Dhh1 regulates the G1/S-checkpoint following DNA damage or BRCA1 expression in yeast.

BACKGROUND: Heterologous expression of the tumor suppressor BRCA1 in the yeast Saccharomyces cerevisiae is lethal. To identify potential new BRCA1-interacting gene targets, we characterized highly conserved ionizing radiation (IR) sensitive gene deletions that suppress BRCA1-induced lethality in yeast. MATERIALS AND METHODS: Previously, we exposed an isogenic collection of yeast strains individually deleted for 4746 nonessential genes to IR and identified 199 radiation sensitive deletion strains. A subset (n = 130) of these were screened for those that suppressed the G1 arrest and lethality observed following galactose-induced expression from a GAL::BRCA1 plasmid in wild type yeast. RESULTS: We found that deletions of two core components of the highly conserved CCR4-NOT transcription complex (CCR4 or DHH1) rescued BRCA1-induced G1 arrest and lethality in yeast. This was not because of down regulation of the GAL promoter since both deletion strains produce large amounts of BRCA1 that is rapidly degraded. In addition, heterologous expression of BRCA1 results in increased transcription of the DNA damage-inducible reporter construct DIN::LacZ. Reduced viability following IR and nitrogen starvation was observed among strains deleted for CCR4 or DHH1 because of a defect in G1 to S phase checkpoint transition. Lethality following nitrogen starvation and IR was partially rescued in dhh1Delta strains by expressing the human ortholog of DHH1 (DDX6) which has been identified as a breakpoint oncogene.T CONCLUSIONS: hese results suggest that BRCA1 may promote genomic stability in human cells by interacting with the highly conserved ortholog of DHH1 (DDX6) to properly activate G1/S checkpoint arrest following DNA damage.

The novel tubulin-binding drug BTO-956 inhibits R3230AC mammary carcinoma growth and angiogenesis in Fischer 344 rats.

BTO-956 [methyl-3,5-diiodo-4-(4'-methoxyphenoxy)benzoate], a novel tubulin-binding drug and thyroid hormone analogue, was originally found to inhibit human carcinoma cell proliferation in vitro and to have potent growth delay activity in human breast and ovarian carcinoma xenografts in nude mice. Here we report that BTO-956 given to Fischer 344 rats also inhibits corneal angiogenesis and the growth and neovascularization of the R3230Ac rat mammary carcinoma tumor implanted in skin-fold window chambers. Hydron pellets containing recombinant human basic fibroblast growth factor (50 ng) and Sucralfate (20 microg) were implanted into surgically created corneal micropockets (day 0). BTO-956 was administrated by oral gavage (500 mg/kg, twice a day for 6 days) on days 1-6 (controls received vehicle alone). On day 7, rats received retrograde infusions of India ink via the thoracic aorta to visualize the corneal vasculature. Digitized images of slide-mounted corneas from control and treated animals were taken with a microscope. For the tumor growth and angiogenesis study, small pieces of R3230Ac tumor from a donor rat were implanted into surgically prepared window chambers (day 0). BTO-956 was given during days 5-11, and images of the tumors and their vasculature were recorded on day 12. No body weight loss was observed in either study. BTO-956 significantly inhibited corneal angiogenesis (by 50-80%), as assessed by measurements of limbal circumference displaying neovascularization, vessel length, vascularized area, and vascular area density. In the window chamber assay, tumors from treated animals were >50% smaller than tumors in control animals. In addition, vascular length densities in peripheral tumor zones were 30% less in treated compared with control animals. Together, these findings demonstrate that BTO-956 can inhibit angiogenesis induced by a growth factor in the rat cornea and in the peripheral area of implanted tumors, where tumor angiogenesis is most active.

Studies of marginal zinc deprivation in rhesus monkeys: infant behavior.

Rhesus monkey infants were marginally deprived of zinc (4 ppm diet) from conception and were compared to controls (100 ppm diet) during the first year of life in development of reflexes and motor patterns, mother-infant interaction, delayed response performance, discrimination learning and reversal, and open field behavior. Deficits in amount and variety of behavior were recorded in deprived infants; spontaneous locomotor activity was 50% below control levels in males at 1 mo of age; spontaneous activity was 7-10% lower in both males and females at 3 mo of age; response latencies were 50% lower than controls at 7-9 mo; failure to reach discrimination reversal criterion was seen in 71% of deprived infants as compared to 10% of controls at 10 mo of age; and abnormally low levels of climbing and exploration were seen in two of six deprived infants at 12 mo of age. No abnormalities in the rate of behavioral development or in emotional adaptability were observed. These and other results suggest that syndromes of lethargy, apathy, and hypoactivity are characteristic of behavioral effects of marginal zinc deprivation in primates.

Studies of marginal zinc deprivation in rhesus monkeys. IV. Growth of infants in the first year.

Growth was evaluated in rhesus monkey infants that were the offspring of females given a marginally zinc-deficient diet (4 micrograms/g zinc) from the beginning of pregnancy and through 12 months of postnatal life. These zinc-deficient (ZD) infants were compared to controls whose mothers were fed a complete diet, either ad libitum or pair-fed to zinc-deficient dams, throughout gestation and lactation. Male ZD infants had evidence of growth retardation at birth. In contrast, growth retardation in female ZD infants was not observed until 1 month of age. From 3 to 9 months of age (late lactation and subsequent to weaning) ZD infants attained weights similar to those of the control group. However, analysis of crown-rump and femur length indicated that ZD infants' growth was less than optimal throughout the entire 1st yr of observation. In addition, skinfold thickness was markedly higher in ZD than in control infants in the postweaning period. In the juvenile period (9-12 months of age) both male and female ZD animals fell behind controls in body weight. ZD juveniles were also hypogeusic, as determined by a quinine acceptance test. Low weight ZD infants had reduced somatic growth as reflected in sitting height, long bone growth, head circumference, and limb circumference. Regression analysis indicated that impaired growth rates from 9 to 12 months were associated with both lower food intake and reduced food use efficiency. Plasma zinc concentration was, in general, inversely related to weight gain in both groups during the 1st yr.