Inhibition of AKT2 enhances sensitivity to gemcitabine via regulating PUMA and NF-κB signaling pathway in human pancreatic ductal adenocarcinoma

Wogonin increases gemcitabine sensitivity in pancreatic cancer by inhibiting Akt pathway

Pancreatic cancer has a high degree of malignancy and a low 5-year survival rate, and drug resistance is one of the main factors leading to poor prognosis of pancreatic cancer. Wogonin is a flavonoid drug isolated from Scutellaria baicalensis, which has certain antitumor activity. Hence the purpose of this study was to investigate whether wogonin can be used to enhance the sensitivity of pancreatic cancer to gemcitabine chemotherapy, and investigate its possible sensitization mechanism. In vitro, MTT assay showed that wogonin increased gemcitabine cytotoxicity in gemcitabine-resistant pancreatic cancer cells. In vivo, Wogonin combined with gemcitabine was found to inhibit tumor growth in orthotopic pancreatic cancer mouse model. In order to explore the sensitization mechanism, the differentially expressed genes (DEGs) of the gemcitabine-resistant cell line Panc-1 and the gemcitabine-sensitive cell line Bxpc-3 were screened through the GEO database, and 15 differentially expressed genes were obtained by intersecting with the potential targets of wogonin. Gene Ontology and KEGG enrichment analysis was performed. Bioinformatics results predicted that wogonin promoted pancreatic cancer cell apoptosis by inhibiting protein kinase B (Akt) signaling, thereby enhancing the sensitivity of gemcitabine to Pancreatic cancer. The above results were also verified by flow cytometry and Western blotting experiments. In conclusion, wogonin may enhance the sensitivity of gemcitabine by inhibiting Akt pathway.

3D-Printed Coaxial Hydrogel Patches with Mussel-Inspired Elements for Prolonged Release of Gemcitabine

With the aim of fabricating drug-loaded implantable patches, a 3D printing technique was employed to produce novel coaxial hydrogel patches. The core-section of these patches contained a dopamine-modified methacrylated alginate hydrogel loaded with a chemotherapeutic drug (Gemcitabine), while their shell section was solely comprised of a methacrylated alginate hydrogel. Subsequently, these patches were further modified with CaCO3 cross linker and a polylactic acid (PLA) coating to facilitate prolonged release of the drug. Consequently, the results showed that addition of CaCO3 to the formula enhanced the mechanical properties of the patches and significantly reduced their swelling ratio as compared to that for patches without CaCO3. Furthermore, addition of PLA coating to CaCO3-containing patches has further reduced their swelling ratio, which then significantly slowed down the release of Gemcitabine, to a point where 4-layered patches could release the drug over a period of 7 days in vitro. Remarkably, it was shown that 3-layered and 4-layered Gemcitabine loaded patches were successful in inhibiting pancreatic cancer cell growth for a period of 14 days when tested in vitro. Lastly, in vivo experiments showed that gemcitabine-loaded 4-layered patches were capable of reducing the tumor growth rate and caused no severe toxicity when tested in mice. Altogether, 3D printed hydrogel patches might be used as biocompatible implants for local delivery of drugs to diseased site, to either shrink the tumor or to prevent the tumor recurrence after resection.

TGF-β downregulation overcomes gemcitabine resistance in oral squamous cell carcinoma

OBJECTIVE

The aim of this study was to explore the mechanisms by which oral cancer acquires resistance to gemcitabine.

METHODS

Oral squamous cell carcinoma (OSCC) cells were treated with gemcitabine upon infection or with a lentivirus harboring short hairpin RNA (shRNA) targeted to transforming growth factor-β (TGF-β). Then, Western blot, ELISA, migration assay, MTT assay, and animal experiments were used to explore the mechanism of resistance to gemcitabine treatment.

RESULTS

After the treatment of non-transfected cells with gemcitabine, NF-κB and AKT activities were increased, which may have induced the OSCC resistance to gemcitabine. Then, we found that TGF-β downregulation effectively reduced NF-κB and AKT phosphorylation levels after the administration of gemcitabine and increased the OSCC sensitivity to gemcitabine, resulting in cell death and the blunting of OSCC resistance to gemcitabine. The EMT was also reduced by TGF-β downregulation combined with gemcitabine treatment.

CONCLUSION

Cellular levels of TGF-β constitute an important factor in gemcitabine resistance and TGF-β silencing might represent a novel and potent strategy for overcoming OSCC resistance to gemcitabine.

Noncoding RNAs Associated with Therapeutic Resistance in Pancreatic Cancer

Therapeutic resistance is an inevitable impediment towards effective cancer therapies. Evidence accumulated has shown that the signaling pathways and related factors are fundamentally responsible for therapeutic resistance via regulating diverse cellular events, such as epithelial-to-mesenchymal transition (EMT), stemness, cell survival/apoptosis, autophagy, etcetera. Noncoding RNAs (ncRNAs) have been identified as essential cellular components in gene regulation. The expression of ncRNAs is altered in cancer, and dysregulated ncRNAs participate in gene regulatory networks in pathological contexts. An in-depth understanding of molecular mechanisms underlying the modulation of therapeutic resistance is required to refine therapeutic benefits. This review presents an overview of the recent evidence concerning the role of human ncRNAs in therapeutic resistance, together with the feasibility of ncRNAs as therapeutic targets in pancreatic cancer.

