In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.

[EX Q]: Context: High arginase-1 (Arg) expression by myeloid-derived suppressor cells (MDSC) is known to inhibit antitumor T-cell responses through depletion of l-arginine. We have previously shown that nitric oxide (NO), an immune mediator produced from l-arginine, is a potent radiosensitizer of hypoxic tumor cells. This study therefore examines whether Arg(+) overexpressing MDSC may confer radioresistance through depleting the substrate for NO synthesis.', 'MDSC and Arg expression were studied in preclinical mouse CT26 and 4T1 tumor models and further validated in rectal cancer patients in comparison with healthy donors. The radioprotective effect of MDSC was analyzed in hypoxic tumor cells with regard to l-arginine depletion.', 'In both mouse tumors and cancer patients, MDSC expansion was associated with Arg activation causing accelerated l-arginine consumption. l-Arginine depletion in turn profoundly suppressed the capacity of classically activated macrophages to synthesize NO resulting in impaired tumor cell radiosensitivity. In advanced cT3-4 rectal cancer, circulating neutrophils revealed Arg overexpression approaching that in MDSC, therefore mounting a protumor compartment wherein Arg(+) neutrophils increased from 17% to over 90%.\Question: Do myeloid-derived suppressor cells reveal radioprotective properties through arginase-induced l-arginine depletion?
[EX A]: Protumor Arg(+) MDSC reveal a unique ability to radioprotect tumor cells through l-arginine depletion, a common mechanism behind both T-cell and macrophage inhibition.

[EX Q]: Context: Characteristic clinical heterogeneity and mostly slow-growing behavior of gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) cause problems in finding appropriate treatments. Thus, current therapy options are not satisfactory. PKI-587 is a highly potent novel dual inhibitor of PI3K and mTORC1/C2.', 'We assessed the effects of PKI-587 in different GEP-NEN tumor models, including poorly differentiated cell line LCC-18, compared with the established mTORC1 inhibitor everolimus.', 'We treated the cell lines BON, QGP1, KRJ-I and LCC-18 with increasing concentrations of the inhibitor PKI-587, and compared with everolimus and DMSO. We assessed the impact of treatments on viability (WST-1 assay), on apoptotic processes (Caspase 3/7 assay, JC-1) and on cell cycle regulation (flow cytometry). We determined alterations of signaling mediators by phosphor-specific western blot analysis and conducted multiplexed gene expression analysis (nCounter®️ technology).', 'In all cell lines, PKI-587 dose-dependently inhibited proliferation whereas everolimus was less effective. Treatment with PKI-587 led to cell cycle arrest, induction of apoptosis and successfully suppressed activity of direct mTORC1 target 4E-BP1, a crucial factor for tumor genesis only partially inhibited by everolimus. Gene expression analyses revealed relevant changes of RAS, MAPK, STAT and PI3K pathway genes after treatment. Treatment dependent and cell line characteristic effects on AKT/RB/E2F signaling regarding cell cycle control and apoptosis are extensively discussed in this article.\Question: Is inhibition of mTORs Catalytic Site by PKI-587 a Promising Therapeutic Option for Gastroenteropancreatic Neuroendocrine Tumor Disease?
[EX A]: PI3K/mTOR dual targeting is a promising new therapeutic approach in neuroendocrine tumor disease that should be evaluated in further clinical trials.

[EX Q]: Context: Pituitary tumor-transforming gene (PTTG) is a multifunctional protein involved in several tumorigenic mechanisms, including angiogenesis. PTTG has been shown to promote angiogenesis, a key rate-limiting step in tumor progression, by up-regulation of fibroblast growth factor-2 and vascular endothelial growth factor.', 'To investigate whether PTTG regulates other angiogenic genes in thyroid cells, we performed angiogenesis-specific cDNA arrays after PTTG transfection. Two of the genes [inhibitor of DNA binding-3 (ID3) and thrombospondin-1 (TSP-1)] which showed differential expression in primary thyroid cells were validated in vitro and in vivo.', 'TSP-1 showed a 2.5-fold reduction and ID3 showed a 3.5-fold induction in expression in response to PTTG overexpression in vitro. Conversely, suppression of PTTG with small interfering RNA was associated with a 2-fold induction of TSP-1 and a 2.2-fold reduction in ID3 expression. When we examined TSP-1 and ID3 expression in 34 differentiated thyroid cancers, ID3 was significantly increased in tumors compared with normal thyroid tissue. Furthermore, ID3 expression was significantly higher in follicular thyroid tumors than in papillary tumors. Although mean TSP-1 expression was not altered in cancers compared with normal thyroids, we observed a significant independent association between TSP-1 expression and early tumor recurrence, with recurrent tumors demonstrating 4.2-fold lower TSP-1 expression than normal thyroid tissues.\Question: Does pituitary tumor-transforming gene regulate multiple downstream angiogenic genes in thyroid cancer?
[EX A]:
We have identified ID3 and TSP-1 as two new downstream targets of PTTG in thyroid cancer. We propose that PTTG may promote angiogenesis by regulating the expression of multiple genes with both pro- and antiangiogenic properties and may thus be a key gene in triggering the angiogenic switch in thyroid tumorigenesis.