Lysyl Oxidase Family Research Articles

DEPLETION OF LYSYL OXIDASE-LIKE 4 (LOXL4) ATTENUATES COLONY FORMATION IN VITRO AND COLLAGEN DEPOSITION IN VIVO BREAST CANCER MODEL

Highlights Revealing LOX family members' mechanisms in promoting invasive breast cancer progression is essential for targeting specific molecules in invasive breast cancer. Depletion of LOXL4 in invasive breast cancer shows attenuation of cell invasiveness in vitro and collagen deposition in tumor models in vivo. Abstract Background: Lysyl oxidase (LOX) family proteins have recently become a topic in cancer progression. Our recent study found a high expression of LOX-like 4 (LOXL4) in MDA-MB-231 cells. Objective: To reveal the impact of depleted LOXL4 in both in vitro and in vivo breast cancer models from a histological perspective. Material and Method: Endogenous LOXL4 was depleted using the CRISPR/Cas9 on MDA-MB-231 parental cells. Based on the LOXL4 protein expression, the clone was determined for the next experiment, thus generating MDA-MB-231 LOXL4 KO. Cell assay was conducted using colony formation assay (n=3) followed by crystal violet staining. The indicated cells were inoculated orthotopically to female BALB/c nude mice (n=5). At the end of the experiment, tumors were isolated, fixed, and prepared for Masson Trichrome staining. Result: CRISPR/Cas9 completely depleted LOXL4 expression on clone number #2-22. Depletion of LOXL4 reduced the colony size formed by MDA-MB-231 cells. MDA-MB-231 LOXL4 KO #2-22 derived tumors showed depressed tumor volume compared to the parental group. Reduced collagen was also observed from the Masson Trichrome staining (p<0.001). Conclusion: Depletion of LOXL4 downregulates the growth of MDA-MB-231 cells in vitro and collagen deposition in vivo.

MiR-214–3p regulates Piezo1, lysyl oxidases and mitochondrial function in human cardiac fibroblasts

Cardiac fibroblasts are pivotal regulators of cardiac homeostasis and are essential in the repair of the heart after myocardial infarction (MI), but their function can also become dysregulated, leading to adverse cardiac remodelling involving both fibrosis and hypertrophy. MicroRNAs (miRNAs) are noncoding RNAs that target mRNAs to prevent their translation, with specific miRNAs showing differential expression and regulation in cardiovascular disease. Here, we show that miR-214–3p is enriched in the fibroblast fraction of the murine heart, and its levels are increased with cardiac remodelling associated with heart failure, or in the acute phase after experimental MI. Tandem mass tagging proteomics and in-silico network analyses were used to explore protein targets regulated by miR-214–3p in cultured human cardiac fibroblasts from multiple donors. Overexpression of miR-214–3p by miRNA mimics resulted in decreased expression and activity of the Piezo1 mechanosensitive cation channel, increased expression of the entire lysyl oxidase (LOX) family of collagen cross-linking enzymes, and decreased expression of an array of mitochondrial proteins, including mitofusin-2 (MFN2), resulting in mitochondrial dysfunction, as measured by citrate synthase and Seahorse mitochondrial respiration assays. Collectively, our data suggest that miR-214–3p is an important regulator of cardiac fibroblast phenotypes and functions key to cardiac remodelling, and that this miRNA represents a potential therapeutic target in cardiovascular disease.

