Heat shock protein 90 (hsp90) expression and breast cancer

Importance of targeting various cell signaling pathways in solid cancers

Most adult human cancers are solid tumors prevailing in vital organs and lead to mortality all over the globe. Genetic and epigenetic alterations in cancer genes or genes of associated signaling pathways impart the most common characteristic of malignancy, that is, uncontrolled proliferation. Unless the mechanism of action of these cells signaling pathways (involved in cell proliferation, apoptosis, metastasis, and the maintenance of the stemness of cancer stem cells and cancer microenvironment) and their physiologic alteration are extensively studied, it is challenging to understand tumorigenesis as well as develop new treatments and precision medicines. Targeted therapy is one of the most promising strategies for treating various cancers. However, cancer is an evolving disease, and most patients develop resistance to these drugs by acquired mutations or mediation of microenvironmental factors or due to tumor heterogeneity. Researchers are striving to develop novel therapeutic options like combinatorial approaches targeting multiple responsible pathways effectively. Thus, in-depth knowledge of cell signaling and its components remains a critical topic of cancer research. This chapter summarized various extensively studied pathways in solid cancer and how they are targeted for therapeutic strategies.

Revealing Propolis Potential Activity on Inhibiting Estrogen Receptor and Heat Shock Protein 90 Overexpressed in Breast Cancer by Bioinformatics Approaches

Breast cancer is the most commonly diagnosed cancer globally, with the highest incidence of breast cancer occurring in Asian countries including Indonesia. Among the types of breast cancer, the estrogen receptor (ER)-positive subtype which is prominent with estrogen receptor alpha (ERα) and heat shock protein 90 (HSP90) overexpression genes becomes the most prevalent than the others, approximately 75% of all breast cancer cases. ERα and HSP90 play a role in breast cancer activities including breast tumor growth, invasion, and metastasis mechanism. Propolis, a natural bee product, has been explored for its anticancer activity. However, there is lack of studies that evaluated the potential inhibitor from propolis compounds to the ERα and HSP90 proteins. Therefore, this article focuses on examining the correlation between ERα and HSP90's role in breast cancer and investigating the potential of 93 unique propolis compositions in inhibiting these genes in breast cancer using in silico approaches. This study revealed the positive correlation between ERα and HSP90 genes in breast cancer disease development. Furthermore, we also found novel potential bioactive compounds of propolis against breast cancer through binding with ERα and HSP90; they were 3',4',7-trihydroxyisoflavone and baicalein-7-O-β-D glucopyranoside, respectively. Further research on these compounds is needed to elucidate deeper mechanisms and activity in the real biological system to develop new breast cancer drug treatments.

A new vision of photothermal therapy assisted with gold nanorods for the treatment of mammary cancers in adult female rats

Over the past decade, the therapeutic landscape has markedly changed for patients with breast cancers (BCs), yet few studies have evaluated the power of the photothermal therapy (PTT) technique. The present study aimed to assess the potency of 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary cancer treatment with this technique. In total, forty-two adult virgin female Wistar rats were categorized into seven groups, negative control, polyvinylpyrrolidone-capped gold nanorods (PVP-AuNRs) positive control (400 μL per rat ∼ 78 ppm), NIR laser irradiation 808 nm positive control with an intensity of (808 nm NIR CW diode laser, 200 mW cm-2 for 5 min), DMBA-treatment, DMBA-induced mammary cancer group treated with polyvinylpyrrolidone-capped gold nanorods, DMBA-induced mammary cancer group treated with NIR laser irradiation, and DMBA-induced mammary cancer group treated with polyvinylpyrrolidone-capped gold nanorods and NIR laser irradiation. Treatment with polyvinylpyrrolidone-capped gold nanorods and/or NIR laser irradiation was performed after three weeks of DMBA-induced mammary cancer. The mammary tumor lesions in the rat model induced with DMBA are highly invasive. Synthesis and characterization of gold nanorods (AuNRs) with an aspect ratio ranging from 2.8 to 3 were employed to validate the nanostructure and polyvinylpyrrolidone capping and their stability in absorbing near-infrared light. As a result, the therapy strategy, DMBA + PVP-AuNRs + NIR, effectively treated the tumor and halted its growth. The mammary glands were dissected and subjected to biochemical analysis for serum and tissue. Our treatment technique improved the histological aspects of mammary cancer in various forms of mammary cancer detected. Immuno-histochemical localization and TEM images supported these results reflecting the efficacy of this technique. Finally, our findings uncover for the first time the revolutionary effect of the PTT strategy using PVP-capped AuNRs in selectively destroying mammary cancer cells in rats.

Heat shock proteins and cellular senescence in humans: A systematic review

Cellular senescence (CS) is a permanent arrest of cell growth and exit of the cell cycle. It is an important tumor suppression mechanism and has a key role in wound healing, tissue regeneration, and prevention of tissue fibrosis. Despite the short-term benefits of CS, accumulation of senescent cells has deleterious effects and is associated with several pathological age-related phenotypes. As Heat Shock Proteins (HSP) are associated with cyto-protection, their role in longevity and CS became a research interest. However, an overview of the relationship between HSP and CS in humans still lacks in the literature. To provide an overview of the current state of the literature, this systematic review focused on the role of HSP in the development of CS in humans. PubMed, Web of Science and Embase were systematically screened for studies on the relationship between HSP and CS in humans. A total of 14 articles were eligible for inclusion. The heterogeneity and lack of numerical reporting of outcomes obstructed the conduction of a meta-analysis. The results consistently show that HSP depletion results in increased CS, while overexpression of HSP decreases CS, whether in cancer, fibroblasts, or stem cell lines. This systematic review summarized the literature on the prospective role of HSP in the development of CS in humans.

