Chemotherapy for pancreatic cancer: from metastatic disease to adjuvant therapy

Development and validation of a UPLC-MS/MS assay for the determination of gemcitabine and its L-carnitine ester derivative in rat plasma and its application in oral pharmacokinetics

A simple and rapid UPLC–MS/MS method to simultaneously determine gemcitabine and its L-carnitine ester derivative (2'-deoxy-2', 2'-difluoro-N-((4-amino-4-oxobutanoyl) oxy)-4-(trimethyl amm-onio) butanoate-cytidine, JDR) in rat plasma was developed and validated. The conventional plasma sample preparation method of nucleoside analogues is solid-phase extraction (SPE) which is time-consuming and cost-expensive. In this study, gradient elution with small particles size solid phase was applied to effectively separate gemcitabine and JDR, and protein precipitation pretreatment was adopted to remove plasma protein and extract the analytes with high recovery(>81%). Method validation was performed as per the FDA guidelines, and the standard curves were found to be linear in the range of 5–4000 ng/ml for JDR and 4–4000 ng/ml for gemcitabine, respectively. The lower limit of quantitation (LLOQ) of gemcitabine and JDR was 4 and 5 ng/ml, respectively. The intra-day and inter-day precision and accuracy results were within the acceptable limits. Finally, the developed method was successfully applied to investigate the pharmacokinetic studies of JDR and gemcitabine after oral administration to rats.

Efficacy of cytokine-induced killer cells in the treatment of elderly patients with metastatic pancreatic adenocarcinoma

Currently, metastatic pancreatic cancer is associated with disappointing survival outcomes. This is largely due to a rapid progression of the disease and a precipitous deterioration in the health of affected individuals, especially elderly patients who are often unable to tolerate chemotherapy. The aim of this study was to evaluate the efficacy and safety of adoptive immunotherapy using cytokine-induced killer cells (CIK) as a first-line treatment for metastatic pancreatic cancer. Between December 2010 and June 2012 eight patients were enrolled in this study. All participants were elderly, suffering from metastatic pancreatic cancer, and unable to tolerate chemotherapy. All patients in this study received R-CIK therapy only as a first-line treatment. In the eight patients, 1 had complete response (CR), 5 had stable disease (SD) and 2 had progression disease (PD). Therefore, the overall response rate (ORR) was 12.5% (1/8) and the disease control rate (DCR) was 75.0% (6/8 patients). The 1-year survival rate was 37.5%, and the median overall survival time (mOS) was 13.04 months (95% CI: 5.9-20.2). The results indicated that no significant positive or negative predictive factors were identified by univariate analysis. The main adverse effect of R-CIK was fever and the side effect rate was 25.0% (2/8). Adoptive immunotherapy using R-CIK cells showed comparable OS to survival data seen in previous trials assessing conventional chemotherapies in elderly patients and the adverse effect is less pronounced.

Combination treatment with comprehensive cryoablation and immunotherapy in metastatic pancreatic cancer

OBJECTIVE

The aim of this study was to retrospectively assess the effect of comprehensive cryosurgery (ablation of intrapancreatic and extrapancreatic tumors) plus immunotherapy in metastatic pancreatic cancer.

METHODS

We divided 106 patients (57 men, 49 women; median age, 65 years) into the cryoimmunotherapy (31 patients), cryotherapy (36 patients), immunotherapy (17 patients), and chemotherapy groups (22 patients). Pretreatment immune function was tested in patients who underwent immunotherapy. Overall survival (OS) after diagnosis of metastatic pancreatic cancer was assessed after a 4-year follow-up.

RESULTS

Median OS was higher in the cryoimmunotherapy (13 months) and cryotherapy groups (7 months) than in the chemotherapy group (3.5 months; both P < 0.001) and was higher in the cryoimmunotherapy group than in the cryotherapy (P < 0.05) and immunotherapy groups (5 months; P < 0.001). In both the cryoimmunotherapy and cryotherapy groups, median OS was higher after multiple cryoablations than after a single cryoablation (P = 0.0048 and 0.041, respectively). In both groups, the median OS was higher in patients with normal immunologic function than in those with immune dysfunction (P < 0.0001 and P = 0.0004, respectively).

