X-linked cancer-associated polypeptide (XCP) from lncRNA1456 modulates PHF8 histone demethylase activity to regulate the epigenome, gene expression, and cellular pathways in breast cancer

Authors

• Shrikanth S. Gadad, The University of Texas Rio Grande ValleyFollow
• Cristel V. Camacho, University of Texas Southwestern Medical Center
• Xuan Gong, University of Texas Southwestern Medical Center
• Micah Thornton, University of Texas Southwestern Medical Center
• Venkat S. Malladi, University of Texas Southwestern Medical Center
• Anusha Nagari, University of Texas Southwestern Medical Center
• Aishwarya Sundaresan, University of Texas Southwestern Medical Center
• Tulip Nandu, University of Texas Southwestern Medical Center
• Sneh Koul, University of Texas Southwestern Medical Center
• Yan Peng, University of Texas Southwestern Medical Center
• W. Lee Kraus

Document Type

Article

Publication Date

4-1-2026

Abstract

Recent studies have demonstrated that a subset of long “noncoding” RNAs (lncRNAs) produce functional polypeptides and proteins. In this study, we discovered a 132 amino acid protein in human breast cancer cells named XCP (X-linked Cancer-associated Polypeptide), which is encoded by lncRNA1456 (a.k.a. RHOXF1P3), a transcript previously thought to be noncoding. lncRNA1456 is a pancreas- and testis-specific RNA whose gene is located on chromosome X. We found that the expression of lncRNA1456 and XCP is highly upregulated in the luminal A, luminal B, and HER2 molecular subtypes of breast cancer. XCP modulates both estrogen-dependent and estrogen-independent growth of breast cancer cells by regulating cancer pathways, as shown in cell and xenograft models. XCP shares some homology with homeodomain-containing proteins and interacts with the histone demethylase plant homeodomain finger protein 8 (PHF8), which is also encoded by an X-linked gene. Mechanistically, XCP is required for the binding of PHF8 to chromatin. Moreover, XCP stimulates the histone demethylase activity of PHF8 to regulate gene expression in breast cancer cells. These findings identify XCP as a coregulator of PHF8 in the chromatin-dependent regulation of gene expression and emphasize the need to interrogate the potential functional roles of open reading frames originating from noncoding RNAs.

Comments

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Recommended Citation

Gadad, S. S., Camacho, C. V., Gong, X., Thornton, M., Malladi, V. S., Nagari, A., Sundaresan, A., Nandu, T., Koul, S., Peng, Y., & Kraus, W. L. (2026). X-linked cancer-associated polypeptide (XCP) from lncRNA1456 modulates PHF8 histone demethylase activity to regulate the epigenome, gene expression, and cellular pathways in breast cancer. Oncogene, 45(17), 1557–1571. https://doi.org/10.1038/s41388-026-03740-w

Creative Commons License

This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.

Publication Title

Oncogene

DOI

10.1038/s41388-026-03740-w

Academic Level

faculty

Mentor/PI Department

Immunology and Microbiology