Increased vascular endothelial growth factor-C expression is insufficient to induce lymphatic metastasis in human soft-tissue sarcomas.
OBJECTIVE
Unlike carcinomas, soft-tissue sarcoma (STS) rarely exhibit lymphatic spread. Consequently, we examined expression and function of vascular endothelial growth factor (VEGF)-C and STS-associated lymphatic vessel density (LVD) components of this process.


METHODS
VEGF-C and VEGF-A mRNA and VEGF-C protein expression were evaluated in STS, STS cell lines, and breast cancers (reverse transcription-PCR, quantitative reverse transcription-PCR, and ELISA). STS cell conditioned medium after VEGF-C knockdown was examined for endothelial cell proliferation and migration effects (MTS and migration assays). Paraffin-embedded human lymph node-negative and lymph node-positive STS and lymph node-negative and lymph node-positive breast cancers were examined for VEGF-C, D2-40, and CD31 expression (immunohistochemistry). LVD differences were analyzed by Wilcoxon rank-sum tests.


RESULTS
STS and breast cancer VEGF-C expression was comparable and higher than normal tissue levels. STS cells secreted functional VEGF-C: STS conditioned medium induced lymphatic endothelial cell proliferation and migration, which was abrogated by STS cell VEGF-C knockdown. STS and breast cancer intratumoral LVD was similar. STS peritumoral LVD (PT-LVD) was reduced versus breast cancer PT-LVD (P < 0.001). Significantly higher PT-LVD was observed in lymph node-positive versus lymph node-negative STS; lymphatic spreading STS subtypes also had higher LVD. STS VEGF-C expression and PT-LVD lacked correlation, and many lymph node-negative STS had high PT-LVD, suggesting complexity in this metastatic process.


CONCLUSIONS
Compared with breast cancers, STS exhibited lower PT-LVD independent of VEGF-C expression, which may underlie STS lymph node metastasis rarity. Moreover, lymphatic vessels appear necessary but not sufficient to sustain STS lymphatic spread. Examining STS "nonlymphatic" dissemination may help elucidate mechanisms of lymphatic spread, insights critically important to cancer metastasis control.
Lahat
Guy
G
Department of Surgical Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.
Lazar
Alexander
A
Wang
Xuemei
X
Wang
Wei-Lien
WL
Zhu
Quan-Sheng
QS
Hunt
Kelly K
KK
Pollock
Raphael E
RE
Lev
Dina
D
D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology; D042783:Endothelial Cells / Q000502:physiology; D055785:Gene Knockdown Techniques; D006801:Humans; D008207:Lymphatic Metastasis; D018190:Neoplasm, Lymphatic Tissue / Q000378:metabolism; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D012509:Sarcoma / Q000378:metabolism / Q000473:pathology*; D042582:Vascular Endothelial Growth Factor C / Q000096:biosynthesis* / Q000235:genetics
D019408:Platelet Endothelial Cell Adhesion Molecule-1; D034741:RNA, Small Interfering; D042582:Vascular Endothelial Growth Factor C