Hsp27 Inhibition with OGX-427 Sensitizes Non-Small Cell Lung Cancer Cells to Erlotinib and Chemotherapy

Targeting pediatric solid tumors in the new era of RNA therapeutics

Despite substantial progress in pediatric cancer treatment, poor prognosis remained for patients with recurrent or metastatic disease, given the limitations of approved targeted treatments and immunotherapies. RNA therapeutics offer significant potential for addressing a broad spectrum of diseases, including cancer. Advances in manufacturing and delivery systems are paving the way for the rapid development of therapeutic RNAs for clinical applications. This review summarizes therapeutic RNA classifications and the mechanisms of action, highlighting their potential in manipulating major cancer-related pathways and biological effects. We also focus on the pre-clinical investigation of RNA molecules with efficient delivery systems for their therapeutic potential targeting pediatric solid tumors.

Heat Shock Proteins, a Double-Edged Sword: Significance in Cancer Progression, Chemotherapy Resistance and Novel Therapeutic Perspectives

Heat shock proteins (Hsps) are involved in one of the adaptive mechanisms protecting cells against environmental and metabolic stress. Moreover, the large role of these proteins in the carcinogenesis process, as well as in chemoresistance, was noticed. This review aims to draw attention to the possibilities of using Hsps in developing new cancer therapy methods, as well as to indicate directions for future research on this topic. In order to discuss this matter, a thorough review of the latest scientific literature was carried out, taking into account the importance of selected proteins from the Hsp family, including Hsp27, Hsp40, Hsp60, Hsp70, Hsp90 and Hsp110. One of the more characteristic features of all Hsps is that they play a multifaceted role in cancer progression, which makes them an obvious target for modern anticancer therapy. Some researchers emphasize the importance of directly inhibiting the action of these proteins. In turn, others point to their possible use in the design of cancer vaccines, which would work by inducing an immune response in various types of cancer. Due to these possibilities, it is believed that the use of Hsps may contribute to the progress of oncoimmunology, and thus help in the development of modern anticancer therapies, which would be characterized by higher effectiveness and lower toxicity to the patients.

The heat shock protein Hsp27 controls mitochondrial function by modulating ceramide generation

Sphingolipids have key functions in membrane structure and cellular signaling. Ceramide is the central molecule of the sphingolipid metabolism and is generated by ceramide synthases (CerS) in the de novo pathway. Despite their critical function, mechanisms regulating CerS remain largely unknown. Using an unbiased proteomics approach, we find that the small heat shock protein 27 (Hsp27) interacts specifically with CerS1 but not other CerS. Functionally, our data show that Hsp27 acts as an endogenous inhibitor of CerS1. Wild-type Hsp27, but not a mutant deficient in CerS1 binding, inhibits CerS1 activity. Additionally, silencing of Hsp27 enhances CerS1-generated ceramide accumulation in cells. Moreover, phosphorylation of Hsp27 modulates Hsp27-CerS1 interaction and CerS1 activity in acute stress-response conditions. Biologically, we show that Hsp27 knockdown impedes mitochondrial function and induces lethal mitophagy in a CerS1-dependent manner. Overall, we identify an important mode of CerS1 regulation and CerS1-mediated mitophagy through protein-protein interaction with Hsp27.

Budding uninhibited by benzimidazoles-1 (BUB1) regulates EGFR signaling by reducing EGFR internalization

EGFR signaling initiates upon ligand binding which leads to activation and internalization of the receptor-ligand complex. Here, we evaluated if BUB1 impacted EGFR signaling by regulating EGFR receptor internalization and activation. BUB1 was ablated genomically (siRNA) or biochemically (2OH-BNPP1) in cells. EGF ligand was used to initiate EGFR signaling while disuccinimidyl suberate (DSS) was used for cross linking cellular proteins. EGFR signaling was measured by western immunoblotting and receptor internalization was evaluated by fluorescent microscopy (pEGFR (pY1068) colocalization with early endosome marker EEA1). siRNA mediated BUB1 depletion led to an overall increase in total EGFR levels and more phospho-EGFR (Y845, Y1092, and Y1173) dimers while the amount of total EGFR (non-phospho) dimers remained unchanged. BUB1 inhibitor (BUB1i) decreased EGF mediated EGFR signaling including pEGFR Y845, pAKT S473 and pERK1/2 in a time dependent manner. Additionally, BUB1i also reduced EGF mediated pEGFR (Y845) dimers (asymmetric dimers) without affecting total EGFR dimers (symmetric dimers) indicating that dimerization of inactive EGFR is not affected by BUB1. Furthermore, BUB1i blocked EGF mediated EGFR degradation (increase in EGFR half-life) without impacting half-lives of HER2 or c-MET. BUB1i also reduced co-localization of pEGFR with EEA1 positive endosomes suggesting that BUB1 might modulate EGFR endocytosis. Our data provide evidence that BUB1 protein and its kinase activity may regulate EGFR activation, endocytosis, degradation, and downstream signaling without affecting other members of the receptor tyrosine kinase family.

Untangling the complexity of heat shock protein 27 in cancer and metastasis

Heat shock protein 27 is a type of molecular chaperone whose expression gets up-regulated due to reaction towards different stressful triggers including anticancer treatments. It is known to be a major player of resistance development in cancer cells, whereby cells are sheltered against the therapeutics that normally activate apoptosis. Heat shock protein 27 (HSP27) is one of the highly expressed proteins during various cellular insults and is a strong tumor survival factor. HSP27 influences various cellular pathways associated with cancer cell survival and growth such as apoptosis, autophagy, metastasis, angiogenesis, epithelial to mesenchymal transition, etc. HSP27 is molecular machinery which prevents the clumping of numerous substrates or client proteins which get mutated in cancer. It has been reported in several studies that targeting HSP27 is difficult because of its dynamic structure and absence of an ATP-binding site. Here, in this review, we have summarized different modulators of HSP27 and their mechanism of action as well. Effect of deregulated HSP27 in various cancer models, limitations of targeting HSP27, resistance against the conventional drugs generated due to the overexpression of HSP27, and measures to counteract this effect have also been discussed here in detail.

