0 -Methoxy-3,4 0 ,5,7-tetrahydroxyflavone (isorhamnetin) is a plant flavonoid that occurs in fruits and medicinal herbs. Isorhamnetin exerts anticancer effects, but the underlying molecular mechanism for the chemopreventive potential of isorhamnetin remains unknown. Here, we report anti-skin cancer effects of isorhamnetin, which inhibited epidermal growth factor (EGF)-induced neoplastic cell transformation. It also suppressed anchorage-dependent and -independent growth of A431 human epithelial carcinoma cells. Isorhamnetin attenuated EGF-induced COX-2 expression in JB6 and A431 cells. In an in vivo mouse xenograft using A431 cells, isorhamnetin reduced tumor growth and COX-2 expression. The EGF-induced phosphorylation of extracellular signal-regulated kinases, p90 and p70 ribosomal S6 kinases, and Akt was suppressed by isorhamnetin. In vitro and ex vivo kinase assay data showed that isorhamnetin inhibited the kinase activity of MAP (mitogen-activated protein)/ERK (extracellular signal regulated kinase) kinase (MEK) 1 and PI3-K (phosphoinositide 3-kinase) and the inhibition was due to direct binding with isorhamnetin. Notably, isorhamnetin bound directly to MEK1 in an ATP-noncompetitive manner and to PI3-K in an ATP-competitive manner. This report is the first mechanistic study identifying a clear molecular target for the anticancer activity of isorhamnetin. Overall, these results indicate that isorhamnetin has potent anticancer activity and it primarily targets MEK and PI3-K, which might contribute to the chemopreventive potential of certain foods. Cancer Prev Res; 4(4); 582-91. Ó2011 AACR.

Ultraviolet (UV) irradiation is the most important factor contributing to the development of skin cancer. The use of chemopreventive agents, especially naturally occurring plant products, to prevent skin cancer caused by UV might an effective therapeutic or preventive intervention. Using in silico virtual screening of the Chinese Medicine Library, we identified norathyriol as a potential ERK2 inhibitor. Norathyriol is a metabolite of mangiferin, which is found in mango, Hypericum elegans, and Tripterospermum lanceolatum, and has potent anticancer-promoting activity. Here, we show that norathyriol inhibits ERK1/2 kinase activities and attenuates UVB-induced phosphorylation of the mitogen-activated protein kinase (MAPK) cascades. Direct binding of norathyriol with ERK2 was confirmed by a co-crystal structure. The norathyriol xanthone moiety acts as an adenine mimeric and anchors the compound by hydrogen bonds to the hinge region of the protein ATP-binding site. Norathyriol inhibited cell growth in mouse skin epidermal JB6 P+ cells by inducing G2-M phase arrest. Mouse skin tumorigenesis data clearly showed that treatment with norathyriol significantly suppressed solar UV-induced skin carcinogenesis in vivo. Results also indicated that norathyriol exhibits a potent chemopreventive activity through the inhibition of transcription factor AP-1 and NF-κB by targeting ERKs in UV-induced skin carcinogenesis.

Target cell proliferation was investigated throughout the development of esophageal cancer induced by N-nitroso-methylbenzylamine (NMBA) in weanling rats maintained on zinc-deficient or sufficient diets. Deficient rats were fed ad libitum, while zinc-sufficient rats were either pair-fed to the deficient animals or fed ad libitum. After 5 weeks, half of the animals in each dietary group were given six intragastric doses of NMBA (2 mg/kg; twice weekly). The remaining rats were untreated by carcinogen. At weeks 1, 2, 3, 4, 5, 7, 9 and 11 post first dose, esophageal cell proliferation was assessed in rats from each group by in vivo bromodeoxyuridine (BrDU) labeling followed by immunohistochemical detection of cells in S-phase. At 11 weeks, the tumor incidence was 100, 23 and 6%, respectively, in the zinc-deficient, zinc-sufficient, ad libitum and pair-fed groups. In vivo BrDU labeling revealed that in the NMBA-untreated groups, the labeling index (LI), the number of labeled cells, and the total number of cells per cross section of entire esophagi were significantly increased by zinc deficiency at all time points; LI was lowest in zinc-sufficient, pair-fed rats. During NMBA treatment (weeks 6, 7 and 8), increased cell proliferation occurred in both groups of zinc-sufficient esophagi but only during week 6 in the deficient ones. In the weeks following the cessation of NMBA treatment, zinc-deficient esophagi showed significantly increased LI and greater number of labeled cells than the carcinogen treated, zinc-sufficient pair-fed or ad libitum fed groups. On the other hand, NMBA-treated zinc-sufficient pair-fed rats showed lower LI and smaller number of labeled cells than their zinc-sufficient ad libitum counterparts. Most importantly, esophageal papillomas were found in two zinc-deficient animals that had received no NMBA treatment, after 10-11 weeks of experimental diet. These data support a direct relationship between cell proliferation and tumor incidence, and also provide evidence that zinc deficiency and its associated cell proliferation could be carcinogenic.

The activation of cellular signal transduction pathways by solar ultraviolet (SUV) irradiation plays a vital role in skin tumorigenesis. Although many pathways have been studied using pure ultraviolet A (UVA) or ultraviolet B (UVB) irradiation, the signaling pathways induced by SUV (i.e., sunlight) are not understood well enough to permit improvements for prevention, prognosis and treatment. Here we report parallel protein kinase array studies aimed at determining the dominant signaling pathway involved in SUV irradiation. Our results indicated that the p38-related signal transduction pathway was dramatically affected by SUV irradiation. SUV (60 kJ UVA/m2/3.6 kJ UVB/m2) irradiation stimulates phosphorylation of p38α (MAPK14) by 5.78-fold, MSK2 (RPS6KA4) by 6.38-fold and HSP27 (HSPB1) by 34.56-fold compared to untreated controls. By investigating the tumorigenic role of SUV-induced signal transduction in wildtype and p38 dominant negative (p38 DN) mice, we found that p38 blockade yielded fewer and smaller tumors. These results establish that p38 signaling is critical for SUV-induced skin carcinogenesis.

