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Supplementary Table S1 from Loss of Nuclear Localized Parathyroid Hormone-Related Protein in Primary Breast Cancer Predicts Poor Clinical Outcome and Correlates with Suppressed Stat5 Signaling

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posted on 2023-03-31, 20:49 authored by Thai H. Tran, Fransiscus E. Utama, Takahiro Sato, Amy R. Peck, John F. Langenheim, Sameer S. Udhane, Yunguang Sun, Chengbao Liu, Melanie A. Girondo, Albert J. Kovatich, Jeffrey A. Hooke, Craig D. Shriver, Hai Hu, Juan P. Palazzo, Marluce Bibbo, Paul W. Auer, Michael J. Flister, Terry Hyslop, Edith P. Mitchell, Inna Chervoneva, Hallgeir Rui

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Susan G. Komen for the Cure

National Institutes of Health

Worldwide Cancer Research

Medical College of Wisconsin Cancer Center Institutional Research

Swiss National Science Foundation

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ARTICLE ABSTRACT

Parathyroid hormone-related protein (PTHrP) is required for normal mammary gland development and biology. A PTHLH gene polymorphism is associated with breast cancer risk, and PTHrP promotes growth of osteolytic breast cancer bone metastases. Accordingly, current dogma holds that PTHrP is upregulated in malignant primary breast tumors, but solid evidence for this assumption is missing. We used quantitative IHC to measure PTHrP in normal and malignant breast epithelia, and correlated PTHrP levels in primary breast cancer with clinical outcome. PTHrP levels were markedly downregulated in malignant compared with normal breast epithelia. Moreover, low levels of nuclear localized PTHrP in cancer cells correlated with unfavorable clinical outcome in a test and a validation cohort of breast cancer treated at different institutions totaling nearly 800 cases. PTHrP mRNA levels in tumors of a third cohort of 737 patients corroborated this association, also after multivariable adjustment for standard clinicopathologic parameters. Breast cancer PTHrP levels correlated strongly with transcription factors Stat5a/b, which are established markers of favorable prognosis and key mediators of prolactin signaling. Prolactin stimulated PTHrP transcript and protein in breast cancer cell lines in vitro and in vivo, effects mediated by Stat5 through the P2 gene promoter, producing transcript AT6 encoding the PTHrP 1-173 isoform. Low levels of AT6, but not two alternative transcripts, correlated with poor clinical outcome. This study overturns the prevailing view that PTHrP is upregulated in primary breast cancers and identifies a direct prolactin–Stat5–PTHrP axis that is progressively lost in more aggressive tumors.

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