Inhibition of Heat Shock Factor 1 Signaling Decreases Hepatoblastoma Growth via Induction of Apoptosis

Although rare compared with adult liver cancers, hepatoblastoma (HB) is the most common pediatric liver malignancy, and its incidence is increasing. Currently, the treatment includes surgical resection with or without chemotherapy, and in severe cases, liver transplantation in children. The effort to develop more targeted, HB-specific therapies has been stymied by the lack of fundamental knowledge about HB biology. Heat shock factor 1 (HSF1), a transcription factor, is a canonical inducer of heat shock proteins, which act as chaperone proteins to prevent or undo protein misfolding. Recent work has shown a role for HSF1 in cancer beyond the canonical heat shock response. The current study found increased HSF1 signaling in HB versus normal liver. It showed that less differentiated, more embryonic tumors had higher levels of HSF1 than more differentiated, more fetal-appearing tumors. Most strikingly, HSF1 expression levels correlated with mortality. This study used a mouse model of HB to test the effect of inhibiting HSF1 early in tumor development on cancer growth. HSF1 inhibition resulted in fewer and smaller tumors, suggesting HSF1 is needed for aggressive tumor growth. Moreover, HSF1 inhibition also increased apoptosis in tumor foci. These data suggest that HSF1 may be a viable pharmacologic target for HB treatment.

DNA Damage Repair Proteins, HSP27, and Phosphorylated-HSP90α as Predictive/Prognostic Biomarkers of Platinum-based Cancer Chemotherapy: An Exploratory Study

Platinum analogs are commonly used for cancer treatment. There is increasing interest in finding biomarkers which could predict and overcome resistance, because to date there is no reliable predictive/prognostic marker for these compounds. Here we studied the immunohistochemical expression of proteins involved in DNA damage response and repair (γH2AX, 53BP1, ERCC1, MLH1, and MSH2) in primary tumor tissues from patients treated with platinum-based chemotherapy. Levels and localization of Heat Shock Protein (HSP)27 and phospho-(Thr5/7)-HSP90α (p-HSP90α) were also determined. The implications in clinical response, disease-free survival and overall survival were analyzed. High γH2AX and 53BP1 expressions were associated with poor clinical response. Nuclear p-HSP90α, as well as nuclear absence and low cytoplasmic expression of HSP27 correlated with good response. Patients with high γH2AX and high cytoplasmic HSP27 expressions had shorter overall survival and disease-free survival. MLH1, MSH2, or ERCC1 were not associated with clinical response or survival. We report the potential utility of p-HSP90α, HSP27, γH2AX, and 53BP1 as predictive/prognostic markers for platinum-based chemotherapy. We present the first study that evaluates the predictive and prognostic value of p-HSP90α in primary tumors. Our research opens new possibilities for clinical oncology and shows the usefulness of immunohistochemistry for predicting chemotherapy response and prognosis in cancer.

Heat Shock Proteins 27, 70, and 110: Expression and Prognostic Significance in Colorectal Cancer

Heat shock proteins (HSPs) are evolutionarily conserved chaperones occurring in virtually all living organisms playing a key role in the maintenance of cellular homeostasis. They are constitutively expressed to prevent and repair protein damage following various physiological and environmental stressors. HSPs are overexpressed in various types of cancers to provide cytoprotective function, and they have been described to influence prognosis and response to therapy. Moreover, they have been used as a tumor marker in blood serum biochemistry and they represent a potentially promising therapeutic target. To clarify prognostic significance of two canonical HSPs (27 and 70) and less known HSP110 (previously known as HSP105) in colorectal carcinoma (CRC), we retrospectively performed HSP immunohistochemistry on tissue microarrays from formalin-fixed paraffin-embedded tumor tissue from 297 patients with known follow-up. Survival analysis (univariate Kaplan-Meier analysis with the log-rank test and multivariate Cox regression) revealed significantly shorter overall survival (OS, mean 5.54 vs. 7.07, p = 0.033) and borderline insignificantly shorter cancer specific survival (CSS, mean 6.3 vs. 7.87 years, p = 0.066) in patients with HSP70+ tumors. In the case of HSP27+ tumors, there was an insignificantly shorter OS (mean 6.36 vs. 7.13 years, p = 0.2) and CSS (mean 7.17 vs. 7.95 years, p = 0.2). HSP110 showed no significant impact on survival. Using Pearson's chi-squared test, there was a significant association of HSP27 and HSP70 expression with advanced cancer stage. HSP27+ tumors were more frequently mismatch-repair proficient and vice versa (p = 0.014), and they occurred more often in female patients and vice versa (p = 0.015). There was an enrichment of left sided tumors with HSP110+ compared to the right sided (p = 0.022). In multivariate Cox regression adjusted on the UICC stage, grade and right/left side; both HSPs 27 and 70 were not independent survival predictors (p = 0.616 & p = 0.586). In multivariate analysis, only advanced UICC stage (p = 0) and right sided localization (p = 0.04) were independent predictors of worse CSS. In conclusion, from all three HSPs examined in our study, only HSP70 expression worsened CRC prognosis, although stage-dependent. The contribution of this article may be seen as a large survival analysis of HSPs 27 and 70 and the largest analysis of HSP110 described in CRC.

Small Hsps as Therapeutic Targets of Cystic Fibrosis Transmembrane Conductance Regulator Protein

Human small heat shock proteins are molecular chaperones that regulate fundamental cellular processes in normal and pathological cells. Here, we have reviewed the role played by HspB1, HspB4 and HspB5 in the context of Cystic Fibrosis (CF), a severe monogenic autosomal recessive disease linked to mutations in Cystic Fibrosis Transmembrane conductance Regulator protein (CFTR) some of which trigger its misfolding and rapid degradation, particularly the most frequent one, F508del-CFTR. While HspB1 and HspB4 favor the degradation of CFTR mutants, HspB5 and particularly one of its phosphorylated forms positively enhance the transport at the plasma membrane, stability and function of the CFTR mutant. Moreover, HspB5 molecules stimulate the cellular efficiency of currently used CF therapeutic molecules. Different strategies are suggested to modulate the level of expression or the activity of these small heat shock proteins in view of potential in vivo therapeutic approaches. We then conclude with other small heat shock proteins that should be tested or further studied to improve our knowledge of CFTR processing.

