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Inosine Strongly Enhances Proliferation of Human C32 Melanoma Cells through PLC ‐ PKC ‐ MEK 1/2‐ ERK 1/2 and PI3K Pathways
Author(s) -
Soares Ana Sofia,
Costa Vera Marisa,
Diniz Carmen,
Fresco Paula
Publication year - 2015
Publication title -
basic and clinical pharmacology and toxicology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.805
H-Index - 90
eISSN - 1742-7843
pISSN - 1742-7835
DOI - 10.1111/bcpt.12280
Subject(s) - inosine , mapk/erk pathway , adenosine , cell growth , chemistry , adenosine deaminase , pi3k/akt/mtor pathway , kinase , cancer research , microbiology and biotechnology , signal transduction , biochemistry , biology
Malignant melanoma is the most deadly type of skin cancer. The lack of effective pharmacological approaches for this tumour can be related to the incomplete understanding of the pathophysiological mechanisms involved in melanoma cell proliferation. Adenosine has growth‐promoting and growth inhibitory effects on tumour cells. We aimed to investigate effects of adenosine and its metabolic product, inosine, on human C32 melanoma cells and the signalling pathways involved. The 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide ( MTT ) reduction and bromodeoxyuridine (BrdU) proliferation assays were used to evaluate adenosine, adenosine deaminase and inosine effects, in the absence or presence of adenosine receptor ( AR ), A 3 AR and P2Y 1 R antagonists and PLC , PKC , MEK 1/2 and PI 3K inhibitors. ERK 1/2 levels were determined using an ELISA kit. Adenosine and inosine levels were quantified using an enzyme‐coupled assay. Adenosine caused cell proliferation through AR activation. Adenosine deaminase increased inosine levels (nanomolar concentrations) on the extracellular space, in a time‐dependent manner, inducing proliferation through A 3 AR activation. Micromolar concentrations of inosine enhanced proliferation through A 3 AR activation, causing an increase in ERK 1/2 levels, and P2Y 1 R activation via ENT ‐dependent mechanisms. We propose the simultaneous activation of PLC ‐ PKC ‐ MEK 1/2‐ ERK 1/2 and PI 3K pathways as the main mechanism responsible for the proliferative effect elicited by inosine and its significant role in melanoma cancer progression.