The role of LIM and SH3 protein-1 in bladder cancer metastasis.

The LIM and SH3 protein-1 (LASP-1) is a multi-domain protein that is involved in several malignant cancers. The role of LASP-1 in malignant phenotypes including high invasive properties and unrestricted cell proliferation, remain to be elucidated. The present study reported the association of LASP-1 expression with bladder cancer malignancy and its role in cancer cell invasion and proliferation. The immunohistochemical analysis of the expression status of LASP-1 in radical cystectomy specimens from invasive bladder cancer patients revealed that the LASP-1-positive patients demonstrated a decreased survival rate compared with the LASP-1-negative patients. The expression level of LASP-1 was increased in invasive bladder cancer cell lines compared with the non-invasive bladder cancer cell lines. Invasive cancer cells form invadopodia, the filamentous actin-based membrane protrusions that are essential in cancer cell invasion. Knockdown of LASP-1 reduced the ability to form invadopodia, resulting in decreased invasive capacity of the LASP-1 knockdown cells. In addition, knockdown of LASP-1 reduced cell proliferation. These results suggest that LASP-1 is important in invadopodia formation and cell proliferation of bladder cancer cells, promoting the malignant properties and resulting in poor-prognosis.

The influence of serum uric acid on renal function in patients with calcium or uric acid stone: A population-based analysis.

OBJECTIVES: To determine the influence of serum uric acid (UA) levels on renal impairment in patients with UA stone. MATERIALS AND METHODS: We retrospectively analyzed 463 patients with calcium oxalate and/or calcium phosphate stones (CaOx/CaP), and 139 patients with UA stones. The subjects were divided into the serum UA-high (UA ≥ 7.0 mg/dL) or the UA-low group (UA < 7.0 mg/dL). The control group comprised 3082 community-dwelling individuals that were pair-matched according to age, sex, body mass index, comorbidities, hemoglobin, serum albumin, and serum UA using propensity score matching. We compared renal function between controls and patients with UA stone (analysis 1), and between patients with CaOx/CaP and with UA stone (analysis 2). Logistic regression analysis was used to evaluate the impact of the hyperuricemia on the development of stage 3 and 3B chronic kidney disease (CKD) (analysis 3). RESULTS: The renal function was significantly associated with serum UA levels in the controls and patients with CaOx/CaP and UA stones. In pair-matched subgroups, patients with UA stone had significantly lower renal function than the control subjects (analysis 1) and patients with CaOx/CaP stones (analysis 2) regardless of hyperuricemia. Multivariate logistic regression analysis revealed that patients with UA stone, CaOx/CaP, hyperuricemia, presence of cardiovascular disease, higher body mass index, older age and lower hemoglobin had significantly higher risk of stage 3 and 3B CKD (analysis 3). CONCLUSION: Patients with UA stones had significantly worse renal function than controls and CaOx/CaP patients regardless of hyperuricemia. Urolithiasis (CaOx/CaP and UA stone) and hyperuricemia had an association with impaired renal function. Our findings encourage clinicians to initiate intensive treatment and education approaches in patients with urolithiasis and/or hyperuricemia in order to prevent the progression of renal impairment.

Clinical relevance of aortic calcification in urolithiasis patients.

