<p>(A) Box plots of phosphoAKT1 or MYC levels in low- or high-Gleason prostate tumors. (B) Representative cases of phosphoAKT1-high/MYC-low (orange box), phosphoAKT1-high/MYC-high (dark grey box), phosphoAKT1-low/MYC-high (green box) and phosphoAKT1-low/MYC-low (light grey box) prostate tumors and matched normal samples are shown with immunoblots for phosphoAKT1 and MYC. (C) Schematic illustration of the methodology.</p>
<p>Segregation of phosphoAKT1-high and MYC-high prostate tumors by genomics and protein expression. (A) SNP arrays (Affymetrix 250K Sty I array) were performed on 59 prostate tumors and 6 normal tissues. The heat map showing inferred copy number profile was generated with DChip version 2010.01. Densitometric values of phosphoAKT1 or MYC protein (relative to β-actin) for each sample are depicted in the top orange/green heat map. The black bars in the color scales represent the cut-off for low and high protein values. (B) Venn diagram showing the intersections between genomic and protein expression data. Twelve and 11 tumors harbored 10q23.31 loss (PTEN locus, orange circle in (A), chromosome 10) and 8q24.3 gain (MYC locus, green circle in (A), chromosome 8), respectively, representing 26% (7/27) of phosphoAKT1-high and 13% (2/15) of MYC-high tumors.</p>
Lymphangioleiomyomatosis (LAM) is a multisystem disease occurring in women of child-bearing age manifested by uncontrolled proliferation of smooth muscle-like "LAM" cells in the lungs. LAM cells bear loss-of-function mutations in tuberous sclerosis complex (TSC) genes TSC1 and/or TSC2, causing hyperactivation of the proliferation promoting mammalian/mechanistic target of Rapamycin complex 1 pathway. Additionally, LAM-specific active renin-angiotensin system (RAS) has been identified in LAM nodules, suggesting this system potentially contributes to neoplastic properties of LAM cells; however, the role of this renin-angiotensin signaling is unclear. Here, we report that TSC2-deficient cells are sensitive to the blockade of angiotensin II receptor type 1 (Agtr1). We show that treatment of these cells with the AGTR1 inhibitor losartan or silencing of the Agtr1 gene leads to increased cell death in vitro and attenuates tumor progression in vivo. Notably, we found the effect of Agtr1 blockade is specific to TSC2-deficient cells. Mechanistically, we demonstrate that cell death induced by Agtr1 inhibition is mediated by an increased expression of Klotho. In TSC2-deficient cells, we showed overexpression of Klotho or treatment with recombinant (soluble) Klotho mirrored the cytocidal effect of angiotensin blockade. Furthermore, Klotho treatment decreased the phosphorylation of AKT, potentially leading to this cytocidal effect. Conversely, silencing of Klotho rescued TSC2-deficient cells from cell death induced by Agtr1 inhibition. Therefore, we conclude that Agtr1 and Klotho are important for TSC2-deficient cell survival. These findings further illuminate the role of the RAS in LAM and the potential of targeting Agtr1 inhibition in TSC2-deficient cells.
Significance The mechanisms of chromophobe renal cell carcinoma (ChRCC) pathogenesis remain a key knowledge gap. Through metabolomics, this study uncovered a fundamental metabolic mechanism underlying the pathogenesis of ChRCC, with key therapeutic implications for this rare tumor type, for which there are currently no specific targeted therapies. Further understanding of the impact of glutathione salvage pathway on mitochondrial function, tumor progression, and targeted therapy can provide insight into other cancers characterized by aberrant glutathione salvage pathway.
Abstract Sarcoma represents a class of tumors arising from mesenchymal tissue. New approaches that target sarcoma-specific molecular alterations hold a promise of more effective therapies. Currently available sarcoma models do not accurately resemble relevant properties of the human disease and very often are inadequate for predicting the efficacy of investigational drugs in preclinical settings. Thus, in order to test novel targeted therapies, it is essential to develop in vivo models of sarcomas. To this end, we have created a panel of well-characterized xenografts of primary human sarcomas that represent a spectrum of histotypes. Specifically, we transplanted intact human sarcomas under the skin of immunodeficient mice. We then compared the morphologic, phenotypic, and genetic characteristics of the tumor tissues before and after implantation in recipient mice. To date, we have implanted into Nu/Nu recipients tumor tissue fragments from 32 gastrointestinal stromal tumors (GIST) 10 dedifferentiated liposarcomas and 6 leiomyosarcomas. Successful tumor growth was detected in 86% cases of GIST, 44% of liposarcomas and 33% of leiomyosarcomas. Upon serial transplantation, 35% of GISTs, 44% of liposarcomas and 33% of leiomyosarcomas have grown beyond passage F3. Histological analysis of the primary tumors and corresponding xenografts revealed that morphology and immunophenotype (c-Kit status for GISTs, MDM2 for liposarcomas, Smooth Muscle Actin for leiomyosarcomas) was retained throughout all passages. Moreover, all major genetic abnormalities present in the primary tumors were retained in the xenografts, as revealed by genome-wide Single Nucleotide Polymorphism (SNP) array analyses. Our results show that this approach can be used to generate animal models that faithfully reproduce characteristics of human intact tumors. These models can be used for in vivo preclinical drug testing, diagnostic and prognostic molecular markers discovery, and for identification of molecular mechanisms of drug resistance. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4197.
