Therapeutic potential of targeting LSD1/ KDM1A in cancers

Role of Histone Modifications in Kidney Fibrosis

Chronic kidney disease (CKD) is characterized by persistent kidney dysfunction, ultimately resulting in end-stage renal disease (ESRD). Renal fibrosis is a crucial pathological feature of CKD and ESRD. However, there is no effective treatment for this condition. Despite the complex molecular mechanisms involved in renal fibrosis, increasing evidence highlights the crucial role of histone modification in its regulation. The reversibility of histone modifications offers promising avenues for therapeutic strategies to block or reverse renal fibrosis. Therefore, a comprehensive understanding of the regulatory implications of histone modifications in fibrosis may provide novel insights into more effective and safer therapeutic approaches. This review highlights the regulatory mechanisms and recent advances in histone modifications in renal fibrosis, particularly histone methylation and histone acetylation. The aim is to explore the potential of histone modifications as targets for treating renal fibrosis.

Combination Therapy and Dual-Target Inhibitors Based on LSD1: New Emerging Tools in Cancer Therapy

Lysine specific demethylase 1 (LSD1), a transcriptional modulator that represses or activates target gene expression, is overexpressed in many cancer and causes imbalance in the expression of normal gene networks. Over two decades, numerous LSD1 inhibitors have been reported, especially some of which have entered clinical trials, including eight irreversible inhibitors (TCP, ORY-1001, GSK-2879552, INCB059872, IMG-7289, ORY-2001, TAK-418, and LH-1802) and two reversible inhibitors (CC-90011 and SP-2577). Most clinical LSD1 inhibitors demonstrated enhanced efficacy in combination with other agents. LSD1 multitarget inhibitors have also been reported, exampled by clinical dual LSD1/histone deacetylases (HDACs) inhibitors 4SC-202 and JBI-802. Herein, we present a comprehensive overview of the combination of LSD1 inhibitors with various antitumor agents, as well as LSD1 multitarget inhibitors. Additionally, the challenges and future research directionsare also discussed, and we hope this review will provide new insight into the development of LSD1-targeted anticancer agents.

A novel fusion technology utilizing complex network and sequence information for FAD-binding site identification

Flavin adenine dinucleotide (FAD) binding sites play an increasingly important role as useful targets for inhibiting bacterial infections. To reveal protein topological structural information as a reasonable complement for the identification FAD-binding sites, we designed a novel fusion technology according to sequence and complex network. The specially designed feature vectors were combined and fed into CatBoost for model construction. Moreover, due to the minority class (positive samples) is more significant for biological researches, a random under-sampling technique was applied to solve the imbalance. Compared with the previous methods, our methods achieved the best results for two independent test datasets. Especially, the MCC obtained by FADsite and FADsite_seq were 14.37 %-53.37 % and 21.81 %-60.81 % higher than the results of existing methods on Test6; and they showed improvements ranging from 6.03 % to 21.96 % and 19.77 %-35.70 % on Test4. Meanwhile, statistical tests show that our methods significantly differ from the state-of-the-art methods and the cross-entropy loss shows that our methods have high certainty. The excellent results demonstrated the effectiveness of using sequence and complex network information in identifying FAD-binding sites. It may be complementary to other biological studies. The data and resource codes are available at https://github.com/Kangxiaoneuq/FADsite.

Repression of LSD1 potentiates homologous recombination-proficient ovarian cancer to PARP inhibitors through down-regulation of BRCA1/2 and RAD51

Poly (ADP-ribose) polymerase inhibitors (PARPi) are selectively active in ovarian cancer (OC) with homologous recombination (HR) deficiency (HRD) caused by mutations in BRCA1/2 and other DNA repair pathway members. We sought molecular targeted therapy that induce HRD in HR-proficient cells to induce synthetic lethality with PARPi and extend the utility of PARPi. Here, we demonstrate that lysine-specific demethylase 1 (LSD1) is an important regulator for OC. Importantly, genetic depletion or pharmacological inhibition of LSD1 induces HRD and sensitizes HR-proficient OC cells to PARPi in vitro and in multiple in vivo models. Mechanistically, LSD1 inhibition directly impairs transcription of BRCA1/2 and RAD51, three genes essential for HR, dependently of its canonical demethylase function. Collectively, our work indicates combination with LSD1 inhibitor could greatly expand the utility of PARPi to patients with HR-proficient tumor, warranting assessment in human clinical trials.

