Spotlight on 17-AAG as an Hsp90 inhibitor for molecular targeted cancer treatment

DAB2IP down-regulates HSP90AA1 to inhibit the malignant biological behaviors of colorectal cancer

Background

Studies have shown that DAB2IP inhibits cancer progression, while HSP90AA1 promotes cancer progression. However, the specific regulatory mechanism of DAB2IP and HSP90AA1 in colorectal cancer (CRC) is not clear. Our aim is to investigate the role and mechanism of DAB2IP and HSP90AA1 in the development of CRC.

Methods

We used bioinformation to analyze the interaction between DAB2IP and HSP90AA1 and predict their downstream pathways. Then, a series of in vitro and in vivo experiments were conducted to reveal the role of DAB2IP and HSP90AA1 in the invasion and metastasis of colorectal cancer, and flow cytometry was used to explore their effects on apoptosis.

Results

Loss of DAB2IP was associated with poor prognosis of CRC. In contrast, elevated expression of HSP90AA1 was associated with the malignant behavior of CRC. The present study demonstrated a negative correlation between DAB2IP and HSP90AA1. Using bioinformatic analysis, we scanned SRP9 which was highly expressed in CRC, as a co-related gene of DAB2IP and HSP90AA1. Mechanistically, DAB2IP promoted apoptosis through HSP90AA1/SRP9/ASK1/JNK signaling axis in CRC.

Conclusions

These findings provide evidence that DAB2IP-based therapy may enhance the anticancer effect of HSP90AA1 inhibitors, and combined targeting of DAB2IP and HSP90AA1 may be a powerful treatment strategy to combat CRC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09596-z.

Tackling Drug Resistance and Other Causes of Treatment Failure in Leishmaniasis

Leishmaniasis is a tropical infectious disease caused by the protozoan Leishmania parasite. The disease is transmitted by female sand flies and, depending on the infecting parasite species, causes either cutaneous (stigmatizing skin lesions), mucocutaneous (destruction of mucous membranes of nose, mouth and throat) or visceral disease (a potentially fatal infection of liver, spleen and bone marrow). Although more than 1 million new cases occur annually, chemotherapeutic options are limited and their efficacy is jeopardized by increasing treatment failure rates and growing drug resistance. To delay the emergence of resistance to existing and new drugs, elucidating the currently unknown causes of variable drug efficacy (related to parasite susceptibility, host immunity and drug pharmacokinetics) and improved use of genotypic and phenotypic tools to define, measure and monitor resistance in the field are critical. This review highlights recent progress in our understanding of drug action and resistance in Leishmania, ongoing challenges (including setbacks related to the COVID-19 pandemic) and provides an overview of possible strategies to tackle this public health challenge.

Synergistic inhibition of the growth of MDA-MB-231 cells in triple-negative breast cancer by salinomycin combined with 17-AAG and its mechanism

Salinomycin (SAL), a typical ion carrier antibiotic, inhibits tumor growth and metastasis by inducing apoptosis or autophagy in cancer or cancer stem cells and thus overcomes drug resistance. 17-allylamino-17-demethoxygeldanamycin (17-AAG), a heat shock protein Hsp90 competitive inhibitor, also has a role in inhibiting tumor development. However, their combination on the growth of breast cancer cells and its specific mechanism remains to be elucidated. The present study tested the influence of SAL and 17-AAG on cell growth, apoptosis and autophagy by MTT assays, Annexin V-FITC and propidium iodide double staining assay and immunoelectron microscopy. The influence of SAL and 17-AAG on proteomics was investigated by isobaric tag for relative and absolute quantitation. It was found that SAL combined with 17-AAG synergistically inhibited the cell growth and induced the apoptosis in a concentration-dependent manner, with the expression of caspase 3 and Bcl-2 were decreased while the expression of Bax was increased. In addition, SAL combined with 17-AAG inhibited autophagy, with the expression of microtubule-associated protein 1 light chain 3, Beclin1, p62 being decreased. Mechanistically, SAL combined with 17-AAG synergistically inhibited the reactive oxygen species/JNK signaling pathway. In conclusion, SAL combined with 17-AAG had a synergistic inhibitory effect on cell growth of breast cancer via inducing apoptosis and inhibiting autophagy. The present study might provide a new strategy for potential clinical application of SAL as a new anti-tumor drug especially as a drug combination with other molecular targeting therapeutics.

Heat Shock Proteins and HSF1 in Cancer

Fitness of cells is dependent on protein homeostasis which is maintained by cooperative activities of protein chaperones and proteolytic machinery. Upon encountering protein-damaging conditions, cells activate the heat-shock response (HSR) which involves HSF1-mediated transcriptional upregulation of a group of chaperones - the heat shock proteins (HSPs). Cancer cells experience high levels of proteotoxic stress due to the production of mutated proteins, aneuploidy-induced excess of components of multiprotein complexes, increased translation rates, and dysregulated metabolism. To cope with this chronic state of proteotoxic stress, cancers almost invariably upregulate major components of HSR, including HSF1 and individual HSPs. Some oncogenic programs show dependence or coupling with a particular HSR factor (such as frequent coamplification of HSF1 and MYC genes). Elevated levels of HSPs and HSF1 are typically associated with drug resistance and poor clinical outcomes in various malignancies. The non-oncogene dependence ("addiction") on protein quality controls represents a pancancer target in treating human malignancies, offering a potential to enhance efficacy of standard and targeted chemotherapy and immune checkpoint inhibitors. In cancers with specific dependencies, HSR components can serve as alternative targets to poorly druggable oncogenic drivers.

