Tsung-Yun Liu

Alteration of the copy number and deletion of mitochondrial DNA in human hepatocellular carcinoma

Somatic mutations in mitochondrial DNA (mtDNA) have been detected in hepatocellular carcinoma (HCC). However, it remains unclear whether mtDNA copy number and mitochondrial biogenesis are altered in HCC. In this study, we found that mtDNA copy number and the content of mitochondrial respiratory proteins were reduced in HCCs as compared with the corresponding non-tumorous livers. MtDNA copy number was significantly reduced in female HCC but not in male HCC. Expression of the peroxisome proliferator-activated receptor γ coactivator-1 was significantly repressed in HCCs (P<0.005), while the expression of the mitochondrial single-strand DNA-binding protein was upregulated, indicating that the regulation of mitochondria biogenesis is disturbed in HCC. Moreover, 22% of HCCs carried a somatic mutation in the mtDNA D-loop region. The non-tumorous liver of the HCC patients with a long-term alcohol-drinking history contained reduced mtDNA copy number (P<0.05) and higher level of the 4977 bp-deleted mtDNA (P<0.05) as compared with non-alcohol patients. Our results suggest that reduced mtDNA copy number, impaired mitochondrial biogenesis and somatic mutations in mtDNA are important events during carcinogenesis of HCC, and the differential alterations in mtDNA of male and female HCC may contribute to the differences in the clinical manifestation between female and male HCC patients.

Comparison of 2-methoxyestradiol-induced, docetaxel-induced, and paclitaxel-induced apoptosis in hepatoma cells and its correlation with reactive oxygen species

Previously, the authors observed that paclitaxel treatment of hepatoma cells resulted in differential cytotoxicity. Whether other antimicrotubule agents (docetaxel and 2‐methoxyestradiol) are more effective than paclitaxel is not clear. Moreover, whether the modulation of reactive oxygen species (ROS) is involved in the drug‐induced growth inhibition of hepatoma cells is not known.

Paclitaxel‐induced apoptosis in human gastric carcinoma cell lines

Gastric cancer is one of the most common cancers in Asia. Chemotherapy and radiation therapy have had limited success. Recently, paclitaxel has been found to be effective against a variety of cancers, including lung, breast, ovary, melanoma, and prostate. Whether paclitaxel is effective in the treatment of gastric cancer is not known and is worthy of investigation.

Association Analysis of Brain-Derived Neurotrophic Factor Val66Met Polymorphisms with Alzheimer’s Disease and Age of Onset

Because of a decrease in central brain-derived neurotrophic factor (BDNF) levels in Alzheimer’s disease (AD) and the important role of BDNF in neuronal survival, BDNF may represent a candidate gene conferring susceptibility to AD. Recently, a functional BDNF Val66Met polymorphism has been associated with AD in an Italian population. In the present study, we investigated a possible role of this BDNF polymorphism in the susceptibility of AD or AD onset in a Chinese population. Comparing AD patients and controls, the distribution of the BDNF genotypes and alleles did not differ significantly. The onset age was not significantly different comparing the three BDNF genotype groups. Our negative findings suggest that it is unlikely that the BDNF Val66Met polymorphism plays a major role in the pathogenesis of AD in the Chinese population and do not support previous findings that homozygosity for the 66Val allele confers an increased risk for AD. Further studies with genetic variations in BDNF relating either to AD-associated depression or to the AD treatment response are suggested.

Accumulation of mitochondrial DNA deletions in human oral tissues — effects of betel quid chewing and oral cancer

Accumulation of mitochondrial DNA (mtDNA) mutations in human tissues has been associated with intrinsic aging and environmental insult. Recently, mtDNA mutations have been detected in various tumors, including head and neck tumors. However, the factors affecting the occurrence and accumulation of mtDNA deletions in tumor tissues are poorly understood. In Taiwan, betel quid chewing is a major risk factor for oral cancer. Using polymerase chain reaction (PCR) techniques, we examined large-scale deletions of mtDNA in 53 pairs of tumor and non-tumor oral tissues from the patients with or without betel quid chewing history. The results revealed that irrespective of the history of betel quid chewing, the incidences of the 4977bp deletion and other deletions of mtDNA were lower in the tumor portion as compared with the non-tumor portion. The average proportions of the 4977bp deleted mtDNA in the tumor tissues of the betel quid chewers and non-betel quid chewers were 13- and 5-fold, respectively, lower than those in the corresponding non-tumor tissues. Moreover, the average proportion of 4977bp deleted mtDNA was significantly higher (P<0.05) in the non-tumor oral tissues of the patients with betel quid chewing history than that of the patients without the history of betel quid chewing. These results suggest that betel quid chewing may increase mtDNA mutation in human oral tissues and that accumulation of mtDNA deletions and subsequent cytoplasmic segregation of these mutations during cell division could be an important contributor to the early phase of oral carcinogenesis.

