Establishment of an Allo-Transplantable Hamster Cholangiocarcinoma Cell Line and Its Application for In Vivo Screening of Anti-Cancer Drugs

Opisthorchis viverrini (O. viverrini) is a well-known causative agent of cholangiocarcinoma (CCA) in humans. CCA is very resistant to chemotherapy and is frequently fatal. To understand the pathogenesis of CCA in humans, a rodent model was developed. However, the development of CCA in rodents is time-consuming and the xenograft-transplantation model of human CCA in immunodeficient mice is costly. Therefore, the establishment of an in vivo screening model for O. viverrini-associated CCA treatment was of interest. We developed a hamster CCA cell line, Ham-1, derived from the CCA tissue of O. viverrini-infected and N-nitrosodimethylamine-treated Syrian golden hamsters. Ham-1 has been maintained in Dulbecco's Modified Essential Medium supplemented with 10% fetal bovine serum for more than 30 subcultures. These cells are mostly diploid (2n=44) with some being polyploid. Tumorigenic properties of Ham-1 were demonstrated by allograft transplantation in hamsters. The transplanted tissues were highly proliferative and exhibited a glandular-like structure retaining a bile duct marker, cytokeratin 19. The usefulness of this for in vivo model was demonstrated by berberine treatment, a traditional medicine that is active against various cancers. Growth inhibitory effects of berberine, mainly by an induction of G1 cell cycle arrest, were observed in vitro and in vivo. In summary, we developed the allo-transplantable hamster CCA cell line, which can be used for chemotherapeutic drug testing in vitro and in vivo.

Cancer Stem Cells

 Knowledge and progress in stem cell technology provide a new insight into cancer biology. The rare population of malignant cells with the stem cell-like features, termed “cancer stem cells”, has been demonstrated to be essential for the development and growth of cancer.  Self-renewal and capability to differentiate into multiple lineages are the parallel properties of cancer stem cells with those of normal stem cells. Given these similar features, it is postulated that cancer stem cells may arise by mutation of general stem cells or progenitor of stem cell with the retaining self-renewal property. The concept of cancer stem cells can explain the behavior and progression of tumor. For example, cancer stem cells can be the source of various malignant cells found in a primary tumor.  They may be the reservoir of drug and radiation resistant cells that cause a treatment failure and recurrence of cancer. They can also give rise to distant metastases if they spread out the primary site.  Therefore, eradication of cancer stem cells may be essential to achieve stable, long-lasting emission, and even a cure, of cancer. The development of early detection based on the concept of cancer stem cells is also an important priority to be established.

Inhibitory Effects of Vitamin D in Cancers

Vitamin D is a lipid soluble vitamin that is metabolically converted to an active metabolite, 1α,25-dihydroxyvitamin D (calcitriol).  This active metabolite plays an essential role in controlling a wide range of biological activities such as calcium-bone homeostasis. In the past two decades, the effects of vitamin D in the regulation of cell proliferation, apoptosis, metastasis and angiogenesis both in vitro and in vivo have been accumulated. Moreover, results from Phase I and phase II trials of calcitriol either alone or in combination with chemotherapeutic agents indicates its tumor suppression effects. However, therapeutic role of calcitriol has been encountered with hypercalcemic side effect in most cases. To solve this problem, vitamin D analogues with less calcemic effect have been developed. These analogues have been tested for its efficacy in a variety of cancer treatment, such as prostate, breast, pancreatic, and liver cancers, etc. Results from several clinical trials indicated that the administration of high-dose calcitriol and its analogues is safe and feasible. Thus, the promises of vitamin D from many studies may lead us to a new strategy in cancer therapy of upcoming future.

Detection of DNA methylation of p16INK4a in hepatocellular carcinoma by methylation specific-polymerase chain reaction

The purpose of this study is to investigate aberrant methylation of p16INK4a in hepatocellular carcinoma (HCC). We determined the methylation status of CpG island of p16INK4a in 29 HCC and corresponding normal liver tissues by methylation specific-PCR method. Aberrant methylation status was detected in 41.4% of tumors and 6.9% of corresponding normal liver tissues. No significant correlations between methylation status and clinico-pathological data were found. In addition, survival analysis by multivariate Cox regression analysis showed that aberrant methylation status of p16INK4a was not an independent prognostic factor for poor survival among HCC patients. Our findings demonstrated that methylation of p16INK4a were detectable in HCC tissues of Thai patients and suggested that hypermethylation of p16INK4a may contribute to the hepatocellular carcinogenesis.