The inhibition of protein kinase CK2 activity by the CIGB-300 synthetic peptide impairs the three-dimensional cell growth, Wnt and nuclear factor kB signaling pathways in lung cancer cells

STÉFANO M. CIRIGLIANO; MARIA I. DIAZ BESSONE; CAROLINA FLUMIAN; DAMIAN E. BERARDI; SILVIO PEREA; ELISA D. BAL DE KIER JOFFE; HERNÁN FARINA; LAURA B. TODARO; ALEJANDRO J. URTREGER

San Diego

Congreso; 105th Annual Meeting of the American Associaton for Cancer Research; 2014

American Associaton for Cancer Research (AACR)

CK2 is a serine/threonine kinase involved in cell growth, survival and apoptosis. The CIGB-300 is a synthetic peptide capable of binding to CK2 substrates thus preventing the enzyme activity. Previously we have determined that CIGB-300 presented an inhibitory concentration 50 dose (IC50) of 119±2.4 uM in NCI-H125 human lung cancer cells. Throughout an Annexin V-FITC assay we could determine that CIGB-300 is a potent apoptosis inductor since the treatment with this drug for 60 minutes induced apoptosis at a level comparable with that observed with etoposide (10 uM). Concomitantly with cell death induction, we could observe caspase-3 activation and the decreased expression of c-myc and cyclin D1 and D2. In this work we analyzed whether CIGB-300 is able to alter the ability of cells to grow in 3D and to modulate signaling pathways involved in tumor progression. First, we developed stable spheroids of NCI-H125 cells, which were able to grow in culture for at least 14 days. After 5 days of treatment, CIGB-300 induced a significant growth inhibition (median volume: 4.07x107±0.70x107 um3 in control spheroids vs 2.13x107±0.35x107 um3 in spheroids treated with the IC50 dose p=0.05). From the sixth day of treatment the size of the spheroids was dramatically reduced, returning to the initial volume on day eight. To analyze the effect of CIGB-300 on canonical Wnt signaling, this pathway was initially activated by incubating NCI-H125 cells with a conditioned media containing Wnt3a factor. This incubation led to a significant increase in the levels of cytoplasmic b-catenin. By Western blot we could observe that treatment with CIGB-300 blocked this increase, suggesting its role in the modulation of the Wnt pathway. In order to analyze the nuclear factor kB (NFkB) dependent pathway, this transcription factor was activated by a phorbol ester treatment (PMA, 15 nM). Short treatment (15 min) with CIGB-300 induced an important reduction in NF-kB nuclear levels. However, this inhibition was reverted 24 h later as determined by Western blot and reporter gene expression assays. Our results indicate that the treatment with CIGB-300 induces a significant anti-proliferative response in a three-dimensional model, which resembles in vivo tumor growth conditions, also affecting key signaling pathways involved in tumor progression. Altogether, our data suggest that this peptide may become a new strategy for the treatment of lung cancer malignancies.