Yoshihide Kawasaki

Ganglioside DSGb5, preferred ligand for Siglec-7, inhibits NK cell cytotoxicity against renal cell carcinoma cells

In renal cell carcinoma (RCC), the presence of higher gangliosides correlates with systematic metastasis. Disialosyl globopentaosylceramide (DSGb5) was identified previously as one of the major gangliosides from RCC tissues. Siglec-7 (sialic acid-binding Ig-like lectin-7), expressed on natural killer (NK) cells as an inhibitory receptor, has a striking preference for internally branched α2,6-linked disialic gangliosides such as DSGb5. To clarify the functional role of DSGb5 in RCC metastases, we have investigated whether DSGb5 expressed on RCC cells can modulate NK cell cytotoxicity in a Siglec-7-dependent manner. The binding activity of RCC cells to Siglec-7-Fc fusion protein was specifically inhibited by anti-DSGb5 monoclonal antibody and transfection of siRNA for ST6GalNAcVI (synthetase of DSGb5). These observations showed that Siglec-7-Fc fusion protein specifically bound to DSGb5 expressed on RCC cells. In contrast, the sialic acid-binding site of Siglec-7 on NK cells was masked by cis interactions with endogenous sialoconjugates at the cell surface, but it could be unmasked by sialidase treatment of the NK cells. Following sialidase treatment of NK cells, NK cell cytotoxicity against RCC cells with high DSGb5 expression was significantly decreased relative to cells with low DSGb5 expression. These findings indicate that such NK cell cytotoxicity against RCC cells could be inhibited by the interaction between Siglec-7 on effecter cells and DSGb5 on target cells. The results of the present study suggest that DSGb5 expressed on RCC cells can downregulate NK cell cytotoxicity in a DSGb5-Siglec-7-dependent manner and that RCC cells with DSGb5 create favorable circumstance for their own survival and metastases.

Is there a role for segmental adrenal venous sampling and adrenal sparing surgery in patients with primary aldosteronism

OBJECTIVE AND DESIGN Adrenal venous sampling (AVS) is critical to determine the subtype of primary aldosteronism (PA). Central AVS (C-AVS)--that is, the collection of effluents from bilateral adrenal central veins (CV)--sometimes does not allow differentiation between bilateral aldosterone-producing adenomas (APA) and idiopathic hyperaldosteronism. To establish the best treatment course, we have developed segmental AVS (S-AVS); that is, we collect effluents from the tributaries of CV to determine the intra-adrenal sources of aldosterone overproduction. We then evaluated the clinical utility of this novel approach in the diagnosis and treatment of PA. METHODS We performed C-AVS and/or S-AVS in 297 PA patients and assessed the accuracy of diagnosis based on the results of C-AVS (n=138, 46.5%) and S-AVS (n=159, 53.5%) by comparison with those of clinicopathological evaluation of resected specimens. RESULTS S-AVS demonstrated both elevated and attenuated secretion of aldosterone from APA and non-tumorous segments, respectively, in patients with bilateral APA and recurrent APA. These findings were completely confirmed by detailed histopathological examination after surgery. S-AVS, but not C-AVS, also served to identify APA located distal from the CV. CONCLUSIONS Compared to C-AVS, S-AVS served to identify APA in some patients, and its use should expand the pool of patients eligible for adrenal sparing surgery through the identification of unaffected segments, despite the fact that S-AVS requires more expertise and time. Especially, this new technique could enormously benefit patients with bilateral or recurrent APA because of the preservation of non-tumorous glandular tissue.

Laparoscopic simultaneous bilateral adrenalectomy: assessment of feasibility and potential indications.

Objective:  To report a single‐center experience with laparoscopic simultaneous bilateral adrenalectomy (LSBA) and to evaluate its safety, surgical outcomes, and potential indications of the procedure.