BACKGROUND: The aim of the present study is to investigate the clinical relevance of aortic calcification in urolithiasis patients. METHODS: Between January 2010 and September 2014, 1221 patients with urolithiasis were treated in Oyokyo Kidney Research Institute and Hirosaki University Hospital. Among these, 287 patients (Stone group) on whom adequate data were available were included in this retrospective study. We also selected 148 subjects with early stage (pT1N0M0) renal cell carcinoma from 607 renal cell carcinoma patients who underwent radical nephrectomy at Hirosaki University Hospital (Non-stone group) as control subjects. Validity of the Non-stone group was evaluated by comparison with pair-matched 296 volunteers from 1166 subjects who participated in the Iwaki Health Promotion Project in 2014. Thereafter, age, body mass index, aortic calcification index (ACI), renal function, serum uric acid concentrations, and comorbidities (diabetes, hypertension, or cardiovascular disease) were compared between the Non-stone and Stone groups. Independent factors for higher ACI and impaired renal function were assessed using multivariate logistic regression analysis. RESULTS: We confirmed relevance of Non-stone group patients as a control subject by comparing the pair-matched community-dwelling volunteers. Backgrounds of patients between the Non-stone and Stone groups were not significantly different except for the presence of hypertension in the Stone group. ACI was not significantly high in the Stone group compared with the Non-stone group. However, age-adjusted ACI was greater in the Stone group than the Non-stone group. Among urolithiasis patients, ACI was significantly higher in uric acid containing stone patients. The number of patients with stage 3B chronic kidney disease (CKD) was significantly higher in the Stone group than in the Non-stone group (12% vs. 4%, P = 0.008). Multivariate logistic regression analysis showed higher aortic calcification index (>13%), and being a stone former were independent factors for stage 3B CKD at the time of diagnosis. CONCLUSION: Aortic calcification and being a stone former had harmful influence on renal function. This study was registered as a clinical trial: UMIN: UMIN000022962.

Aortic calcification burden predicts deterioration of renal function after radical nephrectomy.

BACKGROUND: Radical nephrectomy for renal cell carcinoma (RCC) is a risk factor for the development of chronic kidney disease (CKD), and the possibility of postoperative deterioration of renal function must be considered before surgery. We investigated the contribution of the aortic calcification index (ACI) to the prediction of deterioration of renal function in patients undergoing radical nephrectomy. METHODS: Between January 1995 and December 2012, we performed 511 consecutive radical nephrectomies for patients with RCC. We retrospectively studied data from 109 patients who had regular postoperative follow-up of renal function for at least five years. The patients were divided into non-CKD and pre-CKD based on a preoperative estimated glomerular filtration rate (eGFR) of ≥60 mL/min/1.73 m2 or <60 mL/min/1.73 m2, respectively. The ACI was quantitatively measured by abdominal computed tomography before surgery. The patients in each group were stratified between low and high ACIs. Variables such as age, sex, comorbidities, and pre- and postoperative renal function were compared between patients with a low or high ACI in each group. Renal function deterioration-free interval rates were evaluated by Kaplan-Meier analysis. Factors independently associated with deterioration of renal function were determined using multivariate analysis. RESULTS: The median age, preoperative eGFR, and ACI in this cohort were 65 years, 68 mL/min/1.73 m2, and 8.3%, respectively. Higher ACI (≥8.3%) was significantly associated with eGFR decline in both non-CKD and pre-CKD groups. Renal function deterioration-free interval rates were significantly lower in the ACI-high than ACI-low strata in both of the non-CKD and pre-CKD groups. Multivariate analysis showed that higher ACI was an independent risk factor for deterioration of renal function at 5 years after radical nephrectomy. CONCLUSIONS: Aortic calcification burden is a potential predictor of deterioration of renal function after radical nephrectomy. TRIAL REGISTRATION: This study was registered as a clinical trial: UMIN000023577.

A mechanism for evasion of CTL immunity by altered O-glycosylation of HLA class I.

Anti-tumour immunity by cytotoxic T-lymphocytes (CTLs) is essential to suppress tumour progression. Cancer cells that evade CTL immunity proliferate in the host, promoting metastasis, but mechanisms underlying this capacity remain unknown. Here we report that bladder cancer cells metastasized to lymph nodes evade CTL immunity by a new mechanism via altered glycosylation. CTLs normally recognize and kill cancer cells presenting antigenic peptides on human leukocyte antigen (HLA) class I. We show bladder cancer cells expressing the O-glycan processing enzyme, core2 ß-1,6-N-acetylglucosaminyltransferase (C2GnT) exhibit HLA class I O-glycan modified with poly-N-acetyllactosamine and are highly susceptible to CTL. In those cells, poly-N-acetyllactosamine on HLA class I O-glycan binds galectin-3 to form a cell-surface molecular lattice, enabling efficient cell-surface retention of HLA class I. In contrast, bladder cancer cells in which C2GnT is downregulated show decreased levels of poly-N-acetyllactosamine on HLA class I O-glycans, attenuating lattice formation and reducing the cell-surface half-life of HLA class I. These tumour cells present antigenic peptides less efficiently, thereby evading CTL lysis and facilitating metastasis.

