Abstract P3-03-27: Klotho proteins and small non-coding RNAs as potential prognostic markers and therapeutic targets for human triple-negative breast cancer and canine mammary carcinoma

Abstract Background: In addition to humans, dogs are one of the few animal species that also develop breast cancer, referred to as canine mammary carcinoma (CMC). CMC is the most prevalent tumor detected in intact female dogs. In contrast to laboratory rodents, CMC develops spontaneously and doesn’t require genetic engineering or xenograft models. Furthermore, at a cellular level, mammary carcinoma in dogs is very similar to human breast cancer tumors. The high mortality rates of human breast cancer and CMC, along with the limited treatment options for aggressive triple-negative breast cancer (TNBC), highlight the urgent need for early diagnostic markers and new therapeutic targets for these diseases. A family of proteins involved in metabolism and aging, called Klotho, has been found to have an important role in carcinogenesis. αKlotho and βKlotho proteins act like tumor suppressors and are repressed by microRNAs (miRNAs) during oncogenesis. However, the role of γKlotho in cancer remains to be fully elucidated. Our previous studies suggest that γKlotho is activated in TNBC and acts as an oncogene. However, the molecular underpinning of its functions, expression regulation, and expression in CMC is not known. Here we aimed to determine the expression of γKlotho in TNBC and CMC, and its correlation with miRNA signature to understand its function and regulation in both species. Methods: RNA and miRNA were isolated from tumors and benign mammary tissues from female dogs (n=31) and two CMC cell lines (CF41.Mg and CMT U27) and subjected to mRNA and miRNA expression quantification using RT-qPCR, RNA, and microRNA sequencing. Results: Our data suggest that similarly to TNBC, the mRNA expression of γKlotho is significantly upregulated in CMC compared to normal mammary gland (μ = 0.007 ±0.0007 AU, min=0, max=0.045) compared to normal tissue (μ = 0.0003±0.0003 AU, min=0, max=0.0007), suggesting a role of γKlotho in the oncogenesis of both aggressive diseases. Conclusions and future work: γKlotho may represent promising novel therapeutic targets or stratifying markers for aggressive CMC and TNBC. Female dogs may represent a great preclinical model for potential therapeutic interventions of γKlotho-positive tumors, holding the potential to improve the therapeutic alternatives for both human and canine patients. Further analyses are underway to understand the molecular mechanisms of regulation by miRNA and molecular action. Citation Format: Luciana Mayer Kluppel, Klementina Fon Tacer, Fernanda Rosa, Tanja Plavec, Tana Srava, Vladimira Erjavec, Joseph Emmons, Heather Tilman, Alicia K. Olivier, Danijela Herga. Klotho proteins and small non-coding RNAs as potential prognostic markers and therapeutic targets for human triple-negative breast cancer and canine mammary carcinoma [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2024; 2024 Dec 10-13; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(12 Suppl):Abstract nr P3-03-27.