A case of bilateral aldosterone-producing adenomas differentiated by segmental adrenal venous sampling for bilateral adrenal sparing surgery

Primary aldosteronism due to unilateral aldosterone-producing adenoma (APA) is a surgically curable form of hypertension. Bilateral APA can also be surgically curable in theory but few successful cases can be found in the literature. It has been reported that even using successful adrenal venous sampling (AVS) via bilateral adrenal central veins, it is extremely difficult to differentiate bilateral APA from bilateral idiopathic hyperaldosteronism (IHA) harbouring computed tomography (CT)-detectable bilateral adrenocortical nodules. We report a case of bilateral APA diagnosed by segmental AVS (S-AVS) and blood sampling via intra-adrenal first-degree tributary veins to localize the sites of intra-adrenal hormone production. A 36-year-old man with marked long-standing hypertension was referred to us with a clinical diagnosis of bilateral APA. He had typical clinical and laboratory profiles of marked hypertension, hypokalaemia, elevated plasma aldosterone concentration (PAC) of 45.1 ng dl−1 and aldosterone renin activity ratio of 90.2 (ng dl−1 per ng ml−1 h−1), which was still high after 50 mg-captopril loading. CT revealed bilateral adrenocortical tumours of 10 and 12 mm in diameter on the right and left sides, respectively. S-AVS confirmed excess aldosterone secretion from a tumour segment vein and suppressed secretion from a non-tumour segment vein bilaterally, leading to the diagnosis of bilateral APA. The patient underwent simultaneous bilateral sparing adrenalectomy. Histopathological analysis of the resected adrenals together with decreased blood pressure and PAC of 5.2 ng dl−1 confirmed the removal of bilateral APA. S-AVS was reliable to differentiate bilateral APA from IHA by direct evaluation of intra-adrenal hormone production.

Ganglioside, Disialosyl Globopentaosylceramide (DSGb5), Enhances the Migration of Renal Cell Carcinoma Cells

About one third of renal cell carcinoma (RCC) patients exhibit metastasis upon initial presentation. However, the molecular basis for RCC metastasis is not fully understood. A ganglioside, disialosyl globopentaosylceramide (DSGb5), was originally isolated from RCC tissue extracts, and its expression is correlated with RCC metastatic potential. DSGb5 is synthesized by GalNAc α2,6-sialyltransferase VI (ST6GalNAcVI) and is expressed on the surface of RCC cells. Importantly, DSGb5 binds to sialic acid-binding Ig-like lectin-7 (Siglec-7) expressed on natural killer (NK) cells, thereby inhibiting NK-cell cytotoxicity. However, the role of DSGb5 in RCC progression remains obscure. To address this issue, we used ACHN cells derived from malignant pleural effusion of a patient with metastatic RCC. Using the limiting dilution method, we isolated three independent clones with different DSGb5 expression levels. Comparison of these clones indicated that the cloned cells with high DSGb5 expression levels exhibited greater migration potential, compared to the clone with low DSGb5 expression levels. In contrast, DSGb5 expression levels exerted no significant effect on cell proliferation. We then established the ACHN-derived cell lines that stably expressed siRNA against ST6GalNAcVI mRNA or control siRNA. Importantly, the ST6GalNAcVI-knockdown cells expressed low levels of DSGb5. We thus demonstrated the significantly decreased migration potential of the ST6GalNAcVI-knockdown cells with low DSGb5 expression levels, compared to the control siRNA-transfected cells expressing high DSGb5 levels, but no significant difference in the cell proliferation. Thus, DSGb5 expression may ensure the migration of RCC cells. We propose that DSGb5 expressed on RCC cells may determine their metastatic capability.

