Abstract B18: Association between apoptotic response and KiSS1 modulation in NSCLC preclinical models treated with SAHA and cisplatin
Authors: Gatti Laura , De Cesare Michelandrea , Corno Cristina , Carenini Nives , Corna Elisabetta , Zaffaroni Nadia , Ciusani Emilio , Perego Paola 
Published: May 2016

Abstract
Non-Small-Cell Lung Cancer (NSCLC) is an aggressive disease with low responsiveness to chemotherapy. Platinum-based therapy is the standard of care for NSCLC with limited benefits due to the occurrence of resistance. Since histone deacetylases (HDAC) have been implicated in silencing of apoptotic pathways and failure to undergo apoptosis in response to antitumor agents may result in drug resistance, in the present study we examined the capability of SAHA (vorinostat), a pan-HDAC inhibitor to improve cisplatin-induced apoptosis in NSCLC models, focusing on the possible role of KiSS1, a well-known metastasis suppressor, which could be involved in apoptosis regulation.
Preclinical pharmacology approaches were employed including growth inhibition assays, western blot analyses, ELISA and antitumor activity tests in murine xenografts. The drug interaction was examined using the Bliss method.
We examined the effect of the combination of SAHA and cisplatin in the NSCLC H460 and A549 cell lines, including the cisplatin-resistant variants (H460/Pt, A549/Pt), which were found to exhibit enhanced invasive potential as compared to parental cells, besides reduced susceptibility to cisplatin-induced apoptosis. We observed that a synergistic interaction between SAHA and cisplatin occurred in cisplatin-sensitive H460 cells and in cisplatin-resistant H460/Pt cells, where it was less marked. The synergism was schedule-dependent because it was not observed following a simultaneous drug exposure, but when cells were pre-treated with SAHA for 24 h, a circumstance that we previously showed to up-regulate KiSS1 mRNA level. Under such a condition, increased levels of the pro-apoptotic protein Bax were detected by western blot analysis in cells exposed to the drug combination as compared to untreated and singly treated cells in both H460 and H460/Pt cells. Such a behaviour was associated with increased levels of apoptotic cells. Moreover, intracellular and extracellular levels of the KiSS1 protein tended to increase upon SAHA and combined treatment. In the A549 and A549/Pt cells an additive interaction was mainly observed. The efficacy of the combination was tested in vivo after subcutaneous inoculum of H460/Pt cells in immunodeficient mice. A significant tumor volume inhibition was found when mice bearing advanced tumors were treated with the combination of SAHA and cisplatin according to the best schedule identified in cellular studies.
Our findings indicate that the efficacy of the drug combination is schedule-dependent and may be influenced by the molecular background of the experimental models. The evidence of increased apoptosis in relation to KiSS1 up-modulation, together with previous findings of the involvement of KiSS1 in counteracting the invasive ability of NSCLC cells suggest a multi-tasking role for this factor.
Citation Format: Laura Gatti, Michelandrea De Cesare, Cristina Corno, Nives Carenini, Elisabetta Corna, Nadia Zaffaroni, Emilio Ciusani, Paola Perego. Association between apoptotic response and KiSS1 modulation in NSCLC preclinical models treated with SAHA and cisplatin. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B18.