Molecular docking and dynamics simulation study of quinones and pyrones from Alternaria solani and Alternaria alternata with HSP90: an important therapeutic target of cancer

Although cancer continues to be one of the world's major causes of death, current cancer drugs have many serious side effects. There remains a need for new anticancer agents to overcome these shortcomings. Alternaria is one of the most widespread fungal genera, many species of which produce several classes of metabolites with potential polypharmacological activities. A few quinones and pyrones from Alternaria spp. have proven to exert cytotoxic effects against certain cancer cell lines, but their molecular mode of action is not known. The current study aimed to investigate the potential mechanisms that underlie the anticancer activity of a few selected quinones and pyrones from Alternaria solani and Alternaria alternata by molecular docking and dynamic simulation approaches. The selected metabolites were screened for their binding affinity to Heat shock protein 90 (HSP90), which is a known anticancer drug target. Molecular docking studies have revealed that Macrosporin, Altersolanol B, Fonsecin, and Neoaltenuene have good binding affinities with the target protein and the stabilities of the formed complexes were evaluated through molecular dynamics simulations. By analyzing the Root Mean Square Distance (RMSD), Root Mean Square Fluctuation (RMSF), and Principal Component Analysis (PCA) plots obtained from molecular dynamics simulations, this study shows that the complexes of all 4 lead molecules with target protein are stable over a 100 ns period. Molecular Mechanics Poisson-Boltzmann Surface Area (MM-PBSA) calculations were used to compute the binding free energies. The lead molecules were studied using in-silico analysis to determine their drug-likeness based on their Absorption, Distribution, Metabolism, Excretion and Toxicity (ADMET) and physicochemical properties. The results demonstrate that Macrosporin, Fonsecin, and Neoaltenuene could become promising anticancer molecules that target HSP90.Communicated by Ramaswamy H. Sarma.

Protein homeostasis in aging and cancer

Aging is a major risk factor for cancer development. As dysfunction in protein homeostasis, or proteostasis, is a universal hallmark of both the aging process and cancer, a comprehensive understanding of the proteostasis system and its roles in aging and cancer will shed new light on how we can improve health and quality of life for older individuals. In this review, we summarize the regulatory mechanisms of proteostasis and discuss the relationship between proteostasis and aging and age-related diseases, including cancer. Furthermore, we highlight the clinical application value of proteostasis maintenance in delaying the aging process and promoting long-term health.

Exploring breast cancer exosomes for novel biomarkers of potential diagnostic and prognostic importance

The comprehensive bioinformatics analysis of breast cancer exosomes revealed that HSP90AA1, CCT2, and ENO1 were novel hub genes in the giant protein-protein interaction network of 110 exosomal proteins. Exosomes and their cargo such as discrete proteins, nucleic acids, and lipids are having potential role in the pathophysiology of breast cancer (BC). This study showed that the identified hub genes were particularly abundant in GO and KEGG pathways relevant to the positive regulation of telomerase. In addition, these hub genes were found to be considerably overexpressed in breast adenocarcinoma patients compared to healthy controls, and further, this overexpression is linked to the poor prognosis in BC patients. Furthermore, the ROC analysis revealed that CCT2 gene has strong diagnostic and prognostic value for BC. Additionally, this in silico analysis found that the anticancer agents and HSP90 inhibitors such as ganetespib, retaspimycin, and tanespimycin would have considerable potential in the treatment of BC. Overall, this study findings imply that HSP90AA1, a molecular chaperon and CCT2, a chaperonin would serve as diagnostic and prognostic biomarkers, respectively, for BC. However, these findings need to be further confirmed by laboratory and clinical studies for validating their potential applications.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03422-w.

S-glutathionylation of Hsp90 enhances its degradation and correlates with favorable prognosis of breast cancer

Heat shock protein 90 (Hsp90) is a ubiquitous chaperone to interact with numerous proteins to regulate multiple cellular processes, especially during cell proliferation and cell cycle progression. Hsp90 exists in a high level in tumor cells and tissues, and thus serves as a prognostic biomarker or therapeutic target in cancers. We herein report that Hsp90 is subjected to S-glutathionylation, a redox-dependent modification to form a disulfide bond between the tripeptide glutathione and cysteine residues of proteins, primarily at C366 and C412 in the presence of reactive oxygen species. The modification led to the loss of the ATPase activity. The level of Hsp90 was obviously reduced by S-glutathionylation, owing to C-terminus of Hsc70-interacting protein (CHIP)-mediated ubiquitin proteasome system. S-glutathionylation of Hsp90 was found to crosstalk with its C-terminal phosphorylation of Hsp90 that impedes the binding of Hsp90 with CHIP, demonstrating the importance of chaperone code in modulating Hsp90 function. Further biophysical analyses indicated that S-glutathionylation caused structural change of Hsp90, underlying the aforementioned functional regulation. Moreover, in accordance with the analysis of 64 samples collected from patients of breast cancer, the expression level of Hsp90 inversely correlated with the glutathionylated status of Hsp90. The ratio of total expression to glutathionylated status of Hsp90 was coherent to expression of biomarkers in breast cancer sample, potentiating the prognostic value in the cancer treatment.

Heat shock proteins: Biological functions, pathological roles, and therapeutic opportunities

The heat shock proteins (HSPs) are ubiquitous and conserved protein families in both prokaryotic and eukaryotic organisms, and they maintain cellular proteostasis and protect cells from stresses. HSP protein families are classified based on their molecular weights, mainly including large HSPs, HSP90, HSP70, HSP60, HSP40, and small HSPs. They function as molecular chaperons in cells and work as an integrated network, participating in the folding of newly synthesized polypeptides, refolding metastable proteins, protein complex assembly, dissociating protein aggregate dissociation, and the degradation of misfolded proteins. In addition to their chaperone functions, they also play important roles in cell signaling transduction, cell cycle, and apoptosis regulation. Therefore, malfunction of HSPs is related with many diseases, including cancers, neurodegeneration, and other diseases. In this review, we describe the current understandings about the molecular mechanisms of the major HSP families including HSP90/HSP70/HSP60/HSP110 and small HSPs, how the HSPs keep the protein proteostasis and response to stresses, and we also discuss their roles in diseases and the recent exploration of HSP related therapy and diagnosis to modulate diseases. These research advances offer new prospects of HSPs as potential targets for therapeutic intervention.