Recent Advances in Oligonucleotide Therapeutics in Oncology

Cancer is one of the leading causes of death worldwide. Conventional therapies, including surgery, radiation, and chemotherapy have achieved increased survival rates for many types of cancer over the past decades. However, cancer recurrence and/or metastasis to distant organs remain major challenges, resulting in a large, unmet clinical need. Oligonucleotide therapeutics, which include antisense oligonucleotides, small interfering RNAs, and aptamers, show promising clinical outcomes for disease indications such as Duchenne muscular dystrophy, familial amyloid neuropathies, and macular degeneration. While no approved oligonucleotide drug currently exists for any type of cancer, results obtained in preclinical studies and clinical trials are encouraging. Here, we provide an overview of recent developments in the field of oligonucleotide therapeutics in oncology, review current clinical trials, and discuss associated challenges.

Anti-NSCLC activity in vitro of Hsp90N inhibitor KW-2478 and complex crystal structure determination of Hsp90N-KW-2478

KW-2478 is a promising anti-cancer lead compound targeting to the molecular chaperone heat shock protein 90 ^N (Hsp90^N). Absence of complex crystal structure of Hsp90^N-KW-2478, however, hampered further structure optimization of KW-2478 and understanding on the molecular interaction mechanism. Herein, a high-resolution complex crystal structure of Hsp90^N-KW-2478 was determined by X-ray diffraction (XRD, resolution limit: 1.59 Å; PDB ID: 6LT8) and their molecular interaction was analyzed in detail, which suggested that KW-2478 perfectly bound in the N-terminal ATP-binding pocket of Hsp90 to disable its molecular chaperone function, therefore suppressed or killed cancer cells. The results from thermal shift assay (TSA, ΔTm, 18.82 ± 0.51 °C) and isothermal titration calorimetry (ITC, K_d, 7.30 ± 2.20 nM) suggested that there is an intense binding force and favorable thermodynamic changes during the process of KW-2478 binding with Hsp90^N. Additionally, KW-2478 exhibited favorable anti-NSCLC activity in vitro, as it inhibited cell proliferation (IC₅₀, 8.16 μM for A549; 14.29 μM for H1975) and migration, induced cell cycle arrest and promoted apoptosis. Thirty-six novel KW-2478 derivatives were designed, based on the complex crystal structure and molecular interaction analysis of Hsp90^N-KW-2478 complex. Among them, twenty-two derivatives exhibited increased binding force with Hsp90^N evaluated by molecular docking assay. The results would provide new guidance for anti-NSCLC new drug development based on the lead compound KW-2478.

AlphaB-crystallin and breast cancer: role and possible therapeutic strategies

AlphaB-crystallin (HSPB5) is one of the most prominent and well-studied members of the small heat shock protein (sHsp) family. To date, it is known that this protein modulates significant cellular processes and therefore, it is not surprising that its deregulation is involved in various human pathologies, including cancer diseases. Despite the pathogenic significance of HSPB5 in cancer and its regulatory mechanism related to aggressiveness is poorly understood, several reports describe the association of breast carcinoma progression with HSPB5, whose expression is also considered an independent predictor of breast cancer metastasis to the brain. Indeed, numerous authors indicate HSPB5 as a new valuable biomarker for clinicopathological parameters and poor prognosis in breast cancer. Considering the cytoprotective, anti-apoptotic, pro-angiogenic, and pro-metastatic properties of the sHsps, it is not surprising that they are considered as promising targets for anticancer treatment, even though, at present, a deeper understanding of their mode of action is needed to allow the development of precise therapeutic interventions. Data on the direct inhibition of different sHsps demonstrate promising results in cancer pathologies; however, specific strategies against HSPB5 have not been considered. This review highlights the most relevant findings on HSPB5 and its role in breast cancer, as well as the possible strategies in using HSPB5 inhibition for therapeutic purposes.

Adaptive response of resistant cancer cells to chemotherapy

Despite advances in cancer therapeutics and the integration of personalized medicine, the development of chemoresistance in many patients remains a significant contributing factor to cancer mortality. Upon treatment with chemotherapeutics, the disruption of homeostasis in cancer cells triggers the adaptive response which has emerged as a key resistance mechanism. In this review, we summarize the mechanistic studies investigating the three major components of the adaptive response, autophagy, endoplasmic reticulum (ER) stress signaling, and senescence, in response to cancer chemotherapy. We will discuss the development of potential cancer therapeutic strategies in the context of these adaptive resistance mechanisms, with the goal of stimulating research that may facilitate the development of effective cancer therapy.

Spinal heat shock protein 27 participates in PDGFRβ-mediated morphine tolerance through PI3K/Akt and p38 MAPK signalling pathways

BACKGROUND AND PURPOSE

The development of antinociceptive morphine tolerance is a clinically intractable problem. Earlier work has demonstrated the pivotal roles of PDGF and its receptor PDGFRβ in morphine tolerance. Here, we have investigated the role of spinal heat shock protein 27 (HSP27) in morphine tolerance and its relationship with PDGFRβ activation.

EXPERIMENTAL APPROACH

Rats were treated with morphine for 9 days, and its anti-nociceptive effect against thermal pain was evaluated by a tail-flick latency test. Western blot, real-time PCR, immunofluorescent staining, and various antagonists, agonists, and siRNA lentiviral vectors elucidated the roles of HSP27, PDGFRβ, and related signalling pathways in morphine tolerance.

KEY RESULTS

Chronic morphine administration increased expression and phosphorylation of HSP27 in the spinal cord. Down-regulating HSP27 attenuated the development of morphine tolerance. PDGFRβ antagonism inhibited HSP27 activation and attenuated and reversed morphine tolerance. PDGFRβ induction increased HSP27 expression and activation and partly decreased morphine analgesia. PDGFRβ inhibition reduced Akt and p38 MAPK activity in morphine tolerance. PI3K and p38 inhibitors reversed morphine tolerance and suppressed morphine-induced HSP27 phosphorylation.

CONCLUSION AND IMPLICATIONS

This study demonstrated for the first time that spinal HSP27 participates in PDGFRβ-mediated morphine tolerance via the PI3K/Akt and p38 MAPK signalling pathways. These findings suggest a potential clinical strategy for prolonging the antinociceptive effects of opioids during long-term pain control.

