Knockdown of Slingshot 2 (SSH2) serine phosphatase induces Caspase3 activation in human carcinoma cell lines with the loss of the Birt-Hogg-Dubé tumour suppressor gene (FLCN)

X Lu, U Boora, L Seabra, E M Rabai, J Fenton, A Reiman, Z Nagy, E R Maher

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Birt-Hogg-Dubé (BHD) syndrome, is a dominantly inherited familial cancer syndrome associated with susceptibility to renal cell carcinoma (RCC) caused by inactivating mutations in the folliculin (FLCN) gene. The precise functions of the FLCN gene product are still under investigation but RCC from BHD patients show loss of the wild-type allele consistent with a tumor suppressor gene function. In a search for potential synthetic-lethal targets for FLCN using a phosphatase siRNA library screening approach, we found that knockdown of SSH2 serine phosphatase (one of the three members of Slingshot family and previously implicated in actin reorganization) specifically induced Caspase3/7 activity in a dose-dependent manner (up to six-fold increase, 10 nM, 72 h) in two human FLCN-deficient cell lines (BHD-origin renal cell carcinoma UOK257 and thyroid carcinoma FTC133) but not in their folliculin expressing isogenic cell lines. SSH2 siRNA-induced knockdown was accompanied by increased expression of SSH1 and SSH3 (suggesting a compensatory regulatory mechanism among members of SSH family). FLCN-null cells exhibited evidence of dysregulated cofilin de/phosphorylation pathways. Knockdown of SSH2 in FLCN-null cells was associated with an alteration in cell cycle kinetics (20% increase in G1, 30% and 40% decrease in S and G2M, respectively). Combination treatment of multiple SSH family (SSH2 plus SSH1 and/or SSH3) siRNAs potentiated induction of Caspase3/7 activity and changes in the cell cycle kinetics. These data indicate that: (a) apoptotic cell death in FLCN-null cells can be triggered by SSH2 knockdown through cell cycle arrest; (b) SSH2 represents a potential therapeutic target for the development of agents for the treatment of BHD syndrome and, possibly, related tumors.

Original languageEnglish
Pages (from-to)956-965
Number of pages10
JournalOncogene
Volume33
Issue number8
Early online date18 Feb 2013
DOIs
Publication statusPublished - 20 Feb 2014
Externally publishedYes

Fingerprint

Estrone
Tumor Suppressor Genes
Phosphoric Monoester Hydrolases
Serine
Carcinoma
Cell Line
Null Lymphocytes
Renal Cell Carcinoma
Small Interfering RNA
Cell Cycle
Actin Depolymerizing Factors
Cell Cycle Checkpoints
Thyroid Neoplasms
Genes
Actins
Neoplasms
Cell Death
Therapeutics
Alleles
Phosphorylation

Keywords

  • Carcinoma, Renal Cell
  • Caspase 3
  • Cell Line, Tumor
  • Enzyme Activation
  • Gene Knockdown Techniques
  • Genes, Tumor Suppressor
  • Humans
  • Kidney Neoplasms
  • Phosphoprotein Phosphatases
  • Proto-Oncogene Proteins
  • Real-Time Polymerase Chain Reaction
  • Thyroid Neoplasms
  • Tumor Suppressor Proteins
  • Journal Article
  • Research Support, Non-U.S. Gov't
  • Birt–Hogg–Dube
  • Folicullin
  • Slingshot phosphatases
  • Synthetic lethality
  • Caspase
  • Therapeutic target

Cite this

Knockdown of Slingshot 2 (SSH2) serine phosphatase induces Caspase3 activation in human carcinoma cell lines with the loss of the Birt-Hogg-Dubé tumour suppressor gene (FLCN). / Lu, X; Boora, U; Seabra, L; Rabai, E M; Fenton, J; Reiman, A; Nagy, Z; Maher, E R.

In: Oncogene, Vol. 33, No. 8, 20.02.2014, p. 956-965.

Research output: Contribution to journalArticle

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abstract = "Birt-Hogg-Dub{\'e} (BHD) syndrome, is a dominantly inherited familial cancer syndrome associated with susceptibility to renal cell carcinoma (RCC) caused by inactivating mutations in the folliculin (FLCN) gene. The precise functions of the FLCN gene product are still under investigation but RCC from BHD patients show loss of the wild-type allele consistent with a tumor suppressor gene function. In a search for potential synthetic-lethal targets for FLCN using a phosphatase siRNA library screening approach, we found that knockdown of SSH2 serine phosphatase (one of the three members of Slingshot family and previously implicated in actin reorganization) specifically induced Caspase3/7 activity in a dose-dependent manner (up to six-fold increase, 10 nM, 72 h) in two human FLCN-deficient cell lines (BHD-origin renal cell carcinoma UOK257 and thyroid carcinoma FTC133) but not in their folliculin expressing isogenic cell lines. SSH2 siRNA-induced knockdown was accompanied by increased expression of SSH1 and SSH3 (suggesting a compensatory regulatory mechanism among members of SSH family). FLCN-null cells exhibited evidence of dysregulated cofilin de/phosphorylation pathways. Knockdown of SSH2 in FLCN-null cells was associated with an alteration in cell cycle kinetics (20{\%} increase in G1, 30{\%} and 40{\%} decrease in S and G2M, respectively). Combination treatment of multiple SSH family (SSH2 plus SSH1 and/or SSH3) siRNAs potentiated induction of Caspase3/7 activity and changes in the cell cycle kinetics. These data indicate that: (a) apoptotic cell death in FLCN-null cells can be triggered by SSH2 knockdown through cell cycle arrest; (b) SSH2 represents a potential therapeutic target for the development of agents for the treatment of BHD syndrome and, possibly, related tumors.",
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AB - Birt-Hogg-Dubé (BHD) syndrome, is a dominantly inherited familial cancer syndrome associated with susceptibility to renal cell carcinoma (RCC) caused by inactivating mutations in the folliculin (FLCN) gene. The precise functions of the FLCN gene product are still under investigation but RCC from BHD patients show loss of the wild-type allele consistent with a tumor suppressor gene function. In a search for potential synthetic-lethal targets for FLCN using a phosphatase siRNA library screening approach, we found that knockdown of SSH2 serine phosphatase (one of the three members of Slingshot family and previously implicated in actin reorganization) specifically induced Caspase3/7 activity in a dose-dependent manner (up to six-fold increase, 10 nM, 72 h) in two human FLCN-deficient cell lines (BHD-origin renal cell carcinoma UOK257 and thyroid carcinoma FTC133) but not in their folliculin expressing isogenic cell lines. SSH2 siRNA-induced knockdown was accompanied by increased expression of SSH1 and SSH3 (suggesting a compensatory regulatory mechanism among members of SSH family). FLCN-null cells exhibited evidence of dysregulated cofilin de/phosphorylation pathways. Knockdown of SSH2 in FLCN-null cells was associated with an alteration in cell cycle kinetics (20% increase in G1, 30% and 40% decrease in S and G2M, respectively). Combination treatment of multiple SSH family (SSH2 plus SSH1 and/or SSH3) siRNAs potentiated induction of Caspase3/7 activity and changes in the cell cycle kinetics. These data indicate that: (a) apoptotic cell death in FLCN-null cells can be triggered by SSH2 knockdown through cell cycle arrest; (b) SSH2 represents a potential therapeutic target for the development of agents for the treatment of BHD syndrome and, possibly, related tumors.

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KW - Journal Article

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KW - Birt–Hogg–Dube

KW - Folicullin

KW - Slingshot phosphatases

KW - Synthetic lethality

KW - Caspase

KW - Therapeutic target

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