Autocrine parathyroid hormone-like hormone promotes intrahepatic cholangiocarcinoma cell proliferation via increased ERK/JNK-ATF2-cyclinD1 signaling.

BACKGROUND AND AIMS: Intrahepatic cholangiocarcinoma (ICC) is an aggressive tumor with a high fatality rate. It was recently found that parathyroid hormone-like hormone (PTHLH) was frequently overexpressed in ICC compared with non-tumor tissue. This study aimed to elucidate the underlying mechanisms of PTHLH in ICC development. METHODS: The CCK-8 assay, colony formation assays, flow cytometry and a xenograft model were used to examine the role of PTHLH in ICC cells proliferation. Immunohistochemistry (IHC) and western blot assays were used to detect target proteins. Luciferase reporter, chromatin immunoprecipitation (ChIP) and DNA pull-down assays were used to verify the transcription regulation of activating transcription factor-2 (ATF2). RESULTS: PTHLH was significantly upregulated in ICC compared with adjacent and normal tissues. Upregulation of PTHLH indicated a poor pathological differentiation and intrahepatic metastasis. Functional study demonstrated that PTHLH silencing markedly suppressed ICC cells growth, while specific overexpression of PTHLH has the opposite effect. Mechanistically, secreted PTHLH could promote ICC cell growth by activating extracellular signal-related kinase (ERK) and c-Jun N-terminal kinase (JNK) signaling pathways, and subsequently upregulated ATF2 and cyclinD1 expression. Further study found that the promoter activity of PTHLH were negatively regulated by ATF2, indicating that a negative feedback loop exists. CONCLUSIONS: Our findings demonstrated that the ICC-secreted PTHLH plays a characteristic growth-promoting role through activating the canonical ERK/JNK-ATF2-cyclinD1 signaling pathways in ICC development. We identified a negative feedback loop formed by ATF2 and PTHLH. In this study, we explored the therapeutic implication for ICC patients.

[Claudin-3 expression in colorectal carcinoma and its significance].

OBJECTIVE: To investigate the expression of claudin-3 in colorectal carcinoma and its association with the occurrence, progression and prognosis of colorectal cancer. METHODS: Forty surgical specimens of colorectal carcinoma and 22 adjacent normal tissues resected between October, 2010 and January, 2013 at Nanfang Hospital were examined for claudin-3 expression using immunohistochemistry, which was analyzed in association with the clinicopathological parameters and the survival of the patients. RESULTS: Claudin-3 was expressed mainly on the cell membrane, and its positivity rate was significantly higher in cancer tissues than in normal tissues (92.50% vs 59.09%, P<0.05). In 13 cases claudin-3 expression was detected in both the cancer tissues and adjacent normal tissues with average expression scores of 4.538 and 3.269, respectively (P<0.05). In the cancer tissues, the strongly positive expression rate was significantly higher in poorly differentiated tissues (85.71%) than in well (21.43%) and moderately (36.48%) differentiated tissues (P<0.05), and was higher in cases with lymph node metastasis than in those without (61.11% vs 22.72%, P<0.05). The strongly positive expression rate of claudin-3 was not correlated with the patients'age, gender, tumor location or tumor size (P>0.05). Of the 33 cancer patients followed up, 14 had a postoperative survival time no longer than 3 years and 19 had longer survival time, and their average expression scores differed significantly (4.50 vs 3.526, P<0.05). CONCLUSION: Claudin-3 is over-expressed in colorectal cancer tissues, and its high expression may promote the occurrence and progression of colorectal cancer. Claudin-3 may serve as a molecular biomarker for early diagnosis and prognostic evaluation.