Splicing factor hnRNPA1 regulates alternative splicing of LOXL2 to enhance the production of LOXL2Δ13

Lysyl oxidase-like 2 (LOXL2) is a member of the lysyl oxidase family and has the ability to catalyze the cross-linking of extracellular matrix collagen and elastin. High expression of LOXL2 is related to tumor cell proliferation, invasion and metastasis. LOXL2 contains 14 exons. Previous studies have found that LOXL2 has abnormal alternative splicing and exon skipping in a variety of tissues and cells, resulting in a new alternatively-spliced isoform denoted LOXL2Δ13. LOXL2Δ13 lacks LOXL2WT exon 13, but its encoded protein has greater ability to induce tumor cell proliferation, invasion and metastasis. However, the molecular events that produce LOXL2Δ13 are still unclear. In this study, we found that overexpression of the splicing factor hnRNPA1 in cells can regulate the alternative splicing of LOXL2 and increase the expression of LOXL2Δ13. The exonic splicing silencer (ESS) exists at the 3′ splice site (3′ SS) and 5′ splice site (5′ SS) of LOXL2 exon 13. HnRNPA1 can bind to the ESS and inhibit the inclusion of exon 13. The RRM domain of hnRNPA1 and phosphorylation of hnRNPA1 at S91 and S95 are important for the regulation of LOXL2 alternative splicing. These results show that hnRNPA1 is a splicing factor that enhances the production of LOXL2Δ13.

Crosstalk of lysyl oxidase-like 1 and lysyl oxidase prolongs their half-lives and regulates liver fibrosis through Notch signal.

Lysyl oxidase (LOX) family members (LOX and LOXL1 to 4) are crucial copper-dependent enzymes responsible for cross-linking collagen and elastin. Previous studies have revealed that LOX and LOXL1 are the most dramatically dysregulated LOX isoforms during liver fibrosis. However, the crosstalk between them and the underlying mechanisms involved in the profibrotic behaviors of HSCs, as well as the progression of liver fibrosis, remain unclear. pCol9GFP-HS4,5Tg mice, Loxl1fl/flGfapCre mice, human HSC line, and primary HSCs were enrolled to study the dysregulation pattern, profibrotic roles, and the potential mechanisms of LOX and LOXL1 interaction involved in the myofibroblast-like transition of HSCs and liver fibrogenesis. LOX and LOXL1 were synergistically upregulated during liver fibrogenesis, irrespective of etiology, together orchestrating the profibrotic behaviors of HSCs. LOX and LOXL1 coregulated in HSCs, whereas LOXL1 dominated in the coregulation loop. Interestingly, the interaction between LOXL1 and LOX prolonged their half-lives, specifically enhancing the Notch signal-mediated myofibroblast-like transition of HSCs. Selective disruption of Loxl1 in Gfap+ HSCs deactivated the Notch signal, inhibited HSC activation, and relieved carbon tetrachloride-induced liver fibrosis. Our current study confirmed the synergistic roles and the underlying mechanisms of LOXL1 and LOX crosstalk in the profibrotic behaviors of HSCs and liver fibrosis progression, providing experimental evidence for further clear mechanism-based anti-LOXL1 strategy development in the therapy of liver fibrosis.

Reactive Oxygen Species-Responsive Nanoparticles Toward Extracellular Matrix Normalization for Pancreatic Fibrosis Regression.

Pancreatic fibrosis (PF) is primarily characterized by aberrant production and degradation modes of extracellular matrix (ECM) components, resulting from the activation of pancreatic stellate cells (PSCs) and the pathological cross-linking of ECM mediated by lysyl oxidase (LOX) family members. The excessively deposited ECM increases matrix stiffness, and the over-accumulated reactive oxygen species (ROS) induces oxidative stress, which further stimulates the continuous activation of PSCs and advancing PF; challenging the strategy toward normalizing ECM homeostasis for the regression of PF. Herein, ROS-responsive and Vitamin A (VA) decorated micelles (named LR-SSVA) to reverse the imbalanced ECM homeostasis for ameliorating PF are designed and synthesized. Specifically, LR-SSVA selectively targets PSCs via VA, thereby effectively delivering siLOXL1 and resveratrol (RES) into the pancreas. The ROS-responsive released RES inhibits the overproduction of ECM by eliminating ROS and inactivating PSCs, meanwhile, the decreased expression of LOXL1 ameliorates the cross-linked collagen for easier degradation by collagenase which jointly normalizes ECM homeostasis and alleviates PF. This research shows that LR-SSVA is a safe and efficient ROS-response and PSC-targeted drug-delivery system for ECM normalization, which will propose an innovative and ideal platform for the reversal of PF.

