DNA methylation markers and serum α-fetoprotein level are prognostic factors in hepatocellular carcinoma.

INTRODUCTION: Hypermethylation of relevant genes may affect the prognosis of patients with cancer. The purpose of this study was to analyze whether methylation of the promoter regions of cell cycle regulators as well as elevated α-Fetoprotein (AFP) levels are useful prognostic factors for patients with hepatocellular carcinoma (HCC). MATERIAL AND METHODS: Nested methylation-specific PCR (nested-MSP) was used to analyze methylation status of the promoter regions of p15, p16, p21, p27, and ras-association domain family 1 (RASSF1A) genes in tumor specimens from 50 patients with HCC. RESULTS: Promoter methylation was most common in the RASSF1A gene (96%), followed by the p16 gene (56%), the p21 gene (44%), the p15 gene (28%), and the p27 gene (2%). Patients with a serum AFP level < 400 ng/mL and an unmethylated p21 promoter had a better prognosis than patients with a serum AFP level ≥ 400 ng/mL and a methylated p21 promoter (overall survival, p = 0.076; disease-free survival, p = 0.016). In addition, patients with full methylation of the promoter region of RASSF1A had a better prognosis than patients with a partially methylated or unmethylated RASSF1A promoter region if their serum AFP level was ≥ 400 ng/mL (overall survival, p = 0.028; disease-free survival, p = 0.078). CONCLUSION: A partially methylated or unmethylated RASSF1A promoter as well as elevated serum AFP level or methylation of p21 in addition to elevated serum AFP level might be associated with poor prognosis in patients with hepatocellular carcinoma.

Androgen receptor CAG repeats, non-random X chromosome inactivation, and loss of heterozygosity at Xq25 in relation to breast cancer risk.

BACKGROUND: The aim of this study was to examine the association of non-random X chromosome inactivation (XCI) and loss of heterozygosity (LOH) at Xq25 with breast cancer development. METHODS: Seventy-nine breast cancer patients, 39 female lung cancer patients, 30 other cancer patients and 77 healthy females were analysed for LOH using a panel of 11 microsatellite markers spanning Xq25. The androgen receptor (AR) gene was chosen as an XCI marker. RESULTS: LOH of at least one microsatellite locus at Xq25 was identified in 46/65 breast cancers examined, while only 10/25 cancers of other origins demonstrated LOH in this region (p = 0.014). The critical deletion region in breast cancer was around marker DXS1047 (47.23%). Moreover, we found that tissues from eight breast cancers showed LOH at all of the informative loci tested at Xq25, while the other 38 showed partial (interstitial or telomeric) alterations at Xq25. Interestingly, the pattern of XCI of these eight breast cancers tended to be non-random. We estimated the frequencies of AR alleles and found that women with two long AR alleles (≥21 CAG repeats) had an increased risk of developing breast cancer, while those with two short AR alleles (<21 CAG repeats) were likely to be normal (p = 0.00069). CONCLUSIONS: The extraordinary high frequencies of LOH at Xq25 found in this study strongly imply that there might be one or more tumour suppressor genes (TSGs) related to the development of breast cancer at Xq25 in the Taiwanese female population.

Role of steric effects in protein-directed enediyne cycloaromatization of neocarzinostatin.

The antibiotic neocarzinostatin comprises a carrier protein with a well-defined cavity for accommodating an active enediyne chromophore. The protein has two disulfides, one (Cys(37)-Cys(47)) lies on the cavity bottom and the other (Cys(88)-Cys(93)) in a constrained short loop. When the chromophore is not bound to the protein, a thiol-induced cycloaromatization of the enediyne into a tetrahydroindacene derivative is responsible for the potent antitumor activity. When it is protein-bound, the protein diverts the cycloaromatization pathway to form a distinct hydroxyisochromene-type product. How the protein directs the enediyne chemistry is an interesting puzzle, and various suggestions have been proposed in the past. We screened more than fifty thiols and manipulated conditions to locate reaction features and search for factors that could influence the protein directing strength. Thiol- and oxygen-concentration-dependence studies suggested that disulfides, which maintain the steric rigidity of the protein, could play a key role in diverting the cycloaromatization pathway. For direct proofs, we made mutations at each of the two disulfides by replacing sulfur atoms with oxygen. Circular dichroism and two-dimensional NMR spectroscopy studies suggested that the mutations changed neither the protein conformation nor the ligand interactions. Analyses of the thiol-induced cycloaromatization revealed that rupture of Cys(37)-Cys(47) made the protein almost completely lose its chemical directing ability, whereas rupture of Cys(88)-Cys(93) had only a minor influence. The results demonstrated that the steric rigidity of the binding cavity, but not necessary the whole protein, played an important role in the protein-directed mechanism.

