THU483 Role Of Excess GH On Breast Cancer Aggressiveness And Metastasis In Acromegaly

Disclosure: J. Oh: None. C. Kang: None. E. Wang: None. S. Lee: None. J. Nam: None. C. Ku: None. E. Lee: None. Introduction Acromegaly is a rare disease characterized by chronic growth hormone (GH) and insulin-like growth factor-1 hypersecretion. In previous studies, it is known that the incidence of breast cancer increases in patients with acromegaly. For breast cancers, autocrine GH and GHR are expressed in primary lesion, which is significantly increased in metastatic one. To date, however, the precise mechanism of endocrine GH in breast cancer metastasis has not been defined. This study aimed to investigate the role of endocrine excess GH facilitating breast cancer metastasis in acromegaly mice model. Method We used Aip(lox/lox) (Con) and rGHp-Cre(tg/+); Aip(lox/lox) mice (Acro), which was previously established to model the phenotype of human acromegaly. To generate orthotopic xenograft model, we used C57BL/6 female mouse derived breast cancer cell line Py230 cells. Py230 cells were injected into mammary gland and tumor volumes were measured every 2 days. Tumor growth and metastasis were confirmed by bioluminescent in vivo imaging system (IVIS). Also, we investigated the effects of GH on triple negative breast cancer cell lines, which have the higher expression of GHR. To define GH induced pathway, we performed RT(2) array. Cell proliferation was investigated with MTT assay and cell migration was investigated with wound healing assay and transwell invasion assay. Results In mouse orthotopic xenograft studies, tumor volumes of Acro mice were higher than that of Con mice (increase of 310%, 846.04±290.7 vs. 205.97±33.7 mm(3), p=0.001). The tumor volume and serum GH level showed positive correlation (R(2)= 0.4739, p=0.027). After 14 weeks, the Acro mice showed significantly increased bioluminescence activity in the lung (increase of 1023%, 494666.7±104668.2 vs. 44037.7±6641.9 AU, p=0.0127). When GHR antagonist was treated, tumor growth and lung metastasis were decreased. We excised primary tumor and lung metastatic foci and performed RT(2) array. We found Tcf-20 gene, which is upregulated in both primary tumor and lung metastatic burden (increase of 216%, p=0.0153). We confirmed GH induced Tcf-20 gene induction (increase of 57% (p=0.043), 41% (p=0.05), 67% (p=0.0021) in Hs578T, Py230 (p=0.05), and Hcc1806 cells each). We knocked down Ghr or Tcf-20 genes and observed decrease of invasion and migration compared to GH treated siCON HCC1806 (decrease of 64.5% in siGHR, decrease of 83.3% in siTCF-20, compared to siCON cells, p=0.000819977) and Py230 cells (decrease of 47.3% in siGHR transfected, decrese of 49.3% in siTCF-20 transfected, compared to siCON cells, p=0.0012). Conclusion Excess GH in acromegaly possess a strong potential to promotes tumor development and metastasis. We identified a molecular mechanism by which GH-induced TCF-20 promote tumor aggression and metastasis. These findings can aid in the development of improved strategies for managing cancer in acromegalic patients. Presentation: Thursday, June 15, 2023