Ceramide-induced Endoplasmic Reticulum Stress as a Targetable Vulnerability in Endocrine Therapy-Resistant Breast Cancer

Pal, P.; Chitkara, S.; Sarpey, G. K.; Alani, F.; Zhao, H.; Ata, M.; Qu, J.; Schiff, R.; Tonetti, D.; Greene, G. L.; Frasor, J.; Atilla, G. E.; Coloff, J. L.

doi:10.1101/2025.08.18.670862

bioRxiv · 10.1101/2025.08.18.670862

Ceramide-induced Endoplasmic Reticulum Stress as a Targetable Vulnerability in Endocrine Therapy-Resistant Breast Cancer

Pal, P.·Chitkara, S.·Sarpey, G. K.·Alani, F.·Zhao, H.·Ata, M.·Qu, J.·Schiff, R.·Tonetti, D.·Greene, G. L.·Frasor, J.·Atilla, G. E.·Coloff, J. L.

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Abstract

Despite the success of endocrine therapy (ET) in treating hormone receptor-positive breast cancer, a significant proportion of patients relapse during or after treatment, making ET resistance a major clinical challenge. Previously we have shown that ET-resistant breast cancer cells exhibit reduced ceramide levels and an increased sensitivity to ceramide-induced cell death. Here, we demonstrate that ceramides induce a distinct transcriptional reprogramming in ET-resistant cells, characterized by upregulation of endoplasmic reticulum stress (EnRS) pathways. Ceramide-induced EnRS is PERK-dependent and functionally linked to cell death in multiple models of ET resistance. Using a photoactivatable ceramide probe, we identify TRAM1 as a functionally important ceramide-interacting protein (CIP) in ET-resistant cells that correlates with worse relapse-free survival and a more aggressive breast cancer phenotype in luminal breast cancer patients. Additionally, knockdown of TRAM1 phenocopies ceramide action in ET resistance, thereby suggesting its role in mediating ceramide-induced lethal actions in ET resistance. Together, our findings reveal that ET-resistant breast cancer cells are more sensitive to PERK-mediated EnRS as compared to their ET-sensitive counterparts. Ceramides can exploit this dependence by interacting with CIPs such as TRAM1, leading to PERK activation and consequential cell death preferentially in the ET-resistant breast cancer models.

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Pal, P., Chitkara, S., Sarpey, G. K., Alani, F., Zhao, H., Ata, M., Qu, J., Schiff, R., Tonetti, D., Greene, G. L., Frasor, J., Atilla, G. E., Coloff, J. L.. 2025-08-22. Ceramide-induced Endoplasmic Reticulum Stress as a Targetable Vulnerability in Endocrine Therapy-Resistant Breast Cancer. https://doi.org/10.1101/2025.08.18.670862

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