Heat Shock Proteins: A Potential Anticancer Target

Genetic Variants of CLEC4E and BIRC3 in Damage-Associated Molecular Patterns-Related Pathway Genes Predict Non-Small Cell Lung Cancer Survival

Accumulating evidence supports a role of various damage-associated molecular patterns (DAMPs) in progression of lung cancer, but roles of genetic variants of the DAMPs-related pathway genes in lung cancer survival remain unknown. We investigated associations of 18,588 single-nucleotide polymorphisms (SNPs) in 195 DAMPs-related pathway genes with non-small cell lung cancer (NSCLC) survival in a subset of genotyping data for 1,185 patients from the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial and validated the findings in another independent subset of genotyping data for 984 patients from Harvard Lung Cancer Susceptibility Study. We performed multivariate Cox proportional hazards regression analysis, followed by expression quantitative trait loci (eQTL) analysis, Kaplan-Meier survival analysis and bioinformatics functional prediction. We identified that two SNPs (i.e., CLEC4E rs10841847 G>A and BIRC3 rs11225211 G>A) were independently associated with NSCLC overall survival, with adjusted allelic hazards ratios of 0.89 (95% confidence interval=0.82-0.95 and P=0.001) and 0.82 (0.73-0.91 and P=0.0003), respectively; so were their combined predictive alleles from discovery and replication datasets (P_trend=0.0002 for overall survival). We also found that the CLEC4E rs10841847 A allele was associated with elevated mRNA expression levels in normal lymphoblastoid cells and whole blood cells, while the BIRC3 rs11225211 A allele was associated with increased mRNA expression levels in normal lung tissues. Collectively, these findings indicated that genetic variants of CLEC4E and BIRC3 in the DAMPs-related pathway genes were associated with NSCLC survival, likely by regulating the mRNA expression of the corresponding genes.

Potentiating Therapeutic Effects of Epidermal Growth Factor Receptor Inhibition in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a subset of breast cancer with aggressive characteristics and few therapeutic options. The lack of an appropriate therapeutic target is a challenging issue in treating TNBC. Although a high level expression of epidermal growth factor receptor (EGFR) has been associated with a poor prognosis among patients with TNBC, targeted anti-EGFR therapies have demonstrated limited efficacy for TNBC treatment in both clinical and preclinical settings. However, with the advantage of a number of clinically approved EGFR inhibitors (EGFRis), combination strategies have been explored as a promising approach to overcome the intrinsic resistance of TNBC to EGFRis. In this review, we analyzed the literature on the combination of EGFRis with other molecularly targeted therapeutics or conventional chemotherapeutics to understand the current knowledge and to provide potential therapeutic options for TNBC treatment.

PNSA, a Novel C-Terminal Inhibitor of HSP90, Reverses Epithelial-Mesenchymal Transition and Suppresses Metastasis of Breast Cancer Cells In Vitro

Metastasis accounts for the vast majority of deaths in breast cancer, and novel and effective treatments to inhibit cancer metastasis remain urgently developed. The expression level of heat shock protein 90 (HSP90) in invasive breast cancer tissue is higher than in adjacent non-cancerous tissue. In the present study, we investigated the inhibitory effect of penisuloxazin A (PNSA), a novel C- terminal inhibitor of HSP90, on metastasis of breast cancer cells and related mechanism in vitro. We found that PNSA obviously affected adhesion, migration, and invasion of triple-negative breast cancer (TNBC) MDA-MB-231 cells and Trastuzumab-resistant JIMT-1 cells. Furthermore, PNSA was capable of reversing epithelial-mesenchymal transformation (EMT) of MDA-MB-231 cells with change of cell morphology. PNSA increases E-cadherin expression followed by decreasing amounts of N-cadherin, vimentin, and matrix metalloproteinases9 (MMP9) and proteolytic activity of matrix metalloproteinases2 (MMP2) and MMP9. Comparatively, the N-terminal inhibitor of HSP90 17-allyl-17-demethoxygeldanamycin (17-AAG) had no effect on EMT of MDA-MB-231 cells. PNSA was uncovered to reduce the stability of epidermal growth factor receptor (EGFR) and fibroblast growth factor receptor (FGFR) proteins and thereby inhibiting their downstream signaling transductions by inhibition of HSP90. In addition, PNSA reduced the expression of programmed cell death-ligand 1 (PD-L1) to promote natural killer (NK) cells to kill breast cancer cells with a dose far less than that of cytotoxicity to NK cell itself, implying the potential of PNSA to enhance immune surveillance against metastasis in vivo. All these results indicate that PNSA is a promising anti-metastasis agent worthy of being studied in the future.

