Drug-resistant Pancreatic Cancer Cells Research Articles

Drug resistant pancreatic cancer cells exhibit altered biophysical interactions with stromal fibroblasts in imaging studies of 3D co-culture models

Interactions between tumor and stromal cells are well known to play prominent roles in progression of pancreatic ductal adenocarcinoma (PDAC). As knowledge of stromal crosstalk in PDAC has evolved, it has become clear that cancer associated fibroblasts can play both tumor promoting and tumor suppressive roles through a combination of paracrine crosstalk and juxtacrine interactions involving direct physical contact. Another major contributor to dismal survival statistics for PDAC is development of resistance to chemotherapy drugs, though less is known about how the acquisition of chemoresistance impacts upon tumor-stromal crosstalk. Here, we use time lapse imaging and image analysis to study how co-culture geometry impacts interactions between epithelial and stromal cells. We show that extracellular matrix (ECM) overlay cultures in which stromal cells (pancreatic stellate cells, or normal human fibroblasts) are placed adjacent to PDAC cells (PANC1) result in direct heterotypic cell adhesions accompanied by dramatic fibroblast contractility. We analyze these interactions in co-cultures using particle image velocimetry (PIV) analysis to quantify cell velocities over the course of time lapse movie sequences. We further contrast co-cultures of PANC1 with those containing a drug resistant subline (PANC1-OR) previously established in our lab and find that heterotypic cell–cell interactions are suppressed in the latter relative to the parental line. We use RNA-seq and bioinformatics analysis to identify differential gene expression in PANC1 and PANC1-OR, which shows that negative regulation of cell adhesion molecules, consistent with increased epithelial mesenchymal transition (EMT), is also correlated with reduction in the hetrotypic cell–cell contact necessary for the contractile behavior observed in drug naïve cultures. Overall these findings elucidate the role of drug-resistance in inhibiting an avenue of stromal crosstalk which is associated with tumor suppression and also help to establish cell culture conditions useful for further mechanistic investigation.

Drug resistant pancreatic cancer cells exhibit altered biophysical interactions with stromal fibroblasts in imaging studies of 3D co-culture models.

Interactions between tumor and stromal cells are well known to play a prominent roles in progression of pancreatic ductal adenocarcinoma (PDAC). As knowledge of stromal crosstalk in PDAC has evolved, it has become clear that cancer associated fibroblasts can play both tumor promoting and tumor suppressive roles through a combination of paracrine crosstalk and juxtacrine interactions involving direct physical contact. Another major contributor to dismal survival statistics for PDAC is development of resistance to chemotherapy drugs. Though less is known about how the acquisition of chemoresistance impacts upon tumor-stromal crosstalk. Here, we use 3D co-culture geometries to recapitulate juxtacrine interactions between epithelial and stromal cells. In particular, extracellular matrix (ECM) overlay cultures in which stromal cells (pancreatic stellate cells, or normal human fibroblasts) are placed adjacent to PDAC cells (PANC1), result in direct heterotypic cell adhesions accompanied by dramatic fibroblast contractility which leads to highly condensed macroscopic multicellular aggregates as detected using particle image velocimetry (PIV) analysis to quantify cell velocities over the course of time lapse movie sequences. To investigate how drug resistance impacts these juxtacrine interactions we contrast cultures in which PANC1 are substituted with a drug resistant subline (PANC1-OR) previously established in our lab. We find that heterotypic cell-cell interactions are highly suppressed in drug-resistant cells relative to the parental PANC1 cells. To investigate further we conduct RNA-seq and bioinformatics analysis to identify differential gene expression in PANC1 and PANC1-OR, which shows that negative regulation of cell adhesion molecules, consistent with increased epithelial mesenchymal transition (EMT), is also consistent with loss of hetrotypic cell-cell contact necessary for the contractile behavior observed in drug naïve cultures. Overall these findings elucidate the role of drug-resistance in inhibiting an avenue of stromal crosstalk which is associated with tumor suppression and also help to establish cell culture conditions useful for further mechanistic investigation.

3D Chemical Imaging by Fluorescence-detected Mid-Infrared Photothermal Fourier Light Field Microscopy.

