A review of kinases implicated in pancreatic cancer

PDGFRβ targeted innovative imaging probe for pancreatic adenocarcinoma detection

The 5-year survival rate for pancreatic adenocarcinoma (PA) is less than 10%, making it one of the most lethal forms of cancer. Early-stage diagnosis and resection of the incipient lesions could increase the 4-year survival rate of PA up to 78%. Platelet-derived growth factor receptor β (PDGFRβ), an oncogenic key regulator for migration, proliferation and angiogenesis of cancer cells, has been proved to be aberrantly expressed in the majority of PA. Herein, by amino acid substitution strategy and surface plasmon resonance (SPR) analysis, we designed a novel PDGFRβ-targeting peptide (YQGX-10) with high affinity (K_d = 227.7 nM) and coupled it with a near-infrared fluorescent (NIRF) dye MPA for precisely detection of PA. Great binding affinity and specificity were displayed in a series of in vitro assays. NIRF imaging experiments demonstrated that the synthesized probe could be highly accumulated in xenograft and orthotopic BxPC-3 tumors and provide favorable tumor contrast in the mice, offering a potential novel approach for the early diagnosis of PA. Moreover, YQGX-10 could visualize tumor boundaries and minor lesions in BxPC-3 xenograft mice, shedding a new light on NIRF-guided tumor resection of PA. In addition, we successfully constructed the radioactive probe ^99mTc-HYNIC-YQGX-10 for the diagnosis of PA with high specificity and sensitivity. In summary, the probe warrants further exploration for clinical translation in the early diagnosis and NIRF-guided surgery of PA.

Impact of posttranslational modifications in pancreatic carcinogenesis and treatments

Pancreatic cancer (PC) is a highly aggressive cancer, with a 9% 5-year survival rate and a high risk of recurrence. In part, this is because PC is composed of heterogeneous subgroups with different biological and functional characteristics and personalized anticancer treatments are required. Posttranslational modifications (PTMs) play an important role in modifying protein functions/roles and are required for the maintenance of cell viability and biological processes; thus, their dysregulation can lead to disease. Different types of PTMs increase the functional diversity of the proteome, which subsequently influences most aspects of normal cell biology or pathogenesis. This review primarily focuses on ubiquitination, SUMOylation, and NEDDylation, as well as the current understanding of their roles and molecular mechanisms in pancreatic carcinogenesis. Additionally, we briefly summarize studies and clinical trials on PC treatments to advance our knowledge of drugs available to target the ubiquitination, SUMOylation, and NEDDylation PTM types. Further investigation of PTMs could be a critical field of study in relation to PC, as they have been implicated in the initiation and progression of many other types of cancer.

Inhibitory Mechanisms of Lusianthridin on Human Platelet Aggregation

Lusianthridin is a phenanthrene derivative isolated from Dendrobium venustum. Some phenanthrene compounds have antiplatelet aggregation activities via undefined pathways. This study aims to determine the inhibitory effects and potential mechanisms of lusianthridin on platelet aggregation. The results indicated that lusianthridin inhibited arachidonic acid, collagen, and adenosine diphosphate (ADP)-stimulated platelet aggregation (IC₅₀ of 0.02 ± 0.001 mM, 0.14 ± 0.018 mM, and 0.22 ± 0.046 mM, respectively). Lusianthridin also increased the delaying time of arachidonic acid-stimulated and the lag time of collagen-stimulated and showed a more selective effect on the secondary wave of ADP-stimulated aggregations. Molecular docking studies revealed that lusianthridin bound to the entrance site of the cyclooxygenase-1 (COX-1) enzyme and probably the active region of the cyclooxygenase-2 (COX-2) enzyme. In addition, lusianthridin showed inhibitory effects on both COX-1 and COX-2 enzymatic activities (IC₅₀ value of 10.81 ± 1.12 µM and 0.17 ± 1.62 µM, respectively). Furthermore, lusianthridin significantly inhibited ADP-induced suppression of cAMP formation in platelets at 0.4 mM concentration (p < 0.05). These findings suggested that possible mechanisms of lusianthridin on the antiplatelet effects might act via arachidonic acid-thromboxane and adenylate cyclase pathways.

Inhibiting p21-activated kinase (PAK7) enhances radiosensitivity in hepatocellular carcinoma

OBJECTIVE

In light of the upregulation of p21-activated kinase (PAK7) in a variety of cancers, including hepatocellular carcinoma (HCC), we aimed to investigate the effect of PAK7 on the sensitivity of HCC cells to radiotherapy.

METHODS

PAK7 expression was determined in normal adult liver epithelial THLE-2 and human HCC cell lines. The effect of ionizing radiation (IR) on the HCC cell viability was evaluated by Sulforhodamine B (SRB) assay. HCC cell lines Mahlavu and Huh7 were chosen to assess the effect of PAK7 shRNAs on the viability, clone formation, apoptosis, cycle distribution and γ-H2AX expression after exposure to IR.