Lapatinib, an oral, small-molecule, reversible inhibitor of both EGFR and HER2, is highly active in HER2 positive breast cancer as a single agent and in combination with other therapeutics. However, resistance against lapatinib is an unresolved problem in clinical oncology. Recently, interest in the use of natural compounds to prevent or treat cancers has gained increasing interest because of presumed low toxicity. Quercetin-3-methyl ether, a naturally occurring compound present in various plants, has potent anticancer activity. Here, we found that quercetin-3-methyl ether caused in a significant growth inhibition of lapatinib-sensitive and -resistant breast cancer cells. Western blot data showed that quercetin-3-methyl ether had no effect on Akt or ERKs signaling in resistant cells. However, quercetin-3-methyl ether caused a pronounced G2/M block mainly through the Chk1-Cdc25c-cyclin B1/Cdk1 pathway in lapatinib-sensitive and -resistant cells. In contrast, lapatinib produced an accumulation of cells in the G1 phase mediated through cyclin D1, but only in lapatinib-sensitive cells. Moreover, quercetin-3-methyl ether induced significant apoptosis, accompanied with increased levels of cleaved caspase 3, caspase 7 and poly (ADP-ribose) polymerase (PARP) in both cell lines. Overall, these results suggested that quercetin-3-methyl ether might be a novel and promising therapeutic agent in lapatinib-sensitive or -resistant breast cancer patients.

The Tianlai Dish Pathfinder Array is a radio interferometer designed to test techniques for 21 cm intensity mapping in the post-reionization universe as a means for measuring large-scale cosmic structure. It performs drift scans of the sky at constant declination. We describe the design, calibration, noise level, and stability of this instrument based on the analysis of about $\sim 5 {{\ \rm per\ cent}}$ of 6,200 hours of on-sky observations through October, 2019. Beam pattern determinations using drones and the transit of bright sources are in good agreement, and compatible with electromagnetic simulations. Combining all the baselines, we make maps around bright sources and show that the array behaves as expected. A few hundred hours of observations at different declinations have been used to study the array geometry and pointing imperfections, as well as the instrument noise behaviour. We show that the system temperature is below 80 K for most feed antennas, and that noise fluctuations decrease as expected with integration time, at least up to a few hundred seconds. Analysis of long integrations, from 10 nights of observations of the North Celestial Pole, yielded visibilities with amplitudes of 20-30 mK, consistent with the expected signal from the NCP radio sky with <10 mK precision for 1 MHz × 1 min binning. Hi-pass filtering the spectra to remove smooth spectrum signal yields a residual consistent with zero signal at the 0.5 mK level.

BackgroundDiabetic nephropathy (DN) is a common complication of diabetes, caused by diabetic microvascular lesions. The pathogenesis of DN is complicated, involving genetics, physics, chemistry, and environmental factors. Chemerin is a fat cell factor that participates in regulating inflammation. Vascular endothelial growth factor (VEGF) promotes vascular endothelial cell proliferation, differentiation, and angiogenesis. The relationship role of Chemerin and VEGF in DN is not fully understood.Material/MethodsSD rats were randomly divided into 2 groups: the control group and the DN group. Streptozotocin was used to construct the DN model. Serum creatinine (Scr), blood urea nitrogen (BUN), and urine microalbumin (UAlb) were detected. Real-time PCR and Western blot were used to test Chemerin and VEGF mRNA and protein expression in kidney tissue. ELISA was performed to test TGF-β1, TNF-α, and INF-γ levels. The correlation of Chemerin and VEGF with renal function and inflammatory factors was analyzed.ResultsDN group rats showed obviously increased Scr and BUN levels, and elevated TGF-β1, TNF-α, and INF-γ secretion (P<0.05). Compared with controls, Chemerin and VEGF were clearly overexpressed in the DN group (P<0.05). Chemerin and VEGF expression were positively correlated with inflammatory factors and renal function.ConclusionsChemerin and VEGF play important roles in DN by regulating inflammatory factors and renal function. They may be treated as indicators of DN.

Activation of receptor tyrosine kinases (RTK) plays a key role in the prognosis of mammary cancer. Lapatinib is a small molecule dual RTK inhibitor that targets epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2). Identifying the protein targets involved in the effects of lapatinib and other RTK inhibitors might help determine why preventive efficacy varies. In this study, female Sprague-Dawley rats were given methylnitrosourea (MNU) by intravenous injection resulting in the development of multiple estrogen receptor-positive tumors. Treatment with lapatinib beginning 5 days after MNU was highly effective in preventing cancer development. In addition, we treated rats with palpable mammary tumors with lapatinib daily. In these tumor-bearing animals, treatment continued for 42 days and therapeutic results were obtained. Some rats bearing cancers were treated for 5 days, and the resulting lesions were examined for biomarker modulation. Lapatinib effectively suppressed the abundance of HER2, phosphorylated HER2 (Tyr1221/1222), and phosphorylated EGFR (Tyr1173, Tyr1110) compared with tumors from untreated rats. Protein array analyses allowed parallel determination of the effect of lapatinib on the relative levels of protein phosphorylation and proteins associated with apoptosis. These results combined with immunoreactivity data indicated that, in addition to EGFR and HER2, lapatinib treatment was associated with changes in a number of other signaling molecules, including IGF-1R, Akt, and downstream targets such as GSK3, p27, p53, and cyclin D1 presumably leading to impaired proliferation, apoptosis, or cell-cycle arrest.