HER Specific TKIs Exert Their Antineoplastic Effects on Breast Cancer Cell Lines through the Involvement of STAT5 and JNK

Abstract

BackgroundHER-targeted tyrosine kinase inhibitors (TKIs) have demonstrated pro-apoptotic and antiproliferative effects in vitro and in vivo. The exact pathways through which TKIs exert their antineoplastic effects are, however, still not completely understood.MethodsUsing Milliplex assays, we have investigated the effects of the three panHER-TKIs lapatinib, canertinib and afatinib on signal transduction cascade activation in SKBR3, T47D and Jurkat neoplastic cell lines. The growth-inhibitory effect of blockade of HER and of JNK and STAT5 signaling was measured by proliferation- and apoptosis-assays using formazan dye labeling of viable cells, Western blotting for cleaved PARP-1 and immunolabeling for active caspase 3, respectively.ResultsAll three HER-TKIs clearly inhibited proliferation and increased apoptosis in HER2 overexpressing SKBR3 cells, while their effect was less pronounced on HER2 moderately expressing T47D cells where they exerted only a weak antiproliferative and essentially no pro-apoptotic effect. Remarkably, phosphorylation/activation of JNK and STAT5A/B were inhibited by HER-TKIs only in the sensitive, but not in the resistant cells. In contrast, phosphorylation/activation of ERK/MAPK, STAT3, CREB, p70 S6 kinase, IkBa, and p38 were equally affected by HER-TKIs in both cell lines. Moreover, we demonstrated that direct pharmacological blockade of JNK and STAT5 abrogates cell growth in both HER-TKI-sensitive as well as -resistant breast cancer cells, respectively.ConclusionWe have shown that HER-TKIs exert a HER2 expression-dependent anti-cancer effect in breast cancer cell lines. This involves blockade of JNK and STAT5A/B signaling, which have been found to be required for in vitro growth of these cell lines.

Deciphering the Signaling Network Landscape of Breast Cancer Improves Drug Sensitivity Prediction

“…For example, cellular variability of p-STAT5 and p-STAT3 were predictive of lapatinib sensitivity and could therefore be used as a stratification marker. This is consistent with previous reports that inhibition of phosphorylation of JNK and STAT5 by lapatinib was observed only in sensitive cell lines (Gschwantler-Kaulich et al, 2016). PI3K mutational status is often not predictive of response to PI3K-targeted drugs.…”

“…Fig. 6A); median expression of the phosphorylated forms of STAT5 and STAT3 were previously reported to be predictive of lapatinib, canertinib, and afatinib sensitivity (Gschwantler-Kaulich et al, 2016). Interestingly, p-MK2 median expression correlated with sensitivity, and the p38·MK2 and ERK·MK2 edge fluxes strongly correlated with resistance and sensitivity, respectively.…”

HER2-induced metastasis is mediated by AKT/JNK/EMT signaling pathway in gastric cancer

“…In GC, the pivotal role of HER2 metastasis has been shown[6,29], but not much is known about the downstream effectors in this process. Although most studies have implicated AKT and ERK as promising therapeutic targets for HER2-positive tumors[27,28,30], JNK, especially in breast cancer, is now emerging as an important molecule in HER2 signaling pathways[11,12]. In the present study, we found positive associations between HER2, JNK and AKT in terms of GC metastasis.…”

“…Although a current study[12] reported that HER2 inhibition suppressed JNK activation in HER2-positive breast cancer cells, the relationship between these molecules could be different according to cellular context and cell type. To investigate the direct effect of HER2 on JNK activation, we performed in vitro experiments.…”

“…In general, JNK has been established as a key kinase in cancer cell apoptosis[10]. Recently, the role of JNK in HER2 signaling pathway has gained much attention, because JNK activation plays a critical role in the lapatinib-resistance in HER2-positve breast cancer cells[11,12]. However, regarding GC, the biological significance of JNK in relation to HER2 signaling has not been reported.…”