Novel acridine-based LSD1 inhibitors enhance immune response in gastric cancer

Recently, histone lysine specific demethylase 1 (LSD1) has become an emerging and promising target for cancer immunotherapy. Herein, based on our previously reported LSD1 inhibitor DXJ-1 (also called 6x), a series of novel acridine-based LSD1 inhibitors were identified via structure optimizations. Among them, compound 5ac demonstrated significantly enhanced inhibitory activity against LSD1 with an IC50 value of 13 nM, about 4.6-fold more potent than DXJ-1 (IC50 = 73 nM). Molecular docking studies revealed that compound 5ac could dock well into the active site of LSD1. Further mechanism studies showed that compound 5ac inhibited the stemness and migration of gastric cancer cells, and reduced the expression of PD-L1 in BGC-823 and MFC cells. More importantly, BGC-823 cells were more sensitive to T cell killing when treated with compound 5ac. Besides, the tumor growth was also suppressed by compound 5ac in mice. Together, 5ac could serve as a promising candidate to enhance immune response in gastric cancer.

Lysin (K)-specific demethylase 1 inhibition enhances proteasome inhibitor response and overcomes drug resistance in multiple myeloma

BACKGROUND

Multiple myeloma (MM) is an incurable plasma cell malignancy, accounting for approximately 1% of all cancers. Despite recent advances in the treatment of MM, due to the introduction of proteasome inhibitors (PIs) such as bortezomib (BTZ) and carfilzomib (CFZ), relapses and disease progression remain common. Therefore, a major challenge is the development of novel therapeutic approaches to overcome drug resistance, improve patient outcomes, and broaden PIs applicability to other pathologies.

METHODS

We performed genetic and drug screens to identify new synthetic lethal partners to PIs, and validated candidates in PI-sensitive and -resistant MM cells. We also tested best synthetic lethal interactions in other B-cell malignancies, such as mantle cell, Burkitt's and diffuse large B-cell lymphomas. We evaluated the toxicity of combination treatments in normal peripheral blood mononuclear cells (PBMCs) and bone marrow stromal cells (BMSCs). We confirmed the combo treatment' synergistic effects ex vivo in primary CD138+ cells from MM patients, and in different MM xenograft models. We exploited RNA-sequencing and Reverse-Phase Protein Arrays (RPPA) to investigate the molecular mechanisms of the synergy.

RESULTS

We identified lysine (K)-specific demethylase 1 (LSD1) as a top candidate whose inhibition can synergize with CFZ treatment. LSD1 silencing enhanced CFZ sensitivity in both PI-resistant and -sensitive MM cells, resulting in increased tumor cell death. Several LSD1 inhibitors (SP2509, SP2577, and CC-90011) triggered synergistic cytotoxicity in combination with different PIs in MM and other B-cell neoplasms. CFZ/SP2509 treatment exhibited a favorable cytotoxicity profile toward PBMCs and BMSCs. We confirmed the clinical potential of LSD1-proteasome inhibition in primary CD138+ cells of MM patients, and in MM xenograft models, leading to the inhibition of tumor progression. DNA damage response (DDR) and proliferation machinery were the most affected pathways by CFZ/SP2509 combo treatment, responsible for the anti-tumoral effects.

CONCLUSIONS

The present study preclinically demonstrated that LSD1 inhibition could provide a valuable strategy to enhance PI sensitivity and overcome drug resistance in MM patients and that this combination might be exploited for the treatment of other B-cell malignancies, thus extending the therapeutic impact of the project.

Lysine-specific demethylase 1 as a therapeutic cancer target: observations from preclinical study

INTRODUCTION

Lysine-specific histone demethylase 1A (KDM1A/LSD1) has emerged as an important therapeutic target in various cancer types. LSD1 regulates a wide range of biological processes that influence cancer development, progression, metastasis, and therapy resistance. However, recent studies have revealed novel aspects of LSD1 biology, shedding light on its involvement in immunogenicity, antitumor immunity, and DNA damage response. These emerging findings have the potential to be leveraged in the design of effective LSD1-targeted therapies.

