Abstract 2626: Novel naphtoquinone PIC21 targets PI3K in triple negative breast cancer cell line
Authors: Daltoe Renata D. , Madeira Klesia P. , Cerri Murilo F. , Filho João F. Allochio , Delarmelina Maicon , Porto Marcella L. , Meirelles Silvana S. , Meirelles Silvana S. , Silva Ian V. , Greco Sandro J. , Rangel Leticia B A 
Published: May 2015

Background: Triple negative breast cancer (TNBC) is a heterogeneous subgroup (ER-, PR-, and HER2-) of aggressive breast cancer, which poor prognosis is partially due to chemoresistance to available drugs. We have synthesized and screened 43 novel naphtoquinone-derived drugs (patent-protected), rationally designed to act through multiple pathways to avoid tumor chemoresistance, in MDA-MB231 by cellular metabolic viability and IC50 calculation. Of these, the most promising drugs PIC20 and PIC21 showed significantly higher AE than cisplatin, doxorubicin and paclitaxel in the lineage.

Methods: Based on the crystalline structure of protein deposited on Protein Data Bank ( 1E7U, PI3K), and PIC20 and PIC21 tridimensional structures, computational molecular dock studies were conducted to investigate the molecules PIC20 e PIC21 tridimensional conformation and bounding energy to PI3K (Autodock Vina software). In vitro PI3K inhibition by PIC21 in MDA-MB231 was assessed using the Flowcellect PI3K/Mapk Dual Pathway Activation and Cancer Marker Detection. For PI3K/Akt and MAPK signaling pathways, cells were pre treated with PIC21 (0,1mM, 2h) or Wortmannin (Wort) (0,1μM, 30 min). Cells were then treated with insulin (0,6μM, 5 min) for stimulation of PI3K/Akt and MAPK pathways and incubated with Anti-phospho-Akt1/PKBα Alexa Fluor® 488 Conjugated Antibody and Anti-phospho-Erk1/2- R- Phycoerythrin conjugated antibody. A FACSCanto II cytometer was used for the flow cytometric analysis. FSC and SSC were used to establish size gates and exclude cellular debris from the analysis. In each measurement, a minimum of 30000 events were analyzed. Data were acquired and analyzed using BD FACSDiva and DeNovo FCS software.

Findings: PIC21 targeting of PI3K was confirmed by docking studies, which data demonstrated that the interaction energy (E) for PI3K and PIC21, and PI3K inhibitors, LY294002 and Wort, was: PIC20 (E=-8.9), PIC21(E=-8.2), LY294002 (E=-9.5), Wort (E=-8.8). Cell treatment with PIC21 and Wort decreased the pAkt+ cell population (control=23.02%, PIC21 treated=6.63%, Wort treated=4.20%), whereas the pERK+ cell population increased (control=0,58%, PIC21 treated=6,41%, Wort treated=10,14%. This is due to the pathways crosstalk, by which pAkt inhibits the MAPK/ERK pathway.

Conclusions: Our data strongly points to PIC21 as a novel PI3K inhibitor. A high prevalence of PI3K mutation, leading to its constitutive activation, has been described in TNBC, favoring tumor cells growth, proliferation, metabolism, and survival. Therefore, PIC21 opens a new avenue to overcome TNBC dramatic epidemiological scenario, bringing hope to improve patients overall outcome and quality of life.

Citation Format: Renata D. Daltoe, Klesia P. Madeira, Murilo F. Cerri, João F. Allochio Filho, Maicon Delarmelina, Marcella L. Porto, Silvana S. Meirelles, Silvana S. Meirelles, Ian V. Silva, Sandro J. Greco, Leticia B A Rangel. Novel naphtoquinone PIC21 targets PI3K in triple negative breast cancer cell line. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2626. doi:10.1158/1538-7445.AM2014-2626