Small Heat Shock Proteins in Cancers: Functions and Therapeutic Potential for Cancer Therapy

Small heat shock proteins (sHSPs) are ubiquitous ATP-independent chaperones that play essential roles in response to cellular stresses and protein homeostasis. Investigations of sHSPs reveal that sHSPs are ubiquitously expressed in numerous types of tumors, and their expression is closely associated with cancer progression. sHSPs have been suggested to control a diverse range of cancer functions, including tumorigenesis, cell growth, apoptosis, metastasis, and chemoresistance, as well as regulation of cancer stem cell properties. Recent advances in the field indicate that some sHSPs have been validated as a powerful target in cancer therapy. In this review, we present and highlight current understanding, recent progress, and future challenges of sHSPs in cancer development and therapy.

Omega-3 Fatty Acid-Enriched Fish Oil and Selenium Combination Modulates Endoplasmic Reticulum Stress Response Elements and Reverses Acquired Gefitinib Resistance in HCC827 Lung Adenocarcinoma Cells

Non-small cell lung cancer (NSCLC)-carrying specific epidermal growth factor receptor (EGFR) mutations can be effectively treated by a tyrosine kinase inhibitor such as gefitinib. However, the inevitable development of acquired resistance leads to the eventual failure of therapy. In this study, we show the combination effect of omega-3 fatty acid-enriched fish oil (FO) and selenium (Se) on reversing the acquired gefitinib-resistance of HCC827 NSCLC cells. The gefitinib-resistant subline HCC827GR possesses lowered proapoptotic CHOP (CCAAT/enhancer-binding protein homologous protein) and elevated cytoprotective GRP78 (glucose regulated protein of a 78 kDa molecular weight) endoplasmic reticulum (ER) stress response elements, and it has elevated β-catenin and cyclooxygenase-2 (COX-2) levels. Combining FO and Se counteracts the above features of HCC827GR cells, accompanied by the suppression of their raised epithelial-to-mesenchymal transition (EMT) and cancer stem markers, such as vimentin, AXL, N-cadherin, CD133, CD44, and ABCG2. Accordingly, an FO and Se combination augments the gefitinib-mediated growth inhibition and apoptosis of HCC827GR cells, along with the enhanced activation of caspase -3, -9, and ER stress-related caspase-4. Intriguingly, gefitinib further increases the elevated ABCG2 and cancer stem-like side population in HCC827GR cells, which can also be diminished by the FO and Se combination. The results suggest the potential of combining FO and Se in relieving the acquired resistance of NSCLC patients to targeted therapy.

Heat shock proteins as biomarkers of lung cancer

Heat shock proteins are known to be associated with a wide variety of human cancers including lung cancer. Overexpression of these molecular chaperones is linked with tumor survival, metastasis and anticancer drug resistance. In recent years, heat shock proteins are gaining much importance in the field of cancer research owing to their potential to be key determinants of cell survival and apoptosis. Lung cancer is one of the most common cancers diagnosed worldwide and the association of heat shock proteins in lung cancer diagnosis, prognosis and as drug targets remains unresolved. The aim of this review is to draw the importance of heat shock protein members; Hsp27, Hsp70, Hsp90, Hsp60 and their diagnostic and prognostic implications in lung cancer. Based on the available literature heat shock proteins can serve as biomarkers and anticancer drug targets in the management of lung cancer patients.

Ivermectin inhibits HSP27 and potentiates efficacy of oncogene targeting in tumor models

HSP27 is highly expressed in, and supports oncogene addiction of, many cancers. HSP27 phosphorylation is a limiting step for activation of this protein and a target for inhibition, but its highly disordered structure challenges rational structure-guided drug discovery. We performed multistep biochemical, structural, and computational experiments to define a spherical 24-monomer complex composed of 12 HSP27 dimers with a phosphorylation pocket flanked by serine residues between their N-terminal domains. Ivermectin directly binds this pocket to inhibit MAPKAP2-mediated HSP27 phosphorylation and depolymerization, thereby blocking HSP27-regulated survival signaling and client-oncoprotein interactions. Ivermectin potentiated activity of anti-androgen receptor and anti-EGFR drugs in prostate and EGFR/HER2-driven tumor models, respectively, identifying a repurposing approach for cotargeting stress-adaptive responses to overcome resistance to inhibitors of oncogenic pathway signaling.

Chaperoning STAT3/5 by Heat Shock Proteins: Interest of Their Targeting in Cancer Therapy

While cells from multicellular organisms are dependent upon exogenous signals for their survival, growth, and proliferation, commitment to a specific cell fate requires the correct folding and maturation of proteins, as well as the degradation of misfolded or aggregated proteins within the cell. This general control of protein quality involves the expression and the activity of molecular chaperones such as heat shock proteins (HSPs). HSPs, through their interaction with the STAT3/STAT5 transcription factor pathway, can be crucial both for the tumorigenic properties of cancer cells (cell proliferation, survival) and for the microenvironmental immune cell compartment (differentiation, activation, cytokine secretion) that contributes to immunosuppression, which, in turn, potentially promotes tumor progression. Understanding the contribution of chaperones such as HSP27, HSP70, HSP90, and HSP110 to the STAT3/5 signaling pathway has raised the possibility of targeting such HSPs to specifically restrain STAT3/5 oncogenic functions. In this review, we present how HSPs control STAT3 and STAT5 activation, and vice versa, how the STAT signaling pathways modulate HSP expression. We also discuss whether targeting HSPs is a valid therapeutic option and which HSP would be the best candidate for such a strategy.

Targeting Heat Shock Protein 27 in Cancer: A Druggable Target for Cancer Treatment?

Heat shock protein 27 (HSP27), induced by heat shock, environmental, and pathophysiological stressors, is a multi-functional protein that acts as a protein chaperone and an antioxidant. HSP27 plays a significant role in the inhibition of apoptosis and actin cytoskeletal remodeling. HSP27 is upregulated in many cancers and is associated with a poor prognosis, as well as treatment resistance, whereby cells are protected from therapeutic agents that normally induce apoptosis. This review highlights the most recent findings and role of HSP27 in cancer, as well as the strategies for using HSP27 inhibitors for therapeutic purposes.