CONCLUSIONS

Cryoimmunotherapy significantly increased OS in metastatic pancreatic cancer. Multiple cryoablations and normal pretreatment immunologic function were associated with better prognosis.

SL-01, an oral derivative of gemcitabine, inhibited human breast cancer growth through induction of apoptosis

SL-01 is an oral derivative of gemcitabine that was synthesized by introducing the moiety of 3-(dodecyloxycarbonyl) pyrazine-2-carbonyl at N4-position on cytidine ring of gemcitabine. We aimed to evaluate the efficacy of SL-01 on human breast cancer growth. SL-01 significantly inhibited MCF-7 proliferation as estimated by colorimetric assay. Flow cytometry assay indicated the apoptotic induction and cell cycle arrest in G1 phase. SL-01 modulated the expressions of p-ATM, p53 and p21 and decrease of cyclin D1 in MCF-7 cells. Further experiments were performed in a MCF-7 xenografts mouse model. SL-01 by oral administration strongly inhibited MCF-7 xenografts growth. This effect of SL-01 might arise from its roles in the induction of apoptosis. Immunohistochemistry assay showed the increase of TUNEL staining cells. Western blotting indicated the modulation of apoptotic proteins in SL-01-treated xenografts. During the course of study, there was no evidence of toxicity to mice. In contrast, the decrease of neutrophil cells in peripheral and increase of AST and ALT levels in serum were observed in the gemcitabine-treated mice.

CONCLUSION

SL-01 possessed similar activity against human breast cancer growth with gemcitabine, whereas, with lower toxicity to gemcitabine. SL-01 is a potent oral agent that may supplant the use of gemcitabine.

Targeting the yin and the yang: combined inhibition of the tyrosine kinase c-Src and the tyrosine phosphatase SHP-2 disrupts pancreatic cancer signaling and biology in vitro and tumor formation in vivo

OBJECTIVES

Although c-Src (Src) has emerged as a potential pancreatic cancer target in preclinical studies, Src inhibitors have not demonstrated a significant therapeutic benefit in clinical trials. The objective of these studies was to examine the effects of combining Src inhibition with inhibition of the protein tyrosine phosphatase SHP-2 in pancreatic cancer cells in vitro and in vivo.

METHODS

SHP-2 and Src functions were inhibited by siRNA or small molecule inhibitors. The effects of dual Src/SHP-2 functional inhibition were evaluated by Western blot analysis of downstream signaling pathways; cell biology assays to examine caspase activity, viability, adhesion, migration, and invasion in vitro; and an orthotopic nude mouse model to observe pancreatic tumor formation in vivo.

RESULTS

Dual targeting of Src and SHP-2 induces an additive or supra-additive loss of phosphorylation of Akt and ERK-1/2 and corresponding increases in expression of apoptotic markers, relative to targeting either protein individually. Combinatorial inhibition of Src and SHP-2 significantly reduces viability, adhesion, migration, and invasion of pancreatic cancer cells in vitro and tumor formation in vivo, relative to individual Src/SHP-2 inhibition.

CONCLUSIONS

These data suggest that the antitumor effects of Src inhibition in pancreatic cancer may be enhanced through simultaneous inhibition of SHP-2.

Differences in transcript levels of ABC transporters between pancreatic adenocarcinoma and nonneoplastic tissues

OBJECTIVES

The aim of this study was to evaluate transcript levels of all 49 human ATP-binding cassette transporters (ABCs) in one of the most drug-resistant cancers, namely, the pancreatic ductal adenocarcinoma (PDAC). Association of ABCs levels with clinical-pathologic characteristics and KRAS mutation status was followed as well.

METHODS

Tumors and adjacent nonneoplastic tissues were obtained from 32 histologically verified PDAC patients. The transcript profile of ABCs was assessed using quantitative real-time polymerase chain reaction with a relative standard curve. KRAS mutations in exon 2 were assessed by high-resolution melting analysis and sequencing.

RESULTS

Most ABCs were deregulated in PDAC and 10 ABCs were associated with clinical-pathologic characteristics. KRAS mutations did not change the global expression profile of ABCs.

