Manabu Tatokoro

Molecular chaperone TRAP1 regulates a metabolic switch between mitochondrial respiration and aerobic glycolysis.

Significance TNF receptor-associated protein (TRAP1) is found predominantly in mitochondria. A possible direct impact of TRAP1 on mitochondrial metabolism remains unexplored. We used TRAP1-null cells and transient TRAP1 silencing/overexpression to show that TRAP1 regulates a metabolic switch between oxidative phosphorylation and aerobic glycolysis in immortalized mouse fibroblasts and in human tumor cells. TRAP1 deficiency promotes increased mitochondrial respiration, fatty acid oxidation, tricarboxylic acid cycle intermediates, ATP and reactive oxygen species, while concomitantly suppressing glucose metabolism. TRAP1 deficiency also results in strikingly enhanced cell motility and invasiveness. TRAP1 interaction with and regulation of mitochondrial c-Src provide a mechanistic basis for these phenotypes. TRAP1 (TNF receptor-associated protein), a member of the HSP90 chaperone family, is found predominantly in mitochondria. TRAP1 is broadly considered to be an anticancer molecular target. However, current inhibitors cannot distinguish between HSP90 and TRAP1, making their utility as probes of TRAP1-specific function questionable. Some cancers express less TRAP1 than do their normal tissue counterparts, suggesting that TRAP1 function in mitochondria of normal and transformed cells is more complex than previously appreciated. We have used TRAP1-null cells and transient TRAP1 silencing/overexpression to show that TRAP1 regulates a metabolic switch between oxidative phosphorylation and aerobic glycolysis in immortalized mouse fibroblasts and in human tumor cells. TRAP1-deficiency promotes an increase in mitochondrial respiration and fatty acid oxidation, and in cellular accumulation of tricarboxylic acid cycle intermediates, ATP and reactive oxygen species. At the same time, glucose metabolism is suppressed. TRAP1-deficient cells also display strikingly enhanced invasiveness. TRAP1 interaction with and regulation of mitochondrial c-Src provide a mechanistic basis for these phenotypes. Taken together with the observation that TRAP1 expression is inversely correlated with tumor grade in several cancers, these data suggest that, in some settings, this mitochondrial molecular chaperone may act as a tumor suppressor.

Impact of C-Reactive Protein Kinetics on Survival of Patients with Metastatic Renal Cell Carcinoma

BACKGROUND Pretreatment C-reactive protein (CRP) level has been shown to be prognostic for metastatic renal cell carcinoma (mRCC). OBJECTIVES To demonstrate that CRP would be a biomarker for mRCC, we evaluated the impact of CRP kinetics on survival. DESIGN, SETTING, AND PARTICIPANTS One hundred eight patients with mRCC were treated from 1994 to 2007 with a median follow-up period of 18 mo (interquartile range: 7-40 mo). INTERVENTION All patients underwent multimodal therapeutic intervention. MEASUREMENT Patients were divided into three groups according to CRP kinetics. Patients whose pretreatment CRP levels were <5mg/l, patients whose pretreatment CRP levels were >5mg/l and normalized (<5mg/l) at least one time during treatment, and patients whose pretreatment CRP levels were >5mg/l and never normalized were assigned to nonelevated, normalized, and non-normalized CRP groups, respectively. The prognostic impact of CRP kinetics and the correlation between normalized CRP period and overall survival period were determined. RESULTS AND LIMITATIONS In 61 of the 108 patients (56%), CRP levels were elevated at the diagnosis of mRCC. During treatment, CRP levels were normalized in 30 of 61 patients (49%), whereas CRP levels remained elevated in the remaining 31 patients. Overall survival rates were significantly different between nonelevated, normalized, and non-normalized CRP groups (p<0.001) with 2-yr survival rates of 69%, 55%, and 4%, respectively. In multivariate analysis, CRP kinetics was an independent significant factor for overall survival. Normalized CRP period was significantly correlated with overall survival period in 78 patients who died of disease. Since this is a small retrospective study on patients within the past era of immunotherapy, larger confirmatory studies in the current era of targeted therapy are needed. CONCLUSIONS CRP can be a novel, widely available biomarker for patients with mRCC.

Prognostic Impact of Postoperative C-Reactive Protein Level in Patients With Metastatic Renal Cell Carcinoma Undergoing Cytoreductive Nephrectomy