A Randomized, Double-Blinded, Phase II Trial of Carboplatin and Pemetrexed with or without Apatorsen (OGX-427) in Patients with Previously Untreated Stage IV Non-Squamous-Non-Small-Cell Lung Cancer: The SPRUCE Trial

BACKGROUND

This randomized, double-blinded, phase II trial evaluated the efficacy of carboplatin and pemetrexed plus either apatorsen, an antisense oligonucleotide targeting heat shock protein (Hsp) 27 mRNA, or placebo in patients with previously untreated metastatic nonsquamous non-small cell lung cancer (NSCLC).

METHODS

Patients were randomized 1:1 to Arm A (carboplatin/pemetrexed plus apatorsen) or Arm B (carboplatin/pemetrexed plus placebo). Treatment was administered in 21-day cycles, with restaging every two cycles, until progression or intolerable toxicity. Serum Hsp27 levels were analyzed at baseline and during treatment. The primary endpoint was progression-free survival (PFS); secondary endpoints included overall survival (OS), objective response rate, and toxicity.

RESULTS

The trial enrolled 155 patients (median age 66 years; 44% Eastern Cooperative Oncology Group performance status 0). Toxicities were similar in the 2 treatment arms; cytopenias, nausea, vomiting, and fatigue were the most frequent treatment-related adverse events. Median PFS and OS were 6.0 and 10.8 months, respectively, for Arm A, and 4.9 and 11.8 months for Arm B (differences not statistically significant). Overall response rates were 27% for Arm A and 32% for Arm B. Sixteen patients (12%) had high serum levels of Hsp27 at baseline. In this small group, patients who received apatorsen had median PFS of 10.8 months, and those who received placebo had median PFS 4.8 months.

CONCLUSION

The addition of apatorsen to carboplatin and pemetrexed was well tolerated but did not improve outcomes in patients with metastatic nonsquamous NSCLC cancer in the first-line setting.

IMPLICATIONS FOR PRACTICE

This randomized, double-blinded, phase II trial evaluated the efficacy of carboplatin and pemetrexed plus either apatorsen, an antisense oligonucleotide targeting heat shock protein 27 mRNA, or placebo in patients with previously untreated metastatic nonsquamous non-small cell lung cancer (NSCLC). The addition of apatorsen to carboplatin and pemetrexed was well tolerated but did not improve outcomes in patients with metastatic nonsquamous NSCLC cancer in the first-line setting.

The single nucleotide variant rs2868371 associates with the risk of mortality in non-small cell lung cancer patients: A multicenter prospective validation

BACKGROUND AND PURPOSE

Definitive radiation therapy (RT) with or without chemotherapy has become the standard treatment for non-metastatic unresectable non-small cell lung cancer (NSCLC). However, treatment outcomes can differ substantially and patients' genetic background could play a crucial role. Potential associations between single-nucleotide polymorphisms (SNP) in Heat shock protein beta-1 (HSPB1) and survival have been reported in prior single-institution retrospective reports.

MATERIALS AND METHODS

The current assay aims to validate such connection in a prospective multicenter study in a European cohort including 181 NSCLC patients. Median follow-up time for all patients was 13 months (range, 3-57 months).

RESULTS

The results obtained show an association between the rs2868371 GG genotype and better overall survival (HR: 0.35; 95%CI: 0.13-0.96; p = 0.042) in multivariate analysis. Two-year overall survival rate was 72% for patients carrying the rs2868371 GG genotype versus 36% for those patients harboring the rs2868371 CC/CG genotypes (p = 0.013). Additionally, the rs2868371 GG genotype was found to be associated with better disease-free survival in the multivariate analysis (HR: 0.36; 95%CI: 0.13-0.99; p = 0.048). In silico analysis of the potential functional SNP suggested significant difference in the affinity of the Glucocorticoid Receptor binding site between alternative allelic variants, confirmed by chromatin immunoprecipitation analysis displaying stronger affinity for the risk allele (C). Furthermore, our findings indicate that the rs2868371 influences (mRNA) HSPB1 expression, offering insight into the regulation of HSPB1 transcription.

CONCLUSION

The functional HSPB1 rs2868371 promoter variant may affect lung cancer survival by regulation of HSPB1 expression levels through glucocorticoid receptor interaction.

Butoxy Mansonone G Inhibits STAT3 and Akt Signaling Pathways in Non-Small Cell Lung Cancers: Combined Experimental and Theoretical Investigations

Epidermal growth factor receptor (EGFR) is the key molecular target for non-small cell lung cancer (NSCLC) due to its major contribution to complex signaling cascades modulating the survival of cancer cells. Targeting EGFR-mediated signaling pathways has been proved as a potential strategy for NSCLC treatment. In the present study, mansonone G (MG), a naturally occurring quinone-containing compound, and its semi-synthetic ether derivatives were subjected to investigate the anticancer effects on human NSCLC cell lines expressing wild-type EGFR (A549) and mutant EGFR (H1975). In vitro cytotoxicity screening results demonstrated that butoxy MG (MG3) exhibits the potent cytotoxic effect on both A549 (IC₅₀ of 8.54 μM) and H1975 (IC₅₀ of 4.21 μM) NSCLC cell lines with low toxicity against PCS201-010 normal fibroblast cells (IC₅₀ of 21.16 μM). Western blotting and flow cytometric analyses revealed that MG3 induces a caspase-dependent apoptosis mechanism through: (i) inhibition of p-STAT3 and p-Akt without affecting upstream p-EGFR and (ii) activation of p-Erk. The 500-ns molecular dynamics simulations and the molecular mechanics combined with generalized Born surface area (MM/GBSA)-based binding free energy calculations suggested that MG3 could possibly interact with STAT3 SH2 domain and ATP-binding pocket of Akt. According to principal component analysis, the binding of MG3 toward STAT3 and Akt dramatically altered the conformation of proteins, especially the residues in the active site, stabilizing MG3 mainly through van der Waals interactions.