LOXL1 promotes tumor cell malignancy and restricts CD8 + T cell infiltration in colorectal cancer

BackgroundColorectal cancer (CRC) is a leading cause of cancer mortality globally. Lymph node metastasis and immunosuppression are main factors of poor prognosis in CRC patients. Lysyl oxidase like 1 (LOXL1), part of the lysyl oxidase (LOX) family, plays a yet unclear role in CRC. This study aimed to identify effective biomarkers predictive of prognosis and efficacy of immunotherapy in CRC patients, and to elucidate the prognostic value, clinical relevance, functional and molecular features, and immunotherapy predictive role of LOXL1 in CRC and pan-cancer.MethodsWeighted gene co-expression network analysis (WGCNA) was employed to explore gene modules related to tumor metastasis and CD8 + T cell infiltration. LOXL1 emerged as a hub gene through differential gene expression and survival analysis. The molecular signatures, functional roles, and immunological characteristics affected by LOXL1 were analyzed in multiple CRC cohorts, cell lines and clinical specimens. Additionally, LOXL1's potential as an immunotherapy response indicator was assessed, along with its role in pan-cancer.ResultsTurquoise module in WGCNA analysis was identified as the hub module associated with lymph node metastasis and CD8 + T cell infiltration. Aberrant elevated LOXL1 expression was observed in CRC and correlated with poorer differentiation status and prognosis. Molecular and immunological characterization found that LOXL1 might mediate epithelial-mesenchymal transition (EMT) process and immunosuppressive phenotypes of CRC. Functional study found that LOXL1 enhanced tumor cell proliferation, migration and invasion. Moreover, high LOXL1 levels corresponded to reduced CD8 + T cell infiltration and predicted poor clinical outcomes of immunotherapy. Similar trends were also observed at the pan-cancer level.ConclusionsOur findings underscore the critical role of LOXL1 in modulating both malignancy and immunosuppression in CRC. This positions LOXL1 as a promising biomarker for predicting prognosis and the response to immunotherapy in CRC patients.Graphical

LOX, but not LOXL2, promotes bone metastasis formation and bone destruction in triple-negative breast cancer

The primary function of the lysyl oxidase (LOX) family, including LOX and its paralogue LOX-like (LOXL)-2, is to catalyze the covalent crosslinking of collagen and elastin in the extracellular matrix. LOX and LOXL2 are also facilitating breast cancer invasion and metastatic spread to visceral organs (lungs, liver) in vivo. Conversely, the contribution of LOX and LOXL2 to breast cancer bone metastasis remains scant. Here, using gene overexpression or silencing strategies, we investigated the role of LOX and LOXL2 on the formation of metastatic osteolytic lesions in animal models of triple negative breast cancer. In vivo, the extent of radiographic metastatic osteolytic lesions in animals injected with LOX-overexpressing [LOX(+)] tumor cells was 3-fold higher than that observed in animals bearing tumors silenced for LOX [LOX(−)]. By contrast, the extent of osteolytic lesions between LOXL2(+) and LOXL2(−) tumor-bearing animals did not differ, and was comparable to that observed with LOX(−) tumor-bearing animals. In situ, TRAP staining of bone tissue sections from the hind limbs of LOX(+) tumor-bearing animals was substantially increased compared to LOX(−), LOXL2(+) and LOXL2(−)-tumor-bearing animals, which was indicative of enhanced active-osteoclast resorption. In vitro, tumor-secreted LOX increased osteoclast differentiation induced by RANKL, whereas LOXL2 seemed to counteract LOX’s pro-osteoclastic activity. Furthermore, LOX (but not LOXL2) overexpression in tumor cells induced a robust production of IL-6, the latter being a pro-osteoclastic cytokine. Based on these findings, we propose a model in which LOX and IL-6 secreted from tumor cells act in concert to enhance osteoclast-mediated bone resorption that, in turn, promotes metastatic bone destruction in vivo.