Targeting Autophagy by MPT0L145, a Highly Potent PIK3C3 Inhibitor, Provides Synergistic Interaction to Targeted or Chemotherapeutic Agents in Cancer Cells

Anticancer therapies reportedly promote pro-survival autophagy in cancer cells that confers drug resistance, rationalizing the concept to combine autophagy inhibitors to increase their therapeutic potential. We previously identified that MPT0L145 is a PIK3C3/FGFR inhibitor that not only increases autophagosome formation due to fibroblast growth factor receptor (FGFR) inhibition but also perturbs autophagic flux via PIK3C3 inhibition in bladder cancer cells harboring FGFR activation. In this study, we hypothesized that combined-use of MPT0L145 with agents that induce pro-survival autophagy may provide synthetic lethality in cancer cells without FGFR activation. The results showed that MPT0L145 synergistically sensitizes anticancer effects of gefitinib and gemcitabine in non-small cell lung cancer A549 cells and pancreatic cancer PANC-1 cells, respectively. Mechanistically, drug combination increased incomplete autophagy due to impaired PIK3C3 function by MPT0L145 as evidenced by p62 accumulation and no additional apoptotic cell death was observed. Meanwhile, drug combination perturbed survival pathways and increased vacuolization and ROS production in cancer cells. In conclusion, the data suggest that halting pro-survival autophagy by targeting PIK3C3 with MPT0L145 significantly sensitizes cancer cells to targeted or chemotherapeutic agents, fostering rational combination strategies for cancer therapy in the future.

Targeting Oncogenic Nuclear Factor Kappa B Signaling with Redox-Active Agents for Cancer Treatment

SIGNIFICANCE

Nuclear factor kappa B (NF-κB) signaling is essential under physiologically relevant conditions. However, aberrant activation of this pathway plays a pertinent role in tumorigenesis and contributes to resistance. Recent Advances: The importance of the NF-κB pathway means that its targeting must be specific to avoid side effects. For many currently used therapeutics and those under development, the ability to generate reactive oxygen species (ROS) is a promising strategy.

CRITICAL ISSUES

As cancer cells exhibit greater ROS levels than their normal counterparts, they are more sensitive to additional ROS, which may be a potential therapeutic niche. It is known that ROS are involved in (i) the activation of NF-κB signaling, when in sublethal amounts; and (ii) high levels induce cytotoxicity resulting in apoptosis. Indeed, ROS-induced cytotoxicity is valuable for its capabilities in killing cancer cells, but establishing the potency of ROS for effective inhibition of NF-κB signaling is necessary. Indeed, some cancer treatments, currently used, activate NF-κB and may stimulate oncogenesis and confer resistance.

FUTURE DIRECTIONS

Thus, combinatorial approaches using ROS-generating agents alongside conventional therapeutics may prove an effective tactic to reduce NF-κB activity to kill cancer cells. One strategy is the use of thiosemicarbazones, which form redox-active metal complexes that generate high ROS levels to deliver potent antitumor activity. These agents also upregulate the metastasis suppressor, N-myc downstream regulated gene 1 (NDRG1), which functions as an NF-κB signaling inhibitor. It is proposed that targeting NF-κB signaling may proffer a new therapeutic niche to improve the efficacy of anticancer regimens.

BH3 Mimetic ABT-199 Enhances the Sensitivity of Gemcitabine in Pancreatic Cancer in vitro and in vivo

BACKGROUND AND AIMS

Pancreatic cancer is an aggressive malignancy with poor prognosis. Gemcitabine is the standard chemotherapeutic drug used to treat the disease; however, it has a low response rate. Therefore, there is an urgent need to develop new and safe therapies to enhance sensitivity to gemcitabine in treating pancreatic cancer.

METHODS

The synergistic effect of gemcitabine combined with specific B cell CLL/lymphoma 2 (Bcl-2) inhibitor ABT-199 against pancreatic cancer was tested using cell viability, cell cycle, and apoptosis assays in vitro and in an MIA Paca-2 xenograft model in vivo. Its underlying mechanism was explored using western blotting analysis of Bcl-2 family proteins.

RESULTS

ABT-199 not only enhanced the effect of gemcitabine on cell growth inhibition but also promoted gemcitabine-induced apoptosis in pancreatic cancer cell lines. Gemcitabine decreased the expression of anti-apoptotic protein Mcl-1 but increased the expression of anti-apoptotic protein Bcl-2. ABT-199 downregulated the gemcitabine-induced production of Bcl-2 and increased the expression of pro-apoptotic protein Bcl-2 interacting protein (BIM). Mouse xenograft experiments also confirmed the synergistic effect of gemcitabine and ABT-199 on tumor growth inhibition and the induction of tumor cell apoptosis.

