BackgroundTumor endothelial cells (TECs) perform tumor angiogenesis, which is essential for tumor growth and metastasis. Tumor cells produce large amounts of lactic acid from glycolysis; however, the mechanism underlying the survival of TECs to enable tumor angiogenesis under high lactic acid conditions in tumors remains poorly understood.MethodologyThe metabolomes of TECs and normal endothelial cells (NECs) were analyzed by capillary electrophoresis time-of-flight mass spectrometry. The expressions of pH regulators in TECs and NECs were determined by quantitative reverse transcription-PCR. Cell proliferation was measured by the MTS assay. Western blotting and ELISA were used to validate monocarboxylate transporter 1 and carbonic anhydrase 2 (CAII) protein expression within the cells, respectively. Human tumor xenograft models were used to access the effect of CA inhibition on tumor angiogenesis. Immunohistochemical staining was used to observe CAII expression, quantify tumor microvasculature, microvessel pericyte coverage, and hypoxia.ResultsThe present study shows that, unlike NECs, TECs proliferate in lactic acidic. TECs showed an upregulated CAII expression both in vitro and in vivo. CAII knockdown decreased TEC survival under lactic acidosis and nutrient-replete conditions. Vascular endothelial growth factor A and vascular endothelial growth factor receptor signaling induced CAII expression in NECs. CAII inhibition with acetazolamide minimally reduced tumor angiogenesis in vivo. However, matured blood vessel number increased after acetazolamide treatment, similar to bevacizumab treatment. Additionally, acetazolamide-treated mice showed decreased lung metastasis.ConclusionThese findings suggest that due to their effect on blood vessel maturity, pH regulators like CAII are promising targets of antiangiogenic therapy. Graphical abstract

Reactive oxygen species (ROS) are unstable molecules that activate oxidative stress. Because of the insufficient blood flow in tumors, the tumor microenvironment is often exposed to hypoxic condition and nutrient deprivation, which induces ROS accumulation. We isolated tumor endothelial cells (TECs) and found that they have various abnormalities, although the underlying mechanisms are not fully understood. Here we showed that ROS were accumulated in tumor blood vessels and ROS enhanced TEC migration with upregulation of several angiogenesis related gene expressions. It was also demonstrated that these genes were upregulated by regulation of Nuclear factor erythroid 2-related factor 2 (NRF2). Among these genes, we focused on Biglycan, a small leucine-rich proteoglycan. Inhibition of Toll-like receptors 2 and 4, known BIGLYCAN (BGN) receptors, cancelled the TEC motility stimulated by ROS. ROS inhibited NRF2 expression in TECs but not in NECs, and NRF2 inhibited phosphorylation of SMAD2/3, which activates transcription of BGN. These results indicated that ROS-induced BGN caused the pro-angiogenic phenotype in TECs via NRF2 dysregulation.

It has been described that tumor progression has many similarities to inflammation and wound healing in terms of the signaling processes involved. Among biological responses, angiogenesis, which is necessary for tumor progression and metastasis, is a common hallmark; therefore, tumor blood vessels have been considered as important therapeutic targets in anticancer therapy. We focused on pentraxin 3 (PTX3), which is a marker of cancer-related inflammation, but we found no reports on its expression and function in tumor blood vessels. Here we showed that PTX3 is expressed in mouse and human tumor blood vessels based on immunohistochemical analysis. We found that PTX3 is upregulated in primary mouse and human tumor endothelial cells compared to normal endothelial cells. We also showed that PTX3 plays an important role in the proliferation of the tumor endothelial cells. These results suggest that PTX3 is an important target for antiangiogenic therapy.

Tumor angiogenesis research and antiangiogenic drug development make use of cultured endothelial cells (ECs) including the human microvascular ECs among others. However, it has been reported that tumor ECs (TECs) are different from normal ECs (NECs). To functionally validate antiangiogenic drugs, cultured TECs are indispensable tools, but are not commercially available. Primary human TECs are available only in small quantities from surgical specimens and have a short life span in vitro due to their cellular senescence. We established immortalized human TECs (h-imTECs) and their normal counterparts (h-imNECs) by infection with lentivirus producing simian virus 40 large T antigen and human telomerase reverse transcriptase to overcome the replication barriers. These ECs exhibited an extended life span and retained their characteristic endothelial morphology, expression of endothelial marker, and ability of tube formation. Furthermore, h-imTECs showed their specific characteristics as TECs, such as increased proliferation and upregulation of TEC markers. Treatment with bevacizumab, an antiangiogenic drug, dramatically decreased h-imTEC survival, whereas the same treatment failed to alter immortalized NEC survival. Hence, these h-imTECs could be a valuable tool for drug screening to develop novel therapeutic agents specific to TECs or functional biological assays in tumor angiogenesis research.

Background Hypotension during anesthesia induction is a common event, and occurs more frequently in patients with hypertension than in healthy individuals. Intraoperative hypotension in non-cardiac surgery is reportedly associated with various postoperative complications. However, the predictors of hypotension during anesthesia induction in patients with hypertension have not yet been ascertained. Therefore, we aimed to determine the predictors of hypotension during anesthesia induction in patients with hypertension on medication focusing on the half-life of the medication used. Methods In this retrospective observational study, we enrolled patients with hypertension on medication who underwent general anesthesia for oral and maxillofacial surgery between January 1, 2013, and December 31, 2019. Multivariable logistic regression analysis was conducted to test for associations between clinical factors and hypotension during anesthesia induction in patients with hypertension on medication. Results A total of 395 patients were included in this study. The risk factors for hypotension during anesthesia induction in patients with hypertension on medication were pre-induction mean arterial blood pressure (adjusted unit odds ratio, 0.96 [95% confidence interval, 0.94 to 0.98]), female sex (adjusted odds ratio [aOR], 1.63 [1.03 to 2.57]), regular use of angiotensin receptor blockers (ARBs)/angiotensin-converting enzyme inhibitors (ACE-Is) with a long half-life (vs. no regular use of ARBs/ACE-Is aOR, 4.02 [1.77 to 9.12]; vs. regular use of ARBs/ACE-Is with a short-to-middle half-life aOR, 3.17 [1.46 to 6.85]), and regular use of beta blockers (aOR, 2.45 [1.19 to 5.04]). Regular use of calcium channel blockers (aOR, 0.44 [0.25 to 0.77]) was a suppressive factor for hypotension during anesthesia induction in patients with hypertension. Conclusions In patients with hypertension on medication, regular use of ARBs/ACE-Is with a long half-life, regular use of beta blockers, low pre-induction mean arterial blood pressure, and female sex were risk factors for hypotension during anesthesia induction. Notably, regular use of ARBs/ACE-Is with a long half-life was a high-risk factor for hypotension during anesthesia induction in patients with hypertension on medication even after a 24-h preoperative withdrawal period.