Ergosterol peroxide from marine fungus Phoma sp. induces ROS-dependent apoptosis and autophagy in human lung adenocarcinoma cells

As part of our ongoing search for novel therapeutic structures from microorganism, the chemical examination of marine fungus Phoma sp. resulted in the isolation of ergosterol, ergosterol peroxide (EP), and 9,11-dehydroergosterol peroxide (DEP). The bioassay results demonstrated that the three isolates reduced the viability of various cancer cells, with EP being highest in human lung cancer cell line A549 cells. EP induced caspase-dependent apoptosis through mitochondrial damage in A549 cells. Additionally, EP-induced ROS generation and apoptosis were attenuated by ROS-generating enzymes inhibitors and antioxidant N-acetylcysteine, indicated that ROS played an important role in EP-mediated apoptosis in A549 cells. Furthermore, it was observed that EP induced ROS-dependent autophagy, which attenuated apoptosis in A549 cells. On the other hand, EP reduced the LPS/ATP-induced proliferation and migration of A549 cells through attenuated NLRP3 inflammasome activity. Additionally, EP showed synergistic cytotoxic effect with antitumor drug Sorafenib in A549 cell viability inhibition. Furthermore, Micro-Western Array and Western blot analyses demonstrated that the protein levels of EGFR, HSP27, MEK5, AKT1, mTOR, Smad2, Smad3, TAB1, NF-κB, and HIF1-α decreased, while the levels of p-p38α, p-ERK1/2, p-JNK, fibronectin and p27 increased. Collectively, the results of this study demonstrated that EP might be useful to develop a therapeutic candidate for lung cancer complications.

New HSP27 inhibitors efficiently suppress drug resistance development in cancer cells

Drug resistance is an important open problem in cancer treatment. In recent years, the heat shock protein HSP27 (HSPB1) was identified as a key player driving resistance development. HSP27 is overexpressed in many cancer types and influences cellular processes such as apoptosis, DNA repair, recombination, and formation of metastases. As a result cancer cells are able to suppress apoptosis and develop resistance to cytostatic drugs. To identify HSP27 inhibitors we follow a novel computational drug repositioning approach. We exploit a similarity between a predicted HSP27 binding site to a viral thymidine kinase to generate lead inhibitors for HSP27. Six of these leads were verified experimentally. They bind HSP27 and down-regulate its chaperone activity. Most importantly, all six compounds inhibit development of drug resistance in cellular assays. One of the leads – chlorpromazine – is an antipsychotic, which has a positive effect on survival time in human breast cancer. In summary, we make two important contributions: First, we put forward six novel leads, which inhibit HSP27 and tackle drug resistance. Second, we demonstrate the power of computational drug repositioning.

Clinical, prognostic, and therapeutic significance of heat shock protein 27 in bladder cancer

Heat shock protein 27 (HSP27) is highly expressed in many cancers, and its prognostic and predictive value has been reported. HSP27 knockdown using siRNA or OGX-427 (an anti-sense oligonucleotide sequence targeting HSP27) is reported to have anti-cancer effects and to enhance chemosensitivity of cancer cells to chemotherapeutic agents. However, conflicting results have been reported regarding the clinical significance of HSP27 in bladder cancer (BC). Furthermore, long-term suppression of HSP27 has not been investigated in BC. In this study, we investigated the association between HSP27 expression and BC characteristics in 132 BC patient samples, as well as its prognostic value to determine the potential of HSP27 as a clinical biomarker. Additionally, we applied five different shRNAs targeting HSP27 in three invasive BC cell lines to analyze the long-term knockdown effects of HSP27. Our study revealed a significant association between HSP27 expression and adverse pathological characteristics such as high-stage and -grade BC. However, HSP27 expression was not associated with clinical outcomes such as tumor recurrence, progression, and patient survival. Interestingly, although our shRNAs had obvious knockdown effects on HSP27 in BC cells, we did not find consistent effects on apoptosis of BC cells or chemotherapeutic sensitivity of BC cells to cisplatin. Therefore, although HSP27 may be a predictor of adverse pathological characteristics in BC, its role as a prognostic biomarker and therapeutic target seems to be limited.

Role of Krüppel-like factor 4 and heat shock protein 27 in cancer of the larynx

Late detection and lack of standard treatment strategies in larynx cancer patients result in high levels of mortality and poor prognosis. Prognostic stratification of larynx cancer patients based on molecular prognostic tumor biomarkers may lead to more efficient clinical management. Krüppel-like factor 4 (KLF4) and Heat Shock Protein 27 (HSP27) have an important role in tumorigenesis and are considered promising candidate biomarkers for various types of cancer. However, their role in larynx carcinoma remains to be elucidated. The present study aimed to determine KLF4 and HSP27 expression profiles in laryngeal tumors. The protein and mRNA expression levels of KLF4 and HSP27 were evaluated by immunohistochemical and reverse transcription-polymerase chain reaction analyses in 44 larynx carcinoma samples and 21 normal tissue samples, and then correlated with clinical characteristics. A differential expression of KLF4 and HSP27 was observed between normal and tumor tissues. The protein and mRNA expression levels of KLF4 were significantly decreased in larynx squamous cell carcinoma (LSCC) compared with normal tissue, whereas HSP27 was significantly overexpressed in tumor tissues compared with normal tissues, at the protein and mRNA levels. KLF4 expression decreased gradually with tumor progression whereas HSP27 expression increased. A significant difference was observed between stages I and IV. KLF4 and HSP27 exhibit opposite functions and roles in the carcinogenic process of LSCC. Their role in laryngeal cancer initiation and progression emphasizes their use as potential future targets for prognosis and treatment. KLF4 and HSP27 expression levels may act as potential biomarkers in patients with cancer of the larynx.

Sensitization of lung cancer cells by altered dimerization of HSP27

Heat shock protein 27 (HSP27, HSPB1) induces resistance to anticancer drugs in various cancer types, including non-small cell lung cancer (NSCLC). Therefore, pharmacological inhibition of HSP27 in NSCLC may be a good strategy for anticancer therapy. Unlike other HSPs such as HSP90 and HSP70, small molecule approaches for neutralization of HSP27 are not well established because of the absence of an ATP binding domain. Previously, small molecules with altered cross linking activity of HSP27, were identified to inhibit building a large oligomer led to sensitization in combination with radiation and chemotherapeutic drugs. In this study, a chromene compound, J2 that exhibited better cross-linking activity of HSP27 than xanthone compound, SW15 which was previously identified, was yielding sensitization to NSCLC cells with high expression of HSP27 when combined with HSP90 inhibitor and standard anticancer modalities such as taxol and cisplatin. In vivo xenograft system also showed sensitization activity of J2, as well as in vitro cell viability, cell death or apoptosis detection assay. For better druggability, several quinolone compounds, an (bio) isostere of chromone and one of well-known core in many marketed medicine, was designed and synthesized by replacement of oxygen with nitrogen in 4-pyron structure of J2. However, the cross linking activity of HSP27 disappeared by quinolone compounds and the sensitizing effects on the anticancer drugs disappeared as well, suggesting oxygene moiety of 4-pyron structure of J2 may be a pharmacophore for induction of cross linking of HSP27 and sensitization to cancer cells. In conclusion, combination of chemotherapy with small molecules that induces altered cross-linking of HSP27 may be a good strategy to overcome the resistance of anticancer drugs in HSP27-over-expressing cancer cells.