CONCLUSION

Our results indicated that ABT-199 improved the anti-tumor effect of gemcitabine on pancreatic cancer by downregulating gemcitabine-induced overexpression of Bcl-2. ABT-199 has already been investigated in phase 3 clinical trials for chronic lymphocytic leukemia; therefore, it may serve as a potential drug to improve the sensitivity of pancreatic cancer to gemcitabine.

Hippo pathway mediates resistance to cytotoxic drugs

Chemotherapy is widely used for cancer treatment, but its effectiveness is limited by drug resistance. Here, we report a mechanism by which cell density activates the Hippo pathway, which in turn inactivates YAP, leading to changes in the regulation of genes that control the intracellular concentrations of gemcitabine and several other US Food and Drug Administration (FDA)-approved oncology drugs. Hippo inactivation sensitizes a diverse panel of cell lines and human tumors to gemcitabine in 3D spheroid, mouse xenografts, and patient-derived xenograft models. Nuclear YAP enhances gemcitabine effectiveness by down-regulating multidrug transporters as well by converting gemcitabine to a less active form, both leading to its increased intracellular availability. Cancer cell lines carrying genetic aberrations that impair the Hippo signaling pathway showed heightened sensitivity to gemcitabine. These findings suggest that "switching off" of the Hippo-YAP pathway could help to prevent or reverse resistance to some cancer therapies.

Molecular alterations contributing to pancreatic cancer chemoresistance

Pancreatic ductal adenocarcinoma (PDAC) is one of the most common causes of cancer-related death all over the world. This disease is difficult to treat and patients have an overall 5-year survival rate of less than 5%. Although two drugs, gemcitabine (GEM) and 5-fluorouracil (5-FU) have been shown to improve the survival rate of patients systematically, they do not increase general survival to a clinically acceptable degree. Lack of ideal clinical response of pancreatic cancer patients to chemotherapy is likely to be due to intrinsic and acquired chemoresistance of tumor cells. Various mechanisms of drug resistance have been investigated in pancreatic cancer, including genetic and epigenetic changes in particular genes or signaling pathways. In addition, evidence suggests that microRNAs (miRNAs) play significant roles as key regulators of gene expression in many cellular processes, including drug resistance. Understanding underlying genes and mechanisms of drug resistance in pancreatic cancer is critical to develop new effective treatments for this deadly disease. This review illustrates the genes and miRNAs involved in resistance to gemcitabine in pancreatic cancer.

Gemcitabine enhances rituximab-mediated complement-dependent cytotoxicity to B cell lymphoma by CD20 upregulation

Although rituximab, a chimeric monoclonal antibody that specifically binds to CD20, has significantly improved the prognosis for diffuse large B cell lymphoma (DLBCL), one-third of DLBCL patients demonstrate resistance to rituximab or relapse after rituximab treatment. Thus, a novel approach to rituximab-based treatment is likely to be required to improve the efficacy of DLBCL treatment. As complement dependent cytotoxicity (CDC) is a key mechanism mediating rituximab's tumoricidal activity, rituximab binding to CD20 on tumor cells is a critical factor for effective rituximab-based treatments against DLBCL. We found that gemcitabine (GEM), but not lenalidomide (LEN) or azacitidine (AZA), can upregulate CD20 expression in TK and KML-1 cells, two human DLBCL cell lines. Treatment of TK and KML-1 cells with GEM enhanced CD20 expression at both the mRNA and protein levels. CD20 upregulation by GEM treatment was accompanied by increased rituximab binding to CD20. In TK cells, GEM treatment synergistically increased rituximab-mediated CDC activity in a dose-dependent manner. In KML cells, GEM treatment also induced upregulation of complement regulatory proteins, possibly leading to resistance to CDC. Treatment with LEN, a drug that did not upregulate CD20, did not enhance rituximab-mediated CDC activity. GEM treatment activated nuclear factor-kappa B (NF-kB) signaling in these cells. Furthermore, a specific inhibitor to NF-kB suppressed GEM-induced CD20 upregulation, indicating that GEM-induced NF-kB activation is closely associated with CD20 upregulation. These results suggest that when used in combination, GEM might enhance the antitumor efficacy of rituximab against DLBCL due to its unique ability to upregulate CD20.

Silencing pancreatic adenocarcinoma upregulated factor (PAUF) increases the sensitivity of pancreatic cancer cells to gemcitabine

