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UDP glucuronosyltransferase 1A expression levels determine the response of colorectal cancer cells to the heat shock protein 90 inhibitor ganetespib.

ABSTRACT: HSP90 inhibition represents a promising route to cancer therapy, taking advantage of cancer cell-inherent proteotoxic stress. The HSP90-inhibitor ganetespib showed benefit in advanced clinical trials. This raises the need to identify the molecular determinants of treatment response. We tested the efficacy of ganetespib on a series of colorectal cancer (CRC)-derived cell lines and correlated their sensitivities with comprehensive gene expression analysis. Notably, the drug concentration required for 50% growth inhibition (IC50) varied up to 70-fold (from 36 to 2500 nM) between different cell lines. Correlating cell line-specific IC50s with the corresponding gene expression patterns revealed a strong association between ganetespib resistance (IC50>500 nM) and high expression of the UDP glucuronosyltransferase 1A (UGT1A) gene cluster. Moreover, CRC tumor samples showed a comparable distribution of UGT1A expression levels. The members of the UGT1A gene family are known as drug-conjugating liver enzymes involved in drug excretion, but their function in tumor cells is hardly understood. Chemically unrelated HSP90 inhibitors, for example, 17-N-allylamino-17-demethoxygeldanamycin (17-AAG), did not show correlation of drug sensitivities with UGT1A levels, whereas the ganetespib-related compound NVP-AUY922 did. When the most ganetespib-resistant cell line, HT29, was treated with ganetespib, the levels of HSP90 clients were unaffected. However, HT29 cells became sensitized to the drug, and HSP90 client proteins were destabilized by ganetespib upon siRNA-mediated UGT1A knockdown. Conversely, the most ganetespib-sensitive cell lines HCT116 and SW480 became more tolerant toward ganetespib upon UGT1A overexpression. Mechanistically, ganetespib was rapidly glucuronidated and excreted in resistant but not in sensitive CRC lines. We conclude that CRC cell-expressed UGT1A inactivates ganetespib and other resorcinolic Hsp90 inhibitors by glucuronidation, which renders the drugs unable to inhibit Hsp90 and thereby abrogates their biological activity. UGT1A levels in tumor tissues may be a suitable predictive biomarker to stratify CRC patients for ganetespib treatment.

SUBMITTER: Landmann H

PROVIDER: S-EPMC4540199 | biostudies-literature | 2014 Sep

REPOSITORIES: biostudies-literature

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UDP glucuronosyltransferase 1A expression levels determine the response of colorectal cancer cells to the heat shock protein 90 inhibitor ganetespib.

Landmann H H Proia D A DA He S S Ogawa L S LS Kramer F F Beißbarth T T Grade M M Gaedcke J J Ghadimi M M Moll U U Dobbelstein M M

Cell death & disease 20140911

HSP90 inhibition represents a promising route to cancer therapy, taking advantage of cancer cell-inherent proteotoxic stress. The HSP90-inhibitor ganetespib showed benefit in advanced clinical trials. This raises the need to identify the molecular determinants of treatment response. We tested the efficacy of ganetespib on a series of colorectal cancer (CRC)-derived cell lines and correlated their sensitivities with comprehensive gene expression analysis. Notably, the drug concentration required ...[more]

PMID: 25210794

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Project description:Gastric cancer (GC) remains the fifth most common cancer worldwide. Heat-shock protein 90 (HSP90) has become an attractive therapeutic target in treating cancers, because of its abnormally high expression in cancers. Several successful cases of HSP90 inhibitors capable of inhibiting GC inspired us to try ganetespib, a clinically promising and actively investigated second-generation HSP90 inhibitor in GC treatment. In our study, we show that ganetespib markedly reduced the growth of MGC-803 and also significantly inhibited the growth of SGC-7901 and MKN-28 in a dose-dependent manner. It induced G2/M cell-cycle arrest and apoptosis in all three cell lines, together with the related markers affected significantly. Mechanistically, ganetespib caused pronounced decrease of expression of classic HSP90 client proteins. Specifically, it greatly affected epidermal growth factor receptor (EGFR) signaling cascades by markedly decreasing the levels of total EGFR and EGFR on cell membranes. EGFR knockdown also induced cell-cycle arrest and apoptosis accompanied with a decrease of several EGFR downstream proteins. These results strongly support that EGFR signaling greatly contributes to the ganetespib inhibitory effects. Besides, we found that the responses of GC cell lines to ganetespib correlated well with their EGFR expression levels: MGC-803, as well as AGS and BGC-803, with higher EGFR expression responded to ganetespib better, whereas SGC-7901 and MKN-28 with lower EGFR levels were much less sensitive to ganetespib. Although SGC-7901 and MKN-28 were not very sensitive to ganetespib, ganetespib worked synergistically with radiation and cisplatin in killing them. Importantly, ganetespib significantly inhibited the growth of xenograft tumors in vivo as a single agent or in combination with cisplatin. Results of hematoxylin/eosin staining, TUNEL (terminal deoxynucleotidyl transferase dUTP nick-end labeling) assays, and immunohistochemistry staining of phosphorylated cyclin-dependent kinase 1 (pCDK1), EGFR and Ki-67 revealed significant differences in ganetespib-treated tumors. Collectively, our data suggest that ganetespib, as a new potent treatment option, can be used for the molecularly targeted therapy of GC patients according to their expression profiles of EGFR.