Three-dimensional molecular imaging of living organisms and cells plays a significant role in modern biology. Yet, current volumetric imaging modalities are largely fluorescence-based and thus lack chemical content information. Mid-infrared photothermal microscopy as a chemical imaging technology provides infrared spectroscopic information at submicrometer spatial resolution. Here, by harnessing thermosensitive fluorescent dyes to sense the mid-infrared photothermal effect, we demonstrate 3D fluorescence-detected mid-infrared photothermal Fourier light field (FMIP-FLF) microscopy at the speed of 8 volumes per second and submicron spatial resolution. Protein contents in bacteria and lipid droplets in living pancreatic cancer cells are visualized. Altered lipid metabolism in drug-resistant pancreatic cancer cells is observed with the FMIP-FLF microscope.

Priming of pancreatic cancer cells with bispecific antibody armed activated T cells sensitizes tumors for enhanced chemoresponsiveness

ABSTRACT In this study, we investigated the ability of bispecific antibody armed activated T cells to target drug resistant pancreatic cancer cells and whether or not “priming” these resistant cancer cells with bispecific antibody armed activated T cells could enhance subsequent responsiveness to chemotherapeutic drugs. Chemotherapeutic responses for pancreatic cancer are either limited or the tumors develop resistance to chemotherapy regimens. The impetus for this study was the remarkable clinical response seen in our earlier phase I/II clinical trial: a pancreatic cancer patient with drug resistant tumors who showed progression of disease following three infusions of anti-CD3 x anti-EGFR bispecific antibody armed activated T cells (EGFR BATs) was restarted on the initial low dose of 5-fluorouracil showed complete response, suggesting that BATs infusions may have sensitized patient’s tumor for chemoresponsiveness. In the current study, we tested the hypothesis that BATs can sensitize tumors for chemoresponsiveness. Gemcitabine or cisplatin-resistant MiaPaCa-2 and L3.6 cell lines were effectively targeted by EGFR BATs. Priming of drug sensitive or resistant cells with EGFR BATs followed by retargeting with lower concentrations of 50% inhibitory concentration of gemcitabine or cisplatin showed enhanced cytotoxicity. Gemcitabine or cisplatin-resistant cell lines show an increased proportion of CD44+/CD24+/EpCAM+ cancer stem like cells as well as an increased number of ABC transporter ABCG2 positive cells compared to the parental cell lines. These data suggest that bispecific antibody armed activated T cells can target and kill chemo-resistant tumor cells and also markedly augment subsequent chemotherapeutic responsiveness, possibly by modulating the expression of ABC transporters.

Emodin Reverses Gemcitabine Resistance of Pancreatic Cancer Cell Lines Through Inhibition of IKKβ/NF-κB Signaling Pathway.

BackgroundPancreatic cancer is one of the most malignant tumors, and gemcitabine has been considered as the standard treatment and been widely utilized as a first-line drug for advanced pancreatic cancer, but gemcitabine-resistance always occurs after a short period of treatment.MethodsTwo pancreatic cancer cell lines Panc-1 and MIA-PaCa-2 were used as the study subject and their gemcitabine-resistant cells were established. Both drug-resistant cells were divided into four groups: blank, emodin, gemcitabine, and emodin+gemcitabine. Cell viability was detected by MTT assay. Flow cytometry was performed to detect cell apoptosis rate and P-gp function. Quantitative real-time polymerase chain reaction and Western blotting were used to detect Survivin, XIAP, Caspase-9/3, NF-κB p65, IKKβ and IκB-α mRNA/protein expressions, respectively. Electrophoretic mobility shift assay (EMSA) was performed to detect NF-κB binding activity. Rhodamine 123 efflux assay was used to detect P-gp function.ResultsEmodin could inhibit cell activity in all cell lines. Both emodin and gemcitabine can significantly increase the apoptosis rate, and the combination of the two drugs can further significantly increase the apoptosis rate in normal pancreatic cancer cell lines. In both drug-resistant pancreatic cancer cell lines, it can be observed that although gemcitabine can increase the apoptosis rate, the effect of promoting apoptosis is significantly lower than that of emodin; the drug combination can still significantly increase the apoptosis rate on the basis of emodin alone. Emodin can significantly reduce the mRNA and protein expression levels of Survivin, XIAP, NF-κB, and IKKβ, and significantly increase the mRNA and protein expression levels of Caspase-3/9 and IκB-α. Emodin significantly reduced NF-κB activity and emodin significantly promoted P-gp fluorescence intensity from Rhodamine 123 efflux assay.ConclusionEmodin inhibits the expression of IKKβ, thereby inhibiting the expression and activity of downstream NF-κB, and inhibits P-gp function at the same time, ultimately achieving the purpose of reversing the drug-resistance of pancreatic cancer cell lines.

