The heat shock protein 90 inhibitor 17-AAG suppresses growth and induces apoptosis in human cholangiocarcinoma cells

Elucidating the causal association between gut microbiota and intrahepatic cholangiocarcinoma through Mendelian randomization analysis

Background

Intrahepatic cholangiocarcinoma (ICC) is an aggressive liver cancer with poor prognosis. The gut microbiota has been linked to ICC, but evidence for causality is lacking. Elucidating causal gut microbiota-ICC links could inform prevention and treatment strategies.

Materials and methods

We performed a bidirectional two-sample Mendelian randomization (MR) study to investigate causal associations between gut microbiota and ICC risk. Genome-wide significant single nucleotide polymorphisms (SNPs) associated with gut microbiota abundances were utilized as instrumental variables (IVs). Multiple methods assessed causality and sensitivity analyses evaluated result robustness. Bioinformatics analysis of genetic loci linked to gut microbiota and ICC examined potential mechanisms.

Results

Genetically predicted increases in Veillonellaceae, Alistipes, Enterobacteriales, and Firmicutes were suggestively associated with higher ICC risk, while increases in Anaerostipes, Paraprevotella, Parasutterella, and Verrucomicrobia appeared protective. Bioinformatics analysis revealed differentially expressed genes near gut microbiota-associated loci may influence ICC through regulating pathways and tumor immune microenvironment.

Conclusion

Our findings provide suggestive evidence for causal links between specific gut microbiota and ICC risk.

Enhancing the Efficiency of Mild-Temperature Photothermal Therapy for Cancer Assisting with Various Strategies

Conventional photothermal therapy (PTT) irradiates the tumor tissues by elevating the temperature above 48 °C to exert thermal ablation, killing tumor cells. However, thermal ablation during PTT harmfully damages the surrounding normal tissues, post-treatment inflammatory responses, rapid metastasis due to the short-term mass release of tumor-cellular contents, or other side effects. To circumvent this limitation, mild-temperature photothermal therapy (MTPTT) was introduced to replace PTT as it exerts its activity at a therapeutic temperature of 42-45 °C. However, the significantly low therapeutic effect comes due to the thermoresistance of cancer cells as MTPTT figures out some of the side-effects issues. Herein, our current review suggested the mechanism and various strategies for improving the efficacy of MTPTT. Especially, heat shock proteins (HSPs) are molecular chaperones overexpressed in tumor cells and implicated in several cellular heat shock responses. Therefore, we introduced some methods to inhibit activity, reduce expression levels, and hinder the function of HSPs during MTPTT treatment. Moreover, other strategies also were emphasized, including nucleus damage, energy inhibition, and autophagy mediation. In addition, some therapies, like radiotherapy, chemotherapy, photodynamic therapy, and immunotherapy, exhibited a significant synergistic effect to assist MTPTT. Our current review provides a basis for further studies and a new approach for the clinical application of MTPTT.

Overexpression of miR-27a predicts poor prognosis and promotes the progression in cholangiocarcinoma

The function of microRNA-27a (miR-27a) expression in cholangiocarcinoma (CCA) remains largely unclear; therefore, this study aimed to investigate the clinical significance and functional role of miR-27a in CCA. This study included 117 paired CCA tissues and adjacent normal tissues from CCA patients who received surgical resection. Reverse transcription-quantitative polymerase chain reaction was used to measure the expression levels of miR-27a in CCA tissues and cell lines. A Kaplan-Meier curve and Cox regression analysis were used to determine overall prognostic performance. The effects of miR-27a on cell proliferation, migration, and invasion were measured by CCK-8 and Transwell assays. The expression levels of miR-27a in patients with CCA and cell lines were higher than those in adjacent normal tissues and normal cells, respectively. Additionally, miR-27a levels were found to be associated with lymph node metastasis and TNM stages. The overall survival time of CCA patients with high miR-27a expression was poorer than that of those with low miR-27a expression. Furthermore, miR-27a overexpression promoted CCA cell proliferation, migration, and invasion, whereas knockdown of miR-27a suppressed cell proliferation, migration, and invasion. Taken together, these results suggest the potential usefulness of miR-27a in the prognosis and progression of CCA.