The Chaperone System in Breast Cancer: Roles and Therapeutic Prospects of the Molecular Chaperones Hsp27, Hsp60, Hsp70, and Hsp90

Breast cancer (BC) is a major public health problem, with key pieces of information needed for developing preventive and curative measures still missing. For example, the participation of the chaperone system (CS) in carcinogenesis and anti-cancer responses is poorly understood, although it can be predicted to be a crucial factor in these mechanisms. The chief components of the CS are the molecular chaperones, and here we discuss four of them, Hsp27, Hsp60, Hsp70, and Hsp90, focusing on their pro-carcinogenic roles in BC and potential for developing anti-BC therapies. These chaperones can be targets of negative chaperonotherapy, namely the elimination/blocking/inhibition of the chaperone(s) functioning in favor of BC, using, for instance, Hsp inhibitors. The chaperones can also be employed in immunotherapy against BC as adjuvants, together with BC antigens. Extracellular vesicles (EVs) in BC diagnosis and management are also briefly discussed, considering their potential as easily accessible carriers of biomarkers and as shippers of anti-cancer agents amenable to manipulation and controlled delivery. The data surveyed from many laboratories reveal that, to enhance the understanding of the role of the CS in BS pathogenesis, one must consider the CS as a physiological system, encompassing diverse members throughout the body and interacting with the ubiquitin–proteasome system, the chaperone-mediated autophagy machinery, and the immune system (IS). An integrated view of the CS, including its functional partners and considering its highly dynamic nature with EVs transporting CS components to reach all the cell compartments in which they are needed, opens as yet unexplored pathways leading to carcinogenesis that are amenable to interference by anti-cancer treatments centered on CS components, such as the molecular chaperones.

Studies on Preformulation and Formulation of JIN-001 Liquisolid Tablet with Enhanced Solubility

This study aimed to develop a heat shock protein 90 (Hsp90) inhibitor liquisolid tablet with improved solubility to overcome low bioavailability issues. As an active pharmaceutical ingredient (API), JIN-001, a novel Hsp90 inhibitor, was reported to have substantial in vitro antiproliferative and in vivo antitumor activity; however, JIN-001 was a crystalline solid with very low solubility in an aqueous solution, and therefore, Capryol 90, which has excellent solubilization ability, was selected as an optimal liquid vehicle based on solubility studies. JIN-001 liquisolid (JLS) powder was successfully prepared by dissolving JIN-001 in Capryol 90 and mixing colloidal silicon dioxide (CSD) used as an oil adsorption agent. The prepared JLS was confirmed to be amorphous. Based on the result of the solubility test of JLS, compared to JIN-001, the solubility of the former was significantly improved in all solvents regardless of pH. JLS tablets were prepared through wet granulation using JIN-001 and stable excipients based on the compatibility test. The developed JLS tablet significantly increased the drug release rate in all tested solutions; however, the liquisolid method had no significant effect on bioavailability in the pharmacokinetics study in beagle dogs. In conclusion, the liquisolid system influenced the solubility and dissolution rate of JIN-001.

Comparative differential cytotoxicity of clinically used SERMs in human cancer lines of different origin and its predictive molecular docking studies of key target genes involved in cancer progression and treatment responses

SERMS like Tamoxifene, 5-hydroxy tamoxifene, raloxifene and endoxifene has been used for the treatment of hormonal imbalances and dependent cancers owing to their action via Estrogen receptors as in the treatment of estrogen sensitive breast cancers. Due to the adverse side effects, modifications and development of the existing or newer SERMS has always been of immense interest. Ormeloxifene, a SERM molecule manufactured by HLL Lifecare Ltd, India as birth control under the trade names Saheli, Novex, and Novex-DS which is also investigated against mastalgia, fibro-adenoma and abnormal uterine bleeding. Anti-cancer effects have been reported in estrogen dependent and independent cancers which shows its wide scope to be implemented in cancer therapy. Current investigation is a comprehensive effort to find the cytotoxic potential of Ormeloxifene in comparison with clinically used four SERMS in twenty six cancer cell lines of different origin using Adriamycin as positive control. Also the computational studies pertaining to selected target/ligand with respect to tumor progression, development, treatment responses and apoptosis. The studies proved effective cytotoxicity of Ormeloxifene on cancer cell lines with lower TGI, GI50 and LC50 values which are significantly comparable. Also the in silico studies proved that the docking score of the compound suggests the interaction of the compound which could tightly regulate key target genes controlling cancer like ER, EGFR kinase, EGFR-cSRC, HDAC-2, PARP-1 and BRAF. This study brings out the superior efficacy of Ormeloxifene compared to other SERMS with proven safety profile to be repositioned as an anti-cancer drug to treat diverse cancer types.

In silico molecular docking and dynamic simulation of eugenol compounds against breast cancer

Breast cancer is one of the most severe problems, and it is the primary cause of cancer-related death in females worldwide. The adverse effects and therapeutic resistance development are among the most potent clinical issues for potent medications for breast cancer treatment. The eugenol molecules have a significant affinity for breast cancer receptors. The aim of the study has been on the eugenol compounds, which has potent actions on Erα, PR, EGFR, CDK2, mTOR, ERBB2, c-Src, HSP90, and chemokines receptors inhibition. Initially, the drug-likeness property was examined to evaluate the anti-breast cancer activity by applying Lipinski's rule of five on 120 eugenol molecules. Further, structure-based virtual screening was performed via molecular docking, as protein-like interactions play a vital role in drug development. The 3D structure of the receptors has been acquired from the protein data bank and is docked with 87 3D PubChem and ZINC structures of eugenol compounds, and five FDA-approved anti-cancer drugs using AutoDock Vina. Then, the compounds were subjected to three replica molecular dynamic simulations run of 100 ns per system. The results were evaluated using root mean square deviation (RMSD), root mean square fluctuation (RMSF), and protein-ligand interactions to indicate protein-ligand complex stability. The results confirm that Eugenol cinnamaldehyde has the best docking score for breast cancer, followed by Aspirin eugenol ester and 4-Allyl-2-methoxyphenyl cinnamate. From the results obtained from in silico studies, we propose that the selected eugenols can be further investigated and evaluated for further lead optimization and drug development.