RESULTS

As compared to THLE-2 cells, PAK7 was upregulated in poorly differentiated Mahlavu and SK-Hep-1 cells, but moderately or lowly expressed in well-differentiated Huh7 and HepG2 cells. HCC cells with moderate or low expression of PAK7 presented a decreased viability at 2 Gy IR, which had no significant effect on PAK7_high HCC cells. Mahlavu and Huh7 cells transfected with PAK7 shRNAs showed increased inhibitory effect of IR on viability. In addition, PAK7 shRNAs reduced clone formation, facilitated the cell apoptosis, arrested cells at G2/M phase, and increased γ-H2AX expression. Moreover, changes above were more evident in the HCC cells co-treated with IR and PAK7 shRNAs.

CONCLUSION

PAK7 downregulation could inhibit the viability, promote the apoptosis, arrest cells in G2/M phase, and induce the DNA damage in HCC cells, thereby enhancing the radiosensitivity in HCC.

Invadopodia: A potential target for pancreatic cancer therapy

Dissemination of cancer cells is an intricate multistep process that represents the most deadly aspect of cancer. Cancer cells form F-actin-rich protrusions known as invadopodia to invade surrounding tissues, blood vessels and lymphatics. A number of studies have demonstrated the significant roles of invadopodia in cancer. Therefore, the specific cells and molecules involved in invadopodia activity can provide as therapeutic targets. In this review, we included a thorough overview of studies in invadopodia and discussed their functions in cancer metastasis. We then presented the specific cells and molecules involved in invadopodia activity in pancreatic cancer and analyzed their suitability to be effective therapeutic targets. Currently, drugs targeting invadopodia and relevant clinical trials are negligible. Here, we highlighted the significance of potential drugs and discussed future obstacles in implementing clinical trials. This review presents a new perspective on invadopodia-induced pancreatic cancer metastasis and may prosper the development of targeted therapeutics against pancreatic cancer.

PAK5 promotes the cell stemness ability by phosphorylating SOX2 in lung squamous cell carcinomas

Growing evidences suggest that the overexpression of p21-activated kinase 5 (PAK5) plays an important role in various tumor progression. However, the role of PAK5 and its downstream target gene(s) in lung squamous cell carcinomas (LUSC) are waiting to be elucidated. TCGA data were utilized to evaluate the expression levels of PAK5 in LUSC. We then explored the role of PAK5 in maintaining the stem-like phenotype of lung squamous cancer cells through RT-PCR, flow cytometry, oncosphere-forming assay. In addition, co-immunoprecipitation, western blotting and immunofluorescence assays were used to determine SOX2 as a novel effector of PAK5. Xenograft models in nude mice were established to explore the roles of PAK5 in lung cancer growth. In this study, we have shown that PAK5 is overexpressed in LUSC tissues. The absence of PAK5 abolishes self-renewal ability of LUSC cells by decreasing the expression and phosphorylation of SOX2 in vitro and in vivo. In xenograft models, knockdown or pharmacological inhibition of PAK5 suppressed the tumor growth and metastasis of lung squamous cancer cells in vivo. Taken together, our findings suggest that the PAK5-mediated SOX2 phosphorylation promoted the cancer stem cell-like phenotype of LUSC cells. PAK5 inhibition may be a promising target in the treatment of SOX2 positive lung squamous cell cancer.

PAK5 facilitates the proliferation, invasion and migration in colorectal cancer cells

Colorectal cancer (CRC) is the third-most common cancer around the world, accounting for approximately 10% of cancer-related mortality. Deeper molecular understanding of colorectal carcinogenesis will provide evidences for identification of early diagnostic indicators and novel therapeutic strategies for CRC treatment. The p21cdc42/rac1 -activated kinase 5 (PAK5) has been reported to be involved in a variety of tumor-promoting behaviors, whereas the underlying mechanisms of PAK5 in CRC progression are still obscure. Our current study revealed an upregulated expression of PAK5 in human CRC tissues as compared with normal adjacent biopsies, which was associated with tumor progression and metastasis. We further unraveled that inhibition of PAK5 was correlated with restrained proliferation, migration, and invasion of CRC cells in vitro and in vivo. Moreover, we showed an indispensable role of PAK5 in interacting with Cdc42 and Integrin β1, β3, thus, to facilitate the migration and invasion of CRC cells. Collectively, we pointed out a potential of PAK5 to serve as a novel therapeutic target in restricting CRC proliferation and metastasis. The uncovered mechanisms will deepen the comprehension with regard to the mechanisms of CRC progression, as well as providing new insights for therapeutic intervention in colorectal cancer.

Host-Directed Antiviral Therapy

Antiviral drugs have traditionally been developed by directly targeting essential viral components. However, this strategy often fails due to the rapid generation of drug-resistant viruses. Recent genome-wide approaches, such as those employing small interfering RNA (siRNA) or clustered regularly interspaced short palindromic repeats (CRISPR) or those using small molecule chemical inhibitors targeting the cellular "kinome," have been used successfully to identify cellular factors that can support virus replication. Since some of these cellular factors are critical for virus replication, but are dispensable for the host, they can serve as novel targets for antiviral drug development. In addition, potentiation of immune responses, regulation of cytokine storms, and modulation of epigenetic changes upon virus infections are also feasible approaches to control infections. Because it is less likely that viruses will mutate to replace missing cellular functions, the chance of generating drug-resistant mutants with host-targeted inhibitor approaches is minimized. However, drug resistance against some host-directed agents can, in fact, occur under certain circumstances, such as long-term selection pressure of a host-directed antiviral agent that can allow the virus the opportunity to adapt to use an alternate host factor or to alter its affinity toward the target that confers resistance. This review describes novel approaches for antiviral drug development with a focus on host-directed therapies and the potential mechanisms that may account for the acquisition of antiviral drug resistance against host-directed agents.