Differential expression of heat shock proteins and activation of mitogen-activated protein kinases in A549 alveolar epithelial cells exposed to cigarette smoke extract

NEW FINDINGS

What is the central question of this study? What is the effect of cigarette smoke on cell death, oxidative damage, expression of heat shock proteins (HSPs) and activation of mitogen-activated protein kinases (MAPKs) in A549 alveolar epithelial cells? What is the main finding and its importance? Cigarette smoke induces cytotoxicity and oxidative damage to A549 cells, increases expression of different HSPs and activates MAPK signalling pathways. This could be related to inflammatory response and apoptosis observed in lungs of patients with smoking-related diseases.

ABSTRACT

Cigarette smoking is one of the main risk factors for development of chronic obstructive pulmonary disease (COPD). We previously reported that cigarette smoke (CS) induces damage to proteins and their ineffective degradation. Here, we hypothesize that CS could induce oxidative stress and cytotoxicity in lung epithelial cells through alterations of heat shock protein (HSP) expression and mitogen-activated protein kinase (MAPK) signalling pathways. We exposed A549 alveolar epithelial cells to various concentrations of cigarette smoke extract (CSE). Higher concentrations of CSE caused apoptosis of A549 cells after 4 h, while after 24 h cell viability was decreased, and lactate dehydrogenase in cell culture medium was increased as well as the number of necrotic cells. Concentrations of malondialdehyde (MDA) were elevated, while total thiol groups were decreased. Changes in the expression of HSPs (HSP70, HSP32 and HSP27) were time-dependent. After 6 h, CSE caused an increase in the expression of HSP70 and HSP32, while after 8 h all examined HSPs were up-regulated and remained increased up to 48 h. Treatment of A549 cells with CSE stimulated phosphorylation of extracellular signal-regulated kinase and p38 in a dose-dependent manner, while c-Jun N-terminal kinase activation was not detected. By using specific inhibitors, we demonstrated that MAPKs and HSPs interplay in CSE effects. In conclusion, our results show that MAPKs and HSPs are involved in the mechanism underlying CSE-induced cytotoxicity and oxidative damage to A549 alveolar epithelial cells. These processes could be related to inflammatory response and apoptosis observed in lungs of patients with smoking-related diseases, such as COPD.

Clinical and prognostic value of chaperonin containing T-complex 1 subunit 3 in hepatocellular carcinoma: A Study based on microarray and RNA-sequencing with 4272 cases

Liver cancer is one of the few tumors with a steadily increasing morbidity and mortality; hepatocellular carcinoma (HCC) is the most common type of primary liver cancer. We combined the expression profiles of Chaperonin Containing T-complex 1 Subunit 3 (CCT3) in HCC tissues based on microarray and RNA-sequencing data. The CCT3 expression levels were extracted and examined based on 421 samples from The Cancer Genome Atlas (TCGA) (HCC, n = 371; non-HCC, n = 50) and 3851 samples from 31 microarray or RNA-sequencing datasets (HCC, n = 1975; non-tumor = 1876). We used a variety of meta-analytic methods, including SMD forest maps, sensitivity analysis, subgroup analysis and sROC curves, to confirm the final results. Meanwhile, database-derived immunohistochemistry data was used for validation. We also further explained the potential mechanism of CCT3 in HCC through signal pathway analyses and PPI network construction with the CCT3 co-expressed genes. The mRNA and protein expression of CCT3 in HCC tissues were higher than in non-HCC tissues. The expression of CCT3 differed between groups when grouped according to clinicopathological parameters, such as race, family history, and histological grade. The results of standardised mean difference (SMD) forest map and summary receiver operating characteristic (sROC) curve revealed that CCT3 was highly expressed in HCC tissues and had a high ability to distinguish between cancer tissues and non-cancer tissues. The main form of CCT3 gene alteration in HCC was mRNA up-regulation and amplification (23%), and the most common mutation type was missense. The mRNA expression of CCT3 in HCC was negatively correlated with DNA methylation. According to the Kyoto Encyclopedia of Genes and Genomes pathway analysis, CCT3 can influence HCC occurrence and development through cell cycle and DNA replication pathways. In summary, this study carries out the staging and prognostic analysis of HCC. It suggests that CCT3 might play an important part in the tumorigenesis and progression of HCC and may have a certain prognostic value in HCC. Moreover, CCT3 might represent a promising biomarker for HCC.

