cAMP/PKA-induced filamin A (FLNA) phosphorylation inhibits SST2 signal transduction in GH-secreting pituitary tumor cells

E. Peverelli, E. Giardino, F. Mangili, D. Treppiedi, R. Catalano, E. Ferrante, E. Sala, M. Locatelli, A. G. Lania, M. Arosio, A. Spada, G. Mantovani

Research output: Contribution to journalArticle

Abstract

An efficient intracellular response to somatostatin analogs (SSA) in pituitary tumors requires filamin A (FLNA). Since cAMP pathway plays an important role in GH-secreting pituitary tumors pathogenesis and FLNA is phosphorylated by PKA on S2152, aim of this study was to investigate in tumoral somatotrophs the impact of cAMP pathway activation and SSA stimulation on FLNA phosphorylation and the consequences on SST2 function. We found a PKA-mediated increase (2-fold) and SST2 agonist-induced decrease (−50%) of FLNA phosphorylation in GH3, GH4C1 and primary somatotroph tumor cells. This modification regulates FLNA function. Indeed, phosphomimetic S2152D FLNA mutant, but not phosphodeficient S2152A, abolished the known SSA antitumoral effects, namely: 1) inhibition of cell proliferation, reduction of cyclin D3 and increase of p27; 2) increase of cell apoptosis; 3) inhibition of cell migration via RhoA activation and cofilin phosphorylation. Coimmunoprecipitation and immunofluorescence assays showed that S2152A FLNA was recruited to activated SST2, whereas S2152D FLNA constitutively bound SST2 on the plasma membrane, but prevented Gαi proteins recruitment to SST2. In conclusion, we demonstrated that FLNA phosphorylation, promoted by cAMP pathway activation and inhibited by SSA, prevented SST2 signaling in GH-secreting tumoral pituitary cells.
Original languageEnglish
Pages (from-to)101-109
Number of pages9
JournalCancer Letters
Volume435
DOIs
Publication statusPublished - Oct 28 2018

Fingerprint

Filamins
Pituitary Neoplasms
Signal Transduction
Phosphorylation
Somatostatin
Somatotrophs
Cyclin D3
Cell Migration Inhibition
Actin Depolymerizing Factors
Fluorescent Antibody Technique
Cell Proliferation
Cell Membrane
Apoptosis

Keywords

  • cAMP/PKA pathway
  • Cell cytoskeleton
  • Filamin A (FLNA) phosphorylation
  • GH-Secreting pituitary tumors
  • Signal transduction
  • Somatostatin receptor 2 (SST2)

Cite this

cAMP/PKA-induced filamin A (FLNA) phosphorylation inhibits SST2 signal transduction in GH-secreting pituitary tumor cells. / Peverelli, E.; Giardino, E.; Mangili, F.; Treppiedi, D.; Catalano, R.; Ferrante, E.; Sala, E.; Locatelli, M.; Lania, A. G.; Arosio, M.; Spada, A.; Mantovani, G.

In: Cancer Letters, Vol. 435, 28.10.2018, p. 101-109.

Research output: Contribution to journalArticle

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abstract = "An efficient intracellular response to somatostatin analogs (SSA) in pituitary tumors requires filamin A (FLNA). Since cAMP pathway plays an important role in GH-secreting pituitary tumors pathogenesis and FLNA is phosphorylated by PKA on S2152, aim of this study was to investigate in tumoral somatotrophs the impact of cAMP pathway activation and SSA stimulation on FLNA phosphorylation and the consequences on SST2 function. We found a PKA-mediated increase (2-fold) and SST2 agonist-induced decrease (−50{\%}) of FLNA phosphorylation in GH3, GH4C1 and primary somatotroph tumor cells. This modification regulates FLNA function. Indeed, phosphomimetic S2152D FLNA mutant, but not phosphodeficient S2152A, abolished the known SSA antitumoral effects, namely: 1) inhibition of cell proliferation, reduction of cyclin D3 and increase of p27; 2) increase of cell apoptosis; 3) inhibition of cell migration via RhoA activation and cofilin phosphorylation. Coimmunoprecipitation and immunofluorescence assays showed that S2152A FLNA was recruited to activated SST2, whereas S2152D FLNA constitutively bound SST2 on the plasma membrane, but prevented Gαi proteins recruitment to SST2. In conclusion, we demonstrated that FLNA phosphorylation, promoted by cAMP pathway activation and inhibited by SSA, prevented SST2 signaling in GH-secreting tumoral pituitary cells.",
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T1 - cAMP/PKA-induced filamin A (FLNA) phosphorylation inhibits SST2 signal transduction in GH-secreting pituitary tumor cells

AU - Peverelli, E.