Binding of ellagic acid and urolithin metabolites to the CK2 protein, based on the ONIOM method and molecular docking calculations

Using three-layer ONIOM and molecular docking calculations to investigate the binding of urolithins to the active site of the CK2 protein.

PAK5 overexpression is associated with lung metastasis in osteosarcoma

p21-activated kinases (PAKs) are multifunctional effectors of Rho GTPases, which are associated with cytoskeletal organization, cellular morphogenesis, migration and survival. PAKs are overactive in a number of tumor tissues and have attracted attention as a potential target for cancer therapy. In the present study, PAK5 levels were analyzed in primary osteosarcoma (OS) samples (n=65) using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and immunohistochemistry (IHC) methods. In the primary OS tissue, increased PAK5 expression (IHC score >2, n=37) was associated with significantly decreased overall survival (P=0.036) compared with decreased PAK5 expression (IHC score ≤2, n=28). PAK5 expression was identified to be significantly associated with metastasis (P=0.010). The lung is the most common metastasis site for OS. In addition, the level of PAK5 in lung metastasis tissue (n=13) was detected using RT-qPCR and IHC methods. PAK5 expression was increased in lung metastasis tissue compared with in primary OS samples. PAK5 was silenced using short hairpin RNA in OS cell lines. Wound healing, migration and nude mice model assay results consistently demonstrated that PAK5 knockdown was able to significantly inhibit OS migration. In PAK5-knockdown cells, the alteration in the expression of a number of metastasis-associated factors, including epithelial cadherin, vimentin, fibronectin and matrix metalloproteinase 2 (MMP2), was analyzed. Only MMP2 expression was decreased significantly (P<0.05). The expression level of MMP2 was analyzed in primary OS tissue and lung metastasis tissue using RT-qPCR and IHC methods. Expression of MMP2 was identified to be associated with expression of PAK5. The results of the present study suggest that PAK5 promotes OS cell migration and that PAK5 expression may be used to predict lung metastasis.

EGFR-induced phosphorylation of type Iγ phosphatidylinositol phosphate kinase promotes pancreatic cancer progression

Pancreatic cancer is one of the deadliest malignancies and effective treatment has always been lacking. In current study, we investigated how the type Iγ phosphatidylinositol phosphate kinase (PIPKIγ) participates in the progression of pancreatic ductal adenocarcinoma (PDAC) for novel therapeutic potentials against this lethal disease. We found that PIPKIγ is up-regulated in all tested PDAC cell lines. The growth factor (including EGFR)-induced tyrosine phosphorylation of PIPKIγ is significantly elevated in in situ and metastatic PDAC tissues. Loss of PIPKIγ inhibits the aggressiveness of PDAC cells by restraining the activities of AKT and STAT3, as well as MT1-MMP expression. Therefore when planted into the pancreas of nude mice, PIPKIγ-depleted PDAC cells exhibits substantially repressed tumor growth and metastasis comparing to control PDAC cells. Results from further studies showed that the phosphorylation-deficient PIPKIγ mutant, unlike its wild-type counterpart, cannot rescue PDAC progression inhibited by PIPKIγ depletion. These findings indicate that PIPKIγ, functioning downstream of EGFR signaling, is critical to the progression of PDAC, and suggest that PIPKIγ is potentially a valuable therapeutic target for PDAC treatment.

MicroRNA-526a targets p21-activated kinase 7 to inhibit tumorigenesis in hepatocellular carcinoma

MicroRNAs belong to a series of noncoding RNAs and have diverse roles in several biological processes. The association between aberrant microRNA expression and tumorigenesis is complex and remains to be fully elucidated. The present study investigated whether microRNA (miR) ‑526a can suppress the progression of hepatocellular carcinoma (HCC) in vitro and in vivo. Reverse transcription‑quantitative polymerase chain reaction, luciferase reporter assay, invasion assay, western blotting and in vivo implantation were used to investigate the potential function of miR‑526a. The present study observed that the level of miR‑526a was downregulated in HCC tissues and well‑established cell lines. In addition, the ectopic introduction of miR‑526a into Huh7 and HepG2 cells significantly attenuated HCC tumorigenesis, including proliferation, migration and invasion. The growth of tumor xenografts was also inhibited following transfection with miR‑526a. Using overlapping strategies, p21‑activated kinase 7 (PAK7) was predicted to be a target for miR‑526a, and this was verified experimentally. An inverse correlation was found between miR‑526a and PAK7 in HCC tissues. The results of the present study revealed a novel function of miR‑526a and may provide crucial insight into therapeutic interventions targeting microRNAs.

Autophagy Induced by CX-4945, a Casein Kinase 2 Inhibitor, Enhances Apoptosis in Pancreatic Cancer Cell Lines

OBJECTIVES

Pancreatic cancer is the most lethal malignancy with only a few effective chemotherapeutic drugs. Because the inhibition of casein kinase 2 (CK2) has been reported as a novel therapeutic strategy for many cancers, we investigated the effects of CK2 inhibitors in pancreatic cancer cell lines.

