Neutrophil extracellular traps promote liver micrometastasis in pancreatic ductal adenocarcinoma via the activation of cancer­associated fibroblasts.

Cancer­associated fibroblasts (CAFs) promote the progression of pancreatic ductal adenocarcinoma (PDAC) via tumor­stromal interactions. Neutrophil extracellular traps (NETs) are extracellular DNA meshworks released from neutrophils together with proteolytic enzymes against foreign pathogens. Emerging studies suggest their contribution to liver metastasis in several types of cancer. Herein, in order to investigate the role of NETs in liver metastasis in PDAC, the effects of NET inhibitors on spontaneous PDAC mouse models were evaluated. It was demonstrated that DNase I, a NET inhibitor, suppressed liver metastasis. For further investigation, further attention was paid to liver micrometastasis and an experimental liver metastasis mouse model was used that was generated by intrasplenic tumor injection. Furthermore, DNase I also suppressed liver micrometastasis and notably, CAFs accumulated in metastatic foci were significantly decreased in number. In vitro experiments revealed that pancreatic cancer cells induced NET formation and consequently NETs enhanced the migration of hepatic stellate cells, which was the possible origin of CAFs in liver metastasis. On the whole, these results suggest that NETs promote liver micrometastasis in PDAC via the activation of CAFs.

Usefulness of Oral Xa Inhibitor for Management of Ischemic Stroke Associated with Thrombosis in the Pulmonary Vein Stump after Lung Resection.

OBJECTIVES: Brain infarction is a critical complication after lung resection using video-assisted thoracoscopic surgery. Recent reports have described its association with thrombosis in the pulmonary vein (PV) stump. However, the optimal management of this complication remains controversial. We describe serial 3 cases of brain infarctions associated with thrombosis in the PV stumps, which were successfully treated with the oral Xa inhibitor rivaroxaban. METHODS AND RESULTS: We retrospectively reviewed medical records of 3 patients. The first case was a 72-year-old man who underwent left upper lobectomy for treatment of lung adenocarcinoma. The second case was a 55-year-old man who underwent right lower segmentectomy for treatment of metastatic tumor from Barrett's esophageal carcinoma. The third case was a 73-year-old man who underwent left upper lobectomy for treatment of metastatic tumor from colon adenocarcinoma. In the first case, a large cerebellar infarction was developed and a decompressive craniotomy was performed on postoperative day 4. In the second and the third case, cerebral infarctions in the territories of right middle cerebral arteries occurred on postoperative day 2. In all cases, contrast-enhanced computed tomography demonstrated the thrombi in the stumps of the PVs. They were treated with oral administration of rivaroxaban without adverse effect, and the thrombi in the PVs disappeared within 1 month. DISCUSSION: Blood flow stasis in the long PV stump after lung resection might contribute to thrombosis development. Oral Xa inhibitor rivaroxaban appeared to be safe and useful for the management of ischemic stroke associated with PV thrombosis after lung resection.

Degree of desmoplasia in metastatic lymph node lesions is associated with lesion size and poor prognosis in pancreatic cancer patients.

Pancreatic cancer is characterized by increased hyperplasia of fibrotic tissue, termed desmoplasia, and lymph node metastasis is an independent prognostic factor in this disease. However, there are no reports focused on desmoplasia in pancreatic cancer lymph node metastases. The present study evaluated a range of factors and investigated their association with poor prognosis in pancreatic cancer cases with lymph node metastasis, including the degree of desmoplasia in lesions. To identify the poor prognostic factors associated with lymph node metastasis, the present study retrospectively reviewed the clinical data of 65 patients with lymph node metastases that underwent surgical pancreatic cancer resection between 2007 and 2012 at a single institution. The investigation focused on the degree of fibrosis in metastatic lesions in 216 lymph nodes, and investigated associations with prognosis or clinicopathological findings. The ratios of the fibrotic area in metastatic lymph node lesions were evaluated and classified into three categories, high (≥70%), moderate (10-70%) and low (<10%). Desmoplasia was not observed in cancer-free lymph nodes. The size of metastatic lymph node lesions was additionally measured, and a significant association between metastatic lesion size and the degree of desmoplasia was observed (P<0.001). The degree of desmoplasia was additionally associated with local extranodal invasion. In the analysis of 65 pancreatic cancer patients with metastatic lymph nodes, the presence of multiple metastatic lymph nodes with moderate or high desmoplasia was significantly associated with poor survival (high, P=0.0048; moderate/high, P=0.0075). Of several clinicopathological factors, the presence of multiple metastatic lymph nodes with high or moderate desmoplasia was associated with overall survival in univariate (P=0.0098) and multivariate (P=0.0466) analyses. The degree of desmoplasia in metastatic lymph nodes is associated with lesion size, and the presence of multiple metastatic lymph nodes with desmoplasia is an independent poor prognostic factor, suggesting that the desmoplasia may have an important role in the malignant progression of lymph node metastases.