Pancreatic adenocarcinoma upregulated factor (PAUF) is a new oncogene that activates signaling pathways that play a critical role in resistance to gemcitabine. We thus speculated that PAUF also plays a role in resistance to gemcitabine of pancreatic cancer cells. We established BxPC-3 cell lines with stable PAUF knockdown (BxPC-3_shPAUF) and controls (BxPC-3_shCtrl) and evaluated sensitivity to gemcitabine in vitro by MTT and flow cytometry. We established a xenograft model of human pancreatic cancer to examine PAUF function in gemcitabine resistance in vivo. Gene chip microarrays were performed to identify differentially expressed genes in BxPC-3_shPAUF and BxPC-3_shCtrl cells. Silencing PAUF increased the sensitivity of BxPC-3 cells to gemcitabine in vitro and in vivo. PAUF-knockdown BxPC-3 cell lines treated with gemcitabine showed increased proliferation inhibition and apoptosis compared with controls. Gemcitabine exhibited a more pronounced effect on reduction of BxPC-3_shPAUF tumors than BxPC-3_shCtrl tumors. Terminal deoxynucleotidyl transferase dUTP Nick-End Labeling (TUNEL) assays confirmed a significantly higher apoptotic rate of BXPC-3_shPAUF tumors compared with BXPC-3_shCtrl tumors. Gene array showed that PAUF function in gemcitabine sensitivity might involve MRP2, MRP3, MDR1, PIK3R1, and NFkB2 genes. PAUF could be considered as a key molecular target for sensitizing pancreatic cancer cells to gemcitabine.

Pharmacodynamic modeling of combined chemotherapeutic effects predicts synergistic activity of gemcitabine and trabectedin in pancreatic cancer cells

PURPOSE

This study investigates the combined effects of gemcitabine and trabectedin (ecteinascidin 743) in two pancreatic cancer cell lines and proposes a pharmacodynamic (PD) model to quantify their pharmacological interactions.

METHODS

Effects of gemcitabine and trabectedin upon the pancreatic cancer cell lines MiaPaCa-2 and BxPC-3 were investigated using cell proliferation assays. Cells were exposed to a range of concentrations of the two drugs, alone and in combination. Viable cell numbers were obtained daily over 5 days. A model incorporating nonlinear cytotoxicity, transit compartments, and an interaction parameter ψ was used to quantify the effects of the individual drugs and combinations.

RESULTS

Simultaneous fitting of temporal cell growth profiles for all drug concentrations provided reasonable cytotoxicity parameter estimates (the cell killing rate constant K max and the sensitivity constant KC50) for each drug. The interaction parameter ψ was estimated as 0.806 for MiaPaCa-2 and 0.843 for BxPC-3 cells, suggesting that the two drugs exert modestly synergistic effects.

CONCLUSIONS

The proposed PD model enables quantification of the temporal profiles of drug combinations over a range of concentrations with drug-specific parameters. Based upon these in vitro studies, trabectedin may have augmented benefit in combination with gemcitabine. The PD model may have general relevance for the study of other cytotoxic drug combinations.

Histone deacetylase inhibitor trichostatin A resensitizes gemcitabine resistant urothelial carcinoma cells via suppression of TG-interacting factor

Gemcitabine and cisplatin (GC) has been widely used for advanced and metastatic urothelial carcinoma (UC). However, resistance to this remedy has been noticed. We have demonstrated that increase of TG-interacting factor (TGIF) in specimens is associated with worse prognosis of upper tract UC (UTUC) patients. The roles of TGIF in the gemcitabine resistance of UC were explored. Specimens of 23 locally advanced/advanced stage UTUC patients who received GC systemic chemotherapy after radical nephroureterectomy were collected to evaluate the alterations of TGIF in the resistance to the remedy by using immunohistochemistry. In vitro characterizations of mechanisms mediating TGIF in gemcitabine resistance were conducted by analyzing NTUB1 cells and their gemcitabine-resistant subline, NGR cells. Our results show that increased TGIF is significantly associated with chemo-resistance, poor progression-free survival, and higher cancer-related deaths of UTUC patients. Higher increases of TGIF, p-AKT(Ser473) and invasive ability were demonstrated in NGR cells. Overexpression of TGIF in NTUB1 cells upregulated p-AKT(Ser473) activation, enhanced migration ability, and attenuated cellular sensitivity to gemcitabine. Knockdown of TGIF in NGR cells downregulated p-AKT(Ser473) activation, declined migration ability, and enhanced cellular sensitivity to gemcitabine. In addition, histone deacetylases inhibitor trichostatin A (TSA) inhibited TGIF, p-AKT(Ser473) expression and migration ability. Synergistic effects of gemcitabine and TSA on NGR cells were also demonstrated. Collectively, TGIF contributes to the gemcitabine resistance of UC via AKT activation. Combined treatment with gemcitabine and TSA might be a promising therapeutic remedy to improve the gemcitabine resistance of UC.

The kinase inhibitor D11 induces caspase-mediated cell death in cancer cells resistant to chemotherapeutic treatment

Background

Multi-drug resistance and predisposition to metastasize are major clinical problems in cancer treatment. Malignant primary brain tumor and pancreatic cancer are two well-known examples of malignant tumors resistant to conventional therapies where aberrant EGFR-mediated and NF-κB signal transduction pathways are likely to play an important role. We have recently identified 1,3-Dichloro-6-[(E)-((4-methoxyphenyl)imino)methyl] diben-zo(b,d) furan-2,7-diol (D11) as a potent and selective inhibitor of CK2 a serine/threonine protein kinase that modulates the aforementioned signaling cascades.

