Rachel Davis

Inhibitors of VEGF signaling can block angiogenesis and reduce tumor vascularity, but little is known about the reversibility of these changes after treatment ends. In the present study, regrowth of blood vessels in spontaneous RIP-Tag2 tumors and implanted Lewis lung carcinomas in mice was assessed after inhibition of VEGF receptor signaling by AG-013736 or AG-028262 for 7 days. Both agents caused loss of 50%-60% of tumor vasculature. Empty sleeves of basement membrane were left behind. Pericytes also survived but had less alpha-SMA immunoreactivity. One day after drug withdrawal, endothelial sprouts grew into empty sleeves of basement membrane. Vessel patency and connection to the bloodstream followed close behind. By 7 days, tumors were fully revascularized, and the pericyte phenotype returned to baseline. Importantly, the regrown vasculature regressed as much during a second treatment as it did in the first. Inhibition of MMPs or targeting of type IV collagen cryptic sites by antibody HUIV26 did not eliminate the sleeves or slow revascularization. These results suggest that empty sleeves of basement membrane and accompanying pericytes provide a scaffold for rapid revascularization of tumors after removal of anti-VEGF therapy and highlight their importance as potential targets in cancer therapy.

Unlike during development, blood vessels in the adult are generally thought not to require VEGF for normal function. However, VEGF is a survival factor for many tumor vessels, and there are clues that some normal blood vessels may also depend on VEGF. In this study, we sought to identify which, if any, vascular beds in adult mice depend on VEGF for survival. Mice were treated with a small-molecule VEGF receptor (VEGFR) tyrosine kinase inhibitor or soluble VEGFRs for 1-3 wk. Blood vessels were assessed using immunohistochemistry or scanning or transmission electron microscopy. In a study of 17 normal organs after VEGF inhibition, we found significant capillary regression in pancreatic islets, thyroid, adrenal cortex, pituitary, choroid plexus, small-intestinal villi, and epididymal adipose tissue. The amount of regression was dose dependent and varied from organ to organ, with a maximum of 68% in thyroid, but was less in normal organs than in tumors in RIP-Tag2-transgenic mice or in Lewis lung carcinoma. VEGF-dependent capillaries were fenestrated, expressed high levels of both VEGFR-2 and VEGFR-3, and had normal pericyte coverage. Surviving capillaries in affected organs had fewer fenestrations and less VEGFR expression. All mice appeared healthy, but distinct physiological changes, including more efficient blood glucose handling, accompanied some regimens of VEGF inhibition. Strikingly, most capillaries in the thyroid grew back within 2 wk after cessation of treatment for 1 wk. Our findings of VEGF dependency of normal fenestrated capillaries and rapid regrowth after regression demonstrate the plasticity of the adult microvasculature.

OBJECTIVE: To estimate the effect of maternal cigarette smoking on birth weight, crown-heel length, and ten other neonatal anthropometric measurements. METHODS: Data are from a cohort study on risk factors for fetal growth retardation (FGR) in multiparous women conducted from December 1985 through October 1988. Information on smoking status was collected four times during pregnancy. Data analysis included 1205 singleton infants of women delivering at term. Neonatal anthropometric measurements were obtained within 48 hours of birth, including birth weight, crown-heel length, ponderal index, head and abdominal circumferences, arm length and circumference, femur length and thigh circumference, and triceps, thigh, and subscapular skinfold measurements. Analysis of covariance models were used to assess the independent effect of smoking on each neonatal measurement. RESULTS: Neonates born to women who reported smoking during the first trimester had a 0.6-1.9% reduction in most neonatal anthropometric measurements, resulting in an overall reduction of birth weight of 130 g (4%). Neonates born to women who continued to smoke throughout pregnancy had an average adjusted reduction in birth weight of 189 g (5.9%), compared with a 55 g (1.7%) reduction for neonates born to women who stopped smoking after the first trimester. For women who continued to smoke throughout pregnancy, an increased number of cigarettes smoked was associated with increased reductions in birth weight and neonatal chest and abdominal circumferences. For women who stopped smoking after the first trimester, stopping was a better predictor of neonatal anthropometric measurements than the number of cigarettes smoked early in pregnancy. CONCLUSIONS: Except for the ponderal index, all neonatal anthropometric measurements studied showed some negative effect of maternal cigarette smoking. Head circumference is the measurement least reduced. Smoking cessation is a better predictor of infant size than the number of cigarettes smoked in the first trimester.