Consistent sequence variation of Epstein-Barr virus nuclear antigen 1 in primary tumor and peripheral blood cells of patients with nasopharyngeal carcinoma.

PURPOSE: Nasopharyngeal carcinoma (NPC) has been proven as a cancer associated with Epstein-Barr virus (EBV). This study was performed to examine sequence variations of the EBV nuclear antigen 1 gene (EBNA-1) in primary tumor and peripheral-blood cells of NPC patients from Taiwan. EXPERIMENTAL DESIGN: DNA extracted from freshly frozen tumor tissues and corresponding peripheral-blood cells of 13 previously untreated NPC patients were subjected to PCR and direct sequencing using EBNA-1-specific primers. We compared the sequence data and analyzed the clinical outcomes. RESULTS: We obtained a 100% positive-detection rate of EBV DNA in the primary tumors of all patients irrespective of the degree of differentiation. The EBNA-1 gene of all tumor samples was the "V-val" strain, showing the same clustered point mutations. They included 21 nucleotide exchanges, leading to 14 amino-acid mutations and 6 silent exchanges, relative to B95-8 cell line. Two of 13 tumors exhibited an additional point mutation at codon 585. EBV DNA was also detected in peripheral-blood cells of 9 of 13 patients under our experimental conditions. Direct-sequencing data showed match alterations of EBNA-1 gene between the primary tumor and peripheral-blood cells. Tumor relapse was observed in four of nine patients with detectable EBNA-1 DNA in their peripheral-blood cells, whereas none of the four patients without detectable EBNA-1 DNA in their peripheral-blood cells developed tumor relapse. CONCLUSIONS: Results of the current study represents the first demonstration of consistent sequence variation of EBNA-1 in primary tumors and peripheral-blood cells. Clinical observations support that the presence of EBV DNA in the peripheral-blood cells may arise from disseminated cancer cells, resulting in a higher relapse rate and poor prognosis.

Aniline exposure associated with up-regulated transcriptional responses of three glutathione S-transferase Delta genes in Drosophila melanogaster.

Complex transcriptional profile of glutathione S-transferase Delta cluster genes occurred in the developmental process of the fruit fly Drosophila melanogaster. The purpose of this project was to quantify the expression levels of Gst Delta class genes altered by aniline exposure and to understand the relationship between aniline dosages and the variation of Gst Delta genes expressed in D. melanogaster. Using RT-PCR expression assays, the expression patterns of the transcript mRNAs of the glutathione S-transferase Delta genes were revealed and their expression levels were measured at eggs, larvae, pupae and adults. The adult stage was selected for further dose-response assays. After analysis, the results indicated that three Gst Delta genes (Gst D2, Gst D5 and Gst D6) were found to show a peak of up-regulated transcriptional response at 6-8h of exposure of aniline. Furthermore, the dose-response relationship of their induction levels within the dose regiments (from 1.2 to 2.0 µl/tube) had been measured. The expression patterns and annotations of these genes were discussed in the context.

Cloning and functional analysis of pyruvate kinase promoter region from Drosophila melanogaster.

Pyruvate kinase (PK; EC 2.7.1.40) is a key glycolytic enzyme of Drosophila melanogaster. It catalyzes the conversion of phosphoenolpyruvate into pyruvate with the transfer of a phosphate group to ADP to form ATP. The ATP provides energy for cell growth and metabolism, and pyruvate participates in many metabolic reactions. Therefore, PK plays an important role in cell metabolism. Southern blot analysis, PCR, and sequencing were used to determine the content of a Drosophila pyruvate kinase (Pyk) genomic clone, lambdaPK61. The results indicated that the insert of lambdaPK61 comprised 8330 bp upstream of and 7186 bp downstream of the transcription start point of the Pyk gene. The size of the insert was 15,516 bp in total, which contained six genes including Pyk. Deletion mapping was applied to identify the promoter region and cis-acting elements 5' of PyK. Ten serial deletions produced by PCR were inserted upstream of the reporter gene (LacZ) to form recombinant plasmids, which were then transfected into Drosophila S2 cells. The results revealed that the regions -1475 approximately -1033 and -1033 approximately -534 of the 5' end of PyK possessed positive regulatory function for Pyk expression; i.e., increased gene expression. There were redundant putative cis-acting elements, including ecdysone response element (EcRE), E74A, and broad complex zinc finger (BRCZ) binding sites. Both E74A and BRCZ belong to the early genes regulated by ecdysone. This result suggested that Pyk might be regulated by ecdysone, directly or indirectly. However, the results of the developmental profile of Pyk expression by Northern blot analysis suggested that the effects of ecdysone on Pyk were repressive, not inductive. In addition, it was found that in these regions, there were many cis-acting elements related to egg and embryo development. Both -258 approximately -254 and -167 approximately -163 contained a CAAT box, and deletion of these regions decreased reporter gene expression. Therefore, it is suggested that both CAAT boxes are functional and that the promoter of Pyk might be located in the region of -258 approximately +109. No TATA box or downstream promoter element were identified around the transcription start site of Pyk. Additionally, PyK might share a regulatory region with an unknown neighboring gene. It was concluded that Pyk has the characteristics of a housekeeping gene.

