ABSTRACT
To identify functions of the fragile tumour suppressor gene, FHIT, matched pairs of Fhit-negative and -positive human cancer cell clones, and normal cell lines established from Fhit -/- and +/+ mice, were stressed and examined for differences in cell cycle kinetics and survival. A larger fraction of Fhit-negative human cancer cells and murine kidney cells survived treatment with mitomycin C or UVC light compared to matched Fhit-positive cells; approximately 10-fold more colonies of Fhit-deficient cells survived high UVC doses in clonigenic assays. The human cancer cells were synchronised in G1, released into S and treated with UVC or mitomycin C. At 18 h post mitomycin C treatment approximately 6-fold more Fhit-positive than -negative cells had died, and 18 h post UVC treatment 3.5-fold more Fhit-positive cells were dead. Similar results were obtained for the murine -/- cells. After low UVC doses, the rate of DNA synthesis in -/- cells decreased more rapidly and steeply than in +/+ cells, although the Atr-Chk1 pathway appeared intact in both cell types. UVC surviving Fhit -/- cells appear transformed and exhibit >5-fold increased mutation frequency. This increased mutation burden could explain the susceptibility of Fhit-deficient cells in vivo to malignant transformation.
Subject(s)
Acid Anhydride Hydrolases/physiology , Apoptosis , Cell Cycle , Drug Resistance, Neoplasm , Mitomycin/adverse effects , Neoplasm Proteins/physiology , Radiation Tolerance , Stomach Neoplasms/pathology , Acid Anhydride Hydrolases/genetics , Animals , Apoptosis/drug effects , Apoptosis/radiation effects , Ataxia Telangiectasia Mutated Proteins , Cell Cycle/drug effects , Cell Cycle/radiation effects , Cell Cycle Proteins/metabolism , Cell Transformation, Neoplastic/drug effects , Cell Transformation, Neoplastic/radiation effects , Checkpoint Kinase 1 , Colony-Forming Units Assay , DNA/drug effects , DNA/radiation effects , Gene Expression Regulation, Neoplastic , Genes, Tumor Suppressor , Humans , Kidney/drug effects , Kidney/radiation effects , Kinetics , Mice , Mutation/genetics , Neoplasm Proteins/genetics , Protein Kinases/metabolism , Protein Serine-Threonine Kinases/metabolism , Signal Transduction , Stomach Neoplasms/metabolism , Tumor Cells, Cultured , Ultraviolet RaysABSTRACT
Fhit protein has a putative tumor suppressor function in several types of human and experimental cancers. To assess whether Fhit is involved in fetal development we have examined the distribution of Fhit protein in the 12- through 16-day postcoitum mouse fetus and in postnatal day 0 mouse pups by immunocytochemistry. High levels of Fhit protein were observed in the endodermal derivatives, namely, bronchi, trachea, esophagus, stomach, and intestine, in the 12- to 16-day postcoitum mouse fetus and in the postnatal day 0 pup. Other tissues showed a more restricted pattern of Fhit protein expression. These results suggest that Fhit may play a role in the development of specific tissues during mouse development.
Subject(s)
Acid Anhydride Hydrolases , Lung/chemistry , Lung/embryology , Neoplasm Proteins , Proteins/analysis , Proteins/genetics , Animals , Endoderm/chemistry , Gene Expression Regulation, Developmental , Kidney/chemistry , Kidney/embryology , Liver/chemistry , Liver/embryology , Mesoderm/chemistry , Mice , Mice, KnockoutABSTRACT
To investigate the role of the Fhit gene in carcinogen induction of neoplasia, we have inactivated one Fhit allele in mouse embryonic stem cells and produced (129/SvJ x C57BL/6J) F(1) mice with a Fhit allele inactivated (+/-). Fhit +/+ and +/- mice were treated intragastrically with nitrosomethylbenzylamine and observed for 10 wk posttreatment. A total of 25% of the +/+ mice developed adenoma or papilloma of the forestomach, whereas 100% of the +/- mice developed multiple tumors that were a mixture of adenomas, squamous papillomas, invasive carcinomas of the forestomach, as well as tumors of sebaceous glands. The visceral and sebaceous tumors, which lacked Fhit protein, were similar to those characteristic of Muir-Torre familial cancer syndrome.