A novel chalcone-based molecule, BDP inhibits MDA‑MB‑231 triple-negative breast cancer cell growth by suppressing Hsp90 function

Triple-negative breast cancer (TNBC) is a molecularly diverse and heterogeneous disease and the molecular heterogeneity of TNBC increases the difficulty in improving survival rates. To date, therapeutic approaches for the treatment of TNBC such as hormonal chemotherapy and trastuzumab-based therapy have been limited by the lack of target receptors such as estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (Her2), emphasizing the urgent need for identifying new therapeutic options. In this regard, heat shock protein 90 (Hsp90) has emerged as an attractive therapeutic target for TNBC. Hsp90 plays a central role in regulating correct folding, stability, and function of numerous oncogenic proteins. In the present study, we evaluated the in vitro effect of a small molecule Hsp90 inhibitor, (E)-3-(2-bromo-3,4,5-trimethoxyphenyl)-1-(2,4-dihydroxyphenyl)prop-2-en-1-one (BDP) on TNBC cell line, MDA‑MB‑231. This study indicated that BDP efficiently inhibited the growth of MDA‑MB‑231 cells in a dose- and time-dependent manner. BDP induced overall degradation of multiple oncogenic proteins including EGFR, Her2, Met, Akt, c‑Raf, and Cdk4, consequently leading to apoptotic cell death. The flow cytometric analysis revealed that BDP promoted cell cycle arrest at G2/M phases. Moreover, BDP treatment attenuated the migration of MDA‑MB‑231 cells and impaired MMP9 activity, which are essential processes for tumor metastasis. Collectively, BDP represents a new class of Hsp90 inhibitor and shows therapeutic potential for TNBC treatment.

Anti-Inflammatory Mechanism Involved in Pomegranate-Mediated Prevention of Breast Cancer: the Role of NF-κB and Nrf2 Signaling Pathways

Pomegranate (Punica granatum L.), a nutrient-rich unique fruit, has been used for centuries for the prevention and treatment of various inflammation-driven diseases. Based on our previous study, a characterized pomegranate emulsion (PE) exhibited a striking inhibition of dimethylbenz(a)anthracene (DMBA)-initiated rat mammary tumorigenesis via antiproliferative and apoptosis-inducing mechanisms. The objective of the present work is to investigate the anti-inflammatory mechanism of action of PE during DMBA rat mammary carcinogenesis by evaluating the expression of cyclooxygenase-2 (COX-2), heat shock protein 90 (HSP90), nuclear factor-κB (NF-κB) and nuclear factor erythroid 2p45 (NF-E2)-related factor 2 (Nrf2). Mammary tumor samples were harvested from our previous chemopreventive study in which PE (0.2–5.0 g/kg) was found to reduce mammary tumorigenesis in a dose-dependent manner. The expressions of COX-2, HSP90, NF-κB, inhibitory κBα (IκBα) and Nrf2 were detected by immunohistochemical techniques. PE decreased the expression of COX-2 and HSP90, prevented the degradation of IκBα, hindered the translocation of NF-κB from cytosol to nucleus and increased the expression and nuclear translocation of Nrf2 during DMBA-induced mammary tumorigenesis. These findings, together with our previous results, indicate that PE-mediated prevention of DMBA-evoked mammary carcinogenesis may involve anti-inflammatory mechanisms through concurrent but differential regulation of two interrelated molecular pathways, namely NF-κB and Nrf2 signaling.