Abstract B67: Stroma breaking dual targeted theranostic nanoparticles for image-guided and targeted therapy of pancreatic cancer

Abstract Low efficiency in drug delivery into pancreatic cancer cells due to the presence of a dense fibrotic tumor stromal barrier has been the major unmet clinical challenge for pancreatic cancer treatment. Drug delivery stromal barriers include irregular and insufficient tumor blood vessels, extensive fibroblasts, massive infiltration of tumor associated macrophages, and enriched fibrous stromal matrix. Building upon our understanding of pancreatic cancer biology and expertise in developing theranostic nanoparticles, we have developed a stroma breaking drug delivery nanoparticle platform with dual receptor targeting ability and protease activity for overcoming the above stromal barriers. Targeting urokinase plasminogen activator receptor (uPAR) that is expressed in angiogenic tumor endothelial cells, tumor stromal fibroblasts and macrophages, and invasive tumor cells facilitates nanoparticle extravasation, retention, intratumoral distribution and internalization into tumor stromal and pancreatic cancer cells. Co-targeting IGF-IR that is uniformly expressed at a very high level in all tumor cells as well as an intermediate level in tumor stromal cells enhances nanoparticle-drug delivery into drug resistant pancreatic cancer cells. Interactions of dual receptor targeted IONPs with uPAR and IGF-1R expressing tumor fibroblasts and macrophages ensure retention of the nanoparticles in the tumor stroma while MMP14 catalytic activity of the uPAR-targeting ATFMMP14 ligand breaks down the extracellular matrix and facilitates the migration of IONPs through the tumor stroma to reach cancer cells. Additionally, internalization of theranostic IONPs into tumor stromal cells leads to the stromal collapse and further enhances nanoparticle delivery into tumor cells. This dual targeted and protease activate IONP was produced by conjugation of the recombinant amino terminal fragment (ATF) of uPA and catalytic domain of MMP14 fusion ligand and human insulin-like growth factor 1 (IGF-1) to the polymer coating of the same IONP. We found that systemic delivery of the targeted and protease active theranostic IONPs led to the accumulation of significant higher levels of the theranostic IONPs into pancreatic tumors, and marked improvement of intratumoral distribution and tumor cell uptake of the nanoparticle-drug carriers in orthotopic human pancreatic cancer tissue derived xenografts (PDX) models in nude mice. Enhanced intratumoral delivery of theranostic nanoparticles could be detected by non-invasive MRI and optical imaging. Multiphoton microscopy showed the ability of the targeted and MMP14 active theranostic nanoparticles penetrating through the stromal barrier that enriched in collagen fibers and entering into the tumor center following intravenous delivery in mice bearing PDX tumors. As the result of improved nanoparticle-drug delivery, systemic administrations of the dual receptor targeted and MMP14 active theranostic IONPs carrying chemotherapy drug, doxorubicin, produced the strongest anti-tumor growth effect compared to single receptor targeted, uPAR-targeted without MMP14 or non-targeted theranostic IONPs in orthotopic pancreatic cancer PDX models in nude mice. Histological analysis revealed that PDX tumors obtained from the mice that received repeated administrations of the dual receptor targeted MMP14-IONPs-Dox had higher levels of tumor cell death and inhibition of cell proliferation compared to those treated with other targeted and non-targeted theranostic IONPs. Therefore, uPAR and IGF-1R dual targeted and MMP14 active theranostic IONPs provide promising nanoparticle-drug delivery carriers for the development of novel targeted and image-guided therapy for applications of precision oncology for effective treatment of pancreatic cancer. Citation Format: Hongyu Zhou, Xiangxue Guo, Weiping Qian, Fatih M. Uckun, Liya Wang, Y Andrew Wang, Hongyu Chen, David A. Kooby, Malgorzata Lipowska, Charles A. Staley, Lily Yang.{Authors}. Stroma breaking dual targeted theranostic nanoparticles for image-guided and targeted therapy of pancreatic cancer. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2016 May 12-15; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(24 Suppl):Abstract nr B67.

