Midkine mRNA is overexpressed in pancreatic cancer.

PURPOSE: Midkine (MK) has been reported to be a possible molecular marker for the diagnosis of pancreatic cancer. We investigated the feasibility of quantitative analysis of MK mRNA by quantitative real-time RT-PCR (qRT-PCR) as a promising tool for the diagnosis of pancreatic cancer. RESULTS: We found that pancreatic cancer tissues expressed significantly higher levels of MK mRNA than intraductal pancreatic mucinous neoplasm (IPMN) and non-neoplastic pancreatic tissues (P < 0.05); in contrast, we did not find any differences in MK mRNA expression between IPMN and non-neoplastic pancreatic tissues. Additionally, we observed that poorly differentiated carcinoma samples expressed higher levels of MK mRNA than well-differentiated carcinoma samples, although a significant difference was not observed. CONCLUSIONS: The present data suggests that quantitative analysis of MK mRNA provides an objective and sensitive evaluation and may be a promising modality for the diagnosis of pancreatic cancer and the prediction of its prognosis.

Down-regulation of deoxycytidine kinase enhances acquired resistance to gemcitabine in pancreatic cancer.

BACKGROUND: The functional roles of deoxycytidine kinase (dCK) in acquired resistance to gemcitabine remain unknown in pancreatic cancer. Here, the functional involvement of dCK in gemcitabine-resistance of pancreatic cancer was investigated. MATERIALS AND METHODS: The levels of the dCK gene as well as other gemcitabine-related genes (hENT1, RRM1 and RRM2) were analyzed in gemcitabine-resistant pancreatic cancer cells (GR cells) using quantitative real-time reverse transcription polymerase chain reaction. The effects of inhibition of these genes on sensitivity to gemcitabine were evaluated. RESULTS: In GR cells, expression of dCK was significantly reduced compared with that of parental cells (p < 0.05). The dCK-targeting siRNA significantly reduced gemcitabine sensitivity (p < 0.01) without affecting cell proliferation. The RRM1- and RRM2-targeting siRNAs increased gemcitabine sensitivity (p < 0.05) and reduced cell proliferation even without gemcitabine treatment. The hENT-targeting siRNA did not affect gemcitabine sensitivity or cell proliferation. CONCLUSION: Down-regulation of dCK specifically enhanced acquired resistance to gemcitabine in pancreatic cancer cells without affecting their proliferation.

Increased expression of ADAM 9 and ADAM 15 mRNA in pancreatic cancer.

BACKGROUND: A disintegrin and metalloproteases (ADAMs) comprise a multifunctional family of membrane-anchored proteins. ADAM 9 and ADAM 15 are involved in cell migration and invasion. Expression of ADAM 9 and ADAM 15 was reported to be altered in several types of cancer. MATERIALS AND METHODS: Quantitative real-time reverse transcription-polymerase chain reaction was performed to measure the expression of ADAM 9 mRNA in bulk pancreatic tissues. Results showed no significant difference in the expression of ADAM 9 mRNA between pancreatic cancer and non-neoplastic pancreas. Primary cultured pancreatic fibroblasts also expressed ADAM 9 mRNA. Therefore, a laser microdissection and pressure catapulting technique was employed to isolate cancer cells from tumor tissues. The expression of ADAM 9 and ADAM 15 mRNA was measured in microdissected samples (cancer cells, n = 11; normal epithelial cells, n = 13 for ADAM 9; cancer cells, n = 9; normal epithelial cells, n = 9 for ADAM 15). RESULTS: Pancreatic cancer cells expressed significantly higher levels of ADAM 9 and ADAM 15 mRNA than did normal pancreatic epithelial cells (p = 0.016 for ADAM 9; p = 0.004 for ADAM 15). CONCLUSION: ADAM 9 and ADAM 15 are involved in pancreatic cancer. Microdissection-based analysis appears to be indispensable for the accurate analysis of the expression of certain ADAM family members in pancreatic cancer.

Twist, a novel oncogene, is upregulated in pancreatic cancer: clinical implication of Twist expression in pancreatic juice.

Despite evidence that Twist, a highly conserved basic helix-loop-helix transcription factor, is a novel oncogene, there are no reports describing Twist expression in pancreatic cancer. Intraductal papillary mucinous neoplasm (IPMN) and pancreatic intraepithelial neoplasia (PanIN) are precursor lesions of pancreatic cancer. To clarify involvement of Twist expression in pancreatic cancer, we used quantitative reverse transcription-polymerase chain reaction and examined Twist expression in pancreatic cancer, IPMN, and non-neoplastic pancreas using bulk tissues (11 cancers, 18 IPMNs, and 15 non-neoplastic pancreata), microdissected cells (cancer from 22 sections, IPMN from 19 sections, PanIN from 6 sections, and pancreatitis-affected epithelial cells from 14 sections), and pancreatic juice (16 from cancer, 28 from IPMN, and 17 from pancreatitis). Twist expression differed significantly between cancer and IPMN bulk tissues (p < 0.0001) but not between cancer and non-neoplastic tissues. Twist expressions differed significantly between microdissected cancer cells, IPMN cells, and pancreatitis-affected cells (all comparisons, p < 0.017). PanIN cells expressed significantly lower levels of Twist than did IDC cells (p = 0.016). Twist expression differed significantly between cancer and IPMN juice samples (p = 0.0002) but not between cancer and pancreatitis juice samples. Receiver operation characteristic curve analyses revealed that measurement of Twist was more useful for discriminating cancer from IPMN than from chronic pancreatitis (p = 0.009). Our results suggest that Twist is involved in tumor progression of pancreatic cancer and that measurement of Twist in pancreatic juice may be useful to differentiate pancreatic cancer from nonmalignant neoplasms such as IPMN.

S100A11, a putative tumor suppressor gene, is overexpressed in pancreatic carcinogenesis.

PURPOSE: Recent microarray analyses revealed that expression of S100A11 is up-regulated in pancreatic cancer. The aim of the present study was to evaluate the association of S100A11 with pancreatic carcinogenesis. EXPERIMENTAL DESIGN: We measured S100A11 mRNA expression in various clinical samples related to pancreatic cancer and its precursor lesions, intraductal papillary mucinous neoplasm (IPMN) and pancreatic intraepithelial neoplasia, by quantitative reverse transcription-PCR. RESULTS: Levels of S100A11 were significantly higher in pancreatic cancer (n=22) and IPMN (n=18) bulk tissues than in nonneoplastic bulk tissues (n=22; P<0.0001 for both). Levels of S100A11 did not differ between pancreatic cancer and IPMN bulk tissues. In microdissection analyses, however, IPMN cells (n=21) expressed significantly higher levels of S100A11 than did cancer cells (n=23; P=0.003). The median level of S100A11 expression was higher in pancreatic intraepithelial neoplasia cells (n=6) than in cancer cells. In pancreatic juice analyses, cancer-related (n=24; P=0.004) and IPMN-related (n=18; P=0.001) juice expressed significantly higher levels of S100A11 than did chronic pancreatitis-related juice (n=23). CONCLUSIONS: The present data suggest that expression of S100A11, a putative tumor suppressor gene, is increased in the early stage of pancreatic carcinogenesis and decreased during subsequent progression to cancer. Analysis of the S100A11 level in pancreatic juice may be an effective tool for screening of patients with high-risk lesions that could progress to pancreatic cancer or detecting early-stage pancreatic cancer.