CONCLUSIONS

The expression of ABC transporters was significantly deregulated in PDAC tumors when compared to nonmalignant tissues. The observed up-regulation of ABCB4, ABCB11, ABCC1, ABCC3, ABCC5, ABCC10, and ABCG2 in tumors may contribute to the generally poor treatment response of PDAC. The up-regulation of ABCA1, ABCA7, and ABCG1 implicates a serious impairment of cellular cholesterol homeostasis in PDAC. On the other hand, the observed down-regulation of ABCA3, ABCC6, ABCC7, and ABCC8 suggests a possible role of stem cells in the development and progression of PDAC.

Hyper-O-GlcNAcylation is anti-apoptotic and maintains constitutive NF-κB activity in pancreatic cancer cells

Cancer cell metabolic reprogramming includes a shift in energy production from oxidative phosphorylation to less efficient glycolysis even in the presence of oxygen (Warburg effect) and use of glutamine for increased biosynthetic needs. This necessitates greatly increased glucose and glutamine uptake, both of which enter the hexosamine biosynthetic pathway (HBP). The HBP end product UDP-N-acetylglucosamine (UDP-GlcNAc) is used in enzymatic post-translational modification of many cytosolic and nuclear proteins by O-linked β-N-acetylglucosamine (O-GlcNAc). Here, we observed increased HBP flux and hyper-O-GlcNAcylation in human pancreatic ductal adenocarcinoma (PDAC). PDAC hyper-O-GlcNAcylation was associated with elevation of OGT and reduction of the enzyme that removes O-GlcNAc (OGA). Reducing hyper-O-GlcNAcylation had no effect on non-transformed pancreatic epithelial cell growth, but inhibited PDAC cell proliferation, anchorage-independent growth, orthotopic tumor growth, and triggered apoptosis. PDAC is supported by oncogenic NF-κB transcriptional activity. The NF-κB p65 subunit and upstream kinases IKKα/IKKβ were O-GlcNAcylated in PDAC. Reducing hyper-O-GlcNAcylation decreased PDAC cell p65 activating phosphorylation (S536), nuclear translocation, NF-κB transcriptional activity, and target gene expression. Conversely, mimicking PDAC hyper-O-GlcNAcylation through pharmacological inhibition of OGA suppressed suspension culture-induced apoptosis and increased IKKα and p65 O-GlcNAcylation, accompanied by activation of NF-κB signaling. Finally, reducing p65 O-GlcNAcylation specifically by mutating two p65 O-GlcNAc sites (T322A and T352A) attenuated the induction of PDAC cell anchorage-independent growth. Our data indicate that hyper-O-GlcNAcylation is anti-apoptotic and contributes to NF-κB oncogenic activation in PDAC.

GSK-3α promotes oncogenic KRAS function in pancreatic cancer via TAK1-TAB stabilization and regulation of noncanonical NF-κB

Mutations in KRAS drive the oncogenic phenotype in a variety of tumors of epithelial origin. The NF-κB transcription factor pathway is important for oncogenic RAS to transform cells and to drive tumorigenesis in animal models. Recently, TGF-β-activated kinase 1 (TAK1), an upstream regulator of IκB kinase (IKK), which controls canonical NF-κB signaling, was shown to be important for chemoresistance in pancreatic cancer and for regulating KRAS-mutant colorectal cancer cell growth and survival. Here, we show that mutant KRAS upregulates glycogen synthase kinase 3α (GSK-3α), leading to its interaction with TAK1 to stabilize the TAK1-TAB complex to promote IKK activity. In addition, GSK-3α is required for promoting critical noncanonical NF-κB signaling in pancreatic cancer cells. Pharmacologic inhibition of GSK-3 suppresses growth of human pancreatic tumor explants, consistent with the loss of expression of oncogenic genes such as c-myc and TERT. These data identify GSK-3α as a key downstream effector of oncogenic KRAS via its ability to coordinately regulate distinct NF-κB signaling pathways.

Radical treatment of stage IV pancreatic cancer by the combination of cryosurgery and iodine-125 seed implantation

AIM: To investigate the therapeutic effect of radical treatment and palliative treatment in stage IV pancreatic cancer patients.

METHODS: 81 patients were enrolled in the study. Radical treatment was performed on 51 patients, while 30 patients were put under palliative treatment. The procedural safety and interval survival for stage IV pancreatic cancer (IS-IV) was assessed by almost 2.5 years of follow-ups. The IS-IV of patients under the two kinds of treatment, and the effects of treatment timing and frequency on IS-IV, were compared.