METHODS

The BxPC3, 8902, MIA PaCa-2 human pancreatic cancer cell lines, and CX-4945, a novel CK2 inhibitor, were used. Autophagy was analyzed by acridine orange staining, fluorescence microscope detection of punctuate patterns of GFP-tagged LC3 and immunoblotting for LC3. Cell survival, cell cycle, and apoptosis analysis was performed.

RESULTS

CX-4945 induced significant inhibition of proliferation and triggered autophagy in pancreatic cancer cells. This suppression of proliferation was caused by the direct inhibition of CK2α, which was required for autophagy and apoptosis in pancreatic cancer cells. CX-4945 suppressed cell cycle progression in G2/M and induced apoptosis. The inhibition of CX-4945-induced autophagy was rescued by 3-methyladenine or small interfering RNA against Atg7, which attenuated apoptosis in pancreatic cancer cells.

CONCLUSIONS

CX-4945, a potent and selective inhibitor of CK2, effectively induces autophagy and apoptosis in pancreatic cancer cells, indicating that the induction of autophagy by CX-4945 may have an important role in the treatment of pancreatic cancer.

Structure-activity relationship study of 4-(thiazol-5-yl)benzoic acid derivatives as potent protein kinase CK2 inhibitors

Two classes of modified analogs of 4-(thiazol-5-yl)benzoic acid-type CK2 inhibitors were designed. The azabenzene analogs, pyridine- and pyridazine-carboxylic acid derivatives, showed potent protein kinase CK2 inhibitory activities [IC50 (CK2α)=0.014-0.017μM; IC50 (CK2α')=0.0046-0.010μM]. Introduction of a 2-halo- or 2-methoxy-benzyloxy group at the 3-position of the benzoic acid moiety maintained the potent CK2 inhibitory activities [IC50 (CK2α)=0.014-0.016μM; IC50 (CK2α')=0.0088-0.014μM] and led to antiproliferative activities [CC50 (A549)=1.5-3.3μM] three to six times higher than those of the parent compound.

PAK5-mediated E47 phosphorylation promotes epithelial-mesenchymal transition and metastasis of colon cancer

The p21-activated kinase 5 (PAK5) is overexpressed in advanced cancer and the transcription factor E47 is a direct repressor of E-cadherin and inducer of epithelial-mesenchymal transition (EMT). However, the relationship between PAK5 and E47 has not been explored. In this study, we found that PAK5-mediated E47 phosphorylation promoted EMT in advanced colon cancer. PAK5 interacted with E47 and phosphorylated E47 on Ser39 under hepatocyte growth factor (HGF) stimulation, which decreased cell-cell cohesion, increased cell migration and invasion in vitro and promoted metastasis in a xenograft model. Furthermore, phosphorylation of E47 facilitated its accumulating in nucleus in an importin α-dependent manner, and enhanced E47 binding to E-cadherin promoter directly, leading to inhibition of E-cadherin transcription. In contrast, PAK5-knockdown resulted in blockage of HGF-induced E47 phosphorylation, attenuated association of E47 with importin α and decreased E47 binding to E-cadherin promoter. In addition, we demonstrated a close correlation between PAK5 and phospho-Ser39 E47 expression in colon cancer specimens. More importantly, high expression of phospho-E47 was associated with an aggressive phenotype of colon cancer and nuclear phospho-E47 staining was found in certain cases of colon cancer with metastasis. Collectively, E47 is a novel substrate of PAK5, and PAK5-mediated phosphorylation of E47 promotes EMT and metastasis of colon cancer, suggesting that phosphorylated E47 on Ser39 may be a potential therapeutic target in progressive colon cancer.

MicroRNA-100 regulates pancreatic cancer cells growth and sensitivity to chemotherapy through targeting FGFR3

We intended to investigate the role of microRNA 100 (miR-100) in regulating pancreatic cancer cells' growth in vitro and tumor development in vivo. QTR-PCR was used to examine the expression of miR-100 in pancreatic cancer cell lines and tumor cells from human patients. Lentivirual vector containing miR-100 mimics (lv-miR-100) was used to overexpress miR-100 in MIA PaCa-2 and FCPAC-1 cells. The effects of overexpressing miR-100 on pancreatic cancer cell proliferation and chemosensitivity to cisplatin were examined by cell proliferation essay in vitro. MIA PaCa-2 cells with endogenously overexpressed miR-100 were transplanted into null mice to examine tumor growth in vivo. The predicted target of miR-100, fibroblast growth factor receptor 3 (FGFR3), was downregulated by siRNA to examine its effect on pancreatic cancer cells. We found miR-100 was markedly underexpressed in both pancreatic cancer cell lines and tumor cells from patients. In cancer cells, transfection of lv-miR-100 was able to upregulate endogenous expression of miR-100, inhibited cancer cell proliferation, and increased sensitivities to cisplatin. Overexpressing miR-100 led to significant inhibition on tumor formation in vivo. Luciferase essay showed FGFR3 was direct target of miR-100. FGFR3 was significantly downregulated by overexpressing miR-100 in pancreatic cancer cells and knocking down FGFR3 by siRNA exerted similar effect as miR-100. Our study demonstrated that miR-100 played an important role in pancreatic cancer development, possibly through targeting FGFR3. It may become a new therapeutic target for gene therapy in patients suffered from pancreatic cancer.