Carbon nanotubes as carriers of Panax ginseng metabolites and enhancers of ginsenosides Rb1 and Rg1 anti-cancer activity

A major benefit to nanomaterial based-medicine is the ability to provide nanosized vehicles for sporadic metabolites. Here, we describe how the conjugation of valuable ginseng secondary metabolites (ginsenoside Rb1 or Rg1) with carbon nanotubes (CNT) can enhance their anti-proliferative and anti-cancer effects. Ginsenoside-CNT conjugate (Rb-CNT or Rg-CNT) permitted the ginsenosides to be used at a low dose, yet achieve a higher incidence of cancer killing. We were able to demonstrate that the ginsenoside-CNT conjugate can decrease cell viability up to 62% in breast cancer cells (MCF-7) and enhance antiproliferation of drug-resistant pancreatic cancer cells (PANC-1) by 61%. The interaction of the ginsenoside-CNT conjugate with breast cancer cells was studied using Raman Spectroscopy mapping. Total transcriptome profiling (Affymetrix platform) of MCF-7 cells treated with the ginsenoside-CNT conjugate shows that a number of cellular, apoptotic and response to stimulus processes were affected. Therefore, our data confirmed the potential use of CNT as a drug delivery system.

Metabolic flux-driven sialylation alters internalization, recycling, and drug sensitivity of the epidermal growth factor receptor (EGFR) in SW1990 pancreatic cancer cells.

In prior work we reported that advanced stage, drug-resistant pancreatic cancer cells (the SW1990 line) can be sensitized to the EGFR-targeting tyrosine kinase inhibitors (TKIs) erlotinib and gefitinib by treatment with 1,3,4-O-Bu3ManNAc (Bioorg. Med. Chem. Lett. (2015) 25(6):1223-7). Here we provide mechanistic insights into how this compound inhibits EGFR activity and provides synergy with TKI drugs. First, we showed that the sialylation of the EGFR receptor was at most only modestly enhanced (by ∼20 to 30%) compared to overall ∼2-fold increase in cell surface levels of this sugar. Second, flux-driven sialylation did not alter EGFR dimerization as has been reported for cancer cell lines that experience increased sialylation due to spontaneous mutations. Instead, we present evidence that 1,3,4-O-Bu3ManNAc treatment weakens the galectin lattice, increases the internalization of EGFR, and shifts endosomal trafficking towards non-clathrin mediated (NCM) endocytosis. Finally, by evaluating downstream targets of EGFR signaling, we linked synergy between 1,3,4-O-Bu3ManNAc and existing TKI drugs to a shift from clathrin-coated endocytosis (which allows EGFR signaling to continue after internalization) towards NCM endocytosis, which targets internalized moieties for degradation and thereby rapidly diminishes signaling.

Abstract 4826: ONC212 exhibits increased cytotoxicity relative to ONC201 in a subset of human pancreatic cancer cell lines