PURPOSE We explored the prognostic impact of C-reactive protein status in patients with metastatic renal cell carcinoma undergoing cytoreductive nephrectomy. MATERIALS AND METHODS The oncological outcome of 40 patients with metastatic renal cell carcinoma (TxpN1M0, TxNxM1) who underwent cytoreductive nephrectomy was analyzed. The C-reactive protein level was measured before and 1 month after cytoreductive nephrectomy. The normal value of C-reactive protein was considered less than 0.5 mg/dl. RESULTS During the median followup of 14 months 31 patients (78%) died of the disease. The preoperative C-reactive protein level was not increased in 17 of the 40 patients (nonelevated group). Of the remaining 23 patients with a preoperatively increased C-reactive protein level, after cytoreductive nephrectomy the C-reactive protein level normalized in 17 (normalized group). However, in the remaining 6 patients the C-reactive protein level did not normalize and remained high during followup (nonnormalized group). All of the patients in nonnormalized group died of the disease within 1 year. The overall survival rate of the nonnormalized group was significantly worse than that of the other 2 groups (p <0.0001). No significant difference was found in terms of overall survival rate between the normalized and nonelevated groups (p = 0.22). Multivariate analysis demonstrated that nonnormalized C-reactive protein (p <0.0001), absence of metastatectomy (p = 0.005), poorer performance status (p = 0.006) and bone metastases (p = 0.023) were independent factors for predicting poorer overall survival. CONCLUSIONS The current study indicated that C-reactive protein kinetics would predict the clinical course of patients with metastatic renal cell carcinoma who underwent cytoreductive nephrectomy. Larger confirmatory studies would be warranted to validate the current results.

Potential role of Hsp90 inhibitors in overcoming cisplatin resistance of bladder cancer-initiating cells

For metastatic bladder cancer patients, systemic cisplatin (CDDP)‐based combination chemotherapy is the first‐line choice of treatment. Although up to 70% of advanced bladder cancer patients initially show good tumor response to this form of combination chemotherapy, over 90% of good responders relapse and eventually die of the disease. According to the cancer stem cell theory, this phenomenon is attributable to the re‐growth of bladder cancer‐initiating cells (BCICs) that have survived chemotherapy. In this study, the authors have isolated BCICs from cultured human bladder cancer cells to analyze their sensitivity to CDDP and to investigate whether heat‐shock protein 90 (Hsp90) inhibitors potentiate the cytotoxicity of CDDP on BCICs. First, the authors have confirmed that a CD44+ subpopulation of 5637 cells met the requirements to be considered tumor‐initiating cells. These BCICs were more resistant to CDDP and exhibited more activity in the Akt and ERK oncogenic signaling pathways when compared with their CD44− counterparts. The Hsp90 inhibitor 17‐(dimethylaminoethylamino)‐17‐demethoxygeldanamycin (17‐DMAG), which simultaneously inactivated both Akt and ERK signaling at noncytocidal concentrations, synergistically potentiated the cytotoxicity of CDDP against BCICs by enhancing CDDP‐induced apoptosis in vitro. The potentiating effect of 17‐DMAG was more effective than a combination of the two inhibitors specific for the Akt and ERK pathways. Finally, the authors have confirmed that, though human BCIC xenografts exhibited resistance to a single administration of CDDP and the Hsp90 inhibitor 17‐(allylamino)‐17‐demethoxygeldanamycin (17‐AAG), 17‐AAG sensitized them to CDDP in a mouse model. These data encourage clinical trials of Hsp90 inhibitors as they may improve therapeutic outcomes of CDDP‐based combination chemotherapy against advanced bladder cancer.

The HSP90 Inhibitor Ganetespib Synergizes with the MET Kinase Inhibitor Crizotinib in both Crizotinib-Sensitive and -Resistant MET-Driven Tumor Models

The proto-oncogene MET is aberrantly activated via overexpression or mutation in numerous cancers, making it a prime anticancer molecular target. However, the clinical success of MET-directed tyrosine kinase inhibitors (TKI) has been limited due, in part, to mutations in the MET kinase domain that confer therapeutic resistance. Circumventing this problem remains a key challenge to improving durable responses in patients receiving MET-targeted therapy. MET is an HSP90-dependent kinase, and in this report we show that HSP90 preferentially interacts with and stabilizes activated MET, regardless of whether the activation is ligand-dependent or is a consequence of kinase domain mutation. In contrast, many MET-TKI show a preference for the inactive form of the kinase, and activating mutations in MET can confer resistance. Combining the HSP90 inhibitor ganetespib with the MET-TKI crizotinib achieves synergistic inhibition of MET, its downstream signaling pathways, and tumor growth in both TKI-sensitive and -resistant MET-driven tumor models. These data suggest that inclusion of an HSP90 inhibitor can partially restore TKI sensitivity to previously resistant MET mutants, and they provide the foundation for clinical evaluation of this therapeutic combination in patients with MET-driven cancers.

Heat shock protein 90 targeting therapy: state of the art and future perspective.

Heat shock protein 90 (Hsp90) is an ATP-dependent molecular chaperone that plays a role in stabilizing and activating more than 200 client proteins. It is required for the stability and function of numerous oncogenic signaling proteins that determine the hallmarks of cancer. Since the initial discovery of the first Hsp90 inhibitor in the 1970s, multiple phase II and III clinical trials of several Hsp90 inhibitors have been undertaken. This review provides an overview of the current status on clinical trials of Hsp90 inhibitors and future perspectives on novel anticancer strategies using Hsp90 inhibitors.