Vimentin intermediate filament and plectin provide a scaffold for invadopodia, facilitating cancer cell invasion and extravasation for metastasis.

To investigate the molecular mechanisms of cancer metastasis, we have isolated a high-metastatic bladder cancer cell subpopulation from a low-metastatic cell line by using an in vivo selection system. Cells in the subpopulation showed a high ability to form invadopodia, the filamentous actin (F-actin)-based membrane protrusions that play an essential role in cancer cell invasion. Analysis of the gene expression profile revealed that the expression of an intermediate filament (IF) protein, vimentin and a cytoskeletal linker protein, plectin was up-regulated in the high-metastatic subpopulation compared with the low metastatic cell line. Here we report a novel role of vimentin IF and plectin in metastasis. In invasive bladder cancer cells, the vimentin IF-plectin-invadopodia F-actin link was formed. Disruption of this link severely impaired invadopodia formation, reducing the capacities of extracellular matrix degradation, transendothelial migration and metastasis. In addition, the vimentin assembly into the filaments was required for invadopodia formation. Our results suggest that plectin anchoring invadopodia to vimentin IF scaffolds and stabilizes invadopodia, which is a critical molecular process for cancer cell invasion and extravasation for metastasis.

Invadopodia are essential in transurothelial invasion during the muscle invasion of bladder cancer cells.

Muscle invasive bladder cancer is an aggressive type of epithelial tumor with a high rate of metastasis. For bladder cancer cells to reach the muscle layer, cells must invade through an urothelial cell monolayer (transurothelial invasion) and basement membrane. However, the process by which transurothelial invasion occurs has not been fully characterized. In this study we developed a novel method to evaluate the transurothelial invasion capacity and investigated its cellular and molecular processes using primary culture cells from bladder cancer patients. The analysis revealed that compared with the prognosis for patients with non­muscle invasive bladder cancer that of patients with muscle invasive bladder cancer was particularly poor due to metastatic recurrence. Cancer cells from patients with muscle invasive bladder cancer exhibited a higher invasive capacity through the urothelial cell monolayer compared with those from non­invasive bladder cancer patients. Furthermore, muscle invasive bladder cancer cells demonstrated a greater ability to form invadopodia, the filamentous actin­based membrane protrusions required for matrix degradation and invasion compared with non­invasive cells. Bladder cancer cell lines were established with reduced invadopodia formation by silencing the expression of cortactin, an essential component of invadopodia. The cortactin knockdown bladder cancer cells with reduced invadopodia formation demonstrated a markedly reduced ability to invade through the urothelial cell monolayer, indicating that invadopodia are essential for transurothelial invasion. The results indicate that invadopodia formation is required for muscle invasion of aggressive bladder cancer cells.

Extravasation during bladder cancer metastasis requires cortactin­mediated invadopodia formation.

Invasive cancer cells form the filamentous actin­based membrane protrusions known as invadopodia. Invadopodia are thought to play a critical role in cancer cell invasion and metastasis due to their ability to degrade the extracellular matrix. The present study assessed whether invadopodia formation is essential in extravasation of circulating bladder cancer cells and lung metastasis. To analyze the importance of invadopodia, bladder cancer cell lines with reduced invadopodia formation were established by silencing the expression of cortactin, an essential component of invadopodia, using cortactin short hairpin RNA. Bladder cancer cells with cortactin knockdown demonstrated a markedly decreased ability to form invadopodia, secrete matrix metalloproteinases and invade the extracellular matrix. In addition, the knockdown cells exhibited a reduced transendothelial invasion capacity and decreased formation of metastatic foci in the lungs. The present study demonstrated that bladder cancer cells with cortactin knockdown have a reduced capacity to extravasate into the lung from the circulation, due to the decreased invasive character of invadopodia. This suggests that invadopodia formation is a critical process for cancer cell extravasation.