A 10-year experience of totally extraperitoneal endoscopic repair for adult inguinal hernia.

PURPOSE: Laparoscopic surgery is fast becoming the treatment of choice for inguinal hernia. By reviewing our 10-year experience of performing totally extraperitoneal repair (TEP), we sought to establish its clinical significance in the treatment of adult inguinal hernia. METHODS: We reviewed retrospectively the clinical records of patients who underwent TEP for adult inguinal hernia between January 2003 and December 2012. RESULTS: None of the 303 patients with adult primary or recurrent inguinal hernia in our study needed TEP converted to other procedures or suffered serious complications during the procedure. A significant difference was noted in the operation time between direct (n = 32) vs indirect (n = 128) hernias in the primary unilateral inguinal hernia group (91 ± 27 vs 80 ± 32 min, p = 0.033) and between direct/direct (n = 31) vs indirect/indirect (n = 24) hernias (136 ± 58 vs 89 ± 24 min, p = 0.01) in the primary bilateral inguinal hernia group. The only postoperative complications recorded were four cases of hernia recurrence (1.3 %) and one case of chronic pain (0.3 %). CONCLUSIONS: The results obtained for TEP over 10 years support this as a promising procedure for the treatment of adult inguinal hernia.

[A case of gastrointestinal stromal tumor of the jejunum successfully treated by preoperative induction chemotherapy with imatinib mesylate administered through jejunostomy and subsequent surgical resection].

A 70 -year-old female patient with a palpable mass in the left upper abdomen suffered from abdominal pain and fever. Abdominal computed tomography showed a jejunal tumor 11 cm in diameter with ascites, suggesting rupture of the tumor. Histological diagnosis via endoscopic ultrasound-guided fine needle aspiration indicated c-kit-positive gastrointestinal stromal tumor. Diagnostic laparoscopy demonstrated a large jejunal tumor possibly invading the stomach and pancreas. The patient then underwent tube jejunostomy. Thereafter, preoperative induction chemotherapy with imatinib mesylate(400mg/ body/day)via jejunostomy was administered for 6 months, resulting in 20%reduction of the tumor diameter and disappearance of any indication of stomach and pancreas invasion. The patient then underwent radical partial resection of the jejunum without combined resection of either the stomach or pancreas. Postoperative adjuvant chemotherapy with imatinib mesylate (400mg/body/day)was also indicated. No sign of recurrence has been detected to date after 1 year of follow-up.

Feasibility and safety of intracorporeal esophagojejunostomy after laparoscopic total gastrectomy: inverted T-shaped anastomosis using linear staplers.

BACKGROUND: Although laparoscopic distal gastrectomy has been widely accepted in clinical practice, laparoscopic total gastrectomy (LTG) is not yet familiar because of the difficulty in esophagojejunostomy. The purpose of this study was to evaluate perioperative and short-term outcomes of our procedure of intracorporeal gastrojejunostomy using linear staplers after LTG. METHODS: Of 98 consecutive patients who underwent LTG for gastric cancer in our department between August 2002 and December 2010, 94 patients underwent esophagojejunostomy with a linear stapling device. After October 2007, we modified the esophagojejunostomy; ie, the most recent 57 patients underwent transection of the esophagus in the ventrodorsal direction and insertion of a linear stapler from the anterior wall of the Roux limb to the posterior wall so as to make an inverted T-shaped anastomosis. We evaluated the results in these 57 patients (recent group) and compared them with the results in the earlier 37 patients (early group). RESULTS: The mean operative time in the recent group was 368 to 94.6 min, and the mean estimated blood loss was 57 to 33 g; both were comparable with those in the early group. Neither open conversion nor intraoperative complications were encountered. Two patients experienced anastomotic leakage in the earlier group, but anastomotic leakage did not occur in the recent group. No mortality was encountered. CONCLUSION: We herein report our procedure of intracorporeal gastrojejunostomy using linear staplers after LTG. Our procedure of esophagojejunostomy using linear staplers is safe and feasible and has acceptable morbidity.

