ABSTRACT
Accumulating evidence has revealed that the methylation of lysines on nonhistones by histone lysine methyltransferases (HMTs) is crucial for regulating tumo-rigenesis and metastasis. However, whether the methy-lation of lysines on HMT complex components occurs and has functions in cancer progression is less well understood. WD repeat domain 5 (WDR5) is a core component of an HMT complex named mixed lineage leukemia (MLL)/Suppressor of Variegation, Enhancer of Zeste, and Trithorax 1 (SET1). In the present study, it was reported that lysines 207 and 325 (K207 and K325, respectively) of WDR5 were monomethylated by SETdomaincontaining protein methyltransferase 6. Disrupting the methylation of K207/K325 via a K207R/K325R doublesite mutation attenuated the WDR5 promotion of breast cancer cell proliferation and migration. Methylation of K207/K325 on WDR5 partially contributed to maintaining global histone trimethylation of lysine 4 on histone H3 levels, but did not affect MLL/SET1 complex assembly. These results further understanding of a potential posttranslational modification of WDR5, and imply that the methylation of lysines on HMT complex components is crucial for regulating human carcinogenesis.
Subject(s)
Breast Neoplasms/genetics , Histone-Lysine N-Methyltransferase/genetics , Protein Methyltransferases/genetics , Breast Neoplasms/metabolism , Breast Neoplasms/pathology , Cell Movement/genetics , Cell Proliferation/genetics , Female , Histone-Lysine N-Methyltransferase/metabolism , Humans , Intracellular Signaling Peptides and Proteins , Lysine/metabolism , MCF-7 Cells , Methylation , Myeloid-Lymphoid Leukemia Protein/genetics , Protein Methyltransferases/metabolismABSTRACT
EZH2 (the Enhancer of Zeste Homolog 2), as a key epigenetic regulator and EMT inducer, participates in a variety of cancer metastasis. EZH2 stability is regulated by several types of post-translational modifications (PTMs).The long non-coding RNAs (lncRNA) have been implicated to have critical roles in multiple carcinogenesis through a wide range of mechanisms, including modulating the stability of proteins. To date, whether the stability of EZH2 protein is regulated by lncRNAs remains unexplored. Here we report the discovery of ANCR modulating the stability of EZH2, and hence in the invasion and metastasis of breast cancer cells. We determined that ANCR potentiated the CDK1-EZH2 interaction, which then increased the intensity of phosphorylation at Thr-345 and Thr-487 sites of EZH2, facilitating EZH2 ubiquitination and hence its degradation. Moreover, we also uncover ANCR is an important player in breast cancer progression and metastasis mainly through decreasing EZH2 stability. More specifically, we initially found that ANCR level was lower in breast cancer tissues and breast cancer cell lines, in contrast to their normal counterparts. We then demonstrated that knockdown of ANCR induced an EMT program and promoted cell migration and invasion in MCF10A (epithelial cells), whereas ectopic expression of ANCR repressed breast cancer cells migration and invasion. Furthermore, we validated in a nude mouse model that overexpression of ANCR in highly malignant and invasive MDA-MB-231 breast cancer cells significantly reduced the ability of the cells to form tumors and prevented the lung metastasis in vivo. Based on these data, our findings define a new mechanism underlying modulation of EZH2 stability by linking ANCR interaction with EZH2 to promote its phosphorylation that facilitates EZH2 degradation and suppresses breast cancer progression.
Subject(s)
Breast Neoplasms/pathology , Enhancer of Zeste Homolog 2 Protein/metabolism , RNA, Long Noncoding/metabolism , Animals , Breast Neoplasms/metabolism , CDC2 Protein Kinase/antagonists & inhibitors , CDC2 Protein Kinase/genetics , CDC2 Protein Kinase/metabolism , Cadherins/metabolism , Cell Line, Tumor , Cell Movement , Cycloheximide/pharmacology , Enhancer of Zeste Homolog 2 Protein/antagonists & inhibitors , Enhancer of Zeste Homolog 2 Protein/genetics , Female , Gene Expression Regulation, Neoplastic/drug effects , Humans , Leupeptins/pharmacology , Lung Neoplasms/secondary , MCF-7 Cells , Mice , Mice, Inbred BALB C , Mice, Nude , Proteasome Endopeptidase Complex/chemistry , Proteasome Endopeptidase Complex/metabolism , Protein Binding , RNA, Long Noncoding/antagonists & inhibitors , RNA, Long Noncoding/genetics , Ubiquitin/metabolismABSTRACT
Epithelial to mesenchymal transition (EMT) plays an important role in many biological processes. The latest studies revealed that aggressive breast cancer, especially the triple-negative breast cancer (TNBC) subtype was frequently associated with apparent EMT, but the mechanisms are still unclear. NEDD9/HEF1/Cas-L is a member of the Cas protein family and was identified as a metastasis marker in multiple cancer types. In this study, we wished to discern the role of NEDD9 in breast cancer progression and to investigate the molecular mechanism by which NEDD9 regulates EMT and promotes invasion in triple-negative breast cancer. We showed that expression of NEDD9 was frequently upregulated in TNBC cell lines, and in aggressive breast tumors, especially in TNBC subtype. Knockdown of endogenous NEDD9 reduced the migration, invasion and proliferation of TNBC cells. Moreover, ectopic overexpression of NEDD9 in mammary epithelial cells led to a string of events including the trigger of EMT, activation of ERK signaling, increase of several EMT-inducing transcription factors and promotion of their interactions with the E-cadherin promoter. Data presented in this report contribute to the understanding of the mechanisms by which NEDD9 promotes EMT, and provide useful clues to the evaluation of the potential of NEDD9 as a responsive molecular target for TNBC chemotherapy.