AREAS COVERED

This paper discusses the latest developments in the field of LSD1 biology, focusing on its role in regulating immunogenicity, antitumor immunity, and DNA damage response mechanisms. The newfound understanding of these mechanisms has opened possibilities for the development of novel LSD1-targeted therapies for cancer treatment. Additionally, the paper provides an overview of LSD1 inhibitor-based combination therapies for the treatment of cancer.

EXPERT OPINION

Exploiting LSD1 role in antitumor immunity and DNA damage response provides cues to not only understand the LSD1-resistant mechanisms but also rationally design new combination therapies that are more efficient and less toxic than monotherapy. The exploration of LSD1 biology and the development of LSD1-targeted therapies hold great promise for the future of cancer treatment.

Histone demethylases in the regulation of immunity and inflammation

Pathogens or danger signals trigger the immune response. Moderate immune response activation removes pathogens and avoids excessive inflammation and tissue damage. Histone demethylases (KDMs) regulate gene expression and play essential roles in numerous physiological processes by removing methyl groups from lysine residues on target proteins. Abnormal expression of KDMs is closely associated with the pathogenesis of various inflammatory diseases such as liver fibrosis, lung injury, and autoimmune diseases. Despite becoming exciting targets for diagnosing and treating these diseases, the role of these enzymes in the regulation of immune and inflammatory response is still unclear. Here, we review the underlying mechanisms through which KDMs regulate immune-related pathways and inflammatory responses. In addition, we also discuss the future applications of KDMs inhibitors in immune and inflammatory diseases.

Pharmacological inhibition of LSD1 suppresses growth of hepatocellular carcinoma by inducing GADD45B

Lysine-specific histone demethylase 1 (LSD1) is an attractive target for malignancies therapy. Nevertheless, its role in hepatocellular carcinoma (HCC) progression and the potential of its inhibitor in HCC therapy remains unclear. Here, we show that LSD1 overexpression in human HCC tissues is associated with HCC progression and poor patient survival. ZY0511, a highly selective and potent inhibitor of LSD1, suppressed human HCC cell proliferation in vitro and tumor growth in cell-derived and patient-derived HCC xenograft models in vivo. Mechanistically, ZY0511 induced mRNA expression of growth arrest and DNA damage-inducible gene 45beta (GADD45B) by inducing histone H3 at lysine 4 (H3K4) methylation at the promoter of GADD45B, a novel target gene of LSD1. In human HCC tissues, LSD1 level was correlated with a decreased level of GADD45B, which was associated with HCC progression and predicted poor patient survival. Moreover, co-administration of ZY0511 and DTP3, which specifically enhanced the pro-apoptotic effect of GADD45B, effectively inhibited HCC cell proliferation both in vitro and in vivo. Collectively, our study revealed the potential value of LSD1 as a promising target of HCC therapy. ZY0511 is a promising candidate for HCC therapy through upregulating GADD45B, thereby providing a novel combinatorial strategy for treating HCC.

Metabolic Interventions in Tumor Immunity: Focus on Dual Pathway Inhibitors

The metabolism of tumors and immune cells in the tumor microenvironment (TME) can affect the fate of cancer and immune responses. Metabolic reprogramming can occur following the activation of metabolic-related signaling pathways, such as phosphoinositide 3-kinases (PI3Ks) and the mammalian target of rapamycin (mTOR). Moreover, various tumor-derived immunosuppressive metabolites following metabolic reprogramming also affect antitumor immune responses. Evidence shows that intervention in the metabolic pathways of tumors or immune cells can be an attractive and novel treatment option for cancer. For instance, administrating inhibitors of various signaling pathways, such as phosphoinositide 3-kinases (PI3Ks), can improve T cell-mediated antitumor immune responses. However, dual pathway inhibitors can significantly suppress tumor growth more than they inhibit each pathway separately. This review discusses the latest metabolic interventions by dual pathway inhibitors as well as the advantages and disadvantages of this therapeutic approach.

