Anti-proliferative effects of halogenated boroxine - K2(B3O3F4OH) (HB) - have been confirmed in multiple cancer cell lines, including melanoma, but the exact mechanism of action is still unknown. This study aimed to determine its cytotoxic effects on human Caucasian melanoma (GR-M) cell growth in vitro as well as on the expression of cell death-related genes BCL-2, BECN1, DRAM1, and SQSTM1. GR-M and peripheral blood mononuclear (PBM) cells were treated with different HB concentrations and their growth inhibition and relative gene expression profiles were determined using the Alamar blue assay and real-time PCR. HB significantly inhibited cell growth of both GR-M and PBM cells but was even more effective in GR-M melanoma cells, as significant inhibition occurred at a lower HB concentration of 0.2 mg/mL. GR-M BCL-2 expression was significantly downregulated (P=0.001) at HB concentration of 0.4 mg/mL, which suggests that HB is a potent tumour growth inhibitor. At the same time, it upregulated BCL-2 expression in normal (PBM) cells, probably by activating protective mechanisms against induced cytotoxicity. In addition, all but the lowest HB concentrations significantly upregulated SQSTM1 (P=0.001) in GR-M cells. Upregulated BECN1 expression suggests early activation of autophagy at the lowest HB concentration in SQSTM1 cells and at all HB concentrations in PBM cells. Our findings clearly show HB-associated cell death and, along with previous cytotoxicity studies, reveal its promising anti-tumour potential.
Antiproliferativni učinci halogeniranoga boroksina – K2(B3O3F4OH) (HB) – potvrđeni su u više staničnih linija raka, uključujući melanom, ali točan mehanizam djelovanja još uvijek nije poznat. Cilj ovoga istraživanja bio je utvrditi njegove citotoksične učinke na rast stanica ljudskoga melanoma (GR-M) in vitro, kao i na ekspresiju gena BCL-2, BECN1, DRAM1 i SQSTM1, povezanih sa staničnom smrću. GR-M melanom i mononuklearne stanice periferne krvi (PBM) tretirane su različitim koncentracijama HB-a, a njihova inhibicija rasta i relativni profili ekspresije gena određeni su Alamar blue testom i real-time PCR-om. HB je značajno inhibirao rast GR-M melanoma i PBM stanica, no u GR-M melanomu učinci su registrirani pri nižim koncentracijama HB-a. Ekspresija BCL-2 gena u GR-M melanomu bila je značajno smanjena (P=0,001) pri koncentraciji od 0,4 mg/mL, što sugerira da je HB snažan inhibitor rasta tumora. Istodobno, pojačao je ekspresiju BCL-2 u normalnim PBM stanicama, vjerojatno aktiviranjem zaštitnih mehanizama protiv inducirane citotoksičnosti. Osim toga, sve osim najniže koncentracije HB-a značajno su povećale ekspresiju SQSTM1 (P=0,001) u GR-M melanomu. Povećana ekspresija BECN1 u najnižoj koncentraciji HB-a u GR-M stanicama i pri svim koncentracijama u PBM stanicama sugerira ranu aktivaciju autofagije. Naša otkrića jasno pokazuju indukciju stanične smrti povezane s HB-om i zajedno s prethodnim studijama citotoksičnosti otkrivaju njegov obećavajući antitumorski potencijal.
Keywords: BCL-2; BECN1, DRAM1; SQSTM1; anti-proliferative effect; antiproliferativni učinak; human Caucasian melanoma; ljudski kavkaski melanom; mononuklearne stanice periferne krvi; peripheral blood mononuclear cell.
© 2023 Nikolina Elez-Burnjaković et al., published by Sciendo.