Abstract Pancreatic cancer is one of the most deadly types of cancer with five-year survival rate of ∼6%. This poor prognosis is attributed to aggressive growth of the tumor cells, metastasis at an early stage and resistance to standard chemotherapy. Therefore, finding new treatments and improving outcomes of pancreatic cancer patients have been high priorities. ONC201 is a small molecule that selectively targets a broad range of tumor types tested. It is currently in phase I/II clinical trials for advanced solid, hematopoietic, and lymphoid tumors. The ONC201 analogue, ONC212, is in preclinical development for certain cancers that are not lead indications for the parent compound ONC201. We examined the efficacy of ONC201 and ONC212 in a panel of human pancreatic cancer cell lines. Among seven cell lines tested, three cell lines were relatively insensitive to ONC201, with IC50 values of 100 ìM or greater. However, these cell lines showed greater sensitivity to ONC212 with IC50 values of 31-56 ìM. We compared ONC201-resistant PANC-1 cells and ONC201-sensitive HPAF-II cells. Both ONC201 and ONC212 induced apoptosis in HPAF-II cells, as assessed by PARP cleavage, while PARP cleavage was detected only when PANC-1 cells were treated with ONC212 but not ONC201. We are currently evaluating the efficacy of ONC201 and ONC212 in a panel of patient-derived low passage pancreatic cancer cell lines. We found a correlation between high expression levels of RTKs (c-MET, ALK, EGFR, IGFR, HER2) and decreased sensitivity to ONC201 in pancreatic cancer cell lines. We investigated the effect of ONC201 on EGFR and IGFR, which are highly expressed in PANC-1 and found that ONC201 does not inhibit receptor activation by the specific growth factors. We are studying the effects of ONC201 and ONC212 on RTKs and their signal transduction pathways. Lastly, since aggressive drug-resistant pancreatic cancer cells express high levels of RTKs, we are developing a rationale combining ONC201/ONC212 with specific small molecule RTK inhibitors such as crizotinib or lapatinib. We are exploring these combination treatments using cell lines, organoids and PDX models to unravel specific therapy options for therapy-refractory pancreatic cancer cells. Our goal is to provide the preclinical rationale for clinical trials of ONC201 or ONC212 as mono-agents or in combination with other therapies for pancreatic cancer patients. Citation Format: Avital Lev, Jessica Wagner, David T. Dicker, Martin Stogniew, Joshua E. Allen, Lee Schalop, Wolfgang Oster, Gary L. Olson, Wafik S. El-Deiry. ONC212 exhibits increased cytotoxicity relative to ONC201 in a subset of human pancreatic cancer cell lines. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4826.

Metabolic glycoengineering sensitizes drug-resistant pancreatic cancer cells to tyrosine kinase inhibitors erlotinib and gefitinib.

Metastatic human pancreatic cancer cells (the SW1990 line) that are resistant to the EGFR-targeting tyrosine kinase inhibitor drugs (TKI) erlotinib and gefitinib were treated with 1,3,4-O-Bu3ManNAc, a “metabolic glycoengineering” drug candidate that increased sialylation by ∼12-fold. Consistent with genetic methods previously used to increase EGFR sialylation, this small molecule reduced EGF binding, EGFR transphosporylation, and downstream STAT activation. Significantly, co-treatment with both the sugar pharmacophore and the existing TKI drugs resulted in strong synergy, in essence re-sensitizing the SW1990 cells to these drugs. Finally, l,3,4-O-Bu3ManNAz, which is the azido-modified counterpart to l,3,4-O-Bu3ManNAc, provided a similar benefit thereby establishing a broad-based foundation to extend a “metabolic glycoengineering” approach to clinical applications.

Highlights from Recent Cancer Literature

Highlights from Recent Cancer Literature

Abstract 1747: Biochanin A overcomes gemcitabine resistance in pancreatic cancer cells

Abstract Drug resistance is one of the major reasons for failure of chemotherapy and high mortality rate in pancreatic cancer. Gemcitabine (GEM) and 5-fluorouracil are two drugs which have shown to improve the survival of pancreatic cancer patients but intrinsic or acquired characteristics make this cancer resistant to these drugs. Previously, we have observed that biochanin A (bioA) effectively reduces the survival, signaling and progression of pancreatic cancer cells. In this study, we aim at determining the effect of bioA on drug resistant pancreatic cancer cells. To test our hypothesis, first we compared three pancreatic cancer cells line: Panc1, MiaPaCa2 and AsPC1 for their sensitivity to gemcitabine and protein expressions. We found that Panc1 cells are highly resistant to GEM with IC50 of 75µM while the same for MiaPaCa2 and AsPC1 cells was 0.04µM. Our western blot data show that the levels of NFkappaB, EGFR and CD133 were higher in Panc1 cells compared to other two cell lines suggesting the role of these factors in imparting drug resistant characteristics to pancreatic cancer cells. Our cell survival studies show that bioA is more effective in reducing the survival of Panc1 cells compared to the other two cell lines. Next, we selected GEM resistant cells (AsPC/G) by continuously exposing AsPC1 cells with increasing concentration of GEM. We generated a GEM resistant cell line that was 20-fold resistant to GEM compared to the parent cell line. AsPC/G cells had higher colony formation ability and in vivo tumorigenicity compared to the parent cells. Also, the expression of p-EGFR, NFκB, p-Akt and EMT markers were upregulated in AsPC/G cell compared to AsPC1 cells. We found that bioA was more cytotoxic to AsPC/G cells compared to AsPC1 cells suggesting that bioA affects the molecular mechanisms which impart drug resistant characteristics. To further understand this phenomenon, we analyzed the molecular mechanisms affected by bioA. We observed that bioA reduces the levels of p-EGFR, p-Akt and NFκB in AsPC1 cells. Upregulation of these proteins is known to impart drug resistant characteristics to pancreatic cancer cells; therefore, by inhibiting them, bioA reduces the survival of GEM resistant pancreatic cancer cells. Our study concludes that bioA reduces the survival of GEM resistant pancreatic cancer cells and a treatment regimen with bioA may improve the outcome of chemotherapy in pancreatic cancer patients. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1747. doi:10.1158/1538-7445.AM2011-1747