Discovery of novel N-benzylarylamide-dithiocarbamate based derivatives as dual inhibitors of tubulin polymerization and LSD1 that inhibit gastric cancers

In this work, N-benzylarylamide-dithiocarbamate based derivatives were designed, synthesized, and their biological activities as anticancer agents were explored. Some of the 33 target compounds displayed significant antiproliferative activities with IC₅₀ values at the double-digit nanomolar level. The representative compound I-25 (also named MY-943) not only showed the most effective inhibitory effects on three selected cancer cells MGC-803 (IC₅₀ = 0.017 μM), HCT-116 (IC₅₀ = 0.044 μM) and KYSE450 (IC₅₀ = 0.030 μM), but also exhibited low nanomolar IC₅₀ values from 0.019 to 0.253 μM against the other 11 cancer cells. Compound I-25 (MY-943) effectively inhibited tubulin polymerization and suppressed LSD1 at the enzymatic levels. Compound I-25 (MY-943) could act on the colchicine binding site of β-tubulin, thus disrupting the construction of cell microtubule network and affecting the mitosis. In addition, compound I-25 (MY-943) could dose-dependently induce the accumulation of H3K4me1/2 (MGC-803 and SGC-7091 cells) and H3K9me2 (SGC-7091 cells). Compound I-25 (MY-943) could induce G2/M phase arrest and cell apoptosis, and suppress migration in MGC-803 and SGC-7901 cells. In addition, compound I-25 (MY-943) significantly modulated the expression of apoptosis- and cycle-related proteins. Furthermore, the binding modes of compound I-25 (MY-943) with tubulin and LSD1 were explored by molecular docking. The results of in vivo anti-gastric cancer assays using in situ tumor models showed that compound I-25 (MY-943) effectively reduced the weight and volume of gastric cancer in vivo without obvious toxicity. All these findings suggested that the N-benzylarylamide-dithiocarbamate based derivative I-25 (MY-943) was an effective dual inhibitor of tubulin polymerization and LSD1 that inhibited gastric cancers.

Discovery of acridine-based LSD1 inhibitors as immune activators targeting LSD1 in gastric cancer

LSD1 is overexpressed in various cancers and promotes tumor cell proliferation, tumor expansion, and suppresses immune cells infiltration and is closely associated with immune checkpoint inhibitors therapy. Therefore, the inhibition of LSD1 has been recognized as a promising strategy for cancer therapy. In this study, we screened an in-house small-molecule library targeting LSD1, an FDA-approved drug amsacrine for acute leukemia and malignant lymphomas was found to exhibit moderate anti-LSD1 inhibitory activity (IC₅₀ = 0.88 μM). Through further medicinal chemistry efforts, the most active compound 6x increased anti-LSD1 activity significantly (IC₅₀ = 0.073 μM). Further mechanistic studies demonstrated that compound 6x inhibited the stemness and migration of gastric cancer cell, and decreased the expression of PD-L1 (programmed cell death-ligand 1) in BGC-823 and MFC cells. More importantly, BGC-823 cells are more susceptible to T-cell killing when treated with compound 6x. Moreover, tumor growth was also suppressed by compound 6x in mice. Altogether, our findings demonstrated that acridine-based novel LSD1 inhibitor 6x may be a lead compound for the development of activating T cell immune response in gastric cancer cells.

Discovery of novel tranylcypromine-based derivatives as LSD1 inhibitors for gastric cancer treatment

As an important epigenetic regulator, histone lysine specific demethylase 1 (LSD1) has become an attractive target for the discovery of anticancer agents. In this work, a series of tranylcypromine-based derivatives were designed and synthesized. Among them, compound 12u exhibited the most potent inhibitory potency on LSD1 (IC₅₀ = 25.3 nM), and also displayed good antiproliferative effects on MGC-803, KYSE450 and HCT-116 cells with IC₅₀ values of 14.3, 22.8 and 16.3 μM, respectively. Further studies revealed that compound 12u could directly act on LSD1 and inhibit LSD1 in MGC-803 cells, thereby significantly increasing the expression levels of mono-/bi-methylation of H3K4 and H3K9. In addition, compound 12u could induce apoptosis and differentiation, inhibit migration and cell stemness in MGC-803 cells. All these findings suggested that compound 12u was an active tranylcypromine-based derivative as a LSD1 inhibitor that inhibited gastric cancer.

