The somatostatin analogue octreotide confers sensitivity to rapamycin treatment on pituitary tumor cells

Vesna Cerovac, Jose Monteserin-Garcia, Hadara Rubinfeld, Michael Buchfelder, Marco Losa, Tullio Florio, Marcelo Paez-Pereda, Günter K. Stalla, Marily Theodoropoulou

Research output: Contribution to journalArticle

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Abstract

Rapamycin and its analogues have significant antiproliferative action against a variety of tumors. However, sensitivity to rapamycin is reduced by Akt activation that results from the ablative effects of rapamycin on a p70 S6K-induced negative feedback loop that blunts phosphoinositide 3-kinase (PI3K)-mediated support for Akt activity. Thus, sensitivity to rapamycin might be increased by imposing an upstream blockade to the PI3K/Akt pathway. Here, we investigated this model using the somatostatin analogue octreotide as a tool to decrease levels of activated Ser473-phosphorylated Akt (pAkt-Ser 473) in pituitary tumor cells that express somatostatin receptors. Octreotide increased levels of phosphorylated insulin receptor substrate-1 that were suppressed by rapamycin, subsequently decreasing levels of pAkt-Ser 473 through effects on phosphotyrosine phosphatase SHP-1. Octreotide potentiated the antiproliferative effects of rapamycin in immortalized pituitary tumor cells or human nonfunctioning pituitary adenoma cells in primary cell culture, sensitizing tumor cells even to low rapamycin concentrations. Combined treatment of octreotide and rapamycin triggered G1 cell cycle arrest, decreasing E2F transcriptional activity and cyclin E levels by increasing levels of p27/Kip1. These findings show that adjuvant treatment with a somatostatin analogue can sensitize pituitary tumor cells to the antiproliferative effects of rapamycin.

Original languageEnglish
Pages (from-to)666-674
Number of pages9
JournalCancer Research
Volume70
Issue number2
DOIs
Publication statusPublished - Jan 15 2010

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Octreotide
Pituitary Neoplasms
Sirolimus
Somatostatin
1-Phosphatidylinositol 4-Kinase
G1 Phase Cell Cycle Checkpoints
Insulin Receptor Substrate Proteins
Cyclin E
Somatostatin Receptors
Protein Tyrosine Phosphatases
Primary Cell Culture
Neoplasms

ASJC Scopus subject areas

  • Cancer Research
  • Oncology

Cite this

Cerovac, V., Monteserin-Garcia, J., Rubinfeld, H., Buchfelder, M., Losa, M., Florio, T., ... Theodoropoulou, M. (2010). The somatostatin analogue octreotide confers sensitivity to rapamycin treatment on pituitary tumor cells. Cancer Research, 70(2), 666-674. https://doi.org/10.1158/0008-5472.CAN-09-2951

The somatostatin analogue octreotide confers sensitivity to rapamycin treatment on pituitary tumor cells. / Cerovac, Vesna; Monteserin-Garcia, Jose; Rubinfeld, Hadara; Buchfelder, Michael; Losa, Marco; Florio, Tullio; Paez-Pereda, Marcelo; Stalla, Günter K.; Theodoropoulou, Marily.

In: Cancer Research, Vol. 70, No. 2, 15.01.2010, p. 666-674.

Research output: Contribution to journalArticle

Cerovac, V, Monteserin-Garcia, J, Rubinfeld, H, Buchfelder, M, Losa, M, Florio, T, Paez-Pereda, M, Stalla, GK & Theodoropoulou, M 2010, 'The somatostatin analogue octreotide confers sensitivity to rapamycin treatment on pituitary tumor cells', Cancer Research, vol. 70, no. 2, pp. 666-674. https://doi.org/10.1158/0008-5472.CAN-09-2951
Cerovac, Vesna ; Monteserin-Garcia, Jose ; Rubinfeld, Hadara ; Buchfelder, Michael ; Losa, Marco ; Florio, Tullio ; Paez-Pereda, Marcelo ; Stalla, Günter K. ; Theodoropoulou, Marily. / The somatostatin analogue octreotide confers sensitivity to rapamycin treatment on pituitary tumor cells. In: Cancer Research. 2010 ; Vol. 70, No. 2. pp. 666-674.
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