Pan-Cancer Analysis of the LOX Family Reveals that LOX Affects Tumor Prognosis by Affecting Immune Infiltration.

The lysyl oxidase (LOX) gene family encodes for a group of copper-dependent enzymes that play a crucial role in the cross-linking of collagen and elastin fibers in the extracellular matrix (ECM). Dysregulation of LOX gene expression has been implicated in various pathological conditions, including cancer. Several studies have shown that the LOX gene family is involved in cancer progression and metastasis. The goal of this article is to conduct a comprehensive analysis of the LOX family's role in pan-cancer multiplexes. We utilized pan-cancer multi-omics sequencing data from TCGA to investigate the relationship between LOX family genes and tumors at four different levels: mutation, copy number variation, methylation, and gene expression. In addition, we also examined the relationship between LOX family genes and tumors at the cell line level using tumor cell line sequencing data from CCLE. Taking into account the impact of LOX family genes on lung cancer, we developed a LOX family lung cancer prognostic model to forecast the disease's prognosis. Our findings revealed that LOXL2 had the highest mutation frequency in tumors, while all four LOX family genes experienced some degree of copy number variation in diverse tumors. We observed that LOX, LOXL1 to LOXL3 were predominantly highly expressed in tumors including LUAD. The expression trends of LOX and LOXL1 to LOXL3 were consistent across tumor cell lines, but differed somewhat from LOXL4. Utilizing 25 LOX family-related genes, we constructed a LOX family prognostic model that performed well in predicting the prognosis of lung cancer. Through pan-cancer analysis, we gain further knowledge of the role of LOX family genes in different tumors, offering a novel pathway for future research into the relationship between LOX family genes and tumors.

Lysyl Oxidase (LOX) Family Proteins: Key Players in Breast Cancer Occurrence and Progression.

The lysyl oxidase (LOX) family proteins are secreted copper-dependent amine oxidases, comprised of five paralogues: LOX and LOX-like 1-4 (LOXL1-4), which are characterized by catalytic activity contributing to the remodeling of the cross-linking of the structural extracellular matrix (ECM). ECM remodeling plays a key role in the angiogenesis surrounding tumours, whereby a corrupt tumour microenvironment (TME) takes shape. Additionally, dysregulation and aberrant expression of LOX family proteins have been implicated in the occurrence and progression of various types of human cancers, including lung cancer, hepatocellular carcinoma, gastric cancer, renal cell carcinoma, and colorectal cancer. Breast cancer is the most prevalent malignant tumour in women worldwide, and its incidence rate is increasing annually. In recent years, a growing body of evidence has revealed significant upregulation of LOX family proteins in breast cancer, which contributes to cancer cell proliferation, invasion, and metastasis. Furthermore, elevated expression of LOX family proteins is closely associated with poor prognosis in breast cancer patients. We herein review the structure, regulation, function, and mechanisms of LOX family proteins in the occurrence and progression of breast cancer. In addition, we highlight recent insights into their mechanisms and their potential involvement in the clinical value and novel biological roles of LOX family members in tumour progression and the TME of breast cancer. This review will provide a theoretical basis and reference for clinical diagnosis and treatment of breast cancer, as well as for the screening of effective LOX-specific inhibitors.

