Expanding surgical treatment of pancreatic cancer: the role of regional chemotherapy

Deuterium Depletion Inhibits Cell Proliferation, RNA and Nuclear Membrane Turnover to Enhance Survival in Pancreatic Cancer

The effects of deuterium-depleted water (DDW) containing deuterium (D) at a concentration of 25 parts per million (ppm), 50 ppm, 105 ppm and the control at 150 ppm were monitored in MIA-PaCa-2 pancreatic cancer cells by the real-time cell impedance detection xCELLigence method. The data revealed that lower deuterium concentrations corresponded to lower MiA PaCa-2 growth rate. Nuclear membrane turnover and nucleic acid synthesis rate at different D-concentrations were determined by targeted [1,2-13C2]-D-glucose fate associations. The data showed severely decreased oxidative pentose cycling, RNA ribose 13C labeling from [1,2-13C2]-D-glucose and nuclear membrane lignoceric (C24:0) acid turnover. Here, we treated advanced pancreatic cancer patients with DDW as an extra-mitochondrial deuterium-depleting strategy and evaluated overall patient survival. Eighty-six (36 male and 50 female) pancreatic adenocarcinoma patients were treated with conventional chemotherapy and natural water (control, 30 patients) or 85 ppm DDW (56 patients), which was gradually decreased to preparations with 65 ppm and 45 ppm deuterium content for each 1 to 3 months treatment period. Patient survival curves were calculated by the Kaplan-Meier method and Pearson correlation was taken between medial survival time (MST) and DDW treatment in pancreatic cancer patients. The MST for patients consuming DDW treatment (n = 56) was 19.6 months in comparison with the 6.36 months' MST achieved with chemotherapy alone (n = 30). There was a strong, statistically significant Pearson correlation (r = 0.504, p < 0.001) between survival time and length and frequency of DDW treatment.

The Membrane Protein Sortilin Can Be Targeted to Inhibit Pancreatic Cancer Cell Invasion

Pancreatic cancer has a dismal prognosis, and there is no targeted therapy against this malignancy. The neuronal membrane protein sortilin is emerging as a regulator of cancer cell development, but its expression and impact in pancreatic cancer are unknown. This study found that sortilin expression was higher in pancreatic cell lines versus normal pancreatic ductal epithelial cells, as shown by Western blot analysis and mass spectrometry. The increased sortilin level in pancreatic cancer cells was confirmed by immunohistochemistry in a series of 99 human pancreatic adenocarcinomas versus 48 normal pancreatic tissues (P = 0.0014). Sortilin inhibition by siRNA and the pharmacologic inhibitor AF38469 strongly reduced the adhesion and invasion of pancreatic cancer cells without affecting cell survival and viability. Sortilin inhibition also decreased the phosphorylation of the focal adhesion kinase in Tyr925. Together, these data show that sortilin contributes to pancreatic cancer invasion and could eventually be targeted in therapy.

miR-128 induces pancreas cancer cell apoptosis by targeting MDM4

MicroRNAs (miRNA/miRs) are small, non-coding RNA molecules (19-25 nucleotides in length), which function to regulate gene expression. It has been reported that miR-128 serves an important role in regulating cancer cell growth; increasing evidence has indicated that the expression of miR-128 is decreased in pancreatic cancer (PC) cells. However, the specific mechanisms of miR-128 in regulating PC cell growth are unclear. In the present study, it was confirmed that the expression of miR-128 was significantly decreased within PC tissues compared with adjacent normal tissues via reverse transcription-quantitative polymerase chain reaction analysis. In addition, miR-128 mimics inhibited PC MIA-PaCa2 cell growth by enhancing cell apoptosis in a caspase-dependent manner. Furthermore, the results of the present study demonstrated that double minute 4 (MDM4) may be a direct target for miR-128 via a dual luciferase report assay; miR-128 may inhibit MDM4 expression, and increase p53 and cleaved caspase-3 protein expression levels. In summary, the present study indicated that miR-128 is downregulated in PC, and it may be a promising target for future PC diagnosis and treatment.