Severe toxicity induced by accumulation of active sunitinib metabolite in a Japanese patient with renal cell carcinoma: a case report

BackgroundSunitinib is a multi-targeted tyrosine kinase inhibitor that is approved for treatment of renal cell carcinoma as an oral anticancer drug. Therapeutic drug monitoring of total sunitinib (sunitinib and N-desethyl sunitinib) is used in our hospital to improve therapeutic efficacy, while preventing adverse effects. Here, we report the first case of a patient with metastatic renal cell carcinoma undergoing hemodialysis and presenting severe adverse events induced by the accumulation of N-desethyl sunitinib.Case presentationA 60-year-old Japanese man was diagnosed with metastatic renal cell carcinoma requiring hemodialysis. On day 26 of the first cycle of sunitinib therapy, our patient presented grade 3 thrombocytopenia and leukopenia, which required interruption of therapy although the plasma levels of total sunitinib in the patient were less than the effective concentration of 50 ng/mL. The elimination half-life of sunitinib was normal at 50.8 hours, but that of N-desethyl sunitinib was an extended 211.4 hours. Moreover, the N-desethyl sunitinib/sunitinib trough level ratio was higher than 1.0. We attribute our patient’s severe adverse events to the excessive accumulation of N-desethyl sunitinib owing to its delayed excretion. Although the reason for the delayed excretion of N-desethyl sunitinib in this patient was unknown, it may have been caused by genetic polymorphisms related to the pharmacokinetics of sunitinib rather than the hemodialysis. In this case, the patient was homozygous for the ABCG2 421C allele, but was capable of potentially harboring polymorphisms in other genes, such as ABCB1, an efflux pump of sunitinib. In addition, even though there is no clear evidence, urinary excretion of the metabolic products of N-desethyl sunitinib could be inhibited by the interaction of transporters such as the organic ion transporter.ConclusionsThe monitoring of not only total sunitinib concentration but also N-desethyl sunitinib concentration and their elimination half-lives during sunitinib therapy is recommended to avoid critical adverse events.

Evaluating estimated glomerular filtration rates of creatinine and cystatin C for male patients with chronic spinal cord injury

Study designRetrospective studyObjectivesTo compare the accuracy of estimated serum creatinine (Cre)–based glomerular filtration rates (eGFRcre) and serum cystatin C (CysC)–based eGFR (eGFRcys) for determining renal function in patients with spinal cord injury (SCI).SettingDepartment of Urology, Tohoku Rosai Hospital, JapanMethodsMale patients with SCI for longer than 5 years after injury were eligible for inclusion in this study. eGFRcre and eGFRcys were calculated using the following formulas: eGFRcre = 194 × Cre-1.094 × age-0.287; eGFRcys = (104 × CysC-0.1019 × 0.996age) − 8. The eGFRcre/eGFRcys ratio between 0.8 and 1.2 was considered to be equal, and a relationship between them was investigated. Demographic data, degree of spinal cord damage, management of bladder emptying, post-injury period, and ambulatory status were evaluated.ResultsA total of 115 male patients were included. eGFRcre overestimated renal function in 87 (76%) patients with SCI compared with eGFRcys. On univariate analysis, renal function by eGFRcre was overestimated in patients with an eGFRcre of more than 60 ml min-1 per 1.73 m2 (P < 0.001), in non-ambulatory patients (P < 0.001) and, in patients with complete paralysis (P < 0.001). On multivariate analysis, an eGFRcre of more than 60 ml min-1 per 1.73 m2 (P < 0.001), non-ambulatory status (P < 0.001), complete paralysis (P = 0.17), and age (P < 0.001) were independent factors for overestimated renal function by eGFRcre.ConclusionseGFRcre overestimates renal function compared with eGFRcys. eGFRcys is beneficial, particularly in patients with an eGFRcre of more than 60 ml min-1 per 1.73 m2, in non-ambulatory patients, and in older patients with SCI.

