geldanamycin and Neoplasms

The histone lysine demethylase 4 (KDM4) family plays an important role in regulating gene transcription, DNA repair, and metabolism. The dysregulation of KDM4 functions is associated with many human disorders, including cancer, obesity, and cardiovascular diseases. Selective and potent KDM4 inhibitors may help not only to understand the role of KDM4 in these disorders but also to provide potential therapeutic opportunities. Here, we provide an overview of the field and discuss current status, challenges, and opportunities lying ahead in the development of KDM4-based anticancer therapeutics.

Topics: Enzyme Inhibitors; Histone Demethylases; Humans; Jumonji Domain-Containing Histone Demethylases; Neoplasms

The 90 kD heat shock proteins (Hsp90) are molecular chaperones that are responsible for the folding of select proteins, many of which are directly associated with cancer progression. Consequently, inhibition of the Hsp90 protein folding machinery results in a combinatorial attack on numerous oncogenic pathways. Seventeen small-molecule inhibitors of Hsp90 have entered clinical trials for the treatment of cancer, all of which bind the Hsp90 N-terminus and exhibit

Topics: Antineoplastic Agents; Cell Line, Tumor; Cell Proliferation; Gene Silencing; Heterocyclic Compounds, 4 or More Rings; HSP90 Heat-Shock Proteins; Humans; Models, Molecular; Molecular Conformation; Neoplasms; Protein Folding; Small Molecule Libraries; Structure-Activity Relationship; Substrate Specificity; Urinary Bladder Neoplasms

Twenty-six 17-phenylethylamine-modified geldanamycin derivatives were synthesized and evaluated for antiproliferation activity in human cancer cell lines, LNCaP and MDA-MB-231. Five derivatives (2j, 2q, 2v, 2x, and 2 y) showed excellent in vitro antitumor activities. Among them, compound 2 y was the most potent lead, with IC50 values of 0.27 ± 0.11 and 0.86 ± 0.23 μm for LNCaP and MDA-MB-231, respectively. In particular, compound 2 y was more active than its precursor geldanamycin against LNCap cells. Liver injury test in mice demonstrated that 2 y group showed no significant difference for serum alanine aminotransferase (ALT) activity versus vehicle control, indicating that 2 y was a promising antitumor candidate. Preliminary structure-activity relationship (SAR) and molecular dynamics (MD) simulations of this new series of geldanamycin derivatives were also investigated, suggesting a theoretical model of 17-phenylethylaminegeldanamycins binding to Hsp90.

Topics: Animals; Antineoplastic Agents; Benzoquinones; Cell Line, Tumor; Cell Proliferation; Drug Design; Drug Screening Assays, Antitumor; HSP90 Heat-Shock Proteins; Humans; Lactams, Macrocyclic; Male; Mice; Neoplasms; Structure-Activity Relationship

Heat shock protein 90 (Hsp90) facilitates the maturation of many newly synthesized and unfolded proteins (clients) via the Hsp90 chaperone cycle, in which Hsp90 forms a heteroprotein complex and relies upon cochaperones, immunophilins, etc., for assistance in client folding. Hsp90 inhibition has emerged as a strategy for anticancer therapies due to the involvement of clients in many oncogenic pathways. Inhibition of chaperone function results in client ubiquitinylation and degradation via the proteasome, ultimately leading to tumor digression. Small molecule inhibitors perturb ATPase activity at the N-terminus and include derivatives of the natural product geldanamycin. However, N-terminal inhibition also leads to induction of the pro-survival heat shock response (HSR), in which displacement of the Hsp90-bound transcription factor, heat shock factor-1, translocates to the nucleus and induces transcription of heat shock proteins, including Hsp90. An alternative strategy for Hsp90 inhibition is disruption of the Hsp90 heteroprotein complex. Disruption of the Hsp90 heteroprotein complex is an effective strategy to prevent client maturation without induction of the HSR. Cucurbitacin D, isolated from Cucurbita texana, and 3-epi-isocucurbitacin D prevented client maturation without induction of the HSR. Cucurbitacin D also disrupted interactions between Hsp90 and two cochaperones, Cdc37 and p23.

Topics: Benzoquinones; Cucurbitaceae; DNA-Binding Proteins; Heat Shock Transcription Factors; HSP90 Heat-Shock Proteins; Humans; Lactams, Macrocyclic; MCF-7 Cells; Molecular Chaperones; Molecular Structure; Neoplasms; Transcription Factors; Triterpenes

A novel series of macrocyclic ortho-aminobenzamide Hsp90 inhibitors is reported. In continuation of our research, heterocycle-containing tethers were explored with the intent to further improve potency and minimize hERG liabilities. This effort culminated in the discovery of compound 10, which efficiently suppressed proliferation of HCT116 and U87 cells. This compound showed prolonged Hsp90-inhibitory activity at least 24h post-administration consistent with elevated and prolonged exposure in the tumor. When studied in a xenograft model, the compound demonstrated significant suppression of tumor growth.

Topics: Amines; Animals; Benzamides; Benzoquinones; Biomarkers, Tumor; Cell Line, Tumor; Cell Proliferation; Drug Discovery; HSP90 Heat-Shock Proteins; Humans; Inhibitory Concentration 50; Lactams, Macrocyclic; Macrocyclic Compounds; Mice; Models, Molecular; Molecular Structure; Neoplasms; Xenograft Model Antitumor Assays

A series of mold metabolites of Ascomycetes, structurally belonging to the class of azaphilones, were found to inhibit the heat shock protein Hsp90. In particular, bulgarialactone B was tested for its binding to Hsp90 using surface plasmon resonance and limited proteolysis assays and for its effects on Hsp90 client proteins expression in a series of human tumor cell lines. This compound showed high affinity for Hsp90, interacting with the 90-280 region of the N-terminal domain and down-regulated the Hsp90 client proteins Raf-1, survivin, Cdk4, Akt, and EGFR. Bulgarialactone B and other natural azaphilones showed antiproliferative activity in a panel of human tumor cell lines; their conversion into semisynthetic derivatives by reaction with primary amines increased the antiproliferative activity. Preliminary results indicated in vivo activity of bulgarialactone B against an ascitic ovarian carcinoma xenograft, thus supporting the therapeutic potential of this novel series of Hsp90 inhibitors.

Topics: Animals; Antineoplastic Agents; Ascomycota; Benzopyrans; Cell Line, Tumor; Cell Proliferation; Female; HSP90 Heat-Shock Proteins; Humans; Mice; Mice, Nude; Neoplasms; Pigments, Biological