The effect of metformin on survival of patients with pancreatic cancer: a meta-analysis

We conducted a meta-analysis to analyse the effect of metformin on survival of pancreatic cancer patients at various stages. We performed a systematic search of PubMed, Embase, Cochrane, and Web of Science to identify all relevant studies. Summary hazard ratios (HR) of survival and 95% confidence intervals (95% CI) were calculated with a fixed or random effects model according to inter-study heterogeneity. Nine retrospective cohort studies and two randomized controlled trials (RCTs) were eligible. There was a significant improvement in survival (HR = 0.86, 95% CI 0.76–0.97; P < 0.05) in the metformin group compared with control. Subgroup analysis indicated that metformin improved survival in patients with resection (HR = 0.79, 95% CI 0.69–0.91; P < 0.05) and patients with locally advanced tumors (HR = 0.68, 95% CI 0.55–0.84; P < 0.05) but not in patients with metastatic tumors, even when RCT data were included (HR = 0.99, 95% CI 0.70–1.40; P > 0.05), or were excluded (HR = 0.89, 95% CI 0.61–1.31; P > 0.05). This meta-analysis indicated that the effect of metformin does correlate with tumor stage but should be prudently considered given the limited and variable studies performed to data.

Preclinical efficacy of the novel competitive NAMPT inhibitor STF-118804 in pancreatic cancer

NAD salvage is one of the pathways used to generate NAD in mammals. Nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in this pathway, uses nicotinamide (NAM) to generate nicotinamide mononucleotide (NMN). NMN is one of the main precursors of NAD synthesis in cells. Our previous study showed the importance of NAMPT in maintaining NAD levels in pancreatic ductal adenocarcinoma cells (PDAC), and that the NAMPT inhibitor FK866 decreased pancreatic cancer growth. We now tested the effect of STF-118804, a new highly specific NAMPT inhibitor, in models of pancreatic ductal adenocarcinoma. STF-118804 reduced viability and growth of different PDAC lines, as well as the formation of colonies in soft agar. In addition, STF-118804 decreased glucose uptake, lactate excretion, and ATP levels, resulting in metabolic collapse. STF-118804 treatment activated AMPK and inhibited of mTOR pathways in these cells. This effect was significantly potentiated by pharmacological AMPK activation and mTOR inhibition. Exogenous NMN blocked both the activation of the AMPK pathway and the decrease in cell viability. Panc-1 cells expressing GFP-luciferase were orthotopically implanted on mice pancreas to test the in vivo effectiveness of STF-118804. Both STF-118804 and FK866 reduced tumor size after 21 days of treatment. Combinations of STF-118804 with chemotherapeutic agents such as paclitaxel, gemcitabine, and etoposide showed an additive effect in decreasing cell viability and growth. In conclusion, our preclinical study shows that the NAMPT inhibitor STF-118804 reduced the growth of PDAC in vitro and in vivo and had an additive effect in combination with main current chemotherapeutic drugs.

Current therapeutic strategies for advanced pancreatic cancer: A review for clinicians

Pancreatic cancer (PC) would become the second leading cause of cancer death in the near future, despite representing only 3% of new cancer diagnosis. Survival improvement will come from a better knowledge of risk factors, earlier diagnosis, better integration of locoregional and systemic therapies, as well as the development of more efficacious drugs rising from a deeper understanding of disease biology. For patients with unresectable, non-metastatic disease, combined strategies encompassing primary chemotherapy and radiation seems to be promising. In fit patients, new polychemotherapy regimens can lead to better outcomes in terms of slight but significant survival improvement associated with a positive impact on quality of life. The upfront use of these regimes can also increase the rate of radical resections in borderline resectable and locally advanced PC. Second line treatments showed to positively affect both overall survival and quality of life in fit patients affected by metastatic disease. At present, oxaliplatin-based regimens are the most extensively studied. Nonetheless, other promising drugs are currently under evaluation. Presently, in addition to surgery and conventional radiation therapy, new locoregional treatment techniques are emerging as alternative options in the multimodal approach to patients or diseases not suitable for radical surgery. As of today, in contrast with other types of cancer, targeted therapies failed to show relevant activity either alone or in combination with chemotherapy and, thus, current clinical practice does not include them. Up to now, despite the fact of extremely promising results in different tumors, also immunotherapy is not in the actual therapeutic armamentarium for PC. In the present paper, we provide a comprehensive review of the current state of the art of clinical practice and research in PC aiming to offer a guide for clinicians on the most relevant topics in the management of this disease.

