Jui-Chang Chen

THE AQUEOUS PORE THROUGH THE TRANSLOCON HAS A DIAMETER OF 40-60 A DURING COTRANSLATIONAL PROTEIN TRANSLOCATION AT THE ER MEMBRANE

Eukaryotic secretory proteins are cotranslationally translocated through the endoplasmic reticulum (ER) membrane via aqueous pores that span the lipid bilayer. Fluorescent probes were incorporated into nascent secretory proteins using modified Lys-tRNAs, and the resulting nascent chains were sealed off from the cytosol in fully assembled translocation intermediates. Fluorescence quenching agents of different sizes were then introduced into the ER lumen in order to determine which were small enough to enter the pore and to quench the fluorescence of probes inside the ribosome and/or the pore. These accessibility studies showed that the aqueous pore in a functioning translocon is 40-60 A in diameter, making it the largest hole observed to date in a membrane that must maintain a permeability barrier.

Abnormal expression of Period 1 (PER1) in endometrial carcinoma

The development of endometrial carcinoma (EC) is a multiple‐step process, which includes inactivation of tumour suppressor genes, activation of oncogenes, and disturbance of cancer‐related genes. Recent studies have shown that the circadian cycle may influence cancer development and prognosis. In this study, the expression of a circadian gene, PER1, was examined in 35 ECs and paired non‐tumour tissues by real‐time quantitative reverse transcription‐polymerase chain reaction (RT‐PCR) and immunohistochemistry. Expression levels of PER1 were significantly decreased in EC, and mutational analysis of the coding regions, together with methylation analysis of cytosine‐phosphate guanosine (CpG) sites in the promoter area, was performed to investigate the possible mechanisms. The analyses detected four single nucleotide polymorphisms in both tumour and non‐tumour tissues, which had no relationship with the expression of PER1. In the promoter area of the PER1 gene, the CpG sites were methylated in 31.4% of ECs, but in 11.4% of paired non‐tumour tissues (p < 0.05). These results suggest that the down‐regulation of PER1 expression in EC was partly due to inactivation of the PER1 gene by DNA methylation of the promoter and partly due to other factors. Analysis of the relationships between the expression of PER1, P53, c‐MYC, cyclin A, cyclin B, and cyclin D1 showed no definite relationship. These results suggest that down‐regulation of the PER1 gene disrupts the circadian rhythm, which may favour the survival of endometrial cancer cells. Copyright

Promoter methylation in circadian genes of endometrial cancers detected by methylation-specific PCR

Methylation of CpG dinucleotides in the promoter sequence of a gene can lead to deregulated and suppressed gene expression. In this study, we have developed procedures for methylation‐specific polymerase chain reaction (MSP) and sequencing analysis to determine CpG methylation status of the promoter sequences of nine circadian genes in 35 endometrial cancers (EC) and paired noncancerous endometrial tissues. DNA methylation was found in the promoter sequences of PER1, PER2, and CRY1, but not of other six circadian genes in the ECs and normal tissues examined. Eleven of the 35 EC tissues showed CpG methylation in the promoter sequences of PER1, PER2, or CRY1. Of these 11 cases, 1 had promoter methylation in all the three genes, 1 in PER1 and PER2, 3 in PER1 and CRY1, and 6 in PER1, respectively. In comparison, promoter CpG methylation of PER1, PER2, or CRY1 was found in only 7 of 35 paired noncancerous tissues including 2 in PER1 and PER2, 2 in PER1, and 3 in CRY1. In summary, promoter methylation in the PER1, PER2, or CRY1 circadian genes was detected in about one‐third of EC and one‐fifth of noncancerous endometrial tissues of 35 paired specimens indicating possible disruption of the circadian clock in the development of EC.

CYP3A5* 1 is an Inhibitory Factor for Lung Cancer in Taiwanese

The expression of the cytochrome P450 CYP3A5 enzymes shows a wide variation across the general population and ethnic groups. This wide disparity implies interracial differences in drug clearance and susceptibility to diseases such as cancer. CYP3A5 polymorphisms were rapidly determined using polymerase chain reaction‐restriction fragment length polymorphism analysis in 113 Taiwanese patients with hepatoma, 70 with cervical cancer, 92 with breast cancer, 82 with oral cancer, 90 with thyroid cancer, 133 with lung cancer, and 270 healthy controls. The allelic frequencies of CYP3A5*1 were 25% in hepatoma patients, 33% in cervical cancer patients, 31% in breast cancer patients, 22% in oral cancer patients, 23% in thyroid cancer patients, 20% in lung cancer patients, and 27% in healthy subjects. Lung cancer patients had a significantly lower frequency (20%) of CYP3A5*1 expression than healthy controls (p = 0.028, odds ratio = 1.49, 95% confidence interval = 1.04‐2.13), but there was no statistically significant difference between healthy controls and other cancers. We suggest that CYP3A5*1 may play an important role in individual predisposition to lung cancer in Taiwan.