CNT1 Expression Influences Proliferation and Chemosensitivity in Drug-Resistant Pancreatic Cancer Cells

Overcoming the inherent chemoresistance of pancreatic cancers remains a major goal of therapeutic investigations in this disease. In this study, we discovered a role for the human concentrative nucleoside transporter-1 (hCNT1; SLC28A1), a high-affinity pyrimidine nucleoside transporter, in determining the chemosensitivity of human pancreatic cancer cells to gemcitabine, the drug used presently as a standard of care. Compared with normal pancreas and pancreatic ductal epithelial cells, hCNT1 expression was frequently reduced in pancreatic tumors and tumor cell lines. In addition, hCNT1-mediated (3)H-gemcitabine transport was lower in pancreatic cancer cell lines and correlated with cytotoxic IC(50) estimations of gemcitabine. In contrast to gemcitabine-sensitive pancreatic cancer cell lines, MIA PaCa-2, a gemcitabine-resistant pancreatic cancer cell line, exhibited relatively restrictive, cell cycle-dependent hCNT1 expression and transport. hCNT1 translation was suppressed in the late G1-enriched MIA PaCa-2 cell population possibly in an miRNA-dependent manner, which corresponded with the lowest hCNT1-mediated gemcitabine transport during this phase. Although hCNT1 protein was induced during G1/S transition, increased hCNT1 trafficking resulted in maximal cell surface recruitment and transport-overshoot in the G2/M phase-enriched cell population. hCNT1 protein was directed predominantly to proteasomal or lysosomal degradation in S or G2/M phase MIA PaCa-2 cells, respectively. Pharmacological inhibition of hCNT1 degradation moderately increased cell surface hCNT1 expression and cellular gemcitabine transport in MIA PaCa-2 cells. Constitutive hCNT1 expression reduced clonogenic survival of MIA PaCa-2 cells and steeply augmented gemcitabine transport and chemosensitization. In addition to supporting a putative tumor suppressor role for hCNT1, our findings identify hCNT1 as a potential candidate to render drug-resistant pancreatic cancer cells amenable to chemotherapy.

A novel arylethynyltriazole acyclonucleoside inhibits proliferation of drug-resistant pancreatic cancer cells

Novel arylethynyltriazole acyclonucleosides were synthesized and assessed for their anticancer activity on drug-resistant pancreatic cancer MiaPaCa-2 cells. One lead compound was found to have much more potent apoptosis-related antiproliferative effects than gemcitabine, the current first-line treatment for pancreatic cancer. Further investigations showed that this active compound did not inhibit DNA synthesis, which means that it does not resemble gemcitabine and may involve a different mechanism of action.

N-Aryltriazole ribonucleosides with potent antiproliferative activity against drug-resistant pancreatic cancer

Novel N-aryltriazole nucleosides were synthesized via Cu-mediated C-N cross-coupling reaction starting with 3-aminotriazole ribonucleoside and various boronic acids. Two of them exhibited potent apoptosis-related antiproliferative activity against the drug-resistant pancreatic cancer cell line MiaPaCa-2, with an increased potency compared to gemcitabine, the reference treatment for pancreatic cancer. A preliminary SAR study suggests that the appended N-aryl moiety and the substituent at its para-position, as well as the ribose sugar component, contribute considerably to the observed antiproliferative activity.

