title: The dual PI3K/mTOR inhibitor PI-103 promotes immunosuppression, in vivo tumor growth and increases survival of sorafenib-treated melanoma cells.
abstract: Melanoma is the most lethal human skin cancer. If metastatic, it becomes very aggressive and resistant to standard modalities of anticancer treatment. During the last 10 years, several therapeutic strategies have been tested including the use of single and combined small drugs. Experimental results indicate that RAS and PI3K pathways are important for the development and maintenance of melanoma. In this study, we assessed the in vitro and in vivo inhibition potential of PI-103, a PI3K (p110alpha)/mTOR inhibitor and sorafenib, a BRAF inhibitor, as single agents and in combination in primary melanoma cell lines. Although PI-103 and sorafenib inhibited melanoma in vitro cell proliferation and viability, the inhibition of RAS pathway appeared to be more effective. The combination of the two agents in in vitro showed a synergistic effect inhibiting RAS and PI3K pathways in a cell line dependent manner. However, no cooperative effect was observed in blocking in vivo tumor growth in immunocompetent mice. In contrary to the expected, the data indicate that PI-103 induced immunosuppression promoting in vivo tumor growth and inhibiting apoptosis. Furthermore, in vitro studies examining the effects of the PI3K/mTOR inhibitor in tumor derived cell lines indicated that PI-103 induced the anti-apoptotic BH3 family proteins Mcl1, Bcl2 and Bcl(xL) favoring, the in vitro survival of sorafenib treated melanoma cells. These data certainly makes an argument for investigating unexpected effects of rational drug combinations on immunocompetent animal models prior to conducting clinical studies.
authors.affiliation: Medical Oncology Research Program, Vall d'Hebron Research Institute, Vall d'Hebron Institute of Oncology (VHIO), Vall d'Hebron Hospital, Barcelona 08035, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: López-Fauqued
authors.forename: Rosa
authors.initials: R
authors.lastname: Gil
authors.forename: Judit
authors.initials: J
authors.lastname: Grueso
authors.forename: Javier
authors.initials: J
authors.lastname: Hernandez-Losa
authors.forename: Anna
authors.initials: A
authors.lastname: Pujol
authors.forename: Teresa
authors.initials: T
authors.lastname: Moliné
authors.forename: Juan A
authors.initials: JA
authors.lastname: Recio
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols; D017209:Apoptosis / Q000187:drug effects; D001557:Benzenesulfonates / Q000494:pharmacology*; D015153:Blotting, Western; D049109:Cell Proliferation; D003114:Colony-Forming Units Assay; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D005663:Furans / Q000494:pharmacology*; D006801:Humans; D007124:Immunoenzyme Techniques; D007165:Immunosuppression Therapy; D036341:Intercellular Signaling Peptides and Proteins / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008297:Male; D008545:Melanoma / Q000276:immunology / Q000401:mortality / Q000473:pathology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009536:Niacinamide / Q000031:analogs & derivatives; D010671:Phenylurea Compounds; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology*; D011743:Pyrimidines / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000077157:Sorafenib; D015996:Survival Rate; D058570:TOR Serine-Threonine Kinases; D014407:Tumor Cells, Cultured; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D001557:Benzenesulfonates; D048049:Extracellular Signal-Regulated MAP Kinases; D005663:Furans; D036341:Intercellular Signaling Peptides and Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009536:Niacinamide; D010671:Phenylurea Compounds; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011725:Pyridines; D011743:Pyrimidines; D012333:RNA, Messenger; D000077157:Sorafenib; D058570:TOR Serine-Threonine Kinases; D018631:ras Proteins; C522973:PI103; C546842:MTOR protein, human; C546843:mTOR protein, mouse