Diptoindonesin G is a middle domain HSP90 modulator for cancer treatment

Extracellular heat shock protein 90 alpha (eHsp90α)'s role in cancer progression and the development of therapeutic strategies

Heat shock protein 90 alpha (Hsp90α) is an abundantly expressed and evolutionarily conserved molecular chaperone. Hsp90α is the inducible Hsp90 isoform, and its expression and secretion extracellularly (eHsp90α) can be triggered in response to a variety of cellular stresses to protect/activate client proteins and to facilitate cellular adjustment to the stress. As a result, cancers often have high expression levels of intracellular and extracellular (plasma) Hsp90α, allowing them to support their oncogenesis and progression. In fact, (e)Hsp90α has been implicated in regulating processes such as cell signaling transduction, DNA repair, promotion of the Epithelial-to-Mesenchymal Transition (EMT), promotion of angiogenesis, immune response, and cell migration. Hsp90α levels have been correlated with cancer progression and severity in several cancers, indicating that it may be a useful biomarker or drug-target for cancer. To date, the development of intracellular Hsp90α-targeted therapies include standard N-terminal ATP-competitive inhibitors and allosteric regulators that bind to Hsp90α's middle or C-terminal domain. On-target toxicities and dosing complications as a result of Hsp90α inhibition has driven the development of eHsp90α-targeted therapies. Examples include anti-Hsp90α monoclonal antibodies and cell-impermeable Hsp90α small molecule inhibitors. This review aims to discuss the many roles Hsp90α plays in cancer progression with a focus on the current development of Hsp90α-targeted therapies.

An update on the status of HSP90 inhibitors in cancer clinical trials

The evolutionary conserved molecular chaperone heat shock protein 90 (HSP90) plays an indispensable role in tumorigenesis by stabilizing client oncoproteins. Although the functionality of HSP90 is tightly regulated, cancer cells exhibit a unique dependence on this chaperone, leading to its overexpression, which has been associated with poor prognosis in certain malignancies. While various strategies targeting heat shock proteins (HSPs) involved in carcinogenesis have been explored, only inhibition of HSP90 has consistently and effectively resulted in proteasomal degradation of its client proteins. To date, a total of 22 HSP90 inhibitors (HSP90i) have been tested in 186 cancer clinical trials, as reported by clinicaltrials.gov. Among these trials, 60 % have been completed, 10 % are currently active, and 30 % have been suspended, terminated, or withdrawn. HSP90 inhibitors (HSP90i) have been used as single agents or in combination with other drugs for the treatment of various cancer types in clinical trials. Notably, improved clinical outcomes have been observed when HSP90i are used in combination therapies, as they exhibit a synergistic antitumor effect. However, as single agents, HSP90i have shown limited clinical activity due to drug-related toxicity or therapy resistance. Recently, active trials conducted in Japan evaluating TAS-116 (pimitespib) have demonstrated promising results with low toxicity as monotherapy and in combination with the immune checkpoint inhibitor nivolumab. Exploratory biomarker analyses performed in various trials have demonstrated target engagement that suggests the potential for identifying patient populations that may respond favorably to the therapy. In this review, we discuss the advances made in the past 5 years regarding HSP90i and their implications in anticancer therapeutics. Our focus lies in evaluating drug efficacy, prognosis forecast, pharmacodynamic biomarkers, and clinical outcomes reported in published trials. Through this comprehensive review, we aim to shed light on the progress and potential of HSP90i as promising therapeutic agents in cancer treatment.

Visualization of breast cancer-related protein synthesis from the perspective of bibliometric analysis

Breast cancer, as a daunting global health threat, has driven an exponential growth in related research activity in recent decades. An area of research of paramount importance is protein synthesis, and the analysis of specific proteins inextricably linked to breast cancer. In this article, we undertake a bibliometric analysis of the literature on breast cancer and protein synthesis, aiming to provide crucial insights into this esoteric realm of investigation. Our approach was to scour the Web of Science database, between 2003 and 2022, for articles containing the keywords "breast cancer" and "protein synthesis" in their title, abstract, or keywords. We deployed bibliometric analysis software, exploring a range of measures such as publication output, citation counts, co-citation analysis, and keyword analysis. Our search yielded 2998 articles that met our inclusion criteria. The number of publications in this area has steadily increased, with a significant rise observed after 2003. Most of the articles were published in oncology or biology-related journals, with the most publications in Journal of Biological Chemistry, Cancer Research, Proceedings of the National Academy of Sciences of the United States of America, and Oncogene. Keyword analysis revealed that "breast cancer," "expression," "cancer," "protein," and "translation" were the most commonly researched topics. In conclusion, our bibliometric analysis of breast cancer and related protein synthesis literature underscores the burgeoning interest in this research. The focus of the research is primarily on the relationship between protein expression in breast cancer and the development and treatment of tumors. These studies have been instrumental in the diagnosis and treatment of breast cancer. Sustained research in this area will yield essential insights into the biology of breast cancer and the genesis of cutting-edge therapies.

Diptoindonesin G, a new Hsp90 drug

Hsp90 is a molecular chaperone that participates in protein folding, activation, and stabilization of substrate proteins. Since many diseases, including cancer, neurodegenerative diseases, and metabolic diseases, are caused by protein misfolding, drugs that inhibit Hsp90 are being pursued as potential targets for treatments. In the recent JBC Editor's Pick by Donahue et al., the authors show that diptoindonesin G is a new Hsp90 inhibitor that promotes degradation of the estrogen receptor, an Hsp90 client, without inducing the heat shock response.