refer to the latest local and national guidelines for clinical practice.

References

Lekki-Porębski S et al. SLC30A1, SLC30A5 and SLC30A9 transporters play crucial role in ligand-independent activation of ESR1 signalling in breast cancer cells via modulation of AKT activity by zinc. Metallomics. 2026 Mar 06. doi: undefined. PMID: 41790496.

Taylor KM et al. ZIP7-mediated intracellular zinc transport contributes to aberrant growth factor signaling in antihormone-resistant breast cancer cells. Endocrinology. 2008 Oct;149(10):4912-20. doi: 10.1210/en.2008-0351.

Liu J et al. Systematic characterization of zinc in a series of breast cancer cell lines reveals significant changes in zinc homeostasis. J Biol Chem. 2025 Jul;301(8):110442. doi: 10.1016/j.jbc.2025.110442.