Hypoxia regulates cross-talk between Syk and Lck leading to breast cancer progression and angiogenesis.
Hypoxia is a key parameter that controls tumor angiogenesis and malignant progression by regulating the expression of several oncogenic molecules. The nonreceptor protein-tyrosine kinases Syk and Lck play crucial roles in the signaling mechanism of various cellular processes. The enhanced expression of Syk in normal breast tissue but not in malignant breast carcinoma has prompted us to investigate its potential role in mammary carcinogenesis. Accordingly, we hypothesized that hypoxia/reoxygenation (H/R) may play an important role in regulating Syk activation, and Lck may be involved in this process. In this study, we have demonstrated that H/R differentially regulates Syk phosphorylation and its subsequent interaction and cross-talk with Lck in MCF-7 cells. Moreover, Syk and Lck play differential roles in regulating Sp1 activation and expressions of melanoma cell adhesion molecule (MelCAM), urokinase-type plasminogen activator (uPA), matrix metalloproteinase-9 (MMP-9), and vascular endothelial growth factor (VEGF) in response to H/R. Overexpression of wild type Syk inhibited the H/R-induced uPA, MMP-9, and VEGF expression but up-regulated MelCAM expression. Our data also indicated that MelCAM acts as a tumor suppressor by negatively regulating H/R-induced uPA secretion and MMP-9 activation. The mice xenograft study showed the cross-talk between Syk and Lck regulated H/R-induced breast tumor progression and further correlated with the expressions of MelCAM, uPA, MMP-9, and VEGF. Human clinical specimen analysis supported the in vitro and in vivo findings. To our knowledge, this is first report that the cross-talk between Syk and Lck regulates H/R-induced breast cancer progression and further suggests that Syk may act as potential therapeutic target for the treatment of breast cancer.
National Center for Cell Science, Pune 411 007, India.
Goutam
G
Chakraborty
Hema
H
Rangaswami
Shalini
S
Jain
Gopal C
GC
Kundu
D000818:Animals; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology*; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D018450:Disease Progression; D006801:Humans; D000860:Hypoxia; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000378:metabolism*; D015674:Mammary Neoplasms, Animal / Q000378:metabolism / Q000473:pathology*; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D009368:Neoplasm Transplantation; D009389:Neovascularization, Pathologic; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D016329:Sp1 Transcription Factor / Q000378:metabolism; D000072377:Syk Kinase; D013997:Time Factors; D014162:Transfection; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
D047908:Intracellular Signaling Peptides and Proteins; D016329:Sp1 Transcription Factor; D042461:Vascular Endothelial Growth Factor A; D004247:DNA; D011505:Protein-Tyrosine Kinases; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); C000606896:SYK protein, human; D000072377:Syk Kinase; C000606897:Syk protein, mouse; D014568:Urokinase-Type Plasminogen Activator; D020780:Matrix Metalloproteinase 9