Targeting Heat Shock Proteins in Cancer: A Promising Therapeutic Approach

Heat shock proteins (HSPs) are a large family of chaperones that are involved in protein folding and maturation of a variety of "client" proteins protecting them from degradation, oxidative stress, hypoxia, and thermal stress. Hence, they are significant regulators of cellular proliferation, differentiation and strongly implicated in the molecular orchestration of cancer development and progression as many of their clients are well established oncoproteins in multiple tumor types. Interestingly, tumor cells are more HSP chaperonage-dependent than normal cells for proliferation and survival because the oncoproteins in cancer cells are often misfolded and require augmented chaperonage activity for correction. This led to the development of several inhibitors of HSP90 and other HSPs that have shown promise both preclinically and clinically in the treatment of cancer. In this article, we comprehensively review the roles of some of the important HSPs in cancer, and how targeting them could be efficacious, especially when traditional cancer therapies fail.

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.

Small heat shock proteins in ageing and age-related diseases

Small heat shock proteins (sHSPs) are gatekeepers of cellular homeostasis across species, preserving proteome integrity under stressful conditions. Nonetheless, recent evidence suggests that sHSPs are more than molecular chaperones with merely auxiliary role. In contrast, sHSPs have emerged as central lifespan determinants, and their malfunction has been associated with the manifestation of neurological disorders, cardiovascular disease and cancer malignancies. In this review, we focus on the role of sHSPs in ageing and age-associated diseases and highlight the most prominent paradigms, where impairment of sHSP function has been implicated in human pathology.

Heat-shock protein 27 (HSP27, HSPB1) is synthetic lethal to cells with oncogenic activation of MET, EGFR and BRAF

The small heat-shock protein of 27 kDa (HSP27) is highly expressed in many cancers and is associated with aggressive tumour behaviour, metastasis, poor prognosis and resistance to chemotherapy. We aimed at assessing the role of HSP27 in modulating responses to target therapies. We selected several oncogene-addicted cancer cell lines, which undergo either cell cycle blockade or cell death in response to agents that target the specific oncogene. Surprisingly, HSP27 suppression alone resulted in the apoptotic death of MET-addicted EBC-1 lung cancer cells, epidermal growth factor receptor (EGFR)-addicted colorectal carcinoma (CRC) DiFi cells and BRAF-addicted CRC COLO205 and OXCO-1 and melanoma COLO741 cells, all of which also undergo death when treated with the specific targeted agent. In other cell lines, such as MET-addicted gastric carcinoma MKN45 and EGFR-addicted CRC SW48 lines, where oncogene inhibition only blocked proliferation, HSP27 knockdown made targeted agents switch from cytostatic to cytotoxic activity. Mechanistically, the more the cells were susceptible to HSP27 suppression, the more they were primed for death, as demonstrated by increased levels of mitochondrial outer membrane permeabilization. Priming for death was accompanied by the increase in pro-apoptotic proteins of the BCL2 family and of active caspase-3 and lamin B. Together, these data suggest that oncogene-addicted cells require HSP27 for survival and that HSP27 might interfere with the effectiveness of targeted agents.

Heat shock protein antagonists in early stage clinical trials for NSCLC

INTRODUCTION

Cancer cells have a higher need of chaperones than normal cells to prevent the toxic effects of intracellular protein misfolding and aggregation. Heat shock proteins (Hsps) belong to these chaperones; they are classified into families according to molecular size. Hsps are upregulated in many cancers and inhibition can inhibit tumor growth by destabilizing proteins necessary for tumor survival. In non-small cell lung cancer (NSCLC), there are three different Hsp antagonist classes that are in (early) clinical trials: Hsp90, Hsp70 and Hsp27 inhibitors. Areas covered: The rationale to use Hsp inhibitors in NSCLC will be summarized and phase I-III trials will be reviewed. Expert opinion: Several Hsp90 inhibitors have been tested in phase I-III trials, until now none was positive in unselected NSCLC; therefore development of AUY922, ganetespib and retaspimycin was halted. Results seem more promising in molecularly selected patients, especially in ALK-rearranged NSCLC. Hsp27 is overexpressed in squamous NSCLC and is a mechanism of chemotherapy resistance. The Hsp27 inhibitor apatorsen is now tested in squamous NSCLC. No phase II/III data are known for Hsp70 inhibitors. Combination of Hsp inhibitors with heat shock transcription factor 1 inhibitors or focal adhesion kinase inhibitors might be of interest for future trials.

Heat shock protein 27 is a potential indicator for response to YangZheng XiaoJi and chemotherapy agents in cancer cells

Heat shock protein 27 (HSP27) is a member of the heat shock protein family which has been linked to tumour progression and, most interestingly, to chemotherapy resistance in cancer patients. The present study examined the potential interplay between HSP27 and YangZheng XiaoJi, a traditional Chinese medicine used in cancer treatment. A range of cell lines from different tumour types including pancreatic, lung, gastric, colorectal, breast, prostate and ovarian cancer (both wild-type and resistant) were used. Levels and activation of HSP27 and its potential associated signalling pathways were evaluated by protein array and western blotting. Knockdown of HSP27 in cancer cells was achieved using siRNA. Localisation and co-localisation of HSP27 and other proteins were carried out by immunofluorescence. Cell growth and migration were evaluated in their response to a range of chemotherapeutic agents. The present study first identified, by way of protein array, that YangZheng XiaoJi was able to inhibit the phosphorylation of HSP27 protein in cancer cells. We further demonstrated that HSP27, which is co-localised with caspase-9, can be blocked from localising in focal adhesions and co-localising with caspase-9 by YangZheng XiaoJi. The study also demonstrated that YangZheng XiaoJi was able to sensitise cancer cells including those cells that were resistant to chemotherapy, to chemotherapeutic agents. Finally, knocking down HSP27 markedly reduced the migration of cancer cells and increased the sensitivity of cancer cells to the inhibitory effect on cellular migration by YangZheng XiaoJi. YangZheng XiaoJi can act as an agent in first sensitising cancer cells to chemotherapy and secondly to overcome, to some degree, chemoresistance when used in an appropriate fashion in patients who have active HSP27.