Effect of Temperature on the Growth of Silver Nanoparticles Using Plasmon-Mediated Method under the Irradiation of Green LEDs

Plasmon-mediated shape conversion of spherical silver nanoparticles (NPs) to nanostructures with other shapes under the irradiation of green LEDs (520 ± 20 nm, 35 mw/cm2) at various temperatures (60, 40, 20, 10, 5, and 0 °C) was performed in this study. It was found that the bath temperature used in the reaction can influence the reaction rates, i.e., the times needed for the shape transformation process were 5, 11.5, 25, 45, 72, and 100 h at 60, 40, 20, 10, 5, and 0 °C, respectively. In addition, the bath temperature can also alter the morphologies of the final products. The major products are silver nanoplates at 60, 40 and 20 °C. However, they became decahedral silver NPs at 5 and 0 °C. The percentages of decahedral silver NPs synthesized at 60, 40, 20, 10, 5, and 0 °C are 0%, 1%, 5%, 45%, 73%, and 89%, respectively. Measuring the surface-enhanced Raman spectroscopy (SERS) spectra of the probe molecule R6G in the presence of KBr showed that both silver nanoplate colloids synthesized at 60 °C and decahedral silver NP colloids synthesized at 0 °C in the absence of PVP had good SERS activities.

SARS-CoV infection was from at least two origins in the Taiwan area

Objective: Severe acute respiratory syndrome (SARS) is caused by a new coronavirus. Genomic sequence analysis will provide the molecular epidemiology and help to develop vaccines. Methods: We developed a rapid method to amplify and sequence the whole SARS-CoV genome from clinical specimens. The technique employed one-step multiplex RT-PCR to amplify the whole SARS-CoV genome, and then nested PCR was performed to amplify a 2-kb region separately. The PCR products were sequenced. Results: We sequenced the genomes of SARS-CoV from 3 clinical specimens obtained in Taiwan. The sequences were similar to those reported by other groups, except that 17 single nucleotide variations and two 2-nucleotide deletions, and a 1-nucleotide deletion were found. All the variations in the clinical specimens did not alter the amino acid sequence. Of these 17 sequenced variants, two loci (positions 26203 and 27812) were segregated together as a specific genotype – T:T or C:C. Phylogenetic analysis showed two major clusters of SARS patients in Taiwan. Conclusion: We developed a very economical and rapid method to sequence the whole genome of SARS-CoV, which can avoid cultural influence. From our results, SARS patients in Taiwan may be infected from two different origins.

TCH1036, a indeno[1,2-c]quinoline derivative, potentially inhibited the growth of human brain malignant glioma (GBM) 8401 cells via suppression of the expression of Suv39h1 and PARP

A newly synthesized Indeno[1,2-c]quinoline derivative, which has previously been found to potentially trap DNA-topoisomerase cleavage complexes more effectively than camptothecin, could effectively inhibit the proliferation of a variety of cancers, such as breast cancer treated with TCH1030. In this study, we further explore the activity of the TCH1036, TCH1259 and TCH1030 compounds in suppressing the growth of human brain malignant glioma (GBM) 8401 cells, in addition to elucidating the related mechanisms. According to tests of cytotoxicity, the GBM cells were more sensitive to the inhibitory effects of the TCH1036 compound than to those of the other two compounds. Moreover, the accumulation of GBM cells in the sub-G1 and G2/M phases was clearly induced by the TCH1036 compound in a dose-dependent manner. A screening of the majority of histone-modifier enzymes indicated that the expression of Suv39h1 in the GBM cells was attenuated by treatment with each of the TCH compounds, an observation which was further confirmed by Western blotting. The increase in active-form caspase 3 in the GBM cells treated with TCH compounds caused a high degree of poly (ADP-ribose) polymerase (PARP) cleavage and also enhanced the high ratio of hypodiploid GBM cells in the sub-G1 phase. In molecular docking simulations, it was observed that the stable forms of the TCH compounds could successfully insert into the catalytic pocket of PARP, with the highest affinity being between PARP and the TCH1036 compound. These findings suggested that the TCH1036 compound would be a promising compound in the treatment of brain malignant glioma.

Sulfotransferase lAl is a Risk Factor for Breast Cancer in Young Women

Objectives. SULT1A1, the major form of cytosolic sulfotransferase enzymes (SULTs), activates or metabolizes many chemicals and carcinogens. The effect of the SULT1A1 genotype on the development of cancers is still not clear. The purpose of this study was to analyze the relationship between SULT1A1 polymorphisms and cancer risk. Methods. We determined SULT1A1 polymorphisms by PCR-RFLP and then analyzed the frequencies of the SULT1A1*1 and SULT1A1*2 alleles from several cancerous cohorts. Results. After analyzing 76 hepatoma patients, 180 breast cancer patients, 61 lung cancer patients, 52 oral cancer patients and 74 gastric cancer patients, the frequencies of SULT1A1*1 were 96.1%,94.2%,95.1%,96.1%,and 97.3%, respectively, whereas the frequencies of SULT1A1*2 were 3.9%, 5.8%, 4.9%, 3.9%, and 2.7% respectively. No SULT1A1*3 alleles were found in these patients. Conclusions. In comparison with the frequencies of SULT1A1*1 and SULT1A1*2 in healthy controls (96.0% and 4.0% for SULT1A1*1 an SULT1A1*2, respectively), the allelic frequencies of SULT1A1 polymorphisms in the cancer patients were not statistically significant. However, it appears to influence the age of onset among early-onset breast cancer patients