MicroRNA-100 regulates pancreatic cancer cells growth and sensitivity to chemotherapy through targeting FGFR3

We intended to investigate the role of microRNA 100 (miR-100) in regulating pancreatic cancer cells' growth in vitro and tumor development in vivo. QTR-PCR was used to examine the expression of miR-100 in pancreatic cancer cell lines and tumor cells from human patients. Lentivirual vector containing miR-100 mimics (lv-miR-100) was used to overexpress miR-100 in MIA PaCa-2 and FCPAC-1 cells. The effects of overexpressing miR-100 on pancreatic cancer cell proliferation and chemosensitivity to cisplatin were examined by cell proliferation essay in vitro. MIA PaCa-2 cells with endogenously overexpressed miR-100 were transplanted into null mice to examine tumor growth in vivo. The predicted target of miR-100, fibroblast growth factor receptor 3 (FGFR3), was downregulated by siRNA to examine its effect on pancreatic cancer cells. We found miR-100 was markedly underexpressed in both pancreatic cancer cell lines and tumor cells from patients. In cancer cells, transfection of lv-miR-100 was able to upregulate endogenous expression of miR-100, inhibited cancer cell proliferation, and increased sensitivities to cisplatin. Overexpressing miR-100 led to significant inhibition on tumor formation in vivo. Luciferase essay showed FGFR3 was direct target of miR-100. FGFR3 was significantly downregulated by overexpressing miR-100 in pancreatic cancer cells and knocking down FGFR3 by siRNA exerted similar effect as miR-100. Our study demonstrated that miR-100 played an important role in pancreatic cancer development, possibly through targeting FGFR3. It may become a new therapeutic target for gene therapy in patients suffered from pancreatic cancer.

Converting potent indeno[1,2-b]indole inhibitors of protein kinase CK2 into selective inhibitors of the breast cancer resistance protein ABCG2

A series of indeno[1,2-b]indole-9,10-dione derivatives were synthesized as human casein kinase II (CK2) inhibitors. The most potent inhibitors contained a N(5)-isopropyl substituent on the C-ring. The same series of compounds was found to also inhibit the breast cancer resistance protein ABCG2 but with totally different structure-activity relationships: a N(5)-phenethyl substituent was critical, and additional hydrophobic substituents at position 7 or 8 of the D-ring or a methoxy at phenethyl position ortho or meta also contributed to inhibition. The best ABCG2 inhibitors, such as 4c, 4h, 4i, 4j, and 4k, behaved as very weak inhibitors of CK2, whereas the most potent CK2 inhibitors, such as 4a, 4p, and 4e, displayed limited interaction with ABCG2. It was therefore possible to convert, through suitable substitutions of the indeno[1,2-b]indole-9,10-dione scaffold, potent CK2 inhibitors into selective ABCG2 inhibitors and vice versa. In addition, some of the best ABCG2 inhibitors, which displayed a very low cytotoxicity, thus giving a high therapeutic ratio, and appeared not to be transported, constitute promising candidates for further investigations.

p21-activated kinase 7 is an oncogene in human osteosarcoma

p21-activated kinase 7 (PAK7), also named as PAK5, is a member of Rac/Cdc42-associated Ser/Thr protein kinases. It is overexpressed in some types of cancer such as colorectal and pancreatic cancers. However, the expression status and biological function of PAK7 in osteosarcoma are still ambiguous. To evaluate the expression levels of PAK7 in osteosarcoma tissues and cell lines, immunohistochemistry was used. To investigate the role of PAK7 in cell proliferation, apoptosis and tumorigenicity in vitro and vivo, a recombinant lentivirus expressing PAK7 short hairpin RNA (Lv-shPAK7) was developed and transfected into Saos-2 cells. The silencing effect of PAK7 was confirmed by quantitative real-time PCR (qRT-PCR) and Western blot technique. PAK7 was overexpressed in osteosarcoma tissue and cell line. By knocking-down of PAK7, the proliferation and colony formation of Saos-2 cells were inhibited and apoptosis enhanced significantly. The in vivo tumorigenic ability in xenograft model of Saos-2 cells was also notably inhibited when PAK7 was knocked down. Our results imply that PAK7 promotes cell proliferation and tumorigenesis and may be an attractive candidate for the therapeutic target of osteosarcoma.