Novel Triazole Ribonucleoside Down-Regulates Heat Shock Protein 27 and Induces Potent Anticancer Activity on Drug-Resistant Pancreatic Cancer

A series of novel 3-arylethynyltriazolyl ribonucleosides were synthesized and assessed for their anticancer activity on the drug-resistant pancreatic cancer cell line MiaPaCa-2. Among them, one compound exhibited potent apoptosis-inducing properties and anticancer activity against the pancreatic cancer model MiaPaCa-2 both in vitro and in vivo with no adverse effects. This compound did not inhibit DNA synthesis and therefore does not resemble the clinical drug gemcitabine. It did, however, significantly down-regulate the expression of heat shock protein 27 (Hsp27), a small molecular chaperone playing an important role in drug resistance and highly expressed in drug-resistant cancer forms, and thus represents the first small molecular anticancer lead with such a mode of action.

Synthesis and Cytotoxicity of a New Class of Potent Decapeptide Macrocycles

Described are the syntheses of five decapeptides that are C-2-symmetrical derivatives of the natural product pentapeptide sansalvamide A. Derivatives were made using a succinct convergent synthesis. These analogues share no structural homology to current cancer drugs, are cytotoxic at levels on par with existing drugs treating cancers, and demonstrate selectivity for drug-resistant pancreatic cancer cell lines over noncancerous cell lines. These molecules are excellent chemotherapeutic leads in the search for new anticancer agents.

A pilot study on the impact of the drug resistance on the radioresistance in human pancreatic cancer cell lines

To investigate the impact of the drug resistance on the radioresistance in human pancreatic cancer cell lines. Three drug resistant pancreatic cancer cell sublines induced by fluorouracil (5-FU), adriamycin (ADM) and gemcitabine respectively, SW1990/FU, SW1990/ADM and SW1990/Gz, were tested for the cell cycle and radio-sensitivity with flow cytometry and clonogenic assay. Compared with SW1990, the cell cycle assay indicated higher G(0)/G(1) period percentage in SW1990/FU and SW1990/Gz, but the G(2)/M period percentage decreased; SW1990/FU had the same while SW1990/Gz had lower S period percentage. SW1990/ADM almost had a similar cell cycle with SW1990. Clonogenic assay showed both SW1990/FU and SW1990/Gz had greater survival fraction (SF(2)) than SW1990, but SW1990/ADM had seemingly similar SF(2) as SW1990. Drug resistant pancreatic cancer cell lines have reduced G(2)/M period percentage and increased radioresistance.

Intrinsic Chemoresistance to Gemcitabine Is Associated with Decreased Expression of BNIP3 in Pancreatic Cancer

Although chemotherapy with gemcitabine is a common mode of treatment of pancreatic cancer, 75% of patients do not benefit from this therapy. It is likely that the sensitivity of cancer cells to gemcitabine is determined by a number of different factors. To identify genes that might contribute to resistance to gemcitabine, 15 pancreatic cancer cell lines were subjected to gemcitabine treatment. Simultaneously, gene expression profiling using a cDNA microarray to identify genes responsible for gemcitabine sensitivity was performed. The pancreatic cancer cell lines could be classified into three groups: a gemcitabine "sensitive," an "intermediate sensitive," and a "resistant" group. Microarray analysis identified 71 genes that show differential expression between gemcitabine-sensitive and -resistant cell lines including 27 genes relatively overexpressed in sensitive cell lines whereas 44 genes are relatively overexpressed in resistant cell lines. Among these genes, 7 genes are potentially involved in the phosphatidylinositol 3-kinase/Akt pathway. In addition to this major signaling pathway, Bcl2/adenovirus E1B 19 kDa protein interacting protein (BNIP3), a Bcl-2 family proapoptotic protein, was identified as being expressed at lower levels in drug-resistant pancreatic cancer cell lines. In an analysis of 21 pancreatic cancer tissue specimens, more than 90% showed down-regulated expression of BNIP3. When expression of BNIP3 was suppressed using small interfering RNA, gemcitabine-induced cytotoxicity in vitro was much reduced. These results suggest that BNIP3 and the phosphatidylinositol 3-kinase/Akt pathway may play an important role in the poor response to gemcitabine treatment in pancreatic cancer patients.