Asymmetric Hsp90 N domain SUMOylation recruits Aha1 and ATP-competitive inhibitors.

The stability and activity of numerous signaling proteins in both normal and cancer cells depends on the dimeric molecular chaperone heat shock protein 90 (Hsp90). Hsp90's function is coupled to ATP binding and hydrolysis and requires a series of conformational changes that are regulated by cochaperones and numerous posttranslational modifications (PTMs). SUMOylation is one of the least-understood Hsp90 PTMs. Here, we show that asymmetric SUMOylation of a conserved lysine residue in the N domain of both yeast (K178) and human (K191) Hsp90 facilitates both recruitment of the adenosine triphosphatase (ATPase)-activating cochaperone Aha1 and, unexpectedly, the binding of Hsp90 inhibitors, suggesting that these drugs associate preferentially with Hsp90 proteins that are actively engaged in the chaperone cycle. Importantly, cellular transformation is accompanied by elevated steady-state N domain SUMOylation, and increased Hsp90 SUMOylation sensitizes yeast and mammalian cells to Hsp90 inhibitors, providing a mechanism to explain the sensitivity of cancer cells to these drugs.

Health-related quality of life in Japanese patients with bladder cancer measured by a newly developed Japanese version of the Bladder Cancer Index.

INTRODUCTION: We validated a Japanese version of the Bladder Cancer Index (BCI) as a tool for measuring health-related quality of life (HRQOL) in bladder cancer patients treated with various surgical procedures. METHODS: The reliability and validity of the Japanese BCI were examined in 397 Japanese patients with bladder cancer via cross-sectional analysis. The patients simultaneously completed the Short Form (SF)-12, EQ-5D, and the Functional Assessment of Cancer Therapy-General and Bladder (FACT-G and FACT-BL). The differences in BCI subscales among various treatment groups were analyzed. RESULTS: This study involved 397 patients (301 males and 96 females), with a mean age of 70 years and a median disease duration of 29 months (IQR: 12-66 months). Of these patients, 221 underwent transurethral resection of a bladder tumor, and 176 patients underwent radical cystectomy (ileal conduit: 101 patients, ileal neobladder: 49, and ureterostomy: 26). Cronbach's alpha coefficient was ≥ 0.78 for all subscales, except the bowel bother subscale. Despite moderate correlations being detected between the function and bother score in urinary and bowel domains, the sexual function score was inversely correlated with the sexual bother score (r = - 0.19). A missing value percentage of > 15% was associated with old age (p < 0.05). The mean domain scores differed significantly among distinct clinically relevant treatment groups. CONCLUSIONS: Although revisions are needed to make it easier for elderly patients to comprehend, we confirmed the reliability and validity of the Japanese BCI. The Japanese BCI could be used for cross-cultural assessments of HRQOL in bladder cancer patients.

[The Development of the Preoperative Nomogram Predicting Major Perioperative Complications after Radical Cystectomy with Ileal Conduit or Orthotopic Neobladder].

Radical cystectomy (RC) is the gold standard for managing muscle-invasive and high-risknon-muscleinvasive bladder cancer, but is accompanied by non-negligible operative risk. The aim of this study is to identify preoperative variables to predict major perioperative complications after RC and to develop a nomogram using the cohort from multiple institutions in Japan. We retrospectively reviewed 668 patients who underwent open RC with ileal conduit or neobladder at Hokkaido University hospital and 20 affiliated institutions between 1997 and 2010. Complications occurring within 90 days of surgery were graded using modified Clavien classification system. We defined modified Clavien grade 3 or more as major complications and performed univariate and multivariate logistic regression analyses. Predictive accuracy of the nomogram was evaluated with the area under the receiver operating characteristics curve (AUC). A total of 528 men and 140 women were included in this study. There were a total of 160/668 patients (24%) with major perioperative complications. A multivariate model identified gender (OR : 1. 63, p=0. 04), cardiovascular comorbidity (OR : 1.48, p=0.03) and simultaneous nephroureterectomy (OR : 2.81, p=0. 01) as independent predictors. Using these 3 variables, a nomogram was developed with the AUC of 0.58. Predictive performance of our nomogram showed only fair performance ; but at least, we identified male, cardiovascular comorbidity and simultaneous nephroureterectomy as independent predictors of perioperative major complications.

Perioperative morbidity and mortality of octogenarians treated by radical cystectomy-a multi-institutional retrospective study in Japan.