Advances in nanocrystallography as a proteomic tool

In order to overcome the difficulties and hurdles too much often encountered in crystallizing a protein with the conventional techniques, our group has introduced the innovative Langmuir-Blodgett (LB)-based crystallization, as a major advance in the field of both structural and functional proteomics, thus pioneering the emerging field of the so-called nanocrystallography or nanobiocrystallography. This approach uniquely combines protein crystallography and nanotechnologies within an integrated, coherent framework that allows one to obtain highly stable protein crystals and to fully characterize them at a nano- and subnanoscale. A variety of experimental techniques and theoretical/semi-theoretical approaches, ranging from atomic force microscopy, circular dichroism, Raman spectroscopy and other spectroscopic methods, microbeam grazing-incidence small-angle X-ray scattering to in silico simulations, bioinformatics, and molecular dynamics, has been exploited in order to study the LB-films and to investigate the kinetics and the main features of LB-grown crystals. When compared to classical hanging-drop crystallization, LB technique appears strikingly superior and yields results comparable with crystallization in microgravity environments. Therefore, the achievement of LB-based crystallography can have a tremendous impact in the field of industrial and clinical/therapeutic applications, opening new perspectives for personalized medicine. These implications are envisaged and discussed in the present contribution.

Flavonoid apigenin modified gene expression associated with inflammation and cancer and induced apoptosis in human pancreatic cancer cells through inhibition of GSK-3β/NF-κB signaling cascade

SCOPE

The objective was to examine the inhibitory effects of citrus fruit bioactive compounds on BxPC-3 and PANC-1 human pancreatic cancer cells, focusing on the antiproliferative mechanism of action of the flavonoid apigenin related to the glycogen synthase kinase-3β/nuclear factor kappa B signaling pathway.

METHODS AND RESULTS

Flavonoids, limonoids, phenolic acids, and ascorbic acid were tested for cytotoxic effects on BxPC-3 and PANC-1 cells; apigenin was the most potent (IC50 = 23 and 12 μM for 24 and 48 h for BxPC-3 and IC50 = 71 and 41 μM for 24 and 48 h for PANC-1). Apigenin induced pancreatic cell death through inhibition of the glycogen synthase kinase-3β/nuclear factor kappa B signaling pathway. Apigenin arrested cell cycle at G2 /M phase (36 and 32% at 50 μM for BxPC-3 and PANC-1, respectively) with concomitant decrease in the expression of cyclin B1. Apigenin activated the mitochondrial pathway of apoptosis (44 and 14% at 50 μM for BxPC-3 and PANC-1, respectively) and modified the expression of apoptotic proteins. Apigenin highly upregulated the expression of cytokine genes IL17F (114.2-fold), LTA (33.1-fold), IL17C (23.2-fold), IL17A (11.3-fold), and IFNB1 (8.9-fold) in BxPC-3 cells, which potentially contributed to the anticancer properties.

CONCLUSION

Flavonoids have a protective role in pancreatic cancer tumorigenesis.

Inhibition of CK2 enhances UV-triggered apoptotic cell death in lung cancer cell lines

Lung cancer is a high-grade malignancy with poor 5 year-survival rates that remains incurable with current therapies. Different cellular stresses, including antitumor agents, ionizing radiation and ultraviolet (UV) light, can induce apoptosis and activate signaling pathways. UV has multiple effects on tumor cells, including DNA damage, and increases the expression of some genes involved in tumor cell apoptosis and DNA repair. It has been reported that UV can also activate casein kinase 2 (CK2). CK2, a Ser/Thr protein kinase, has been reported to be frequently overexpressed in various types of human cancer, including lung cancer, and is associated with tumor development. Thus, combination of UV and CK2 inhibitors may be a new strategy for the treatment of lung cancer. Our results demonstrated that inhibition of CK2a through CK2 siRNA or a CK2 inhibitor [(4,5,6,7-tetrabromobenzotriazole (TBB)] enhances the decrease in cell viability of lung cancer cells (A549 and H2030) induced by UV. Western blot analysis demonstrated that the combination increased the expression of apoptotic protein markers cytochrome c and the cleavage of poly ADP-ribose polymerase (PARP) and caspase-3. Furthermore, our results indicated that UV decreased the expression of the tumor suppressor protein PML through activation of CK2. Inhibition of CK2 by CK2 siRNA and TBB can recover the reduction of PML induced by UV. Collectively, these results demonstrate the significant apoptosis of lung cancer cells induced by combination treatment of the CK2 inhibitor and UV radiation. CK2 enhanced cell apoptosis by UV radiation may due, at least partly, to recover the expression of PML. These findings warrant the clinical testing of CK2 inhibitors which, when used in conjunction with DNA-damaging agents such as radiation, may be an effective cancer therapeutic strategy.

Aberrant glycogen synthase kinase 3β in the development of pancreatic cancer

Development and progression of pancreatic cancer involves general metabolic disorder, local chronic inflammation, and multistep activation of distinct oncogenic molecular pathways. These pathologic processes result in a highly invasive and metastatic tumor phenotype that is a major obstacle to curative surgical intervention, infusional gemcitabine-based chemotherapy, and radiation therapy. Many clinical trials with chemical compounds and therapeutic antibodies targeting growth factors, angiogenic factors, and matrix metalloproteinases have failed to demonstrate definitive therapeutic benefits to refractory pancreatic cancer patients. Glycogen synthase kinase 3β (GSK3β), a serine/threonine protein kinase, has emerged as a therapeutic target in common chronic and progressive diseases, including cancer. Here we review accumulating evidence for a pathologic role of GSK3β in promoting tumor cell survival, proliferation, invasion, and resistance to chemotherapy and radiation in pancreatic cancer. We also discuss the putative involvement of GSK3β in mediating metabolic disorder, local inflammation, and molecular alteration leading to pancreatic cancer development. Taken together, we highlight potential therapeutic as well as preventive effects of GSK3β inhibition in pancreatic cancer.

