ABSTRACT
OBJECTIVE: To determine how vascular endothelial growth factor C (VEGF-C) affects tumor cell invasion and motility in squamous cell carcinoma of the head and neck (SCCHN). DESIGN: A molecular biology study. The VEGF-C coding sequence was cloned into an expression vector and stably transfected into the SCCHN cell line SCC116 to create the SCC116-VEGFC line. RNA interference (RNAi) was used to block VEGF-C expression. An adenoviral system for expressing VEGF-C RNAi was developed and tested. SETTING: An academic hospital laboratory. MAIN OUTCOME MEASURES: Relative VEGF-C RNA levels were determined by real-time quantitative reverse transcriptase-polymerase chain reaction, and protein expression was evaluated by Western blot. Cellular invasion was evaluated by 24-hour semipermeable membrane transit assay. RESULTS: SCC116-VEGFC cells had markedly increased expression of VEGF-C protein and RNA compared with normal SCC116 controls. SCC116-VEGFC cells produced marked increases in cellular invasion and motility compared with SCC116 cells. Blockade of VEGF-C expression by transfection of a VEGF-C RNAi expression plasmid into both SCC116 and SCC116-VEGFC cells induced a 38% decrease in SCCHN invasion and motility as tested by a semipermeable membrane invasion assay. We developed an adenoviral expression system for VEGF-C RNAi, which also induced a dose-dependent decrease in cellular invasion in the highly invasive DM12 cell line. CONCLUSIONS: These studies demonstrate that intracellular VEGF-C levels modulate in vitro SCCHN motility and invasion. Further work is needed to clarify the specific receptors and signaling pathways that are involved in SCCHN motility. Molecular therapies that inhibit the VEGF-C pathway may have clinical potential in the treatment of lymphatic metastasis in SCCHN.
Subject(s)
Carcinoma, Squamous Cell/metabolism , Carcinoma, Squamous Cell/pathology , Head and Neck Neoplasms/metabolism , Head and Neck Neoplasms/pathology , RNA Interference , Vascular Endothelial Growth Factor C/physiology , Cell Culture Techniques , Cell Line, Tumor , Cell Movement , Humans , Neoplasm Invasiveness , Transduction, GeneticABSTRACT
Celecoxib inhibits proliferation and induces apoptosis in human tumors, but the molecular mechanisms for these processes are poorly understood. In this study, we evaluated the ability of celecoxib to induce toxicity in head and neck squamous cell carcinomas (HNSCC) and explored the relationships between celecoxib-induced cell cycle inhibition and toxicity in HNSCC. Celecoxib inhibited the proliferation of UM-SCC-1 and UM-SCC-17B cells both in vitro and in vivo, accompanied by G(1) phase cell cycle arrest and apoptosis. Celecoxib induced p21(waf1/cip1) at the transcriptional level independent of wild-type p53 function, leading to decreased expression of cyclin D1 and hypophosphorylation of Rb, with subsequent marked downstream decreases in nuclear E2F-1 protein expression and E2F transactivating activity by luciferase reporter assay. Cell cycle phase-specific cytometric sorting showed that celecoxib induced clonogenic toxicity preferentially to cells within the S phase greater than G(1) and G(2) phases. Levels of p21(waf1/cip1) and cyclin D1 protein were reduced in the S phase compared with the G(1) and G(2) phases, suggesting a possible protective role for p21(waf1/cip1) expression in celecoxib toxicity. In conclusion, we show that celecoxib has marked antiproliferative activity against head and neck cancer cells through transcriptional induction of p21(waf1/cip1) and G(1) phase accumulation leading to S phase-specific clonogenic toxicity. We additionally show that a profound inhibition of nuclear E2F function provides a possible mechanism for this S phase-specific toxicity.
