Genetic Deletion of Vascular Endothelial Growth Factor Receptor 2 in Endothelial Cells Leads to Immediate Disruption of Tumor Vessels and Aggravation of Hypoxia.

Vascular endothelial growth factor (VEGF) blockers are used widely in clinics to target various types of human cancer. Although VEGF blockers exert marked tumor suppressive effects, the therapeutic effects can be limited. Moreover, accumulating evidence shows that VEGF acts not just on endothelial cells but also on various nonendothelial cells, including tumor and immune cells, suggesting a need to revisit the bona fide action of VEGF on endothelial cells using specific genetic mouse models. Herein, tamoxifen-inducible endothelial-specific knockout mice lacking VEGF receptor 2 (Vegfr2), the major signal transducer for VEGF, were used. The initial event resulting from cessation of endothelial Vegfr2 signaling was vascular truncation and fragmentation, rather than maturation of abnormalized vessels. Although deletion of endothelial Vegfr2 suppressed intratumor hemorrhage, it enhanced hypoxia in tumor cells and reduced the number of infiltrating cytotoxic T cells, suggesting a profound reduction in intratumor blood flow. In various tissues, deletion of endothelial Vegfr2 induced regression of healthy capillaries in intestinal villi, substantiating intestinal perforation, which is one of the most common adverse effects of VEGF blockade in humans. Overall, the data suggest that some of the known effects of VEGF blockers on tumor vessels are caused by partial cessation of VEGF signaling, or by actions on nonendothelial cells. The results increase the understanding of the mechanisms underlying anti-angiogenic therapy.

Neuron-derived VEGF contributes to cortical and hippocampal development independently of VEGFR1/2-mediated neurotrophism.

Vascular endothelial growth factor (VEGF) is a potent mitogen critical for angiogenesis and organogenesis. Deletion or inhibition of VEGF during development not only profoundly suppresses vascular outgrowth, but significantly affects the development and function of various organs. In the brain, VEGF is thought to not only promote vascular growth, but also directly act on neurons as a neurotrophic factor by activating VEGF receptors. In the present study, we demonstrated that deletion of VEGF using hGfap-Cre line, which recombines genes specifically in cortical and hippocampal neurons, severely impaired brain organization and vascularization of these regions. The mutant mice had motor deficits, with lethality around the time of weaning. Multiple reporter lines indicated that VEGF was highly expressed in neurons, but that its cognate receptors, VEGFR1 and 2 were exclusive to endothelial cells in the brain. In accordance, mice lacking neuronal VEGFR1 and VEGFR2 did not exhibit neuronal deformities or lethality. Taken together, our data suggest that neuron-derived VEGF contributes to cortical and hippocampal development likely through angiogenesis independently of direct neurotrophic effects mediated by VEGFR1 and 2.

Fecalith in the Proximal Area of the Appendix is a Predictor of Failure of Nonoperative Treatment for Complicated Appendicitis in Adults.

BACKGROUND: The management of complicated appendicitis remains controversial, since this disease has various clinical presentations and is associated with high rates of adverse events. Although initial nonoperative treatment is generally employed for complicated appendicitis, its clinical presentation and the predictors of nonoperative treatment failure are unclear. METHODS: Patients diagnosed with complicated appendicitis in our hospital between April 2015 and March 2020 were enrolled. In total, 113 patients were classified into three categories: emergency appendectomy, failure of nonoperative treatment and successful nonoperative treatment. The primary outcome was the rate of failure of nonoperative treatment, as assessed by logistic regression analysis. The secondary outcomes were the operative procedures and postoperative courses of the three groups. RESULTS: Of 113 patients, 45 (40%) underwent emergency appendectomy, 25 (22%) failed nonoperative treatment, and 43 (38%) had successful nonoperative treatment. Among these successful cases, 38 patients (88%) underwent interval appendectomy. In multivariate analyses, the presence of a fecalith in the proximal area of the appendix was an independent risk factor for failure of nonoperative treatment (odds ratio, 20.5; 95% confidence interval, 4.37-95.7, P < 0.001). Postoperative outcomes were more unfavorable in cases of failed nonoperative treatment than in cases of emergency and interval appendectomy. CONCLUSIONS: The presence of a fecalith in the proximal area of the appendix is an independent predictor for failure of nonoperative treatment for complicated appendicitis in adults. Patients with this risk factor should be considered candidates for surgical treatment.

Placental labyrinth formation in mice requires endothelial FLRT2/UNC5B signaling.