Methods

Human cancer cell lines (glioblastoma and pancreatic adenocarcinoma) resistant to conventional chemotherapeutic agents were incubated with increasing concentrations of D11 for variable amounts of time. Cell viability, cell death and effects on major signal transduction pathways deregulated in cancer cells were analyzed by ELISA, FACS and Western blot-based assays, respectively. Moreover, effects on cell migration and in cell protein-protein association were investigated by wound-healing and in situ proximity ligation assays, respectively.

Results

We show here, that D11 treatment leads to i) significant caspase-mediated apoptotic cell death, ii) down-regulation of EGFR expression and iii) inhibition of NF-κB transcriptional activity. Furthermore, cell exposure to D11 results in impaired cell migration and correlates with reduced expression of the ion co-transporter and cell volume regulator Na⁺-K⁺-2Cl⁻ (NKCC1).

Conclusions

Data reported here underline the therapeutic potential of D11 with respect to certain types of cancer that carry aberrant intracellular signaling cascades and/or exhibit sustained cell migration and suggest a new therapeutic strategy against chemotherapy resistance.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-015-0234-6) contains supplementary material, which is available to authorized users.

RLN2 Is a Positive Regulator of AKT-2-Induced Gene Expression Required for Osteosarcoma Cells Invasion and Chemoresistance

The aim of the study was to determine the effect of H2 relaxin (RLN2) on invasion, migration, and chemosensitivity to cisplatin in human osteosarcoma U2-OS and MG-63 cells and then to investigate the effect of RLN2 on the AKT/NF-κB signaling pathway. The expression of RLN2, p-AKT (Ser473), and p-ERK1/2 (Phospho-Thr202/Tyr204) proteins was detected by western blot in OS tissues from 21 patients with pulmonary metastatic disease, and the correlation between RLN2 and p-AKT or RLN2 and p-ERK1/2 expression was investigated. RLN2 expression was inhibited by RLN2 siRNA transfection in the MG-63 cells. RLN2 was overexpressed in the U2-OS cells by treatment with recombinant relaxin. The results showed that positive relation was found between RLN2 and p-AKT expression in tissues of OS. Silencing RLN2 inhibited cell migratory and invasive ability and angiogenesis formation and increased the chemosensitivity to cisplatin in MG-63 cells. RLN2 overexpression promoted migratory and invasive ability and angiogenesis and increased the chemoresistance to cisplatin in U2-OS cells. Silencing RLN2 inhibited the activity of AKT/NF-κB signaling pathway in MG-63 cells, and vice versa. Blockage of both pathways by specific inhibitors abrogated RLN2-induced survival and invasion of OS cells, and vice versa. Our results indicated RLN2 confers to migratory and invasive ability, angiogenesis, and chemoresistance to cisplatin via modulating the AKT/NF-κB signaling pathway in vitro.

Altering cancer transcriptomes using epigenomic inhibitors

Background

Due to the hyper-activation of WNT signaling in a variety of cancer types, there has been a strong drive to develop pathway-specific inhibitors with the eventual goal of providing a chemotherapeutic antagonist of WNT signaling to cancer patients. A new category of drugs, called epigenetic inhibitors, are being developed that hold high promise for inhibition of the WNT pathway. The canonical WNT signaling pathway initiates when WNT ligands bind to receptors, causing the nuclear localization of the co-activator β-catenin (CTNNB1), which leads to an association of β-catenin with a member of the TCF transcription factor family at regulatory regions of WNT-responsive genes. The TCF/β-catenin complex then recruits CBP (CREBBP) or p300 (EP300), leading to histone acetylation and gene activation. A current model in the field is that CBP-driven expression of WNT target genes supports proliferation whereas p300-driven expression of WNT target genes supports differentiation. The small molecule inhibitor ICG-001 binds to CBP, but not to p300, and competitively inhibits the interaction of CBP with β-catenin. Upon treatment of cancer cells, this should reduce expression of CBP-regulated transcription, leading to reduced tumorigenicity and enhanced differentiation.

Results

We have compared the genome-wide effects on the transcriptome after treatment with ICG-001 (the specific CBP inhibitor) versus C646, a compound that competes with acetyl-coA for the Lys-coA binding pocket of both CBP and p300. We found that both drugs cause large-scale changes in the transcriptome of HCT116 colon cancer cells and PANC1 pancreatic cancer cells and reverse some tumor-specific changes in gene expression. Interestingly, although the epigenetic inhibitors affect cell cycle pathways in both the colon and pancreatic cancer cell lines, the WNT signaling pathway was affected only in the colon cancer cells. Notably, WNT target genes were similarly downregulated after treatment of HCT116 with C646 as with ICG-001.

Conclusion

Our results suggest that treatment with a general HAT inhibitor causes similar effects on the transcriptome as does treatment with a CBP-specific inhibitor and that epigenetic inhibition affects the WNT pathway in HCT116 cells and the cholesterol biosynthesis pathway in PANC1 cells.

Electronic supplementary material

The online version of this article (doi:10.1186/1756-8935-8-9) contains supplementary material, which is available to authorized users.