Hsp90 inhibition sensitizes DLBCL cells to cisplatin

Purpose

Platinum-containing therapy is standard treatment for relapsed Diffuse Large B-Cell Lymphoma (DLBCL). However, the efficacy of treatment is limited by drug resistance leading to relapse. Cisplatin resistance has been linked to impairments of the DNA damage response, and several DNA repair proteins have been identified as clients of the molecular chaperone Hsp90. Here, we investigated the combinatory treatment of cisplatin and the Hsp90 inhibitor, 17AAG, in DLBCL cells to evaluate if inhibition of Hsp90 could sensitize DLBCL cells to cisplatin treatment.

Methods

Cell viability was assessed for cisplatin and 17AAG as monotherapies and for 25 different combinations in 7 DLBCL cell lines, where the Bliss Independence Model and the Combination Index were applied to assess their interaction. Induction of apoptosis and DNA damage response were evaluated by measuring Annexin V and γH2AX levels after 48 h of exposure.

Results

17AAG synergized with cisplatin in DLBCL cells as detected in both interaction assessment models, resulting in a lower viability after 48 h for the combination-treated cells compared to both vehicle and single drug-treated cells. The combination also induced a stronger apoptotic response and an increase in DNA damage in 17AAG, cisplatin- and combination-treated cells compared to vehicle-treated cells, with the effect of the combination generally being higher than compared to both single drugs.

Conclusion

This study demonstrates that 17AAG sensitizes DLBCL cells to cisplatin treatment. This effect is correlated with increased apoptotic and DNA damage response, potentially mediated by downregulation of Hsp90 clients in DNA repair pathways. Thus, cisplatin resistance could plausibly be overcome by combining the treatment with an Hsp90 inhibiting drug.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00280-022-04407-5.

Exploring the oncogenic and therapeutic target potential of the MYB-TYK2 fusion gene in B-cell acute lymphoblastic leukemia

TYK2-rearrangements have recently been identified in high-risk acute lymphoblastic leukemia (HR-ALL) cases and are associated with poor outcome. Current understanding of the leukemogenic potential and therapeutic targetability of activating TYK2 alterations in the ALL setting is unclear, thus further investigations are warranted. Consequently, we developed in vitro, and for the first time, in vivo models of B-cell ALL from a patient harboring the MYB-TYK2 fusion gene. These models revealed JAK/STAT signaling activation and the oncogenic potential of the MYB-TYK2 fusion gene in isolation. High throughput screening identified the HDAC inhibitor, vorinostat and the HSP90 inhibitor, tanespimycin plus the JAK inhibitor, cerdulatinib as the most effective agents against cells expressing the MYB-TYK2 alteration. Evaluation of vorinostat and cerdulatinib in pre-clinical models of MYB-TYK2-rearranged ALL demonstrated that both drugs exhibited anti-leukemic effects and reduced the disease burden in treated mice. Importantly, these findings indicate that activating TYK2 alterations can function as driver oncogenes rather than passenger or secondary events in disease development. In addition, our data provide evidence for use of vorinostat and cerdulatinib in the treatment regimens of patients with this rare yet aggressive type of high-risk ALL that warrants further investigation in the clinical setting.

HSP90AB1 Promotes the Proliferation, Migration, and Glycolysis of Head and Neck Squamous Cell Carcinoma

Background: Head and neck squamous cell carcinoma (HNSCC) is the 6th most common cancer worldwide. Heat shock protein 90 alpha family class B member 1 (HSP90AB1) is highly expressed in a variety of cancers and is associated with poor prognosis, however, its role in HNSCC is still poorly understood. This study aimed to explore the function HSP90AB1 played in HNSCC progression. Methods: The expression level of HSP90AB1 in HNSCC was analyzed by bioinformatics analysis and western blotting, and its relationship with clinicopathological parameters was analyzed by bioinformatics analysis and immunohistochemistry. Three stable HSP90AB1 knockdown HNSCC cell lines were constructed by lentiviral transfection. The effect of HSP90AB1 knockdown on the proliferation and migration of HNSCC cells was tested by CCK-8 assay, EdU incorporation assay, colony formation assay, nude mouse xenograft models, transwell migration assay, wound healing assay, and western blotting. The effect of HSP90AB1 knockdown on glycolysis in HNSCC cells was assessed by quantitative real-time PCR and related assay kits. Finally, the levels of Akt and phospho-Akt (Ser473) proteins after HSP90AB1 knockdown were detected by western blotting. Results: HSP90AB1 was highly expressed in HNSCC and associated with T grade, lymph node metastasis, and prognosis. Knockdown of HSP90AB1 inhibited the proliferation, migration, and glycolysis of HNSCC, and reduced the level of phospho-Akt. Conclusion: HSP90AB1 functions as an oncogene in HNSCC, and has the potential to become a prognostic factor and therapeutic target.

