Role of non-receptor and receptor tyrosine kinases (TKs) in the antitumor action of α-difluoromethylornithine (DFMO) in breast cancer cells

Abstract

We have shown that administration of a-difluoromethylornithine (DFMO), an irreversible inhibitor of ornithine decarboxylase (ODC), the first and rate-limiting enzyme in polyamine (PA) biosynthesis, reduces the invasive and metastatic properties of MDA-MB-435 breast cancer cells while activating multiple signal transduction pathways, including MAPK, Stat3, Stat1, and JNK. Since the activity of these signaling mechanisms is frequently regulated by upstream tyrosine kinases (TKs), we tested whether non-receptor and receptor TKs may be involved in the signaling and biological effects of DFMO in MDA-MB-435 cells. Treatment with DFMO (1 mM for 48 h) did not affect Src phosphorylation (Tyr 416). Administration of the Srcfamily members inhibitor PP-1 (1 lM), blocked Src phosphorylation in the absence and in the presence of DFMO, but did not block the signaling effects of DFMO (increased phosphorylation of Stat3, Stat1, ERK and JNK). PP-1 treatment, on the other hand, inhibited the invasiveness of MDA-MB-435 cells in matrigel and potentiated the antiinvasive effect of DFMO. Next, we focused on the role of receptor TK. Western analysis of cell lysates from MDA-MB-435 cells failed to show the presence of EGF-R and HER-2neu but demonstrated the expression of c-Met, the receptor for hepatocyte growth factor (HGF). Therefore, we tested the effect of DFMO on the HGF/c-Met pathway which is strongly implicated in the progression of human breast cancer. We found that DFMO treatment blocked HGFinduced c-Met phosphorylation in MDA-MB-435 cells, suggesting that its anti-invasion action may be mediated, at least in part, by blocking c-Met signaling. Next, we showed that 1 mM DFMO suppressed HGF induced invasiveness of MDA-MB-435 cells in matrigel. Combination administration of DFMO with suboptimal doses of PHA-665752, a specific c-Met inhibitor, reduced invasiveness to an even greater extent than the individual treatment. These findings indicate that Src-family members, while not involved in DFMO action, promote invasiveness of breast cancer cells and their inhibition may enhance the antitumor effect of PA depletion. Our data also point to inhibition of HGF/c-Met pathway as a possible novel approach to enhancing the antitumor action of DFMO.

Arginine Metabolism and Its Potential in Treatment of Colorectal Cancer

“…Increased ODC transcription and polyamine synthesis were detected in APC mutant mice. At the same time, the use of ODC inhibitors can significantly reduce the incidence of colon polyps and adenoma ( Battaglia et al, 2014 ), and can also be used for the chemoprevention of prostate adenocarcinoma and skin cancer ( Manni et al, 2004 ; Xu et al, 2008 ). There is evidence that limiting the meat consumption and inhibiting ODC activity can significantly reduce polyamine synthesis and incidence rate of colorectal cancer with ODC1 GA/AA genotype, compared to GG ( Zell et al, 2012 ).…”

Targeting Polyamines and Inflammation for Cancer Prevention

“…Besides prostate and colon cancer, polyamine metabolism (by use of polyamine synthesis inhibitors or polyamine catabolism activators) and inflammation (by use of NSAIDs) have been studied for many cancers, including skin, lung, bladder (Messing et al 2006; Herr 2007), cervical (Vlastos et al 2005), esophageal (Fong et al 2001), gastric (Takahashi et al 2000), pancreatic, and breast (Xu et al 2008). These agents have been used independent of each other and have shown varying results due to the lack of a consensus for the dose and the length of the study.…”

Expression-Based Diagnosis, Treatment Selection, and Drug Development for Breast Cancer

“…Dasatinib induced sensitivity to c-Met inhibition in TNBR cells in a pre-clinical study [ 76 ]. Src inhibitor PP-1 suppresses the invasiveness of breast cancer cells [ 77 ]. PP-1 and PP-2 inhibit breast cancer proliferation [ 78 ].…”