Targeting Mammalian Target of Rapamycin Synergistically Enhances Chemotherapy-Induced Cytotoxicity in Breast Cancer Cells

Purpose: The serine-threonine kinase mammalian target of rapamycin has emerged as a potential target for cancer therapy. Rapamycin and rapamycin analogs are undergoing clinical trials and have induced clinical responses in a subgroup of patients. Rapamycin has also been reported to enhance the efficacy of several cytotoxic agents. The aim of this study was to determine the nature of the interactions between rapamycin and chemotherapeutic agents used as first- and second-line agents against breast cancer. Experimental Design: We performed a multiple drug effect/combination index isobologram analysis in cells sensitive and resistant to rapamycin alone in vitro, and we evaluated the in vivo efficacy of combination therapy in a rapamycin-sensitive model. Results: In vitro, synergistic interactions were observed in combinations with paclitaxel, carboplatin, and vinorelbine. Additive effects were observed in combinations with doxorubicin and gemcitabine. Rapamycin dramatically enhanced paclitaxel- and carboplatin-induced apoptosis. This effect was sequence dependent and mediated at least partly through caspase activation. Furthermore, rapamycin enhanced chemosensitivity to paclitaxel and carboplatin in HER2/neu-overexpressing cells, suggesting a potential approach to these poorly behaving tumors. Cell lines that are resistant to the growth-inhibitory effect of rapamycin were also resistant to rapamycin-mediated chemosensitization. In vivo, rapamycin combined with paclitaxel resulted in a significant reduction in tumor volume compared with either agent alone in rapamycin-sensitive tumors. Conclusions: Rapamycin potentiates the cytotoxicity of selected chemotherapeutic agents in cell lines sensitive to the effects of rapamycin due to aberrations in the phosphatidylinositol 3′-kinase/Akt pathway, suggesting that combination therapy may be effective in patients selected for aberrations in this pathway.

[1]  S. Lowe,et al.  Survival signalling by Akt and eIF4E in oncogenesis and cancer therapy , 2004, Nature.

[2]  G. Mills,et al.  Determinants of Rapamycin Sensitivity in Breast Cancer Cells , 2004, Clinical Cancer Research.

[3]  A. Scovassi,et al.  Poly(ADP-ribose) polymerase-1 cleavage during apoptosis: An update , 2002, Apoptosis.

[4]  M. Kuo,et al.  Cell cycle G2/M arrest and activation of cyclin-dependent kinases associated with low-dose paclitaxel-induced sub-G1 apoptosis , 2004, Apoptosis.

[5]  M. Carroll,et al.  Survival of acute myeloid leukemia cells requires PI3 kinase activation. , 2003, Blood.

[6]  Shile Huang,et al.  Sustained activation of the JNK cascade and rapamycin-induced apoptosis are suppressed by p53/p21(Cip1). , 2003, Molecular cell.

[7]  A. Adjei,et al.  Principles of chemotherapy , 2006 .

[8]  Ping Zhang,et al.  Insulin-like growth factor-I inhibits progesterone receptor expression in breast cancer cells via the phosphatidylinositol 3-kinase/Akt/mammalian target of rapamycin pathway: progesterone receptor as a potential indicator of growth factor activity in breast cancer. , 2003, Molecular endocrinology.

[9]  G. Mills,et al.  Paclitaxel induces inactivation of p70 S6 kinase and phosphorylation of Thr421 and Ser424 via multiple signaling pathways in mitosis1 , 2003, Oncogene.

[10]  W. Friedrichs,et al.  Inhibitors of mTOR reverse doxorubicin resistance conferred by PTEN status in prostate cancer cells. , 2002, Cancer research.

[11]  G. Hortobagyi,et al.  Enhanced sensitization to taxol-induced apoptosis by herceptin pretreatment in ErbB2-overexpressing breast cancer cells. , 2002, Cancer research.

[12]  F. Meric,et al.  Translation initiation in cancer: a novel target for therapy. , 2002, Molecular cancer therapeutics.

[13]  K. Inoki,et al.  TSC2 is phosphorylated and inhibited by Akt and suppresses mTOR signalling , 2002, Nature Cell Biology.

[14]  L. Shaw,et al.  Integrin (α6β4) regulation of eIF-4E activity and VEGF translation , 2002, The Journal of Cell Biology.

[15]  S. Bodine,et al.  Control of Ser2448 Phosphorylation in the Mammalian Target of Rapamycin by Insulin and Skeletal Muscle Load* , 2002, The Journal of Biological Chemistry.

[16]  G Milano,et al.  Influence of epidermal growth factor receptor (EGFR), p53 and intrinsic MAP kinase pathway status of tumour cells on the antiproliferative effect of ZD1839 (‘Iressa’) , 2002, British Journal of Cancer.

[17]  A. Gingras,et al.  Translational Control of Cell Fate: Availability of Phosphorylation Sites on Translational Repressor 4E-BP1 Governs Its Proapoptotic Potency , 2002, Molecular and Cellular Biology.

[18]  G. Hortobagyi,et al.  HER2/neu in the management of invasive breast cancer. , 2002, Journal of the American College of Surgeons.

[19]  C. Proud,et al.  Caspase Cleavage of Initiation Factor 4E-Binding Protein 1 Yields a Dominant Inhibitor of Cap-Dependent Translation and Reveals a Novel Regulatory Motif , 2002, Molecular and Cellular Biology.

