We generated loss-of-function human haploid cells for FA complementation group C (FANCC), a gene encoding a component of the FA core complex, and used genome-wide CRISPR libraries as well as insertional mutagenesis to identify synthetic viable (genetic suppressor) interactions for FA.
Lung adenocarcinomas in both male and female patients were associated with (a) genotypic polymorphisms of FANCC and FANCD1; (b) a combined effect of harboring a higher number of high-risk genotypes and smoking/passive smoking; (c) specific interactions of multiple genes, proteins encoded by which have been known to work jointly within the FA pathway.
To understand the function of FA proteins in cellular division events, we investigated the interaction between Stathmin-1 (STMN1) and the FA group C (FANCC) protein.
FANCC mutations are often the cause of FA in patients of Ashkenazi Jewish (AJ) ancestry, and we identified 2 novel FANCC mutations in 2 patients of AJ ancestry.
Mutations in BRCA genes cannot account for all cases of HBOC, indicating that the remaining cases can be attributed to the involvement of constitutive epimutations or other cancer susceptibility genes, which include Fanconi anemia (FA) cluster (FANCD2, FANCA and FANCC), mismatch repair (MMR) cluster (MLH1, MSH2, PMS1, PMS2 and MSH6), DNA repair cluster (ATM, ATR and CHK1/2), and tumor suppressor cluster (TP53, SKT11 and PTEN).
We found that FANCC- and FANCD2-mutant cells were unexpectedly more sensitive to platinum drugs than FANCA-mutant cells, and mono-ubiquitination of FANCD2, which is mediated by the FANCA and FANCC containing FA core complex was not required for platinum resistance.
The c.165+1G>T germline mutation in the 5'ss of exon 2 of the Fanconi anemia C (FANCC) gene commonly predicted to prevent correct splicing was identified in nine FA patients from three pedigrees.
Accordingly, a homozygous inactivating FANCC nonsense mutation (c.553C > T, p.R185X) was identified in HuH-7, resulting in partial transcriptional skipping of exon 6 and leading to the classic cellular FA hypersensitivity phenotype; HuH-7 cells exhibited a strongly reduced proliferation rate and a pronounced G2 cell cycle arrest at distinctly lower concentrations of ICL-agents than a panel of non-isogenic, FA pathway-proficient HCC cell lines.
This finding, coupled with evidence showing that DT40 cells deficient in both FAN1 and FANCC, or FAN1 and FANCJ, exhibited increased sensitivity to cisplatin compared with cells lacking only FAN1, suggests that, despite its association with FANCD2/FANCI, FAN1 in DT40 cells participates in the processing of damage induced by interstrand cross-linking-generating agents also independently of the classical FA pathway.
Tumor necrosis factor alpha (TNF-alpha) production is abnormally high in Fanconi anemia (FA) cells and contributes to the hematopoietic defects seen in FA complementation group C-deficient (Fancc(-/-)) mice.
Here, we show that a 14-hour transduction period allows a foamyviral vector construct expressing the human FANCC cDNA to efficiently transduce murine FA stem cells with 1 to 2 proviral integrations per genome.