Copper chelation reduces early collagen deposition and preserves saliva secretion in irradiated salivary glands

Radiation therapy is a first-line treatment for head and neck cancer; however, it typically leads to hyposalivation stemming from fibrosis of the salivary gland. Current strategies to restore glandular function are dependent on the presence of residual functional salivary gland tissue, a condition commonly not met in patients with extensive fibrotic coverage of the salivary gland resulting from radiation therapy. Fibrosis is defined by the pathological accumulation of connective tissue (i.e., extracellular matrix) and excessive deposition of crosslinked (fibrillar) collagen that can impact a range of tissues and given that collagen crosslinking is necessary for fibrosis formation, inhibiting this process is a reasonable focus for developing anti-fibrotic therapies. Collagen crosslinking is catalyzed by the lysyl oxidase family of secreted copper-dependent metalloenzymes, and since that copper is an essential cofactor in all lysyl oxidase family members, we tested whether localized delivery of a copper chelator into the submandibular gland of irradiated mice could suppress collagen deposition and preserve the structure and function of this organ. Our results demonstrate that transdermal injection of tetrathiomolybdate into salivary glands significantly reduced the early deposition of fibrillar collagen in irradiated mice and preserved the integrity and function of submandibular gland epithelial tissue. Together, these studies identify copper metabolism as a novel therapeutic target to control radiation induced damage to the salivary gland and the current findings further indicate the therapeutic potential of repurposing clinically approved copper chelators as neoadjuvant treatments for radiation therapy.

The possibilities of LOXL4 as a prognostic marker for carcinomas.

Lysyl oxidase-like 4 (LOXL4), a member of lysyl oxidase family, is a copper and lysine tyrosylquinone-dependent amine oxidase that serves the role of catalyzing the cross-linking of elastin and collagen in the extracellular matrix. Numerous studies have shown a significant association between LOXL4 expression levels and tumor proliferation, migration, invasion and patients' prognosis and overall survival in different types of tumors. Here we review their relationship and the molecular pathogenesis behind them, aiming to explore the possibilities of LOXL4 as a prognostic marker for diverse carcinomas and provide some indications for further research in this field.

LOXL2 in Cancer: A Two-Decade Perspective.

Lysyl Oxidase Like 2 (LOXL2) belongs to the lysyl oxidase (LOX) family, which comprises five lysine tyrosylquinone (LTQ)-dependent copper amine oxidases in humans. In 2003, LOXL2 was first identified as a promoter of tumour progression and, over the course of two decades, numerous studies have firmly established its involvement in multiple cancers. Extensive research with large cohorts of human tumour samples has demonstrated that dysregulated LOXL2 expression is strongly associated with poor prognosis in patients. Moreover, investigations have revealed the association of LOXL2 with various targets affecting diverse aspects of tumour progression. Additionally, the discovery of a complex network of signalling factors acting at the transcriptional, post-transcriptional, and post-translational levels has provided insights into the mechanisms underlying the aberrant expression of LOXL2 in tumours. Furthermore, the development of genetically modified mouse models with silenced or overexpressed LOXL2 has enabled in-depth exploration of its in vivo role in various cancer models. Given the significant role of LOXL2 in numerous cancers, extensive efforts are underway to identify specific inhibitors that could potentially improve patient prognosis. In this review, we aim to provide a comprehensive overview of two decades of research on the role of LOXL2 in cancer.

A first-in-class pan-lysyl oxidase inhibitor impairs stromal remodeling and enhances gemcitabine response and survival in pancreatic cancer.

The lysyl oxidase family represents a promising target in stromal targeting of solid tumors due to the importance of this family in crosslinking and stabilizing fibrillar collagens and its known role in tumor desmoplasia. Using small-molecule drug-design approaches, we generated and validated PXS-5505, a first-in-class highly selective and potent pan-lysyl oxidase inhibitor. We demonstrate in vitro and in vivo that pan-lysyl oxidase inhibition decreases chemotherapy-induced pancreatic tumor desmoplasia and stiffness, reduces cancer cell invasion and metastasis, improves tumor perfusion and enhances the efficacy of chemotherapy in the autochthonous genetically engineered KPC model, while also demonstrating antifibrotic effects in human patient-derived xenograft models of pancreatic cancer. PXS-5505 is orally bioavailable, safe and effective at inhibiting lysyl oxidase activity in tissues. Our findings present the rationale for progression of a pan-lysyl oxidase inhibitor aimed at eliciting a reduction in stromal matrix to potentiate chemotherapy in pancreatic ductal adenocarcinoma.