RESULTS: The IS-IV of patients who received radical treatment was significantly longer than those who received palliative treatment (P < 0.001). The IS-IV of patients who received delayed radical or palliative treatment was longer than those who received accordingly timely treatment (P = 0.0034 and 0.0415, respectively). Multiple treatments can play an important role in improving the IS-IV of patients who received radical treatment (P = 0.0389), but not for those who received palliative treatment (P = 0.99).

CONCLUSION: The effect of radical treatment was significantly more obvious than that of palliative treatment, and multiple radical treatments may contribute more to patients than a single radical treatment.

Systemic therapies for pancreatic cancer--the role of pharmacogenetics

Effective systemic treatment of pancreatic cancer remains a major challenge, with progress hampered by drug resistance and treatment related toxicities. Currently available cytotoxic agents as monotherapy or in combination have provided only a modest survival benefit for patients with advanced disease. Disappointing phase III results with gemcitabine-based combinations in patients with advanced pancreatic cancer might be related to poor efficacy of systemic therapies in unselected patients. Future research strategies should prioritize identification of predictive markers through pharmacogenetic investigations. The individualization of patient treatment through pharmacogenetics may help to improve outcome by maximizing efficacy whilst lowering toxicity. This review provides an update on the pharmacogenetics of pancreatic cancer treatment and its influence on treatment benefits and toxicity.

Systemic therapies for pancreatic cancer--the role of pharmacogenetics

Effective systemic treatment of pancreatic cancer remains a major challenge, with progress hampered by drug resistance and treatment related toxicities. Currently available cytotoxic agents as monotherapy or in combination have provided only a modest survival benefit for patients with advanced disease. Disappointing phase III results with gemcitabine-based combinations in patients with advanced pancreatic cancer might be related to poor efficacy of systemic therapies in unselected patients. Future research strategies should prioritize identification of predictive markers through pharmacogenetic investigations. The individualization of patient treatment through pharmacogenetics may help to improve outcome by maximizing efficacy whilst lowering toxicity. This review provides an update on the pharmacogenetics of pancreatic cancer treatment and its influence on treatment benefits and toxicity.

NF-κB as a target for pancreatic cancer therapy

INTRODUCTION

Pancreatic cancer is the fourth leading cause of adult cancer mortality in the USA. It represents one of the greatest challenges in cancer treatment. The NF-κB transcriptional factors are constitutively activated in the majority of pancreatic cancers and are involved in the regulation of numerous aspects of tumor development and progression. NF-κB and the signaling cascades that regulate its activity have thus become attractive targets for novel therapeutic approaches for pancreatic cancer.

AREAS COVERED

This review describes and discusses the most important advances in the comprehension of the complex molecular biology of NF-κB, as well as the development of novel NF-κB-targeting strategies for the treatment of pancreatic cancer.

EXPERT OPINION

Although the inhibition of NF-κB, especially when combined with more classic chemotherapeutic drugs, could be a promising therapeutic strategy, direct targeting NF-κB still faces important challenges. In the future, targeting nonredundant cytosolic mediators of the activation of NF-κB - such as TNF receptor associated factor family member-associated NF-κB activator -binding kinase 1 (TBK1) and TGF-beta activated kinase 1 (TAK1) - could represent a better approach to inhibit key processes in pancreatic tumor cells and make a difference for this devastating disease.

Potential use of the anti-inflammatory drug, sulfasalazine, for targeted therapy of pancreatic cancer

Pancreatic cancer is an aggressive, drug-resistant disease; its first-line chemotherapeutic, gemcitabine, is only marginally effective. Intracellular depletion of glutathione, a major free-radical scavenger, has been associated with growth arrest and reduced drug resistance (chemosensitization) of cancer cells. In search of a new therapeutic approach for pancreatic cancer, we sought to determine whether specific inhibition of the plasma membrane x(c) (-) cystine transporter could lead to reduced uptake of cysteine, a key precursor of glutathione, and subsequent glutathione depletion. Sulfasalazine (approximately 0.2 mmol/L), an anti-inflammatory drug with potent x(c) (-)-inhibitory properties, markedly reduced l¹⁴C]-cystine uptake, glutathione levels, and growth and viability of human MIA PaCa-2 and PANC-1 pancreatic cancer cells in vitro. These effects were shown to result primarily from inhibition of cystine uptake mediated by the x(c) (-) cystine transporter and not from inhibition of nuclear factor kappaB activation, another property of sulfasalazine. The efficacy of gemcitabine could be markedly enhanced by combination therapy with sulfasalazine both in vitro and in immunodeficient mice carrying xenografts of the same cell lines. No major side effects were observed in vivo.The results of the present study suggest that the x(c) (-) transporter plays a major role in pancreatic cancer by sustaining or enhancing glutathione biosynthesis, and as such, represents a potential therapeutic target. Sulfasalazine, a relatively nontoxic drug approved by the U.S. Food and Drug Administration, may, in combination with gemcitabine, lead to more effective therapy of refractory pancreatic cancer.

