Schedule-dependent inhibition of T-cell lymphoma cells by cotreatment with the mTOR inhibitor everolimus and anticancer drugs.
OBJECTIVE
Everolimus (RAD001) is a novel mammalian target of rapamycin (mTOR) inhibitor, and anti-proliferative activity in various malignancies has been reported. This study evaluated the anti-tumor effects and schedule-dependent synergism of everolimus in combination with other chemotherapeutic agents in T-cell lymphoma cell lines.


METHODS
Human T-cell lymphoma cell lines Hut-78 and Jurkat were treated with increasing doses of everolimus, alone or in combination with doxorubicin, etoposide, vincristine, or bortezomib, using different dosing schedules. Anti-tumor effects were measured by assays for cell proliferation, apoptosis, and cell cycle distribution. Drug interactions were determined by median effect analysis.


RESULTS
Exposure to everolimus alone induced G1 phase cell cycle arrest without significant apoptosis. With certain dosing schedules, everolimus showed synergism with doxorubicin, etoposide, and bortezomib, but antagonism with vincristine. Cytotoxic synergism was observed following cotreatment with doxorubicin and everolimus, bortezomib and everolimus, doxorubicin followed by everolimus, and bortezomib followed by everolimus. By contrast, cell exposure to everolimus followed by doxorubicin or followed by bortezomib resulted in antagonistic effects. Sequential exposure to doxorubicin or bortezomib followed by everolimus effectively prevented potential negative interactions, and resulted in drug synergism. Drug combination synergisms or antagonisms were associated with variable effects on the cell cycle distribution.


CONCLUSIONS
Everolimus effectively inhibited the growth of T-cell lymphoma cells in vitro. Specific schedule-dependent combinations of everolimus with other anti-tumor agents which avoid potential drug antagonism and produce effective synergism may lead to clinically effective treatments for T-cell lymphoma.
Huang
Jia-Jia
JJ
Department of Medical Oncology, Cancer Center, Sun Yat-sen University, 651, Dongfeng Road East, Guangzhou, Guangdong 510060, People's Republic of China.
Li
Zhi-Ming
ZM
Huang
Ying
Y
Huang
Yan
Y
Tian
Ying
Y
He
Xue-Xin
XX
Xiao
Jian
J
Lin
Tong-Yu
TY
D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001897:Boronic Acids / Q000494:pharmacology; D000069286:Bortezomib; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000494:pharmacology; D004357:Drug Synergism; D005047:Etoposide / Q000494:pharmacology; D000068338:Everolimus; D006801:Humans; D019169:Jurkat Cells; D016399:Lymphoma, T-Cell / Q000201:enzymology* / Q000473:pathology; D051059:PTEN Phosphohydrolase / Q000378:metabolism; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011719:Pyrazines / Q000494:pharmacology; D020123:Sirolimus / Q000031:analogs & derivatives / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013997:Time Factors; D014750:Vincristine / Q000494:pharmacology
D000903:Antibiotics, Antineoplastic; D001897:Boronic Acids; D047428:Protein Kinase Inhibitors; D011719:Pyrazines; D014750:Vincristine; D000069286:Bortezomib; D005047:Etoposide; D004317:Doxorubicin; D000068338:Everolimus; C546842:MTOR protein, human; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human; D020123:Sirolimus