Spotlight on 17-AAG as an Hsp90 inhibitor for molecular targeted cancer treatment

Hsp90 is a ubiquitous chaperone with important roles in the organization and maturation of client proteins that are involved in the progression and survival of cancer cells. Multiple oncogenic pathways can be affected by inhibition of Hsp90 function through degradation of its client proteins. That makes Hsp90 a therapeutic target for cancer treatment. 17-allylamino-17-demethoxy-geldanamycin (17-AAG) is a potent Hsp90 inhibitor that binds to Hsp90 and inhibits its chaperoning function, which results in the degradation of Hsp90's client proteins. There have been several preclinical studies of 17-AAG as a single agent or in combination with other anticancer agents for a wide range of human cancers. Data from various phases of clinical trials show that 17-AAG can be given safely at biologically active dosages with mild toxicity. Even though 17-AAG has suitable pharmacological potency, its low water solubility and high hepatotoxicity could significantly restrict its clinical use. Nanomaterials-based drug delivery carriers may overcome these drawbacks. In this paper, we review preclinical and clinical research on 17-AAG as a single agent and in combination with other anticancer agents. In addition, we highlight the potential of using nanocarriers and nanocombination therapy to improve therapeutic effects of 17-AAG.

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.

Survivin, a molecular target for therapeutic interventions in squamous cell carcinoma

Squamous cell carcinoma (SCC) is the most common cancer worldwide. The treatment of locally advanced disease generally requires various combinations of radiotherapy, surgery, and systemic therapy. Despite aggressive multimodal treatment, most of the patients relapse. Identification of molecules that sustain cancer cell growth and survival has made molecular targeting a feasible therapeutic strategy. Survivin is a member of the Inhibitor of Apoptosis Protein (IAP) family, which is overexpressed in most of the malignancies including SCC and totally absent in most of the normal tissues. This feature makes survivin an ideal target for cancer therapy. It orchestrates several important mechanisms to support cancer cell survival including inhibition of apoptosis and regulation of cell division. Overexpression of survivin in tumors is also associated with poor prognosis, aggressive tumor behavior, resistance to therapy, and high tumor recurrence. Various strategies have been developed to target survivin expression in cancer cells, and their effects on apoptosis induction and tumor growth attenuation have been demonstrated. In this review, we discuss recent advances in therapeutic potential of survivin in cancer treatment.

Hsp90: A New Player in DNA Repair?

Heat shock protein 90 (Hsp90) is an evolutionary conserved molecular chaperone that, together with Hsp70 and co-chaperones makes up the Hsp90 chaperone machinery, stabilizing and activating more than 200 proteins, involved in protein homeostasis (i.e., proteostasis), transcriptional regulation, chromatin remodeling, and DNA repair. Cells respond to DNA damage by activating complex DNA damage response (DDR) pathways that include: (i) cell cycle arrest; (ii) transcriptional and post-translational activation of a subset of genes, including those associated with DNA repair; and (iii) triggering of programmed cell death. The efficacy of the DDR pathways is influenced by the nuclear levels of DNA repair proteins, which are regulated by balancing between protein synthesis and degradation as well as by nuclear import and export. The inability to respond properly to either DNA damage or to DNA repair leads to genetic instability, which in turn may enhance the rate of cancer development. Multiple components of the DNA double strand breaks repair machinery, including BRCA1, BRCA2, CHK1, DNA-PKcs, FANCA, and the MRE11/RAD50/NBN complex, have been described to be client proteins of Hsp90, which acts as a regulator of the diverse DDR pathways. Inhibition of Hsp90 actions leads to the altered localization and stabilization of DDR proteins after DNA damage and may represent a cell-specific and tumor-selective radiosensibilizer. Here, the role of Hsp90-dependent molecular mechanisms involved in cancer onset and in the maintenance of the genome integrity is discussed and highlighted.

