A demethylation deficient isoform of the lysine demethylase KDM2A interacts with pericentromeric heterochromatin in an HP1a-dependent manner

DUX4-induced HSATII transcription causes KDM2A/B-PRC1 nuclear foci and impairs DNA damage response

Polycomb repressive complexes regulate developmental gene programs, promote DNA damage repair, and mediate pericentromeric satellite repeat repression. Expression of pericentromeric satellite repeats has been implicated in several cancers and diseases, including facioscapulohumeral dystrophy (FSHD). Here, we show that DUX4-mediated transcription of HSATII regions causes nuclear foci formation of KDM2A/B-PRC1 complexes, resulting in a global loss of PRC1-mediated monoubiquitination of histone H2A. Loss of PRC1-ubiquitin signaling severely impacts DNA damage response. Our data implicate DUX4-activation of HSATII and sequestration of KDM2A/B-PRC1 complexes as a mechanism of regulating epigenetic and DNA repair pathways.

Lysine Demethylase KDM2A Promotes Proteasomal Degradation of TCF/LEF Transcription Factors in a Neddylation-Dependent Manner

Canonical Wnt signaling is essential for a plethora of biological processes ranging from early embryogenesis to aging. Malfunctions of this crucial signaling pathway are associated with various developmental defects and diseases, including cancer. Although TCF/LEF transcription factors (TCF/LEFs) are known to be essential for this pathway, the regulation of their intracellular levels is not completely understood. Here, we show that the lysine demethylase KDM2A promotes the proteasomal destabilization of TCF/LEFs independently of its demethylase domain. We found that the KDM2A-mediated destabilization of TCF/LEFs is dependent on the KDM2A zinc finger CXXC domain. Furthermore, we identified the C-terminal region of TCF7L2 and the CXXC domain of KDM2A as the domains responsible for the interaction between the two proteins. Our study is also the first to show that endogenous TCF/LEF proteins undergo KDM2A-mediated proteasomal degradation in a neddylation-dependent manner. Here, we reveal a completely new mechanism that affects canonical Wnt signaling by regulating the levels of TCF/LEF transcription factors through their KDM2A-promoted proteasomal degradation.

A novel STAT3/ NFκB p50 axis regulates stromal-KDM2A to promote M2 macrophage-mediated chemoresistance in breast cancer

BACKGROUND

Lysine Demethylase 2A (KDM2A) plays a crucial role in cancer cell growth, differentiation, metastasis, and the maintenance of cancer stemness. Our previous study found that cancer-secreted IL-6 can upregulate the expression of KDM2A to promote further the transition of cells into cancer-associated fibroblasts (CAFs). However, the molecular mechanism by which breast cancer-secreted IL-6 regulates the expression of KDM2A remains unclear. Therefore, this study aimed to elucidate the underlying molecular mechanism of IL-6 in regulating KDM2A expression in CAFs and KDM2A-mediated paclitaxel resistance in breast cancer.

METHODS

The ectopic vector expression and biochemical inhibitor were used to analyze the KDM2A expression regulated by HS-578 T conditioned medium or IL-6 in mammary fibroblasts. Immunoprecipitation and chromatin immunoprecipitation assays were conducted to examine the interaction between STAT3 and NFκB p50. M2 macrophage polarization was assessed by analyzing M2 macrophage-specific markers using flow cytometry and RT-PCR. ESTIMATE algorithm was used to analyze the tumor microenvironment-dominant breast cancer samples from the TCGA database. The correlation between stromal KDM2A and CD163 + M2 macrophages was analyzed using the Pearson correlation coefficient. Cell viability was determined using trypan blue exclusion assay.

RESULTS

IL-6 regulates gene expression via activation and dimerization of STAT3 or collaboration of STAT3 and NFκB. However, STAT3, a downstream transcription factor of the IL-6 signaling pathway, was directly complexed with NFκB p50, not NFκB p65, to upregulate the expression of KDM2A in CAFs. Enrichment analysis of immune cells/stromal cells using TCGA-breast cancer RNA-seq data unveiled a positive correlation between stromal KDM2A and the abundance of M2 macrophages. CXCR2-associated chemokines secreted by KDM2A-expressing CAFs stimulated M2 macrophage polarization, which in turn secreted CCL2 to increase paclitaxel resistance in breast cancer cells by activating CCR2 signaling.