Ruta angustifolia Pers. (Narrow-Leaved Fringed Rue): Pharmacological Properties and Phytochemical Profile

The genus Ruta in the family Rutaceae includes about 40 species, such as the well-known plants R. graveolens L. (common rue) or R. chalepensis L. (fringed rue), but also much lesser-known species such as R. angustifolia Pers. (narrow-leaved fringed rue). This rue specie, originating from the Mediterranean region, is well-distributed in Southeast Asia, notably in the Indo-Chinese peninsula and other territories. In some countries, such as Malaysia, the plant is used to treat liver diseases and cancer. Extracts of R. angustifolia display antifungal, antiviral and antiparasitic effects. Diverse bioactive natural products have been isolated from the aerial parts of the plant, notably quinoline alkaloids and furocoumarins, which present noticeable anti-inflammatory, antioxidant and/or antiproliferative properties. The present review discusses the main pharmacological properties of the plant and its phytoconstituents, with a focus on the anticancer activities evidenced with diverse alkaloids and terpenoids isolated from the aerial parts of the plant. Quinoline alkaloids such as graveoline, kokusaginine, and arborinine have been characterized and their mode of action defined. Arborinine stands as a remarkable inhibitor of histone demethylase LSD1, endowed with promising anticancer activities. Other anticancer compounds, such as the furocoumarins chalepin and rutamarin, have revealed antitumor effects. Their mechanism of action is discussed together with that of other bioactive natural products, including angustifolin and moskachans. Altogether, R. angustifolia Pers. presents a rich phytochemical profile, fully consistent with the traditional use of the plant to treat cancer. This rue species, somewhat neglected, warrant further investigations as a medicinal plant and a source of inspiration for drug discovery and design.

Lysine-Specific Demethylase 1 (LSD1)-Mediated Epigenetic Modification of Immunogenicity and Immunomodulatory Effects in Breast Cancers

Tumor evolution to evade immune surveillance is a hallmark of carcinogenesis, and the modulation of tumor immunogenicity has been a challenge to present therapeutic responses in immunotherapies alone for numerous cancers. By altering the cell phenotype and reshaping the tumor microenvironment, epigenetic modifications enable tumor cells to overcome immune surveillance as a mechanism of cancer progression and immunotherapy resistance. Demethylase enzymatic activity of lysine-specific demethylase 1 (LSD1), a histone demethylase first identified in 2004, plays a pivotal role in the vast cellular processes of cancer. While FDA-approved indications for epigenetic therapies are limited to hematological malignancies, it is imperative to understand how epigenetic machinery can be targeted to prime immunotherapy responses in breast cancers. In this review, we discuss the potential roles of epigenetics and demethylating agent LSD1 as a potent new cancer management strategy to combat the current challenges of breast cancers, which have presented modest efficacy to immune checkpoint inhibitors till date. Additionally, we describe the combined use of LSD1-specific inhibitors and immune checkpoint inhibitors in existing breast cancer preclinical and clinical trials that elicits a robust immune response and benefit. Overall, the promising results observed in LSD1-targeting therapies signify the central role of epigenetics as a potential novel strategy to overcome resistance commonly seen in immunotherapies.

Antagonistic action of GPS2 and KDM1A at enhancers governs alternative macrophage activation by interleukin 4

The Th2 cytokine interleukin 4 (IL4) promotes macrophage differentiation into alternative subtypes and plays important roles in physiology, in metabolic and inflammatory diseases, in cancer and in tissue regeneration. While the regulatory transcription factor networks governing IL4 signaling are already well-characterized, it is currently less understood which transcriptional coregulators are involved and how they operate mechanistically. In this study, we discover that G protein pathway suppressor 2 (GPS2), a core subunit of the HDAC3 corepressor complex assembled by SMRT and NCOR, represses IL4-dependent enhancer activation in mouse macrophages. Our genome-wide and gene-specific characterization revealed that, instead of directly repressing STAT6, chromatin-bound GPS2 cooperates with SMRT and NCOR to antagonize enhancer activation by lysine demethylase 1A (KDM1A, LSD1). Mechanistically, corepressor depletion increased KDM1A recruitment to enhancers linked to IL4-induced genes, accompanied by demethylation of the repressive histone marks H3K9me2/3 without affecting H3K4me1/2, the classic KDM1A substrates for demethylation in other cellular contexts. This in turn caused enhancer and gene activation already in the absence of IL4/STAT6 and sensitized the STAT6-dependent IL4 responsiveness of macrophages. Thus, our work identified with the antagonistic action of a GPS2-containing corepressor complex and the lysine demethylase KDM1A a hitherto unknown epigenetic corepressor-coactivator switching mechanism that governs alternative macrophage activation.