Project description:Heat shock protein (Hsp) 90 is a key component of the super-chaperone complex that maintains functionally active conformation of various client proteins. Many of these client proteins regulate important nodal points in multiple signalling pathways that promote cancer cell growth and survival. Inhibitors of Hsp90, therefore, have the potential of functioning as anti-cancer agents with pleiotropic effects. Identification of novel Hsp90 inhibitors with more favourable pharmacological properties is a priority in cancer therapy. To achieve this goal, we screened a compound library using a biochemical assay based on refolding of denatured firefly luciferase. The assay revealed high sensitivity, reliability and reproducibility with a Z-factor of 0.81 ± 0.17. Six Hsp90 inhibitory compounds identified by this screening with IC50 values between 1.0 and 6 ?M were further characterised for anti-proliferative activity by Cell Titer-Blue Cell Viability Assay using multiple tumour cell lines. Of particular interest was ONO4140 with lowest GI50 values in three different cancer cell lines viz; DU-145, BT-474 and K562 cell lines. This study also revealed that short-term exposure of tumour cells with ONO4140 is sufficient to inhibit the catalytic activity of Hsp90, evaluated through disruption of Hsp90-p23 association by immunoprecipitation. This short term exposure appears to initiate events like degradation of Hsp90 client proteins such as ErbB2/Her-2 and Akt with concomitant inhibition of survival signalling leading to the apoptotic death of tumour cells as seen by western blotting and Caspase Glow-3,7 assay. The study also reveals that apoptosis following Hsp90 inhibition with ONO4140 occurs via Caspase9-Caspase3 intrinsic apoptotic pathway, a process that is likely triggered by inactivation of Akt. In conclusion, we have identified a novel class of synthetic compounds which show potent Hsp90 inhibitory action in preclinical studies. The discovery of this novel class of synthetic Hsp90 inhibitors with simple chemical backbone allows us to conduct further structural modifications to improve their potency and pharmacokinetic properties for use in cancer therapy.

Project description:BackgroundPolymorphism of genes encoding drug-metabolizing enzymes is known to play an important role in increased susceptibility of colorectal cancer. UGT1A gene locus has been suggested to define tissue-specific glucuronidation activity. Reduced capacity of glucuronidation is correlated with the development of colorectal cancer. Therefore, we sought to explore polymorphism of UGTlA gene in human colorectal cancer.MethodsCancerous and healthy tissues were obtained from selectedpatients. Blood samples were collected and UGTlA mRNA transcriptions were analyzed. Genomic DNA was prepared and UGTlA8 exon-1 sequences were amplified, visualized and purified. The extracted DNA was subcloned and sequenced. Two-tailed Fisher's exact test, Odds ratios (ORs), confidence interval (CIs) and Logistics Regression Analysis were used for statistical analysis.ResultsUGTlA mRNA expression was reduced in cancerous tissues compared with healthy tissues from the same patient . The UGTlA mRNA expression of healthy tissue in study patients was lower than control . The mRNA expression of cancerous tissue was down-regulated in UGTlAl, 1A3, 1A4, lA6, 1A9 and up-regulated in UGTlA8 and UGTlAl0 UGT1A5 and UGT1A7 were not expressed in colonic tissue of either group. The allele frequency of WT UGTlA8*1 was higher (p?=?0.000), frequency of UGTlA8*3 was lowered in control group (p?=?0.000). The expression of homozygous UGTlA8*1 was higher in control group (p?=?0.000). Higher frequency of both heterozygous UGTlA8*1/*3 and UGTlA8*2/*3 were found in study group (p?=?0.000; p?=?0.000). The occurrence of colorectal cancer was mainly related to the presence of polymorphic UGTlA8*3 alleles (p?=?0.000).ConclusionRegulation of human UGT1A genes is tissue-specific. Individual variation in polymorphic expressions of UGTlA gene locus was noted in all types of colonic tissue tested, whereas hepatic tissue expression was uniform. The high incidence of UGTlA8 polymorphism exists in colorectal cancer patients. UGTlA8*1 allele is a protective factor and UGTlA8*3 allele is a risk factor.

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UDP glucuronosyltransferase 1A expression levels determine the response of colorectal cancer cells to the heat shock protein 90 inhibitor ganetespib.

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UDP glucuronosyltransferase 1A expression levels determine the response of colorectal cancer cells to the heat shock protein 90 inhibitor ganetespib.

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