Trastuzumab Mechanism of Action; 20 Years of Research to Unravel a Dilemma

Trastuzumab as a first HER2-targeted therapy for the treatment of HER2-positive breast cancer patients was introduced in 1998. Although trastuzumab has opened a new avenue to treat patients with HER2-positive breast cancer and other types of cancer, some patients are not responsive or become resistant to this treatment. So far, several mechanisms have been suggested for the mode of action of trastuzumab; however, the findings regarding these mechanisms are controversial. In this review, we aimed to provide a detailed insight into the various mechanisms of action of trastuzumab.

Long non-coding RNA NKILA regulates expression of HSP90α, NF-κB and β-catenin proteins in the MCF-7 breast cancer cell line

Non-coding RNAs are increasingly being investigated and have shown great potential for diagnosis, prognosis and treatment of cancer. Thus, we have investigated a possible regulatory mechanism between NF-κB suppressor-NKILA, and HSP90, NF-κB, and β-catenin molecules in MCF-7 breast cancer cells. HSP90 is an important stress protein and together with β-catenin and NF-κB molecules can be responsible for cancer cell development. However, there is no comprehensive data available on the novel molecule NKILA unlike for HSP90, β-catenin and NF-κB alone. Therefore, we suggest there might be a correlation between NKILA and these proteins. To investigate the NKILA role on HSP90, NF-κB and β-catenin proteins we inhibited the NKILA by using transfection in MCF-7 breast cancer cells. NKILA-siRNA transfected cells were incubated for 5 h. Then, cells were collected and proteins were extracted to be separated by SDS-PAGE. The aforementioned proteins of siRNA transfected group were evaluated by quantification and comparison of their relative expression levels with the control group by immunoblotting. Results showed, HSP90 and NF-κB/p105, NF-κB/p65 and NF-κB/p50 subunits significantly increased while the level of β-catenin decreased after NKILA inhibition. For the first time we have demonstrated that HSP90 and expression levels of beta-catenin are associated with NKILA levels which may be closely related to the canonical NF-κB pathway in MCF-7 cells. These novel findings may have significant implications in cancer cells development and possibly present important hints for the future studies of the cancer cell targeted therapy.

Debio-0932, a second generation oral Hsp90 inhibitor, induces apoptosis in MCF-7 and MDA-MB-231 cell lines

Heat shock protein 90 (Hsp90) is a key chaperone that is abnormally expressed in cancer cells, and therefore, designing novel compounds to inhibit chaperone activities of the Hsp90 is a promising therapeutic approach for cancer drug discovery. Debio-0932 is a second-generation Hsp90 inhibitor that exhibited promising anticancer activity against a wide variety of cancer types with a strong binding affinity for Hsp90 and high oral bioavailability. Anticancer activities of the Debio-0932 were tested in MCF-7 and MDA-MB-231 cell lines. Molecular docking results indicated that Debio-0932 was selectively bound to the ATP binding pocket of the Hsp90 with an estimated free energy of binding - 7.24 kcal/mol. Antiproliferative activity of Debio-0932 was determined by XTT assay and Debio-0932 exhibited a cytotoxic effect on MCF-7 and MDA-MB-231 cells in a time and dose-depended manner. Apoptosis inducer role of Debio-0932 was evaluated in MCF-7 and MDA-MB-231 cells with fluorometric apoptosis/necrosis detection kit. Treatment with Debio-0932 stimulated apoptosis in both breast cancer cell lines. mRNA and protein expression levels of Bax, Bcl-2 and Casp-9 were determined in MCF-7 and MDA-MB-231 cells by RT-PCR and Western blotting respectively. Debio-0932 stimulated the down-regulation of anti-apoptotic protein Bcl-2 and the up-regulation of apoptotic protein Bax and cleavage of Casp-9 in cancer cells. Moreover, the anti-invasive potential of Debio-0932 was evaluated in endothelial cells (HUVEC) by wound-healing assay. Debio-0932 decreased the migration of HUVEC cells as compared to the control group. These results indicate that Debio-0932 is a promising compound to treat triple-negative breast cancer and hormone receptor-positive breast cancer, and their metastases.

Understanding the sources of errors in ex vivo Hsp90 molecular imaging for rapid-on-site breast cancer diagnosis

Overexpression of heat shock protein 90 (Hsp90) on the surface of breast cancer cells makes it an attractive molecular biomarker for breast cancer diagnosis. Before a ubiquitous diagnostic method can be established, an understanding of the systematic errors in Hsp90-based imaging is essential. In this study, we investigated three factors that may influence the sensitivity of ex vivo Hsp90 molecular imaging: time-dependent tissue viability, nonspecific diffusion of an Hsp90 specific probe (HS-27), and contact-based imaging. These three factors will be important considerations when designing any diagnostic imaging strategy based on fluorescence imaging of a molecular target on tissue samples.

Occupational Heat Exposure and Breast Cancer Risk in the MCC-Spain Study

BACKGROUND

Mechanisms linking occupational heat exposure with chronic diseases have been proposed. However, evidence on occupational heat exposure and cancer risk is limited.

METHODS

We evaluated occupational heat exposure and female breast cancer risk in a large Spanish case-control study. We enrolled 1,738 breast cancer cases and 1,910 frequency-matched population controls. A Spanish job-exposure matrix, MatEmEsp, was used to assign estimates of the proportion of workers exposed (P ≥ 25% for at least 1 year) and work time with heat stress (wet bulb globe temperature ISO 7243) for each occupation. We used three exposure indices: ever versus never exposed, lifetime cumulative exposure, and duration of exposure (years). We estimated ORs and 95% confidence intervals (CI), applying a lag period of 5 years and adjusting for potential confounders.

RESULTS

Ever occupational heat exposure was associated with a moderate but statistically significant higher risk of breast cancer (OR 1.22; 95% CI, 1.01-1.46), with significant trends across categories of lifetime cumulative exposure and duration (P _trend = 0.01 and 0.03, respectively). Stronger associations were found for hormone receptor-positive disease (OR ever exposure = 1.38; 95% CI, 1.12-1.67). We found no confounding effects from multiple other common occupational exposures; however, results attenuated with adjustment for occupational detergent exposure.

CONCLUSIONS

This study provides some evidence of an association between occupational heat exposure and female breast cancer risk.

IMPACT

Our results contribute substantially to the scientific literature. Further investigations are needed considering multiple occupational exposures.

Significance of Targeting VEGFR-2 and Cyclin D1 in Luminal-A Breast Cancer

The hormonal luminal-A is the most pre-dominant sub type of breast cancer (BC), and it is associated with a high level of cyclin D1 in Saudi patients. Tamoxifen is the golden therapy for hormonal BC, but resistance of cancer cells to tamoxifen contributes to the recurrence of BC due to many reasons, including high levels of AIB1 and cyclin D1. Overcoming drug resistance could be achieved by exploring alternative targetable therapeutic pathways and new drugs or combinations. The objective of this study was to determine the differentially enriched pathways in 12 samples of Saudi women diagnosed with luminal-A using the PamChip peptide microarray-based kinase activity profiling, and to compare the activity of HAA₂₀₂₀ and dinaciclib with tamoxifen in singles and combinations in the MCF7 luminal-A cell line. Our results of network and pathway analysis of the 12 samples highlighted the importance of VEGFR and CDKs in promoting luminal-A breast cancer. The activation of VEGF signaling via VEGFR-2 leads to activation of PI3K/AKT kinases and an increase of cell survival, and leads to activation of Hsp90, which induces the phosphorylation of FAK1, resulting in cytoskeleton remodeling. PLC-gamma 1 is also activated, leading to FAK-2 and PKC activation. Notably, the G₁/S cell cycle phases and phosphorylation processes contribute to the top seven tumorigenesis processes in the 12 samples. Further, the MTT combination of HAA₂₀₂₀ and dinaciclib showed the best combination index (CI), was more clonogenic against MCF7 cells compared to the other combinations, and it also showed the best selectivity index (SI) in normal MRC5 cells. Interestingly, HAA₂₀₂₀ and dinaciclib showed a synergistic apoptotic and G₁ cell cycle effect in MCF7 cells, which was supported by their synergistic CDK2, cyclin D1, and PCNA inhibition activities. Additionally, the combination showed VEGFR-2 and Hsp90 inhibition activities in MCF7 cells. The results show the significance of targeting VEGFR-2 and cyclin D1 in Saudi luminal-A breast cancer patients, and the effect of combining HAA₂₀₂₀ and dinaciclib on those targets in the MCF7 model. It also warrants further preclinical and in vivo investigations for the combination of HAA₂₀₂₀ and dinaciclib as a possible future second-line treatment for luminal-A breast cancers.

Natural compounds as potential Hsp90 inhibitors for breast cancer-Pharmacophore guided molecular modelling studies

Breast cancer is one of the major impediments affecting women globally. The ATP-dependant heat shock protein 90 (Hsp90) forms the central component of molecular chaperone machinery that predominantly governs the folding of newly synthesized peptides and their conformational maturation. It regulates the stability and function of numerous client proteins that are frequently upregulated and/or mutated in cancer cells, therefore, making Hsp90 inhibition a promising therapeutic strategy for the development of new efficacious drugs to treat breast cancer. In the present in silico investigation, a structure-based pharmacophore model was generated with hydrogen bond donor, hydrogen bond acceptor and hydrophobic features complementary to crucial residues Ala55, Lys58, Asp93, Ile96, Met98 and Thr184 directed at inhibiting the ATP-binding activity of Hsp90. Subsequently, the phytochemical dataset of 3210 natural compounds was screened to retrieve the prospective inhibitors after rigorous validation of the model pharmacophore. The retrieved 135 phytocompounds were further filtered by drug-likeness parameters including Lipinski's rule of five and ADMET properties, then investigated via molecular docking-based scoring. Molecular interactions were assessed using Genetic Optimisation for Ligand Docking program for 95 drug-like natural compounds against Hsp90 along with two clinical drugs as reference compounds - Geldanamycin and Radicicol. Docking studies revealed three phytochemicals are better than the investigated clinical drugs. The reference and hit compounds with dock scores of 48.27 (Geldanamycin), 40.90 (Radicicol), 73.04 (Hit1), 72.92 (Hit2) and 68.12 (Hit3) were further validated for their binding stability through molecular dynamics simulations. We propose that the non-macrocyclic scaffolds of three identified phytochemicals might aid in the development of novel therapeutic candidates against Hsp90-driven cancers.

Heat Shock Proteins (HSPs): A Novel Target for Cancer Metastasis Prevention

Background:

Heat shock proteins (HSPs) are predominant molecular chaperones which are actively involved in the protein folding; which is essential in protecting the structure and functioning of proteins during various stress conditions. Though HSPs have important physiological roles, they have been well known for their roles in various pathogenic conditions such as carcinogenesis; however, limited literature has consolidated its potential as an anti-metastatic drug target.

Objectives:

The present review outlines the role of different HSPs on cancer progression and metastasis; possible role of HSP inhibitors as anti-neoplastic agents is also discussed.

Methods:

The data were collected from PubMed/Medline and other reputed journal databases. The literature that was too old and had no significant role to the review was then omitted.

Results:

Despite their strong physiological functions, HSPs are considered as good markers for cancer prognosis and diagnosis. They have control over survival, proliferation and progression events of cancer including drug resistance, metastasis, and angiogenesis. Since, neoplastic cells are more dependent on HSPs for survival and proliferation, the selectivity and specificity of HSP-targeted cancer drugs remain high. This has made various HSPs potential clinical and experimental targets for cancer prevention. An array of HSP inhibitors has been in trials and many others are in experimental conditions as anticancer and anti-metastatic agents. Several natural products are also being investigated for their efficacy for anticancer and anti-metastatic agents by modulating HSPs.

Conclusion:

Apart from their role as an anticancer drug target, HSPs have shown to be promising targets for the prevention of cancer progression. Extensive studies are required for the use of these molecules as anti-metastatic agents. Further studies in this line may yield specific and effective antimetastatic agents.

Small molecule inhibitor screening identifified HSP90 inhibitor 17-AAG as potential therapeutic agent for gallbladder cancer

Gallbladder cancer (GBC) is a lethal cancer with poor prognosis associated with high invasiveness and poor response to chemotherapy and radiotherapy. New therapeutic approaches are urgently needed in order to improve survival and response rates of GBC patients. We screened 130 small molecule inhibitors on a panel of seven GBC cell lines and identified the HSP90 inhibitor 17-AAG as one of the most potent inhibitory drugs across the different lines. We tested the antitumor efficacy of 17-AAG and geldanamycin (GA) in vitro and in a subcutaneous preclinical tumor model NOD-SCID mice. We also evaluated the expression of HSP90 by immunohistochemistry in human GBC tumors.In vitro assays showed that 17-AAG and GA significantly reduced the expression of HSP90 target proteins, including EGFR, AKT, phospho-AKT, Cyclin B1, phospho-ERK and Cyclin D1. These molecular changes were consistent with reduced cell viability and cell migration and promotion of G2/M cell cycle arrest and apoptosis observed in our in vitro studies.In vivo, 17-AAG showed efficacy in reducing subcutaneous tumors size, exhibiting a 69.6% reduction in tumor size in the treatment group compared to control mice (p < 0.05).The HSP90 immunohistochemical staining was seen in 182/209 cases of GBC (87%) and it was strongly expressed in 70 cases (33%), moderately in 58 cases (28%), and weakly in 54 cases (26%).Our pre-clinical observations strongly suggest that the inhibition of HSP90 function by HSP90 inhibitors is a promising therapeutic strategy for gallbladder cancer that may benefit from new HSP90 inhibitors currently in development.

Predictors of breast cancer cell types and their prognostic power in breast cancer patients

BACKGROUND

Comprehensive understanding of intratumor heterogeneity requires identification of molecular markers, which are capable of differentiating different subpopulations and which also have clinical significance. One important tool that has been addressing this issue is single cell RNA-Sequencing (scRNASeq) that allows the quantification of expression profiles of transcripts in individual cells in a population of cancer cells. Using the expression profiles from scRNASeq, current studies conduct analysis to group cells into different subpopulations using clustering algorithms. In this study, we explore scRNASeq cancer data from a different perspective. We focus on scRNASeq data originating from cancer cells pertaining to a particular cancer type, where the cell type or the subpopulation to which each cell belongs is known. We investigate if the "cell type" of a cancer cell can be predicted based on the expression profiles of a small set of transcripts.

RESULTS

We outline a predictive analytics pipeline to accurately predict 6 breast cancer cell types using single cell gene expression profiles. Instead of building predictive models using the complete human transcripts, the pipeline first eliminates predictors with low expression and low variance. A multinomial penalized logistic regression further reduces the size of the predictors to only 308, out of which 34 are long non-coding RNAs. Tuning of predictive models shows support vector machines and neural networks as the most accurate models achieving close to 98% prediction accuracies. We also find that mixture of protein coding genes and long non-coding RNAs are better predictors compared to when the two sets of transcripts are treated separately. A signature risk score originating from 65 protein coding genes and 5 lncRNA predictors is associated with prognostic survival of TCGA breast cancer patients. This association was maintained when the risk scores were generated using 65 PCGs and 5 lncRNA separately. We further show that predictors restricted to a particular cell type serve as better prognostic markers for the respective patient subtype.

CONCLUSION

Our results show that in general, the breast cancer cell type predictors are also associated with patient survivability and hence have clinical significance.

BIIB021: A novel inhibitor to heat shock protein 90–addicted oncology

Heat shock protein 90 is induced in response to the cell stress. Its overexpression has been reported in many cancers with poor prognosis. It acts as a chaperone to the client proteins, especially the activated oncoproteins in malignancies to protect them from degradation. Heat shock protein 90 inhibition represented anti-cancer effects in many studies. Previous natural product–based compounds are limited by their association with target toxicities. BIIB021 is an orally available, fully synthetic novel small-molecule heat shock protein 90 inhibitor that has shown strong antitumor activities in a large number of preclinical models and is now under clinical investigation. This review will summarize its therapeutic effects and highlight the prospect of targeting heat shock protein 90 in the cancer therapy.

Localisation Microscopy of Breast Epithelial ErbB-2 Receptors and Gap Junctions: Trafficking after γ-Irradiation, Neuregulin-1β, and Trastuzumab Application

In cancer, vulnerable breast epithelium malignance tendency correlates with number and activation of ErbB receptor tyrosine kinases. In the presented work, we observe ErbB receptors activated by irradiation-induced DNA injury or neuregulin-1β application, or alternatively, attenuated by a therapeutic antibody using high resolution fluorescence localization microscopy. The gap junction turnover coinciding with ErbB receptor activation and co-transport is simultaneously recorded. DNA injury caused by 4 Gray of 6 MeV photon γ-irradiation or alternatively neuregulin-1β application mobilized ErbB receptors in a nucleograde fashion—a process attenuated by trastuzumab antibody application. This was accompanied by increased receptor density, indicating packing into transport units. Factors mobilizing ErbB receptors also mobilized plasma membrane resident gap junction channels. The time course of ErbB receptor activation and gap junction mobilization recapitulates the time course of non-homologous end-joining DNA repair. We explain our findings under terms of DNA injury-induced membrane receptor tyrosine kinase activation and retrograde trafficking. In addition, we interpret the phenomenon of retrograde co-trafficking of gap junction connexons stimulated by ErbB receptor activation.

Elevated levels of ribosomal proteins eL36 and eL42 control expression of Hsp90 in rhabdomyosarcoma

Mammalian 90 kDa heat shock protein (Hsp90) is a ubiquitous molecular chaperone whose expression is selectively upregulated during stress, although the precise control mechanism of this increase is yet to be fully elucidated. We used polysome profiling to show that Hsp90α mRNA is selectively translated, while global translation is inhibited during heat stress. Furthermore, we have identified 2 ribosomal proteins, eL36 and eL42 that modulate Hsp90α expression under both normal and heat shock conditions. Importantly, we noted that expression of eL36 and eL42 is elevated in a panel of human rhabdomyosarcomas where it drives high expression of Hsp90 and modulates sensitivity of these cells to an Hsp90 inhibitor 17-AAG.

Recent trends in microRNA research into breast cancer with particular focus on the associations between microRNAs and intrinsic subtypes

MicroRNAs (miRNAs) are short non-coding RNAs that regulate the function of target genes at the post-transcriptional phase. miRNAs are considered to have roles in the development, progression and metastasis of cancer. Recent studies have indicated that particular miRNA signatures are correlated with tumor aggressiveness, response to drug therapy and patient outcome in breast cancer. On the other hand, in routine clinical practice, the treatment regimens for breast cancer are determined based on the intrinsic subtype of the primary tumor. Previous studies have shown that miRNA expression profiles of each intrinsic subtypes of breast cancer differ. In hormone receptor-positive/human epidermal growth factor receptor 2 (HER2)-negative breast cancer, miRNA expressions are found to be correlated with endocrine therapy resistance, progesterone receptor expression and heat shock protein activity. Some miRNAs are associated with resistance to HER2-targeted therapy and HER3 expression in HER2-positive breast cancer. In triple-negative breast cancer, miRNA expressions are found to be associated with BRCA mutations, immune system, epithelial-mesenchymal transition, cancer stem cell properties and androgen receptor expression. As it has been clarified that the expression levels and functions of miRNA differ among the various subtypes of breast cancer, and it is necessary to take account of the characteristics of each breast cancer subtype during research into the roles of miRNA in breast cancer. In addition, the discovery of the roles played by miRNAs in breast cancer might provide new opportunities for the development of novel strategies for diagnosing and treating breast cancer.

Molecular modeling and synthesis of new 1,5-diphenylpyrazoles as breast cancer cell growth inhibitors

New pyrazoles have been synthesized and evaluated as breast cancer cell growth inhibitors. Condensation of the substituted pyrazole-4-carbaldehyde1with acetophenone and chloroacetophenone afforded α, β-unsaturated ketones2and3, respectively. Compounds2and3were subjected to different reactions using hydrazine hydrate, substituted hydrazine hydrate, hydroxylamine,o-phenylenediamine, malononitrile under different conditions affording 4-substituted pyrazole derivatives4–28. Structure elucidation of these compounds was conducted using IR,1H NMR,13C NMR, mass spectral data and elemental analysis. Antitumor activity of target compounds was tested against MCF-7 cell line (human breast cancer). Compounds4,10and20show significant antitumor activity against breast cancer. Docking was performed with protein 1UYK to study the binding mode of the designed compounds.

Quantitative tissue proteomic investigation of invasive ductal carcinoma of breast with luminal B HER2 positive and HER2 enriched subtypes towards potential diagnostic and therapeutic biomarkers

Worldwide, breast cancer is one of the frequently diagnosed cancers in women with high mortality if not diagnosed at early stage. Although biomarker discoveries through various proteomic approaches have been studied in breast cancer, a limited number of studies have explored the invasive ductal carcinoma with Luminal B HER2 positive (LB) and HER2 enriched (HE) subtypes. The present study employed the complementary quantitative proteomic approaches to find a panel of markers that could discriminate LB and HE subtypes as well as early (ES) and late stages (LS) of these subtypes. A total of 67 and 68 differentially expressed proteins were identified by DIGE for the subtype and stage wise categories, respectively. Multivariate statistical analysis was employed to identify the set of most significant proteins, which could discriminate between these two subtypes and also early and late stages under study. Immunoblotting and MRM based validation in a separate cohort of samples confirmed that panel of biosignatures for LB are APOA1, GELS, HS90B, EF1A1, NHRF1 and PRDX3 and for HE are PRDX1, CATD, CALR, ATPB and CH60. For the diagnosis of early and late stages the potential markers are TPM4, CATD, PRDX3, ANXA3, HSPB1 and CALR, TRFE, GELS, CH60, CAPG, NHRF1, 1433G, GRP78 respectively.

Modulation of expression of heat shock proteins and apoptosis by Flueggea leucopyrus (Willd) decoction in three breast cancer phenotypes

Background

During the past few years, there has been an increasing interest among the Traditional and Folk medical practitioners of Sri Lanka in the use of a decoction prepared from Flueggea leucopyrus (Willd.) for treating various cancers including breast cancer. In the present study, the cytotoxicity of this decoction and its effects on Heat Shock Protein (HSP) expression and apoptosis were compared in three breast cancer phenotypes, to scientifically evaluate if a decoction prepared from F. leucopyrus (Willd.) is useful for the treatment of breast cancer.

Methods

Cytotoxic potential of the F. leucopyrus decoction was determined by evaluating its effects in MCF-7, MDA-MB-231 and SKBR-3 breast cancer cell lines, and MCF-10A (non-cancerous) breast cell line, by use of the Sulphorhodamine (SRB) assay. The effect of the decoction on HSP gene expression in the above cells was evaluated by (a) Real time reverse transcription PCR (RT-PCR) and (b) Immunofluorescence analysis of HSP protein expression. Effects of the decoction on apoptosis were evaluated by (a) fluorescent microscopic examination of apoptosis related morphological changes and (b) DNA fragmentation (c) Caspase 3/7 assay.

Results

F. leucopyrus decoction can mediate significant cytotoxic effects in all three breast cancer cells phenotypes (IC₅₀ values: 27.89, 99.43, 121.43 μg/mL at 24 h post incubation periods, for MCF-7, MDA-MB-231, SKBR-3 respectively) with little effect in the non-cancerous breast cell line MCF-10A (IC₅₀: 570.4 μg/mL). Significant (*P <0.05) inhibitions of HSP 90 and HSP 70 expression were mediated by the decoction in MCF-7 and MDA-MB-231, with little effect in the SKBR-3 cells. Clear apoptotic morphological changes on Acridine orange/Ethidium bromide staining and DNA fragmentation were observed in all three breast cancer cell lines. Caspase 3/7 were significantly (*P <0.05) activated only in MDA-MB-231 and SKBR-3 cells indicating caspase dependent apoptosis in these cells and caspase independent apoptosis in MCF-7 cells.

Conclusions

Modulation of HSP 90 and HSP 70 expressions is a possible mechanism by which the decoction of F. leucopyrus mediates cytotoxic effects MCF-7 and MDA-MB-231 cells. This effect appears to correlate with enhanced apoptosis in these cells. In SKBR-3 cells, mechanisms other than HSP inhibition may be utilized to a greater extent by the decoction to mediate the observed cytotoxic effects. Overall findings suggest that the decoction has the potential to be exploited further for effective treatment of breast cancer.

Selection and Characterization of Single Chain Antibody Fragments Specific for Hsp90 as a Potential Cancer Targeting Molecule

Heat shock proteins play an essential role in facilitating malignant transformation and they have been recognized as important factors in human cancers. One of the key elements of the molecular chaperones machinery is Hsp90 and it has recently become a target for anticancer therapeutic approaches. The potential and importance of Hsp90-directed agents becomes apparent when one realizes that disruption of Hsp90 function may influence over 200 oncogenic client proteins. Here, we described the selection and characterization of Hsp90-specific antibody fragments from commercially available Tomlinson I and J phage display libraries. The affinities of Hsp90-binding scFv variants were measured using SPR method. Then, based on the best clone selected, we performed the affinity maturation procedure and obtained valuable Hsp90-specific clones. The selected binders were expressed and applied for immunostaining, ELISA and SPR analysis using model cancer cell lines. All performed experiments confirmed the ability of selected antibodies to interact with the Hsp90. Therefore, the presented Hsp90-specific scFv, might be a starting point for the development of a novel antibody-based strategy targeting cancer.

Standard of care and promising new agents for triple negative metastatic breast cancer

Triple negative breast cancer (TNBC) is a cluster of heterogeneous diseases, all of them sharing the lack of expression of estrogen and progesterone receptors and HER2 protein. They are characterized by different biological, molecular and clinical features, including a poor prognosis despite the increased sensitivity to the current cytotoxic therapies. Several studies have identified important molecular features which enable further subdivision of this type of tumor. We are drawing from genomics, transcription and translation analysis at different levels, to improve our knowledge of the molecular alterations along the pathways which are activated during carcinogenesis and tumor progression. How this information should be used for the rational selection of therapy is an ongoing challenge and the subject of numerous research studies in progress. Currently, the vascular endothelial growth factor (VEGF), poly (ADP-ribose) polymerase (PARP), HSP90 and Aurora inhibitors are most used as targeting agents in metastatic setting clinical trials. In this paper we will review the current knowledge about the genetic subtypes of TNBC and their different responses to conventional therapeutic strategies, as well as to some new promising molecular target agents, aimed to achieve more tailored therapies.

Screening of multiple myeloma by polyclonal rabbit anti-human plasmacytoma cell immunoglobulin

Antibody-based immunotherapy has been effectively used for tumor treatment. However, to date, only a few tumor-associated antigens (TAAs) or therapeutic targets have been identified. Identification of more immunogenic antigens is essential for improvements in multiple myeloma (MM) diagnosis and therapy. In this study, we synthesized a polyclonal antibody (PAb) by immunizing rabbits with whole human plasmacytoma ARH-77 cells and identified MM-associated antigens, including enlonase, adipophilin, and HSP90s, among others, via proteomic technologies. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay showed that 200 µg/mL PAb inhibits the proliferation of ARH-77 cells by over 50% within 48 h. Flow cytometric assay indicated that PAb treatment significantly increases the number of apoptotic cells compared with other treatments (52.1% vs. NS, 7.3% or control rabbit IgG, 9.9%). In vivo, PAb delayed tumor growth and prolonged the lifespan of mice. Terminal deoxynucleotidyl transferase dUTP nick end labeling assay showed that PAb also induces statistically significant changes in apoptosis compared with other treatments (P<0.05). We therefore conclude that PAb could be used for the effective screening and identification of TAA. PAb may have certain anti-tumor functions in vitro and in vivo. As such, its combination with proteomic technologies could be a promising approach for sieving TAA for the diagnosis and therapy of MM.