Inhibition of lysine-specific demethylase 1 enhances the sensitivity of the chemotherapeutic drug doxorubicin in gastric cancer cell

AIM

Lysine-Specific Demethylase 1 (LSD1) inhibitors have been developed and reached the clinic, but its effect in combination with cytotoxic chemotherapy is unclear. Here, we investigated the anti-tumor effect of LSD1 inhibitor GSK-LSD1 and its anti-tumor effect with the DNA damage drug doxorubicin (DOX) in gastric cancer (GC) cells.

METHODS

Cells were treated with different concentrations of GSK-LSD1 to examine the anti-tumor effect versus cell viability by MTT and cell cycle arrest by flow cytometry. To explore whether LSD1 inhibitors can increase the anti-tumor effect of DNA damage drugs, cells were treated with DOX for 48 h after pretreatment with GSK-LSD1 for 48 h. Cell viability was detected by MTT and apoptosis-related proteins were examined by Western blot. Furthermore, anti-tumor efficacy of combination GSK-LSD1 with DOX was also measured in MGC-803 xenografts model in nude mice.

RESULTS

The results showed that LSD1 was highly expressed in GC cell lines. Inhibition of LSD1 has a weak effect on cell viability and cell cycle. Moreover, LSD1 inhibitors pretreatment could significantly increase the anti-tumor effect of DOX. Further study found that inhibition of LSD1 can significantly enhance DOX-induced the apoptosis, accompanied by down-regulation of antiapoptotic Bcl-2 expression and up-regulation of proapoptotic Bax expression. We also confirmed that inhibition of LSD1 can sensitize the anti-tumor effect of DOX in vivo.

CONCLUSION

Our findings suggest that the LSD1 inhibitor GSK-LSD1 has a weak inhibitory effect on the viability and cell cycle of GC cells, but can enhance the sensitivity of DOX.

Targeting the LSD1/KDM1 Family of Lysine Demethylases in Cancer and Other Human Diseases

Lysine-specific demethylase 1 (LSD1) was the first histone demethylase discovered and the founding member of the flavin-dependent lysine demethylase family (KDM1). The human KDM1 family includes KDM1A and KDM1B, which primarily catalyze demethylation of histone H3K4me1/2. The KDM1 family is involved in epigenetic gene regulation and plays important roles in various biological and disease pathogenesis processes, including cell differentiation, embryonic development, hormone signaling, and carcinogenesis. Malfunction of many epigenetic regulators results in complex human diseases, including cancers. Regulators such as KDM1 have become potential therapeutic targets because of the reversibility of epigenetic control of genome function. Indeed, several classes of KDM1-selective small molecule inhibitors have been developed, some of which are currently in clinical trials to treat various cancers. In this chapter, we review the discovery, biochemical, and molecular mechanisms, atomic structure, genetics, biology, and pathology of the KDM1 family of lysine demethylases. Focusing on cancer, we also provide a comprehensive summary of recently developed KDM1 inhibitors and related preclinical and clinical studies to provide a better understanding of the mechanisms of action and applications of these KDM1-specific inhibitors in therapeutic treatment.

Dual LSD1 and HDAC6 Inhibition Induces Doxorubicin Sensitivity in Acute Myeloid Leukemia Cells

Defects in epigenetic pathways are key drivers of oncogenic cell proliferation. We developed a LSD1/HDAC6 multitargeting inhibitor (iDual), a hydroxamic acid analogue of the clinical candidate LSD1 inhibitor GSK2879552. iDual inhibits both targets with IC₅₀ values of 540, 110, and 290 nM, respectively, against LSD1, HDAC6, and HDAC8. We compared its activity to structurally similar control probes that act by HDAC or LSD1 inhibition alone, as well as an inactive null compound. iDual inhibited the growth of leukemia cell lines at a higher level than GSK2879552 with micromolar IC₅₀ values. Dual engagement with LSD1 and HDAC6 was supported by dose dependent increases in substrate levels, biomarkers, and cellular thermal shift assay. Both histone methylation and acetylation of tubulin were increased, while acetylated histone levels were only mildly affected, indicating selectivity for HDAC6. Downstream gene expression (CD11b, CD86, p21) was also elevated in response to iDual treatment. Remarkably, iDual synergized with doxorubicin, triggering significant levels of apoptosis with a sublethal concentration of the drug. While mechanistic studies did not reveal changes in DNA repair or drug efflux pathways, the expression of AGPAT9, ALOX5, BTG1, HIPK2, IFI44L, and LRP1, previously implicated in doxorubicin sensitivity, was significantly elevated.

