Berberine these possibilities but, ultimately, the proof must come in vivo and eventually in patients. These data also raise several unanswered questions and potential future directions. The in vivo experiments were performed in a single cell line known to harbor some sensitivity to rapamycin. It would be valuable to conduct tumor growth experiments in models with known resistance to either rapamycin or enzastaurin to determine whether antitumor efficacy would be observed. Furthermore, the current data demonstrate effects on angiogenesis, proliferation, and apoptosis, however, alternative mechanisms of cell death, such as autophagy, may also be relevant, especially considering the role of mTOR as a negative clopidogrel 120202-66-6 regulator of autophagy.15 Takeuchi et al16 have demonstrated in malignant glioma cells resistant to rapamycin that autophagy is augmented by the addition of a phosphoinositide 3 kinase inhibitor or UCN 01. The latter agent is similar but less selective than enzastaurin, suggesting that parallel mechanisms are operational when rapamycin and enzastaurin are combined.
This study therefore supports further development of enzastaurin and rapamycin in SCCHN, especially given the lack of available noncytotoxic agents in this disease. We have taurine 107-35-7 demonstrated efficacy in cell lines and tumor shrinkage in vivo highlighting the potential utility of this combination. The mechanisms underlying these effects still need to be elucidated but cannot be explained by Akt inhibition. Because mTOR is a pleiotropic protein and enzastaurin inhibits multiple kinases, there are numerous possible explanations and likely multiple factors that account for the observed efficacy. Furthermore, there are other tumor types that might also benefit from this combined approach especially where either mTOR inhibitors or enzastaurin have demonstrated activity such as lymphoma, renal cell carcinoma, or glioblastoma multiforme. Given the fact that both enzastaurin and mTOR inhibitors cabozantinib are available for clinical study, future exploration of this combination is warranted. We used 22 lung cancer cell lines: A549, PC3, PC7, PC9, PC14, LC2/ad, ABC 1, RERF LC KJ, RERF LC MS, RERF LC AI adenocarcinoma cell lines and PC1, PC10, LK2, SQ5, QG56, EBC 1, LC1/sq squamous cell carcinoma cell lines and NCI H69, NCI N231, Lu135, SBC3, MS 1 small cell lung carcinoma cell lines for this study.
In addition, five cell lines comprising H1650, H1975, LC 1F, RERF LC OK and VMRC LCD, were used as the test set for a validation study. A549, NCI H69, NCI N231, H1650 and H1975 were purchased from the American Type Culture Collection, RERF LC KJ, RERF LC AI, RERFLC OK, LC2 ad, SQ5, LC2/Ad, LC1/Sq, LC 1F and MS 1 were obtained from the RIKEN Cell Bank and PC1, PC3, PC7, PC9, PC10 and PC14 were obtained from Immuno Biological Laboratories, RERF LC MS, ABC 1, EBC 1, LK2, QG56 and VMRC LCD were purchased from Health Science Research Resources Bank. Lung cancer cell lines were maintained in RPMI 1640 medium supplemented with 10% fetal bovine serum. Drugs and growth inhibition assay biologic Enzastaurin was kindly provided by Ely Lilly. Growth inhibition was assessed by MTS assay to examine the effect of enzastaurin on lung cancer cell lines. Cell suspensions were seeded into 96 well plates and increasing concentrations.
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