Low-dose Hsp90 inhibitors tumor-selectively sensitize bladder cancer cells to chemoradiotherapy

Although radical cystectomy with urinary diversion is the standard treatment for muscle-invasive bladder cancer (MIBC), loss of native bladder frequently impairs patients quality of life (QOL). Bladder-sparing approach incorporating chemoradiotherapy (CRT) improves QOL while not compromising survival outcomes in MIBC patients. In this approach, complete response to induction CRT is a prerequisite for bladder preservation and favorable oncological outcomes. We investigated a strategy to potentiate CRT response of bladder cancer cells by using Hsp90 inhibitors in preclinical models. Hsp90 inhibitors at low concentrations, which did not exert cytocidal effects but inactivated key anti-apoptotic proteins including erbB2, Akt, and NF-κB, efficiently sensitized bladder cancer cells (T24, 5637 and UM-UC-3 cells) to in vitro CRT by enhancing apoptosis. Importantly, the sensitizing effects were not observed in primarily cultured normal human urothelial cells. We also showed that CRT induces accumulation of nuclear phospho-Akt, which antagonizes apoptosis, and that Hsp90 inhibitors block the cellular process. Hsp90 inhibition sensitized bladder cancer cells to in vitro CRT more effectively than sole or combined inhibition of erbB2 and Akt. In mice UM-UC-3 tumor xenografts model, Hsp90 inhibitors successfully potentiated anti-tumor activity of CRT. These results encourage clinical trials of Hsp90 inhibitors to overcome CRT resistance in patients with MIBC.

Phase-II trial of combination treatment of interferon-α, cimetidine, cyclooxygenase-2 inhibitor and renin-angiotensin-system inhibitor (I-CCA therapy) for advanced renal cell carcinoma.

We have recently reported favorable responses to a combination treatment comprising cimetidine, a cyclooxygenase‐2 inhibitor and a renin‐angiotensin‐system inhibitor in metastatic renal cell carcinoma (RCC). In view of the potential synergistic effects of these three agents and interferon‐α (I‐CCA therapy), we conducted a phase‐II trial to examine the efficacy and toxicity of I‐CCA as first‐line treatment. Fifty‐one patients with advanced RCC received natural interferon‐α (3–6 million U thrice/week) and cimetidine (800 mg), cyclooxygenase‐2 inhibitor meloxicam (10 mg), and renin‐angiotensin‐system inhibitor candesartan (4 mg) or perindopril (4 mg) orally daily. Memorial Sloan–Kettering Cancer Center prognostic categories were favorable, intermediate and poor in 10 (20%), 31 (61%) and 10 (20%) patients, respectively. The primary end‐point was the objective response rate (ORR) and the secondary end‐points included clinical benefit, progression‐free survival (PFS), overall survival (OS) and safety. Median follow‐up was 19 months. Complete response (CR) was observed in four patients (8%) and partial response in seven (14%), yielding an ORR of 22%. None of the four patients who achieved CR relapsed during the 16‐ to 81‐month follow up. The ORR were 17% in the favorable‐ or intermediate‐risk group and 40% in the poor‐risk group. The other 24 patients (45%) had stable disease for at least 6 months, resulting in a clinical benefit rate of 67%. The median PFS and OS were 12 and 30 months, respectively. Grade 3/4 toxicities were never observed. The I‐CCA therapy, providing favorable responses and low toxicity profiles, is worthy of further consideration as a first‐line therapy for metastatic RCC. (Cancer Sci 2011; 102: 137–143)

Gasless laparoendoscopic single-port clampless sutureless partial nephrectomy for peripheral renal tumors: perioperative outcomes.

To describe the technical aspects of gasless laparoendoscopic single‐port clampless sutureless partial nephrectomy for peripheral renal tumors, and to evaluate its outcomes, including surgical, pathological, and short‐term oncological and functional outcomes.

Young Age as Favorable Prognostic Factor for Cancer-specific Survival in Localized Renal Cell Carcinoma

OBJECTIVES To evaluate the prognostic effect of age in patients with localized renal cell carcinoma (RCC) and investigate the incidence of Xp11 translocation RCC in young patients who developed recurrence. METHODS From 1990 to 2007, 2403 Japanese patients underwent nephrectomy for presumed RCC at 9 institutions. Of those, 1143 patients had localized RCC (Stage pT1-2N0M0). Their clinical data were retrospectively reviewed. In the present study, 131 patients (11%) were considered young (≤45 years at diagnosis). In the young patients with recurrence, the nephrectomy specimens were immunostained with TFE3 to determine the incidence of Xp11 translocation RCC. RESULTS During the median follow-up of 47 months, 3 cancer deaths (2.2%) occurred among young patients and 51 (5.0%) among older patients. The 5-year cancer-specific survival (CSS) rate was significantly better for the younger patients than for the older patients (P = .049). Multivariate analysis showed that age was significantly associated with CSS, as were the pathologic T stage, tumor grade, and symptoms at diagnosis. The hazard ratio of young age was 0.31 (95% confidence interval 0.077-0.87). The recurrence-free survival curves revealed no difference between these 2 groups. Of the 74 patients with recurrence, the CSS after recurrence was significantly better in the younger patients than in the older patients (P = .0010). Of the 8 young patients with recurrence, 4 had Xp11 translocation RCC, and 3 survived for >5 years after recurrence. CONCLUSIONS Compared with the older patients, the young patients with RCC had similar recurrence-free survival rates but better CSS rates. This might have been because significant numbers of the young patients had Xp11 translocation RCC.