Ratio of phosphorylated HSP27 to nonphosphorylated HSP27 biphasically acts as a determinant of cellular fate in gemcitabine-resistant pancreatic cancer cells

Gemcitabine has been used most commonly as an anticancer drug to treat advanced pancreatic cancer patients. However, intrinsic or acquired resistance of pancreatic cancer to gemcitabine was also developed, which leads to very low five-year survival rates. Here, we investigated whether cellular levels of HSP27 phosphorylation act as a determinant of cellular fate with gemcitabine. In addition we have demonstrated whether HSP27 downregulation effectively could overcome the acquisition of gemcitabine resistance by using transcriptomic analysis. We observed that gemcitabine induced p38/HSP27 phosphorylation and caused acquired resistance. After acquisition of gemcitabine resistance, cancer cells showed higher activity of NF-κB. NF-κB activity, as well as colony formation in gemcitabine-resistant pancreatic cancer cells, was significantly decreased by HSP27 downregulation and subsequent TRAIL treatment, showing that HSP27 was a common network mediator of gemcitabine/TRAIL-induced cell death. After transcriptomic analysis, gene fluctuation after HSP27 downregulation was very similar to that of pancreatic cancer cells susceptible to gemcitabine, and then in opposite position to that of acquired gemcitabine resistance, which makes it possible to downregulate HSP27 to overcome the acquired gemcitabine resistance to function as an overall survival network inhibitor. Most importantly, we demonstrated that the ratio of phosphorylated HSP27 to nonphosphorylated HSP27 rather than the cellular level of HSP27 itself acts biphasically as a determinant of cellular fate in gemcitabine-resistant pancreatic cancer cells.

Identification of genomic alterations in pancreatic cancer using array-based comparative genomic hybridization

Background

Genomic aberration is a common feature of human cancers and also is one of the basic mechanisms that lead to overexpression of oncogenes and underexpression of tumor suppressor genes. Our study aims to identify frequent genomic changes in pancreatic cancer.

Materials and Methods

We used array comparative genomic hybridization (array CGH) to identify recurrent genomic alterations and validated the protein expression of selected genes by immunohistochemistry.

Results

Sixteen gains and thirty-two losses occurred in more than 30% and 60% of the tumors, respectively. High-level amplifications at 7q21.3–q22.1 and 19q13.2 and homozygous deletions at 1p33–p32.3, 1p22.1, 1q22, 3q27.2, 6p22.3, 6p21.31, 12q13.2, 17p13.2, 17q21.31 and 22q13.1 were identified. Especially, amplification of AKT2 was detected in two carcinomas and homozygous deletion of CDKN2C in other two cases. In 15 independent validation samples, we found that AKT2 (19q13.2) and MCM7 (7q22.1) were amplified in 6 and 9 cases, and CAMTA2 (17p13.2) and PFN1 (17p13.2) were homozygously deleted in 3 and 1 cases. AKT2 and MCM7 were overexpressed, and CAMTA2 and PFN1 were underexpressed in pancreatic cancer tissues than in morphologically normal operative margin tissues. Both GISTIC and Genomic Workbench software identified 22q13.1 containing APOBEC3A and APOBEC3B as the only homozygous deletion region. And the expression levels of APOBEC3A and APOBEC3B were significantly lower in tumor tissues than in morphologically normal operative margin tissues. Further validation showed that overexpression of PSCA was significantly associated with lymph node metastasis, and overexpression of HMGA2 was significantly associated with invasive depth of pancreatic cancer.

Conclusion

These recurrent genomic changes may be useful for revealing the mechanism of pancreatic carcinogenesis and providing candidate biomarkers.

Insulin-like growth factor 1 receptor (IGF-1R) as a target of MiR-497 and plasma IGF-1R levels associated with TNM stage of pancreatic cancer

The expression levels and regulatory roles of miR-497 in pancreatic cancer are unclear. The clinical value of plasma insulin-like growth factor 1 receptor (IGF-1R) in pancreatic cancers has not been investigated. In the present study, we demonstrated that miR-497 was significantly downregulated in pancreatic cancer tissues. Upregulation of miR-497 in BxPC-3 and AsPC-1 pancreatic cancer cell lines inhibited proliferation, enhanced apoptosis, re-sensitized cells to gemcitabine and suppressed IGF-1R and p-AKT expression through direct downregulation of IGF-1R protein expression. Opposite effects were observed after downregulation of miR-497. Plasma IGF-1R levels in patients with pancreatic cancer increased significantly, compared with that in patients with chronic pancreatitis, other pancreatic tumors and pancreatic neuroendocrine tumors (P = 0.006, P = 0.018 and P = 0.004, respectively), and displayed potential values for distinguishing pancreatic lesions. However, the levels in pancreatic cancer patients were comparable to that in healthy volunteers (P = 0.095). The tumor locations and TNM stage were associated with plasma IGF-1R levels (P = 0.013 and P = 0.01, respectively). There was no significant difference of overall survival between high and low IGF-1R expression groups. In conclusion, we demonstrated that miR-497 attenuated the malignancy of pancreatic cancer cells and promoted sensitivity of cells to gemcitabine by directly downregulation of IGF-1R expression. Plasma IGF-1R displayed a potential value for distinguishing pancreatic lesions and could be a new biomarker for guiding TNM stage of pancreatic cancer.

