These cancer stem-like cells also demonstrated self-renewal capacity in soft agar colony formation assay (48,49) (Fig1D, ?,3C)

These cancer stem-like cells also demonstrated self-renewal capacity in soft agar colony formation assay (48,49) (Fig1D, ?,3C).3C). to phosphorylate PKM2-Y105 in our tyrosine kinase screening. Introduction of the PKM2-Y105D phospho-mimetic mutant into MCF10A cells induced colony formation and the CD44hi/CD24neg cancer stem-like cell populace by increasing YAP protein nuclear localization. ErbB2, a strong inducer of PKM2-Y105 phosphorylation, boosted nuclear localization of YAP and enhanced the cancer stem-like cell Rabbit polyclonal to HMGCL populace. Treatment with the ErbB2 kinase inhibitor lapatinib decreased PKM2-Y105 phosphorylation and cancer stem-like cells, impeding PKM2 tumor-promoting function. Taken together, phosphorylation of PKM2-Y105 by activated kinases exerts oncogenic functions in part via activation of YAP downstream signaling to increase malignancy stem-like cell properties. gene encodes PKM1 and PKM2 isoforms by the mutually unique use of exons 9 and 10 (2). PKM2 has lower pyruvate kinase activity than PKM1, but PKM2 can be allosterically activated by its upstream metabolite fructose-1, 6-bisphosphate (FBP) (3,4). PKM1 is mainly expressed in the heart, muscle, and brain, while PKM2 is usually expressed in less differentiated, highly proliferating tissues, such as early fetal tissues, intestines, and especially most tumors (5). PKM2 has been shown to promote tumor growth by inhibiting apoptosis in tumor cells (6) or switching cancer metabolism to aerobic glycolysis and channeling nutrients into biosynthesis (7,8). PKM2 also has oncogenic functions that are impartial of its role in glycolysis. For example, upon EGFR activation, Erk1/2-dependent phosphorylation of PKM2 at Serine 37 (S37) promotes PKM2 translocation, which activates -catenin to promote U87 glioma tumor cell proliferation and tumorigenesis (9C11). However, the role of PKM2 in tumor progression is usually complex and controversial. PKM2 deletion in the mammary glands of a mammary epithelial cells. Therefore, part of the PKM2 oncogenic function is usually driven by its upstream oncogenic kinase activities. In addition GSK1324726A (I-BET726) to metabolic functions of PKM2 in promoting tumor growth (7,17), we revealed a novel mechanism that pY105-PKM2 induced cancer stem-like cell properties by promoting YAP nuclear translocation. Activation of YAP was shown to be critical for cell transformation (43) and correlated with cancer stem-like cell properties (35). Specifically, we found that pY105-PKM2 led to the destabilization of the Hippo kinase GSK1324726A (I-BET726) LATS1, thus reducing phosphorylation of YAP at S127 and preventing GSK1324726A (I-BET726) YAP cytoplasmic retention by 14-3-3 proteins (44). Consequently, S127-unphosphorylated YAP proteins translocated into the nucleus and activated downstream targets to promote malignant transformation. It will be fascinating to explore how PKM2 crosstalks to the Hippo pathway and regulates LATS1 protein stability in future studies. Malignancy stem cells (CSCs), or cancer-initiating cells, are defined as a subset of self-renewal cancer cells. Although the function of CSCs in tumorigenicity needs further ratification (45), substantial studies indicate that an important feature of CSCs is usually their tumor initiation capability, frequently indicated or measured by tumor formation in xenograft model (46,47). The CSCs in human breast cancers were first marked as CD44+/CD24?/low and 1000 of CD44+/CD24?/low CSCs, but not CD44+/CD24high breast malignancy cells, could induce tumors that can be serially transplanted in NOD/SCID mice (33). Another marker of CSCs in breast cancer is usually ALDH and 500 of ALDH+ CSCs, but not ALDH? breast malignancy cells, also formed xenograft tumors (34). In this study, we found that pY105-PKM2 significantly enhanced CD44hi/CD24neg and/or ALDH+ cancer stem-like cells in MCF10A and MDA.MB.231 cell lines (Figs. 3DCG). These cancer stem-like cells also exhibited self-renewal capacity in soft agar colony formation assay (48,49) (Fig1D, ?,3C).3C). Importantly, compared to PKM2-Y105F transduced H1299 lung cancer cells, PKM2 WT-transduced H1299 cells, in which PKM2-Y105 could be phosphorylated by activated oncogenic kinases and hence have more CSCs, induced significantly bigger xenograft tumors (17). These previous studies and our new findings support the notion that pY105-PKM2-induced cancer stem-like cells contribute, at least partly, to breast malignancy tumorigenicity. The intervention of cancer metabolic dysregulations has been considered as a promising.