Feasibility of laparoscopic gastrectomy for advanced gastric cancer with positive peritoneal cytology.

PURPOSE: The role of gastrectomy for patients with positive peritoneal cytology, but a negative macroscopic peritoneal implant (P-/cy+), remains unclear. The aim of this study was to evaluate laparoscopic gastrectomy for P-/cy+ patients. METHODS: This study reviewed a prospectively maintained gastric cancer database of gastric-cancer patients those underwent surgical resection. P-/cy+ gastric cancer that had invaded the subserosa, or deeper layers, of the stomach wall without distant organ metastases was considered operable in this institution. P-/cy+ patients underwent either open or laparoscopic gastrectomy with D2 lymphadenectomy. The short-term results were examined to assess differences in outcome between the two groups. RESULTS: Eighteen P-/cy+ patients without distant organ metastases underwent surgery between 2000 and 2010. Laparoscopic gastrectomy was performed in nine patients and open gastrectomy in nine patients. The estimated blood loss was significantly smaller, the resumption of food intake earlier, and the length of postoperative hospital stay shorter in the patients that underwent laparoscopic gastrectomy than in the patients that underwent open gastrectomy. There were no significant differences in the 2-year survival rates between the groups. CONCLUSION: Laparoscopic gastrectomy for P-/cy+ patients is a minimally invasive and safe oncologic procedure with good short-term results.

The risk of lymph node metastasis in mucosal gastric carcinoma: especially for a mixture of differentiated and undifferentiated adenocarcinoma.

BACKGROUND/AIMS: Endoscopic submucosal dissection (ESD) is gaining wider acceptance for the treatment of early gastric carcinoma (EGC) and its indication has been extended to mucosal gastric carcinoma with undifferentiated component in some institutes. Our aims were to confirm the frequency of lymph node metastasis in such cases and clarify the demarcation in indications for ESD. METHODOLOGY: We evaluated medical data of 287 patients with mucosal gastric carcinoma who underwent surgical resection between 1996 and 2008. The tumours were histologically classified into purely differentiated (PD), differentiated-predominant mixed (DPM), undifferentiated-predominant mixed (UPM) and purely undifferentiated (PU) types. RESULTS: Lymph node metastasis was identified in seven (2.4%) of the 287 patients and was detected more frequently in UPM (10%, two of 20) and PU (4%, four of 98), compared with PD (none of 148) (p=0.01 and 0.02, respectively). In mixed-type carcinoma, size was a significant risk factor for lymph node metastasis (p=0.04). CONCLUSIONS: It might be better to select gastrectomy rather than ESD for the treatment of mucosal gastric carcinoma with an undifferentiated component.

Japan Pancreatic Cancer Registry; 30th year anniversary: Japan Pancreas Society.

OBJECTIVES: Since 1981, the Japan Pancreas Society has been hosting a nationwide pancreatic cancer registry. To commemorate its 30th anniversary, we review its history and latest achievement. METHODS: During 3 decades, more than 350 leading institutions in Japan contributed voluntarily to register and periodic follow-up. The registry was modified to protect privacy by encrypting and hash algorithm. RESULTS: From 1981 to 2007, 32,619 cumulative records were analyzed. The overall survival of invasive cancer was improved significantly. More patients with earlier stage or with intraductal and cystic neoplasms underwent resection. The strongest prognostic factor of Union for International Cancer Control (UICC) stage IIA and IIB tubular adenocarcinoma in the pancreatic head was histological grade, followed by tumor size, extent of lymph node dissection, and postoperative chemotherapy. The 5-year survival rate of Union for International Cancer Control stage 0 reached 85%. The improvement of survival of patients with invasive cancer in Japan can be attributed to the introduction of effective chemotherapies, regionalization, and the earlier diagnosis and treatment. Simple definition of "early pancreatic cancer" is needed. CONCLUSIONS: At the 30th year anniversary, the Japan Pancreas Society nationwide pancreatic cancer registry is more shining than ever for current perspectives and for future diagnostic and treatment tactics.

MicroRNA-10a is overexpressed in human pancreatic cancer and involved in its invasiveness partially via suppression of the HOXA1 gene.

