RESUMO
Targeting proteins that are overexpressed in cancer cells is the major strategy of molecular imaging and drug delivery systems. The 67-kDa laminin receptor (67LR), also known as oncofetal antigen, is overexpressed in several types of cancer, including melanoma, multiple myeloma, cervical cancer and bile duct carcinoma. 67LR is involved in tumour growth, tumour metastasis and drug resistance. Green tea polyphenol (-)-epigallocatechin-3-O-gallate (EGCG) directly binds to cell-surface 67LR and induces apoptosis through the protein kinase B (Akt)/endothelial nitric oxide synthase/nitric oxide/cyclic GMP (cGMP) axis. Here we report the optimum hydroxyl group for the utilization of EGCG as a novel fluorescent EGCG-mimic imaging probe based on 67LR agonist characters, including Akt activation and inhibitory effect on viable cell number in cancer cells. 67LR specific targeting is unambiguously confirmed with the use of a non-labelled EGCG competitive assay and 67LR knockdown. Importantly, this probe strongly binds to multiple myeloma cells compared with its binding to normal cells.
Assuntos
Anticarcinógenos/farmacologia , Antioxidantes/farmacologia , Catequina/análogos & derivados , Mieloma Múltiplo/metabolismo , Receptores de Laminina/metabolismo , Animais , Catequina/química , Catequina/farmacologia , Linhagem Celular Tumoral , Fluorescência , Técnicas de Silenciamento de Genes , Humanos , Camundongos , Mieloma Múltiplo/genética , Ligação Proteica , Proteínas Proto-Oncogênicas c-akt/metabolismo , Receptores de Laminina/agonistas , Receptores de Laminina/genética , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genéticaRESUMO
Green tea polyphenol (-)-epigallocatechin-3-O-gallate (EGCG) has been attributed to the activation of its cell surface sensing receptor 67 kDa laminin receptor (67LR). However, the action of EGCG to activate 67LR remains unknown. Here we show that EGCG undergoes oligomer formation on its surface receptor 67LR.
Assuntos
Antineoplásicos/farmacologia , Antioxidantes/farmacologia , Catequina/análogos & derivados , Receptores de Laminina/metabolismo , Chá/química , Antineoplásicos/química , Antineoplásicos/metabolismo , Antioxidantes/química , Antioxidantes/metabolismo , Catequina/antagonistas & inibidores , Catequina/química , Catequina/farmacologia , Morte Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Células Hep G2 , Humanos , Estrutura Molecular , Peptídeos/química , Peptídeos/farmacologia , Receptores de Laminina/química , Ressonância de Plasmônio de Superfície , TermodinâmicaRESUMO
(-)-Epigallocatechin-3-O-gallate (EGCG), a polyphenol in green tea, induces apoptosis in acute myeloid leukemia (AML) cells without affecting normal cells. In this study, we observed that cGMP acts as a cell death mediator of the EGCG-induced anti-AML effect through acid sphingomyelinase activation. EGCG activated the Akt/eNOS axis, a well-known mechanism in vascular cGMP upregulation. We also observed that a major cGMP negative regulator, phosphodiesterase 5, was overexpressed in AML cells, and PDE5 inhibitor, an anti-erectile dysfunction drug, synergistically enhanced the anti-AML effect of EGCG. This combination regimen killed AML cells via overexpressed 67-kDa laminin receptors.
Assuntos
Apoptose/efeitos dos fármacos , Catequina/análogos & derivados , Regulação Leucêmica da Expressão Gênica/efeitos dos fármacos , Inibidores da Fosfodiesterase 5/farmacologia , Receptores de Laminina/genética , Catequina/farmacologia , GMP Cíclico/metabolismo , Nucleotídeo Cíclico Fosfodiesterase do Tipo 5/genética , Nucleotídeo Cíclico Fosfodiesterase do Tipo 5/metabolismo , Sinergismo Farmacológico , Ativação Enzimática/efeitos dos fármacos , Células HL-60 , Humanos , Leucemia Mieloide Aguda/tratamento farmacológico , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/metabolismo , Leucemia Mieloide Aguda/patologia , Óxido Nítrico Sintase Tipo III/genética , Óxido Nítrico Sintase Tipo III/metabolismo , Proteína Oncogênica v-akt/genética , Proteína Oncogênica v-akt/metabolismo , Cultura Primária de Células , Receptores de Laminina/agonistas , Receptores de Laminina/metabolismo , Transdução de Sinais , Esfingomielina Fosfodiesterase/genética , Esfingomielina Fosfodiesterase/metabolismoRESUMO
The 67-kDa laminin receptor (67LR) is a laminin-binding protein overexpressed in various types of cancer, including bile duct carcinoma, colorectal carcinoma, cervical cancer, and breast carcinoma. 67LR plays a vital role in growth and metastasis of tumor cells and resistance to chemotherapy. Here, we show that 67LR functions as a cancer-specific death receptor. In this cell death receptor pathway, cGMP initiated cancer-specific cell death by activating the PKCδ/acid sphingomyelinase (PKCδ/ASM) pathway. Furthermore, upregulation of cGMP was a rate-determining process of 67LR-dependent cell death induced by the green tea polyphenol (-)-epigallocatechin-3-O-gallate (EGCG), a natural ligand of 67LR. We found that phosphodiesterase 5 (PDE5), a negative regulator of cGMP, was abnormally expressed in multiple cancers and attenuated 67LR-mediated cell death. Vardenafil, a PDE5 inhibitor that is used to treat erectile dysfunction, significantly potentiated the EGCG-activated 67LR-dependent apoptosis without affecting normal cells and prolonged the survival time in a mouse xenograft model. These results suggest that PDE5 inhibitors could be used to elevate cGMP levels to induce 67LR-mediated, cancer-specific cell death.
