Inhibition of NF-kappa B augments sensitivity to 5-fluorouracil/folinic acid in colon cancer.
BACKGROUND
5-fluorouracil (5-FU), the most common antimetabolite used for the treatment of colorectal cancer, exerts its cytotoxic effects through the induction of apoptosis. Folinic acid potentiates the effect of 5-FU. Drug activity is currently limited as a result of inducible chemoresistance. Limited research suggests that the transcription factor nuclear factor kappa-B (NF-kappaB), which has antiapoptotic properties, may play a major role in inducible chemoresistance.


METHODS
SW48 colon cancer cells were used for all experiments. Cell growth was determined by cell proliferation assay. Apoptosis was assessed by measuring caspase 3 activity. Activation of NF-kappaB was ascertained by electrophoretic mobility shift assay, luciferase reporter assay, and Western blot analysis.


RESULTS
Treatment with 5-FU (0.001-10 mm), not only inhibited growth and induced apoptosis but significantly activated NF-kappaB in SW48 cells. Folinic acid alone (0.01-100 mg/L) did not inhibit growth but improved the cytotoxic effect of 5-FU in a dose-dependent manner. Likewise, folinic acid alone did not activate NF-kappaB or induce apoptosis but enhanced 5-FU-mediated NF-kappaB activation and cell apoptosis. Transfection with adenovirus IkappaBalpha super-repressor strongly inhibited constitutive activation of NF-kappaB and significantly enhanced 5-FU and 5-FU/Folinic acid-mediated growth inhibition (P < 0.05).


CONCLUSIONS
Treatment with 5-FU activates NF-kappaB. Folinic acid enhances 5-FU-mediated activation of NF-kappaB. Inhibition of NF-kappaB enhances the cytotoxic effect of 5-FU with or without Folinic acid in colon cancer cells.
Voboril
Rene
R
Department of Surgery, Division of Surgical Oncology, University of Florida College of Medicine, 1600 SW Archer Road, Room 6184, Gainesville, FL 32610, USA.
Hochwald
Steven N
SN
Li
Jing
J
Brank
Adam
A
Weberova
Jana
J
Wessels
Frank
F
Moldawer
Lyle L
LL
Camp
E Ramsay
ER
MacKay
Sally L D
SL
D000256:Adenoviridae / Q000235:genetics; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000473:pathology* / Q000503:physiopathology; D004357:Drug Synergism; D005472:Fluorouracil / Q000494:pharmacology*; D005822:Genetic Vectors; D006801:Humans; D020672:I-kappa B Proteins / Q000235:genetics / Q000494:pharmacology; D002955:Leucovorin / Q000494:pharmacology*; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000037:antagonists & inhibitors* / Q000187:drug effects / Q000378:metabolism; D014162:Transfection
D000964:Antimetabolites, Antineoplastic; D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D000072000:NF-KappaB Inhibitor alpha; D002955:Leucovorin; D005472:Fluorouracil