Beta-lapachone (beta-Lap; 3,4-dihydro-2, 2-dimethyl-2H-naphthol[1, 2-b]pyran-5,6-dione) is a novel anti-cancer drug under phase I/II clinical trials. beta-Lap has been demonstrated to cause apoptotic and necrotic death in a variety of human cancer cells in vitro and in vivo. The mechanisms underlying the beta-Lap toxicity against cancer cells has been controversial. The most recent view is that beta-Lap, which is a quinone compound, undergoes two-electron reduction to hydroquinone form utilizing NAD(P)H or NADH as electron source. This two-electron reduction of beta-Lap is mediated by NAD(P)H:quinone oxidoreductase (NQO1), which is known to mediate the reduction of many quinone compounds. The hydroquinone forms of beta-Lap then spontaneously oxidizes back to the original oxidized beta-Lap, creating futile cycling between the oxidized and reduced forms of beta-Lap. It is proposed that the futile recycling between oxidized and reduced forms of beta-Lap leads to two distinct cell death pathways. First one is that the two-electron reduced beta-Lap is converted first to one-electron reduced beta-Lap, i.e., semiquinone beta-Lap (SQ).- causing production of reactive oxygen species (ROS), which then causes apoptotic cell death. The second mechanism is that severe depletion of NAD(P)H and NADH as a result of futile cycling between the quinone and hydroquinone forms of beta-Lap causes severe disturbance in cellular metabolism leading to apoptosis and necrosis. The relative importance of the aforementioned two mechanisms, i.e., generation of ROS or depletion of NAD(P)H/NADH, may vary depending on cell type and environment. Importantly, the NQO1 level in cancer cells has been found to be higher than that in normal cells indicating that beta-Lap may be preferentially toxic to cancer cells relative to non-cancer cells. The cellular level of NQO1 has been found to be significantly increased by divergent physical and chemical stresses including ionizing radiation. Recent reports clearly demonstrated that beta-Lap and ionizing radiation kill cancer cells in a synergistic manner. Indications are that irradiation of cancer cells causes long-lasting elevation of NQO1, thereby sensitizing the cells to beta-Lap. In addition, beta-Lap has been shown to inhibit the repair of sublethal radiation damage. Treating experimental tumors growing in the legs of mice with irradiation and intraperitoneal injection of beta-Lap suppressed the growth of the tumors in a manner more than additive. Collectively, beta-Lap is a potentially useful anti-cancer drug, particularly in combination with radiotherapy.
Animals ; Apoptosis ; Benzoquinones ; Cell Death ; Electrons ; Humans ; Hydroquinones ; Injections, Intraperitoneal ; Leg ; Mice ; NAD ; Naphthoquinones ; Necrosis ; Radiation Tolerance ; Radiation, Ionizing ; Reactive Oxygen Species ; Recycling ; Substrate Cycling

Existence of Y derived chromosome in Turner patients is significant due to the risk of gonadoblastoma development, but cytogenetic analysis may fail to detect low levels of Y chromosomal materials. Recent studies using PCR based methods showed higher sensitivity to detect Y-specific sequences, in patients who were Y chromosome-negative cytogenetically. In this study PCR was performed on 44 Turner patients with no Y chromosome by cytogenetic analysis to detect the SRY, AMELY, ZFY, and DYZ1 sequences. Of seven patients whose karyotypes were 45,X/46,X,+mar, three patients were positive for SRY, ZFY, and AMELY. DYZ1 sequences was negative in them. And any of SRY, ZFY, AMELY, and DYZ1 sequences was detected in the remaining 37 patients. This result shows that PCR analysis for Y-specific sequences in Turner patients, especially in patients who have marker chromosome is a significant effort.
Cytogenetic Analysis ; Genes, sry ; Gonadoblastoma ; Humans ; Karyotype ; Polymerase Chain Reaction ; Turner Syndrome* ; Y Chromosome

beta-Carotene has shown antioxidant and antiinflammatory activities; however, its molecular mechanism has not been clearly defined. We examined in vitro and in vivo regulatory function of beta-carotene on the production of nitric oxide (NO) and PGE2 as well as expression of inducible NO synthase (iNOS), cyclooxygenase-2, TNF-alpha, and IL-1beta. beta-Carotene inhibited the expression and production of these inflammatory mediators in both LPSstimulated RAW264.7 cells and primary macrophages in a dose-dependent fashion as well as in LPS-administrated mice. Furthermore, this compound suppressed NF-kappaB activation and iNOS promoter activity in RAW264.7 cells stimulated with LPS. beta-Carotene blocked nuclear translocation of NF-kappaB p65 subunit, which correlated with its inhibitory effect on IkappaBalpha phosphorylation and degradation. This compound directly blocked the intracellular accumulation of reactive oxygen species in RAW264.7 cells stimulated with LPS as both the NADPH oxidase inhibitor diphenylene iodonium and antioxidant pyrrolidine dithiocarbamate did. The inhibition of NADPH oxidase also inhibited NO production, iNOS expression, and iNOS promoter activity. These results suggest that beta-carotene possesses anti-inflammatory activity by functioning as a potential inhibitor for redox-based NF-kappaB activation, probably due to its antioxidant activity.
Animals ; Anti-Inflammatory Agents/*pharmacology ; Antioxidants/*pharmacology ; Dinoprostone/metabolism ; Female ; Gene Expression/drug effects ; Inflammation Mediators/*metabolism ; Lipopolysaccharides/pharmacology ; Macrophages/*drug effects ; Mice ; Mice, Inbred BALB C ; NF-kappa B/*antagonists & inhibitors/genetics/metabolism ; Nitric Oxide/metabolism ; Oxidation-Reduction ; Research Support, Non-U.S. Gov't ; beta Carotene/*pharmacology