Simultaneous analysis of oral anticancer drugs for renal cell carcinoma in human plasma using liquid chromatography/electrospray ionization tandem mass spectrometry

An analytical method using high-performance liquid chromatography/electrospray ionization tandem mass spectrometry has been developed and validated for simultaneous measurement of four tyrosine kinase inhibitors used for renal cell carcinoma and their metabolites in human plasma. Despite their similar structures, it is difficult to measure plasma levels of these compounds simultaneously using optimal MS parameters for each compound because a quantitative range exceeding 50,000-fold is required. To overcome this problem, we used a linear range shift technique using in-source collision-induced dissociation. Linearity ranges of sorafenib, sorafenib N-oxide, sunitinib, N-desethyl sunitinib, axitinib and pazopanib were 100-10,000, 10-1,000, 1-100, 1-100, 1-100 and 500-50,000 ng/mL, respectively. The intra- and inter-day precision and accuracy were high, and coefficients of variation and relative error were <10.3% and within ±11.8%, respectively. The matrix effects of all analytes ranged from 87.7 to 114.8%. Extraction recoveries and overall recoveries showed small extraction loss (<15.0%) for all analytes. Moreover, all cancer patient samples used in this study were successfully quantified and fell within the linear range of measurement. Therefore, this novel analytical system using in-source collision-induced dissociation has sufficient performance to measure plasma concentrations of these four tyrosine kinase inhibitors and their metabolites for therapeutic drug monitoring.

Clinical predictors of the estimated glomerular filtration rate 1 year after radical nephrectomy in Japanese patients

Purpose To evaluate renal function 1 year after radical nephrectomy (RN) for renal cell carcinoma, the preoperative predictors of postnephrectomy renal function were investigated by sex, and equations to predict the estimated glomerular filtration rate (eGFR) 1 year after RN were developed. Materials and Methods A total of 525 patients who underwent RN between May 2007 and August 2011 at Tohoku University Hospital and its affiliated hospitals were prospectively evaluated. Overall, 422 patients were analyzed in this study. Results Independent preoperative factors associated with postnephrectomy renal function were different in males and females. Preoperative eGFR, age, tumor size, and body mass index (BMI) were independent factors in males, while tumor size and BMI were not independent factors in females. The equations developed to predict eGFR 1 year after RN were: Predicted eGFR in males (mL/min/1.73 m2)=27.99−(0.196×age)+(0.497×eGFR)+(0.744×tumor size)−(0.339×BMI); and predicted eGFR in females=44.57−(0.275×age)+(0.298×eGFR). The equations were validated in the validation dataset (R2=0.63, p<0.0001 and R2=0.31, p<0.0001, respectively). Conclusions The developed equations by sex enable better prediction of eGFR 1 year after RN. The equations will be useful for preoperative patient counseling and selection of the type of surgical procedure in elective partial or RN cases.

Phosphodiesterase type 5 inhibitor administered immediately after radical prostatectomy temporarily increases the need for incontinence pads, but improves final continence status

Purpose To evaluate the effects of phosphodiesterase type 5 inhibitor (PDE5i) on urinary continence recovery after bilateral nerve-sparing radical prostatectomy (BNSRP). Materials and Methods Between 2002 and 2012, 137 of 154 consecutive patients who underwent BNSRP in our institution retrospectively divided into 3 groups that included patients taking PDE5i immediately after surgery (immediate PDE5i group, n=41), patients starting PDE5i at an outpatient clinic after discharge (PDE5i group, n=56), and patients taking no medication (non-PDE5i group, n=40). Using self-administered questionnaires, the proportion of patients who did not require incontinence pads (pad-free patients) was calculated preoperatively and at 1, 3, 6, 12, 18, and 24 months after BNSRP. Severity of incontinence was determined based on the pad numbers and then compared among the 3 groups. Results Proportions of pad-free patients and severity of incontinence initially deteriorated in all of the groups to the lowest values soon after undergoing BNSRP, with gradual improvement noted thereafter. The deterioration was most prominent in the immediate PDE5i group. As compared to the non-PDE5i group, both the PDE5i and immediate PDE5i groups exhibited a better final continence status. Conclusions PDE5i improves final continence status. However, administration of PDE5i immediately after surgery causes a distinct temporary deterioration in urinary incontinence.