An innovative hydrogel of gemcitabine-loaded lipid nanocapsules: when the drug is a key player of the nanomedicine structure

A new method to form a nanoparticle-structured hydrogel is reported; it is based on the drug being loaded into the nanoparticles to form a solid structure. A lipophilic form of gemcitabine (modified lauroyl), an anti-cancer drug, was encapsulated in lipid nanocapsules (LNCs), using a phase-inversion temperature process. A gel was formed spontaneously, depending on the LNC concentration. The drug loading, measured with total entrapment efficiency, and the rheological properties of the gel were assessed. Physical studies (surface tension measurements) showed that modified gemcitabine was localised at the oil-water interface of the LNC, and that the gemcitabine moieties of the prodrug were exposed to the water phase. This particular assembly promoted inter-LNC interactions via hydrogen bonds between gemcitabine moieties that led to an LNC gel structure in water, without a matrix, like a tridimensional pearl necklace. Dilution of the gel produced a gemcitabine-loaded LNC suspension in water, and these nanoparticles presented cytotoxic activity to various cancer cell lines to a greater degree than the native drug. Finally, the syringeability of the formulation was successfully tested and perspectives of its use as a nanomedicine (intratumoural or subcutaneous injection) can be foreseen.

Activation of ERK1/2 and Akt is associated with cisplatin resistance in human lung cancer cells

Cisplatin is widely used for the treatment of solid tumours including small cell lung cancers, but its success is often compromised by relapse and resistance to further treatment. Extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt are two major cell survival pathways that are upregulated and activated in lung cancer tissues. Phosphorylated ERK1/2 (p-ERK1/2) and Akt (p-Akt) can be further stimulated by chemotherapeutics in cancer cells. Although individually targeting the ERK1/2 or Akt pathway has been reported to sensitize cancer cells to therapy, the effect of concurrently blocking these two pathways on the sensitivity of lung cancer cells to cisplatin has not been investigated. In the present study, we aimed to determine whether the ERK1/2 and Akt pathways contribute to cisplatin resistance in human small cell lung cancer A549 cells. The results showed that cisplatin activates p-ERK1/2 and p-Akt in A549 cells. Blockade of either of these pathways with chemical inhibitors moderately sensitized A549 cells to cisplatin-induced apoptosis and reduced cell viability. Strikingly, concurrent inhibition of p-ERK1/2 and p-Akt significantly potentiated cisplatin cytotoxicity in vitro and in vivo. The sensitization of A549 cells to cisplatin cytotoxicity induced by p-Akt inhibition was mediated by the upregulation of PUMA, whereas that induced by p-ERK1/2 inhibition occurred by Bcl-2 downregulation. These data indicate that the cooperative effects of p-ERK1/2 and p-Akt on attenuating cisplatin cytotoxicity are mediated by PUMA and Bcl-2 regulation, and concurrently blocking these pathways may be an effective strategy for improving the efficacy of cisplatin as anticancer treatment.

Insulin-like growth factor 1 receptor promotes the growth and chemoresistance of pancreatic cancer

BACKGROUND

Insulin-like growth factor 1 receptor (IGF1R) plays important roles in the progression of pancreatic cancer. However, the underlying mechanism remains unclear.

AIMS

The purpose of this study was to investigate the effects of IGF1R knockdown on the proliferation, apoptosis and chemosensitivity of pancreatic cancer cells, and explore the possible mechanisms.

METHODS

Pancreatic cancer cells expressing IGF1R shRNA were established, and the cell proliferation, colony formation, and chemosensitivity to gemcitabine were examined in vitro. The activation of AKT and NF-κB was detected by Western blot analysis and luciferase assay, respectively. Xenograft mice models were established to evaluate the in vivo anti-tumor effects of IGF1R knockdown.

RESULTS

IGF1R knockdown notably inhibited pancreatic cancer cell proliferation and colony formation, induced apoptosis, and inhibited xenograft tumor growth. Moreover, IGF1R knockdown significantly enhanced chemosensitivity to gemcitabine in pancreatic cancer cells, and this was correlated with the inhibition of PI3K/AKT and NF-κB pathways.

CONCLUSIONS

IGF1R knockdown suppresses tumor growth and enhances chemosensitivity in pancreatic cancer via the inhibition of PI3K/AKT and NF-κB pathways, and is a promising approach to overcome the chemoresistance of pancreatic cancer.