Glycogen synthase kinase 3β inhibition sensitizes pancreatic cancer cells to gemcitabine

BACKGROUND

Pancreatic cancer is obstinate and resistant to gemcitabine, a standard chemotherapeutic agent for the disease. We previously showed a therapeutic effect of glycogen synthase kinase-3β (GSK3β) inhibition against gastrointestinal cancer and glioblastoma. Here, we investigated the effect of GSK3β inhibition on pancreatic cancer cell sensitivity to gemcitabine and the underlying molecular mechanism.

METHODS

Expression, phosphorylation, and activity of GSK3β in pancreatic cancer cells (PANC-1) were examined by Western immunoblotting and in vitro kinase assay. The combined effect of gemcitabine and a GSK3β inhibitor (AR-A014418) against PANC-1 cells was examined by isobologram and PANC-1 xenografts in mice. Changes in gene expression in PANC-1 cells following GSK3β inhibition were studied by cDNA microarray and reverse transcription (RT)-PCR.

RESULTS

PANC-1 cells showed increased GSK3β expression, phosphorylation at tyrosine 216 (active form), and activity compared with non-neoplastic HEK293 cells. Administration of AR-A014418 at pharmacological doses attenuated proliferation of PANC-1 cells and xenografts, and significantly sensitized them to gemcitabine. Isobologram analysis determined that the combined effect was synergistic. DNA microarray analysis detected GSK3β inhibition-associated changes in gene expression in gemcitabine-treated PANC-1 cells. Among these changes, RT-PCR and Western blotting showed that expression of tumor protein 53-induced nuclear protein 1, a gene regulating cell death and DNA repair, was increased by gemcitabine treatment and substantially decreased by GSK3β inhibition.

CONCLUSIONS

The results indicate that GSK3β inhibition sensitizes pancreatic cancer cells to gemcitabine with altered expression of genes involved in DNA repair. This study provides insight into the molecular mechanism of gemcitabine resistance and thus a new strategy for pancreatic cancer chemotherapy.

Gold-containing indoles as anticancer agents that potentiate the cytotoxic effects of ionizing radiation

This report describes the design and application of several distinct gold-containing indoles as anticancer agents. When used individually, all gold-bearing compounds display cytostatic effects against leukemia and adherent cancer cell lines. However, two gold-bearing indoles show unique behavior by increasing the cytotoxic effects of clinically relevant levels of ionizing radiation. Quantifying the amount of DNA damage demonstrates that each gold-indole enhances apoptosis by inhibiting DNA repair. Both Au(I)-indoles were tested for inhibitory effects against various cellular targets including thioredoxin reductase, a known target of several gold compounds, and various ATP-dependent kinases. While neither compound significantly inhibits the activity of thioreoxin reductase, both showed inhibitory effects against several kinases associated with cancer initiation and progression. The inhibition of these kinases provides a possible mechanism for the ability of these Au(I)-indoles to potentiate the cytotoxic effects of ionizing radiation. Clinical applications of combining Au(I)-indoles with ionizing radiation are discussed as a new strategy to achieve chemosensitization of cancer cells.

DJ-1 promotes invasion and metastasis of pancreatic cancer cells by activating SRC/ERK/uPA

A major hallmark of pancreatic ductal adenocarcinoma (PDAC) is extensive local tumor invasion and early systemic dissemination. DJ-1 has been shown to prevent cell death via the Akt pathway, thereby playing an important role in cancer progression and Parkinson's disease development. Here, we investigated the role of DJ-1 in tumor invasion and metastasis of pancreatic cancer and showed that DJ-1 is upregulated in 68.5% of pancreatic cancer specimens, correlated with tumor stage and predictive of short overall survival. Knockdown of DJ-1 expression in two PDAC cell lines reduced cell migration and invasion potential in vitro and inhibited metastasis in vivo. Knockdown of DJ-1 led to cytoskeleton disruption and diminished urokinase plasminogen activator (uPA) activity and expression, without affecting plasminogen activator inhibitor-1 and uPA receptor (uPAR) expression. All these effects were reversed by restoration of DJ-1 expression. In determining the pathway through which DJ-1 regulated cell migration and invasion, DJ-1 was found not to regulate Akt phosphorylation. Rather, it promoted extracellular signal-regulated kinase (ERK) and SRC phosphorylation. Inhibition of the ERK pathway in PDAC mimicked the effects of DJ-1 on cell migration, invasion, actin cytoskeleton and uPA/uPAR system and abolished the effects on promoting PDAC cell invasion and migration. These data represent the first identification of an important function of DJ-1, which is to regulate the invasion and metastasis properties of PDAC through the ERK/uPA cascade.