CircSTK40 contributes to recurrent implantation failure via modulating the HSP90/AKT/FOXO1 axis

Increasing evidence has revealed a close relationship between non-coding RNAs and recurrent implantation failure (RIF). However, the role of circular RNAs (circRNAs) in RIF pathogenesis remains largely unknown. Microarray analyses were used to identify the differentially expressed circRNA-circSTK40. Functional experiments, including decidualization induction and terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) assay, were performed to determine the effects of circSTK40 on human endometrial stromal cells (ESCs). The interactions between circSTK40 and proteins were investigated by RNA pull-down, RNA immunoprecipitation, and co-immunoprecipitation (coIP) assays. We observed that circSTK40 expression was upregulated in the RIF midluteal-phase endometrial samples. circSTK40 overexpression in ESCs inhibited the decidualization process but concurrently enhanced cell survival during stress. Mechanistically, circSTK40 directly bound to HSP90 and CLU, thus functioning as a scaffold to block their interactions and hinder the proteasomal degradation of HSP90. The resulting high levels of HSP90 led to the activation of the AKT pathway and downregulation of FOXO1 expression. Inhibitors of AKT (MK-2206) and HSP90 (17AAG) both abolished the effects of circSTK40 overexpression in ESCs and increased the decidualization levels in a dose-dependent manner. Our findings indicate a novel epigenetic mechanism for RIF pathogenesis involving circSTK40 activity and provide a foundation for targeted treatments in patients with low endometrial receptivity.

Effects of 17-AAG on the RIP1/RIP3/MLKL pathway during the development of heart failure following myocardial infarction in rats

In a previous study, we suggested that the Hsp90 inhibitor 17-AAG prevents cardiac dysfunction in the failing heart following myocardial infarction in rats. Although it is assumed that the RIP1/RIP3/MLKL necroptotic pathway, which comprises client proteins for Hsp90, is involved; however, the relationship between the cardioprotective effects of 17-AAG and the activity of the cardiac RIP1/RIP3/MLKL necrosome-associated proteins in the failing heart following myocardial infarction remained unclear. Therefore, the levels of phosphorylated MLKL after myocardial infarction with or without Hsp90 inhibitor treatment were measured. Myocardial infarction was induced by ligation of the coronary artery (CAL) in Wistar rats. 17-AAG was injected from the 2nd to the 8th week after myocardial infarction. The administration of 17-AAG attenuated the cardiac dysfunction, hypertrophy, and fibrosis at the 8th week after CAL, simultaneously lessening the increases in the expression and phosphorylation levels of RIP1, RIP3, and MLKL in the area of the left ventricular muscle without infarct. These results indicate that the activation of the RIP1/RIP3/MLKL pathway is a common event in the development of chronic heart failure. Furthermore, our findings suggest that the effects of 17-AAG treatment on the improvement of cardiac function in rats after myocardial infarction is related to the attenuation of this RIP1/RIP3/MLKL pathway.

Recent advances in nanomedicine-based delivery of histone deacetylase inhibitors for cancer therapy

Histone deacetylase inhibitors (HDACi) are cancer therapeutics that operate at the epigenetic level and which have recently gained wide attention. However, the applications of HDACi are generally hindered by their poor physicochemical characteristics and unfavorable pharmacokinetic profile. Inspired by the approved nanomedicine-based drugs in the market, nanocarriers could provide a resort to circumvent the limitations imposed by HDACi. Enhanced tumor targeting, improved cellular uptake and reduced toxicity are major advantages offered by HDACi-loaded nanoparticles. More importantly, site-specific drug delivery can be achieved via engineered stimuli-responsive nanosystems. In this review we elucidate the anticancer mechanisms of HDACi and their structure-activity relationships, with a special focus on their nanomedicine-based delivery, different drug loading concepts and their implications.

Recent advances in heat shock proteins in cancer diagnosis, prognosis, metabolism and treatment

Heat shock proteins (HSPs) are a group of proteins, also known as molecular chaperones, which participate in protein folding and maturation in response to stresses or high temperature. According to their molecular weights, mammalian HSPs are classified into HSP27, HSP40, HSP60, HSP70, HSP90, and large HSPs. Previous studies have revealed that HSPs play important roles in oncogenesis and malignant progression because they can modulate all six hallmark traits of cancer. Because of this, HSPs have been propelled into the spotlight as biomarkers for cancer diagnosis and prognosis, as well as an exciting anticancer drug target. However, the relationship between the expression level of HSPs and their activity and cancer diagnosis, prognosis, metabolism and treatment is not clear and has not been completely established. Herein, this review summarizes and discusses recent advances and perspectives in major HSPs as biomarkers for cancer diagnosis, as regulators for cancer metabolism or as therapeutic targets for cancer therapy, which may provide new directions to improve the accuracy of cancer diagnosis and develop more effective and safer anticancer therapeutics.