OBJECTIVE: To compare the prognostic values of unexplained elevated amniotic fluid alpha-fetoprotein (AF AFP > or = 2.0 multiples of the median [MoM]) and unexplained elevated maternal serum alpha-fetoprotein (MSAFP > or = 2.5 MoM). METHODS: We accessed a data base containing the results of MSAFP screening tests, genetic amniocenteses, and pregnancy outcome data on all women undergoing second-trimester genetic amniocentesis from October 1988 through August 1994. After excluding all patients whose elevated AFP levels had any identifiable cause (positive AF acetylcholinesterase, AF blood contamination, fetal malformation or aneuploidy, multiple gestation, etc), 5743 cases were analyzed. Relative risks (RR) for selected pregnancy complications were determined. RESULTS: Elevated MSAFP, with any AF AFP, was associated with fetal growth restriction (RR 2.5, 95% confidence interval [CI] 1.4-4.4), stillbirth (RR 3.5, 95% CI 1.4-8.3), preeclampsia (RR 2.8, 95% CI 1.1-7.0), and preterm delivery (RR 2.8, 95% CI 2.3-3.4). Elevated AF AFP, with any MSAFP, was associated with preeclampsia (RR 4.4, 95% CI 2.0-10.0) and preterm delivery (RR 1.7, 95% CI 1.3-2.4). Elevation of both AF AFP and MSAFP was associated with preterm delivery (RR 4.0, 95% CI 2.8-5.7). When elevated AF AFP was found in association with a normal MSAFP, the RR to develop preeclampsia was 4.6 (95% CI 1.9-11.2). CONCLUSION: Maternal serum alpha-fetoprotein is a better predictor of late pregnancy complications than AF AFP. However, unexplained elevated AF AFP appears to be especially predictive of preeclampsia.

The purpose of this study was to examine whether histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA; Zolinza/vorinostat) could sensitize tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-resistant breast carcinoma in vivo. BALB/c nude mice were orthotopically implanted with TRAIL-resistant MDA-MB-468 cells and treated i.v. with SAHA, TRAIL, or SAHA followed by TRAIL for four times during first 3 weeks. The effects of drugs on tumor growth and markers of apoptosis, metastasis, and angiogenesis were examined. SAHA sensitized TRAIL-resistant xenografts to undergo apoptosis through multiple mechanisms. Whereas TRAIL alone was ineffective, SAHA inhibited growth of MDA-MB-468 xenografts in nude mice by inhibiting markers of tumor cell proliferation, angiogenesis, and metastasis and inducing cell cycle arrest and apoptosis. The sequential treatment of nude mice with SAHA followed by TRAIL was more effective in inhibiting tumor growth, angiogenesis, and metastasis and inducing apoptosis than SAHA alone, without overt toxicity. Treatment of nude mice with SAHA resulted in down-regulation of nuclear factor-kappaB and its gene products (cyclin D1, Bcl-2, Bcl-X(L), vascular endothelial growth factor, hypoxia-inducible factor-1alpha, interleukin-6, interleukin-8, matrix metalloproteinase-2, and matrix metalloproteinase-9) and up-regulation of DR4, DR5, Bak, Bax, Bim, Noxa, PUMA, p21(CIP1), tissue inhibitor of metalloproteinase-1, and tissue inhibitor of metalloproteinase-2 in tumor cells. Furthermore, control mice showing increased rate of tumor growth had increased numbers of CD31(+) or von Willebrand factor-positive blood vessels and increased circulating vascular endothelial growth factor receptor 2-positive endothelial cells compared with SAHA-treated or SAHA plus TRAIL-treated mice. In conclusion, sequential treatment with SAHA followed by TRAIL may target multiple pathways in tumor progression, angiogenesis, and metastasis and represents a novel therapeutic approach to treat breast cancer.