Abstract
BackgroundTumor lymphangiogenesis plays an important role in promoting growth and metastasis of tumors, but no antilymphangiogenic agent is used clinically. Based on the effect of norcantharidin (NCTD) on lymphangiogenesis of human lymphatic endothelial cells (LECs), we firstly investigated the antilymphangiogenic activity of NCTD as a tumor lymphangiogenic inhibitor for human colonic adenocarcinomas (HCACs).MethodsIn vivo and in vitro experiments to determine the effects of NCTD on tumor growth and lymphangiogenesis of the in-situ colonic xenografts in nude mice, and lymphatic tube formation of the three-dimensional (3-D) of the co-culture system of HCAC HT-29 cells and LECs were done. Proliferation, apoptosis, migration, invasion, Ki-67, Bcl-2 and cell cycle of LECs and the co-culture system in vitro were respectively determined. Streparidin-peroxidase staining, SABC, western blotting and RT-PCR were respectively used to examine the expression of LYVE-1, D2-40, CK20 (including their LMVD), and VEGF-A, VEGF-C, VEGF-D, VEGFR-2 and VEGFR-3 in vitro and in vivo.ResultsNCTD inhibited tumor growth and lymphangiogenesis of the in-situ colonic xenografts in vivo, and these observations were confirmed by facts that lymphatic tube formation, proliferation, apoptosis, migration, invasion, S-phase cell cycle, and Ki-67 and Bcl-2 expression in vitro, and LYVE-1, D2-40, CK20 expression and their LMVD in vitro and in vivo were inhibited and affected. Furthermore, the expression of VEGF-A, VEGF-C, VEGF-D, VEGFR-2 and VEGFR-3 at protein/mRNA levels in the process of lymphatic tube formation in vitro and tumor lymphangiogenesis in vivo was downregulated; NCTD in combination with mF4-31C1 or Sorafenib enhanced these effects.ConclusionsNCTD inhibits tumor growth and lymphangiogenesis of HCACs through “multi-points priming” mechanisms i.e. affecting related malignant phenotypes, inhibiting Ki-67 and Bcl-2 expression, inducing S-phase cell cycle arrest, and directly or indirectly downregulating VEGF-A,-C,-D/VEGFR-2,-3 signaling pathways. The present finding strongly suggests that NCTD could serve as a potential antilymphangiogenic agent for tumor lymphangiogenesis and is of importance to explore NCTD is used for antitumor metastatic comprehensive therapy for HCACs.
Highlights
Tumor lymphangiogenesis plays an important role in promoting growth and metastasis of tumors, but no antilymphangiogenic agent is used clinically
We further investigated the effects of NCTD on lymphatic tube formation of the co-culture system consisting of human colonic adenocarcinomas (HCACs) HT-29 cells and LECs i.e. primary human dermal lymphatic endothelial cells (HDLECs) in vitro, tumor growth and lymphangiogenesis of the in-situ colonic xenografts in nude mice in vivo, and the related signaling pathways such as VEGF-C, −D/VEGFR-3 and possible crosstalk pathway VEGF-A/VEGFR-2 in vitro and in vivo, so as to explore that it is whether served as a target inhibitor for tumor lymphangiogenesis and lymphatic metastasis, and a potential small-molecule synthetic antilymphangiogenic agent for HCACs
NCTD inhibits growth of the in-situ colonic xenografts in vivo We previously reported that NCTD has multiple antitumor activities against different tumor cells [9, 12, 51, 61, 63], whereas Sorafenib is an oral multi-kinase inhibitor that blocks proliferation and carcinogenesis of different tumor cells including colonic adenocarcinoma cells by a dual mechanism including targeting several receptor tyrosine kinases such as VEGFR-2 and VEGFR-3 [37, 38]
Summary
Tumor lymphangiogenesis plays an important role in promoting growth and metastasis of tumors, but no antilymphangiogenic agent is used clinically. Metastatic spread of tumor cells is the most lethal aspect of cancer and often occurs via the lymphatic vessels, whereas lymphangiogenesis refers to the formation of lymphatic vessels from preexisting lymphatic vessels, which plays an important role in promoting growth and metastatic spread of tumor cells [25]. Extensive studies have showed that tumor- or stromal-secreted cytokines such as VEGF-C and VEGF-D, and their cognate receptor tyrosine kinase VEGFR-3 located on LECs are critical regulators of lymphangiogenesis, these molecules advance or regulate proliferation, migration, metastasis and survival of LECs, growth of new lymphatic capillaries and lymphatic tube formation in tumorigenesis, promote metastatic spread of tumor cells to lymph nodes [20, 28]. In the design of anti-lymphangiogenesis, in addition to the VEGFC,-D/ VEGFR-3 signaling pathways, the VEGF-A or -B/ VEGFR-2 signaling pathways should be considered as potential therapy targets for primary tumors and metastasis
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
