CIGB 300 treatment in lung cancer cells: effect on NFkb inhibition and penetration in 3D spheroids

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

San Carlos de Bariloche

Congreso; Third Sudamerican Symposium in Signal Transduction and Molecular Medicine (SISTAM); 2015

Lung cancer is the leading cause of cancer deaths worldwide and despite the significant progress, current therapies are limited in efficacy. The CK2 Ser/Thr kinase has been historically linked to cancer. It affects cell proliferation, survival and apoptosis by activating diverse signaling pathways, including Wnt and NF-kB among the most relevant. CIGB-300 is an antitumor peptide with a novel mechanism of action, capable of binding to CK2 substrates thus preventing the enzyme activity. Previously, we have determined that CIGB-300 induced apoptosis through caspase-3 activation in different lung cancer cell lines. Moreover, this peptide also revert some characteristics associated with the malignant phenotype, such as migratory and invasive potential. We could also determine that CIGB-300 alters the ability of lung cancer cells to grow and form spheroids in three-dimensional cultures. Regarding the signaling pathways, involved in the above mentioned process, we found that CIGB-300 reverted b-catenin cytoplasmic accumulation, induced by the activation of Wnt pathway with a conditioned media containing the soluble wnt3a factor. Besides, CIGB-300 strongly inhibited RelA/NF-kB (p65) nuclear levels, even in the presence of a phorbol-ester activating stimulus. NF-kB activation is known to reduce chemotherapy efficiency in different cancer treatments, including lung cancer. Based on this evidence, we hypothesize that supplementing cisplatin with CIGB-300 would improve the treatment efficiency. Effectively, we could observe by Western blot that nuclear p65 levels where highly increased after treating human NCI-H125 cells during 45 minutes with the cisplatin IC50. Next, cells were treated with cisplatin plus CIGB-300. In this condition, NF-kB activation was completely abolished, detecting even in lower level of p65 than in the control situation. Therefore, the CIGB-300 effect on NF-kB signaling pathway overcomes cisplatin. As CIGB-300 inhibits 3D growth, we analyze whether this peptide was able to affect this compact spheroid structure that resembles an in vivo avascular tumor, a condition where the drug-entry is very difficult. A biotinylated version of CIGB-300 was used to treat NCI-H125 spheroids and it was tracked over time. By Immunohistochemistry we observed a fast and effective entrance of the peptide, detecting mark after 5 minutes of treatment and a complete spheroid penetration after 60 minutes. In conclusion, our results show that the treatment with CIGB-300 negatively modulates several characteristics associated to malignant progression by affecting different signaling pathways. Moreover, the promising results on NF-kB inhibition, even in combination with cisplatin, lead us to explore its effectiveness in chemoresistant settings.