Comparative protein profiling of B16 mouse melanoma cells susceptible and non-susceptible to alphavirus infection: Effect of the tumor microenvironment

Alphavirus vectors are promising tools for cancer treatment. However, relevant entry mechanisms and interactions with host cells are still not clearly understood. The first step toward a more effective therapy is the identification of novel intracellular alterations that could be associated with cancer aggressiveness and could affect the therapeutic potential of these vectors. In this study, we observed that alphaviruses efficiently infected B16 mouse melanoma tumors/tumor cells in vivo, whereas their transduction efficiency in B16 cells under in vitro conditions was blocked. Therefore, we further aimed to understand the mechanisms pertaining to the differential transduction efficacy of alphaviruses in B16 tumor cells under varying growth conditions. We hypothesized that the tumor microenvironment might alter gene expression in B16 cells, leading to an up-regulation of the expression of virus-binding receptors or factors associated with virus entry and replication. To test our hypothesis, we performed a proteomics analysis of B16 cells cultured in vitro and of B16 cells isolated from tumors, and we identified 277 differentially regulated proteins. A further in-depth analysis to identify the biological and molecular functions of the detected proteins revealed a set of candidate genes that could affect virus infectivity. Importantly, we observed a decrease in the expression of interferon α (IFN-α) in tumor-isolated cells that resulted in the suppression of several IFN-regulated genes, thereby abrogating host cell antiviral defense. Additionally, differences in the expression of genes that regulate cytoskeletal organization caused significant alterations in cell membrane elasticity. Taken together, our findings demonstrated favorable intracellular conditions for alphavirus transduction/replication that occurred during tumor transformation. These results pave the way for optimizing the development of strategies for the application of alphaviral vectors as a potent cancer therapy.

Molecular chaperone CCT3 supports proper mitotic progression and cell proliferation in hepatocellular carcinoma cells

CCT3 was one of the subunits of molecular chaperone CCT/TRiC complex, which plays a central role in maintaining cellular proteostasis. We demonstrated that expressions of CCT3 mRNA and protein are highly up-regulated in hepatocellular carcinoma (HCC) tissues, and high level of CCT3 is correlated with poor survival in cancer patients. In HCC cell lines, CCT3 depletion suppresses cell proliferation by inducing mitotic arrest at prometaphase and apoptosis eventually. We also identified CCT3 as a novel regulator of spindle integrity and as a requirement for proper kinetochore-microtubule attachment during mitosis. Moreover, we found that CCT3 depletion sensitizes HCC cells to microtubule destabilizing drug Vincristine. Collectively, our study suggests that CCT3 is indispensible for HCC cell proliferation, and provides a potential drug target for treatment of HCC.

17-AAG suppresses growth and invasion of lung adenocarcinoma cells via regulation of the LATS1/YAP pathway

The large tumour suppressor 1 (LATS1) signalling network has been proved to be an essential regulator within the cell, participating in multiple cellular phenotypes. However, it is unclear concerning the clinical significance of LATS1 and the regulatory mechanisms of 17-Allylamino-17- demethoxygeldanamycin (17-AAG) in lung adenocarcinoma (LAC). The aim of the present study was to investigate the correlation of LATS1 and yes-associated protein (YAP) expression with clinicopathological characteristics in LAC patients, and the effects of 17-AAG on biological behaviours of LAC cells. Subcutaneous LAC tumour models were further established to observe the tumour growth in nude mice. The results showed that the positive expression of LATS1 was significantly lowered (26.7% versus 68.0%, P < 0.001), while that of YAP was elevated (76.0% versus 56.0%, P + 0.03) in LAC tissues compared to the adjacent non-cancerous tissues; LAST1 expression was negatively correlated with YAP expression (r + 0.432, P < 0.001) and lymphatic invasion of the tumour (P + 0.015). In addition, 17-AAG inhibited proliferation and invasion, and induced cell apoptosis and cycle arrest in LAC cells together with increased expression of E-cadherin and p-LATS1, and decreased expression of YAP and connective tissue growth factor. Tumour volumes and weight were much smaller in 17-AAG-treated groups than those in untreated group (P < 0.01). Taken together, our findings indicate that decreased expression of LATS1 is associated with lymphatic invasion of LAC, and 17-AAG suppresses growth and invasion of LAC cells via regulation of the LATS1/YAP pathway in vitro and in vivo, suggesting that we may provide a promising therapeutic strategy for the treatment of human LAC.