Abstract P2042: Linking Extracellular Matrix Stiffness With Cardiomyocyte Structure And Function

The composition and organization of the extracellular matrix (ECM) provides cues to myocardial cells that direct normal function and responses to stress. However, little is known about how exactly a change in environmental tension leads to alterations in cardiomyocyte cell size and contractile force. Collagen I comprises the majority of cardiac ECM where it is crosslinked and matured by the lysyl oxidase (LOX) family of enzymes that includes LOX and LOX-like (LOXL) proteins. LOX and LOXLs are frequently upregulated in the heart after injury, and their inhibition has been shown to alleviate increases in tissue stiffness. Cardiac injury models result in activation and recruitment of many cells that secrete growth factors and modify the ECM, which makes it difficult to address specifically how cardiomyocytes are responding to changes in matrix tension alone. Therefore, we utilized LOX or LOXL overexpression as a tool to stiffen the ECM in the absence of pathophysiologic injury and paracrine factors. Transgenic overexpression of LOX increases myocardial stiffness and results in mild cardiac dysfunction by 9 months of age. While younger adult mice do not display a phenotype at baseline, they have an exaggerated response to pressure overload hypertrophy. In a different set of experiments, adeno-associated viruses (AAV9) for LOXL1, -2, or -3 were administered to mouse pups via cardiac injection at perinatal day 7. By 12 weeks of age, LOXL1 overexpression leads to cardiac hypertrophy with preserved ejection fraction, while increased LOXL2 or LOXL3 results in decreased cardiac function (each with differential patterns of myocardial fibrosis). Ongoing studies are assessing how these functional changes are associated with alterations in tissue stiffness and cardiomyocyte behavior. Determining how cardiomyocytes respond to alterations in the physical properties of the ECM will improve our understanding of the etiology of progressive cardiomyopathies and fibrosis.

Deciphering transcriptional dynamics of cardiac hypertrophy and failure in a chamber-specific manner.

Pressure overload-induced pathological cardiac hypertrophy (CH) is a complexed and adaptive remodeling of the heart, predominantly involving an increase in cardiomyocyte size and thickening of ventricular walls. Over time, these changes can lead to heart failure (HF). However, the individual and shared biological mechanisms of both processes remain poorly understood. This study aimed to identify key genes and signaling pathways associated with CH and HF following aortic arch constriction (TAC) at four weeks and six weeks, respectively, and to investigate potential underlying molecular mechanisms in this dynamic transition from CH to HF at the whole cardiac transcriptome level. Initially, a total of 363, 482, and 264 differentially expressed genes (DEGs) for CH, and 317, 305, and 416 DEGs for HF were identified in the left atrium (LA), left ventricle (LV), and right ventricle (RV), respectively. These identified DEGs could serve as biomarkers for the two conditions in different heart chambers. Additionaly, two communal DEGs, elastin (ELN) and hemoglobin beta chain-beta S variant (HBB-BS), were found in all chambers, with 35 communal DEGs in the LA and LV and 15 communal DEGs in the LV and RV in both CH and HF. Functional enrichment analysis of these genes emphasized the crucial roles of the extracellular matrix and sarcolemma in CH and HF. Lastly, three groups of hub genes, including the lysyl oxidase (LOX) family, fibroblast growth factors (FGF) family, and NADH-ubiquinone oxidoreductase (NDUF) family, were determined to be essential genes of dynamic changes from CH to HF.