BACKGROUND: There is increasing evidence that microRNAs are differentially expressed in many types of cancers. Despite progress in analyses of microRNAs in several types of cancers, the functional contributions of microRNAs to pancreatic cancer remain unclear. METHODS: In the present study, the expression levels of specific microRNAs identified by microarray analyses were examined in a panel of 15 pancreatic cancer cell lines. We then investigated the functional roles of these microRNAs in the proliferation and invasion of pancreatic cancer cells. RESULTS: Based on the microarray data, we found frequent and marked overexpression of miR-10a, miR-92, and miR-17-5p in pancreatic cancer cell lines. Microdissection analyses revealed that miR-10a was overexpressed in pancreatic cancer cells isolated from a subset of primary tumors (12 of 20, 60%) compared with precursor lesions and normal ducts (P<.01). In vitro experiments revealed that miR-10a inhibitors decreased the invasiveness of pancreatic cancer cells (P<.01), but had no effect on their proliferation. Inhibition of HOXA1, a target of miR-10a, promoted the invasiveness of pancreatic cancer cells (P<.01). CONCLUSIONS: The present data suggest that miR-10a is overexpressed in a subset of pancreatic cancers and is involved in the invasive potential of pancreatic cancer cells partially via suppression of HOXA1.

Significance of combination therapy of zoledronic acid and gemcitabine on pancreatic cancer.

In the present study, we examined the cytotoxic effects of combination therapy with zoledronic acid (ZOL) and gemcitabine (GEM) on pancreatic cancer cells in vitro and in vivo. Four human pancreatic cancer cell lines were treated with ZOL, GEM or a combination of both, and the effects of the respective drug regimens on cell proliferation, invasion and matrix metalloproteinase (MMP) expression were examined. A pancreatic cancer cell line was also intrasplenically or orthotopically implanted into athymic mice and the effects of these drugs on tumor metastasis and growth in vivo were evaluated by histological and immunohistochemical analyses. Combination treatment with low doses of ZOL and GEM efficiently inhibited the proliferation (P < 0.001) and invasion (P < 0.001) of pancreatic cancer cells in vitro. Western blotting assay revealed that MMP-2 and MMP-9 expression levels were decreased after ZOL treatment. In vivo, combined treatment significantly inhibited tumor growth (P < 0.05) and the development of liver metastasis (P < 0.05). These data revealed that ZOL and GEM, when used in combination, have significant antitumor, anti-metastatic and anti-angiogenic effects on pancreatic cancer cells. The present study is the first to report the significance of the combination treatment of ZOL and GEM in pancreatic cancer using an in vivo model. These data are promising for the future application of this drug regimen in patients with pancreatic cancer.

Single-incision laparoscopy-assisted surgery for bowel obstruction: report of three cases.

We applied single-incision laparoscopy-assisted surgery for several different types of bowel obstruction in selected patients. Before the operation, a long nasal tube was inserted for intestinal decompression and assessment of a stenotic lesion. A specially-designed instrument for single-incision laparoscopic surgery, the SILS Port, was introduced at the umbilicus or proposed ileostomy site. After intracorporeal procedures, extracorporeal resection and reconstruction of the intestine was performed as needed. Three patients with bowel obstruction due to jejunal carcinoma, colonic stenosis, and adhesion underwent single-incision laparoscopy-assisted surgery. The port site was used for subsequent extracorporeal resection and anastomosis of the jejunum in two patients, and for ileostomy in the remaining patient. All of the procedures were completed safely, and there were no postoperative complications. Single-incision laparoscopy can therefore be applied for selected patients with bowel obstruction. In such cases, the preoperative insertion of a long nasal tube for decompression of intestinal contents and assessment of the stenotic lesion is necessary.

Inhibition of p600 expression suppresses both invasiveness and anoikis resistance of gastric cancer.

BACKGROUND: Advanced gastric cancers often metastasize to distant organs and the peritoneum, leading to a poor prognosis. Both invasiveness and resistance to anchorage-independent cell death (anoikis) are important factors in the process of metastasis. p600 (600-kDa protein), recently identified from a cervical cancer cell line, plays a role in both anoikis resistance and cell migration. In this study, we examined whether p600 is involved in the progression of gastric cancer. METHODS: We used both normal gastric mucosal cells and cancer cells laser-microdissected from 42 gastric cancers and their normal counterparts, and compared their p600 mRNA expression levels with quantitative reverse transcriptase-polymerase chain reaction. We inhibited p600 expression in two gastric cancer cell lines with siRNA and examined its effect on the invasiveness and anoikis resistance both in vitro and in vivo. RESULTS: Expression of p600 mRNA was significantly higher in gastric cancer cells than in normal mucosal cells (P = 0.027). The invasion assay revealed that invasiveness was significantly reduced by inhibition of p600 (P < 0.01). In vitro experiments revealed that cell viability and colony-formation capacity under anchorage-independent conditions were significantly reduced by inhibition of p600 (P < 0.05). In vivo experiments also showed that the establishment of intraperitoneal disseminated tumors was significantly suppressed by transient inhibition of p600 (P < 0.001). CONCLUSIONS: Our results strongly suggest that p600 is involved in gastric cancer progression, and has a potential to be a new molecular target for gastric cancer therapy.

hTERT-promoter-dependent oncolytic adenovirus enhances the transduction and therapeutic efficacy of replication-defective adenovirus vectors in pancreatic cancer cells.

