Activation of the AKT and mammalian target of rapamycin pathways and the inhibitory effects of rapamycin on those pathways in canine malignant melanoma cell lines

Michael S Kent, Cameron J. Collins, Fang Ye

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Objective - To investigate the activation of the AKT and mammalian target of rapamycin (mTOR) pathways and assess the inhibitory effects of rapamycin on those pathways in canine malignant melanoma cells. Sample Population - 3 established primary canine melanoma cell lines generated from naturally occurring tumors. Procedures - Expressions of total and phosphorylated AKT, mTOR, and p70 ribosomal S6 kinase 1 (p70S6K) in canine melanoma cells that were or were not exposed to 10nM rapamycin were assessed via western blot analysis. Clonogenic assays were performed to determine the surviving fraction of melanoma cells after exposure to 0.1, 1, 10, or 100nM rapamycin. Results - Expressions of total and phosphorylated AKT, mTOR, and p7086K proteins were detected (ie, the AKT and mTOR pathways were activated) in all 3 cell lines. Rapamycin treatment resulted in decreases in phosphorylated mTOR expression and phosphorylated p70S6K expression but no change in phosphorylated AKT expression. Expression of total AKT, mTOR, and p70S6K persisted after rapamycin treatment. There was a significant dose-dependent decrease in surviving tumor cell fraction for each cell line following treatment with rapamycin. Conclusions and Clinical Relevance - These data indicated that AKT and mTOR, as well as their downstream product p70S6K, are present and active in canine melanoma cells. Activation of the mTOR pathway can be inhibited by rapamycin; treatment of melanoma cells with rapamycin decreased the surviving tumor cell fraction. Use of mTOR inhibitors as antineoplastic treatments in dogs with melanoma warrants investigation. Furthermore, these data upport the use of canine melanoma cells as a molecular model for melanoma in humans.

Original languageEnglish (US)
Pages (from-to)263-269
Number of pages7
JournalAmerican Journal of Veterinary Research
Volume70
Issue number2
DOIs
StatePublished - Feb 2009

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Sirolimus
melanoma
Canidae
Melanoma
cell lines
Cell Line
dogs
phosphotransferases (kinases)
70-kDa Ribosomal Protein S6 Kinases
cells
molecular models
TOR Serine-Threonine Kinases
Western blotting
Neoplasms
Molecular Models
neoplasms
assays
Antineoplastic Agents
dosage

ASJC Scopus subject areas

  • veterinary(all)

Cite this

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title = "Activation of the AKT and mammalian target of rapamycin pathways and the inhibitory effects of rapamycin on those pathways in canine malignant melanoma cell lines",
abstract = "Objective - To investigate the activation of the AKT and mammalian target of rapamycin (mTOR) pathways and assess the inhibitory effects of rapamycin on those pathways in canine malignant melanoma cells. Sample Population - 3 established primary canine melanoma cell lines generated from naturally occurring tumors. Procedures - Expressions of total and phosphorylated AKT, mTOR, and p70 ribosomal S6 kinase 1 (p70S6K) in canine melanoma cells that were or were not exposed to 10nM rapamycin were assessed via western blot analysis. Clonogenic assays were performed to determine the surviving fraction of melanoma cells after exposure to 0.1, 1, 10, or 100nM rapamycin. Results - Expressions of total and phosphorylated AKT, mTOR, and p7086K proteins were detected (ie, the AKT and mTOR pathways were activated) in all 3 cell lines. Rapamycin treatment resulted in decreases in phosphorylated mTOR expression and phosphorylated p70S6K expression but no change in phosphorylated AKT expression. Expression of total AKT, mTOR, and p70S6K persisted after rapamycin treatment. There was a significant dose-dependent decrease in surviving tumor cell fraction for each cell line following treatment with rapamycin. Conclusions and Clinical Relevance - These data indicated that AKT and mTOR, as well as their downstream product p70S6K, are present and active in canine melanoma cells. Activation of the mTOR pathway can be inhibited by rapamycin; treatment of melanoma cells with rapamycin decreased the surviving tumor cell fraction. Use of mTOR inhibitors as antineoplastic treatments in dogs with melanoma warrants investigation. Furthermore, these data upport the use of canine melanoma cells as a molecular model for melanoma in humans.",
author = "Kent, {Michael S} and Collins, {Cameron J.} and Fang Ye",
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AU - Collins, Cameron J.

AU - Ye, Fang

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N2 - Objective - To investigate the activation of the AKT and mammalian target of rapamycin (mTOR) pathways and assess the inhibitory effects of rapamycin on those pathways in canine malignant melanoma cells. Sample Population - 3 established primary canine melanoma cell lines generated from naturally occurring tumors. Procedures - Expressions of total and phosphorylated AKT, mTOR, and p70 ribosomal S6 kinase 1 (p70S6K) in canine melanoma cells that were or were not exposed to 10nM rapamycin were assessed via western blot analysis. Clonogenic assays were performed to determine the surviving fraction of melanoma cells after exposure to 0.1, 1, 10, or 100nM rapamycin. Results - Expressions of total and phosphorylated AKT, mTOR, and p7086K proteins were detected (ie, the AKT and mTOR pathways were activated) in all 3 cell lines. Rapamycin treatment resulted in decreases in phosphorylated mTOR expression and phosphorylated p70S6K expression but no change in phosphorylated AKT expression. Expression of total AKT, mTOR, and p70S6K persisted after rapamycin treatment. There was a significant dose-dependent decrease in surviving tumor cell fraction for each cell line following treatment with rapamycin. Conclusions and Clinical Relevance - These data indicated that AKT and mTOR, as well as their downstream product p70S6K, are present and active in canine melanoma cells. Activation of the mTOR pathway can be inhibited by rapamycin; treatment of melanoma cells with rapamycin decreased the surviving tumor cell fraction. Use of mTOR inhibitors as antineoplastic treatments in dogs with melanoma warrants investigation. Furthermore, these data upport the use of canine melanoma cells as a molecular model for melanoma in humans.

AB - Objective - To investigate the activation of the AKT and mammalian target of rapamycin (mTOR) pathways and assess the inhibitory effects of rapamycin on those pathways in canine malignant melanoma cells. Sample Population - 3 established primary canine melanoma cell lines generated from naturally occurring tumors. Procedures - Expressions of total and phosphorylated AKT, mTOR, and p70 ribosomal S6 kinase 1 (p70S6K) in canine melanoma cells that were or were not exposed to 10nM rapamycin were assessed via western blot analysis. Clonogenic assays were performed to determine the surviving fraction of melanoma cells after exposure to 0.1, 1, 10, or 100nM rapamycin. Results - Expressions of total and phosphorylated AKT, mTOR, and p7086K proteins were detected (ie, the AKT and mTOR pathways were activated) in all 3 cell lines. Rapamycin treatment resulted in decreases in phosphorylated mTOR expression and phosphorylated p70S6K expression but no change in phosphorylated AKT expression. Expression of total AKT, mTOR, and p70S6K persisted after rapamycin treatment. There was a significant dose-dependent decrease in surviving tumor cell fraction for each cell line following treatment with rapamycin. Conclusions and Clinical Relevance - These data indicated that AKT and mTOR, as well as their downstream product p70S6K, are present and active in canine melanoma cells. Activation of the mTOR pathway can be inhibited by rapamycin; treatment of melanoma cells with rapamycin decreased the surviving tumor cell fraction. Use of mTOR inhibitors as antineoplastic treatments in dogs with melanoma warrants investigation. Furthermore, these data upport the use of canine melanoma cells as a molecular model for melanoma in humans.

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