Faculty Publications

We have investigated the molecular mechanisms involved in 17beta-estradiol-induced angiogenic pathway. We show here that 17beta-estradiol promoted a 6-fold increase in Jagged1 expression and an 8-fold increase in Notch1 expression by cDNA arrays in breast cancer MCF7 cells. Interestingly, Jagged1 was abrogated by incubation with the estrogen antagonist, ICI182,780. A similar upregulation of both Notch1 receptor and Jagged1 ligand was found in endothelial cells. Additionally, imperfect estrogen-responsive elements were found in the 5' untranslated region of Notch1 and Jagged1 genes. Treatment with 17beta-estradiol also led to an activation of Notch signaling in MCF7 cells expressing Notch1 reporter gene or by promoting Jagged1-induced Notch signaling in coculture assays. Inoculation of MCF7 cells in 17beta-estradiol-treated nude mice resulted in upregulation of Notch1 expression as well as increased number of tumor microvessels in comparison to placebo-treated mice. Notch1-ex pressing endothelial cell cultures formed cord-like structures on Matrigel in contrast to cells expressing a dominant-negative form of Notch1, emphasizing the relevance of Notch1 pathway in vessel assembly. Finally, Notch1-expressing MCF7 cells upregulated hypoxia-inducible factor 1alpha gene, a well-known angiogenic factor that clustered with Notch1 gene. This study implicates Notch signaling in the cross talk between 17beta-estradiol and angiogenesis.

There is a wide variation in the number of CD34+ cells infused for an autologous transplantation. While the minimum number of hematopoietic stem cells for a successful transplantation has been established, there is no definite information on the optimum number or the maximum number of stem cells. It is generally agreed that a minimum dose of 2.5 x 10(6) CD34+ cells is necessary for successful engraftment. Although engraftment of neutrophils and platelets is achieved at that dose, it is delayed and is also negatively influenced by other factors. Reinfusion of 5.0 x 10(6) CD34+ cells results in prompt engraftment of all three cell lines and should be the preferred target. At least one study indicated that a very large number of cells (>15 x 10(6) CD34+ cells) resulted in further improvement in engraftment, decreased packed red blood cell and platelet transfusion, shorter hospitalization, and overall decreased costs. In contrast, a few studies showed that reinfusion of a large number of CD34+ cells causes fever and engraftment syndrome and may result in prolongation of the inpatient stay. Marrow culture assays performed post-transplant have shown decreased hematopoietic reserve as well as changes in the stromal cells. These changes persist for several years after the transplant. Generally, salvage chemotherapy is poorly tolerated post-transplant due to impaired marrow reserve. This hypothesis has not been validated by systematic clinical studies. It is undetermined if larger doses of stem cells improves the marrow reserve.

To define the prevalence and patterns of self-initiated herbal and vitamin supplementation among men at high risk of developing prostate cancer, as there is increasing public awareness of prostate cancer screening, risk-factor assessment and prevention, leading to increasing interest in the use and systematic study of nutritional therapies for prostate cancer prevention. Since 1996 our institution has prospectively maintained a prostate cancer-risk registry through its Prostate Cancer Risk Assessment Program (PRAP). Eligibility includes African-American men, any man with at least one first-degree relative or two or more second-degree relatives with prostate cancer, or men who tested positively for the BRCA1 gene mutation. A 420-item self-administered questionnaire was completed and included the use of nutritional supplements and complementary therapies. We divided men into groups who used supplements to lessen their cancer risk and those who did not. The prevalence and patterns of use were evaluated and the two groups then compared for differences in demographic, socio-economic and risk-perception variables. In all, 345 high-risk men were enrolled in the PRAP over a 5-year period. Data on the use of dietary or herbal supplements were available on 333 men (97%), of whom over half (170) reported taking one or more supplements to prevent prostate cancer. Supplement use was divided into eight categories, including vitamins, minerals, extracts from fruits/seeds, organic compounds, flowers/bulbs, leaves/bark, roots, or animal products. Most commonly used for self-initiated chemoprevention were vitamins (95%), minerals (28%), and fruit/seed extracts (18%). More than a quarter of men (27%) took three or more agents. Men taking proactive preventative measures were statistically more likely to be Caucasian and aged > 60 years (P < 0.05). African-Americans were less likely to self-initiate preventative steps. Men taking supplements tended to return more often for follow-up and participate in PRAP longer, while those not taking supplements tended to earn less and report less self-perceived ! risk. A significant proportion of men at risk of developing prostate cancer initiate measures they perceive to reduce their risk. Although the chemopreventative efficacy of many of these supplements remains unsubstantiated, they are widely perceived by the public to reduce the risk of developing prostate cancer. These data provide an insight into patient perceptions and misconceptions of chemopreventative strategies, and may help to refine recruitment efforts in multi-institutional prostate cancer prevention trials.

A review on anticancer therapeutic regimens such as chemo-, radiation- and immunotherapy, and cancer-cell resistance to apoptosis. The resistance of tumor cells to anticancer therapies may result from a failure to activate apoptotic pathways in response to drug treatment. A better understanding of the mol. mechanisms of cell death in response to these anticancer therapeutic strategies will help to avoid ineffective treatment regimens and provide a mol. basis for the new therapeutic modalities targeting apoptosis-resistant forms of cancer. [on SciFinder (R)]

The two-hybrid system is an artificially constructed genetic system intended to facilitate the detection and assessment of protein-protein interactions. In the two-hybrid system a host organism, typically yeast or bacteria, is so engineered as to contain three components. These are a first protein fused to a DNA-binding domain of known specificity (hybrid 1); a second protein fused to a transcriptional activation domain (hybrid 2), that can interact with the first protein, constituting a functional, albeit composite, transcription factor; and one or more reporter genes transcribed based on the binding of the composite transcription factor. Many permutations of the two-hybrid paradigm have been developed, and two-hybrid systems have become a mainstay of proteomic investigations. [on SciFinder (R)]

Extracellular ATP is released from activated platelets and endothelial cells and stimulates proliferation of vascular smooth muscle cells (VSMC). We found that ATP stimulates a profound but transient activation of protein kinase A (PKA) via purinergic P2Y receptors. The specific inhibition of PKA by adenovirus-mediated transduction of the PKA inhibitor (PKI) attenuates VSMC proliferation in response to ATP, suggesting a positive role for transient PKA activation in VSMC proliferation. By contrast, isoproterenol and forskolin, which stimulate a more sustained PKA activation, inhibit VSMC growth as expected. On the other hand, the activity of serum response factor (SRF) and the SRF-dependent expression of smooth muscle (SM) genes, such as SM-alpha-actin and SM22, are extremely sensitive to regulation by PKA, and even transient PKA activation by ATP is sufficient for their downregulation. Analysis of the dose responses of PKA activation, VSMC proliferation, SRF activity, and SM gene expression to ATP, with or without PKI overexpression, suggests the following model for the phenotypic modulation of VSMC by ATP, in which the transient PKA activation plays a critical role. At low micromolar doses, ATP elicits a negligible effect on DNA synthesis but induces profound SRF activity and SM gene expression, thus promoting the contractile VSMC phenotype. At high micromolar doses, ATP inhibits SRF activity and SM gene expression and promotes VSMC growth in a manner dependent on transient PKA activation. Transformation of VSMC by high doses of ATP can be prevented and even reversed by inhibition of PKA activity.