SESSION TITLE: Lung Cancer Posters I
SESSION TYPE: Original Investigation Poster
PRESENTED ON: Wednesday, October 29, 2014 at 01:30 PM - 02:30 PM
PURPOSE: Lung cancer is the leading cause of cancer death in both men and women; non-small cell lung cancer (NSCLC) has an overall 5-year survival rate of 15%. Loss-of-function mutations or silencing of Pten and Lkb1 and aberrant Stat3 activation are observed frequently in NSCLC. Our objectives were to determine if Stat3 is activated in the lungs of a Pten and Lkb1 tissue specific knockout mouse, as well as in a panel of human NSCLC cell lines, and to determine the effect of two small-molecule Stat3 inhibitors, C188-9 and piperlongumine (PL), on activated Stat3 levels and growth of NSCLC cell lines in vitro.
METHODS: C188-9 was developed using computer-based docking of compounds into the phosphotyrosyl-peptide binding pocket of Stat3, while PL was identified in a drug repurposing screen. Pten knockout (KO) and Lkb1 KO mice were generated by crossing mice containing improved Cre recombinase (iCre) downstream of the Clara cell secretory protein (CCSPiCre) with mice containing a floxed Pten gene or a floxed Lkb1 gene; the lung-specific Pten/Lkb1 double KO (CCSPicre Ptenf/f Lkb1f/f) mouse was generated by crossing the Pten KO mouse with Lkb1 KO mouse. Eight NSCLC human cell lines were obtained from the ATTC and a normal lung cell line, HBEC3-KT, was obtained from John Minna (UT-SW).
RESULTS: Adenocarcinoma of the lung spontaneously developed in 100% of CCSPicre Ptenf/f Lkb1f/f mice. The level of pStat3 was increased 2-fold in lung and tumor tissue from these animals at 3 months (p<0.01) and was increased 2- to 6-fold in 7 of 8 NSCLC cell lines. We established a stably transfected cell line (A549/shSTAT3) in which STAT3 mRNA and protein were down regulated. Anchorage- dependent and independent cell viability was reduced by 50% in A549/shSTAT3 in which Stat3 was decreased by 60%. C188-9 and PL reduced pStat3 levels in all 4 tested NSCLC cell lines by 50% and reduced anchorage-dependent and independent cell viability of multiple NSCLC cell lines with IC50 values ranging from 3.06 -52.44mM and 0.86-6.27mM, respectively. C 188-9 stopped progression from G0/G1 to S phase in A549 cells after 24hr incubation whereas PL increased the rate of apoptosis.
CONCLUSIONS: Stat3 is activated in normal-appearing lung and lung tumors of CCSPicre Ptenf/f Lkb1f/f mice and in most human NSCLC cell lines. C188-9 and PL are potent inhibitors of constitutive Stat3 activation and growth of NSCLC cell lines in vitro.
CLINICAL IMPLICATIONS: Thus, Stat3 targeting may be a useful strategy for prevention and treatment of NSCLC.
DISCLOSURE: The following authors have nothing to disclose: Katherine Lewis, Uddalak Bharadwaj, T. Kris Eckols, Mikhail Kolosov, Moses M. Kasembeli, Sung-Nam Cho, Jian Liu, Francesco J. DeMayo, David J. Tweardy
The presenter will be discussing two small molecule inhibitors not yet approved for the treatment of non-small cell lung cancer.