Loss of tyrosine phosphatase-dependent inhibition promotes activation of tyrosine kinase c-Src in detached pancreatic cells

Despite an intense focus on novel therapeutic strategies, pancreatic adenocarcinoma remains one of the deadliest human malignancies. The frequent and rapid mortality associated with pancreatic cancer may be attributed to several factors, including late diagnosis, rapid tumor invasion into surrounding tissues, and formation of distant metastases. Both local invasion and metastasis require disruption of tumor cell contacts with the extracellular matrix. Detachment of normal cells from the extracellular matrix leads to a form of programmed cell death termed anoikis. Pancreatic cancer cells avert anoikis by activation of signaling pathways that allow for adhesion-independent survival. In the present studies, cellular signaling pathways activated in detached pancreatic cancer cells were examined. We demonstrate a rapid and robust activation of Src kinase in detached pancreatic cancer cells, relative to adherent. Src autophosphorylation rapidly returned to baseline levels upon reattachment to tissue culture plastic, in the presence or absence of specific extracellular matrix proteins. Treatment of pancreatic cancer cells with tyrosine phosphatase inhibitors increased steady-state Src autophosphorylation in adherent cells and abrogated the detachment-induced increase in Src autophosphorylation. Src was found to co-immunoprecipitate with the Src homology 2 (SH2) domain containing protein tyrosine phosphatase (SHP-2) in pancreatic cancer cells, suggesting that SHP-2 may participate in regulation of Src autophosphorylation in adherent cells. Src family kinase (SFK) dependent increases in Akt and Jun N-terminal kinase (JNK) phosphorylation were observed in detached cells, indicating the potential for Src-dependent activation of survival and stress pathways in pancreatic cancer cells that have detached from the extracellular matrix.

Image-guided stereotactic radiosurgery for locally advanced pancreatic adenocarcinoma results of first 85 patients

BACKGROUND

Locally advanced unresectable pancreatic adenocarcinoma is characterized by poor survival despite chemotherapy and conventional radiation therapy (RT). Recent advances in real-time image-guided stereotactic radiosurgery (SRS) have made it possible to treat these cancers in two to four fractions followed by systemic chemotherapy.

AIMS

The aims of this study includes the following: (1) obtain local control of the disease; (2) improve the survival of these unresectable patients; (3) evaluate the toxicity of SRS; and (4) report results of the largest series from a single center.

METHODS

Pancreatic SRS involves delivery of high doses of accurately targeted radiation given non-invasively in two to four fractions. We treated 85 consecutive patients with locally advanced and recurrent pancreatic adenocarcinoma from February 2004 to November 2009. Age range: 36-88 years, median 66 years; sex: 50 males, 35 females; race: 79 Caucasian, five African American, one Asian; histology: 80 adenocarcinoma, three islet cell, two other. Pre-SRS staging: T(3-4) 85; N(+) 16, N(x) 57, N(0) 12; M(0) 64, M(1) 21. All patients were unresectable at the time of SRS. Seventy-one had no prior surgical resection, and 14 had local recurrence after prior surgical resection. Twenty-nine patients had progression of disease after prior conventional RT. Location of the tumor: head, 57; body and tail, 28. Pre-SRS chemotherapy was given in 48 patients. All patients received gemcitabine-based chemotherapy regimen after SRS. Median tumor volume was 60 cm(3). PET/CT scans done in 55 patients were positive in 52 and negative in three patients. Average maximum standard uptake value was 6.9. Pain score on a scale of 1-10 was: 0-3 in 54, 4-7 in 18, and 8-10 in 13 patients. SRS doses ranged from 15 to 30 Gy with a mean dose of 25.5 Gy delivered in 3 days divided in equal fractions. Mean conformality index was 1.6, and mean isodose line was 80%.

