Similarities of prosurvival signals in Bcl-2-positive and Bcl-2-negative follicular lymphomas identified by reverse phase protein microarray

Lab Invest. 2004 Feb;84(2):235-44. doi: 10.1038/labinvest.3700051.

Abstract

Overexpression of Bcl-2 protein has been known to play a role in the pathogenesis of follicular lymphoma (FL). However, 10-15% of FLs are negative for Bcl-2 by immunohistochemistry, raising the possibility that another gene product(s) may provide prosurvival signal(s). We used reverse phase protein microarray to analyze lysates of follicle center cells isolated by laser capture microdissection from: Bcl-2+ FL, Bcl-2- FL and reactive follicular hyperplasia (FH) (nine cases each group). TUNEL assay confirmed similar and reduced levels of apoptosis in Bcl-2+ FL and Bcl-2- FL, indicating the likelihood of Bcl-2-independent inhibition of apoptosis. Arrays were quantitatively analyzed with antibodies to proteins involved in the apoptotic pathway. As expected, Bcl-2 levels were up to eight-fold higher in Bcl-2+ FL than in FH and Bcl-2- FL. However, there was no difference in levels of Mcl-1 and survivin among these three groups. Bcl-X(L) showed a trend for increased expression in Bcl-2- FL as compared with Bcl-2+ FL, although the differences did not reach statistical significance (P>0.1). The increase in Bcl-X(L) may provide an alternative antiapoptotic signal in FL negative for Bcl-2 protein. Interestingly, Bax expression was higher in FL (Bcl-2+ or -) than in FH (P=0.001). Notably, phospho-Akt (Ser-473) was increased in FL (Bcl-2+ or -) (P<0.03) with increased phospho-Bad (Ser-136), as compared with levels in FH. The activation of the Akt/Bad pathway provides further evidence of prosurvival signals in FL, independent of Bcl-2 alone. These data suggest that nodal FL represents a single disease with a final common biochemical pathway.

MeSH terms

  • Apoptosis / physiology*
  • Biomarkers, Tumor / metabolism
  • Carrier Proteins / metabolism
  • Cell Division
  • Cell Survival
  • DNA, Neoplasm / analysis
  • Gene Rearrangement, B-Lymphocyte, Heavy Chain / genetics
  • Humans
  • Image Processing, Computer-Assisted
  • Immunoglobulin Heavy Chains / genetics
  • Immunohistochemistry
  • In Situ Nick-End Labeling
  • Inhibitor of Apoptosis Proteins
  • Lymph Nodes / metabolism*
  • Lymph Nodes / pathology
  • Lymphoma, Follicular / genetics
  • Lymphoma, Follicular / metabolism*
  • Lymphoma, Follicular / pathology
  • Microtubule-Associated Proteins / metabolism
  • Neoplasm Proteins
  • Neoplasm Staging
  • Protein Array Analysis*
  • Protein-Serine-Threonine Kinases*
  • Proteomics
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-akt
  • Proto-Oncogene Proteins c-bcl-2 / genetics
  • Proto-Oncogene Proteins c-bcl-2 / metabolism*
  • Signal Transduction
  • Survivin
  • bcl-2-Associated X Protein
  • bcl-Associated Death Protein

Substances

  • BAD protein, human
  • BAX protein, human
  • BIRC5 protein, human
  • Biomarkers, Tumor
  • Carrier Proteins
  • DNA, Neoplasm
  • Immunoglobulin Heavy Chains
  • Inhibitor of Apoptosis Proteins
  • Microtubule-Associated Proteins
  • Neoplasm Proteins
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • Survivin
  • bcl-2-Associated X Protein
  • bcl-Associated Death Protein
  • AKT1 protein, human
  • Protein-Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt