Hsp90 as a therapeutic target in patients with oesophageal carcinoma

Synthesis and characterization of 64Cu-labeled Geldanamycin derivative for imaging HSP90 expression in breast cancer

Heat shock protein 90 (HSP90) plays a crucial role in cancer cell growth and metastasis by stabilizing overexpressed signaling proteins. Inhibiting HSP90 has emerged as a promising anti-cancer strategy. In this study, we aimed to develop and characterize a HSP90-targeted molecular imaging probe, [64Cu]Cu-DOTA-BDA-GM, based on a specific HSP90 inhibitor, geldanamycin (GM), for PET imaging of cancers. GM is modified at the C-17 position with 1,4-butane-diamine (BDA) and linked to 1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) for 64Cu radiolabeling. We evaluated the probe's specific binding to HSP90-expressing cells using Chinese hamster ovary (CHO) cells and breast cancer cells including MDA-MB-231, MDA-MB-435S, MCF7, and KR-BR-3 cell lines. A competition study with non-radioactive GM-BDA yielded an IC50 value of 1.35 ± 0.14 nM, underscoring the probe's affinity for HSP90. In xenograft models of MDA-MB-231 breast cancer, [64Cu]Cu-DOTA-BDA-GM showcased targeted tumor localization, with significant radioactivity observed up to 18 h post-injection. Blocking studies using unlabeled GM-BDA and treatment with the anticancer drug Vorinostat (SAHA), which can affect the expression and activity of numerous proteins, such as HSPs, confirmed the specificity and sensitivity of the probe in cancer targeting. Additionally, PET/CT imaging in a lung metastasis mouse model revealed increased lung uptake of [64Cu]Cu-DOTA-BDA-GM in metastatic sites, significantly higher than in non-metastatic lungs, illustrating the probe's ability to detect metastatic breast cancer. In conclusion, [64Cu]Cu-DOTA-BDA-GM represents a sensitive and specific approach for identifying HSP90 expression in breast cancer and metastases, offering promising implications for clinical diagnosis and monitoring.

Crystal structure of the middle and C-terminal domains of Hsp90α labeled with a coumarin derivative reveals a potential allosteric binding site as a drug target

The 90 kDa heat-shock protein (Hsp90) is an abundant molecular chaperone that is essential to activate, stabilize and regulate the function of a plethora of client proteins. As drug targets for the treatment of cancer and neurodegenerative diseases, Hsp90 inhibitors that bind to the N-terminal ATP-binding site of Hsp90 have shown disappointing efficacy in clinical trials. Thus, allosteric regulation of the function of Hsp90 by compounds that interact with its middle and C-terminal (MC) domains is now being pursued as a mechanism to inhibit the ATPase activity and client protein-binding activity of Hsp90 without concomitant induction of the heat-shock response. Here, the crystal structure of the Hsp90αMC protein covalently linked to a coumarin derivative, MDCC {7-diethylamino-3-[N-(2-maleimidoethyl)carbamoyl]coumarin}, which is located in a hydrophobic pocket that is formed at the Hsp90αMC hexamer interface, is reported. MDCC binding leads to the hexamerization of Hsp90, and the stabilization and conformational changes of three loops that are critical for its function. A fluorescence competition assay demonstrated that other characterized coumarin and isoflavone-containing Hsp90 inhibitors compete with MDCC binding, suggesting that they could bind at a common site or that they might allosterically alter the structure of the MDCC binding site. This study provides insights into the mechanism by which the coumarin class of allosteric inhibitors potentially disrupt the function of Hsp90 by regulating its oligomerization and the burial of interaction sites involved in the ATP-dependent folding of Hsp90 clients. The hydrophobic binding pocket characterized here will provide new structural information for future drug design.

Potential Molecular Targets in the Setting of Chemoradiation for Esophageal Malignancies

Although the development of effective combined chemoradiation regimens for esophageal cancers has resulted in statistically significant survival benefits, the majority of patients treated with curative intent develop locoregional and/or distant relapse. Further improvements in disease control and survival will require the development of individualized therapy based on the knowledge of host and tumor genomics and potentially harnessing the host immune system. Although there are a number of gene targets that are amplified and proteins that are overexpressed in esophageal cancers, attempts to target several of these have not proven successful in unselected patients. Herein, we review our current state of knowledge regarding the molecular pathways implicated in esophageal carcinoma, and the available agents for targeting these pathways that may rationally be combined with standard chemoradiation, with the hope that this commentary will guide future efforts of novel combinations of therapy.

Patient-derived xenograft: a developing tool for screening biomarkers and potential therapeutic targets for human esophageal cancers

Esophageal cancer (EC) represents a human malignancy, diagnosed often at the advanced stage of cancer and resulting in high morbidity and mortality. The development of precision medicine allows for the identification of more personalized therapeutic strategies to improve cancer treatment. By implanting primary cancer tissues into immunodeficient mice for expansion, patient-derived xenograft (PDX) models largely maintain similar histological and genetic representations naturally found in patients' tumor cells. PDX models of EC (EC-PDX) provide fine platforms to investigate the tumor microenvironment, tumor genomic heterogeneity, and tumor response to chemoradiotherapy, which are necessary for new drug discovery to combat EC in addition to optimization of current therapeutic strategies for EC. In this review, we summarize the methods used for establishing EC-PDX models and investigate the utilities of EC-PDX in screening predictive biomarkers and potential therapeutic targets. The challenge of this promising research tool is also discussed.

Inhibition of heat shock protein 90 suppresses squamous carcinogenic progression in a mouse model of esophageal cancer

PURPOSE

Heat shock protein 90 (Hsp90), a potential therapeutic target, has been widely recognized in vitro and in vivo in immunodeficient mice. Here, we aimed to evaluate the role of Hsp90 in an immunocompetent mouse model of esophageal squamous cell cancer (ESCC).

METHODS

The carcinogen 4-nitroquinoline 1-oxide (4NQO) was used to induce ESCC in C57BL/6 mice. Cancer progression was analyzed through observation of appearance, hematoxylin-eosin staining, immunohistochemical detection, and terminal dUTP nick-end labeling analysis.

RESULTS

4NQO led to the progressive appearance of preneoplastic and tumoral lesions in the esophagus, with 100 % incidence of ESCC in situ occurring only after 16 weeks of carcinogen exposure. Most of these lesions evolved spontaneously into highly invasive ESCC even after 4NQO withdrawal (weeks 16-22). Interestingly, there was marked upregulation of Hsp90 and its client proteins in tumoral lesions at 22 weeks. Hsp90 inhibition by intraperitoneal injection of SNX-2112 over the following 2 weeks downregulated AKT and cyclin D1 expression, leading to significant reduction in tumor incidence and prevention of ESCC progression. Moreover, SNX-2112 treatment decreased proliferating cell nuclear antigen expression and increased the number of apoptotic cells in ESCC tissues.

CONCLUSIONS

Our in vivo findings support the contribution of Hsp90 to ESCC progression, which was achieved by stimulating apoptosis and inhibition of cell proliferation, and provide a strong rationale for further evaluation of Hsp90 inhibitors for treating ESCC.

Treatment of malignant, non-resectable, epithelial origin esophageal tumours with the humanized anti-epidermal growth factor antibody nimotuzumab combined with radiation therapy and chemotherapy

BACKGROUND

Over-expression of epidermal growth factor receptor in esophageal cancer is associated with poor prognosis. The present study was conducted to evaluate safety and preliminary efficacy of nimotuzumab, a humanized anti-EGFR antibody in combination with radiation and chemotherapy in advanced esophageal tumours.

PATIENTS AND METHODS

A Phase II clinical trial was conducted, where patients received cisplatin, 5-fluorouracil, and radiotherapy, either alone or combined with six weekly infusions of nimotuzumab at the dose of 200 mg. Safety was the primary endpoint. The antitumoral objective response rate was the secondary endpoint. Epidermal growth factor receptor expression, KRAS mutation status and anti-idiotypic response were also evaluated.

RESULTS

Sixty-three patients were included in the study. Thirty patients were entered into the control group, and thirty-three patients received the treatment with nimotuzumab. The antibody was very well tolerated. Objective response rate was 47.8 % (nimotuzumab group) and 15.4 % (control group). Disease control rate was 60.9 % (nimotuzumab group) and 26.9 % (control group). Response and disease control rate were higher in patients with EGFR overexpressing tumors.

CONCLUSION

Nimotuzumab plus chemoradiotherapy was safe and provided statistically significant objective response. A Phase III in patients with similar characteristics will be launched.

Lipid rafts: signaling and sorting platforms of cells and their roles in cancer

Lipid rafts are defined as microdomains within the lipid bilayer of cellular membranes that assemble subsets of transmembrane or glycosylphosphatidylinisotol-anchored proteins and lipids (cholesterol and sphingolipids) and experimentally resist extraction in cold detergent (detergent-resistant membrane). These highly dynamic raft domains are essential in signaling processes and also form sorting platforms for targeted protein traffic. Lipid rafts are involved in protein endocytosis that occurs via caveolae or flotillin-dependent pathways. Non-constitutive protein components of rafts fluctuate dramatically in cancer with impacts on cell proliferation, signaling, protein trafficking, adhesion and apoptosis. This article focuses on the identification of candidate cancer-associated biomarkers in carcinoma cells using state-of-the-art proteomics.

Analysis of differentially expressed proteins in oral squamous cell carcinoma by MALDI-TOF MS

PURPOSE

To explore the presence of differentially expressed proteins in OSCC for discrimination of tumour and normal mucosa to establish potential biomarkers and therapeutic targets.

EXPERIMENTAL DESIGN

Paired protein samples of 12 individuals (tongue cancer and non-cancerous mucosa) were separated by two-dimensional polyacrylamid gel electrophoresis. The protein patterns were compared pairwise and protein spots were quantified. We identified about 70 regulated proteins which we subsequently identified by MALDI-TOF mass spectrometry.

RESULTS

Cancerous and non-cancerous tissues could be most precisely distinguished by a panel of proteins. They include the heat shock proteins (hsp)70 and 90, keratins (ck) 5, 6, 13, 14, 16, 17 and 19, beta globin, alpha-2-actin, stratifin, tropomyosin, calreticulin precursor, beta-2-tubulin, galectin7, thioredoxin, involucrin, adenylyl-cyclase-associated protein, disulfide isomerase-associated protein, thyrosine 3-monooxygenase, MYL2 and the s100 calcium binding protein. MYL3, cardiac muscle alpha actin 1 proprotein and transferrin were under-represented in OSCC. Six biomarkers, ck6 und ck13, beta globin, alpha-2-actin, hsp70 and hsp90 discriminated best between cancerous and non-cancerous oral tissues. All over-expressed proteins were analysed by STRING-analysis to highlight experimentally determined and computationally predicted interactions between the proteins. Especially involucrin, hsp70, calreticulin precursor, stratifin, (ck) 5, 6, 14, 19, tyrosine 3-monooxygenase, beta-2-tubulin and disulfide isomerase associated protein showed multiple relations.

CONCLUSION

We identified six proteins which are differentially expressed in most OSCC compared to healthy tissues. Of those, by string analysis, multiple interaction partners are assumed for hsp70. This protein is supposed to be the most promising candidate as marker molecule and target for OSCC therapy.

Hyperthermia: malformations to chaperones

Hyperthermia has been known to induce malformations in numerous animal models as well being associated with human abnormalities. This was apparent particularly when the hyperthermia exposure was during the early stages of neural development. Although it was recognized relatively early that these exposures induced cell death, the specific molecular mechanism of how a brief heat exposure was translated in to specific cellular functions remains largely unknown. While our understanding of the events that govern how cells react to heat, or stresses in general, has increased, there is much that remains undiscovered. In this brief review, animal and clinical observations are outlined as are some of the scientific explorations that were undertaken to characterize, define, and better understand the morphological, biochemical, and molecular effects of hyperthermia on the developing embryo.

Personalized medicine in oncology: tailoring the right drug to the right patient

Despite advances in the management of many human cancers over the past few decades, improvements in survival are marginal, and the overall diagnosis and prognosis for cancer patients remain poor. Tailoring therapy to the individual patient has become a promising approach for maximizing efficacy and minimizing drug toxicity. Aided by major technological advances, the field of personalized medicine has become extremely active in the identification of predictive biomarkers that can guide treatment decisions and, ultimately, improve treatment outcomes. Genomics and proteomics have provided a means for molecular profiling that allows tailoring of therapy. Although implementing genomic and proteomic testing into clinical practice is still in its infancy, the rapid development of newer technologies and platforms provides hope for personalized medicine.