Metformin Increases Sensitivity of Pancreatic Cancer Cells to Gemcitabine by Reducing CD133+ Cell Populations and Suppressing ERK/P70S6K Signaling

The prognosis of pancreatic cancer remains dismal, with little advance in chemotherapy because of its high frequency of chemoresistance. Metformin is widely used to treat type II diabetes, and was shown recently to inhibit pancreatic cancer stem cell proliferation. In the present study, we investigated the role of metformin in chemoresistance of pancreatic cancer cells to gemcitabine, and its possible cellular and molecular mechanisms. Metformin increases sensitivity of pancreatic cancer cells to gemcitabine. The mechanism involves, at least in part, the inhibition of CD133⁺ cells proliferation and suppression of P70S6K signaling activation via inhibition of ERK phosphorylation. Studies of primary tumor samples revealed a relationship between P70S6K signaling activation and the malignancy of pancreatic cancer. Analysis of clinical data revealed a trend of the benefit of metformin for pancreatic cancer patients with diabetes. The results suggested that metformin has a potential clinical use in overcoming chemoresistance of pancreatic cancer.

BRD4 promotes pancreatic ductal adenocarcinoma cell proliferation and enhances gemcitabine resistance

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive carcinoma with a poor prognosis. To date, there is no effective treatment for this fatal disease. The manipulation of epigenetic proteins, such as BRD4, has recently emerged as an alternative therapeutic strategy. Our objective was to analyze the effect of BRD4 on the cell progression and chemoresistance of PDAC and the novel mechanisms involved. In the present study, we firstly revealed that the expression of BRD4 was significantly upregulated in PDAC cell lines, compared to that in human pancreatic duct epithelial cells. An in vitro assay showed that the suppression of BRD4 impaired PDAC cell viability and proliferation. Similarly, the tumor growth rate was also decreased in vivo after silencing of BRD4. Furthermore, we showed that the expression of BRD4 was increased after treatment with gemcitabine (GEM). Combination treatment of GEM and BRD4 silencing had a synergistic effect on the chemotherapeutic efficacy in the PANC-1 and MIAPaCa-2 cell lines, and significantly promoted apoptosis. In particular, we demonstrated that BRD4 activated the Sonic hedgehog (Shh) signaling pathway members in a ligand-independent manner in the PDAC cells. Together, our results indicate the important role of BRD4 in PDAC cell proliferation and chemoresistance and suggests that BRD4 is a promising target directed against the transcriptional program of PDAC.

Metformin is associated with reduced risk of pancreatic cancer in patients with type 2 diabetes mellitus: a systematic review and meta-analysis

AIMS

Recent epidemiological studies indicated that use of metformin might decrease the risk of various cancers among patients with type 2 diabetes mellitus (T2DM). However, its influence on pancreatic cancer was controversial. Therefore, we did a meta-analysis of currently available observational studies on the issue.

METHODS

We did a PubMed and ISI Web of Science search for observational articles. The pooled relative risk (RR) was estimated using a random-effect model. Heterogeneity was evaluated using I(2) statistic. Subgroup analysis was performed to explore the source of heterogeneity and confirm the overall estimates. Publication bias was also examined.

RESULTS

The analysis included 11 articles (13 studies) comprising 10 cohort studies and 3 case-control studies. Use of metformin was associated with a significant lower risk of pancreatic cancer [RR 0.63, 95% confidence internal (CI) 0.46-0.86, p=0.003]. In a total 11 subgroup analyses, 5 provided the consistent result with pooled effect estimates of overall analysis. No publication bias was detected by Begg's (Z=-0.79, p=0.428) and Egger's test (t=-0.92, p=0.378).

CONCLUSIONS

From present observational studies, use of metformin appears to be associated with a reduced risk of pancreatic cancer in patients with T2DM. Further investigation is needed.