Antitumor Effect of Demethylzeylasteral (T-96) on Triple-Negative Breast Cancer via LSD1-Mediate Epigenetic Mechanisms

Background and Purpose. Breast cancer ranks first in the incidence of female tumors. Triple-negative breast cancer (TNBC), one type of breast cancer, is more aggressive and has a worse prognosis. Demethylzeylasteral (T-96) is isolated from Tripterygium wilfordii Hook F. Our previous study found that T96 could inhibit TNBC invasion via suppressing the canonical and noncanonical TGF-β signaling pathways. However, the antitumor effects and mechanisms of T-96 on TNBC have not been studied. This study is aimed at investigating the antitumor effect and mechanism of T-96 on breast cancer. Experimental approach. MTT assay, Live and Dead cell assay, and TUNEL were used to observe the antitumor effect of breast cancer cells treated with T-96. siRNA of LSD1, Co-IP, and molecular docking were used to explore the direct target and mechanism of T-96. Subcutaneous murine xenograft models were used to detect the efficacy of T-96 antitumor activity in vivo. Key Results. T-96 was more susceptible to inducing the apoptosis of highly metastatic TNBC cell lines (SUM-1315). An abnormal level of histone methylation is a crucial characteristic of metastatic cancer cells. LSD1 is a histone demethylase. We found that T-96 could significantly decrease the protein expression of LSD1, increase its target protein PTEN expression and enhance histone methylation. T-96 could also down-regulate the PI3K/AKT signaling pathway, which could be blocked by PTEN. Knockdown of LSD1 by siRNA blocked the pharmacological activity of T-96. And the molecular docking predicted T-96 processed affinity toward LSD1 through hydrogen bonding. Finally, T-96 was evaluated in a murine xenograft model of SUM-1315 cells. And T-96 could significantly inhibit tumor growth without showing marked toxicity. Conclusions & Implications. The results illustrated that T-96 exerted antitumor activity in highly metastatic TNBC by inactivating the LSD1 function.

Identification of novel indole derivatives as highly potent and efficacious LSD1 inhibitors

Lysine-specific demethylase 1 (LSD1) is a FAD-dependent histone demethylase to catalyze the demethylation of H3K4 and H3K9 and thus is an attractive target for therapeutic cancer. Starting with a high micromolar compound 17i, structure-based optimization of novel indole derivatives is described by a bioelectronic isosteric strategy. Grounded by molecular modeling, medicinal chemistry has efficiently yielded low nanomolar LSD1 inhibitors. One of the compounds, B35, exhibited excellent LSD1 inhibition (IC50 = 0.050 ± 0.005 μM) and anti-proliferation against A549 cells (IC50 = 0.74 ± 0.14 μM). The further PK studies indicated compound B35 possessed favorable metabolic stability, in which the plasma t1/2 of p.o. and i.v. were 6.27 ± 0.72 h and 8.78 ± 1.31 h, respectively. Additionally, inhibitor B35 shows a strong antitumor effect and good safety in vivo. Meanwhile, compound B35 regulated genes are closely associated with transcriptional dislocation in cancer and PI3K/AKT pathway involving IGFBP3. Taken together, B35 could be a potent LSD1 inhibitor for further drug development.

The Role of LSD1 and LSD2 in Cancers of the Gastrointestinal System: An Update

Epigenetic mechanisms are known to play a key role in cancer progression. Specifically, histone methylation involves reversible post-translational modification of histones that govern chromatin structure remodelling, genomic imprinting, gene expression, DNA damage repair, and meiotic crossover recombination, among other chromatin-based activities. Demethylases are enzymes that catalyse the demethylation of their substrate using a flavin adenine dinucleotide-dependent amine oxidation process. Lysine-specific demethylase 1 (LSD1) and its homolog, lysine-specific demethylase 2 (LSD2), are overexpressed in a variety of human cancer types and, thus, regulate tumour progression. In this review, we focus on the literature from the last 5 years concerning the role of LSD1 and LSD2 in the main gastrointestinal cancers (i.e., gastric cancer, liver cancer, pancreatic cancer, and colorectal cancer).