Anucha Puapairoj

Leptospira interrogans requires heme oxygenase for disease pathogenesis

We recently characterised the Leptospira interrogans heme oxygenase (hemO) gene and showed that HemO was required for growth with hemoglobin as the sole iron source. Here we investigated the role of HemO in pathogenesis. Hamsters inoculated with the hemO mutant showed 83% survival, compared with 33% for a control mutant (intergenic transposon insertion). Lung pathology was consistent with survival data, showing that HemO contributes significantly to pathogenesis and heme is a major in vivo iron source for L. interrogans. This is only the second defined, attenuated mutant in pathogenic Leptospira and the first to define function of the mutated gene.

Myristoylated alanine-rich C kinase substrate phosphorylation promotes cholangiocarcinoma cell migration and metastasis via the protein kinase C-dependent pathway

(Cancer Sci 2010; 101: 658–665)

Cepharanthine exerts antitumor activity on cholangiocarcinoma by inhibiting NF-κB

Cholangiocarcinoma (CCA) is a major cause of cancer deaths in northeast Thailand. It is aggressive, highly metastatic, and responds poorly to traditional chemotherapy. We demonstrated the potential for Cepharanthine (CEP), a biscoclaurine alkaloid extracted from Stephania cepharantha, to treat CCA. CEP significantly inhibited growth of human CCA cell lines in a dose‐ and time‐dependent manner, regardless of the histologic type of tumor origin. Increasing cell apoptosis via caspase‐3 and capase‐9 activation was demonstrated in CEP‐treated cells. We found that CEP controlled the growth of CCA cells through nuclear factor‐kappa B (NF‐κB) inactivation by inhibiting nuclear translocation. CEP treatment effectively reduced tumor size in CCA‐inoculated mice without serious side effects. CEP also increased cell apoptosis in primary histocultures of CCA patients’ tissues; this was demonstrated by immunohistochemistry using TUNEL staining. Our results suggest that CEP possesses therapeutic potential against human CCA. (Cancer Sci 2010)

PRKAR1A is overexpressed and represents a possible therapeutic target in human cholangiocarcinoma

The protein kinase A regulatory subunit 1 alpha (PRKAR1A/PKAI) pathway is overexpressed in varieties of tumors and cancer cell lines including cholangiocarcinoma (CCA), although its role in CCA growth modulation is unclear. In our study, we evaluated the effect of PRKAR1A/PKAI targeting on CCA cell proliferation. Real‐time PCR demonstrated an increased mRNA expression of PRKAR1A/PKAI, whereas protein kinase A regulatory subunit 2 beta (PRKAR2B/PKAII) was downregulated in human CCA tissues and CCA cell lines. Immunohistochemistry of human CCA tissues revealed increased PRKAR1A with decreased PRKAR2B protein expression. Moreover, CCA cell lines showed abundantly expressed PRKAR1A, while lacking PRKAR2B expression. Silencing PRKAR1A expression induced growth inhibition and apoptosis of CCA cells, with an associated decrease in mitogen‐activated protein kinases, PI3K/Akt, JAK/STAT and Wnt/β‐catenin pathway signaling. The inhibition of PKA using a PKA inhibitor and cAMP analogs also led to a significant cell growth inhibition. In conclusion, our study reports the overexpression as well as molecular mechanisms by which PRKAR1A/PKA regulates human CCA cell growth. Importantly, abrogation of gene expression caused significant CCA cell growth inhibition, oncogenic signaling and coupled apoptosis induction, suggesting PRKAR1As potential as a drug target for CCA therapy.

Histology of Gastritis and Helicobacter pylori Infection in Thailand: a Nationwide Study of 3776 Cases

Background. Dyspepsia is a very common problem in Thailand. Etiology of gastritis, incidence of Helicobacter pylori and mode of transmission of Helicobacter pylori infection in the country was proposed.

Overexpression of vitamin D receptor indicates a good prognosis for cholangiocarcinoma: implications for therapeutics.

Up‐regulation of vitamin D receptor (VDR) expression has been shown in several tumors and is thought to represent an important endogenous response to tumor progression. The authors aimed to verify the expression of VDR and its clinical significance in histologically proven cholangiocarcinoma (CCA).