Objective: To determine the characteristics of 90-day morbidity and mortality after radical cystectomy in Japanese octogenarians. Methods: A retrospective multi-institutional study. We reviewed the records of 834 patients treated by open radical cystectomy between 1997 and 2010. All complications within 90 days after surgery were sorted into the 11 categories proposed by the Memorial Sloan-Kettering Cancer Center and graded according to the modified Clavien-Dindo system. We compared the characteristics of complications between ≥80-year (n = 86) and <80-year (n = 748) groups. Multivariate regression models were used to determine the predictors of complications. Results: American Society of Anesthesiologists score III-IV was more frequent (14% vs. 6%, respectively, P < 0.0001), and ureterocutaneostomy was more frequently performed (30% vs. 21%, respectively, P = 0.0148) in the ≥80-year group compared with <80-year group. There were no significant differences in the rates of any complication, major (Grade 3-5) complication, or 90-day mortality between the two groups (≥80-year group: 70%, 21%, 3.5%, respectively, <80-year group: 68%, 22%, 2%, respectively). The ≥80-year group had fewer genitourinary complications (7% vs. 16%, respectively, P = 0.0131). Multivariate regression analyses revealed that bowel-using urinary diversion (P = 0.0031) and the operative time (P = 0.0269) were significant predictors of any grade of complications, and a male sex (P = 0.0167), annual cystectomy volume (P = 0.0284) and prior cardiovascular comorbidity (P = 0.0034) were significant predictors of major complications. Conclusions: In our experience, radical cystectomy in Japanese octogenarians caused similar perioperative comorbidities. Old age as a single criterion should not be used to abandon radical cystectomy; careful preoperative assessment is mandatory.

Laparoscopic resection of paraaortic/paracaval neurogenic tumors: surgical outcomes and technical tips.

BACKGROUND: Due to variations in location and size, laparoscopic surgery for paraaortic or paracaval neurogenic tumors is challenging. We evaluated the surgical outcomes, as well as surgical tips and tricks. METHODS: Between 2000 and 2015, 25 procedures were performed in 24 patients. One patient underwent second surgery due to the recurrence of paraganglioma. Data were collected on the tumor diameter, tumor location, perioperative outcomes, pathology, and last-known disease status. Regarding the operative procedures, we reviewed the operative charts or videos to identify surgical tips and tricks. RESULTS: The median tumor diameter was 5.0 cm (range 1.5-10). The tumor location was suprahilar in 10, hilar in 6, and infrahilar in 9 cases. Regarding the approach, a transperitoneal approach was selected in 24 cases and retroperitoneal approach in 1. The median operative time and blood loss were 208 min (range 73-513) and 10 mL (range 0-1020), respectively. No patient required blood transfusion or conversion to open surgery. Pathological examination revealed paraganglioma in 12, ganglioneuroma in 7, and schwannoma in 6 cases. At the last follow-up, 23 patients were free of disease, while one patient developed metastatic multiple recurrence of paraganglioma 54 months after the second laparoscopic surgery. A review of the surgical records revealed several tips and tricks, including taping the vena cava/renal vein (n = 2) being helpful for detaching a retrocaval tumor from these great vessels, or rotating the kidney to provide a favorable operative view of tumors behind the renal hilum (n = 2). In recent cases, 3D-CT was helpful for preoperative planning. CONCLUSIONS: Laparoscopic resection of paraaortic or paracaval neurogenic tumors is feasible in experienced hands. Surgeons should be familiar with detaching maneuvers around great vessels and the mobilization of adjacent organs. Careful preoperative planning is mandatory.

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

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.

[Giant Prostate Carcinoma : A Case Report and Long-Term Outcomes in Japanese Patients].

A 79-year-old male was referred to the Department of Gastroenterology in our hospital due to a large palpable abdominal mass, with the suspicion of a gastrointestinal stromal tumor. An abdominal computed tomographic (CT) scan revealed a huge mass of 270×208×144 mm which occupied the entire pelvic cavity. Since the specimens obtained by an endoscopic ultrasound-guided fine-needle aspiration via lower intestinal tract revealed a Gleason score 4＋4 prostate adenocarcinoma, he was then referred to our department. Prostate specific antigen (PSA) was elevated to 3,087 ng/ml, and positron emission tomography-CT revealed right obturator lymph node metastasis and bone metastasis of the left 5th rib. Degarelix was administered as an androgen deprivation therapy, and the PSA level had decreased to 62.4 ng/ml one month later. At the last follow-up, the PSA level was 0.67 ng/ml and the tumorsize had decreased to 88×83×110 mm. Next, we conducted a follow-up survey by mail of 20 reported Japanese cases of a giant prostate carcinoma, and data on 17 cases were available for analysis. In the total of 18 cases, including the present case, with a median follow-up time of 26 months, the 2-year overall survival rate was 85.7% for patients without metastasis, and 65.6% forthose with metastasis.