Subject(s)
Carcinoma, Squamous Cell/drug therapy , G1 Phase/drug effects , Head and Neck Neoplasms/drug therapy , Pyrazoles/pharmacology , S Phase/drug effects , Sulfonamides/pharmacology , Animals , Apoptosis/drug effects , Carcinoma, Squamous Cell/genetics , Carcinoma, Squamous Cell/metabolism , Carcinoma, Squamous Cell/pathology , Celecoxib , Cell Growth Processes/drug effects , Cyclin-Dependent Kinase Inhibitor p21/biosynthesis , Cyclin-Dependent Kinase Inhibitor p21/genetics , E2F Transcription Factors/antagonists & inhibitors , E2F Transcription Factors/metabolism , Female , Head and Neck Neoplasms/genetics , Head and Neck Neoplasms/metabolism , Head and Neck Neoplasms/pathology , Humans , Mice , Mice, Nude , RNA, Messenger/biosynthesis , RNA, Messenger/genetics , Transcriptional Activation/drug effectsABSTRACT
This study was performed to compare the relative antineoplastic activity of 10 different non-steroidal anti-inflammatory drugs (NSAIDs) in clinical use, and to investigate the underlying mechanisms of this activity in a squamous cell carcinoma of the head and neck model (SCCHN). A standard 5-day MTT assay was used to calculate IC(50) values in UM-SCC-1 cells for 10 NSAIDs, including celecoxib, rofecoxib, sulindac sulfide, sulindac sulfone, indomethacin, ketoprofen, flurbiprofen, naproxen, piroxicam, and aspirin. Celecoxib, a COX-2 specific inhibitor, was by far the most potent NSAID, with an IC(50) of 39.9 +/- 1.1 microM, followed by sulindac sulfide (116.5 +/- 2.34 microM). Celecoxib and sulindac sulfide also induced more activation of caspase-3 than any other NSAID. Cell cycle analysis showed that celecoxib and sulindac sulfide both induced a 3-fold increase in G(1) phase distribution, and this correlated with strong induction of p21(waf1/cip1), inhibition of cyclin D1, and hypophosphorylation of Rb. Celecoxib and sulindac sulfide treatment induced strong downstream inhibition of E2F transactivating activity as determined by a luciferase reporter assay. These data demonstrate the wide range of activity of various NSAID agents, and reveal a mechanism of action through cell cycle inhibition and induction of apoptosis.
Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/pharmacology , Cell Proliferation/drug effects , Cyclin-Dependent Kinase Inhibitor p21/pharmacology , G1 Phase/drug effects , Apoptosis , Celecoxib , E2F Transcription Factors/antagonists & inhibitors , Humans , Pyrazoles/pharmacology , Sulfonamides/pharmacology , Sulindac/analogs & derivatives , Sulindac/pharmacology , Tumor Cells, CulturedABSTRACT
Sulindac sulfide and sulindac sulfone have demonstrated anti-neoplastic and chemo-preventive activity against various human tumors, but few studies have examined the relative effectiveness of these drugs against squamous cell carcinoma of the head and neck (SCCHN). These compounds are metabolites of the nonsteroidal anti-inflammatory drug sulindac and differ in their ability to inhibit cyclooxygenase-2 (COX-2) enzyme function. Sulindac sulfide (the sulindac metabolite with COX-2 inhibitory function) demonstrated strong cell growth inhibition as measured by MTT and growth assays in UM-SCC-1 and SCC-25 cells, while sulindac sulfone had only moderate effect. Growth inhibition by sulindac sulfide was associated with a significant increase in percent G cells and activation of caspase-3. Sulindac sulfide induced expression of p21wafl/cipl in a dose-dependent fashion, decreased cyclin D1 protein levels, and increased Rb hypophosphorylation. p21waf1/cip1 protein levels increased without a significant increase in wild-type p53, suggesting that sulindac sulfide induces a p53-independent pathway regulating p2lwafl/ciP1 protein levels in SCCHN. Sulindac sulfide also induced dose-dependent expression of PPAR-gamma. In contrast, sulindac sulfone did not significantly alter apoptosis, cell cycle distribution or G1 checkpoint protein expression at doses below 200 microM. These results demonstrate the differential activity of sulindac metabolites and support the hypothesis that sulindac sulfide induced perturbations in SCCHN cellular proliferation could be regulated both by p21waf1/cip1-dependent cytostatic and caspase-dependent cytotoxic pathways.