The placental labyrinth is the interface for gas and nutrient exchange between the embryo and the mother; hence its proper development is essential for embryogenesis. However, the molecular mechanism underlying development of the placental labyrinth, particularly in terms of its endothelial organization, is not well understood. Here, we determined that fibronectin leucine-rich transmembrane protein 2 (FLRT2), a repulsive ligand of the UNC5 receptor family for neurons, is unexpectedly expressed in endothelial cells specifically in the placental labyrinth. Mice lacking FLRT2 in endothelial cells exhibited embryonic lethality at mid-gestation, with systemic congestion and hypoxia. Although they lacked apparent deformities in the embryonic vasculature and heart, the placental labyrinths of these embryos exhibited aberrant alignment of endothelial cells, which disturbed the feto-maternal circulation. Interestingly, this vascular deformity was related to endothelial repulsion through binding to the UNC5B receptor. Our results suggest that the proper organization of the placental labyrinth depends on coordinated inter-endothelial repulsion, which prevents uncontrolled layering of the endothelium.

Biological markers of invasive breast cancer.

Biological markers for breast cancer are biomolecules that result from cancer-related processes and are associated with particular clinical outcomes; they thus help predict responses to therapy. In recent years, gene expression profiling has made the molecular classification of breast cancer possible. Classification of breast cancer by immunohistochemical expression of estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2 and Ki-67 is standard practice for clinical decision-making. Assessments of hormone receptor expression and human epidermal growth factor receptor 2 overexpression help estimate benefits from targeted therapies and have greatly improved prognoses for women with these breast cancer types. Although Ki-67 positivity is associated with an adverse outcome, its clear identification is an aid to optimal disease management. Standardization of testing methodology to minimize inter-laboratory measurement variations is a remaining issue. Multi-gene assays provide prognostic information and identify those most likely to benefit from systemic chemotherapy. Incorporating molecular profiles with conventional pathological classification would be more precise, and could enhance the clinical development of personalized therapy in breast cancer.

Combined thoracoscopic and laparoscopic surgery for epiphrenic diverticulum with associated gastroesophageal reflux disease: a case report.

BACKGROUND: Surgery is indicated for symptomatic epiphrenic esophageal diverticula. Based on the features of a case, thoracoscopic or laparoscopic approaches may be used. Epiphrenic diverticula are often associated with esophageal motility disorders, but cases of reflux esophagitis have rarely been reported. In this report, we describe a case of an epiphrenic esophageal diverticulum with reflux esophagitis, which was successfully treated by thoracoscopic diverticulectomy and laparoscopic fundoplication. CASE PRESENTATION: A 69-year-old man visited the hospital with a chief complaint of eructation and hiccup. Upper gastrointestinal endoscopy revealed a diverticulum in the left wall of the esophagus, which was 37-45 cm distal to the incisors. High-resolution manometry (HRM) showed no esophageal motility disorders. Due to the large size of the diverticulum, a thoracoscopic resection of the esophageal diverticulum was performed. Additionally, the patient had reflux esophagitis due to a hiatal hernia. The anti-reflux mechanism would be more impaired during the diverticulectomy; therefore, we decided that anti-reflux surgery should be performed simultaneously. Thoracoscopic esophageal diverticulectomy and laparoscopic Dor fundoplication were performed. The patient had an uncomplicated postoperative course and was discharged on the tenth operative day. He has been symptom-free without acid secretion inhibitors for 21 months after the surgery. CONCLUSIONS: We described a rare case of a large epiphrenic diverticulum with reflux esophagitis. A good surgical outcome was achieved by thoracoscopic resection of the diverticulum and laparoscopic Dor fundoplication.

Essential updates 2020/2021: Recent topics in surgery and perioperative therapy for esophageal cancer.

In this review, we focused on four topics, namely, minimally invasive esophagectomy (MIE), robot-assisted minimally invasive esophagectomy (RAMIE), conversion and salvage surgery, and neoadjuvant and adjuvant therapy, based on notable reports published in the years 2020 and 2021. It seems that while the short-term outcomes of minimally invasive Ivor Lewis esophagectomy (MIE-IL) were better than those of open Ivor Lewis esophagectomy (OE-IL), there were no significant differences in the long-term outcomes between MIE-IL and OE-IL. Similarly, the short-term outcomes of minimally invasive McKeown esophagectomy (MIE-MK) were better than those of open McKeown esophagectomy (OE-MK), while there were no significant differences in the long-term outcomes between MIE-MK and OE-MK. Furthermore, the short-term outcomes of robot-assisted minimally invasive Ivor Lewis esophagectomy (RAMIE-IL) were superior to those of completely minimally invasive Ivor Lewis esophagectomy (CMIE-IL). On the other hand, there were advantages and disadvantages in relation to the short-term outcomes of robot-assisted minimally invasive McKeown esophagectomy (RAMIE-MK) as compared with completely minimally invasive McKeown esophagectomy (CMIE-MK). However, there were no significant differences in the long-term outcomes between RAMIE-MK and CMIE-MK. Further research is needed to evaluate of short-term and long-term outcomes of transmediastinal esophagectomy with and without robotic assistance. Both induction chemotherapy and induction chemoradiotherapy appear to be promising to secure a higher rate of conversion surgery. Neoadjuvant chemoimmunotherapy and chemoimmunoradiotherapy have shown promising results and are expected as new powerful therapies.