Determination of aristolochic acids in medicinal plant and herbal product by liquid chromatography–electrospray–ion trap mass spectrometry

This paper describes a liquid chromatography-electrospray-ion trap mass spectrometry (LC-ES-ITMS) method for the determination of aristolochic acid I and II (AA-I and AA-II) in medicinal plants and Chinese herbal remedies. A reversed phase C(18) column with gradient elution was utilized. The effects of mobile phase additives, acetic acid and ammonium acetate, on LC separation and ES ionization were investigated. For both AA-I and AA-II, the [M+NH(4)](+) ion was found to be the precursor ion for target MS/MS analysis. The MS/MS product ion, [M+H-44](+), was used for the quantitative measurement of AA-I and AA-II. The linearity was good from 0.03 to 5 mug ml(-1) and good correlation (r(2)=0.999) over the range examined was determined for both AA. The detection limit based on a signal-to-noise ratio of three was 0.012 and 0.015 mug ml(-1) for AA-I and AA-II, respectively. Various Chinese herbal remedies obtained from renal failure patients and medicinal plants were examined by this newly developed method.

Association analysis of the 5-HT6 receptor polymorphism C267T in Alzheimer's disease

Serotonergic dysfunction has been implicated in the pathogenesis of Alzheimers disease (AD). This association study explores whether the serotonin 6 receptor (5-HT6) polymorphism (C267T) is a susceptibility factor for AD. Statistical analysis showed a significant difference in the genotype and gene frequencies between the AD group and the normal controls (P = 0.006; and P = 0.023, respectively). These findings indicate that the 267C allele of the 5-HT6 gene is a risk factor for AD.

Increased expression of amyloid precursor protein in oral squamous cell carcinoma

In our previous study, we identified amyloid precursor protein (APP) in an oral squamous cell carcinoma (OSCC)‐enriching subtractive hybridization library. Our present study attempts to define the significance of APP expression in the genesis of OSCC. RT‐PCR analysis showed increase in APP mRNA expression for more than 2‐fold in 76% of OSCC (n = 55) relative to corresponding non‐cancerous matched tissues (NCMT). The majority of esophageal SCCs also had increase in APP mRNA expression. OSCC patients exhibiting increase in APP mRNA expression had significantly lower survival rate compared to patients exhibiting the opposite status. Western blotting analysis identified APP751 and APP770 as the major APP isoforms in oral keratinocytes. A high correlation between mRNA and protein expressions of APP was noted in OSCC/NCMT pairs. Immunohistochemistry further showed a remarkable increase of APP in OSCC tissue relative to NCMT. Treatment with an antisense oligonucleotide against APP reduced cellular and secreted APP as well as growth in an OSCC cell line. Our study provides novel clues that APP expression is involved in the proliferation and carcinogenesis of OSCC. Correlated with such pathogenesis was the survival of its victims. The degree of APP expression could serve as an invaluable marker for oral carcinogenesis.

2-methoxyestradiol-induced caspase-3 activation and apoptosis occurs through G2/M arrest dependent and independent pathways in gastric carcinoma cells

2‐Methoxyestradiol (2‐Me), one of the estrogen metabolites, has recently been found to possess anti‐angiogenesis activity in vivo. Many chemotherapeutic agents, such as taxol, docetaxel, and vinblastine, interact with microtubules and then induce apoptosis. It has been suggested that 2‐Me acts on microtubules and results in G2/M‐cycle arrest of tumor cells. Whether 2‐Me induces apoptosis in gastric carcinoma cell lines is not known. Moreover, reactive oxygen species (ROS) produced by 2‐Me may be involved in cytotoxicity of tumor cells. Thus, another objective of this study was to evaluate the relation between cell cycle arrest, ROS formation, and caspase activity levels after 2‐Me treatment in gastric carcinoma cells.

Differential gene expression signature between primary and metastatic head and neck squamous cell carcinoma.

Head and neck squamous cell carcinoma (HNSCC) is a world‐wide malignancy. This study aimed to identify differential gene expression associated with the progression of disease from primary to metastatic HNSCC. Microdissection retrieved pure epithelial cells from paired primary tumours and cervical lymph node metastasis. cDNA microarray analysis and algorithm grouping identified differential mRNA expression of 301 genes. Quantitative reverse transcription‐polymerase chain reaction analysis clarified the up‐regulation of CCL19, CR2, EGR2, FUCA1, RGS1, and SELL, as well as the down‐regulation of IGFBP6 and KLK8 in nodal metastasis compared to primary tumours. Immunohistochemistry confirmed the up‐regulation of SELL and down‐regulation of IGFBP6 in nodal metastasis relative to primary tumours. Interestingly, primary tumours exhibiting higher FUCA1 and SELL expression were associated with significantly worse patient survival. In OECM‐1 HNSCC cells, inhibition of proliferation, migration, and anchorage‐independent growth was noted following knockdown of SELL expression. In SAS HNSCC cells, expression of exogenous SELL resulted in increased invasion, anchorage‐independent growth, and xenographic tumourigenesis in nude mice. Knockdown of FUCA1 and treatment with IGFBP6 inhibited the migration of OECM‐1 cells. Knockdown of RGS1 inhibited the anchorage‐independent growth of SAS cells. Our results provide a useful gene signature profile describing the factors underlying the metastasis of HNSCC to cervical lymph nodes, which may be beneficial for the treatment of HNSCC metastasis. Copyright