Prospective mapping of lymph node metastasis in Japanese patients undergoing radical cystectomy for bladder cancer: characteristics of micrometastasis.

OBJECTIVE: To investigate node-disease prevalence including micrometastases and its survival impact on bladder cancer patients. METHODS: A total of 60 patients participated in this study, in which extended lymph node dissection was carried out according to the prospective rule (below aortic bifurcation). Radical cystectomy and extended lymph node dissection were performed by open surgery (n = 23) or laparoscopically (n = 37). Perioperative, pathological and follow-up data were collected. Micrometastasis in lymph nodes was investigated by pan-cytokeratin immunohistochemistry. Recurrence-free survival was estimated with the Kaplan-Meier method. RESULTS: The median number of lymph nodes removed was 29 (range: 10-103) and there was no significant difference between the two groups (open group: median 30, laparoscopic group: median 29). Routine pathological examination revealed that 10 patients had lymph node metastases. Immunohistochemistry revealed micrometastases in four additional patients (pNmicro+), who had been diagnosed with pN0 on routine pathological examination. After excluding the three patients with pure nonurothelial carcinoma on the final pathology (small cell carcinoma: n = 2, adenocarcinoma: n = 1), 10 out of the 57 urothelial carcinoma patients (17.5%) had node metastasis, and an additional 4 out of the 47 pN0 patients (4/47, 8.5%) had micrometastasis. The 2-year recurrence-free survival rates divided by pN stage were 82.4% for pN0, 66.7% for pNmicro+ and 12.5% for pN+ (three-sample log-rank test, P < 0.0001). Three out of the four patients with pNmicro+ were disease free at the last follow-up. CONCLUSIONS: We confirmed under extended lymph node dissection that a substantial proportion of the patients had node metastasis (pN+: n = 10 and pNmicro+: n = 4), and the pN stage influenced patient survival. Our observations of micrometastasis yielded additional evidence for the potential survival benefit of extended lymphadenectomy by eliminating microdisease.

Diagnostic outcome of ureteroscopy in urothelial carcinoma of the upper urinary tract: Incidence of later cancer detection and its risk factors after the first examination.

BACKGROUND: To determine the incidence of later cancer detection and its risk factors after the first diagnostic ureteroscopy. METHODS: One hundred and sixty-six patients undergoing diagnostic ureteroscopy based on the suspicion of urothelial carcinoma of the upper urinary tract (UC of the UUT) between 1995 and 2012 were included. We examined the diagnostic outcome of the initial ureteroscopy. Thereafter, we collected follow-up data on patients who had not been diagnosed with UC of the UUT at the first examination, and evaluated the incidence of later cancer detection and its risk factors using Cox hazard models. RESULTS: Of the 166 patients, 76 (45.8%) were diagnosed with UC of the UUT at the first diagnostic ureteroscopy. The remaining 90 (54.2%) were diagnosed with other malignancies (n = 22), non-malignant disorders (n = 18), or without disorders (n = 50). Of these 90 patients, follow-up data were available in 65 patients (median: 41 months, range: 3-170). During the follow-up, carcinoma was detected in 6 patients (6/65, 9.2%) at a median of 43.5 months (range: 10-59). Episodes of gross hematuria (p = 0.0048) and abnormal cytological findings (p = 0.0335) during the follow-up and a male sex (p = 0.0316) were adverse risk factors. CONCLUSION: Later cancer detection of UC of the UUT was not uncommon after the first examination. The risk analysis revealed the aforementioned characteristics.

Five-point Likert scaling on MRI predicts clinically significant prostate carcinoma.