Prognosis of elderly Japanese patients aged ≥80 years undergoing hemodialysis.

Although the number of elderly patients requiring dialysis has increased, data regarding the prognosis of elderly patients undergoing hemodialysis are limited. In the present study, prognosis in Japanese hemodialysis patients aged ≥80 years was evaluated. From January 1988 to July 2013, 1144 consecutive patients with end-stage renal disease required renal replacement therapy at our institution; of these, 141 were aged ≥80 years. These patients' charts were retrospectively reviewed for relevant clinical variables and survival time. The life expectancies table from the National Vital Statistics database was used, and prognostic factors were assessed by multivariate analysis. In total, 107 deaths (76%) were recorded during the study period. The median survival time and estimated life-shortening period in the patients were 2.6 years and -5.3 years, respectively. Eastern Cooperative Oncology Group Performance Status and hemoglobin level were revealed as prognostic factors in the multivariate analysis. Estimates of prognosis and prognostic factors may provide useful information for physicians as well as elderly patients with end-stage kidney disease.

Switching hemodialysis patients from sevelamer hydrochloride to bixalomer: a single-center, non-randomized analysis of efficacy and effects on gastrointestinal symptoms and metabolic acidosis.

BACKGROUND: Bixalomer (BXL) was developed to improve gastrointestinal symptoms and reduce constipation, relative to sevelamer hydrochloride, in hemodialysis patients. We prospectively evaluated the safety and effectiveness of switching maintenance dialysis patients from sevelamer hydrochloride to BXL. METHODS: Twenty-eight patients were switched from sevelamer hydrochloride to BXL (1:1 dose) from July to October 2012, whereas 84 randomly selected patients not treated with sevelamer hydrochloride were enrolled as a control group. The primary endpoint was improvement of gastrointestinal symptoms; secondary endpoints included improvement in metabolic acidosis, changes in blood biochemistry, and safety 12 weeks after the switch. We also surveyed patient satisfaction with switching to BXL 12 weeks after the switch. RESULTS: Before switching, symptoms of epigastric fullness were significantly worse in the switch than in the control group. Twelve weeks after the switch, reflux, epigastric fullness, and constipation had improved significantly in the switch group. Other factors, including stomach ache, diarrhea, and form of stool, did not change significantly. Blood gas analysis showed that metabolic acidosis was significantly improved by switching. Four patients (14%) experienced grade 1 adverse events, all of which improved immediately after stopping BXL. Major adverse events were diarrhea and abdominal discomfort. Mean satisfaction score was 3.1 ± 0.7, with 64% of patients reporting they were "neither satisfied nor dissatisfied" after switching. CONCLUSIONS: A switch from sevelamer hydrochloride to BXL improved symptoms of reflux, epigastric fullness, constipation, and metabolic acidosis in hemodialysis patients. TRIAL REGISTRATION: The study was registered as Clinical trial: (UMIN000011150).

In vivo selection of high-metastatic subline of bladder cancer cell and its characterization.

The majority of deaths associated with solid tumors are caused by tumor metastasis. To prevent metastasis, it is vital to understand its detailed process. In hematogenous metastasis of bladder cancer, some cancer cells disseminating into blood circulation extravasate into the lung tissues to form metastases. To study the molecular basis of the lung metastasis of bladder cancer, we employed an in vivo selection system that mimics hematogenous metastasis of bladder cancer on a low-metastatic bladder cancer cell line (KK-47). We have successfully isolated a high-metastatic bladder cancer subline, KK-47HM4, from KK-47 cells. We characterized KK-47HM4 in in vitro experimental systems. No significant difference in growth rate and susceptibility to NK cell attack between KK-47 and KK-47HM4 cells was observed. However, KK-47HM4 exhibited the higher capacities of Matrigel Matrix invasion and transendothelial invasion than KK-47. These results suggest that the extravasation of KK-47HM4 cells was enhanced among the multiple steps of the lung metastasis of bladder cancer. Our cDNA microarray analysis identified 67 genes whose expression was up- or downregulated in KK-47HM4 cells compared with KK-47 cells. This analysis data implied that one possible cause for enhanced extravasation of KK-47HM4 is its higher adhesion to extracellular matrix proteins. KK-47HM4 is the first bladder cancer subline with enhanced extravasation potential using the in vivo selection system. The information provided by our cDNA microarray analysis using KK-47HM4 will be useful for further investigation into the molecular basis of extravasation of cancer cells.