[20]  L. Helman,et al.  Effect of insulin-like growth factor II on protecting myoblast cells against cisplatin-induced apoptosis through p70 S6 kinase pathway. , 2002, Neoplasia.

[21]  L. Shaw,et al.  Integrin (alpha 6 beta 4) regulation of eIF-4E activity and VEGF translation: a survival mechanism for carcinoma cells. , 2002, The Journal of cell biology.

[22]  G. Mills,et al.  Linking molecular therapeutics to molecular diagnostics: Inhibition of the FRAP/RAFT/TOR component of the PI3K pathway preferentially blocks PTEN mutant cells in vitro and in vivo , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[23]  Hong Wu,et al.  Enhanced sensitivity of PTEN-deficient tumors to inhibition of FRAP/mTOR , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[24]  J. Blenis,et al.  An inhibitor of mTOR reduces neoplasia and normalizes p70/S6 kinase activity in Pten+/− mice , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[25]  M. Mann,et al.  p70S6 kinase signals cell survival as well as growth, inactivating the pro-apoptotic molecule BAD , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[26]  Shile Huang,et al.  p53/p21(CIP1) cooperate in enforcing rapamycin-induced G(1) arrest and determine the cellular response to rapamycin. , 2001, Cancer research.

[27]  A. Rustgi,et al.  Paclitaxel induces prolonged activation of the Ras/MEK/ERK pathway independently of activating the programmed cell death machinery. , 2001, The Journal of biological chemistry.

[28]  B. Geoerger,et al.  Antitumor activity of the rapamycin analog CCI-779 in human primitive neuroectodermal tumor/medulloblastoma models as single agent and in combination chemotherapy. , 2001, Cancer research.

[29]  P. Houghton,et al.  p 53 / p 21 CIP 1 Cooperate in Enforcing Rapamycin-induced G 1 Arrest and Determine the Cellular Response to Rapamycin 1 , 2001 .

[30]  Michael A Davies,et al.  MMAC1/PTEN inhibits cell growth and induces chemosensitivity to doxorubicin in human bladder cancer cells , 2000, Oncogene.

[31]  Christine C. Hudson,et al.  A direct linkage between the phosphoinositide 3-kinase-AKT signaling pathway and the mammalian target of rapamycin in mitogen-stimulated and transformed cells. , 2000, Cancer research.

[32]  M. Hung,et al.  HER-2/neu Blocks Tumor Necrosis Factor-induced Apoptosis via the Akt/NF-κB Pathway* , 2000, The Journal of Biological Chemistry.

[33]  M. C. Hu,et al.  HER-2/neu blocks tumor necrosis factor-induced apoptosis via the Akt/NF-kappaB pathway. , 2000, The Journal of biological chemistry.

[34]  D. Henley,et al.  Microtubule Dysfunction Induced by Paclitaxel Initiates Apoptosis through Both c-Jun N-terminal Kinase (JNK)-dependent and -Independent Pathways in Ovarian Cancer Cells* , 1999, The Journal of Biological Chemistry.

[35]  Linda N. Liu,et al.  Rapamycin causes poorly reversible inhibition of mTOR and induces p53-independent apoptosis in human rhabdomyosarcoma cells. , 1999, Cancer research.

[36]  J. Lawrence,et al.  Attenuation of Mammalian Target of Rapamycin Activity by Increased cAMP in 3T3-L1 Adipocytes* , 1998, The Journal of Biological Chemistry.

[37]  J. Ting,et al.  Paclitaxel (Taxol)-induced Gene Expression and Cell Death Are Both Mediated by the Activation of c-Jun NH2-terminal Kinase (JNK/SAPK)* , 1998, The Journal of Biological Chemistry.

[38]  R. Perona,et al.  Cisplatin induces a persistent activation of JNK that is related to cell death , 1998, Oncogene.

[39]  N. Sonenberg,et al.  Translational control of programmed cell death: eukaryotic translation initiation factor 4E blocks apoptosis in growth-factor-restricted fibroblasts with physiologically expressed or deregulated Myc , 1996, Molecular and cellular biology.

[40]  M. Hung,et al.  Overexpression of c-erbB-2/neu in breast cancer cells confers increased resistance to Taxol via mdr-1-independent mechanisms. , 1996, Oncogene.

[41]  G. Mills,et al.  Rapamycin enhances apoptosis and increases sensitivity to cisplatin in vitro. , 1995, Cancer research.

[42]  S. Sehgal,et al.  Activity of rapamycin (AY-22,989) against transplanted tumors. , 1984, The Journal of antibiotics.

[43]  T. Chou,et al.  Quantitative analysis of dose-effect relationships: the combined effects of multiple drugs or enzyme inhibitors. , 1984, Advances in enzyme regulation.

[44]  J. Douros,et al.  New antitumor substances of natural origin. , 1981, Cancer treatment reviews.

[45]  S. Sehgal,et al.  Rapamycin (AY-22,989), a new antifungal antibiotic. II. Fermentation, isolation and characterization. , 1975, The Journal of antibiotics.

[46]  S. Sehgal,et al.  Rapamycin (AY-22,989), a new antifungal antibiotic. I. Taxonomy of the producing streptomycete and isolation of the active principle. , 1975, The Journal of antibiotics.

[47]  C. Keele,et al.  The Principles of Chemotherapy , 1952, Postgraduate medical journal.