RESULTS

Tumor control: complete, partial, and stable disease were observed in 78 patients for the duration of 3-36 months with median of 8 months. Pain relief was noted in majority of patients lasting for 18-24 weeks. Most of the patients died of distant disease progression while their primary tumor was controlled. Overall median survival from diagnosis was 18.6 months and from SRS it was 8.65 months. For the group of 35 patients with adenocarcinoma without prior surgical resection or RT and no distant metastases, the average and 1-year survival from diagnosis was 15 months and 50%, respectively, and from SRS it was 11.15 months and 30.5%, respectively.

TOXICITY

A total of 19 (22.37%) patients developed grades III/IV GI toxicity including duodenitis, 12 (14.1%); gastritis, 11 (12.9%); diarrhea, three (3.5%); and renal failure was noted in one (1.2%). Three patient had both gastritis and duodenitis. Toxicity was significantly more prevalent in the first 40 patients compared with the last 45 patients (32.5 vs 13.9%).

CONCLUSIONS

SRS for unresectable pancreatic carcinoma can be delivered in three fractions with minimal morbidity and a local tumor control rate of 91.7%. The survival is comparable or better than the reported results for advanced pancreatic cancer, specifically for the group of previously untreated patients with unresectable tumors. Development of distant metastases remains a significant factor.

Palliative chemotherapy for pancreatic malignancies

Metastatic pancreatic cancer is often one of the most challenging malignancies a medical oncologist faces. Although the primary endpoint of many studies remains overall survival, palliation and quality of life are now more commonly being addressed. The author discusses the most common chemotherapeutic modalities for the treatment of metastatic pancreatic cancer, such as single agent chemotherapy, combination therapy, targeted therapy, and second line treatment.

Antiproliferative activity, mechanism of action and oral antitumor activity of CP-4126, a fatty acid derivative of gemcitabine, in in vitro and in vivo tumor models

Gemcitabine is a deoxycytidine (dCyd) analog with activity in leukemia and solid tumors, which requires phosphorylation by deoxycytidine kinase (dCK). Decreased membrane transport is a mechanism of resistance to gemcitabine. In order to facilitate gemcitabine uptake and prolong retention in the cell, a lipophilic pro-drug was synthesized (CP-4126), with an elaidic fatty acid esterified at the 5'position. CP-4126 was tested in cell lines resistant to cytarabine, another dCyd analog or gemcitabine. Activity of gemcitabine and the derivative was comparable in the parent cell lines, while in dCK deficient cells all compounds were inactive. However, inhibition of nucleoside transport increased the IC(50) for gemcitabine up to 200-fold, but not for CP-4126, underlining the independence of a nucleoside transporter. For in vivo evaluation, nude mice bearing a human xenograft were treated intraperitoneally every third day for five doses at the maximal tolerated dose. In melanoma, sarcoma, lung, prostate, pancreatic and breast cancer xenografts, gemcitabine and CP-4126 were equally and highly effective; in four other xenografts moderately but equally active. In contrast to gemcitabine, CP-4126 could be administered orally, with a schedule and dose dependent toxicity and antitumor activity. In a colon cancer xenograft, antitumor activity of orally administered CP-4126 was equal to the intraperitoneally administered drug. In conclusion, CP-4126 is membrane transporter independent. Intraperitoneally administered CP-4126 was as effective as gemcitabine in several xenografts and CP-4126 is tolerated when orally administered. CP-4126 seems to be a promising new anticancer drug.