Targeting FGFR/PDGFR/VEGFR impairs tumor growth, angiogenesis, and metastasis by effects on tumor cells, endothelial cells, and pericytes in pancreatic cancer

Activation of receptor tyrosine kinases, such as fibroblast growth factor receptor (FGFR), platelet-derived growth factor receptor (PDGFR), and VEGF receptor (VEGFR), has been implicated in tumor progression and metastasis in human pancreatic cancer. In this study, we investigated the effects of TKI258, a tyrosine kinase inhibitor to FGFR, PDGFR, and VEGFR on pancreatic cancer cell lines (HPAF-II, BxPC-3, MiaPaCa2, and L3.6pl), endothelial cells, and vascular smooth muscle cells (VSMC). Results showed that treatment with TKI258 impaired activation of signaling intermediates in pancreatic cancer cells, endothelial cells, and VSMCs, even upon stimulation with FGF-1, FGF-2, VEGF-A, and PDGF-B. Furthermore, blockade of FGFR/PDGFR/VEGFR reduced survivin expression and improved activity of gemcitabine in MiaPaCa2 pancreatic cancer cells. In addition, motility of cancer cells, endothelial cells, and VSMCs was reduced upon treatment with TKI258. In vivo, therapy with TKI258 led to dose-dependent inhibition of subcutaneous (HPAF-II) and orthotopic (L3.6pl) tumor growth. Immunohistochemical analysis revealed effects on tumor cell proliferation [bromodeoxyuridine (BrdUrd)] and tumor vascularization (CD31). Moreover, lymph node metastases were significantly reduced in the orthotopic tumor model when treatment was initiated early with TKI258 (30 mg/kg/d). In established tumors, TKI258 (30 mg/kg/d) led to significant growth delay and improved survival in subcutaneous and orthotopic models, respectively. These data provide evidence that targeting FGFR/PDFGR/VEGFR with TKI258 may be effective in human pancreatic cancer and warrants further clinical evaluation.

Serum DJ-1 as a diagnostic marker and prognostic factor for pancreatic cancer

OBJECTIVE

DJ-1 is an oncoprotein secreted by cancer cells. Therefore, it might be a diagnostic or prognostic biomarker for pancreatic cancer (PC).

METHODS

The study involved 47 patients with PC, 43 with chronic pancreatitis, and 40 healthy subjects. We assayed the serum level of DJ-1 and the conventional tumor marker carbohydrate antigen 19-9 (CA 19-9) to define the diagnostic and prognostic value of DJ-1 for PC.

RESULTS

Serum DJ-1 level was elevated in patients with PC compared with those with chronic pancreatitis and healthy individuals. The area under the curve (AUC) of serum DJ-1 was higher than CA 19-9 (DJ-1 vs. CA19-9, 0.8735 ± 0.0356 vs. 0.6647 ± 0.0572 ng/mL), and an 87.5% sensitivity was reached with a combination of serum DJ-1 and CA19-9. No association of serum DJ-1 level with tumor node metastasis (TNM) classification or tumor resectability was found. However, after resection, the median serum DJ-1 level was decreased from 2.00 to 0.78 ng/mL. In addition, higher serum DJ-1 was correlated with shorter overall survival as analyzed by both Kaplan-Meier test (P = 0.018) and COX regression analysis (P = 0.013). The median overall survival time of PC patients with serum DJ-1 level greater than or equal to 2.06 ng/mL was 7.00 ± 1.11 months, whereas that of patients with lower DJ-1 levels was 13.0 ± 2.5 months.

CONCLUSIONS

These findings indicate the potential clinical significance for serum DJ-1 level to be used for the diagnosis and prognosis prediction of patients with PC.

Metabolic disorder, inflammation, and deregulated molecular pathways converging in pancreatic cancer development: implications for new therapeutic strategies

Pancreatic cancer develops and progresses through complex, cumulative biological processes involving metabolic disorder, local inflammation, and deregulated molecular pathways. The resulting tumor aggressiveness hampers surgical intervention and renders pancreatic cancer resistant to standard chemotherapy and radiation therapy. Based on these pathologic properties, several therapeutic strategies are being developed to reverse refractory pancreatic cancer. Here, we outline molecular targeting therapies, which are primarily directed against growth factor receptor-type tyrosine kinases deregulated in tumors, but have failed to improve the survival of pancreatic cancer patients. Glycogen synthase kinase-3β (GSK3β) is a member of a serine/threonine protein kinase family that plays a critical role in various cellular pathways. GSK3β has also emerged as a mediator of pathological states, including glucose intolerance, inflammation, and various cancers (e.g., pancreatic cancer). We review recent studies that demonstrate the anti-tumor effects of GSK3β inhibition alone or in combination with chemotherapy and radiation. GSK3β inhibition may exert indirect anti-tumor actions in pancreatic cancer by modulating metabolic disorder and inflammation.

Advances in pancreatic cancer detection

Pancreatic cancer represents a major challenge for research studies and clinical management. No specific tumor marker for the diagnosis of pancreatic cancer exists. Therefore, extensive genomic, transcriptomic, and proteomic studies are being developed to identify candidate markers for use in high-throughput systems capable of large cohort screening. Understandably, the complex pathophysiology of pancreatic cancer requires sensitive and specific biomarkers that can improve both early diagnosis and therapeutic monitoring. The lack of a single diagnostic marker makes it likely that only a panel of biomarkers is capable of providing the appropriate combination of high sensitivity and specificity. Biomarker discovery using novel technology can improve prognostic upgrading and pinpoint new molecular targets for innovative therapy.