Atividade antitumoral in vitro de derivados 2-N,N´-dialquilamino-1,4-naftoquinonas sobre células de glioblastoma humano (GBM02)

Abstract

Glioblastoma multiforme (GBM) is a type of tumor originated in glial cells with high proliferation and invasiveness, which makes it the most malignant tumor of the Central Nervous System (CNS), associated with high morbidity and mortality index. Therapeutic interventions are based on tumor resection followed by radiotherapy and chemotherapy treatment, allowing an short average survival rate of only 15 months. Thus, it is necessary to search for new prototypes of drugs more effective for the treatment of GBM. Naphthoquinones (NQs) are included in the important class of natural products called quinones and are associated with several biological activities, including anticancer. Therefore, the present study evaluated the in vitro antitumor activity of 2-N, N'-dialkylamino-1,4-naphthoquinone derivatives (1a - 1n) against human glioblastoma cells (GBM02). Initially to evaluate the effects of the derivatives on the cell viability of GBM02 and blood mononuclear cells (monocytes and lymphocytes) the MTT colorimetric assay was used. Then, the derivatives selectivity was calculated by the ratio between cytotoxic concentrations against 50% of the monocytes and lymphocytes (CC50) and 50% inhibitory concentrations (IC50) against GBM02 cells. In sequence, the antimigratory effect on GBM02 cells after treatments was observed using the scratch assay. Morphological analyzes were performed by light microscopy and the mechanisms of tumor cell death (oxidative stress, cell cycle and apoptosis) were analyzed by flow cytometry. Results were expressed as the mean ± SEM and analyzed by one-way ANOVA followed by the Dunnett test, they were considered significant when *p <0.05, **p <0.01, and ***p <0.001 compared to control. All derivatives inhibited GBM02 cell viability except 1a, 1b, and 1c; the most effective ones were the derivatives 1d (69.2 ± 2.7%***), 1e (72.2 ± 1.2%***), 1f (72.5 ± 1.5%***), 1g (70.5 ± 0.2%***), 1h (67.6 ± 0.6%***), 1k (71.6 ± 0.1%***), and 1n (64.1 ± 1.4%***) and, among them, the most potent one was 1e (IC50 of 14.9 ± 4.6 μM). The derivatives 1a, 1l, and 1n were not toxic to monocytes and lymphocytes; and 1e (18.3 ± 11.1% *), 1f (31.6 ± 9.8% **), and 1g (18.9 ± 2.2%*) presented low cytotoxicity. The derivatives 1e (SI > 6.7), 1f (SI > 1.4), 1g (SI > 1.4), 1k (SI > 2.1), and 1n (SI > 2.4) were more selective for GBM02 cells than for monocytes and lymphocytes. Among those derivatives, only 1e (40.6%**) and 1n (72.4%***) inhibited GBM02 migration. Moreover, 1e and 1n provoked changes in the morphology of tumor cells, induced apoptosis in GBM02 cells and promoted cell cycle arrest in the S and G0/G1 phases, respectively. Only the derivative 1n (6.0%***) stimulated oxidative stress in GBM02 cells. The 2-N, N'-dialkylamino-1,4-naphthoquinone derivatives were more effective against GBM02 than the standard drug used in chemotherapeutic treatments, temozolomide (TMZ). Among all derivatives, 1e and 1n were the ones that presented the most satisfactory antitumor activity for inducing GBM02 apoptosis and causing less toxic effects to healthy human cells. In this way, these two derivatives have been shown to be effective antitumor agents and should be subjected to new experimental protocols in the antitumor drugs development chain, with the purpose of becoming future therapeutic options for this disease of poor prognosis and until then without cure.