Laparoscopic Heller myotomy and Dor fundoplication following an unsuccessful peroral endoscopic myotomy.

BACKGROUND: Achalasia is an esophageal motility disorder that presents as dysphagia and severely affects quality of life. An esophageal myotomy has been the golden standard for treatment. Peroral endoscopic myotomy (POEM) as a first-line therapy has an acceptable outcome. However, after the clinical failure of POEM, appropriate second-line therapy is rather controversial. Here, we present the first published case in English of a patient who was successfully treated using laparoscopic Heller myotomy (LHM) with Dor fundoplication following an unsuccessful POEM. CASE PRESENTATION: A 64-year-old man with type 1 achalasia who had been previously treated with POEM visited our hospital for further treatment. After undergoing LHM with Dor fundoplication, his Eckardt score improved from 3 to 0 points. On a timed barium esophagogram (TBE), the barium height improved from 119 mm/119 mm (1 min/5 min) to 50 mm/45 mm. No significant complications have occurred postoperatively for 1 year. CONCLUSION: Treating refractory achalasia is challenging, and treatment options are controversial. LHM with Dor fundoplication after POEM could be a safe and efficient option for the treatment of refractory achalasia.

Spatial heterogeneity of bone marrow endothelial cells unveils a distinct subtype in the epiphysis.

Bone marrow endothelial cells (BMECs) play a key role in bone formation and haematopoiesis. Although recent studies uncovered the cellular taxonomy of stromal compartments in the bone marrow (BM), the complexity of BMECs is not fully characterized. In the present study, using single-cell RNA sequencing, we defined a spatial heterogeneity of BMECs and identified a capillary subtype, termed type S (secondary ossification) endothelial cells (ECs), exclusively existing in the epiphysis. Type S ECs possessed unique phenotypic characteristics in terms of structure, plasticity and gene expression profiles. Genetic experiments showed that type S ECs atypically contributed to the acquisition of bone strength by secreting type I collagen, the most abundant bone matrix component. Moreover, these cells formed a distinct reservoir for haematopoietic stem cells. These findings provide the landscape for the cellular architecture in the BM vasculature and underscore the importance of epiphyseal ECs during bone and haematopoietic development.

Tumor-specific interendothelial adhesion mediated by FLRT2 facilitates cancer aggressiveness.

Blood vessel abnormalization alters cancer cell metabolism and promotes cancer dissemination and metastasis. However, the biological features of the abnormalized blood vessels that facilitate cancer progression and whether they can be targeted therapeutically have not been fully investigated. Here, we found that an axon guidance molecule, fibronectin leucine-rich transmembrane protein 2 (FLRT2), is expressed preferentially in abnormalized vessels of advanced colorectal cancers in humans and that its expression correlates negatively with long-term survival. Endothelial cell-specific deletion of Flrt2 in mice selectively pruned abnormalized vessels, resulting in a unique metabolic state termed "oxygen-glucose uncoupling," which suppressed tumor metastasis. Moreover, Flrt2 deletion caused an increase in the number of mature vessels, resulting in a significant increase in the antitumor effects of immune checkpoint blockers. Mechanistically, we found that FLRT2 forms noncanonical interendothelial adhesions that safeguard against oxidative stress through homophilic binding. Together, our results demonstrated the existence of tumor-specific interendothelial adhesions that enable abnormalized vessels to facilitate cancer aggressiveness. Targeting this type of adhesion complex could be a safe and effective therapeutic option to suppress cancer progression.

Blood and lymphatic systems are segregated by the FLCN tumor suppressor.

Blood and lymphatic vessels structurally bear a strong resemblance but never share a lumen, thus maintaining their distinct functions. Although lymphatic vessels initially arise from embryonic veins, the molecular mechanism that maintains separation of these two systems has not been elucidated. Here, we show that genetic deficiency of Folliculin, a tumor suppressor, leads to misconnection of blood and lymphatic vessels in mice and humans. Absence of Folliculin results in the appearance of lymphatic-biased venous endothelial cells caused by ectopic expression of Prox1, a master transcription factor for lymphatic specification. Mechanistically, this phenotype is ascribed to nuclear translocation of the basic helix-loop-helix transcription factor Transcription Factor E3 (TFE3), binding to a regulatory element of Prox1, thereby enhancing its venous expression. Overall, these data demonstrate that Folliculin acts as a gatekeeper that maintains separation of blood and lymphatic vessels by limiting the plasticity of committed endothelial cells.