Angiopoietin-2 induces angiogenesis via exosomes in human hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) is the most common primary liver cancer and is a highly vascularized solid tumor. Angiopoietin-2 (ANGPT2) has been described as an attractive target for antiangiogenic therapy. Exosomes are small extracellular vesicles secreted by most cell types and contribute to cell-to-cell communication by delivering functional cargo to recipient cells. The expression of ANGPT2 in tumor-derived exosomes remains unknown. METHODS: We detected the ANGPT2 expression in HCC-derived exosomes by immunoblotting, enzyme-linked immunosorbent assay and immunogold labeling, then observed exosomal ANGPT2 internalization and recycling by confocal laser scanning microscopy, co-immunoprecipitation and immunoblotting. We used two HCC cell lines (Hep3B and MHCC97H) to overexpress ANGPT2 by lentivirus infection or knockdown ANGPT2 by the CRISPR/Cas system, then isolated exosomes to coculture with human umbilical vein endothelial cells (HUVECs) and observed the angiogenesis by Matrigel microtubule formation assay, transwell migration assay, wound healing assay, cell counting kit-8 assay, immunoblotting and in vivo tumorigenesis assay. RESULTS: We found that HCC-derived exosomes carried ANGPT2 and delivered it into HUVECs by exosome endocytosis, this delivery led to a notable increase in angiogenesis by a Tie2-independent pathway. Concomitantly, we observed that HCC cell-secreted exosomal ANGPT2 was recycled by recipient HUVECs and might be reused. In addition, the CRISPR-Cas systems to knock down ANGPT2 significantly inhibited the angiogenesis induced by HCC cell-secreted exosomal ANGPT2, and obviously suppressed the epithelial-mesenchymal transition activation in HCC. CONCLUSIONS: Taken together, these results reveal a novel pathway of tumor angiogenesis induced by HCC cell-secreted exosomal ANGPT2 that is different from the classic ANGPT2/Tie2 pathway. This way may be a potential therapeutic target for antiangiogenic therapy. Video Abstract.

Laparoscopic duodenum-preserving total pancreatic head resection: a novel surgical approach for benign or low-grade malignant tumors.

BACKGROUND: Duodenum-preserving total pancreatic head resection (DPPHRt) is an accepted alternative surgical procedure for benign or low-grade malignant tumors of the pancreatic head by preserving the duodenum with its intact blood supply from the pancreatic duodenal arterial arcade. This study describes our experience in laparoscopic DPPHRt (LDPPHRt). To our knowledge, this is the first description of this novel minimally invasive operation. METHODS: From August 2016 to May 2017, all consecutive patients who underwent LDPPHRt for pancreatic head lesions at the HPB Surgery Department, Sun Yat-Sen Memorial Hospital in Guangzhou, China were enrolled into this retrospective study. RESULTS: There were ten women and two men. The average age was 37.3 years (range 8-61 years). The average diameter of the pancreatic head lesions on pre-operative CT/MR was 3.7 cm (range 2-4.8 cm). All the LDPPHRt procedures were performed successfully. There was no peri-operative death. The average operative time was 272.5 min (range 210-320 min). The average blood loss was 215 ml (range 50-450 ml). Post-operative complications included pancreatic fistula grade B (two patients, or 16.7%) and biliary fistula (two patients, or 16.7%). All the complications responded well to conservative treatment. The mean post-operative hospital stay was 11.5 days (range 6-25 days). CONCLUSIONS: LDPPHRt provided a minimally invasive approach with good organ-preservation for benign or low-grade malignant tumors of the pancreatic head. The long-term oncological outcomes, and the exocrine and endocrine pancreatic functions after this operation require further studies.