Serum N-glycan profiling predicts prognosis in patients undergoing hemodialysis.

BACKGROUND: The aim of this study is to evaluate the usefulness of serum N-glycan profiling for prognosis in hemodialysis patients. METHODS: Serum N-glycan analysis was performed in 100 hemodialysis patients in June 2008 using the glycoblotting method, which allows high-throughput, comprehensive, and quantitative N-glycan analysis. All patients were longitudinally followed up for 5 years. To evaluate the independent predictors for prognosis, patients' background, blood biochemistry, and N-glycans intensity were analyzed using Cox regression multivariate analysis. Selected N-glycans and independent factors were evaluated using the log-rank test with the Kaplan-Meier method to identify the predictive indicators for prognosis. Each patient was categorized according to the number of risk factors to evaluate the predictive potential of the risk criteria for prognosis. RESULTS: In total, 56 N-glycan types were identified in the hemodialysis patients. Cox regression multivariate analysis showed cardiovascular events, body mass index, maximum intima media thickness, and the serum N-glycan intensity of peak number 49 were predictive indicators for overall survival. Risk classification according to the number of independent risk factors revealed significantly poor survival by increasing the number of risk factors. CONCLUSIONS: Serum N-glycan profiling may have a potential to predict prognosis in patients undergoing hemodialysis.

Core2 O-glycan-expressing prostate cancer cells are resistant to NK cell immunity.

Core2 ß-1,6-N-acetylglucosaminyltransferase (C2GnT) forms an N-acetylglucosamine branch in the O-glycans (core2 O-glycans) of cell surface glycoproteins. We previously revealed that the expression of C2GnT is positively correlated with poor prognosis in prostate cancer patients. However, the detailed mechanisms underlying their poor prognosis remain unclear. In the current study, we report that the core2 O-glycans carried by the surface MUC1 glycoproteins of prostate cancer cells play an important role in the evasion of NK cell immunity. In C2GnT­expressing prostate cancer cells, the MUC1 core2 O-glycans are modified with poly-N-acetyllactosamine. MUC1 glycoproteins carrying poly-N-acetyllactosamine attenuated the interaction of the cancer cells with NK cells, resulting in decreased secretion of granzyme B by the NK cells. Poly­N­acetyllactosamine also interfered with the ability of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) to access the cancer cell surface. These effects of poly-N-acetyllactosamine on NK cells render C2GnT-expressing prostate cancer cells resistant to NK cell cytotoxicity. By contrast, C2GnT-deficient prostate cancer cells carrying a lower amount of poly-N-acetyllactosamine than the C2GnT-expressing prostate cancer cells were significantly more susceptible to NK cell cytotoxicity. Our results strongly suggest that C2GnT-expressing prostate cancer cells evade NK cell immunity and survive longer in the host blood circulation, thereby resulting in the promotion of prostate cancer metastasis.

Skin perfusion pressure is a prognostic factor in hemodialysis patients.