BACKGROUND: To clarify the relationship between the probability of prostate cancer scaled using a 5-point Likert system and the biological characteristics of corresponding tumor foci. METHODS: The present study involved 44 patients undergoing 3.0-Tesla multiparametric MRI before laparoscopic radical prostatectomy. Tracing based on pathological and MRI findings was performed. The relationship between the probability of cancer scaled using the 5-point Likert system and the biological characteristics of corresponding tumor foci was evaluated. RESULTS: A total of 102 tumor foci were identified histologically from the 44 specimens. Of the 102 tumors, 55 were assigned a score based on MRI findings (score 1: n = 3; score 2: n = 3; score 3: n = 16; score 4: n = 11 score 5: n = 22), while 47 were not pointed out on MRI. The tracing study revealed that the proportion of >0.5 cm(3) tumors increased according to the upgrade of Likert scores (score 1 or 2: 33%; score 3: 68.8%; score 4 or 5: 90.9%, χ(2) test, p < 0.0001). The proportion with a Gleason score >7 also increased from scale 2 to scale 5 (scale 2: 0%; scale 3: 56.3%; scale 4: 72.7%; 5: 90.9%, χ(2) test, p = 0.0001). On using score 3 or higher as the threshold of cancer detection on MRI, the detection rate markedly improved if the tumor volume exceeded 0.5 cm(3) (<0.2 cm(3): 10.3%; 0.2-0.5 cm(3): 25%; 0.5-1.0 cm(3): 66.7%; 1.0 < cm(3): 92.1%). CONCLUSIONS: Each Likert scale favobably reflected the corresponding tumor's volume and Gleason score. Our observations show that "score 3 or higher" could be a useful threshold to predict clinically significant carcinoma when considering treatment options.

[The significance of metastasectomy in patients with metastatic renal cell carcinoma].

We conducted a retrospective study to clarify the clinical significance of metastasectomy in patients with metastatic renal cell carcinoma (mRCC). Of 83 mRCC patients who were treated at our hospital between 2005 and 2010, 19 patients who underwent metastasectomy during the treatment course were the subjects of the present study. By the purpose and timing of metastasectomy, we classified the 19 patients into three groups : (1) patients who immediately underwent metastasectomy at diagnosis of metastasis (primary group), (2) patients who underwent resection of clinically problematic metastatic lesions for the relief of their symptoms (palliative group), and (3) patients who underwent complete resection of all metastatic lesions after sufficient systemic therapies (consolidation group). In the primary group (n=5), four patients had lung metastasis and one had metastases to limbs and the adrenal gland. Overall survival at 3 years was 100%. In the palliative group (n=4), 3 patients underwent resection of brain metastasis and one underwent resection of skin metastasis. The symptoms associated with metastasis clearly improved. In the consolidation group (n=10), the metastasized organ was the lung in 5 patients, pancreas in 4, and liver in one. Preoperative systemic therapy included sunitinib or sorafenib in 5 patients, interferon-α in 4, and S-1 in one. After metastasectomy, systemic therapies were discontinued in 9 patients, 4 of whom did not experience RCC recurrence, with a median follow-up of 35 months. Overall survival at 3 years was 60%. Metastasectomy would be a good treatment option in patients with mRCC.

Peri-operative morbidity and mortality related to radical cystectomy: a multi-institutional retrospective study in Japan.

UNLABELLED: What's known on the subject? and What does the study add? Radical cystectomy remains associated with comparatively high perioperative morbidity and mortality, despite improvements in surgical techniques and perioperative care. At present, most studies on the complications associated with open radical cystectomy were derived from Western academic high-volume centres, and data from Japan and other Asian countries were very limited. Using the modified Clavien grading system and 11 category grouping reported from MSKCC, we observed that 68% of patients experienced at least one complication within 90 days of surgery, and 17% of patients experienced major complications (90-day mortality rate = 2%), which were compatible with reports from Western high-volume centres. As far as we know, our report is the largest one regarding perioperative morbidity and mortality in Asian patients who underwent radical cystectomy. OBJECTIVE: To determine the type, incidence and severity of 90-day morbidity after radical cystectomy in our institution and our affiliated hospitals in accordance with a standard reporting methodology. At present, most studies on complications associated with open radical cystectomy are derived from Western academic high-volume centres and data from Japan and other Asian countries remain very limited. PATIENTS AND METHODS: The study comprised a retrospective multi-institutional study. The records were reviewed of 928 patients who underwent open radical cystectomy between 1997 and 2010. All complications within 90 days of surgery were categorized into 11 specific categories and graded in accordance with the modified Clavien system. Multivariate regression models were used to determine predictors of complications. RESULTS: At least one complication was observed in 635 (68%) patients and a major (grade 3-5) complication was observed in 156 (17%) patients. The most common complication categories were infectious (30%), gastrointestinal (26%), wound-related (21%) and genitourinary (15%). The 30-day mortality rate was 0.8% and the 90-day mortality rate was 2%. A multivariate regression model showed that previous cardiovascular comorbidity and type of urinary diversion (i.e. ileal conduit or neobladder) were significant factors for any and major complications. CONCLUSIONS: Surgical complication-related radical cystectomy is significant and both previous cardiovascular comorbidity and the type of urinary diversion were found to be significant factors for any and major complications. The 90-day mortality rate was 2%, which is compatible with reports from Western high-volume centres.

