Cholangiocarcinoma (CCA) is an aggressive, metastatic bile duct cancer. CCA is difficult to diagnose, and responds poorly to current radio- and chemo-therapy. Piperlongumine (PL) is a naturally-occurring small molecule selectively toxic to cancer cells by targeting reactive oxygen species (ROS). In this study, we demonstrated the potential anticancer activity of PL in CCA. PL markedly induced death in CCA cell lines in a dose- and time-dependent manner through the activation of caspase-3 and PARP. PL also stimulated ROS accumulation in CCA. Co-exposure of PL with the ROS scavenger N-acetyl-L-cysteine or GSH completely blocked PL-induced apoptosis in CCA cell lines. Increased p21 via the p53-independent pathway in PL-treated CCA cells led to G2/M phase arrest and cell apoptosis. In addition, the study showed that PL trigger CCA cell lines death through JNK-ERK activation. Furthermore, the different antioxidant capacity of CCA cell lines also indicates the susceptibility of the cells to PL treatment. Our findings reveal that PL exhibits anti-tumor activity and has potential to be used as a chemotherapeutic agent against CCA.
YKL-40, a chitinase-like glycoprotein, is expressed at a high level in cancer patients. Its exact function is unknown and is the subject of current investigation. Here, we report the correlation of plasma YKL-40 levels with clinicopathological features of cholangiocarcinoma (CCA), a lethal bile duct cancer, particularly prevalent in Northeastern Thailand. Statistical analysis of plasma YKL-40 concentrations in 57 CCA patients and 41 normal healthy subjects gave a median value of 169.5 ng/mL for CCA patients compared with 46.9 ng/mL for the control subjects (P < 0.0001). There was no significant association of plasma YKL-40 levels with patient age, tumor grade, or histology type. However, Kaplan-Meier analysis suggested that the elevated plasma YKL-40 level was particularly associated with short survival in CCA patients (P = 0.038). Immunohistochemical examination of 34 CCA tissues revealed low expression of YKL-40 in CCA cells, but high expression in adjacent intratumoral stroma, liver, and connective tissues. Univariate analysis showed significant association of the intratumoral YKL-40 expression in CCA tissues with the non-papillary type CCA. Addition of rYKL-40 in the culture medium and transient expression of YKL-40 in CCA cell lines were shown to promote the growth and migration of the tumor cells, and that YKL-40 interacted with a cell-surface receptor involved in the Akt/Erk-mediated pathway. In conclusion, our results support the proposal of YKL-40 as a new candidate prognostic biomarker for cancer diseases.
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