Effects of KRAS mutation and polymorphism on the risk and prognosis of oral squamous cell carcinoma.

BACKGROUND: Mutations or single nucleotide polymorphism (SNP) of relevant genes may affect the risk and prognosis of malignancies. The purpose of this study was to analyze whether the KRAS polymorphisms and mutations can be useful prognostic or risk markers in oral squamous cell carcinoma (OSCC). METHODS: DNA was extracted from tumor tissues of 47 patients with OSCC and blood cells of 84 normal controls and subjected to sequencing for the KRAS. RESULTS: No mutation in the KRAS was found in 47 OSCC samples. However, 2 polymorphisms (rs1137282 and rs712) were detected. Individuals with KRAS SNP rs712 genotypes of G/T or T/T have a reduced risk for OSCC than those with genotype G/G (hazard ratio [HR], 0.26; 95% confidence interval [CI], 0.10-0.60; p = .004). The overall survival between different SNPs were not statistically significant (p = .147 for rs1137282 and p = .202 for rs712). CONCLUSION: These data demonstrate a role for rs712 polymorphism of the KRAS in susceptibility of OSCC.

The status of EGFR CA SSR1 is a potential prognostic factor for patients with oral squamous cell carcinoma.

The EGFR is an oncogene known to be involved in the development and progression of many cancers. It has been reported that the expression of EGFR and EGFR CA simple sequence repeat 1 (CA SSR1) repeat numbers in tumors can be useful prognostic factors in several cancer types. The objective of the present study was to analyze whether the EGFR polymorphism can be a useful prognostic factor in OSCC in the Taiwanese population. OSCC tissues were collected from 47 patients by surgical excision. The genotyping of EGFR were performed with the ABI Prism 3100 Genetic Analyzer. OSCC patients had a tendency toward an allelic imbalance of CA SSR1. The results also suggested that OSCC patients who were homozygous for CA SSR1 had a poorer prognosis than those who were heterozygous (P<0.001). Besides, patients with an allelic imbalance of CA SSR1 had significantly lower overall and disease free survival rates than those without, using the Kaplan-Meier method (P<0.001). This suggests that the status of CA SSR1 has the potential to be a useful prognosis factor in OSCC.

Separation of glutathione transferase subunits from Proteus vulgaris by two-dimensional gel electrophoresis.

Cytosolic glutathione transferases of Proteus vulgaris were purified by affinity chromatography and characterized by two-dimensional gel electrophoresis. Four different subunits were identified, and each subunit contained a different molecular mass, ranging from 26.2 kDa to 28.5 kDa; a different pI value, ranging from 8.2 to 9.4; and a different amount of protein fraction, ranging from 10% to 56%. All four subunits existed as basic proteins (pI > 7.0). From these results, we concluded that multiple forms of glutathione transferase enzymes existed in Proteus vulgaris, and four different glutathione transferase subunits were separated by 2-D gel electrophoresis.

Mutational screening of breast cancer susceptibility gene 1 from early onset, bi-lateral, and familial breast cancer patients in Taiwan.

The BRCA1 gene has been shown to be strongly associated with the occurrence of familial breast cancer. The spectrum of BRCA1 gene mutations in breast cancer patients in various populations has been investigated. In this study, patients in Central Taiwan with breast cancer were screened for BRCA1 mutations by sequencing PCR products spanning the coding region and partial intronic regions of the BRCA1 gene. Twelve polymorphisms in four exons and three introns were found. One mutation was found in one patient with familial breast cancer. Two patients showed LOH at the locus of BRCA1. Also found in the Taiwanese population were two common haplotypes and one rare haplotype of BRCA1. These results suggest that the mutation of BRCA1 contributes little to the occurrence of breast cancer in the Taiwanese population.