[Clinical Outcome of Microsatellite Instability-High Patients Treated with Pembrolizumab and Genetic Counseling].

Prospective studies have demonstrated the efficacy of pembrolizumab in patients with previously treated unresectable or metastatic microsatellite instability-high(MSI-H)cancers. Pembrolizumab has been covered by the Japanese health insurance system since December 2018. The frequency of MSI-H in patients is as low as approximately 2%. In addition, some patients with MSI-H cancers are diagnosed with Lynch syndrome. In the present study, we retrospectively investigated patients who received MSI testing at Kitasato University Hospital from April 2019 to June 2020. We also investigated the therapeutic effect of pembrolizumab for MSI-H cancers and patients who received genetic counseling for Lynch syndrome. Results identified that 5 out of 263 patients who underwent MSI testing(1.9%)had MSI-H. The therapeutic outcomes of pembrolizumab in those patients were as follows: 1(20%)complete response, 3(60%)partial response, and 1(20%) progressive disease. The positive-outcome rate of MSI-H treatment in our institution was comparable to that in the previous reports. The high response rate of pembrolizumab was confirmed in the present study. Four out of 5 patients received genetic counseling at the genetic clinic, and 1 patient underwent genetic testing for Lynch syndrome. No deleterious variant of Lynch syndrome was detected in the genetic testing.

[In Situ Ductal Carcinoma with Hereditary Breast and Ovarian Cancer Syndrome in a Patient Who Received Contralateral Risk-Reducing Mastectomy-A Case Report].

A woman in her 30s presented to our hospital with the chief complaint of a right breast mass after the birth of her first child. She was diagnosed as having right invasive ductal carcinoma of Luminal-B type and T3N3cM0, stage Ⅲc. While undergoing neoadjuvant chemotherapy, she received genetic counseling and underwent genetic testing and was determined to have deleterious BRCA1 and BRCA2 mutations. After completing chemotherapy, she underwent a right total mastectomy and axillary lymph node dissection. Two years postoperatively, she requested to undergo a contralateral risk-reducing mastectomy( CRRM)of her left breast. Therefore, CT and breast MRI were performed to confirm the absence of contralateral lesions and distant metastases, and subsequently, CRRM was performed. Postoperative pathology results showed non-invasive ductal carcinoma lesions at 5 sites. In the case of hereditary breast and ovarian cancer syndrome such as in this study, lesions may be discovered at an early stage by performing risk-reducing mastectomy.

Regulators of Epithelial Sodium Channels in Aldosterone-Sensitive Distal Nephrons (ASDN): Critical Roles of Nedd4L/Nedd4-2 and Salt-Sensitive Hypertension.

Ubiquitination is a representative, reversible biological process of the post-translational modification of various proteins with multiple catalytic reaction sequences, including ubiquitin itself, in addition to E1 ubiquitin activating enzymes, E2 ubiquitin conjugating enzymes, E3 ubiquitin ligase, deubiquitinating enzymes, and proteasome degradation. The ubiquitin-proteasome system is known to play a pivotal role in various molecular life phenomena, including the cell cycle, protein quality, and cell surface expressions of ion-transporters. As such, the failure of this system can lead to cancer, neurodegenerative diseases, cardiovascular diseases, and hypertension. This review article discusses Nedd4-2/NEDD4L, an E3-ubiquitin ligase involved in salt-sensitive hypertension, drawing from detailed genetic dissection analysis and the development of genetically engineered mice model. Based on our analyses, targeting therapeutic regulations of ubiquitination in the fields of cardio-vascular medicine might be a promising strategy in future. Although the clinical applications of this strategy are limited, compared to those of kinase systems, many compounds with a high pharmacological activity were identified at the basic research level. Therefore, future development could be expected.

An isoform of Nedd4-2 is critically involved in the renal adaptation to high salt intake in mice.

Epithelial sodium channels (ENaCs) play critical roles in the maintenance of fluid and electrolyte homeostasis, and their genetic abnormalities cause one type of hereditary salt-sensitive hypertension, Liddle syndrome. As we reported previously, both human and rodent Nedd4L/Nedd4-2 showed molecular diversity, with and without a C2 domain in their N-terminal. Nedd4L/Nedd4-2 isoforms with a C2 domain are hypothesized to be related closely to ubiquitination of ENaCs. We generated Nedd4-2 C2 domain knockout mice. We demonstrate here that loss of Nedd4-2 C2 isoform causes salt-sensitive hypertension under conditions of a high dietary salt intake in vivo. The knockout mice had reduced urinary sodium excretion, osmotic pressure and increased water intake and urine volume with marked dilatation of cortical tubules while receiving a high salt diet. To the contrary, there was no difference in metabolic data between wild-type and knockout mice receiving a normal control diet. In the absence of Nedd4-2 C2 domain, a high salt intake accelerated ENaC expression. Coimmunoprecipitation studies revealed suppressed ubiquitination for ENaC with a high salt intake. Taken together, our findings demonstrate that during a high oral salt intake the Nedd4-2 C2 protein plays a pivotal role in maintaining adaptive salt handling in the kidney.

Identification of bona fide alternative renin transcripts expressed along cortical tubules and potential roles in promoting insulin resistance in vivo without significant plasma renin activity elevation.

