Combined inhibition of PLC{gamma}-1 and c-Src abrogates epidermal growth factor receptor-mediated head and neck squamous cell carcinoma invasion.
OBJECTIVE
Mortality from head and neck squamous cell carcinoma (HNSCC) is usually associated with locoregional invasion of the tumor into vital organs, including the airway. Understanding the signaling mechanisms that abrogate HNSCC invasion may reveal novel therapeutic targets for intervention. The purpose of this study was to investigate the efficacy of combined inhibition of c-Src and PLCgamma-1 in the abrogation of HNSCC invasion.


METHODS
PLCgamma-1 and c-Src inhibition was achieved by a combination of small molecule inhibitors and dominant negative approaches. The effect of inhibition of PLCgamma-1 and c-Src on invasion of HNSCC cells was assessed in an in vitro Matrigel-coated transwell invasion assay. In addition, the immunoprecipitation reactions and in silico database mining was used to examine the interactions between PLCgamma-1 and c-Src.


RESULTS
Here, we show that inhibition of PLCgamma-1 or c-Src with the PLC inhibitor U73122 or the Src family inhibitor AZD0530 or using dominant-negative constructs attenuated epidermal growth factor (EGF)-stimulated HNSCC invasion. Furthermore, EGF stimulation increased the association between PLCgamma-1 and c-Src in HNSCC cells. Combined inhibition of PLCgamma-1 and c-Src resulted in further attenuation of HNSCC cell invasion in vitro.


CONCLUSIONS
These cumulative results suggest that PLCgamma-1 and c-Src activation contribute to HNSCC invasion downstream of EGF receptor and that targeting these pathways may be a novel strategy to prevent tumor invasion in HNSCC.
Nozawa
Hiroshi
H
Department of Oral and Maxillofacial Surgery, National Defense Medical College, Tokorozawa, Saitama, Japan.
Howell
Gina
G
Suzuki
Shinsuke
S
Zhang
Qing
Q
Qi
Yanjun
Y
Klein-Seetharaman
Judith
J
Wells
Alan
A
Grandis
Jennifer R
JR
Thomas
Sufi M
SM
D000970:Antineoplastic Agents / Q000494:pharmacology*; D002294:Carcinoma, Squamous Cell / Q000378:metabolism*; D045744:Cell Line, Tumor; D003094:Collagen / Q000737:chemistry; D004338:Drug Combinations; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066246:ErbB Receptors / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic; D005799:Genes, Dominant; D006258:Head and Neck Neoplasms / Q000378:metabolism*; D006801:Humans; D007797:Laminin / Q000737:chemistry; D008954:Models, Biological; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D051966:Phospholipase C gamma / Q000037:antagonists & inhibitors*; D011509:Proteoglycans / Q000737:chemistry; D019061:src-Family Kinases / Q000037:antagonists & inhibitors*
D000970:Antineoplastic Agents; D004338:Drug Combinations; D004791:Enzyme Inhibitors; D007797:Laminin; D011509:Proteoglycans; C059485:matrigel; D003094:Collagen; D066246:ErbB Receptors; D019061:src-Family Kinases; D051966:Phospholipase C gamma