Abstract 1316: Tamm-Horsfall protein as a novel antitumor therapy for triple negative breast cancer
Authors: Mercogliano María Florencia , Bruni Sofia , De Martino Mara , Cavanagh Elena , Balanian Liliana , Sojo Emilio , Inserra Felipe , Groisman Jose , Schillaci Roxana 
Published: June 2022

Tamm-Horsfall Protein (THP) is expressed exclusively in the kidney and is the most abundant protein in urine. THP has a role in antibacterial host defense but also in inflammatory disorders of the urogenital tract. THP has been shown to regulate the innate and adaptive immunity in the urinary tract by potently activating macrophages and dendritic cells. Given these immunostimulatory effects, we hypothesize that systemic THP administration can promote an antitumor and antimetastatic response. THP was isolated from human urine of healthy individuals at a purity of &gt;99% with less than &lt; 1 UE/mg de THP of endotoxin. We treated murine J744 macrophages and human monocytes with 10 and 100 µg/ml THP for 18h and TNFα levels were determined by ELISA. In J744 macrophages TNFα levels reached 0.9 and 1.4 ng/ml, respectively and in human monocytes 4.5 and 6 ng/ml, respectively, confirming the macrophage-stimulating properties of THP. We then evaluated proliferation and migration by cell count and wound healing, respectively, in the 4T1 murine triple negative breast cancer (TNBC) model and the MDA-MB-231 human TNBC model. We cultured 4T1 and MDA-MB-231 cells for 4 days with 100 µg/ml THP and observed an inhibition in proliferation of 62% and 40%, respectively. Cell migration was evaluated under treatment with 100 µg/ml THP for 18h. Migration was inhibited by 70% in 4T1 cells and by 30% in MDA-MB-231 cells. These data highlight the antitumoral and antimetastatic effect of THP in TNBC. The in vivo experiments were performed by administering THP 3 times a week and/or docetaxel (Dx) at 15 mg/kg twice a week in BALB/c mice bearing 4T1 tumors (50-75 mm2), and tumor growth, lung metastasis and survival were determined. A dose-response curve (0.3-3 mg/kg) was performed using THP administered either s.c. or i.p. THP s.c. at 1.5 µg/kg and THP i.p. at 3 µg/kg induced 40% and 38% tumor growth inhibition, respectively. THP also reduced metastasis measured as the number of lung nodules, and the addition of Dx deepened the effect even more. In the case of survival studies, the tumors were surgically removed after reaching 50 mm3 and two days later the animals were treated with vehicle, Dx, or Dx+THP. Log rank analysis of Kaplan-Meier plots showed a significant improvement of overall survival in mice treated with Dx+THP (P= 0.011) and only a trend with Dx treatment (P=0.067). Here we show that THP decreases TNBC proliferation, reduces metastasis dissemination and improves Dx's effect. These evidences are especially important in TNBC whose standard of care is only chemotherapy. In conclusion, THP can be a valuable agent to enhance the use of Dx in the chemotherapy treatment of TNBC tumors. However, beneficial effects over other tumors should be confirmed.

Citation Format: María Florencia Mercogliano, Sofia Bruni, Mara De Martino, Elena Cavanagh, Liliana Balanian, Emilio Sojo, Felipe Inserra, Jose Groisman, Roxana Schillaci. Tamm-Horsfall protein as a novel antitumor therapy for triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1316.