Peripheral arterial disease (PAD) is common in hemodialysis patients and predicts a poor prognosis. We conducted a prospective cohort study to identify risk factors for PAD including skin perfusion pressure (SPP) in hemodialysis patients. The cohort included 373 hemodialysis patients among 548 patients who received hemodialysis at Oyokyo Kidney Research Institute, Hirosaki, Japan from August 2008 to December 2010. The endpoints were lower limb survival (peripheral angioplasty or amputation events) and overall survival of 2 years. Our results showed that <70 mmHg SPP was a poor prognosis for the lower limb survival and overall survival. We also identified age, history of cardiovascular disease, presence of diabetes mellitus, smoking history, and SPP < 70 mmHg as independent risk factors for lower limb survival and overall survival. Then, we constructed risk criteria using the significantly independent risk factors. We can clearly stratify lower limb survival and overall survival of the hemodialysis patients into 3 groups. Although the observation period is short, we conclude that SPP value has the potential to be a risk factor that predicts both lower limb survival and the prognosis of hemodialysis patients.

MUC1 carrying core 2 O-glycans functions as a molecular shield against NK cell attack, promoting bladder tumor metastasis.

Core 2 ß-1,6-N-acetylglucosaminyltransferase (C2GnT) forms an N-acetylglucosamine branch in O-glycans (core 2 O-glycans) of cell surface glycoproteins. C2GnT-expressing bladder tumors acquire highly metastatic phenotypes by surviving longer in host blood circulation. However, the detailed mechanisms underlying this increased survival remain unclear. In this study, we report that the expression of C2GnT in bladder tumors positively correlates with tumor progression and that bladder tumor cell-surface mucin 1 (MUC1) carrying core 2 O-glycans plays an important role in the evasion from natural killer (NK) cell attack. In C2GnT-expressing bladder tumor cells, heavily core 2 O-glycosylated MUC1 carries poly-N-acetyllactosamine in its O-glycans and galectin-3 binds to MUC1 through this poly-N-acetyllactosamine. The binding of galectin-3 to poly-N-acetyllactosamine in MUC1 core 2 O-glycans attenuates the interaction of the tumor cells with NK cells and interferes with the access of tumor necrosis factor-related apoptosis-inducing ligand to the tumor cell surface. These effects of MUC1 carrying core 2 O-glycans on NK cell attack facilitate C2GnT-expressing tumor cells to evade NK cell immunity and survive longer in host blood circulation. We reveal that MUC1 carrying core 2 O-glycans thus functions as a molecular shield against NK cell attack, thereby promoting bladder tumor metastasis.

Effect of an Oral Adsorbent, AST-120, on Dialysis Initiation and Survival in Patients with Chronic Kidney Disease.

The oral adsorbent AST-120 has the potential to delay dialysis initiation and improve survival of patients on dialysis. We evaluated the effect of AST-120 on dialysis initiation and its potential to improve survival in patients with chronic kidney disease. The present retrospective pair-matched study included 560 patients, grouped according to whether or not they received AST-120 before dialysis (AST-120 and non-AST-120 groups). The cumulative dialysis initiation free rate and survival rate were compared by the Kaplan-Meier method. Multivariate analysis was used to determine the impact of AST-120 on dialysis initiation. Our results showed significant differences in the 12- and 24-month dialysis initiation free rate (P < 0.001), although no significant difference was observed in the survival rate between the two groups. In conclusion, AST-120 delays dialysis initiation in chronic kidney disease (CKD) patients but has no effect on survival. AST-120 is an effective therapy for delaying the progression of CKD.

Efficacy of SMART Stent Placement for Salvage Angioplasty in Hemodialysis Patients with Recurrent Vascular Access Stenosis.

Vascular access stenosis is a major complication in hemodialysis patients. We prospectively observed 50 patients in whom 50 nitinol shape-memory alloy-recoverable technology (SMART) stents were used as salvage therapy for recurrent peripheral venous stenosis. Twenty-five stents each were deployed in native arteriovenous fistula (AVF) and synthetic arteriovenous polyurethane graft (AVG) cases. Vascular access patency rates were calculated by Kaplan-Meier analysis. The primary patency rates in AVF versus AVG at 3, 6, and 12 months were 80.3% versus 75.6%, 64.9% versus 28.3%, and 32.3% versus 18.9%, respectively. The secondary patency rates in AVF versus AVG at 3, 6, and 12 months were 88.5% versus 75.5%, 82.6% versus 61.8%, and 74.4% versus 61.8%, respectively. Although there were no statistically significant difference in patency between AVF and AVG, AVG showed poor tendency in primary and secondary patency. The usefulness of SMART stents was limited in a short period of time in hemodialysis patients with recurrent vascular access stenosis.