Role of TRP channels in the induction of heat shock proteins (Hsps) by heating skin

Transient receptor potential (TRP) channels in skin are crucial for achieving temperature sensitivity to maintain internal temperature balance and thermal homeostasis, as well as to protect skin cells from environmental stresses such as infrared (IR) or near-infrared (NIR) radiation via heat shock protein (Hsp) production. However, the mechanisms by which IR and NIR activate TRP channels and produce Hsps intracellularly have been independently reported. In this review, we discuss the relationship between TRP channel activation and Hsp production, and introduce the roles of several skin TRP channels in the regulation of HSP production by IR and NIR exposure.

Trianthema portulacastrum Linn. displays anti-inflammatory responses during chemically induced rat mammary tumorigenesis through simultaneous and differential regulation of NF-κB and Nrf2 signaling pathways

Trianthema portulacastrum, a medicinal and dietary plant, has gained substantial importance due to its various pharmacological properties, including anti-inflammatory and anticarcinogenic activities. We have recently reported that a characterized T. portulacastrum extract (TPE) affords a considerable chemoprevention of 7,12-dimethylbenz(a)anthracene (DMBA)-induced rat mammary tumorigenesis though the underlying mechanisms are not completely understood. The objective of this study was to investigate anti-inflammatory mechanisms of TPE during DMBA mammary carcinogenesis in rats by monitoring cyclooxygenase-2 (COX-2), heat shock protein 90 (HSP90), nuclear factor-kappaB (NF-κB) and nuclear factor erythroid 2-related factor 2 (Nrf2). Mammary tumors were harvested from our previous study in which TPE (50-200 mg/kg) was found to inhibit mammary tumorigenesis in a dose-response manner. The expressions of intratumor COX-2, HSP90, NF-κB, inhibitory kappaB-alpha (IκBα) and Nrf2 were determined by immunohistochemistry. TPE downregulated the expression of COX-2 and HSP90, blocked the degradation of IκBα, hampered the translocation of NF-κB from cytosol to nucleus and upregulated the expression and nuclear translocation of Nrf2 during DMBA mammary carcinogenesis. These results in conjunction with our previous findings suggest that TPE prevents DMBA-induced breast neoplasia by anti-inflammatory mechanisms mediated through simultaneous and differential modulation of two interconnected molecular circuits, namely NF-κB and Nrf2 signaling pathways.

In vitro synergistic action of geldanamycin- and docetaxel-containing HPMA copolymer-RGDfK conjugates against ovarian cancer

HPMA copolymer-RGDfK (HPMA-RGDfK) conjugates bearing either aminohexylgeldanamycin (AHGDM) or docetaxel (DOC) were synthesized and characterized. In vitro stability and binding were evaluated. Cytotoxicity toward ovarian cancer cells was evaluated and the ability of the conjugates to induce cell death was assessed by combination index analysis. Conjugates bearing AHGDM were more stable and exhibited slower drug release than those bearing DOC. Both conjugates demonstrated the ability to bind to avb3 integrins. In combination, HPMA-RGDfK conjugates demonstrated marked synergism as compared to their non-targeted counterparts and free drug controls. HPMA-RGDfK conjugates bearing AHGDM and DOC induce synergistic cytotoxicity in vitro, suggesting their potential as a promising combination therapy.

