Rapamycin suppresses angiogenesis and lymphangiogenesis in melanoma by downregulating VEGF-A/VEGFR-2 and VEGF-C/VEGFR-3 expression
Authors Wang M, Xu Y, Wen GZ, Wang Q, Yuan SM
Received 13 February 2019
Accepted for publication 26 April 2019
Published 13 June 2019 Volume 2019:12 Pages 4643—4654
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Ms Aruna Narula
Peer reviewer comments 2
Editor who approved publication: Dr XuYu Yang
Min Wang,1 Yuan Xu,1 Guo-Zhong Wen,2 Qian Wang,3 Si-Ming Yuan1–3
1Department of Plastic Surgery, Jinling Hospital, Nanjing School of Clinical Medicine, Southern Medical University, Nanjing, Jiangsu 210002, People’s Republic of China; 2Department of Plastic Surgery, Jinling Hospital, Nanjing Medical University, Nanjing, Jiangsu 210002, People’s Republic of China; 3Department of Plastic Surgery, Jinling Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu 210002, People’s Republic of China
Background: Cutaneous melanoma is a highly malignant tumor which tends to metastasize in the early stage and leads to poor prognosis. Hematogenous and lymphatic metastasis are common in the dissemination of melanoma. Rapamycin, an mTOR inhibitor, was reported to have anti-angiogenic and anti-lymphangiogenic properties.
Aim: The aim of this study was to investigate if rapamycin can inhibit the formation of blood vessels and lymphatic vessels in melanoma.
Methods: A melanoma xenograft model was generated by subcutaneously transplanting A375 human melanoma cells into the back of immunodeficient mice. Two weeks after cell transplantation, rapamycin was injected intraperitoneally every other day seven times. Then, tumors were harvested.Hematoxylin-eosin (H-E)staining, immunohistochemical staining, Western blot, and quantitative PCR were performed to observe the pathological structure of the tumor, the distribution of blood vessels and lymphatic vessels, and the expression of mTOR signal pathway, VEGF-A/VEGFR-2, and VEGF-C/VEGFR-3.
Results: The results showed that CD34(+) blood vessels and LYVE-1(+) lymphatic vessels decreased in the peritumor and intratumor region in rapamycin-treated tumors. Expression of p-4EBP1 and p-S6K1 proteins was downregulated. Expression of both proteins and mRNAs of VEGF-A/VEGFR-2 and VEGF-C/VEGFR-3 was downregulated.
Conclusion: In conclusion, rapamycin suppresses angiogenesis and lymphangiogenesis in melanoma by blocking the mTOR signal pathway and subsequently downregulating the expression of VEGF-A/VEGFR-2 and VEGF-C/VEGFR-3. Therefore, targeted therapy via mTOR signal pathway may control the hematogenous and lymphatic metastasis of melanoma, and even prolong patients’ survival time.
Keywords: melanoma, rapamycin, angiogenesis, lymphangiogenesis
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