Clearance and safety of the radiocontrast medium iopamidol in peritoneal dialysis patients.

Although the characteristics and safety of radiocontrast media in peritoneal dialysis (PD) patients are not yet well defined, their use in PD patients is considered generally safe. In this study, we evaluated clearance and adverse events of iopamidol in PD patients. We measured the iopamidol concentration in the plasma, dialysate, and urine of 11 patients. Iopamidol clearance from patient plasma was delayed with a half-life of 33.3 h, and the elimination ratio was 83.6% for 96 h. We retrospectively investigated adverse events occurring in a total of 50 stable PD patients who underwent a total of 64 angiographic computed tomography (CT) scans. In 64 angiographic CT scans, two cases of adverse events were observed. Our results suggest that iopamidol can be eliminated by regular PD and careful observation for adverse events are necessary for the safe use of radiocontrast media.

A novel strategy for evasion of NK cell immunity by tumours expressing core2 O-glycans.

The O-glycan branching enzyme, core2 ß-1,6-N-acetylglucosaminyltransferase (C2GnT), forms O-glycans containing an N-acetylglucosamine branch connected to N-acetylgalactosamine (core2 O-glycans) on cell-surface glycoproteins. Here, we report that upregulation of C2GnT is closely correlated with progression of bladder tumours and that C2GnT-expressing bladder tumours use a novel strategy to increase their metastatic potential. Our results showed that C2GnT-expressing bladder tumour cells are highly metastatic due to their high ability to evade NK cell immunity and revealed the molecular mechanism of the immune evasion by C2GnT expression. Engagement of an NK-activating receptor, NKG2D, by its tumour-associated ligand, Major histocompatibility complex class I-related chain A (MICA), is critical to tumour rejection by NK cells. In C2GnT-expressing bladder tumour cells, poly-N-acetyllactosamine was present on core2 O-glycans on MICA, and galectin-3 bound the NKG2D-binding site of MICA through this poly-N-acetyllactosamine. Galectin-3 reduced the affinity of MICA for NKG2D, thereby severely impairing NK cell activation and silencing the NK cells. This new mode of NK cell silencing promotes immune evasion of C2GnT-expressing bladder tumour cells, resulting in tumour metastasis.

Requirement for FBP17 in invadopodia formation by invasive bladder tumor cells.

PURPOSE: Invadopodia (protrusions of the plasma membrane formed by invasive tumor cells) have an essential role in bladder tumor invasion. To understand the process of bladder tumor invasion it is crucial to investigate the molecular mechanisms of invadopodia formation. We found that invasive bladder tumor cells express FBP17. In this study we examined the role of FBP17 in bladder tumor cell invadopodia formation and invasion. MATERIALS AND METHODS: We used the 3 bladder tumor cell lines YTS-1, T24 and RT4 (ATCC®), and primary culture of bladder tumors from patients. Cells were stained with phalloidin for invadopodia formation. FBP17 knockdown cells were tested for invadopodia formation and subjected to invasion assay using a Transwell® cell culture chamber. We also examined the role of the extended FER-CIP4 homology and Src homology 3 domains of FBP17 in invadopodia formation in FBP17 mutant constructs. RESULTS: Invadopodia formation was observed in invasive bladder tumor cells and FBP17 was localized to invadopodia in invasive cells. FBP17 knockdown decreased invadopodia formation in invasive cells to 13% to 14% (p <0.0005) and decreased their invasive capacity to 14% to 16% (p <0.001). The extended FER-CIP4 homology and Src homology 3 domains of FBP17 were necessary for invadopodia formation and invasion. CONCLUSIONS: Invadopodia formation requires membrane deformation activity and recruitment of dynamin-2 mediated by FBP17. FBP17 has a critical role in the process of bladder tumor cell invasion by mediating invadopodia formation.