Targeting HSP90 and monoclonal protein trafficking modulates the unfolded protein response, chaperone regulation and apoptosis in myeloma cells

Multiple myeloma is characterized by the production of substantial quantities of monoclonal protein. We have previously demonstrated that select inhibitors of the isoprenoid biosynthetic pathway (IBP) induce apoptosis of myeloma cells via inhibition of Rab geranylgeranylation, leading to disruption of monoclonal protein trafficking and induction of the unfolded protein response (UPR) pathway. Heat-shock protein 90 (HSP90) inhibitors disrupt protein folding and are currently under clinical investigation in myeloma. The effects of combining IBP and HSP90 inhibitors on cell death, monoclonal protein trafficking, the UPR and chaperone regulation were investigated in monoclonal protein-producing cells. An enhanced induction of cell death was observed following treatment with IBP and HSP90 inhibitors, which occurred through both ER stress and non-ER stress pathways. The HSP90 inhibitor 17-AAG abrogated the effects of the IBP inhibitors on intracellular monoclonal protein levels and localization as well as induction of the UPR in myeloma cells. Disparate effects on chaperone expression were observed in myeloma vs amyloid light chain cells. Here we demonstrate that the novel strategy of targeting MP trafficking in concert with HSP90 enhances myeloma cell death via a complex modulation of ER stress, UPR, and cell death pathways.

Hsp90-binding immunophilins as a potential new platform for drug treatment

Immunophilins are proteins that contain a PPIase domain as a family signature. Low-molecular-weight immunophilins were first described associated to immunosuppressive action and protein folding. Recent studies of other members of the family have led to the identification of their participation in basic processes such as protein-protein interactions, signal transduction cascades, cell differentiation, cell cycle progression, metabolic activity, apoptosis mechanisms, microorganisms infection, cancer, neurotrophism and neuroprotection, among several other physiological and pathophysiological processes. Due to all these emerging features, the development of specific ligands for immunophilins appears to have promising perspectives, in particular in the fields of cancer biology and neuroregeneration fields. We review the emerging role of immunophilins in protein transport, transcription regulation, malignancies development and neurotrophic action, in addition to a number of biological properties that transform these proteins in potential targets for novel therapeutic strategies.

Suppression of inflammatory cascade is implicated in methyl amooranin-mediated inhibition of experimental mammary carcinogenesis

Breast cancer represents the second leading cause of cancer-related deaths among women worldwide and preventive therapy could reverse or delay the devastating impact of this disease. Methyl-amooranin (methyl-25-hydroxy-3-oxoolean-12-en-28-oate, AMR-Me), a novel synthetic oleanane triterpenoid, reduced the incidence and burden of 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary tumors in rats through antiproliferative and proapoptotic effects. Since chronic inflammation plays an important role in the pathogenesis of breast cancer and several synthetic oleanane compounds are known potent anti-inflammatory agents, we aim to investigate anti-inflammatory mechanisms of AMR-Me by monitoring various proinflammatory and stress markers, such as cyclooxygenase-2 (COX-2) and heat shock protein 90 (HSP90), and nuclear factor-κB (NF-κB) signaling during DMBA mammary tumorigenesis in rats. Mammary tumors were harvested from a chemopreventive study in which AMR-Me (0.8-1.6 mg/kg) was found to inhibit mammary carcinogenesis in a dose-response manner. The expressions of COX-2, HSP90, NF-κB, and inhibitory κB-α (IκB-α) were determined by immunohistochemistry and reverse transcription-polymerase chain reaction. AMR-Me downregulated the expression of intratumor COX-2 and HSP90, suppressed the degradation of IκB-α, and reduced the translocation of NF-κB from cytosol to nucleus. Our present study provides the first in vivo evidence that NF-κB-evoked inflammatory cascade is a major target of AMR-Me in breast cancer. Our current results together with our previous findings suggest that disruption of NF-κB signaling contributes to anti-inflammatory, antiproliferative, and apoptosis-inducing mechanisms involved in AMR-Me-mediated chemoprevention of rat mammary carcinogenesis. These encouraging mechanistic results coupled with a safety profile should facilitate the clinical development of AMR-Me as breast cancer chemopreventive drug.

