Similarities of prosurvival signals in Bcl-2-positive and Bcl-2-negative follicular lymphomas identified by reverse phase protein microarray.
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.
Zha
Hongbin
H
Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Raffeld
Mark
M
Charboneau
Lu
L
Pittaluga
Stefania
S
Kwak
Larry W
LW
Petricoin
Emanuel
E
Liotta
Lance A
LA
Jaffe
Elaine S
ES
D017209:Apoptosis / Q000502:physiology*; D014408:Biomarkers, Tumor / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002455:Cell Division; D002470:Cell Survival; D004273:DNA, Neoplasm / Q000032:analysis; D015326:Gene Rearrangement, B-Lymphocyte, Heavy Chain / Q000235:genetics; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D051034:Inhibitor of Apoptosis Proteins; D008198:Lymph Nodes / Q000378:metabolism* / Q000473:pathology; D008224:Lymphoma, Follicular / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009363:Neoplasm Proteins; D009367:Neoplasm Staging; D040081:Protein Array Analysis; D017346:Protein Serine-Threonine Kinases; D040901:Proteomics; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D000077022:Survivin; D051028:bcl-2-Associated X Protein; D051025:bcl-Associated Death Protein
C494819:BAD protein, human; C494826:BAX protein, human; C107489:BIRC5 protein, human; D014408:Biomarkers, Tumor; D002352:Carrier Proteins; D004273:DNA, Neoplasm; D007143:Immunoglobulin Heavy Chains; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D000077022:Survivin; D051028:bcl-2-Associated X Protein; D051025:bcl-Associated Death Protein; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt