Inhibition of Heat-shock Protein 27 Reduces 5-Fluorouracil-acquired Resistance in Human Colon Cancer Cells.

BACKGROUND/AIM: In previous work we showed that expression of heat-shock protein 27 (HSP27; encoded by HSPB1) was associated with inherent resistance to 5-fluorouracil (5-FU). However, the relationship between HSP27 and acquired resistance remains unknown. MATERIALS AND METHODS: We generated an acquired resistance model (WiDr-R) of a colon cancer cell line by exposing WiDr cells to 5-FU. Cell viability assays under treatment with 5-FU, as well as down-regulation of HSP27 using small interfering HSP27 RNA, were performed. HSP27 mRNA and protein expression was analyzed using real-time polymerase chain reaction and western blotting. RESULTS: 5-FU-acquired resistance induced overexpression of HSP27 mRNA and protein levels in WiDr-R cells. Furthermore, siRNA knockdown of HSP27 in WiDr-R cells reduced 5-FU-acquired resistance. CONCLUSION: These findings demonstrate that HSP27 is associated with 5-FU resistance in human colon cancer cell cells and suggest that HSP27 regulation represents a novel approach to overcoming chemoresistance in colorectal cancer.

Small-Molecule HSP27 Inhibitor Abolishes Androgen Receptors in Glioblastoma.

Androgen receptor (AR) contributes to the progression of glioblastoma (GBM), and antiandrogen agents have the potential to be used for the treatment of GBM. However, AR mutation commonly happens in GBM, which makes the antiandrogen agents less effective. Heat shock 27 kDa protein (HSP27) is a well-documented chaperone protein to stabilize ARs. Inhibition of HSP27 results in AR degradation regardless of the mutation status of ARs, which makes HSP27 a good target to abolish ARs in GBM. Compound I is a HSP27 inhibitor that significantly induces AR degradation in GBM cells via the proteasomal pathway, and it selectively inhibits AR-overexpressed GBM cell growth with IC50 values around 5 nM. The compound also significantly inhibits in vivo GBM xenograft at 20 mg/kg and does not cause toxicity to mice up to 80 mg/kg. These results suggest that targeting HSP27 to induce AR degradation in GBM is a promising and novel treatment.

Self-Assembling Supramolecular Dendrimers for Biomedical Applications: Lessons Learned from Poly(amidoamine) Dendrimers.

Dendrimers, notable for their well-defined radial structures with numerous terminal functionalities, hold great promise for biomedical applications such as drug delivery, diagnostics, and therapeutics. However, their translation into clinical use has been greatly impeded by their challenging stepwise synthesis and difficult purification.To circumvent these obstacles, we have pioneered a self-assembly approach to constructing noncovalent supramolecular dendrimers using small amphiphilic dendrimer building units which can be easily synthesized and purified. By virtue of their amphipathic nature, the small amphiphilic dendrimers are able to self-assemble and generate large supramolecular dendrimers via noncovalent weak interactions such as van der Waals forces, H bonds, and electrostatic interactions. The so-created noncovalent dendrimers can mimic covalent dendrimers not only in terms of the radial structural feature emanating from a central core but also in their capacity to deliver drugs and imaging agents for biomedical applications. The noncovalent supramolecular dendrimers can be easily synthesized and modulated with regard to size, shape, and properties by varying the nature of the hydrophobic and hydrophilic entities as well as the dendrimer generation and terminal functionalities, ensuring their adaptability to specific applications. In particular, the dendritic structure of the amphiphilic building units permits the creation of large void spaces within the formed supramolecular dendrimers for the physical encapsulation of drugs, while the large number of surface functionalities can be exploited for both physical and chemical conjugation of pharmaceutic agents for drug delivery.Poly(amidoamine) (PAMAM) dendrimers are the most intensively studied for biomedical applications by virtue of their excellent biocompatibility imparted by their peptide-mimicking amide backbones and numerous interior and terminal amine functionalities. We present a short overview of our self-assembly strategy for constructing supramolecular PAMAM dendrimers for biomedical applications. Specifically, we start with the introduction of dendrimers and their synthesis, focusing on the innovative self-assembly synthesis of supramolecular dendrimers. We then detail the representative examples of the noncovalent supramolecular PAMAM dendrimers established in our group for the delivery of anticancer drugs, nucleic acid therapeutics, and imaging agents, either within the dendrimer interior or at the dendrimer terminals on the surface. Some of the supramolecular dendrimer nanosystems exhibit outstanding performance, excelling the corresponding clinical anticancer therapeutics and imaging agents. This self-assembly approach to creating supramolecular dendrimers is completely novel in concept yet easy to implement in practice, offering a fresh perspective for exploiting the advantageous features of dendrimers in biomedical applications.

Heat shock protein 27 as a neuroprotective biomarker and a suitable target for stem cell therapy and pharmacotherapy in ischemic stroke.

Ischemic stroke is a major common cause of death and long-term disability worldwide. Several pathophysiological events including excitotoxicity, oxidative/nitrative stress, inflammation, and apoptosis are involved in ischemic injuries. Recently, the molecular mechanisms involved in cerebral ischemia through a focus on a member of small heat shock proteins family, Hsp27, has been developed. Notably, following exposure to ischemia, Hsp27 expression in the brain could be increased rather than the normal condition and it may play an important role in neuroprotection after ischemic stroke. The neuroprotection effects of Hsp27 may arise from its anti-oxidant, anti-inflammatory, anti-apoptotic, and chaperonic properties. Moreover, some therapeutic strategies such as stem cell therapy and pharmacotherapy have been developed with Hsp27 targeting. In this review, we describe the function and structure of Hsp27 and its possible role in neuroprotection after ischemic stroke. Finally, we present current studies in stroke therapy, which focused on Hsp27 targeting.

Schisandrin B ameliorates high-glucose-induced vascular endothelial cells injury by regulating the Noxa/Hsp27/NF-κB signaling pathway.

BACKGROUND: To address the molecular mechanism of the anti-inflammation effects of schisandrin B (Sch B) in atherosclerosis, we examined injured HMEC-1, HBMEC, and HUVEC-12 cells induced by high glucose (HG). METHODS: Western blot was performed to detect the levels of the proteins Hsp27, Noxa, TLR5, p-IκBα, and p-p65 in HG-induced cells, while ELISA was used to analyze the inflammatory cytokines TNF-α, IL-6, MCP-1, and IL-1ß in cells with Hsp27 or Noxa stable expression. RESULTS: Overexpression of Hsp27 upregulated the inflammatory cytokines and the release of IκBα, promoted transportation of p65 into the nucleus, and lastly, affected the inflammation process, while Sch B counteracted the upregulation. In addition, the effect of Noxa overexpression, which is different from Hsp27 overexpression, was consistent with that of Sch B treatment. CONCLUSIONS: Sch B may inhibit the inflammatory cascade and alleviate the injury to HMEC-1, HBMEC, and HUEVC-12 cells caused by HG by regulating the Noxa/Hsp27/NF-κB signaling pathway.

Hsp-27 and NF-κB pathway is associated with AR/AR-V7 expression in prostate cancer cells.

In the present study, NF-κB inhibitor BAY 11-7082 and/or Hsp-27 inhibitor KRIBB-3 agents were used to investigate the molecular mechanisms mediating androgen receptor expression on prostate cancer cell lines. The decrease observed in androgen receptor and p65 expressions, particularly at 48 h, in parallel with the decrease in the phosphorylation of the p-IKK α/ß and p-Hsp-27 proteins in the LNCaP cells, indicated that androgen receptor inactivation occurred after the inhibition of the NF-κB and Hsp-27. In 22Rv1 cells, androgen receptor variant-7 was also observed to be decreased in the combined dose of 48 h. The association of this decrease with the decrease in androgen receptor and p65 expressions is a supportive result for the role of NF-κB signaling in the formation of androgen receptor variant. In androgen receptor variant-7 siRNA treatment in 22Rv1 cell lines, decrease of expression of androgen receptor variant-7 as well as decrease of expression of androgen receptor and p65 were observed. The decrease statistically significant in androgen receptor and p65 expressions was even greater when siRNA treatment was followed with low dose and time (6 h) combined treatment after transfection. We also showed that increased Noxa and decreased Bcl-2 protein level, indicated that apoptotic induction after this combination. In conclusion, inhibition of NF-κB and Hsp-27 is also important, along with therapies for androgen receptor variant-7 inhibition.

A Dual Targeting Dendrimer-Mediated siRNA Delivery System for Effective Gene Silencing in Cancer Therapy.

Small interfering RNA (siRNA) is emerging as a novel therapeutic for treating various diseases, provided a safe and efficient delivery is available. In particular, specific delivery to target cells is critical for achieving high therapeutic efficacy while reducing toxicity. Amphiphilic dendrimers are emerging as novel promising carriers for siRNA delivery by virtue of the combined multivalent cooperativity of dendrimers with the self-assembling property of lipid vectors. Here, we report a ballistic approach for targeted siRNA delivery to cancer cells using an amphiphilic dendrimer equipped with a dual targeting peptide bearing an RGDK warhead. According to the molecular design, the amphiphilic dendrimer was expected to deliver siRNA effectively, while the aim of the targeting peptide was to home in on tumors via interaction of its warhead with integrin and the neuropilin-1 receptor on cancer cells. Coating the positively charged siRNA/dendrimer delivery complex with the negatively charged segment of the targeting peptide via electrostatic interactions led to small and stable nanoparticles which were able to protect siRNA from degradation while maintaining the accessibility of RGDK for targeting cancer cells and preserving the ability of the siRNA to escape from endosomes. The targeted system had enhanced siRNA delivery, stronger gene silencing, and more potent anticancer activity compared to nontargeted or covalent dendrimer-based systems. In addition, neither acute toxicity nor induced inflammation was observed. Consequently, this delivery system constitutes a promising nonviral vector for targeted delivery and can be further developed to provide RNAi-based personalized medicine against cancer. Our study also gives new perspectives on the use of nanotechnology based on self-assembling dendrimers in various biomedical applications.

Cytoprotective effect of eupatilin against indomethacin-induced damage in feline esophageal epithelial cells: relevance of HSP27 and HSP70.

Indomethacin is a non-steroidal anti-inflammatory drug with clearly known side effects on the gastrointestinal tract. The purpose of the present study was to investigate whether eupatilin inhibit cell injury induced by indomethacin in cultured feline esophageal epithelial cells (EECs). EECs were used to investigate the ability of eupatilin to induce the expression of heat shock proteins (HSP27 and HSP70) and analyze its cytoprotective effect against indomethacin-induced damage. The treatment of EECs with indomethacin for 8 h decreased cell viability. Western blot analysis showed that the levels of HSPs gradually decreased in cells treated with indomethacin, while eupatilin treatment increased the levels of HSPs. When treated with both indomethacin and eupatilin, the levels of HSPs increased rapidly, and were maintained at 130-140%. In addition, treatment with the specific inhibitors of PTK, PKC, PLC, p38 MAPK, JNKs, and PI3K attenuated the eupatilin-induced expression of HSPs. Pretreatment of EECs with the inhibitors of protein synthesis, actinomycin D or cycloheximide, attenuated the cytoprotective effect of eupatilin on indomethacin-induced cell damage. Reactive oxygen species production was upregulated by indomethacin, but downregulated by eupatilin. Taken together, it was suggested that HSPs were partly responsible for the eupatilin-mediated cytoprotective activity against the indomethacin-induced damage in EECs.

Chemotherapy Sensitizes Therapy-Resistant Cells to Mild Hyperthermia by Suppressing Heat Shock Protein 27 Expression in Triple-Negative Breast Cancer.

Purpose: Triple-negative breast cancer (TNBC) is a clinically aggressive disease with poor prognosis. Conventional chemotherapeutics are generally able to shrink the tumor mass, but often fail to completely eradicate cancer stem-like cells (CSCs) that are responsible for high risk of relapse and frequent metastases. In this study, we examined thermal sensibility of CSCs, developed an approach that enabled concurrent elimination of both the bulk of cancer cells and CSCs, and investigated the underlying mechanism.Experimental Design: We designed a platform consisting of gold nanoparticle-coated porous silicon microparticle (AuPSM) that was also loaded with docetaxel micelles (mDTXs) to enable concurrent killing of the bulk of cancer cells by released mDTX and CSCs by mild hyperthermia upon stimulation of AuPSM with near infrared. In addition, we examined the role of heat shock proteins in sensitizing CSC killing. Finally, we applied mDTX-loaded AuPSM to treat mice with SUM159 and 4T1 orthotopic tumors and evaluated tumor growth and tumor metastasis.Results: MDA-MB-231 and SUM159 TNBC cells treated with mDTX-loaded AuPSM and mild hyperthermia displayed significantly reduced efficiencies in mammosphere formation than those treated with mDTX alone or mild hyperthermia alone. Combination treatment also completely inhibited SUM159 orthotopic tumor growth and 4T1 tumor metastasis. Mechanistically, DTX treatment suppressed expression of heat shock protein 27 in cancer cells including the CSCs, rendering cells sensitive to mild hyperthermia.Conclusions: Our results indicate that chemotherapy sensitizes CSC to mild hyperthermia. We have developed an effective therapeutic approach to eliminate therapy-resistant cells in TNBC. Clin Cancer Res; 24(19); 4900-12. ©2018 AACR.

Heat shock protein-27 and sex-selective regulation of muscarinic and proteinase-activated receptor 2-mediated vasodilatation: differential sensitivity to endothelial NOS inhibition.

BACKGROUND AND PURPOSE: Previously, we demonstrated that exogenous heat shock protein 27 (HSP27/gene, HSPB1) treatment of human endothelial progenitor cells (EPCs) increases the synthesis and secretion of VEGF, improves EPC-migration/re-endothelialization and decreases neo-intima formation, suggesting a role for HSPB1 in regulating EPC function. We hypothesized that HSPB1 also affects mature endothelial cells (ECs) to alter EC-mediated vasoreactivity in vivo. Our work focused on endothelial NOS (eNOS)/NO-dependent relaxation induced by ACh and the coagulation pathway-activated receptor, proteinase-activated receptor 2 (PAR2). EXPERIMENTAL APPROACH: Aorta rings from male and female wild-type, HSPB1-null and HSPB1 overexpressing (HSPB1o/e) mice were contracted with phenylephrine, and NOS-dependent relaxation responses to ACh and PAR2 agonist, 2-furoyl-LIGRLO-NH2 , were measured without and with L-NAME and ODQ, either alone or in combination to block NO synthesis/action. Tissues from female HSPB1-null mice were treated in vitro with recombinant HSP27 and then used for bioassay as above. Furthermore, oestrogen-specific effects were evaluated using a bioassay of aorta isolated from ovariectomized mice. KEY RESULTS: Relative to males, HSPB1-null female mice exhibited an increased L-NAME-resistant relaxation induced by activation of either PAR2 or muscarinic ACh receptors that was blocked in the concurrent presence of both L-NAME and ODQ. mRNAs (qPCR) for eNOS and ODQ-sensitive guanylyl-cyclase were increased in females versus males. Treatment of isolated aorta tissue with HSPB1 improved tissue responsiveness in the presence of L-NAME. Ovariectomy did not affect NO sensitivity, supporting an oestrogen-independent role for HSPB1. CONCLUSIONS AND IMPLICATIONS: HSPB1 can regulate intact vascular endothelial function to affect NO-mediated vascular relaxation, especially in females.

HSP27 inhibitor attenuates radiation-induced pulmonary inflammation.

Radiation therapy has been used to treat over 70% of thoracic cancer; however, the method usually causes radiation pneumonitis. In the current study, we investigated the radioprotective effects of HSP27 inhibitor (J2) on radiation-induced lung inflammation in comparison to amifostine. In gross and histological findings, J2 treatment significantly inhibited immune cell infiltration in lung tissue, revealing anti-inflammatory potential of J2. Normal lung volume, evaluated by micro-CT analysis, in J2-treated mice was higher compared to that in irradiated mice. J2-treated mice reversed radiation-induced respiratory distress. However, amifostine did not show significant radioprotective effects in comparison to that of J2. In HSP27 transgenic mice, we observed increased immune cells recruitment and decreased volume of normal lung compared to wild type mice. Increased ROS production and oxidative stress after IR were down-regulated by J2 treatment, demonstrating antioxidant property of J2. The entire data of this study collectively showed that J2 may be an effective therapeutic agent for radiation-induced lung injury.

Heat shock protein 27 knockdown using nucleotide­based therapies enhances sensitivity to 5-FU chemotherapy in SW480 human colon cancer cells.

Heat shock protein 27 (Hsp27) is a chaperone protein of low molecular weight that is produced in response to various stresses and has a cytoprotective function. In the present study we found that there is a strong correlation between sensitivity to 5-fluorouracil (5-FU) and the expression of Hsp27 in colorectal cancer. Apatorsen is an antisense oligonucleotide that targets Hsp27 and has various antitumor effects in some types of cancer, such as bladder and prostate. Although several clinical studies are currently studying apatorsen in many malignancies, to date no promising results have been reported for colorectal cancer. In the present study, we examined the impact of Hsp27 downregulation (via apatorsen) on 5-FU sensitivity in colon cancer both in vitro and in vivo. In vitro, apatorsen significantly decreased the levels of Hsp27 in a dose-dependent manner in human colon cancer SW480 cells. A cell proliferation assay revealed that although apatorsen did not inhibit tumor growth, it resulted in greater 5-FU sensitivity in comparison with treatment with OGX-411 (control). In vivo, intraperitoneal injection of apatorsen decreased the levels of Hsp27 in subcutaneous tumors in a xenograft mouse model using SW480 cells and enhanced 5-FU sensitivity, compared to controls. Although further research is warranted, the present study confirmed that concurrent treatment with Hsp27 knockdown using apatorsen and 5-FU could be a promising therapy for colon cancer.

A randomized phase 2 study of a HSP27 targeting antisense, apatorsen with prednisone versus prednisone alone, in patients with metastatic castration resistant prostate cancer.

Purpose Heat shock protein 27 (Hsp27) is implicated in prostate cancer progression. Apatorsen is a second generation phosphorothioate antisense inhibitor of Hsp27 expression. We evaluated apatorsen in patients with metastatic castration resistant prostate cancer (mCRPC). Experimental design Eligible patients were randomized 1:1 to receive intravenous apatorsen (3 loading doses of 600 mg within 5-9 days followed by weekly doses of 1000 mg) with oral prednisone 5 mg twice daily or prednisone alone. The primary endpoint was disease progression at 12 weeks. Crossover from prednisone alone was allowed after radiographic progression. Results 74 patients received apatorsen + prednisone (n = 36) or prednisone alone (n = 38). Twenty-five patients crossed-over to receive apatorsen + prednisone. Apatorsen treated patients received a median of 19 infusions. 50% of apatorsen + prednisone patients (95% CI: 32.9%, 67.1%) compared with 42% of prednisone patients (95% CI: 26.3%, 59.2%) did not have disease progression at week 12 (P = 0.33). A PSA decline of ≥50% was observed in 47% of apatorsen + prednisone and 24% of prednisone patients (P = 0.04), with a median duration of response of 24.1 weeks (95% CI: 12.0, 52) and 14.0 weeks (95% CI: 4.0, 44.4), respectively. A PSA decline of ≥50% was observed in 5 patients (20%) that received cross-over apatorsen. Infusion reactions were the most commonly reported adverse event occurring in 77% of apatorsen-treated patients. Conclusions Apatorsen + prednisone did not change the proportion of CRPC patients without disease progression at 12 weeks compared to prednisone but was associated with significant PSA declines. Further evaluation of Hsp27 targeting in prostate cancer is warranted.

LPS ameliorates renal ischemia/reperfusion injury via Hsp27 up-regulation.

PURPOSE: We have recently reported lipopolysaccharide (LPS) pretreatment attenuated renal ischemia/reperfusion injury (IRI), but the exact mechanism remains to be well elucidated. It was reported that heat shock protein (Hsp) 27 was up-regulated after administration of LPS, but whether a direct link existed between Hsp27 up-regulation and LPS-induced protection against renal IRI is still unknown. METHODS: Mice were exposed to IRI or sham procedure, with pretreatment of LPS or not. Quercetin, an inhibitor of Hsp27 synthesis, was used, and an RNA interference with adenovirus vector using short hairpin RNA targeting Hsp27 was developed for inhibition of Hsp27 in mice. In addition, mice trans-infected with adenovirus vector encoding Hsp27 were used to testify the role of Hsp27 overexpression in LPS-induced renoprotection. Renal function, histological damage, inflammatory reaction, oxidative stress and apoptosis indices were measured. Western blot analysis was used to detect expression of Hsp27. RESULTS: We found LPS pretreatment stimulated renal up-regulation of Hsp27 and reduced renal IRI proven by less renal dysfunction, histological damage, inflammatory reaction, oxidative stress and apoptosis. It was observed that inhibition of Hsp27 synthesis by Quercetin abolished LPS-induced renoprotective effects. After renal knockdown of Hsp27, LPS-induced tolerance against renal IRI was largely removed. Mice with Hsp27 overexpression showed significantly improved renal function after IRI and LPS combined with Hsp27 overexpression had a synergistic effect on protection against renal IRI. CONCLUSION: Administration of LPS produces protective effects against renal IRI via Hsp27 up-regulation. Preconditional Hsp27 up-regulation might have a great potential for the treatment of renal IRI via ameliorating apoptosis.

From malaria to cancer: Computational drug repositioning of amodiaquine using PLIP interaction patterns.

Drug repositioning identifies new indications for known drugs. Here we report repositioning of the malaria drug amodiaquine as a potential anti-cancer agent. While most repositioning efforts emerge through serendipity, we have devised a computational approach, which exploits interaction patterns shared between compounds. As a test case, we took the anti-viral drug brivudine (BVDU), which also has anti-cancer activity, and defined ten interaction patterns using our tool PLIP. These patterns characterise BVDU's interaction with its target s. Using PLIP we performed an in silico screen of all structural data currently available and identified the FDA approved malaria drug amodiaquine as a promising repositioning candidate. We validated our prediction by showing that amodiaquine suppresses chemoresistance in a multiple myeloma cancer cell line by inhibiting the chaperone function of the cancer target Hsp27. This work proves that PLIP interaction patterns are viable tools for computational repositioning and can provide search query information from a given drug and its target to identify structurally unrelated candidates, including drugs approved by the FDA, with a known safety and pharmacology profile. This approach has the potential to reduce costs and risks in drug development by predicting novel indications for known drugs and drug candidates.

Borealis-1: a randomized, first-line, placebo-controlled, phase II study evaluating apatorsen and chemotherapy for patients with advanced urothelial cancer.

BACKGROUND: Five-year survival of patients with inoperable, advanced urothelial carcinoma treated with the first-line chemotherapy is 5%-15%. We assessed whether the Hsp27 inhibitor apatorsen combined with gemcitabine plus cisplatin (GC) could improve overall survival (OS) in these patients. PATIENTS AND METHODS: This placebo-controlled, double-blind, phase II trial randomized 183 untreated urothelial carcinoma patients (North America and Europe) to receive GC plus either placebo (N = 62), 600 mg apatorsen (N = 60), or 1000 mg apatorsen (N = 61). In the experimental arm, treatment included loading doses of apatorsen followed by up to six cycles of apatorsen plus GC. Patients receiving at least four cycles could continue apatorsen monotherapy as maintenance until progression or unacceptable toxicity. The primary end point was OS. RESULTS: OS was not significantly improved in the single or combined 600- or 1000-mg apatorsen arms versus placebo [hazard ratio (HR), 0.86 and 0.90, respectively]. Exploratory study of specific statistical modeling showed a trend for improved survival in patients with baseline poor prognostic features treated with 600 mg apatorsen compared with placebo (HR = 0.72). Landmark analysis of serum Hsp27 (sHsp27) levels showed a trend toward survival benefit for poor-prognosis patients in 600- and 1000-mg apatorsen arms who achieved lower area under the curve sHsp27 levels, compared with the placebo arm (HR = 0.45 and 0.62, respectively). Higher baseline circulating tumor cells (≥5 cells/7.5 ml) was observed in patients with poor prognosis in correlation with poor survival. Treatment-emergent adverse events were manageable and more common in both apatorsen-treatment arms. CONCLUSIONS: Even though apatorsen combined with standard chemotherapy did not demonstrate a survival benefit in the overall study population, patients with poor prognostic features might benefit from this combination. Serum Hsp27 levels may act as a biomarker to predict treatment outcome. Further exploration of apatorsen in poor-risk patients is warranted.

A Randomized, Double-Blinded, Phase II Trial of Gemcitabine and Nab-Paclitaxel Plus Apatorsen or Placebo in Patients with Metastatic Pancreatic Cancer: The RAINIER Trial.

LESSONS LEARNED: The addition of the heat shock protein 27 (Hsp27)-targeting antisense oligonucleotide, apatorsen, to a standard first-line chemotherapy regimen did not result in improved survival in unselected patients with metastatic pancreatic cancer.Findings from this trial hint at the possible prognostic and predictive value of serum Hsp27 that may warrant further investigation. BACKGROUND: This randomized, double-blinded, phase II trial evaluated the efficacy of gemcitabine/nab-paclitaxel plus either apatorsen, an antisense oligonucleotide targeting heat shock protein 27 (Hsp27) mRNA, or placebo in patients with metastatic pancreatic cancer. METHODS: Patients were randomized 1:1 to Arm A (gemcitabine/nab-paclitaxel plus apatorsen) or Arm B (gemcitabine/nab-paclitaxel plus placebo). Treatment was administered in 28-day cycles, with restaging every 2 cycles, until progression or intolerable toxicity. Serum Hsp27 levels were analyzed at baseline and on treatment. The primary endpoint was overall survival (OS). RESULTS: One hundred thirty-two patients were enrolled, 66 per arm. Cytopenias and fatigue were the most frequent grade 3/4 treatment-related adverse events for both arms. Median progression-free survival (PFS) and OS were 2.7 and 5.3 months, respectively, for arm A, and 3.8 and 6.9 months, respectively, for arm B. Objective response rate was 18% for both arms. Patients with high serum level of Hsp27 represented a poor-prognosis subgroup who may have derived modest benefit from addition of apatorsen. CONCLUSION: Addition of apatorsen to chemotherapy does not improve outcomes in unselected patients with metastatic pancreatic cancer in the first-line setting, although a trend toward prolonged PFS and OS in patients with high baseline serum Hsp27 suggests this therapy may warrant further evaluation in this subgroup.

Synthesis and biological effect of chrom-4-one derivatives as functional inhibitors of heat shock protein 27.

Heat Shock Protein 27 (HSP27) is a member of small heat shock proteins with a highly-conserved α-crystalline domain. It inhibits aggregation of damaged proteins through a complex structural systems of phosphorylation-dependent oligomerization and self-assembly. It has been demonstrated that HSP27 is involved in a variety of pathophysiological pathways with negative or positive protective activities. In this study, we synthesized six chromone analogs possessing thiiran-2-ylmethoxy or oxyran-2-ylmethoxy substituents and evaluated their biological activities against HSP27 protein. Compounds YK598-2, J4 and J2 induced significant abnormal HSP27 dimer formation in NCI-H460, a human lung cancer cell line. In synergistic anticancer activity test, the compounds effectively producing abnormal HSP27 cross-linking remarkably enhanced the antiproliferative activity of 17-AAG, a HSP90 inhibitor. Target specificity test using the HSP27-silenced cells (shHSP27) showed that compounds YK598-2, J4, and J2 significantly lost their cross-linking activity only under conditions when HSP27 was deprived of. In the evaluation of cancer cell sensitization with cisplatin, cisplatin-induced lung cancer cell growth inhibition was sensitized with statistical significance by J4 and J2 as compared to compound alone treatment. These results suggest that abnormal HSP27 dimerization can be an efficient control point for cancer cell proliferation and chromone compounds might have potential as anticancer agents that modulate abnormal HSP27 dimerization.

Anti-proliferation and anti-metastasis effect of barbaloin in non-small cell lung cancer via inactivating p38MAPK/Cdc25B/Hsp27 pathway.

Non-small cell lung carcinoma (NSCLC) is the most common lung cancer with high morbidity and mortality. The traditional treatment for NSCLC is particularly liable to relapse with many side-effects. Barbaloin is a natural compound with anticancer efficacy. The present study aimed to investigate the anticancer potential of barbaloin in NSCLC. The results displayed that barbaloin inhibited the viability of A549 cells by decreasing cell growth and the expression level of Ki-67 and proliferating cell nuclear antigen (PCNA), especially at high concentrations (50 and 100 µM). Besides, barbaloin increased the apoptosis rate of A549 cells and induced an accumulation of G2/M phase. Increased expression of apoptosis-related proteins (caspase-3, -8 and -9) and the changed levels of cell cycle checkpoint proteins (p27, p53 and cyclin A) further convinced of the anti-viability effect of barbaloin in A549 cells. On the other hand, barbaloin significantly suppressed the invasion and migration of A549 cells, and restrained the expression of tumor metastasis-related proteins. We further explored the activation of pro-survival or pro-metastasis signaling pathways, including AKT, nuclear factor kappa B (NF-κB), mitogen-actived protein kinase (MAPK) and ß-catenin. The results revealed that barbaloin inactivated the p38MAPK/Cdc25B/Hsp27 pathway by inhibiting p38 nucleus translocation, while no significant influence was observed among other pathways. Finally, barbaloin restrained the growth and hepatic metastases of A549 cells in vivo. Taken together, our research indicated that barbaloin inhibited the proliferation and metastasis of NSCLC cells in vivo and in vitro. This may provide safer and more effective aspects for the treatment of NSCLC.

Heterogeneous nuclear ribonucleoprotein K inhibits heat shock-induced transcriptional activity of heat shock factor 1.

When cells are exposed to heat shock and various other stresses, heat shock factor 1 (HSF1) is activated, and the heat shock response (HSR) is elicited. To better understand the molecular regulation of the HSR, we used 2D-PAGE-based proteome analysis to screen for heat shock-induced post-translationally modified cellular proteins. Our analysis revealed that two protein spots typically present on 2D-PAGE gels and containing heterogeneous nuclear ribonucleoprotein K (hnRNP K) with trioxidized Cys132 disappeared after the heat shock treatment and reappeared during recovery, but the total amount of hnRNP K protein remained unchanged. We next tested whether hnRNP K plays a role in HSR by regulating HSF1 and found that hnRNP K inhibits HSF1 activity, resulting in reduced expression of hsp70 and hsp27 mRNAs. hnRNP K also reduced binding affinity of HSF1 to the heat shock element by directly interacting with HSF1 but did not affect HSF1 phosphorylation-dependent activation or nuclear localization. hnRNP K lost its ability to induce these effects when its Cys132 was substituted with Ser, Asp, or Glu. These findings suggest that hnRNP K inhibits transcriptional activity of HSF1 by inhibiting its binding to heat shock element and that the oxidation status of Cys132 in hnRNP K is critical for this inhibition.