Involvement of Akt2/protein kinase B β (PKBβ) in the 8-Cl-cAMP-induced cancer cell growth inhibition

8-chloro-cyclic AMP (8-Cl-cAMP), which induces differentiation, growth inhibition, and apoptosis in various cancer cells, has been investigated as a putative anti-cancer drug. However, the exact mechanism of 8-Cl-cAMP functioning in cancer cells is not fully understood. Akt/protein kinase B (PKB) genes (Akt1, Akt2, and Akt3) encode enzymes belonging to the serine/threonine-specific protein kinase family. It has been suggested that Akt/PKB enhances cell survival by inhibiting apoptosis. Recently, we showed that 8-Cl-cAMP and 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) inhibited cancer cell growth through the activation of AMPK and p38 MAPK. Therefore, we anticipated that the phosphorylation of Akt/PKB would be decreased upon treatment with 8-Cl-cAMP. However, treatment with 8-Cl-cAMP and AICAR induced the phosphorylation of Akt/PKB, which was inhibited by ABT702 (an adenosine kinase inhibitor) and NBTI (an adenosine transporter inhibitor). Furthermore, whereas Compound C (an AMPK inhibitor), AMPK-DN (AMPK-dominant negative) mutant, and SB203580 (a p38 MAPK inhibitor) did not block the 8-Cl-cAMP-induced phosphorylation of Akt/PKB, TCN (an Akt1/2/3 specific inhibitor) and an Akt2/PKBβ-targeted siRNA inhibited the 8-Cl-cAMP- and AICAR-mediated phosphorylation of AMPK and p38 MAPK. TCN also reversed the growth inhibition mediated by 8-Cl-cAMP and AICAR. Moreover, an Akt1/PKBα-targeted siRNA did not reduce the phosphorylation of AMPK and p38 MAPK after treatment with 8-Cl-cAMP. These results suggest that Akt2/PKBβ activation promotes the phosphorylation of AMPK and p38 MAPK during the 8-Cl-cAMP- and AICAR-induced growth inhibition.

Genome-wide characterization of pancreatic adenocarcinoma patients using next generation sequencing

Pancreatic adenocarcinoma (PAC) is among the most lethal malignancies. While research has implicated multiple genes in disease pathogenesis, identification of therapeutic leads has been difficult and the majority of currently available therapies provide only marginal benefit. To address this issue, our goal was to genomically characterize individual PAC patients to understand the range of aberrations that are occurring in each tumor. Because our understanding of PAC tumorigenesis is limited, evaluation of separate cases may reveal aberrations, that are less common but may provide relevant information on the disease, or that may represent viable therapeutic targets for the patient. We used next generation sequencing to assess global somatic events across 3 PAC patients to characterize each patient and to identify potential targets. This study is the first to report whole genome sequencing (WGS) findings in paired tumor/normal samples collected from 3 separate PAC patients. We generated on average 132 billion mappable bases across all patients using WGS, and identified 142 somatic coding events including point mutations, insertion/deletions, and chromosomal copy number variants. We did not identify any significant somatic translocation events. We also performed RNA sequencing on 2 of these patients' tumors for which tumor RNA was available to evaluate expression changes that may be associated with somatic events, and generated over 100 million mapped reads for each patient. We further performed pathway analysis of all sequencing data to identify processes that may be the most heavily impacted from somatic and expression alterations. As expected, the KRAS signaling pathway was the most heavily impacted pathway (P<0.05), along with tumor-stroma interactions and tumor suppressive pathways. While sequencing of more patients is needed, the high resolution genomic and transcriptomic information we have acquired here provides valuable information on the molecular composition of PAC and helps to establish a foundation for improved therapeutic selection.

Genome-wide characterization of pancreatic adenocarcinoma patients using next generation sequencing

Pancreatic adenocarcinoma (PAC) is among the most lethal malignancies. While research has implicated multiple genes in disease pathogenesis, identification of therapeutic leads has been difficult and the majority of currently available therapies provide only marginal benefit. To address this issue, our goal was to genomically characterize individual PAC patients to understand the range of aberrations that are occurring in each tumor. Because our understanding of PAC tumorigenesis is limited, evaluation of separate cases may reveal aberrations, that are less common but may provide relevant information on the disease, or that may represent viable therapeutic targets for the patient. We used next generation sequencing to assess global somatic events across 3 PAC patients to characterize each patient and to identify potential targets. This study is the first to report whole genome sequencing (WGS) findings in paired tumor/normal samples collected from 3 separate PAC patients. We generated on average 132 billion mappable bases across all patients using WGS, and identified 142 somatic coding events including point mutations, insertion/deletions, and chromosomal copy number variants. We did not identify any significant somatic translocation events. We also performed RNA sequencing on 2 of these patients' tumors for which tumor RNA was available to evaluate expression changes that may be associated with somatic events, and generated over 100 million mapped reads for each patient. We further performed pathway analysis of all sequencing data to identify processes that may be the most heavily impacted from somatic and expression alterations. As expected, the KRAS signaling pathway was the most heavily impacted pathway (P<0.05), along with tumor-stroma interactions and tumor suppressive pathways. While sequencing of more patients is needed, the high resolution genomic and transcriptomic information we have acquired here provides valuable information on the molecular composition of PAC and helps to establish a foundation for improved therapeutic selection.