Fem1b, a proapoptotic protein, mediates proteasome inhibitor-induced apoptosis of human colon cancer cells

M. Cecilia Subauste, Owen J. Sansom, Nehal Porecha, Natacha Raich, Liqin Du, Joseph F. Maher

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

In the treatment of colon cancer, the development of resistance to apoptosis is a major factor in resistance to therapy. New molecular approaches to overcome apoptosis resistance, such as selectively upregulating proapoptotic proteins, are needed in colon cancer therapy. In a mouse model with inactivation of the adenomatous polyposis coli (Apc) tumor suppressor gene, reflecting the pathogenesis of most human colon cancers, the gene encoding feminization-1 homolog b (Fem1b) is upregulated in intestinal epithelium following Apc inactivation. Fem1b is a proapoptotic protein that interacts with apoptosis-inducing proteins Fas, tumor necrosis factor receptor-1 (TNFR1), and apoptotic protease activating factor-1 (Apaf-1). Increasing Fem1b expression induces apoptosis of cancer cells, but effects on colon cancer cells have not been reported. Fem1b is a homolog of feminization-1 (FEM-1), a protein in Caenorhabditis elegans that is regulated by proteasomal degradation, but whether Fem1b is likewise regulated by proteasomal degradation is unknown. Herein, we found that Fem1b protein is expressed in primary human colon cancer specimens, and in malignant SW620, HCT-116, and DLD-1 colon cancer cells. Increasing Fem1b expression, by transfection of a Fem1b expression construct, induced apoptosis of these cells. We found that proteasome inhibitor treatment of SW620, HCT-116, and DLD-1 cells caused upregulation of Fem1b protein levels, associated with induction of apoptosis. Blockade of Fem1b upregulation with morpholino antisense oligonucleotide suppressed the proteasome inhibitor-induced apoptosis of these cells. In conclusion, the proapoptotic protein Fem1b is downregulated by the proteasome in malignant colon cancer cells and mediates proteasome inhibitor-induced apoptosis of these cells. Therefore, Fem1b could represent a novel molecular target to overcome apoptosis resistance in therapy of colon cancer.

Original languageEnglish (US)
Pages (from-to)105-113
Number of pages9
JournalMolecular Carcinogenesis
Volume49
Issue number2
DOIs
StatePublished - Feb 2010
Externally publishedYes

Fingerprint

Feminization
Proteasome Inhibitors
Colonic Neoplasms
Apoptosis
Proteins
Adenomatous Polyposis Coli
Apoptotic Protease-Activating Factor 1
Up-Regulation
Caenorhabditis elegans Proteins
Morpholinos
Apoptosis Regulatory Proteins
R Factors
Antisense Oligonucleotides
Tumor Necrosis Factor Receptors
Neoplasm Genes
Proteasome Endopeptidase Complex
Intestinal Mucosa
Tumor Suppressor Genes

Keywords

  • Apoptosis
  • Colon cancer
  • Fem1b
  • Proteasome inhibitor

ASJC Scopus subject areas

  • Cancer Research
  • Molecular Biology

Cite this

Fem1b, a proapoptotic protein, mediates proteasome inhibitor-induced apoptosis of human colon cancer cells. / Subauste, M. Cecilia; Sansom, Owen J.; Porecha, Nehal; Raich, Natacha; Du, Liqin; Maher, Joseph F.

In: Molecular Carcinogenesis, Vol. 49, No. 2, 02.2010, p. 105-113.

Research output: Contribution to journalArticle

Subauste, M. Cecilia ; Sansom, Owen J. ; Porecha, Nehal ; Raich, Natacha ; Du, Liqin ; Maher, Joseph F. / Fem1b, a proapoptotic protein, mediates proteasome inhibitor-induced apoptosis of human colon cancer cells. In: Molecular Carcinogenesis. 2010 ; Vol. 49, No. 2. pp. 105-113.
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