The rapamycin-derivative RAD001 (everolimus) inhibits cell viability and interacts with the Akt–mTOR–p70S6K pathway in human medullary thyroid carcinoma cells

Grozinsky‐Glasberg, Simona; Rubinfeld, Hadara; Nordenberg, Yardena; Gorshtein, Alexander; Praiss, Michal; Kendler, Efrat; Feinmesser, R; Grossman, Ashley; Shimon, Ilan

doi:10.1016/j.mce.2009.09.027

Cited by 34 publications

(27 citation statements)

References 37 publications

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“…Furthermore, our data show that inhibition of mTOR pathway causes significant reduction of MTC cell proliferation, motility, and tumorigenicity. Rad001 effects on TT cell proliferation were consistent with those recently reported (22).…”

Section: Discussionsupporting

confidence: 91%

Activation of the mTOR Pathway in Primary Medullary Thyroid Carcinoma and Lymph Node Metastases

Tamburrino

Molinolo

Salerno

et al. 2012

Clinical Cancer Research

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Purpose: Understanding the molecular pathogenesis of medullary thyroid carcinoma (MTC) is prerequisite to the design of targeted therapies for patients with advanced disease.Experimental Design: We studied by immunohistochemistry the phosphorylation status of proteins of the RAS/MEK/ERK and PI3K/AKT/mTOR pathways in 53 MTC tissues (18 hereditary, 35 sporadic), including 51 primary MTCs and 2 cases with only lymph node metastases (LNM). We also studied 21 autologous LNMs, matched to 21 primary MTCs. Staining was graded on a 0 to 4 scale (S score) based on the percentage of positive cells. We also studied the functional relevance of the mTOR pathway by measuring cell viability, motility, and tumorigenicity upon mTOR chemical blockade.Results: Phosphorylation of ribosomal protein S6 (pS6), a downstream target of mTOR, was evident (S ! 1) in 49 (96%) of 51 primary MTC samples. This was associated with activation of AKT (phosphoSer473, S > 1) in 79% of cases studied. Activation of pS6 was also observed (S ! 1) in 7 (70%) of 10 hereditary C-cell hyperplasia specimens, possibly representing an early stage of C-cell transformation. It is noteworthy that 22 (96%) of 23 LNMs had a high pS6 positivity (S ! 3), which was increased compared with autologous matched primary MTCs (P ¼ 0.024). Chemical mTOR blockade blunted viability (P < 0.01), motility (P < 0.01), and tumorigenicity (P < 0.01) of human MTC cells.Conclusion: The AKT/mTOR pathway is activated in MTC, particularly, in LNMs. This pathway sustains malignant features of MTC cell models. These findings suggest that targeting mTOR might be efficacious in patients with advanced MTC. Clin Cancer Res; 18(13); 3532-40. Ó2012 AACR.

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Section: Discussionsupporting

confidence: 91%

Activation of the mTOR Pathway in Primary Medullary Thyroid Carcinoma and Lymph Node Metastases

Tamburrino

Molinolo

Salerno

et al. 2012

Clinical Cancer Research

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“…It has been proposed that PTEN may also play a role inside the nucleus, where it regulates chromosomal integrity, cell cycle progression, p53 acetylation, and DNA-damage response through the interaction with RAD51 as well as in apoptosis induction (20). Putting our results together it seems that the mechanisms of action of PTEN may be twofold: on one hand the decrease in PTEN cytoplasmic expression can lead to a higher mTOR activity, and on the other hand, the high nuclear PTEN expression observed in some of our cases can also influence other cellular processes and putatively contribute to It has been demonstrated that MTC cancer cell lines are sensitive to mTOR inhibitors (3,4,13,21). It was also observed, in melanoma (22,23), that sensitivity to an mTOR inhibitor was correlated with pre-treatment p-S6 levels, but not with other downstream effectors of this pathway (PI3K and p-AKT) (22,23).…”

Section: Discussionsupporting

confidence: 52%

“…MTC is thought to be responsible for up to 14% of all thyroid cancerrelated deaths, distant metastases being the main cause in this setting (2). Treatment of patients with MTC is still difficult in many cases and alternative therapeutic options have been proposed (2,3,4,5).…”

