PMID- 14555534
OWN - NLM
STAT- MEDLINE
DCOM- 20040520
LR  - 20161124
IS  - 1078-0432 (Print)
IS  - 1078-0432 (Linking)
VI  - 9
IP  - 12
DP  - 2003 Oct 1
TI  - Flavopiridol potently induces small cell lung cancer apoptosis during S phase in 
      a manner that involves early mitochondrial dysfunction.
PG  - 4586-94
AB  - PURPOSE: Accumulating evidence indicates that small cell lung cancer (SCLC) is 
      defective in many of the regulatory mechanisms that control cell cycle 
      progression. The purpose of this study was to determine the effects of 
      flavopiridol, a pan-cyclin-dependent kinase inhibitor, on growth and apoptosis of 
      SCLC cell lines. EXPERIMENTAL DESIGN: Cell growth was monitored using 
      3-(4,5dimethylthiazol-2yl)-2,5-diphenyl-tetrazolium bromide (MTT) and clonogenic 
      assays. Induction of apoptosis was assessed using multiple assays, including flow 
      cytometric determination of DNA content and mitochondrial membrane potential, 
      terminal deoxynucleotide transferase-mediated dUTP nick end labeling (TUNEL), and 
      Western blot analysis of procaspase 3 and poly(ADP-ribose) polymerase cleavage. 
      RESULTS: Flavopiridol induced growth inhibition and cytotoxicity in multiple SCLC 
      cell lines, with an IC(50) of 50-100 nM and an LD(50) of 150-200 nM in 72-h MTT 
      assays. The cytotoxicity seen in the MTT assay proved to be apoptosis by several 
      criteria. Interestingly, inhibition of caspase activation with the caspase 
      inhibitor Boc-Asp(OMe)-CH(2)F reduced TUNEL labeling by 40% but did not have any 
      effect on the loss of mitochondrial membrane potential (detected as early as 4 h 
      after drug exposure) or cytotoxicity in MTT assays. These results suggest that 
      the primary event in flavopiridol-induced apoptosis involves induction of 
      mitochondrial dysfunction. Cells synchronized with aphidicolin at the G(1)-S 
      border and treated with flavopiridol during S phase showed a marked increase in 
      apoptosis compared with an asynchronous population or a population treated during 
      G(2)-M. Despite the increased apoptosis, a significant proportion of synchronized 
      cells proceeded through S, G(2)-M, and into G(1) phase in the presence of 
      flavopiridol, demonstrating that a high-grade cell cycle arrest is not required 
      for apoptosis. Cells synchronized at the G(1)-S border treated with a short 
      exposure to flavopiridol also showed more than a 10-fold decrease in 
      clonogenicity compared with asynchronous cells treated identically. CONCLUSIONS: 
      Taken together, these data demonstrate that flavopiridol potently and selectively 
      induces SCLC apoptosis preferentially during S phase, in a manner that involves 
      early mitochondrial dysfunction without a requirement for a high-grade block to 
      cell cycle progression. Furthermore, clonogenicity data suggests that prior S 
      phase synchronization could be a highly effective way of enhancing the efficacy 
      of bolus or short infusions of flavopiridol in the clinical setting.
FAU - Litz, Julie
AU  - Litz J
AD  - Department of Medicine, Medical College of Virginia/Virginia Commonwealth 
      University, Richmond, Virginia 23249, USA.
FAU - Carlson, Patricia
AU  - Carlson P
FAU - Warshamana-Greene, G Sakuntala
AU  - Warshamana-Greene GS
FAU - Grant, Steven
AU  - Grant S
FAU - Krystal, Geoffrey W
AU  - Krystal GW
LA  - eng
PT  - Journal Article
PT  - Research Support, U.S. Gov't, Non-P.H.S.
PL  - United States
TA  - Clin Cancer Res
JT  - Clinical cancer research : an official journal of the American Association for 
      Cancer Research
JID - 9502500
RN  - 0 (Enzyme Inhibitors)
RN  - 0 (Flavonoids)
RN  - 0 (Piperidines)
RN  - 0 (Tetrazolium Salts)
RN  - 0 (Thiazoles)
RN  - 38966-21-1 (Aphidicolin)
RN  - 45AD6X575G (alvocidib)
RN  - EC 2.4.2.30 (Poly(ADP-ribose) Polymerases)
RN  - EC 3.4.22.- (CASP3 protein, human)
RN  - EC 3.4.22.- (Caspase 3)
RN  - EC 3.4.22.- (Caspases)
RN  - EUY85H477I (thiazolyl blue)
SB  - IM
MH  - Aphidicolin/pharmacology
MH  - Apoptosis/*drug effects
MH  - Blotting, Western
MH  - Carcinoma, Small Cell/metabolism/*pathology
MH  - Caspase 3
MH  - Caspases/metabolism
MH  - Cell Division/drug effects
MH  - Enzyme Inhibitors/*pharmacology
MH  - Flavonoids/*pharmacology
MH  - Flow Cytometry
MH  - Humans
MH  - In Situ Nick-End Labeling
MH  - Lung Neoplasms/metabolism/*pathology
MH  - Membrane Potentials/drug effects
MH  - Mitochondria/*drug effects
MH  - Piperidines/*pharmacology
MH  - Poly(ADP-ribose) Polymerases/metabolism
MH  - S Phase/*drug effects
MH  - Tetrazolium Salts
MH  - Thiazoles
MH  - Tumor Cells, Cultured
MH  - Tumor Stem Cell Assay
EDAT- 2003/10/14 05:00
MHDA- 2004/05/21 05:00
CRDT- 2003/10/14 05:00
PHST- 2003/10/14 05:00 [pubmed]
PHST- 2004/05/21 05:00 [medline]
PHST- 2003/10/14 05:00 [entrez]
PST - ppublish
SO  - Clin Cancer Res. 2003 Oct 1;9(12):4586-94.