CONCLUSION

This study revealed the non-canonical molecular mechanism of IL-6 secreted by breast cancer upregulated KDM2A expression in CAFs via a novel STAT3/NFκB p50 axis, which STAT3 complexed with NFκB p50 in NFκB p50 binding motif of KDM2A promoter. KDM2A-expressing CAFs dominantly secreted the CXCR2-associated chemokines to promote M2 macrophage polarization and enhance paclitaxel resistance in breast cancer. These findings underscore the therapeutic potential of targeting the CXCR2 or CCR2 pathway as a novel strategy for paclitaxel-resistant breast cancer.

Expression pattern and regulatory effect of lysine-specific demethylase 2A gene in clear cell renal cell carcinoma

Background

Our study aimed to explore the expression and the biological role of lysine-specific demethylase 2A (KDM2A) in clear cell renal cell carcinoma (ccRCC).

Methods

In vitro, KDM2A expression was measured by qRT-PCR and western blot. A total of 50 patients with ccRCC were included, and KDM2A expression in ccRCC tissues was assessed by qRT-PCR and immunohistochemistry. The effects of KDM2A expression on cell biological behavior were examined by cell counting kit-8 assay, transwell assay and flow cytometry, respectively. The prognostic value of KDM2A in ccRCC was evaluated by Kaplan–Meier method.

Results

The KDM2A expression was significantly upregulated in ccRCC cell line (P < 0.05). Compared with para cancer tissues, ccRCC samples showed a higher KMD2A mRNA level and a larger proportion of high KDM2A expression (all P < 0.05). High KDM2A mRNA expression was more likely to occur in ccRCC tissues with tumor size > 7 cm (P = 0.005) and T3-T4 stage (P = 0.047). Knockdown of KDM2A significantly suppressed the proliferation and invasion, and promoted the apoptosis of ccRCC cells (all P < 0.05). Moreover, Kaplan–Meier survival analysis revealed that higher level of KDM2A expression in ccRCC patients was associated with lower survival rate (P = 0.004).

Conclusions

Our findings demonstrated a vital role of KDM2A in the pathogenesis of ccRCC, which provides a new perspective to understand the underlying molecular mechanisms in ccRCC.

Alternative isoforms of KDM2A and KDM2B lysine demethylases negatively regulate canonical Wnt signaling

A precisely balanced activity of canonical Wnt signaling is essential for a number of biological processes and its perturbation leads to developmental defects or diseases. Here, we demonstrate that alternative isoforms of the KDM2A and KDM2B lysine demethylases have the ability to negatively regulate canonical Wnt signaling. These KDM2A and KDM2B isoforms (KDM2A-SF and KDM2B-SF) lack the N-terminal demethylase domain, but they still have the ability to bind to CpG islands in promoters and to interact with their protein partners via their other functional domains. We have observed that KDM2A-SF and KDM2B-SF bind to the promoters of axin 2 and cyclin D1, two canonical Wnt signaling target genes, and repress their activity. Moreover, KDM2A-SF and KDM2B-SF are both able to strongly repress a Wnt-responsive luciferase reporter. The transcriptional repression mediated by KDM2A-SF and KDM2B-SF, but also by KDM2A-LF, is dependent on their DNA binding domain, while the N-terminal demethylase domain is dispensable for this process. Surprisingly, KDM2B-LF is unable to repress both the endogenous promoters and the luciferase reporter. Finally, we show that both KDM2A-SF and KDM2B-SF are able to interact with TCF7L1, one of the transcriptional mediators of canonical Wnt signaling. KDM2A-SF and KDM2B-SF are thus likely to negatively affect the transcription of canonical Wnt signaling target genes by binding to their promoters and by interacting with TCF7L1 and other co-repressors.

KDM2A/B lysine demethylases and their alternative isoforms in development and disease

Aberrant levels of histone modifications lead to chromatin malfunctioning and consequently to various developmental defects and human diseases. Therefore, the proteins bearing the ability to modify histones have been extensively studied and the molecular mechanisms of their action are now fairly well understood. However, little attention has been paid to naturally occurring alternative isoforms of chromatin modifying proteins and to their biological roles. In this review, we focus on mammalian KDM2A and KDM2B, the only two lysine demethylases whose genes have been described to produce also an alternative isoform lacking the N-terminal demethylase domain. These short KDM2A/B-SF isoforms arise through alternative promoter usage and seem to play important roles in development and disease. We hypothesise about the biological significance of these alternative isoforms, which might represent a more common evolutionarily conserved regulatory mechanism.