Adenovirus-mediated gene therapy shows promise for cancer therapy, but transgene expression of replication-defective adenovirus may be low and transient in clinical settings. Recent reports have shown that the use of a conditionally replication-competent adenovirus (CRAd) enhanced the gene transduction of a replication-defective adenovirus vector. The control of tumor-stromal interactions has also been determined to be important in cancer therapy. In this study, we investigated the effect of the human telomerase reverse transcriptase (hTERT)-CRAd, Ad5/3hTERTE1, which possesses the tumor-specific hTERT promoter with the chimeric fiber 5/3, on the transgene expression and therapeutic efficacy of a replication-defective adenovirus vector expressing NK4 under the control of the CMV promoter, Ad-NK4. In addition, we established a new strategy to target both cancer cells and cancer-stromal interactions. Human pancreatic cancer cells were infected with Ad-NK4 and either Ad5/3hTERTE1 (CRAd-combination group) or Ad5/3hTERTLuc (control-combination group). In the CRAd-combination group, Ad-NK4-delivered transgene expression was increased, leading to an enhanced inhibitory effect on the invasion of cancer cells. In in vivo experiments, NK4 expression within tumors and its inhibitory effect on tumor growth, angiogenesis, and metastasis were enhanced in the CRAd-combination group. These results suggest that hTERT-CRAd enhances the transgene expression and therapeutic efficacies of Ad-NK4, possibly through the in-trans replication of Ad-NK4 induced by adenovirus E1 derived from co-infected hTERT-CRAd. This approach may be a promising combination therapy against advanced pancreatic cancer.

Up-regulation of integrin beta3 in radioresistant pancreatic cancer impairs adenovirus-mediated gene therapy.

Adenovirus-mediated gene therapy is a promising approach for the treatment of pancreatic cancer. We previously reported that radiation enhanced adenovirus-mediated gene expression in pancreatic cancer, suggesting that adenoviral gene therapy might be more effective in radioresistant pancreatic cancer cells. In the present study, we compared the transduction efficiency of adenovirus-delivered genes in radiosensitive and radioresistant cells, and investigated the underlying mechanisms. We used an adenovirus expressing the hepatocyte growth factor antagonist, NK4 (Ad-NK4), as a representative gene therapy. We established two radioresistant human pancreatic cancer cell lines using fractionated irradiation. Radiosensitive and radioresistant pancreatic cancer cells were infected with Ad-NK4, and NK4 levels in the cells were measured. In order to investigate the mechanisms responsible for the differences in the transduction efficiency between these cells, we measured expression of the genes mediating adenovirus infection and endocytosis. The results revealed that NK4 levels in radioresistant cells were significantly lower (P < 0.01) than those in radiosensitive cells, although there were no significant differences in adenovirus uptake between radiosensitive cells and radioresistant cells. Integrin beta3 was up-regulated and the Coxsackie virus and adenovirus receptor was down-regulated in radioresistant cells, and inhibition of integrin beta3 promoted adenovirus gene transfer. These results suggest that inhibition of integrin beta3 in radioresistant pancreatic cancer cells could enhance adenovirus-mediated gene therapy.

MicroRNA-21 modulates biological functions of pancreatic cancer cells including their proliferation, invasion, and chemoresistance.