AU - Giardino, E.

AU - Mangili, F.

AU - Treppiedi, D.

AU - Catalano, R.

AU - Ferrante, E.

AU - Sala, E.

AU - Locatelli, M.

AU - Lania, A. G.

AU - Arosio, M.

AU - Spada, A.

AU - Mantovani, G.

PY - 2018/10/28

Y1 - 2018/10/28

N2 - An efficient intracellular response to somatostatin analogs (SSA) in pituitary tumors requires filamin A (FLNA). Since cAMP pathway plays an important role in GH-secreting pituitary tumors pathogenesis and FLNA is phosphorylated by PKA on S2152, aim of this study was to investigate in tumoral somatotrophs the impact of cAMP pathway activation and SSA stimulation on FLNA phosphorylation and the consequences on SST2 function. We found a PKA-mediated increase (2-fold) and SST2 agonist-induced decrease (−50%) of FLNA phosphorylation in GH3, GH4C1 and primary somatotroph tumor cells. This modification regulates FLNA function. Indeed, phosphomimetic S2152D FLNA mutant, but not phosphodeficient S2152A, abolished the known SSA antitumoral effects, namely: 1) inhibition of cell proliferation, reduction of cyclin D3 and increase of p27; 2) increase of cell apoptosis; 3) inhibition of cell migration via RhoA activation and cofilin phosphorylation. Coimmunoprecipitation and immunofluorescence assays showed that S2152A FLNA was recruited to activated SST2, whereas S2152D FLNA constitutively bound SST2 on the plasma membrane, but prevented Gαi proteins recruitment to SST2. In conclusion, we demonstrated that FLNA phosphorylation, promoted by cAMP pathway activation and inhibited by SSA, prevented SST2 signaling in GH-secreting tumoral pituitary cells.

AB - An efficient intracellular response to somatostatin analogs (SSA) in pituitary tumors requires filamin A (FLNA). Since cAMP pathway plays an important role in GH-secreting pituitary tumors pathogenesis and FLNA is phosphorylated by PKA on S2152, aim of this study was to investigate in tumoral somatotrophs the impact of cAMP pathway activation and SSA stimulation on FLNA phosphorylation and the consequences on SST2 function. We found a PKA-mediated increase (2-fold) and SST2 agonist-induced decrease (−50%) of FLNA phosphorylation in GH3, GH4C1 and primary somatotroph tumor cells. This modification regulates FLNA function. Indeed, phosphomimetic S2152D FLNA mutant, but not phosphodeficient S2152A, abolished the known SSA antitumoral effects, namely: 1) inhibition of cell proliferation, reduction of cyclin D3 and increase of p27; 2) increase of cell apoptosis; 3) inhibition of cell migration via RhoA activation and cofilin phosphorylation. Coimmunoprecipitation and immunofluorescence assays showed that S2152A FLNA was recruited to activated SST2, whereas S2152D FLNA constitutively bound SST2 on the plasma membrane, but prevented Gαi proteins recruitment to SST2. In conclusion, we demonstrated that FLNA phosphorylation, promoted by cAMP pathway activation and inhibited by SSA, prevented SST2 signaling in GH-secreting tumoral pituitary cells.

KW - cAMP/PKA pathway

KW - Cell cytoskeleton

KW - Filamin A (FLNA) phosphorylation

KW - GH-Secreting pituitary tumors

KW - Signal transduction

KW - Somatostatin receptor 2 (SST2)

U2 - 10.1016/j.canlet.2018.08.002

DO - 10.1016/j.canlet.2018.08.002

M3 - Article

VL - 435

SP - 101

EP - 109

JO - Cancer Letters

JF - Cancer Letters

SN - 0304-3835

ER -