Modulation of protein quality control systems by food phytochemicals

There is compelling evidence showing that dietary phytochemicals have exhibited pronounced bioactivities in a number of experimental models. In addition, a variety of epidemiological surveys have demonstrated that frequent ingestion of vegetables and fruits, which contain abundant phytochemicals, lowers the risk of onset of some diseases. However, the action mechanisms by which dietary phytochemicals show bioactivity remain to be fully elucidated and a fundamental question is why this class of chemicals has great potential for regulating health. Meanwhile, maintenance and repair of biological proteins by molecular chaperones, such as heat shock proteins, and clearance of abnormal proteins by the ubiquitin-proteasome system and autophagy play central roles in health, some disease prevention, and longevity. Interestingly, several recent studies have revealed that phytochemicals, including curcumin (yellow pigment in turmeric), resveratrol (phytoalexin in grapes), quercetin (general flavonol in onions and others), and isothiocyanates (preferentially present in cruciferous vegetables, such as broccoli and cabbage), are remarkable regulators of protein quality control systems, suggesting that their physiological and biological functions are exerted, at least in part, through activation of such unique mechanisms. This review article highlights recent findings regarding the effects of representative phytochemicals on protein quality control systems and their possible molecular mechanisms.

Heat shock protein 27 expression is inversely correlated with atrophic gastritis and intraepithelial neoplasia

BACKGROUND

Intestinal-type gastric carcinomas progress through several sequential steps, including atrophic gastritis, intestinal metaplasia, dysplasia, and cancer.

AIM

We investigated heat shock protein 27 (HSP27) expression in gastric neoplasia and background gastric mucosa to assess its involvement in gastric carcinogenesis.

METHODS

We used real-time quantitative polymerase chain reaction to examine HSP27 expression in gastric neoplasias and background gastric mucosae of 30 patients with intraepithelial neoplasias and in gastric mucosae of 30 patients without gastric neoplasia. Immunohistochemical staining was performed on 30 advanced gastric cancer tissues.

RESULTS

HSP27 expression was negatively associated with atrophic gastritis. HSP27 expression in the background gastric mucosa of neoplasia-bearing patients was significantly lower than in the mucosa of those without gastric neoplasia. In tumor necrosis factor α-treated gastric cancer cells, HSP27 knockdown increased cell death and accumulation of the reactive oxygen species that link inflammation to cancer. Poorly differentiated tumors most frequently had high HSP27 levels. Dedifferentiation of cancer cells is associated with an epithelial-mesenchymal transition (EMT) signaling pathway. In gastric cancer MKN-1 cells, HSP27 knockdown upregulated E-cadherin and downregulated vimentin and smooth muscle actin, but this did not occur in MKN-74 cells.

CONCLUSION

HSP27 expression in gastric mucosae is inversely correlated with intraepithelial neoplasia, a probable precursor to gastric cancer, and HSP27 expression in cancer is positively correlated with poor differentiation.

Comparison and validation of genomic predictors for anticancer drug sensitivity

BACKGROUND

An enduring challenge in personalized medicine lies in selecting the right drug for each individual patient. While testing of drugs on patients in large trials is the only way to assess their clinical efficacy and toxicity, we dramatically lack resources to test the hundreds of drugs currently under development. Therefore the use of preclinical model systems has been intensively investigated as this approach enables response to hundreds of drugs to be tested in multiple cell lines in parallel.

METHODS

Two large-scale pharmacogenomic studies recently screened multiple anticancer drugs on over 1000 cell lines. We propose to combine these datasets to build and robustly validate genomic predictors of drug response. We compared five different approaches for building predictors of increasing complexity. We assessed their performance in cross-validation and in two large validation sets, one containing the same cell lines present in the training set and another dataset composed of cell lines that have never been used during the training phase.

RESULTS

Sixteen drugs were found in common between the datasets. We were able to validate multivariate predictors for three out of the 16 tested drugs, namely irinotecan, PD-0325901, and PLX4720. Moreover, we observed that response to 17-AAG, an inhibitor of Hsp90, could be efficiently predicted by the expression level of a single gene, NQO1.