Tumor necrosis factor-α modulates epithelial mesenchymal transition mediators ZEB2 and S100A4 to promote cholangiocarcinoma progression

The epithelial‐mesenchymal transition (EMT) process strongly contributes to cancer metastasis. This study was to investigate the alteration of EMT‐related proteins (ZEB1, ZEB2 and S100A4) in cholangiocarcinoma (CCA) tissues. The effect of tumor necrosis factor‐α (TNF‐α) on the expression of those molecules in CCA cells was investigated.

Turmeric reduces inflammatory cells in hamster opisthorchiasis

The curcumin compound from turmeric is effective in the treatment of many inflammatory diseases. The aim of our present study was to evaluate the efficacy of turmeric on reducing the histopathological changes of hamster opisthorchiasis. Hamsters were infected with Opisthorchis viverrini and then administered turmeric. Using light microscopic observation, liver function tests for alanine transaminase (ALT), alkaline phosphatase, and direct bilirubin were investigated. The resulting histopathological changes show that turmeric has anti-inflammatory properties—during both N-nitrosodimethylamine administration and O. viverrini infection—by reducing the aggregation of inflammatory cells surrounding the hepatic bile ducts, which correlates with a decreased serum ALT level. The decrease in direct bilirubin levels in the hamsters treated with turmeric suggests that turmeric may enhance biliary contraction. The present study found that turmeric clearly reduces the inflammatory cells in hamster opisthorchiasis at an early stage. This finding may be connected with a reduction in the risk factors of cholangiocarcinoma development.

Involvement of c-Ski Oncoprotein in Carcinogenesis of Cholangiocacinoma Induced by Opisthorchis viverrini and N-nitrosodimethylamine

Opisthorchiasis is the major public health problem in the endemic areas of Thailand and Laos because Opisthorchis viverrini infection causes serious hepatobiliary diseases including CCA. The molecular mechanism of the CCA carcinogenesis induced by the infection remains obscure. To reveal the potential genes and signaling pathways to involve in the carcinogenesis, the present study investigated the expression of c-Ski, an oncogene, and two TGF-β signaling pathway relative genes, TGF-β and Smad4, during the development of CCA induced by O. viverrini infection in hamster model, and in human opisthorchiasis associated CCA. The results showed that the expression of c-Ski gene was greatly up-regulated during the carcinogenesis of CCA in hamster model. The overexpression of c-Ski was confirmed by immunohistological staining result which showed the increased expression of c-Ski protein in cytoplasm of the epithelial lining of hepatic bile ducts. Moreover, the immunohistological staining of the specimens of human opisthorchiasis associated CCA revealed the up-regulated expression of c-Ski and Smad4 proteins in the cytoplasm of the epithelial lining of hepatic bile ducts and stomal fibrosis respectively. The expression of TGF-β and Smad4 were up-regulated, which expression kinetics was time-dependent of CCA development. These results suggest that c-Ski is likely involved in the carcinogenesis of CCA induced by O. viverrini infection through regulating TGF-β signaling pathway.

Candidate genes involving in tumorigenesis of cholangiocarcinoma induced by Opisthorchis viverrini infection

Opisthorchiasis-associated cholangiocarcinoma (CCA) is one of main public health problems in Opisthorchis viverrini endemic areas. Although the definite relationship between prevalence of CCA and the parasite infection has been demonstrated, the molecular mechanism of tumorigenesis is still unknown. In the present study, by using animal model of opisthorchiasis-associated CCA, a kinetic analysis of cDNA microarray was performed to screen the candidate genes that involve in the development of opisthorchiasis-associated CCA. Microarray analysis revealed that the expressions of 131 genes were up-regulated during the development of CCA, including the genes relative to cell proliferation, differentiation and transformation, cell growth and cycle regulation, apoptosis, DNA repair, and cytoskeletal structure. The expressions of 145 genes were down-regulated, including the genes relative to metabolic enzymes, tumor suppressor, apoptosis, and oxidative response and oxidation reduction. The present study listed up the candidate genes involving tumorigenesis, provided molecular information on the development of opisthorchiasis-associated CCA and the potential biomarkers for diagnosis and therapy, and suggested that the increased expression of cell differentiation, proliferation, transformation-related genes, and decreased expression of metabolic enzymes may play important roles in the tumorigenesis of CCA.