Levoleucovorin inhibits LOXL2 (lysyl oxidase like-2) to control breast cancer proliferation: a repurposing approach

Lysyl oxidase like-2 (LOXL2) belongs to copper dependent amine oxidase from the lysyl oxidase family and is associated with breast cancer metastasis This study used multi-stage computational screening and in vitro validations to repurpose FDA approved drugs targeting LOXL2 to control breast cancer progression.Molecular modeling techniques and high-throughput virtual-screening technique was employed to screen FDA-approved drug library for its avid binding to LOXL2.hLOXL2, MDA-MB231 and MCF 7 cells were used for in vitro.Collectively, this repurposing study identified levoleucovorin to bind the active site of LOXL2 protein to inhibit its activity. Further validation of levoleucovorin against LOXL2 activity is warranted toward repurposing levoleucovorin as a therapeutic agent for treating breast cancer patients. validations.Computational modeling of LOXL2 identified putative druggable region at the active site of LOXL2 protein. High-throughput virtual screening predicted levoleucovorin as a best lead drug candidate to have a favorable binding affinity for LOXL2 at its active site. Molecular dynamic simulation predicts levoleucovorin to bind stably and avidly to LOXL2 with favorable interactions. In vitro validations show levoleucovorin significantly inhibited hLOXL2 with and IC50 value of 68.81 μM. Levoleucovorin controlled cell proliferations in MDM-MB 231 and MCF-7 cells with GI50 values of 55.91 μM and 79.20 μM respectively. Further, a dose dependent inhibition of cancer cell migration was noted along with apoptosis induction in these cells with levoleucovorin treatment. Communicated by Ramaswamy H. Sarma

Myocardin-related transcription factor contributes to renal fibrosis through the regulation of extracellular microenvironment surrounding fibroblasts.

Fibroblast accumulation and extracellular matrix (ECM) deposition are common critical steps for the progression of organ fibrosis, but the precise molecular mechanisms remain to be fully investigated. We have previously demonstrated that lysophosphatidic acid contributes to organ fibrosis through the production of connective tissue growth factor (CTGF) via actin cytoskeleton-dependent signaling, myocardin-related transcription factor family (MRTF) consisting of MRTF-A and MRTF-B-serum response factor (SRF) pathway. In this study, we investigated the role of the MRTF-SRF pathway in the development of renal fibrosis, focusing on the regulation of ECM-focal adhesions (FA) in renal fibroblasts. Here we showed that both MRTF-A and -B were required for the expressions of ECM-related molecules such as lysyl oxidase family members, type I procollagen and fibronectin in response to transforming growth factor (TGF)-β1 . TGF-β1 -MRTF-SRF pathway induced the expressions of various components of FA such as integrin α subunits (αv , α2 , α11 ) and β subunits (β1 , β3 , β5 ) as well as integrin-linked kinase (ILK). On the other hand, the blockade of ILK suppressed TGF-β1 -induced MRTF-SRF transcriptional activity, indicating a mutual relationship between MRTF-SRF and FA. Myofibroblast differentiation along with CTGF expression was also dependent on MRTF-SRF and FA components. Finally, global MRTF-A deficient and inducible fibroblast-specific MRTF-B deficient mice (MRTF-AKO BiFBKO mice) are protected from renal fibrosis with adenine administration. Renal expressions of ECM-FA components and CTGF as well as myofibroblast accumulation were suppressed in MRTF-AKO BiFBKO mice. These results suggest that the MRTF-SRF pathway might be a therapeutic target for renal fibrosis through the regulation of components forming ECM-FA in fibroblasts.

The Expression Pattern and Clinical Significance of Lysyl Oxidase Family in Gliomas.

LOX (Lysyl oxidase) family participates in the catalysis of collagen and elastin to maintain ECM homeostasis. Glioma is the most common primary brain tumor and LOX family has not been systemic studied in glioma. In this study, we found LOX family members are upregulated expressed in gliomas samples. A protein-protein interaction network (PPIN) was construct to visualize and understand the differential expression pattern, as well as functional annotation, for LOX family and their interacting proteins, which involved in collagen fibril organization and MAPK signaling pathway. Through subcellular localization distribution, the LOX family members distribute both intracellular and extracellular. All five LOX members are consistently significantly correlate with dendritic cell both in immune infiltrate of GBM and LGG. Survival analysis showed that high expression of LOX family is associated with a poor prognosis of gliomas patients. These analyses provide important clues to identify the potential biological roles for LOX family in gliomas, which might serve as diagnosis markers.