Section: Introductionmentioning

confidence: 99%

mTOR activation in medullary thyroid carcinoma with RAS mutation

Lyra

Vinagre

Batısta

et al. 2014

European Journal of Endocrinology

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Objective: Rearranged during transfection (RET) mutations are well-known genetic events in sporadic and familial medullary thyroid carcinoma (FMTC). The presence of RAS mutations in sporadic cases, challenging the RET paradigm in these tumors, has been recently reported. We intend to evaluate mTOR pathway activation in RET-and RAS-mutated MTC. Materials and methods: In this study, we analysed the presence of RET, H-RAS, and K-RAS mutations in a series of 87 MTCs (82 apparently sporadic and five FMTCs; five apparently sporadic MTCs were eventually found to be familial). We also evaluated mTOR activation -using the expression of its downstream effector phospho-S6 ribosomal protein (p-S6) and the expression of the mTOR inhibitor, phosphatase and tensin homologue deleted on chromosome 10 (PTEN) -by immunohistochemistry. Results: Our results revealed that RET mutations were present in 52.9% of the cases (46/87) and RAS mutations in 12.6% (11/87) of the whole series of MTCs and 14.3% of the 77 sporadic MTCs. The presence of RET and RAS mutations was mutually exclusive. RAS mutations were significantly associated with higher intensity of p-S6 expression (PZ0.007), suggesting that the mTOR pathway is activated in such MTCs. We observed also an increased expression of p-S6 in invasive tumors (PZ0.042) and in MTCs with lymph node metastases (PZ0.046). Cytoplasmic PTEN expression was detected in 58.8% of the cases; cases WT for RAS showed a significantly lower expression of PTEN (PZ0.045). Conclusions: We confirmed the presence of RAS mutation in 14.3% of sporadic MTCs and report, for the first time, an association between such mutations and the activation of the mTOR pathway. The evaluation of the mTOR activation by pS6 expression may serve as an indicator of invasive MTC.

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“…Recent studies demonstrated that the presence of the RET mutation is also associated with activation of the mammalian target of rapamycin (mTOR) signaling in MTC cells (Grozinsky-Glasberg et al 2010, Faggiano et al 2011.…”

Section: Introductionmentioning

confidence: 99%

Metformin inhibits growth and decreases resistance to anoikis in medullary thyroid cancer cells

Kłubo-Gwieździńska

Jensen²,

Costello³

et al. 2012

Endocrine-Related Cancer

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Medullary thyroid cancer (MTC) is associated with activation of mammalian target of rapamycin (mTOR) signaling pathways. Recent studies showed that the antidiabetic agent metformin decreases proliferation of cancer cells through 5 0 -AMP-activated protein kinase (AMPK)-dependent inhibition of mTOR. In the current study, we assessed the effect of metformin on MTC cells. For this purpose, we determined growth, viability, migration, and resistance to anoikis assays using two MTC-derived cell lines (TT and MZ-CRC-1). Expressions of molecular targets of metformin were examined in MTC cell lines and in 14 human MTC tissue samples. We found that metformin inhibited growth and decreased expression of cyclin D1 in MTC cells. Treatment with metformin was associated with inhibition of mTOR/p70S6K/pS6 signaling and downregulation of pERK in both TT and MZ-CRC-1 cells. Metformin had no significant effects on pAKT in the cell lines examined. Metformin-inducible AMPK activation was noted only in TT cells. Treatment with AMPK inhibitor (compound C) or AMPK silencing did not prevent growth inhibitory effects of metformin in TT cells. Metformin had no effect on MTC cell migration but reduced the ability of cells to form multicellular spheroids in nonadherent conditions. Immunostaining of human MTC showed over-expression of cyclin D1 in all tumors compared with corresponding normal tissue. Activation of mTOR/p70S6K was detected in 8/14 (57.1%) examined tumors. Together, these findings indicate that growth inhibitory effects in MTC cells are associated with downregulation of both mTOR/6SK and pERK signaling pathways. Expression of metformin's molecular targets in human MTC cells suggests its potential utility for the treatment of MTC in patients.

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The rapamycin-derivative RAD001 (everolimus) inhibits cell viability and interacts with the Akt–mTOR–p70S6K pathway in human medullary thyroid carcinoma cells

Cited by 34 publications

References 37 publications

Activation of the mTOR Pathway in Primary Medullary Thyroid Carcinoma and Lymph Node Metastases

Activation of the mTOR Pathway in Primary Medullary Thyroid Carcinoma and Lymph Node Metastases

mTOR activation in medullary thyroid carcinoma with RAS mutation

Metformin inhibits growth and decreases resistance to anoikis in medullary thyroid cancer cells

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