TRIM24 mediates ligand-dependent activation of androgen receptor and is repressed by a bromodomain-containing protein, BRD7, in prostate cancer cells.

The androgen receptor (AR) is a ligand-dependent transcription factor that belongs to the family of nuclear receptors, and its activity is regulated by numerous AR coregulators. AR plays an important role in prostate development and cancer. In this study, we found that TRIM24/transcriptional intermediary factor 1alpha (TIF1alpha), which is known as a ligand-dependent nuclear receptor co-regulator, interacts with AR and enhances transcriptional activity of AR by dihydrotestosterone in prostate cancer cells. We showed that TRIM24 functionally interacts with TIP60, which acts as a coactivator of AR and synergizes with TIP60 in the transactivation of AR. We also showed that TRIM24 binds to bromodomain containing 7 (BRD7), which can negatively regulate cell proliferation and growth. A luciferase assay indicated that BRD7 represses the AR transactivation activity upregulated by TRIM24. These findings indicate that TRIM24 regulates AR-mediated transcription in collaboration with TIP60 and BRD7.

Chemotherapy-Induced IL8 Upregulates MDR1/ABCB1 in Tumor Blood Vessels and Results in Unfavorable Outcome.

Tumor endothelial cells (TEC) lining tumor blood vessels actively contribute to tumor progression and metastasis. In addition to tumor cells, TEC may develop drug resistance during cancer treatment, allowing the tumor cells to survive chemotherapy and metastasize. We previously reported that TECs resist paclitaxel treatment via upregulation of ABCB1. However, whether TEC phenotypes are altered by anticancer drugs remains to be clarified. Here, we show that ABCB1 expression increases after chemotherapy in urothelial carcinoma cases. The ratio of ABCB1-positive TEC before and after first-line chemotherapy in urothelial carcinoma tissues (n = 66) was analyzed by ABCB1 and CD31 immunostaining. In 42 cases (64%), this ratio increased after first-line chemotherapy. Chemotherapy elevated ABCB1 expression in endothelial cells by increasing tumor IL8 secretion. In clinical cases, ABCB1 expression in TEC correlated with IL8 expression in tumor cells after first-line chemotherapy, leading to poor prognosis. In vivo, the ABCB1 inhibitor combined with paclitaxel reduced tumor growth and metastasis compared with paclitaxel alone. Chemotherapy is suggested to cause inflammatory changes in tumors, inducing ABCB1 expression in TEC and conferring drug resistance. Overall, these findings indicate that TEC can survive during chemotherapy and provide a gateway for cancer metastasis. Targeting ABCB1 in TEC represents a novel strategy to overcome cancer drug resistance. SIGNIFICANCE: These findings show that inhibition of ABCB1 in tumor endothelial cells may improve clinical outcome, where ABCB1 expression contributes to drug resistance and metastasis following first-line chemotherapy.

TRIM36 interacts with the kinetochore protein CENP-H and delays cell cycle progression.

The tripartite motif-containing protein (TRIM) family is defined by the presence of a common domain structure composed of a RING finger, a B-box, and a coiled-coil motif. TRIM family proteins are involved in a broad range of biological processes and, consistently, their alterations result in diverse pathological conditions such as genetic diseases, viral infection, and cancer development. In this study, we found by using yeast two-hybrid screening that TRIM36 has a ubiquitin ligase activity and interacts with centromere protein-H, one of the kinetochore proteins. We also found by immunofluorescence analysis that TRIM36 colocalizes with alpha-tubulin, one of the microtubule proteins. Moreover, we found that overexpression of TRIM36 decelerates the cell cycle and attenuates cell growth. These results indicate that TRIM36 is potentially associated with chromosome segregation and that an excess of TRIM36 may cause chromosomal instability.

Outcome of metastatic urothelial carcinoma treated by systemic chemotherapy: Prognostic factors based on real-world clinical practice in Japan.

