title: Pyrimethamine sensitizes pituitary adenomas cells to temozolomide through cathepsin B-dependent and caspase-dependent apoptotic pathways.
abstract: Invasive pituitary adenomas (PAs) are generally refractory to conventional therapy and salvage treatment with temozolomide (TMZ). In addition to antiprotozoan effects, pyrimethamine (PYR) has recently shown its strong antitumor activity as an antineoplastic agent or in combination with TMZ in metastatic melanoma cells. In this study, the effects of TMZ, PYR or TMZ/PYR combination on rat/mouse PA cell lines αT3-1, GH3, MMQ and ATt-20 as well as GH3 xenograft tumor model were evaluated. TMZ/PYR combination synergistically inhibited proliferation, invasion and induced apoptosis of these PA cell lines in vitro. Strikingly, combination treatment with TMZ and PYR produced synergistic antitumor activity and enhanced the survival rate of GH3 xenograft tumor models without increasing systemic side effects. In addition, TMZ/PYR induced cell cycle arrest, increased DNA damage, upregulated the expression of cathepsin B, BAX, cleaved PARP and phosphorylated histone H2AX as well as elevated caspase3/7, 8 and 9 activities. The decreased expression of Bcl-2, MMP-2 and MMP-9 alone with cytochrome c release from mitochondria into the cytosol was also observed in the TMZ/PYR combination group. The increase in cell apoptosis due to combination with PYR was rescued by leucovorin. These data suggest that PYR may enhance the efficacy of TMZ via triggering both cathepsin B-dependent and caspase-dependent apoptotic pathways. Therefore, combination of PYR and TMZ may provide a novel regimen for invasive PAs refractory to standard therapy and TMZ.
authors.affiliation: Department of Neurosurgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China.
authors.forename: Congxin
authors.initials: C
authors.lastname: Dai
authors.forename: Bo
authors.initials: B
authors.lastname: Zhang
authors.forename: Xiaohai
authors.initials: X
authors.lastname: Liu
authors.forename: Kai
authors.initials: K
authors.lastname: Guo
authors.forename: Sihai
authors.initials: S
authors.lastname: Ma
authors.forename: Feng
authors.initials: F
authors.lastname: Cai
authors.forename: Yakun
authors.initials: Y
authors.lastname: Yang
authors.forename: Yong
authors.initials: Y
authors.lastname: Yao
authors.forename: Ming
authors.initials: M
authors.lastname: Feng
authors.forename: Xinjie
authors.initials: X
authors.lastname: Bao
authors.forename: Kan
authors.initials: K
authors.lastname: Deng
authors.forename: Yonghui
authors.initials: Y
authors.lastname: Jiao
authors.forename: Zhenqing
authors.initials: Z
authors.lastname: Wei
authors.forename: Wei
authors.initials: W
authors.lastname: Junji
authors.forename: Bing
authors.initials: B
authors.lastname: Xing
authors.forename: Wei
authors.initials: W
authors.lastname: Lian
authors.forename: Renzhi
authors.initials: R
authors.lastname: Wang
mesh_terms: D000818:Animals; D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D053179:Caspase 7 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D002401:Cathepsin B / Q000096:biosynthesis / Q000378:metabolism*; D059447:Cell Cycle Checkpoints / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D045304:Cytochromes c / Q000378:metabolism; D004249:DNA Damage; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004357:Drug Synergism; D005260:Female; D005493:Folic Acid Antagonists / Q000494:pharmacology; D006657:Histones / Q000378:metabolism; D002955:Leucovorin / Q000494:pharmacology; D020778:Matrix Metalloproteinase 2 / Q000096:biosynthesis; D020780:Matrix Metalloproteinase 9 / Q000096:biosynthesis; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D008928:Mitochondria / Q000187:drug effects; D009361:Neoplasm Invasiveness; D009368:Neoplasm Transplantation; D010766:Phosphorylation / Q000187:drug effects; D010911:Pituitary Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D011739:Pyrimethamine / Q000494:pharmacology*; D051381:Rats; D000077204:Temozolomide; D015854:Up-Regulation / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays; D051028:bcl-2-Associated X Protein / Q000096:biosynthesis
chemical_list: D018906:Antineoplastic Agents, Alkylating; D053148:Caspase 3; D053179:Caspase 7; D053453:Caspase 9; D002401:Cathepsin B; D045304:Cytochromes c; D003606:Dacarbazine; D005493:Folic Acid Antagonists; D006657:Histones; D002955:Leucovorin; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D019253:Proto-Oncogene Proteins c-bcl-2; D011739:Pyrimethamine; D000077204:Temozolomide; D051028:bcl-2-Associated X Protein; C052617:Bcl2 protein, mouse; C499321:Parp1 protein, mouse; C522362:Mmp2 protein, mouse; C501830:Mmp9 protein, mouse; C475961:gamma-H2AX protein, mouse
keywords: folate metabolism; invasive pituitary adenomas; pyrimethamine; refractory; temozolomide