Pyrimethamine (2,4-Diamino-5-<i>p</i>-chlorophenyl-6-ethylpyrimidine) Induces Apoptosis of Freshly Isolated Human T Lymphocytes, Bypassing CD95/Fas Molecule but Involving Its Intrinsic Pathway

Pierdominici, Marina; Giammarioli, Anna Maria; Gambardella, Lucrezia; Felice, Marco De; Quinti, Isabella; Iacobini, Metello; Carbonari, Maurizio; Malorni, Walter; Giovannetti, Antonello

doi:10.1124/jpet.105.086736

Cited by 17 publications

(19 citation statements)

References 32 publications

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“…In fact, pyrimethamine was able to induce upstream caspase activation (caspase-8), bypassing CD95/ Fas engagement, similarly to what we had previously observed in activated lymphocytes from a patient with a lymphoproliferative syndrome (16). This is noteworthy considering that the melanoma cell lines used in this study were shown to defy CD95-mediated apoptosis in vitro.…”

Section: Discussionsupporting

confidence: 59%

“…According to what was observed in activated lymphocytes (16), this effect did not require CD95/Fas engagement, as shown by experiments performed with a specific mAb blocking CD95/Fas. However, we cannot rule out the possibility that a ligand-independent aggregation of the death receptor and a recruitment of death-inducing signaling complex could occur, as shown with some oxidizing agents or bile acids (33,34).…”

Section: Discussionmentioning

confidence: 80%

“…In addition to its antiprotozoal effects, pyrimethamine may exert immunomodulating activities, including the induction of peripheral blood lymphocyte apoptosis (12)(13)(14)(15). We showed that this drug induces apoptosis of activated lymphocytes via a mechanism that brings into play the upstream caspases (16). However, although the primary target of pyrimethamine is represented by the caspase-8-driven cascade, this drug also acts on mitochondria.…”

Section: Introductionmentioning

confidence: 92%

“…Caspase-8 and caspase-9 activities were assayed by using the CaspGLOW fluorescein active caspase staining kit (MBL), following the manufacturer's instruction, as previously described (16). Western blot was also performed as described before (10).…”

Section: Analytic Cytology Analysesmentioning

confidence: 99%

“…Surface phenotyping and Bcl-2 expression analyses were performed by flow cytometry, as described before (16). The following mAbs were used: anti-CD95 conjugated to FITC (BD Immunocytometry Systems) and anti-Bcl-2-FITC (DAKO).…”

Section: Analytic Cytology Analysesmentioning

confidence: 99%

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Pyrimethamine Induces Apoptosis of Melanoma Cells via a Caspase and Cathepsin Double-Edged Mechanism

et al. 2008

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The unresponsiveness of metastatic melanoma to conventional chemotherapeutic and biological agents is largely due to the development of resistance to apoptosis. Pyrimethamine belongs to the group of antifolate drugs, and in addition to antiprotozoan effects, it exerts a strong proapoptotic activity, which we recently characterized in human T lymphocytes. However, no data regarding pyrimethamine anticancer activity are available thus far. To this end, we examined the in vitro effects of pyrimethamine on apoptosis, cell cycle distribution, and cell proliferation of human metastatic melanoma cell lines. The in vivo antitumor potential of pyrimethamine was evaluated in a severe combined immunodeficiency (SCID) mouse xenotransplantation model. Our data indicate that pyrimethamine, when used at a clinically relevant concentration, induced apoptosis in metastatic melanoma cells via the activation of the cathepsin B and the caspase cascade (i.e., caspase-8 and caspase-9) and subsequent mitochondrial depolarization. This occurred independently from CD95/Fas engagement. Moreover, pyrimethamine induced a marked inhibition of cell growth and an S-phase cell cycle arrest. Results obtained in SCID mice, injected s.c. with metastatic melanoma cells and treated with pyrimethamine, indicated a significant inhibitory effect on tumor growth. In conclusion, our results suggest that pyrimethamine-induced apoptosis may be considered as a multifaceted process, in which different inducers or regulators of apoptosis are simultaneously implicated, thus permitting death defects of melanoma cells to be bypassed or overcome. On these bases, we hypothesize that pyrimethamine could represent an interesting candidate for the treatment of metastatic melanoma.

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Section: Discussionsupporting

confidence: 59%

Section: Discussionmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 92%

Section: Analytic Cytology Analysesmentioning

confidence: 99%

Section: Analytic Cytology Analysesmentioning

confidence: 99%

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Pyrimethamine Induces Apoptosis of Melanoma Cells via a Caspase and Cathepsin Double-Edged Mechanism

et al. 2008

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Pyrimethamine treatment does not ameliorate lymphoproliferation or autoimmune disease in MRL/lpr−/− mice or in patients with autoimmune lymphoproliferative syndrome

et al. 2007

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Autoimmune lymphoproliferative syndrome (ALPS) is an inherited disorder of lymphocyte apoptosis leading to childhood onset of marked lymphadenopathy, hepatosplenomegaly, autoimmune cytopenias, and increased risk of lymphoma. Most cases are associated with heterozygous mutations in the gene encoding Fas protein. Prolonged use of immunosuppressive drugs that do ameliorate its autoimmune complications fail to consistently lessen lymphoproliferation in ALPS. A case series had described children with ALPS, whose spleens (SPL) and lymph nodes decreased in size when treated weekly with pyrimethamine and sulfadoxine; parallel in vitro studies showed only pyrimethamine to promote apoptosis. On the basis of that experience, we undertook additional in vitro lymphocyte apoptosis assays, and measured SPL weights, lymphocyte numbers, and immunophenotypes in Fas-deficient MRL/lpr2/2 mice to gain further insights into the utility of combined pyrimethamine/sulfadoxine or pyrimethamine alone. Moreover, seven children with ALPS enrolled in a study of escalating dose of pyrimethamine alone given twice weekly for 12 weeks to determine if their lymphadenopathy and/or splenomegaly would diminish, as assessed by standardized computerized tomography. Neither pyrimethamine alone or with sulfadoxine in the MRL/lpr2/2 mice, nor pyrimethamine alone in ALPS patients proved efficacious. We conclude that these drugs do not warrant further use empirically or as part of clinical trials in ALPS Type Ia as a lympholytic agent. Am.

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Analyses of T cell phenotype and function reveal an altered T cell homeostasis in systemic sclerosis

Giovannetti

Rosato

Renzi

et al. 2010

Clinical Immunology

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Pyrimethamine (2,4-Diamino-5-p-chlorophenyl-6-ethylpyrimidine) Induces Apoptosis of Freshly Isolated Human T Lymphocytes, Bypassing CD95/Fas Molecule but Involving Its Intrinsic Pathway

Cited by 17 publications

References 32 publications

Pyrimethamine Induces Apoptosis of Melanoma Cells via a Caspase and Cathepsin Double-Edged Mechanism

Pyrimethamine Induces Apoptosis of Melanoma Cells via a Caspase and Cathepsin Double-Edged Mechanism

Pyrimethamine treatment does not ameliorate lymphoproliferation or autoimmune disease in MRL/lpr−/− mice or in patients with autoimmune lymphoproliferative syndrome

Analyses of T cell phenotype and function reveal an altered T cell homeostasis in systemic sclerosis

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