17-AAG suppresses growth and invasion of lung adenocarcinoma cells via regulation of the LATS1/YAP pathway

The large tumour suppressor 1 (LATS1) signalling network has been proved to be an essential regulator within the cell, participating in multiple cellular phenotypes. However, it is unclear concerning the clinical significance of LATS1 and the regulatory mechanisms of 17-Allylamino-17- demethoxygeldanamycin (17-AAG) in lung adenocarcinoma (LAC). The aim of the present study was to investigate the correlation of LATS1 and yes-associated protein (YAP) expression with clinicopathological characteristics in LAC patients, and the effects of 17-AAG on biological behaviours of LAC cells. Subcutaneous LAC tumour models were further established to observe the tumour growth in nude mice. The results showed that the positive expression of LATS1 was significantly lowered (26.7% versus 68.0%, P < 0.001), while that of YAP was elevated (76.0% versus 56.0%, P + 0.03) in LAC tissues compared to the adjacent non-cancerous tissues; LAST1 expression was negatively correlated with YAP expression (r + 0.432, P < 0.001) and lymphatic invasion of the tumour (P + 0.015). In addition, 17-AAG inhibited proliferation and invasion, and induced cell apoptosis and cycle arrest in LAC cells together with increased expression of E-cadherin and p-LATS1, and decreased expression of YAP and connective tissue growth factor. Tumour volumes and weight were much smaller in 17-AAG-treated groups than those in untreated group (P < 0.01). Taken together, our findings indicate that decreased expression of LATS1 is associated with lymphatic invasion of LAC, and 17-AAG suppresses growth and invasion of LAC cells via regulation of the LATS1/YAP pathway in vitro and in vivo, suggesting that we may provide a promising therapeutic strategy for the treatment of human LAC.

Antitumor activity of the combination of an HSP90 inhibitor and a PI3K/mTOR dual inhibitor against cholangiocarcinoma

The PI3K/Akt/mTOR pathway is overactivated and heat shock protein (HSP) 90 is overexpressed in common cancers. We hypothesized that targeting both pathways can kill intrahepatic cholangiocarcinoma (CCA) cells. HSP90 and PTEN protein expression was evaluated by immunohistochemical staining of samples from 78 patients with intrahepatic CCA. CCA cell lines and a thioacetamide (TAA)-induced CCA animal model were treated with NVP-AUY922 (an HSP90 inhibitor) and NVP-BEZ235 (a PI3K/mTOR inhibitor) alone or in combination.

Both HSP90 overexpression and loss of PTEN were poor prognostic factors in patients with intrahepatic CCA. The combination of the HSP90 inhibitor NVP-AUY922 and the PI3K/mTOR inhibitor NVP-BEZ235 was synergistic in inducing cell death in CCA cells. A combination of NVP-AUY922 and NVP-BEZ235 caused tumor regression in CCA rat animal model. This combination not only inhibited the PI3K/Akt/mTOR pathway but also induced ROS, which may exacerbate the vicious cycle of ER stress. Our data suggest simultaneous targeting of the PI3K/mTOR and HSP pathways for CCA treatment.

Pharmacological induction of the 70-kDa heat shock protein protects against brain injury

The 70-kDa heat shock protein (HSP70) is known to protect the brain from injury through multiple mechanisms. We investigated the effect of pharmacological HSP70 induction in experimental traumatic brain injury (TBI). 3-month-old male C57/B6 mice were given 17-N-allylamino-17-demethoxygeldanamycin (17-AAG) intraperitoneally (IP, 2 mg/kg) or intracerebroventricularly (ICV, 1 μg/kg) to determine whether HSP70 could be induced in the brain. Mice were subjected to TBI via cortical controlled impact, and were treated with 17-AAG (or vehicle) IP according to one of two treatment regimens: (1) 2 mg/kg at the time of injury, (2) a total of three doses (4 mg/kg) at 2 and 1d prior to TBI and again at the time of injury. Brains were assessed for HSP70 induction, hemorrhage volume at 3 d, and lesion size at 14 d post-injury. Immunohistochemistry showed that both IP and ICV administration of 17-AAG increased HSP70 expression primarily in microglia and in a few neurons by 24 h but not in astrocytes. 17-AAG induced HSP70 in injured brain tissue as early as 6 h, peaking at 48 h and largely subsiding by 72 h after IP injection. Both treatment groups showed decreased hemorrhage volume relative to untreated mice as well as improved neurobehavioral outcomes. These observations indicate that pharmacologic HSP70 induction may prove to be a promising treatment for TBI.