Due to the poor prognosis of pancreatic cancer, novel diagnostic modalities for early diagnosis and new therapeutic strategy are urgently needed. Recently, microRNA-21 (miR-21) was reported to be strongly overexpressed in pancreatic cancer as well as in other solid cancers. We investigated the functional roles of miR-21, which have not been fully elucidated in pancreatic cancer. miR-21 expression was assessed in pancreatic cancer cell lines (14 cancer cell lines, primary cultures of normal pancreatic epithelial cells and fibroblasts, and a human normal pancreatic ductal epithelial cell line) and pancreatic tissue samples (25 cancer tissues and 25 normal tissues) by quantitative real-time reverse transcription-PCR amplification. Moreover, we investigated the proliferation, invasion, and chemoresistance of pancreatic cancer cells transfected with miR-21 precursor or inhibitor. miR-21 was markedly overexpressed in pancreatic cancer cells compared with nonmalignant cells, and miR-21 in cancer tissues was much higher than in nonmalignant tissues. The cancer cells transfected with the miR-21 precursor showed significantly increased proliferation, Matrigel invasion, and chemoresistance for gemcitabine compared with the control cells. In contrast, inhibition of miR-21 decreased proliferation, Matrigel invasion, and chemoresistance for gemcitabine. Moreover, miR-21 positively correlated with the mRNA expression of invasion-related genes, matrix metalloproteinase-2 and -9, and vascular endothelial growth factor. These data suggest that miR-21 expression is increased in pancreatic cancer cells and that miR-21 contributes to the cell proliferation, invasion, and chemoresistance of pancreatic cancer.

Chemotherapeutic agents potentiate adenoviral gene therapy for pancreatic cancer.

Adenovirus-mediated gene therapy combined with chemotherapeutic agents is expected to represent a new approach for treating pancreatic cancer. However, there have been no reports of definitive effects of chemotherapeutic agents on adenovirus-mediated gene therapies. In the present study, we investigated the effects of chemotherapeutic agents on the transduction efficiency of an adenovirus-based gene therapy. Adenovirus (Ad-NK4) expressing NK4, which acts as a hepatocyte growth factor antagonist, was used as a representative gene therapy. Pancreatic cancer cells infected with Ad-NK4 were treated with chemotherapeutic agents (5-fluorouracil [5FU], cisplatin or etoposide), and the NK4 levels in their culture media were measured. To examine the effects of chemotherapeutic agents in vivo, Ad-NK4 was administered to subcutaneous tumors in mice after treatment with the agents, and the tumor NK4 levels were measured. The NK4 levels in culture media from cells treated with 5FU, cisplatin and etoposide were 5.2-fold (P = 0.026), 6-fold (P < 0.001) and 4.3-fold (P < 0.001) higher than those of untreated cells, respectively. The chemotherapeutic agents also increased Ad-NK4 uptake. The NK4 levels in tumors treated with 5FU, cisplatin and etoposide were 5.4-fold (P = 0.006), 11.8-fold (P < 0.001) and 4.9-fold (P = 0.017) higher than those in untreated tumors, respectively. The present findings suggest that chemotherapeutic agents significantly improve the efficiency of adenovirus-mediated gene transfer in pancreatic cancer. Furthermore, they will contribute to decreases in the adenovirus doses required for gene transfer, thereby controlling the side-effects of adenovirus infection in normal tissues.

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.

Radiation enhances adenoviral gene therapy in pancreatic cancer via activation of cytomegalovirus promoter and increased adenovirus uptake.

PURPOSE: Adenovirus-mediated gene therapy combined with radiation is expected to be a new approach to treat pancreatic cancer. However, there are no reports of definitive effects of radiation on adenovirus-mediated gene therapies. In the present study, we investigated the effect of radiation on the transduction efficiency of an adenovirus-based gene therapy. EXPERIMENTAL DESIGN: We used adenovirus expressing NK4 (Ad-NK4), an antagonist for hepatocyte growth factor, as a representative gene therapy. Pancreatic cancer cells preinfected with Ad-NK4 were irradiated, and NK4 levels in culture media of these cells were measured. We investigated cytomegalovirus (CMV) promoter activity and uptake of adenovirus in these cells. To examine the effect of radiation in vivo, Ad-NK4 was given to irradiated subcutaneous tumors in nude mice, and NK4 levels in tumors were measured. RESULTS: NK4 levels in culture media of irradiated cells were 4.5-fold (P < 0.01) higher than those of nonirradiated cells. Radiation enhanced activation of the CMV promoter and adenovirus uptake (P < 0.01), leading to increased levels of NK4. We found that activation of p38 mitogen-activated protein kinase and up-regulation of dynamin 2 may be involved in the radiation-induced activation of the CMV promoter and adenovirus uptake, respectively. NK4 levels in irradiated tumors were 5.8-fold (P = 0.017) higher than those in nonirradiated tumors. CONCLUSIONS: The present findings suggest that radiation significantly improves the efficiency of adenovirus-mediated gene transfer in pancreatic cancer and probably contributes to decreasing the dose of adenovirus required for gene transfer and controlling side effects of adenovirus infection in nonirradiated normal tissue.