Functional characterization of lysine-specific demethylase 2 (LSD2/KDM1B) in breast cancer progression

Abstract

Flavin-dependent histone demethylases govern histone H3K4 methylation and act as important chromatin modulators that are extensively involved in regulation of DNA replication, gene transcription, DNA repair, and heterochromatin gene silencing. While the activities of lysine-specific demethylase 1 (LSD1/KDM1A) in facilitating breast cancer progression have been well characterized, the roles of its homolog LSD2 (KDM1B) in breast oncogenesis are relatively less understood. In this study, we showed that LSD2 protein level was significantly elevated in malignant breast cell lines compared with normal breast epithelial cell line. TCGA- Oncomine database showed that LSD2 expression is significantly higher in basal-like breast tumors compared to other breast cancer subtypes or normal breast tissue. Overexpression of LSD2 in MDA-MB-231 cells significantly altered the expression of key important epigenetic modifiers such as LSD1, HDAC1/2, and DNMT3B; promoted cellular proliferation; and augmented colony formation in soft agar; while attenuating motility and invasion. Conversely, siRNA-mediated depletion of endogenous LSD2 hindered growth of multiple breast cancer cell lines while shRNA-mediated LSD2 depletion augmented motility and invasion. Moreover, LSD2 overexpression in MDA-MB-231 cells facilitated mammosphere formation, enriched the subpopulation of CD49f+/EpCAM- and ALDHhigh, and induced the expression of pluripotent stem cell markers, NANOG and SOX2. In xenograft studies using immune-compromised mice, LSD2-overexpressing MDA-MB-231 cells displayed accelerated tumor growth but significantly fewer lung metastases than controls. Taken together, our findings provide novel insights into the critical and multifaceted roles of LSD2 in the regulation of breast cancer progression and cancer stem cell enrichment.

KDM1A microenvironment, its oncogenic potential, and therapeutic significance

“…In addition to KDM1A, its homolog KDM1B is highly expressed in breast cancer, particularly in invasive tumors [ 105 ]. The enhanced expression of KDM1B in MDA-MB-231 cells has been shown to alter the expression of key epigenetic regulators, i.e., KDM1A, HDAC1/2, and DNMT3B; stimulate cellular proliferation; and enhance colony formation in soft agar while decreasing motility and invasion [ 135 ]. Additionally, KDM1B overexpression in MDA-MB-231 cells led to increased tumor growth, facilitated mammosphere formation, and resulted in the induction of pluripotent stem cell markers, i.e., NANOG and SOX2.…”

“…Additionally, KDM1B overexpression in MDA-MB-231 cells led to increased tumor growth, facilitated mammosphere formation, and resulted in the induction of pluripotent stem cell markers, i.e., NANOG and SOX2. Thus, KDM1B also plays significant and multifaceted roles in breast cancer progression and the enrichment of cancer stem cells [ 135 ]. Knockout of KDM1B increases the expression of many key silenced genes that are significant in breast cancer development [ 105 ].…”

Lysine‑specific demethylase 2 contributes to the proliferation of small cell lung cancer by regulating the expression of TFPI‑2

“…Previous studies have shown that LSD2 regulates the expression of DNMT3B and TFPI-2 in breast cancer ( 14 , 15 ), and TFPI-2 also plays a tumor suppression role in a variety of tumors ( 16 , 17 ). We first detected the expression of TFPI-2 and DNMT3B in SCLC.…”

Targeting LSD2 in breast cancer

“…In our recent published research article, we reported that the level of LSD2 expression is significantly increased in breast cancer specimens in comparison to normal adjacent tissue, and LSD2 expression in invasive breast tumors is greater than that of non-invasive counterparts [ 5 ]. These findings indicate a tumor promoting role of LSD2 in breast cancer biology.…”

“…The precise mechanisms by which LSD2 regulates DNA methylation in breast cancer cells remain unknown. We found that LSD2 overexpression resulted in elevated expression of DNMT3B, which is a critical epigenetic modifier in promoting DNA methylation and gene silencing in cancer [ 5 ]. Based on these findings, we speculate that overexpression of LSD2 in breast cancer cells reduces levels of H3K4me2 that could subsequently generate a favorable chromatin environment for recruitment of DNMTs to specific genes to repress their transcriptional activity.…”