Molecular chaperone Hsp27 regulates the Hippo tumor suppressor pathway in cancer

Heat shock protein 27 (Hsp27) is a molecular chaperone highly expressed in aggressive cancers, where it is involved in numerous pro-tumorigenic signaling pathways. Using functional genomics we identified for the first time that Hsp27 regulates the gene signature of transcriptional co-activators YAP and TAZ, which are negatively regulated by the Hippo Tumor Suppressor pathway. The Hippo pathway inactivates YAP by phosphorylating and increasing its cytoplasmic retention with the 14.3.3 proteins. Gain and loss of function experiments in prostate, breast and lung cancer cells showed that Hsp27 knockdown induced YAP phosphorylation and cytoplasmic localization while overexpression of Hsp27 displayed opposite results. Mechanistically, Hsp27 regulates the Hippo pathway by accelerating the proteasomal degradation of ubiquitinated MST1, the core Hippo kinase, resulting in reduced phosphorylation/activity of LATS1 and MOB1, its downstream effectors. Importantly, our in vitro results were supported by data from human tumors; clinically, high expression of Hsp27 in prostate tumors is correlated with increased expression of YAP gene signature and reduced phosphorylation of YAP in lung and invasive breast cancer clinical samples. This study reveals for the first time a link between Hsp27 and the Hippo cascade, providing a novel mechanism of deregulation of this tumor suppressor pathway across multiple cancers.

Expression of Heat Shock Protein 27 in Melanoma Metastases Is Associated with Overall Response to Bevacizumab Monotherapy: Analyses of Predictive Markers in a Clinical Phase II Study

The aim of this study was to identify potential predictive biomarkers in 35 patients with metastatic melanoma treated with anti-angiogenic bevacizumab monotherapy in a clinical phase II study. The immunohistochemical expression of various angiogenic factors in tissues from primary melanomas and metastases as well as their concentration in blood samples were examined. Strong expression of Heat Shock Protein 27 (HSP27) in metastases correlated significantly with complete or partial response to bevacizumab (p = 0.044). Furthermore, clinical benefit, i.e., complete or partial response or stable disease for at least 6 months, was more frequent in patients with strong expression of HSP27 in primary tumors (p = 0.046). Tissue expression of vascular endothelial growth factor (VEGF-A), its splicing variant VEGF165b or basic fibroblast growth factor (bFGF) did not correlate with response, and the concentration of HSP27, VEGF-A or bFGF measured in blood samples before treatment did not show predictive value. Further, microvessel density, proliferating microvessel density and presence of glomeruloid microvascular proliferations were assessed in sections of primary tumors and metastases. Microvessel density in primary melanomas was significantly higher in patients with clinical benefit than in non-responders (p = 0.042). In conclusion, our findings suggest that strong HSP27 expression in melanoma metastases predicts response to bevacizumab treatment.

A Targetable Molecular Chaperone Hsp27 Confers Aggressiveness in Hepatocellular Carcinoma

Heat shock protein 27 (Hsp27) is an ATP-independent molecular chaperone and confers survival advantages and resistance to cancer cells under stress conditions. The effects and molecular mechanisms of Hsp27 in HCC invasion and metastasis are still unclear. In this study, hepatocellular carcinoma (HCC) tissue array (n = 167) was used to investigate the expression and prognostic relevance of Hsp27 in HCC patients. HCC patients with high expression of Hsp27 exhibited poor prognosis. Overexpression of Hsp27 led to the forced invasion of HCC cells, whereas silencing Hsp27 attenuated invasion and metastasis of HCC cells in vitro and in vivo. We revealed that Hsp27 activated Akt signaling, which in turn promoted MMP2 and ITGA7 expression and HCC metastasis. We further observed that targeting Hsp27 using OGX-427 obviously suppressed HCC metastasis in two metastatic models. These findings indicate that Hsp27 is a useful predictive factor for prognosis of HCC and it facilitates HCC metastasis through Akt signaling. Targeting Hsp27 with OGX-427 may represent an attractive therapeutic option for suppressing HCC metastasis.

Oncolytic Adenovirus Loaded with L-carnosine as Novel Strategy to Enhance the Antitumor Activity

Oncolytic viruses are able to specifically replicate, infect, and kill only cancer cells. Their combination with chemotherapeutic drugs has shown promising results due to the synergistic action of virus and drugs; the combinatorial therapy is considered a potential clinically relevant approach for cancer. In this study, we optimized a strategy to absorb peptides on the viral capsid, based on electrostatic interaction, and used this strategy to deliver an active antitumor drug. We used L-carnosine, a naturally occurring histidine dipeptide with a significant antiproliferative activity. An ad hoc modified, positively charged L-carnosine was combined with the capsid of an oncolytic adenovirus to generate an electrostatic virus-carnosine complex. This complex showed enhanced antitumor efficacy in vitro and in vivo in different tumor models. In HCT-116 colorectal and A549 lung cancer cell lines, the complex showed higher transduction ratio and infectious titer compared with an uncoated oncolytic adenovirus. The in vivo efficacy of the complex was tested in lung and colon cancer xenograft models, showing a significant reduction in tumor growth. Importantly, we investigated the molecular mechanisms underlying the effects of complex on tumor growth reduction. We found that complex induces apoptosis in both cell lines, by using two different mechanisms, enhancing viral replication and affecting the expression of Hsp27. Our system could be used in future studies also for delivery of other bioactive drugs. Mol Cancer Ther; 15(4); 651-60. ©2016 AACR.