title: Overexpression of caspase-3s splice variant in locally advanced breast carcinoma is associated with poor response to neoadjuvant chemotherapy.
abstract: OBJECTIVE
  CASP-3 gene gives rise, by alternative splicing to a caspase-3s variant, to the antagonist apoptotic property of caspase-3. Deregulation of splicing in tumor cells favoring the expression of antiapoptotic variants has been reported to contribute to both tumorigenesis and chemoresistance. Thus, we investigated the role of caspase-3 and its splice variant in breast cancer cells.
  
  
  METHODS
  Breast tumor cell lines deficient (MCF-7) and proficient (HBL100) for CASP-3 gene were transfected with each transcript and were characterized for their apoptotic response to cyclophosphamide. Expression of the two transcripts were measured by reverse transcription-PCR in 130 breast carcinomas, including 90 locally advanced tumors treated with neoadjuvant chemotherapy containing cyclophosphamide, epirubicine, and 5-fluorouracil.
  
  
  RESULTS
  Overexpression of caspase-3s variant in caspase-3-transfected cell lines significantly inhibits apoptosis induced by cyclophosphamide (P < 0.0001 for both cell lines). In breast tissues, only caspase-3 levels were higher in carcinomas than in corresponding adjacent normal tissues (P = 0.0396). Locally advanced carcinomas with high levels of caspase-3 (P < 0.0001) and weak levels of caspase-3s (P = 0.0248) were more sensitive to treatment. Therefore, increase in caspase-3s/caspase3 ratio expression was significantly associated with chemoresistance (P = 0.01). Logistic univariate and multivariate analyses realized according to pathologic response confirm that increased caspase-3s expression was indicative of chemoresistance (P = 0.012 and P = 0.026, respectively).
  
  
  CONCLUSIONS
  The results agree with an antagonist function between the two transcripts of caspase-3 and show that their ratio of expression levels may define a subset of locally advanced breast cancer patients who are more likely to benefit from neoadjuvant cyclophosphamide-containing chemotherapy.
authors.affiliation: Laboratory of Molecular Genetics, Institut National de la Sante et de la Recherche Medicale U-517, Centre Georges François Leclerc, 1 rue du professeur Marion, 21034 Dijon cedex, France.
authors.forename: Frédérique
authors.initials: F
authors.lastname: Végran
authors.forename: Romain
authors.initials: R
authors.lastname: Boidot
authors.forename: Claire
authors.initials: C
authors.lastname: Oudin
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Riedinger
authors.forename: Franck
authors.initials: F
authors.lastname: Bonnetain
authors.forename: Sarab
authors.initials: S
authors.lastname: Lizard-Nacol
mesh_terms: D017398:Alternative Splicing; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D017209:Apoptosis / Q000235:genetics*; D001943:Breast Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism; D018270:Carcinoma, Ductal, Breast / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000235:genetics* / Q000378:metabolism; D017024:Chemotherapy, Adjuvant; D003520:Cyclophosphamide / Q000627:therapeutic use; D018450:Disease Progression; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D004792:Enzyme Precursors; D015251:Epirubicin / Q000627:therapeutic use; D005260:Female; D005472:Fluorouracil / Q000627:therapeutic use; D005786:Gene Expression Regulation; D006801:Humans; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D014407:Tumor Cells, Cultured
chemical_list: D061945:Caspase Inhibitors; D004792:Enzyme Precursors; D015251:Epirubicin; D003520:Cyclophosphamide; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D005472:Fluorouracil