Comprehensive surgical management of pancreatic cancer

Pancreatic cancer is a malignancy with a very poor prognosis. Currently, surgery-based comprehensive management may be the only treatment able to significantly improve long-term survival. Radical resection is the first choice for pancreatic cancer patients. Unfortunately, less than 20% of patients are found to have resectable tumors at the time of diagnosis. In addition, only few people can acquire long-term survival even after radical resection because of recurrence and metastasis after surgery. Therefore, surgery-based comprehensive management, including iodine-125 seed implantation, sustained release 5-fluorouracil, argon-helium cryosurgery, radiofrequency ablation, immunotherapy, and regional intra-arterial infusion chemotherapy, may improve the survival and life quality of pancreatic cancer patients.

Inhibiting signal transducer and activator of transcription-3 increases response to gemcitabine and delays progression of pancreatic cancer

Background

Among the solid tumors, human pancreatic ductal adenocarcinoma (PDAC) has the worst prognosis. Gemcitabine is the standard first line of therapy for pancreatic cancer but has limited efficacy due to inherent or rapid development of resistance and combining EGFR inhibitors with this regimen results in only a modest clinical benefit. The goal of this study was to identify molecular targets that are activated during gemcitabine therapy alone or in combination with an EGFR inhibitor.

Methods

PDAC cell lines were used to determine molecular changes and rates of growth after treatment with gemcitabine or an EGFR inhibitor, AG1478, by Western blot analysis and MTT assays respectively. Flow cytometric analysis was performed to study the cell cycle progression and rate of apoptosis after gemcitabine treatment. ShRNA was used to knockdown STAT3. An in vivo orthotopic animal model was used to evaluate STAT3 as a target. Immunohistochemical analysis was performed to analyze Ki67 and STAT3 expression in tumors.

Results

Treatment with gemcitabine increased the levels of EGFR^Tyr1068 and ERK phosphorylation in the PDAC cell lines tested. The constitutive STAT3^Tyr705 phosphorylation observed in PDAC cell lines was not altered by treatment with gemcitabine. Treatment of cells with gemcitabine or AG1478 resulted in differential rate of growth inhibition. AG1478 efficiently blocked the phosphorylation of EGFR^Tyr1068 and inhibited the phosphorylation of down-stream effectors AKT and ERKs, while STAT3^Tyr705 phosphorylation remained unchanged. Combining these two agents neither induced synergistic growth suppression nor inhibited STAT3^Tyr705 phosphorylation, thus prompting further studies to assess whether targeting STAT3 improves the response to gemcitabine or AG1478. Indeed, knockdown of STAT3 increased sensitivity to gemcitabine by inducing pro-apoptotic signals and by increasing G1 cell cycle arrest. However, knockdown of STAT3 did not enhance the growth inhibitory potential of AG1478. In vivo orthotopic animal model results show that knockdown of STAT3 caused a significant reduction in tumor burden and delayed tumor progression with increased response to gemcitabine associated with a decrease in the Ki-67 positive cells.

Conclusions

This study suggests that STAT3 should be considered an important molecular target for therapy of PDAC for enhancing the response to gemcitabine.

Low concentrations of metformin selectively inhibit CD133⁺ cell proliferation in pancreatic cancer and have anticancer action

Pancreatic cancer is the fourth leading cause of cancer related deaths in the United States. The prognosis remains dismal with little advance in treatment. Metformin is a drug widely used for the treatment of type II diabetes. Recent epidemiologic data revealed that oral administration of metformin is associated with a reduced risk of pancreatic cancer, suggesting its potential as a novel drug for this disease. Many studies have demonstrated the in vitro anticancer action of metformin, but the typically used concentrations were much higher than the in vivo plasma and tissue concentrations achieved with recommended therapeutic doses of metformin, and low concentrations of metformin had little effect on the proliferation of pancreatic cancer cells. We examined the effect of low concentrations of metformin on different subpopulations of pancreatic cancer cells and found that these selectively inhibited the proliferation of CD133⁺ but not CD24⁺CD44⁺ESA⁺ cells. We also examined the effect of low concentrations of metformin on cell invasion and in vivo tumor formation, demonstrating in vitro and in vivo anticancer action. Metformin was associated with a reduction of phospho-Erk and phospho-mTOR independent of Akt and AMPK phosphorylation. CD133⁺ pancreatic cancer cells are considered to be cancer stem cells that contribute to recurrence, metastasis and resistance to adjuvant therapies in pancreatic cancer. Our results provide a basis for combination of metformin with current therapies to improve the prognosis of this disease.