CONCLUSION

These results suggest that genomic predictors could be robustly validated for specific drugs. If successfully validated in patients' tumor cells, and subsequently in clinical trials, they could act as companion tests for the corresponding drugs and play an important role in personalized medicine.

Heat shock proteins in cancer: targeting the 'chaperones'

Heat shock proteins (Hsps) are highly conserved proteins working as molecular chaperones for several cellular proteins essential for normal cell viability and growth, and have numerous cytoprotective roles. The expression of Hsps is induced in response to a wide variety of physiological and environmental stress insults, including anticancer chemotherapy, thus allowing the cell to survive lethal conditions. Cancer cells experience high levels of proteotoxic stress and rely upon stress-response pathways for survival and proliferation, thereby becoming dependent on proteins such as stress-inducible Hsps. Owing to the implication of Hsps in cancer, Hsp inhibition has recently emerged as an interesting potential anticancer strategy. Many natural and synthetic Hsp inhibitors molecular compounds are in development and many are being evaluated as potential cancer therapies. One of the Hsps in particular, Hsp90, has several client proteins and is emerging as a particularly exciting cancer target due to the prospect of simultaneously inhibiting chaperoning of numerous oncogenic proteins. This review describes the function of Hsps focusing on current efforts in exploiting the attributes of Hsps as potential targets for anticancer therapy.

Metastatic gastric cancer - focus on targeted therapies

Gastric cancer (GC) is currently the second leading cause of cancer death worldwide; unfortunately, most patients will present with locally advanced or metastatic disease. Despite recent progress in diagnosis, surgery, chemotherapy, and radiotherapy, prognosis remains poor. A better understanding of GC biology and signaling pathways is expected to improve GC therapy, and the integration of targeted therapies has recently become possible and appears to be promising. This article focuses on anti-Her-2 therapy, specifically trastuzumab, as well as other epidermal growth factor receptor antagonists such as cetuximab, panitumub, matuzumab, nimotzumab, gefitinib, and erlotinib. Additionally, drugs that target angiogenesis pathways are also under investigation, particulary bevacizumab, ramucirumab, sorafenib, sunitinib, and cediranib. Other targeted agents in preclinical or early clinical development include mTOR inhibitors, anti c-MET, polo-like kinase 1 inhibitors, anti-insulin-like growth factor, anti-heat shock proteins, and small molecules targeting Hedgehog signaling.

Short-hairpin RNA-mediated Heat shock protein 90 gene silencing inhibits human breast cancer cell growth in vitro and in vivo

Hsp90 interacts with proteins that mediate signaling pathways involved in the regulation of essential processes such as proliferation, cell cycle control, angiogenesis and apoptosis. Hsp90 inhibition is therefore an attractive strategy for blocking abnormal pathways that are crucial for cancer cell growth. In the present study, the role of Hsp90 in human breast cancer MCF-7 cells was examined by stably silencing Hsp90 gene expression with an Hsp90-silencing vector (Hsp90-shRNA). RT-PCR and Western blot analyses showed that Hsp90-shRNA specifically and markedly down-regulated Hsp90 mRNA and protein expression. NF-kB and Akt protein levels were down-regulated in Hsp90-shRNA transfected cells, indicating that Hsp90 knockout caused a reduction of survival factors and induced apoptosis. Treatment with Hsp90-shRNA significantly increased apoptotic cell death and caused cell cycle arrest in the G1/S phase in MCF-7 cells, as shown by flow cytometry. Silencing of Hsp90 also reduced cell viability, as determined by MTT assay. In vivo experiments showed that MCF-7 cells stably transfected with Hsp90-shRNA grew slowly in nude mice as compared with control groups. In summary, the Hsp90-shRNA specifically silenced the Hsp90 gene, and inhibited MCF-7 cell growth in vitro and in vivo. Possible molecular mechanisms underlying the effects of Hsp90-shRNA include the degradation of Hsp90 breast cancer-related client proteins, the inhibition of survival signals and the upregulation of apoptotic pathways. shRNA-mediated interference may have potential therapeutic utility in human breast cancer.