Targeted disruption of FANCC and FANCG in human cancer provides a preclinical model for specific therapeutic options.
OBJECTIVE
How specifically to treat pancreatic and other cancers harboring Fanconi anemia gene mutations has raised great interest recently, yet preclinical studies have been hampered by the lack of well-controlled human cancer models.


METHODS
We endogenously disrupted FANCC and FANCG in a human adenocarcinoma cell line and determined the impact of these genes on drug sensitivity, irradiation sensitivity, and genome maintenance.


RESULTS
FANCC and FANCG disruption abrogated FANCD2 monoubiquitination, confirming an impaired Fanconi anemia pathway function. On treatment with DNA interstrand-cross-linking agents, FANCC and FANCG disruption caused increased clastogenic damage, G2/M arrest, and decreased proliferation. The extent of hypersensitivity varied among agents, with ratios of inhibitory concentration 50% ranging from 2-fold for oxaliplatin to 14-fold for melphalan, a drug infrequently used in solid tumors. No hypersensitivity was observed on gemcitabine, etoposide, 3-aminobenzamide, NU1025, or hydrogen peroxide. FANCC and FANCG disruption also resulted in increased clastogenic damage on irradiation, but only FANCG disruption caused a subsequent decrease in relative survival. Finally, FANCC and FANCG disruption increased spontaneous chromosomal breakage, supporting the role of these genes in genome maintenance and likely explaining why they are mutated in sporadic cancer.


CONCLUSIONS
Our human cancer cell model provides optimal controls to elucidate fundamental biologic features of individual Fanconi anemia gene defects and facilitates preclinical studies of therapeutic options. The impact of Fanconi gene defects on drug and irradiation sensitivity renders these genes promising targets for a specific, genotype-based therapy for individual cancer patients, providing a strong rationale for clinical trials.
Gallmeier
Eike
E
The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, Baltimore, Maryland, USA.
Calhoun
Eric S
ES
Rago
Carlo
C
Brody
Jonathan R
JR
Cunningham
Steven C
SC
Hucl
Tomas
T
Gorospe
Myriam
M
Kohli
Manu
M
Lengauer
Christoph
C
Kern
Scott E
SE
D000230:Adenocarcinoma / Q000188:drug therapy / Q000235:genetics*; D000483:Alleles; D000970:Antineoplastic Agents / Q000494:pharmacology; D015153:Blotting, Western; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D019457:Chromosome Breakage / Q000235:genetics*; D052218:Fanconi Anemia Complementation Group C Protein / Q000187:drug effects / Q000235:genetics*; D052241:Fanconi Anemia Complementation Group G Protein / Q000187:drug effects / Q000235:genetics*; D006801:Humans; D047468:Immunoprecipitation; D017403:In Situ Hybridization; D007621:Karyotyping; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity
D000970:Antineoplastic Agents; D052218:Fanconi Anemia Complementation Group C Protein; D052241:Fanconi Anemia Complementation Group G Protein