Gas generating microspheres for immediate release of Hsp90 inhibitor aiming at postembolization hypoxia in transarterial chemoembolization therapy of hepatocellular carcinoma

CO₂ gas generating poly(lactic-co-glycolic acid) (PLGA) microsphere (MS) was designed for rapid release of tanespimycin (17-AAG) in transarterial chemoembolization (TACE) treatment of hepatocellular carcinoma (HCC). As poorly water-soluble drug is generally released from PLGA MS in a sustained manner, the drug release profile should be controlled according to its clinical indications. In current study, responding to immediate increase in hypoxia inducible factor-1α (HIF-1α) level under hypoxia state followed by embolization of tumor feeding arteries, sodium bicarbonate (NaHCO₃) was added to PLGA/17-AAG MS for fast drug release by CO₂ gas generation in slightly acidic tumor microenvironment. With the aid of NaHCO₃, initial burst release of 17-AAG was available without losing the micron-size and spherical shape of designed MS for embolization of artery. Acid-responsive CO₂ gas generation and subsequent immediate release of 17-AAG from MS were successfully verified. PLGA/17-AAG/NaHCO₃ MS-treated group exhibited higher antiproliferation and apoptosis induction efficacies in McA-RH7777 and SNU-761 cells. McA-RH7777 tumor-implanted rats treated by TACE using PLGA/17-AAG/NaHCO₃ MS presented a complete therapeutic response. All these findings suggest that developed tumor microenvironment-responsive gas-generating MS can be efficiently applied to TACE therapy of HCC.

Anticancer activity and toxicity of new quaternary ammonium geldanamycin derivative salts and their mixtures with potentiators

Geldanamycin (GDM) has been modified by different type neutral/acidic/basic substituents (1–7) and by quinuclidine motif (8), transformed into ammonium salts (9–13) at C(17). These compounds have been characterised by spectroscopic and x-ray methods. Derivative 8 shows better potency than GDM in MCF-7, MDA-MB-231, A549 and HeLa (IC₅₀s = 0.09–1.06 µM). Transformation of 8 into salts 9–13 reduces toxicity (by 11-fold) at attractive potency, e.g. MCF-7 cell line (IC₅₀∼2 µM). Our studies show that higher water solubility contributes to lower toxicity of salts than GDM in healthy CCD39Lu and HDF cells. The use of 13 mixtures with potentiators PEI and DOX enhanced anticancer effects from IC₅₀∼2 µM to IC₅₀∼0.5 µM in SKBR-3, SKOV-3, and PC-3 cancer cells, relative to 13. Docking studies showed that complexes between quinuclidine-bearing 8–13 and Hsp90 are stabilised by extra hydrophobic interactions between the C(17)-arms and K58 or Y61 of Hsp90.

Ailanthus Altissima-derived Ailanthone enhances Gastric Cancer Cell Apoptosis by Inducing the Repression of Base Excision Repair by Downregulating p23 Expression

Chemotherapy plays an irreplaceable role in the treatment of GC, but currently available chemotherapeutic drugs are not ideal. The application of medicinal plants is an important direction for new drug discovery. Through drug screening of GC organoids, we determined that ailanthone has an anticancer effect on GC cells in vitro and in vivo. We also found that AIL can induce DNA damage and apoptosis in GC cells. Further transcriptome sequencing of PDX tissue indicated that AIL inhibited the expression of XRCC1, which plays an important role in DNA damage repair, and the results were also confirmed by western blotting. In addition, we found that AIL inhibited the expression of P23 and that inhibition of P23 decreased the expression of XRCC1, indicating that AIL can regulate XRCC1 via P23. The results of coimmunoprecipitation showed that AIL can inhibit the binding of P23 and XRCC1 to HSP90. These findings indicate that AIL can induce DNA damage and apoptosis in GC cells. Meanwhile, AIL can decrease XRCC1 activity by downregulating P23 expression to inhibit DNA damage repair. The present study sheds light on the potential application of new drugs isolated from natural medicinal plants for GC therapy.

Targeting heat shock protein 90 for anti-cancer drug development

INTRODUCTION

Heat shock proteins (HSPs) constitute a large family of proteins involved in protein folding and maturation. HSP expression is induced by heat shock or other stressors including cellular damage and hypoxia. The major groups, which are classified based on their molecular weight, include HSP27, HSP40, HSP60, HSP70, HSP90, and large HSP (HSP110 and glucose-regulated protein 170). HSPs play a significant role in cellular proliferation, differentiation, survival, apoptosis, and carcinogenesis. The human HSP90 family consists of five members and has a strong association with cancer.

OBJECTIVES

The primary objective is to review the important functions of heat shock protein 90 in cancer, especially as an anti-cancer drug target.

RESULTS

The HSP90 proteins not only play important roles in cancer development, progression, and metastasis, but also have potential clinical use as biomarkers for cancer diagnosis or assessing disease progression, and as therapeutic targets for cancer therapy. In this chapter, we discuss the roles of HSP90 in cancer biology and pharmacology, focusing on HSP90 as an anti-cancer drug target. An understanding of the functions and molecular mechanisms of HSP90 is critical for enhancing the accuracy of cancer diagnosis as well as for developing more effective and less toxic chemotherapeutic agents.

CONCLUSION

We have provided an overview of the complex relationship between cancer and HSP90. HSP90 proteins play an important role in tumorigenesis and may be used as potential clinical biomarkers for the diagnosis and predicting prognostic outcome of patients with cancer. HSP90 proteins may be used as therapeutic targets for cancer therapy, prompting discovery and development of novel chemotherapeutic agents.

HSP90 inhibitor NVP-BEP800 affects stability of SRC kinases and growth of T-cell and B-cell acute lymphoblastic leukemias

T-cell and B-cell acute lymphoblastic leukemias (T-ALL, B-ALL) are aggressive hematological malignancies characterized by an accumulation of immature T- or B-cells. Although patient outcomes have improved, novel targeted therapies are needed to reduce the intensity of chemotherapy and improve the prognosis of high-risk patients. Using cell lines, primary cells and patient-derived xenograft (PDX) models, we demonstrate that ALL cells viability is sensitive to NVP-BEP800, an ATP-competitive inhibitor of Heat shock protein 90 (HSP90). Furthermore, we reveal that lymphocyte-specific SRC family kinases (SFK) are important clients of the HSP90 chaperone in ALL. When PDX mice are treated with NVP-BEP800, we found that there is a decrease in ALL progression. Together, these results demonstrate that the chaperoning of SFK by HSP90 is involved in the growth of ALL. These novel findings provide an alternative approach to target SRC kinases and could be used for the development of new treatment strategies for ALL.

Cell Surface GRP94 as a Novel Emerging Therapeutic Target for Monoclonal Antibody Cancer Therapy

Glucose-regulated protein 94 (GRP94) is an endoplasmic reticulum (ER)-resident member of the heat shock protein 90 (HSP90) family. In physiological conditions, it plays a vital role in regulating biological functions, including chaperoning cellular proteins in the ER lumen, maintaining calcium homeostasis, and modulating immune system function. Recently, several reports have shown the functional role and clinical relevance of GRP94 overexpression in the progression and metastasis of several cancers. Therefore, the current review highlights GRP94’s physiological and pathophysiological roles in normal and cancer cells. Additionally, the unmet medical needs of small chemical inhibitors and the current development status of monoclonal antibodies specifically targeting GRP94 will be discussed to emphasize the importance of cell surface GRP94 as an emerging therapeutic target in monoclonal antibody therapy for cancer.

Progress in the Development of Eukaryotic Elongation Factor 2 Kinase (eEF2K) Natural Product and Synthetic Small Molecule Inhibitors for Cancer Chemotherapy

Eukaryotic elongation factor 2 kinase (eEF2K or Ca2+/calmodulin-dependent protein kinase, CAMKIII) is a new member of an atypical α-kinase family different from conventional protein kinases that is now considered as a potential target for the treatment of cancer. This protein regulates the phosphorylation of eukaryotic elongation factor 2 (eEF2) to restrain activity and inhibit the elongation stage of protein synthesis. Mounting evidence shows that eEF2K regulates the cell cycle, autophagy, apoptosis, angiogenesis, invasion, and metastasis in several types of cancers. The expression of eEF2K promotes survival of cancer cells, and the level of this protein is increased in many cancer cells to adapt them to the microenvironment conditions including hypoxia, nutrient depletion, and acidosis. The physiological function of eEF2K and its role in the development and progression of cancer are here reviewed in detail. In addition, a summary of progress for in vitro eEF2K inhibitors from anti-cancer drug discovery research in recent years, along with their structure-activity relationships (SARs) and synthetic routes or natural sources, is also described. Special attention is given to those inhibitors that have been already validated in vivo, with the overall aim to provide reference context for the further development of new first-in-class anti-cancer drugs that target eEF2K.

Nanotechnology and Nanocarrier-Based Drug Delivery as the Potential Therapeutic Strategy for Glioblastoma Multiforme: An Update

Simple Summary

Glioblastoma multiforme (GBM) are among the most lethal tumors. The highly invasive nature and presence of GBM stem cells, as well as the blood brain barrier (BBB) which limits chemotherapeutic drugs from entering the tumor mass, account for the high chance of treatment failure. Recent developments have found that nanoparticles can be conjugated to liposomes, dendrimers, metal irons, or polymeric micelles, which enhance the drug-loaded compounds to efficiently penetrate the BBB, thus offering new possibilities for overcoming GBM stem cell-mediated resistance to chemotherapy and radiation therapy. In addition, there have been new emerging strategies that use nanocarriers for successful GBM treatment in animal models. This review highlights the recent development of nanotechnology and nanocarrier-based drug delivery for treatment of GBMs, which may be a promising therapeutic strategy for this tumor entity.

Abstract

Glioblastoma multiforme (GBM) is the most common and malignant brain tumor with poor prognosis. The heterogeneous and aggressive nature of GBMs increases the difficulty of current standard treatment. The presence of GBM stem cells and the blood brain barrier (BBB) further contribute to the most important compromise of chemotherapy and radiation therapy. Current suggestions to optimize GBM patients’ outcomes favor controlled targeted delivery of chemotherapeutic agents to GBM cells through the BBB using nanoparticles and monoclonal antibodies. Nanotechnology and nanocarrier-based drug delivery have recently gained attention due to the characteristics of biosafety, sustained drug release, increased solubility, and enhanced drug bioactivity and BBB penetrability. In this review, we focused on recently developed nanoparticles and emerging strategies using nanocarriers for the treatment of GBMs. Current studies using nanoparticles or nanocarrier-based drug delivery system for treatment of GBMs in clinical trials, as well as the advantages and limitations, were also reviewed.

17-Allylamino-demethoxygeldanamycin Used Alone or in Combination with Sodium Orthovanadate Promotes Apoptosis and Inhibits Invasion of SH-SY5Y Cells by Modulating PIWIL2

Neuroblastoma (NB) is one of the most common extracranial solid tumors of childhood and accounts for 15% of cancer deaths. Even with the multimodality treatment protocols, the advanced-stage tumor overall 5-year survival rate is less than 50%. Therefore, novel drug therapy targeting cellular signal transduction pathways regulating the apoptotic cascade may be important for the treatment of drug-resistant NB. In our previous studies, we have demonstrated that 5 μM sodium orthovanadate (SOV) induced the apoptosis of SH-SY5Y cells. 17-Allylamino-demethoxygeldanamycin (17-AAG) is a geldanamycin- (GA-) derived heat shock protein 90 (Hsp90) inhibitor, and it has been shown to have potent antitumor activity in head and neck cancers. However, the effect of 17-AAG on the apoptosis of NB cells has not been reported. Therefore, the purpose of this study was to determine the effects of 17-AAG and SOV on the growth and invasion of SH-SY5Y cells in vitro and explore the related mechanism. In this study, we first investigated the antiviability effect of 17-AAG on SH-SY5Y cells, then studied the cell apoptosis and invasion influenced by 17-AAG and SOV, and assessed the role of PIWI-Like2 (PIWIL2) and piRNA-PIWI signaling in it. The results showed that 5 μM 17-AAG inhibited cell growth and viability and induced apoptosis in SH-SY5Y cells. Both 17-AAG and SOV reduced the level of PIWIL2 and Bcl-xl proteins and inhibited the invasion of SH-SY5Y cells. In addition, the combined use of the two drugs had greater effect than the single use of any drug.

Activation-induced cytidine deaminase: in sickness and in health

Activation Induced cytidine Deaminase (AID) is an essential enzyme of the adaptive immune system. Its canonical activity is restricted to B lymphocytes, playing an essential role in the diversification of antibodies by enhancing specificity and changing affinity. This is possible through its DNA deaminase function, leading to mutations in DNA. In the last decade, AID has been assigned an additional function: that of a powerful DNA demethylator. Adverse cellular conditions such as chronic inflammation can lead to its deregulation and overexpression. It is an important driver of B-cell lymphoma due to its natural ability to modify DNA through deamination, leading to mutations and epigenetic changes. However, the deregulation of AID is not restricted to lymphoid cells. Recent findings have provided new insights into the role that this protein plays in the development of non-lymphoid cancers, with some research shedding light on novel AID-driven mechanisms of cellular transformation. In this review, we provide an updated narrative of the normal physiological functions of AID. Additionally, we review and discuss the recent research studies that have implicated AID in carcinogenesis in varying tissue types including lymphoid and non-lymphoid cancers. We review the mechanisms, whereby AID promotes carcinogenesis and highlight important areas of future research.

Synthesis, structure and anticancer activity of new geldanamycin amine analogs containing C(17)- or C(20)- flexible and rigid arms as well as closed or open ansa-bridges

The nucleophilic attack of amines at C(17) or C(17)/C(20) positions of geldanamycin's (GDM) benzoquinone, via initial 1,4-Michael conjugate addition mechanism, yield new analogs with closed or open ansa-bridges (1-31), respectively. X-ray structures of analogs 22 and 24 reveals an unexpected arrangement of the ansa-bridge in solid (conformer B), that is located between those of conformers A, prevailing in solution (trans-lactam), and C, crucial at binding to Hsp90 (cis-lactam). The structure of a new-type conformer B allows to better understand the molecular recognition mechanism between the GDM analogs and the target Hsp90. Combined analysis of: anticancer test results (SKBR-3, SKOV-3, PC-3, U-87, A-549) and those performed in normal cells (HDF), K_D values and docking modes at Hsp90 as well as clogP parameters, reveals that the rigid C(17)-arm (piperidyl, cyclohexyl) with a H-bond acceptor as carbonyl group together with a lipophilicity clogP∼3 favor high potency of analogs, even up to IC₅₀ ∼0.08 μM, at improved selectivity (SI_HDF > 30), when compared to GDM. The most active 25 show higher anticancer potency than 17-AAG (in SKOV-3 and A-549) as well as reblastatin (in SKBR-3 and SKOV-3). Opening of the ansa-bridge within GDM analogs, at the best case, decreases activity (IC₅₀∼2 μM) and toxicity in HDF cells (SI_HDF∼2-3), relative to GDM.

Kruppel-like factor 4 upregulates matrix metalloproteinase 13 expression in chondrocytes via mRNA stabilization

Matrix metalloproteinase 13 (MMP13) is indispensable for normal skeletal development and is also a principal proteinase responsible for articular joint pathologies. MMP13 mRNA level needs to be tightly regulated in both positive and negative manners to achieve normal development and also to prevent joint destruction. We showed previously that Kruppel-like factor 4 (KLF4) strongly induces the expression of members of the MMP family of genes including that for MMP13 in cultured chondrocytes. Through expression-based screening of approximately 400 compounds, we identified several that efficiently downregulated MMP13 gene expression induced by KLF4. Compounds grouped as topoisomerase inhibitors (transcriptional inhibitors) downregulated MMP13 expression levels, which proved the validity of our screening method. In this screening, trichostatin A (TSA) was identified as one of the most potent repressors. Mechanistically, increased MMP13 mRNA levels induced by KLF4 were not mainly caused by increased rates of RNA polymerase II-mediated MMP13 transcription, but arose from escaping mRNA decay. TSA treatment almost completely blunted the effect of KLF4. Importantly, KLF4 was detected in chondrocytes at the joint destruction sites in a rodent model of osteoarthritis. Our results partially explain how KLF4 regulates numerous proteinase gene expressions simultaneously in chondrocytes. Also, these observations suggest that modulation of KLF4 activity or expression could be a novel therapeutic target for osteoarthritis.

Enzymatic biosynthesis and biological evaluation of novel 17-AAG glucoside as potential anti-cancer agents

A novel 17-allylamino-17-demethoxygeldanamycin (17-AAG) glucoside (1) was obtained from in vitro enzymatic glycosylation using a UDP-glycosyltransferase (YjiC). The water-solubility of compound 1 was approximately 10.5 times higher than that of the substrate, 17-AAG. Compound 1 showed potential anti-proliferative activities against five human cancer cell lines, with IC₅₀ values ranging from 5.26 to 28.52 μM. Further studies also indicated that compound 1 could inhibit the growth of CNE-2Z cells by inducing the degradation of Hsp90 client proteins (Akt, c-Raf, Bcl-2, and HIF-1α). In addition, compound 1 showed greater potential anti-tumor efficacy than 17-AAG in nude mice xenografted with CNE-2Z cells. Therefore, we suggest that in vitro enzymatic glycosylation is a powerful approach for the structural optimization of 17-AAG.

Combination of HSP90 and autophagy inhibitors promotes hepatocellular carcinoma apoptosis following incomplete thermal ablation

The present study evaluated the effect of combining inhibitors (17-AAG) of heat shock protein 90 (HSP90) and autophagy (3-MA) on apoptosis using an incomplete thermal ablation animal model. A total of 28 orthotopic mice with hepatocellular carcinoma were randomly divided into 4 groups to receive different drug interventions. Following palliative laser ablation, changes in autophagy, apoptosis and Akt/mTOR expression levels were assessed in tumors. Compared with the controls, the 17-AAG-treated mice exhibited significantly decreased expression levels of phosphorylated (p)-Akt and p-mTOR with enhanced autophagy and apoptosis; no marked increases in the expression levels of p-Akt and p-mTOR were observed in the 3-MA-treated mice, with no significant changes in autophagy; however, apoptosis was enhanced. No significant decreases in p-Akt and p-mTOR or any increase in autophagy were observed in the mice receiving a combination of 17-AAG and 3-MA, but they did exhibit a marked increase in apoptosis. Compared with 17-AAG alone, the combination of 17-AAG and 3-MA resulted in a marked increase in apoptosis without enhanced autophagy. In the incomplete ablation model, the effects of autophagy and apoptosis are antagonistic. The combined use of 17-AAG and 3-MA can significantly promote apoptosis and is worthy of further study.

17‑AAG synergizes with Belinostat to exhibit a negative effect on the proliferation and invasion of MDA‑MB‑231 breast cancer cells

Breast cancer is one of the most common malignancies that threaten the health of women. Although there are a few chemotherapies for the clinical treatment of breast cancer, these therapies are faced with the problems of drug-resistance and metastasis. Drug combination can help to reduce the adverse side effects of chemotherapies using single drugs, and also help to overcome common drug-resistance during clinical treatment of breast cancer. The present study reported the synergistic effect of the heat shock protein 90 inhibitor 17-AAG and the histone deacetylase 6 inhibitor Belinostat in triple-negative breast cancer (TNBC) MDA-MB-231 cells, by detection of proliferation, apoptosis and cell cycle arrest following treatment with this combination. Subsequently, RNA sequencing (RNA-seq) data was collected and analyzed to investigate the synergistic mechanism of this combination. Based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathways revealed by RNA-seq data analysis, a wound-healing assay was used to investigate the effect of this combination on the migration of MDA-MB-231 cells. Compared with treatment with 17-AAG or Belinostat alone, both the viability inhibition and apoptosis rate of MDA-MB-231 cells were significantly enhanced in the combination group. The combination index values were <1 in three concentration groups. Revealed by the RNA-seq data analysis, the most significantly enriched KEGG pathways in the combination group were closely associated with cell migration. Based on these findings, the anti-migration effect of this combination was investigated. It was revealed that the migration of MDA-MB-231 cells was significantly suppressed in the combination group compared with in the groups treated with 17-AAG or Belinostat alone. In terms of specific genes, the mRNA expression levels of TEA domain family proteins were significantly decreased in the combination group, whereas the phosphorylation of YY1 associated protein 1 and modulator of VRAC current 1 was significantly enhanced in the combination group. These alterations may help to explain the anti-migration effect of this combination. Belinostat has already been approved as a treatment for T-cell lymphoma and 17-AAG is undergoing clinical trials. These findings could provide a beneficial reference for the clinical treatment of patients with TNBC.

Block-And-Lock Strategies to Cure HIV Infection

Today HIV infection cannot be cured due to the presence of a reservoir of latently infected cells inducing a viral rebound upon treatment interruption. Hence, the latent reservoir is considered as the major barrier for an HIV cure. So far, efforts to completely eradicate the reservoir via a shock-and-kill approach have proven difficult and unsuccessful. Therefore, more research has been done recently on an alternative block-and-lock functional cure strategy. In contrast to the shock-and-kill strategy that aims to eradicate the entire reservoir, block-and-lock aims to permanently silence all proviruses, even after treatment interruption. HIV silencing can be achieved by targeting different factors of the transcription machinery. In this review, we first describe the underlying mechanisms of HIV transcription and silencing. Next, we give an overview of the different block-and-lock strategies under investigation.

PADI3 plays an antitumor role via the Hsp90/CKS1 pathway in colon cancer

BACKGROUND

CKS1 is highly expressed in colon cancer tissues, and is essential for cancer cell proliferation. The downstream molecular mechanism of CKS1 has been fully studied, but the upstream regulatory mechanism of it is still unclear. Earlier research found that PADI3 plays its anti-tumor roles via suppress cell proliferation, in this study, we found that the expression pattern of PADI3 and CKS1 are negatively correlated in colon cancer tissues, and overexpression of PADI3 can partly reverse CKS1 induced cancer cell proliferation. However, the regulatory mechanism of PADI3 and CKS1 in the tumorigenesis of colon cancer is still unclear and need to do further research.

METHODS

Western blot and real-time PCR were used to detect the expression levels of genes. CCK-8 and colony formation assays were used to examine cell proliferation and colony formation ability. Overexpression and rescue experiments were used to study the molecular mechanism of CKS1 in colon cancer cells, BALB/c nude mice were used to study the function of CKS1 in vivo.

RESULTS

CKS1 is highly expressed in colon cancer tissues, and the overexpression of CKS1 promotes cell proliferation and colony formation in both HCT116 (originating from primary colon cancer) and SW620 (originating from metastatic tumor nodules of colon cancer) cells. CKS1-expressing HCT116 cells produced larger tumors than the control cells. The expression pattern of PADI3 and CKS1 are negatively correlation in clinical samples of colon cancer, further study indicates that PADI3 can significantly decrease Hsp90 and CKS1 expression, and Hsp90 is essential for PADI3 to downregulate CKS1expression in colon cancer cells.

CONCLUSIONS

PADI3 exerts its antitumor activity by inhibiting Hsp90 and CKS1 expression, and Hsp90 is essential for PADI3 to suppress CKS1 expression.

Heat Shock Protein 90 as a Prognostic Marker and Therapeutic Target for Adrenocortical Carcinoma

Background: Adrenocortical carcinoma (ACC) is a rare tumor entity with restricted therapeutic opportunities. HSP90 (Heat Shock Protein 90) chaperone activity is fundamental for cell survival and contributes to different oncogenic signaling pathways. Indeed, agents targeting HSP90 function have shown therapeutic efficacy in several cancer types. We have examined the expression of HSP90 in different adrenal tumors and evaluated the use of HSP90 inhibitors in vitro as possible therapy for ACC. Methods: Immunohistochemical expression of HSP90 isoforms was investigated in different adrenocortical tumors and associated with clinical features. Additionally, a panel of N-terminal (17-allylamino-17-demethoxygeldanamycin (17-AAG), luminespib, and ganetespib) and C-terminal (novobiocin and silibinin) HSP90 inhibitors were tested on various ACC cell lines. Results: Within adrenocortical tumors, ACC samples exhibited the highest expression of HSP90β. Within a cohort of ACC patients, HSP90β expression levels were inversely correlated with recurrence-free and overall survival. In functional assays, among five different compounds tested luminespib and ganetespib induced a significant decrease in cell viability in single as well as in combined treatments with compounds of the clinically used EDP-M scheme (etoposide, doxorubicin, cisplatin, mitotane). Inhibition of cell viability correlated furthermore with a decrease in proliferation, in cell migration and an increase in apoptosis. Moreover, analysis of cancer pathways indicated a modulation of the ERK1/2-and AKT-pathways by luminespib and ganetespib treatment. Conclusions: Our findings emphasize HSP90 as a marker with prognostic impact and promising target with N-terminal HSP90 inhibitors as drugs with potential therapeutic efficacy toward ACC.