Lysyl oxidase-like 3 restrains mitochondrial ferroptosis to promote liver cancer chemoresistance by stabilizing dihydroorotate dehydrogenase

To overcome chemotherapy resistance, novel strategies sensitizing cancer cells to chemotherapy are required. Here, we screen the lysyl-oxidase (LOX) family to clarify its contribution to chemotherapy resistance in liver cancer. LOXL3 depletion significantly sensitizes liver cancer cells to Oxaliplatin by inducing ferroptosis. Chemotherapy-activated EGFR signaling drives LOXL3 to interact with TOM20, causing it to be hijacked into mitochondria, where LOXL3 lysyl-oxidase activity is reinforced by phosphorylation at S704. Metabolic adenylate kinase 2 (AK2) directly phosphorylates LOXL3-S704. Phosphorylated LOXL3-S704 targets dihydroorotate dehydrogenase (DHODH) and stabilizes it by preventing its ubiquitin-mediated proteasomal degradation. K344-deubiquitinated DHODH accumulates in mitochondria, in turn inhibiting chemotherapy-induced mitochondrial ferroptosis. CRISPR-Cas9-mediated site-mutation of mouse LOXL3-S704 to D704 causes a reduction in lipid peroxidation. Using an advanced liver cancer mouse model, we further reveal that low-dose Oxaliplatin in combination with the DHODH-inhibitor Leflunomide effectively inhibit liver cancer progression by inducing ferroptosis, with increased chemotherapy sensitivity and decreased chemotherapy toxicity.

Abstract 2605: LOXL3 knock out affects pathways which involve cytoskeleton regulation, proliferation and apoptosis in glioblastoma cells

Abstract Lysyl oxidase-like 3 (LOXL3), belonging to the lysyl oxidase family of copper-dependent amino oxidase, is responsible for the crosslinking of collagen and elastin. In tumors, the presence of LOXL3 has been associated with genomic stability, cell proliferation, and metastasis. In silico analysis has shown that glioblastoma was among the tumors with the highest LOXL3 expression levels. Moreover, LOXL3 expression increased with malignancy grade amongst diffusely infiltrative astrocytomas (from grade 2 to 4). In the present work, CRISPR-Cas9 gene editing was used to knock out LOXL3 in the human glioma U87MG cell line to evaluate the role of LOXL3 in glioblastoma. Analyses of protein expression level and genomic mutation mediated by CRISPR-Cas9 by two different sgRNA (denominated sgRNA1 and 2) were performed and the knock out efficiency and genome editing were confirmed. Transcriptome analysis of these cells revealed a downregulation of genes that coded for proteins involved in microtubule organization, cell division, and vesicle trafficking. On the other hand, upregulated genes when LOXL3 was knocked out in U87MG cells were involved in actin cytoskeleton, negative regulation of gene transcription, including chromatin remodeling, and cell-cell adhesion. Functional in vitro assays showed that LOXL3 knocked out cells presented decreased cell proliferation due to longer cell cycles with increased G1 and G2/M checkpoints compared to control cells. Additionally, LOXL3 knocked out U87MG cells presented a higher percentage of cells in the early phase of apoptosis with an increment after temozolomide treatment. Our results suggest an important role of LOXL3 in glioblastoma possibly mediated by cytoskeleton regulation, affecting cell proliferation, cell cycle, and cell death. These results reinforced the importance of LOXL3 in tumors, especially in glioblastoma, highlighting it as a potential therapeutic target. Citation Format: Talita S. Laurentino, Roseli S. Soares, Antonio M. Lerario, Suely K. Marie, Sueli Mieko Oba-Shinjo. LOXL3 knock out affects pathways which involve cytoskeleton regulation, proliferation and apoptosis in glioblastoma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2605.