Renin belongs to a family of aspartyl proteases and is the rate-limiting enzyme in the synthesis of the potent vasoactive peptide angiotensin II. Processing of renal renin has been extensively investigated in juxtaglomerular granular cells, in which prorenin and active renin are present in secretory condensed granules. Previous studies demonstrated alternative renin transcription in rat adrenal glands. Different studies reported novel intracellular forms of renin deduced from novel 5' variants derived from renin mRNA in both mice and humans. Comprehensive detailed studies in genetically engineered mice showed that both a secreted and an intracellular form of renin plays divergent mechanism regulating fluid intake and metabolism by the brain renin-angiotensin system; however, the presence, regulation, and functions of these renin isoforms in kidney and adrenal gland are not fully understood in mice. To investigate the characteristics of renin isoforms in mice, we performed a systematic inventory of renin transcripts of mice with and without a duplication of the renin gene alternatively from previous studies. We discovered a novel isoform of renin of the Ren2 gene, which conserved functionally important residues of the prosegment and incomplete isoforms of the Ren1C/D gene lacking a pre-pro segment. In situ hybridization assays revealed alternative renin isoforms expressed along cortical tubules. Newly generated transgenic mice with systemic overexpression of alternative renin transcript showed enhanced local angiotensin II generation without elevation of plasma renin activity and systemic insulin resistance in vivo, providing new pathophysiological insights into insulin resistance exaggerated by bona fide renin isoform.

Renin angiotensin antagonists normalize aberrant activation of epithelial sodium channels in sodium-sensitive hypertension.

Epithelial sodium channels (ENaC) are ion transporters in the aldosterone-sensitive distal nephron that play an important role in sodium reabsorption in the terminal nephron. Our study of inbred C57Bl6/J mice given a high-sodium diet showed increased ENaC expression accompanied by tubular renin activation on qRT-PCR of laser-captured tubule specimens and Western blotting of membrane proteins, despite inhibition of aldosterone. Treatment with an angiotensin-converting-enzyme inhibitor (ACEI) or an angiotensin receptor blocker (ARB) effectively lowered blood pressure. In addition to lowering blood pressure, ACEI and ARB inhibition downregulated ENaC and renin expression in renal tubules. These effects would act to suppress sodium reabsorption via ENaC and normalize molecular mechanisms that elevate blood pressure in response to increased salt intake.

Identification of NPC2 protein as interaction molecule with C2 domain of human Nedd4L.

Epithelial sodium channels (ENaC) located along the aldosterone-sensitive distal nephron (ASDN) play a pivotal role in the homeostasis of sodium balance. Among various modulating proteins, E3 ubiquitin ligase, Nedd4L, binds the PY motif of ENaC COOH terminals and catalyzes ubiquitination of the NH(2) terminal of the protein for subsequent degradation. One of the isoforms of human Nedd4L with evolutionarily new C2 domain was reported to play a significant role for degradating cell surface ENaC with interfering with wild isoforms by us previously. We focused the current analyses on isolating the binding molecules with C2 domain using yeast two-hybrid screening to elucidate further molecular interactions between ENaC and Nedd4L. We found NPC2, also known as HE-1, bind C2 domain of human Nedd4L and express along ASDN colocalized with Nedd4L. Additionally, in experiments using a model of salt-sensitive hypertension in Dahl rats, we provided evidence suggesting that transcriptional regulation and activation of NPC2 protein depends on sodium intake. NPC2 might regulate sodium reabsorption in the terminal nephron by interacting with ENaC-Nedd4L system.

Utility and feasibility of a new programmable home blood pressure monitoring device for the assessment of nighttime blood pressure.

BACKGROUND: Recent evidence indicates that both ambulatory blood pressure monitoring (ABPM) and home blood pressure monitoring (HBPM) are more useful than the measurement of office blood pressure for evaluating cardiovascular risks in subjects with hypertension. The major advantage of ABPM over HBPM is the ability to measure nighttime blood pressure and ambulatory blood pressure during the day. A newly developed, programmable HBPM device (HEM-5041, Omron Healthcare, [corrected] Kyoto, Japan) can record blood pressure up to 600 [corrected] times and measure nighttime blood pressure automatically. METHODS: To validate the utility, feasibility, and safety of this device, we measured blood pressure by HBPM using HEM-5041 and by ABPM and compared the values in healthy volunteers. RESULTS: As compared with ABPM, daytime blood pressures, coefficients of variation for systolic blood pressure, diastolic blood pressure, and pulse rate, and the percentage nighttime fall in these variables were significantly lower with HBPM. However, nighttime blood pressures did not significantly differ between HBPM and ABPM. The results of a questionnaire survey indicated that the subjects were more comfortable when blood pressure was measured by HBPM than by ABPM, whereas the quality of sleep was similar. CONCLUSIONS: Our results suggest that HEM-5041 is useful for evaluating nighttime blood pressures as well as nighttime blood pressure falls, without causing clinically significant discomfort.

Expression, transcription, and possible antagonistic interaction of the human Nedd4L gene variant: implications for essential hypertension.

Net sodium balances in humans are maintained through various ion transporters expressed along the entire nephron. Among these ion transporters, epithelial sodium channels (ENaC) located along the aldosterone-sensitive distal nephron (ASDN) play a pivotal role in the homeostasis of sodium balance. This is supported by analyses of inherited hypertensive disorders, showing that genes encoding ENaC and other modulatory proteins cause hereditary hypertension, such as Liddle syndrome. Among various modulating proteins, E3 ubiquitin ligase, Nedd4L, binds the PY motif of ENaC COOH terminals and catalyzes ubiquitination of the NH(2) terminus of the protein for subsequent degradation. Both evolutionarily conserved and evolutionarily new C2 domains of human Nedd4L, a cryptic splice variant resulting in a disrupted isoform product formed by a frame-shift mutation, were reported previously. We focused on one of the isoforms, isoform I, generated by SNP (rs4149601), and studied its expression and interactions with other isoforms by molecular biological, immunohistochemical, and electrophysiological methods. We found that isoform I may interact with other human isoforms in a dominant-negative fashion. Such interactions might abnormally increase sodium reabsorption. Taken together, our analyses suggest that the human Nedd4L gene, especially the evolutionarily new isoform I, is a candidate gene for hypertension.