Estrogen maintains myometrial tumors in a lymphangioleiomyomatosis model

Abstract

Lymphangioleiomyomatosis (LAM) is a rare disease in women. Patients with LAM develop metastatic smooth-muscle cell adenomas within the lungs, resulting in reduced pulmonary function. LAM cells contain mutations in tuberous sclerosis genes (TSC1 or TSC2), leading to up-regulation of mTORC1 activity and elevated proliferation. The origin of LAM cells remains unknown; however, inactivation of Tsc2 gene in the mouse uterus resulted in myometrial tumors exhibiting LAM features, and approximately 50% of animals developed metastatic myometrial lung tumors. This suggests that LAM tumors might originate from the uterine myometrium, possibly explaining the overwhelming prevalence of LAM in female. Here, we demonstrate that mouse Tsc2-null myometrial tumors exhibit nearly all the features of LAM, including mTORC1/S6K activation, as well as expression of melanocytic markers and matrix metalloproteinases (MMPs). Estrogen ablation reduces S6K signaling and results in Tsc2-null myometrial tumor regression. Thus, even without TSC2, estradiol is required to maintain tumors and mTORC1/S6K signaling. Additionally, we find that MMP-2 and −9, as well as neutrophil elastase (NE), are overexpressed in Tsc2-null myometrial tumors in an estrogen-dependent fashion. In vivo fluorescent imaging using MMP- or NE-sensitive optical biomarkers confirms that protease activity is specific to myometrial tumors. Similar to LAM cells, uterine Tsc2-null myometrial cells also overexpress melanocytic markers in an estrogen-dependent fashion. Finally, we identify glycoprotein NMB (GPNMB) as a melanocytic marker up-regulated in Tsc2-null mouse uteri and human LAM samples. Our data highlight the potential importance of estradiol in LAM cells, suggesting that anti-estrogen therapy may be a treatment modality. Furthermore, proteases and GPNMB might be useful LAM biomarkers.

Infiltrating Myeloid Cells Exert Protumorigenic Actions via Neutrophil Elastase

“…Cells were lysed in RIPA (Pierce) supplemented with 1× Halt protease and phosphatase inhibitor cocktail (Thermo Scientific). Samples were processed for gel electrophoresis and Western blotted with rabbit anti-phospho-Erk1/2 (1:1000, catalog#9101, Cell Signaling) and rabbit anti-total-Erk1/2 (1:1000, catalog#9102, Cell Signaling) as previously described (35). Band densitometry was performed using ImageJ v1.48 software.…”

Glycoprotein Non-Metastatic Melanoma Protein B (GPNMB) and Cancer: A Novel Potential Therapeutic Target

“…This study demonstrated positive GPNMB staining in LAM-like tumor cells in the lymph nodes and uterus, as well as uniform staining within LAM nodules and the walls of lung cysts in lung LAM from five different patient samples [7]. …”

“…However, successive transcriptional profiling and tumor microarray studies in primary melanoma and breast cancers established GPNMB as an aggressive pro-metastatic protein [4–6]. GPNMB is now known to be highly expressed in multiple tumor types, including triple negative breast cancers (TNBC), uveal and cutaneous melanoma, glioblastomas, hepatocellular carcinoma, prostate cancer, osteosarcoma, lung cancer, bladder cancer, and lymphangioleiomyomatosis (LAM) [7–11], making it a critical protein in tumor biology and an attractive target for therapeutic interventions.…”

Lymphangioleiomyomatosis

“…19,20 Importantly, estrogen receptors and progesterone receptors play important roles in LAM development and progression. [21][22][23][24] In the past, antiestrogen therapies were used in the treatment of LAM without clear evidence of benefit. 25…”