Secreted interleukin-1alpha induces a metastatic phenotype in pancreatic cancer by sustaining a constitutive activation of nuclear factor-kappaB

Transcription factor nuclear factor-kappaB (NF-kappaB) is constitutively activated in most pancreatic cancer tissues and cell lines but not in normal pancreas nor in immortalized/nontumorigenic human pancreatic ductal epithelial cells. Inhibition of constitutive NF-kappaB activation in pancreatic cancer cell lines suppresses tumorigenesis and tumor metastasis. Recently, we identified autocrine secretion of proinflammatory cytokine interleukin (IL)-1alpha as the mechanism of constitutive NF-kappaB activation in metastatic pancreatic cancer cell lines. However, the role of IL-1alpha in determining the metastatic potential of pancreatic tumor remains to be further investigated. In the current study, we stably expressed IL-1alpha in the nonmetastatic, IL-1alpha-negative MiaPaCa-2 cell lines. Our results showed that the secretion of IL-1alpha in MiaPaCa-2 cells constitutively activated NF-kappaB and increased the expression of NF-kappaB downstream genes involved in the different steps of the metastatic cascade, such as urokinase-type plasminogen activator, vascular endothelial growth factor, and IL-8. MiaPaCa-2/IL-1alpha cells showed an enhanced cell invasion in vitro compared with parental MiaPaCa-2 cells and induced liver metastasis in an orthotopic mouse model. The metastatic phenotype induced by IL-1alpha was inhibited by the expression of phosphorylation-defective IkappaB (IkappaB S32, 36A), which blocked NF-kappaB activation. Consistently, silencing the expression of IL-1alpha by short hairpin RNA in the highly metastatic L3.6pl pancreatic cancer cells completely suppressed their metastatic spread. In summary, these findings showed that IL-1alpha plays key roles in pancreatic cancer metastatic behavior through the constitutive activation of NF-kappaB. Our findings further support the possible link between inflammation and cancer and suggest that IL-1alpha may be a potential therapeutic target for treating pancreatic adenocarcinoma.

Gene expression profiling of adenosine triphosphate-binding cassette transporters in response to K-ras activation and hypoxia in human pancreatic cancer cell cultures

OBJECTIVES

Pancreatic cancer (PC) is hypoxic and highly resistant to conventional chemotherapy. We sought to determine whether K-ras oncogene and/or hypoxia can induce expression of drug resistance-promoting adenosine triphosphate-binding cassette (ABC) transporters in human PC cell lines.

METHODS

Immortalized near-normal human pancreatic ductal epithelial(HPDE) cells, HPDE cells expressing K-rasG12V oncogene, and PCcell lines (MIA PaCa-2, PANC-1, BxPC-3) were subjected to hypoxia and examined for messenger RNA expression of 48 ABC transporters.

RESULTS

Mutant K-ras activation and/or hypoxia of HPDE cells led to induction of various ABC transporters. In the case of PC cell lines, no clear correlation was found between expression of constitutively active K-ras and global ABC transporter expression. Moreover, hypoxic treatment of PC cell lines had different effects on ABC transporter expression.Importantly, PC cell lines did not express the multidrug resistance 1 ABC transporter, a major mechanism of drug resistance. However, multi drug resistance 1 expression in the cells was up-regulated in response to continuous exposure to low doses of vincristine, indicating that drug resistance could be induced.

CONCLUSIONS

Expression of K-ras oncogene and hypoxia, as well as exposure to drugs, can contribute to drug resistance in PC cells.

The xc- cystine/glutamate antiporter: a mediator of pancreatic cancer growth with a role in drug resistance

The x_c⁻ cystine transporter enhances biosynthesis of glutathione, a tripeptide thiol important in drug resistance and cellular defense against oxidative stress, by enabling cellular uptake of cystine, a rate-limiting precursor. Because it is known to regulate glutathione levels and growth of various cancer cell types, and is expressed in the pancreas, we postulate that it is involved in growth and drug resistance of pancreatic cancer. To examine this, we characterised expression of the x_c⁻ transporter in pancreatic cancer cell lines, MIA PaCa-2, PANC-1 and BxPC-3, as subjected to cystine-depletion and oxidative stress. The results indicate that these cell lines depend on x_c⁻-mediated cystine uptake for growth, as well as survival in oxidative stress conditions, and can modulate x_c⁻ expression to accommodate growth needs. Immunohistochemical analysis showed that the transporter was differentially expressed in normal pancreatic tissues and overexpressed in pancreatic cancer tissues from two patients. Furthermore, gemcitabine resistance of cells was associated with elevated x_c⁻ expression and specific x_c⁻ inhibition by monosodium glutamate led to growth arrest. The results suggest that the x_c⁻ transporter by enhancing glutathione biosynthesis plays a major role in pancreatic cancer growth, therapy resistance and represents a potential therapeutic target for the disease.