AIM: To clarify prognostic factors of metatstatic urothelial carcinoma treated by systemic chemotherapy in real-world clinical practice in the Japanese population. MATERIALS AND METHODS: A total of 228 patients with metastatic urothelial carcinoma undergoing systemic chemotherapy between 2000 and 2013 were included in the present multi-institutional study. The gemcitabine plus cisplatin regimen was administered as first-line chemotherapy to 131 patients, whereas methotrexate, vinblastine, doxorubicin, and cisplatin or its modified regimen was given to 71 patients. Of the 228 patients, 119 received at least 2 different regimens and 22 underwent resection of metastases (metastasectomy). Multivariate survival analysis was performed using the Cox proportional hazards model. The characteristics included were age, sex, Eastern Cooperative Oncology Group performance status (PS), primary site, pathology of primary site, hemoglobin levels, lactate dehydrogenase levels, C-reactive protein levels, corrected calcium levels, estimated glomerular filtration rate levels, history of prior chemotherapy, metastatic sites, resection of primary site, number of metastatic organs, and metastasectomy. RESULTS: The median overall survival (OS) time was 17 months. On multivariate analysis, female sex, good Eastern Cooperative Oncology Group PS at presentation, hemoglobin level≥10g/dl, and single organ metastasis were significant independent predictors of prolonged OS. For the survival effect of metastasectomy, the median OS time of the 22 patients with metastasectomy was 53 months, which was significantly longer when compared with patients not undergoing metastasectomy (15mo). After adjustment for the 4 aforementioned prognostic factors, metastasectomy still remained significant (hazard ratio: 0.364, P = 0.0008). CONCLUSIONS: Female sex, more favorable PS at presentation, hemoglobin level>10g/dl, and single organ metastasis were favorable prognostic factors. In addition, metastasectomy was associated with long-term disease control.

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.

Combined inhibition of Wee1 and Hsp90 activates intrinsic apoptosis in cancer cells.

Heat shock protein 90 (Hsp90) is an essential, evolutionarily conserved molecular chaperone. Cancer cells rely on Hsp90 to chaperone mutated and/or activated oncoproteins, and its involvement in numerous signaling pathways makes it an attractive target for drug development. Surprisingly, however, the impact of Hsp90 inhibitors on cancer cells is frequently cytostatic in nature, and efforts to enhance the antitumor activity of Hsp90 inhibitors in the clinic remain a significant challenge. In agreement with previous data obtained using Wee1 siRNA, we show that dual pharmacologic inhibition of Wee1 tyrosine kinase and Hsp90 causes cancer cells to undergo apoptosis in vitro and in vivo. Gene expression profiling revealed that induction of the intrinsic apoptotic pathway by this drug combination coincided with transcriptional downregulation of Survivin and Wee1, an outcome not seen in cells treated separately with either agent. At the translational level, expression of these two proteins, as well as activated Akt, was completely abrogated. These data support the hypothesis that Wee1 inhibition sensitizes cancer cells to Hsp90 inhibitors; they establish combined Wee1/Hsp90 inhibition as a novel therapeutic strategy; and they provide a mechanistic rationale for enhancing the pro-apoptotic activity of Hsp90 inhibitors.

Ubiquitin-conjugating enzyme UBE2Q2 suppresses cell proliferation and is down-regulated in recurrent head and neck cancer.

The ubiquitin-proteasome system has a crucial role in maintaining and regulating cellular homeostasis including carcinogenesis. UBE2Q2, also designated Ubci, is one of the ubiquitin-conjugating enzymes (E2), and it has been reported that mRNA of UBE2Q2 is highly expressed in human head and neck squamous cell carcinoma, particularly hypopharyngeal carcinoma. However, the involvement of UBE2Q2 in carcinogenesis has not been fully elucidated. Most cases of head and neck carcinoma are treated with cis-diamminedichloroplatinum (II; CDDP) or docetaxel, which are the most effective chemotherapeutic agents against squamous cell carcinomas. Nevertheless, some head and neck cancers develop resistance to these drugs, although the causes and mechanisms remain unknown. In this study, we found high expression levels of UBE2Q2 in human head and neck carcinoma cell lines and cancer tissues by using an anti-UBE2Q2 antibody at the protein level. We also found that the expression level of UBE2Q2 is decreased in cell lines and cancer tissues that have resistance to CDDP or docetaxel and in cancer tissues treated with CDDP or docetaxel. Furthermore, we found that overexpression of UBE2Q2 affects cell proliferation and anchorage-independent cell growth. These findings suggest that UBE2Q2 is a novel oncosuppressor that inhibits tumor growth and is related to the resistance to anticarcinoma agents and that UBE2Q2 likely functions as a novel diagnostic tool and a potentially therapeutic target for head and neck squamous cell carcinoma.