Lysyl Oxidase-like 2 Research Articles

ERO1A levels are a prognostic indicator in EGFR mutated non small cell lung cancer

We have identified endoplasmic reticulum oxidoreductase 1 alpha (ERO1A) as a poor prognostic indicator in epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer (EGFRMUT-NSCLC). In addition, comparison of high versus low ERO1A expression among cohorts of EGFRMUT-NSCLC primary samples revealed that ERO1A expression correlated with increased expression of proteins that regulate secretion. Using the CPTAC proteomic data set in lung adenocarcinoma we found that high ERO1A protein expression correlated with both extracellular matrix and matrix modifying enzymes. In this report, we found that ablating ERO1A expression was a determinant of clonogenicity, tumor sphere formation, spheroid growth and growth in vivo, as well as response to Osimertinib. We validated that ERO1A-knockout EGFRMUT-LUAD cell lines demonstrated a reduction in secretion of both laminin gamma 2 (LAMC2) and the collagen modifying enzyme lysyl oxidase-like 2 (LOXL2). Our work supports the role of ERO1A in modulating the tumor microenvironment that is likely to contribute to tumor progression.

SiLOXL2 Inhibits Endothelial Inflammatory Response and EndMT Induced by ox-LDL

Introduction: Our research aimed to investigate the potential role and mechanism of lysyl oxidase (LOX)-like 2 (LOXL2) in atherosclerosis (AS) by using the human umbilical vein endothelial cells (HUVECs) stimulated by oxidized low-density lipoprotein (ox-LDL). Methods: HUVECs were treated with ox-LDL at different concentrations (0, 10, 25, 50, and 100 μg/mL) and incubated for 24 h. The transfection efficacy of siLOXL2 was investigated by Western blot and real-time quantitative polymerase chain reaction (RT-qPCR). Cell migration, intracellular ROS measurement, oxidative stress, enzyme-linked immunosorbent assay, and adhesion assays were carried out to examine the ox-LDL-induced HUVECs injury. RT-qPCR and Western blot were used to determine gene and protein expression levels. Results: LOXL2 protein expression increased in ox-LDL-induced endothelial cells (ECs). ox-LDL + siLOXL2 significantly inhibited the migration ability of HUVECs and reduced the expression of vascular endothelial growth factor A (VEGFA) and matrix metalloproteinase 9 gene expressions (all, p < 0.05). The ox-LDL + siLOXL2 significantly reduced intracellular ROS production and inhibited the expression of Malondialdehyde, whereas it markedly enhanced superoxide dismutase and catalase (all, p < 0.05). Supernatant levels of interleukin-1 beta (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) were significantly attenuated by the ox-LDL + siLOXL2 treatment (all, p < 0.05). ox-LDL + siLOXL2 markedly suppressed the expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 (all, p < 0.05). ox-LDL + siLOXL2 treatment remarkably reduced the expression of α-smooth muscle actin and vimentin, while increased CD31 and von Willebrand factor gene expression (all, p < 0.05). Conclusion: LOXL2 silencing is protected against ox-LDL-induced EC dysfunction, and the mechanism may be related to the inhibition of the EndMT pathway.

Pulling the Rug Out from Under: Biomechanical Microenvironment Remodeling for Induction of Hepatic Stellate Cell Quiescence.

Hepatic fibrosis progresses concomitantly with a variety of biomechanical alternations, especially increased liver stiffness. These biomechanical alterations have long been considered as pathological consequences. Recently, growing evidence proposes that these alternations result in the fibrotic biomechanical microenvironment, which drives the activation of hepatic stellate cells (HSCs). Here, an inorganic ascorbic acid-oxidase (AAO) mimicking nanozyme loaded with liquiritigenin (LQ) is developed to trigger remodeling of the fibrotic biomechanical microenvironment. The AAO mimicking nanozyme is able to consume intracellular ascorbic acid, thereby impeding collagen I deposition by reducing its availability. Simultaneously, LQ inhibits the transcription of lysyl oxidase like 2 (LOXL2), thus impeding collagen I crosslinking. Through its synergistic activities, the prepared nanosystem efficiently restores the fibrotic biomechanical microenvironment to a near-normal physiological condition, promoting the quiescence of HSCs and regression of fibrosis. This strategy of remodeling the fibrotic biomechanical microenvironment, akin to "pulling the rug out from under", effectively treats hepatic fibrosis in mice, thereby highlighting the importance of tissue biomechanics and providing a potential approach to improve hepatic fibrosis treatment.

Sex differences and role of lysyl oxidase-like 2 in angiotensin II-induced hypertension in mice.

Hypertension, a disease with known sexual dimorphism, accelerates aging-associated arterial stiffening, partly because of the activation of matrix remodeling caused by increased biomechanical load. In this study, we tested the effect of biological sex and the role of the matrix remodeling enzyme lysyl oxidase-like 2 (LOXL2) in hypertension-induced arterial stiffening. Hypertension was induced by angiotensin II (ANG II) infusion via osmotic minipumps in 12- to 14-wk-old male and female mice. Blood pressure and pulse wave velocity (PWV) were measured noninvasively. Wire myography and uniaxial tensile testing were used to test aortic vasoreactivity and mechanical properties. Aortic wall composition was examined by histology and Western blotting. Uniaxial stretch of cultured cells was used to evaluate the effect of biomechanical strain. LOXL2's catalytic function was examined using knockout and inhibition. ANG II infusion-induced hypertension in both genotypes and sexes. Wild-type (WT) males exhibited arterial stiffening in vivo and ex vivo. Aortic remodeling with increased wall thickness, intralamellar distance, higher LOXL2, and collagen I and IV content was noted in WT males. Female mice did not exhibit increased PWV despite the onset of hypertension. LOXL2 depletion improved vascular reactivity and mechanics in hypertensive males. LOXL2 depletion improved aortic mechanics but worsened hypercontractility in females. Hypertensive cyclic strain contributed to LOXL2 upregulation in the cell-derived matrix in vascular smooth muscle cells (VSMCs) but not endothelial cells. LOXL2's catalytic function facilitated VSMC alignment in response to biomechanical strain. In conclusion, in males, arterial stiffening in hypertension is driven both by VSMC response and matrix remodeling. Females are protected from PWV elevation in hypertension. LOXL2 depletion is protective in males with improved mechanical and functional aortic properties. VSMCs are the primary source of LOXL2 in the aorta, and hypertension increases LOXL2 processing and shifts to collagen I accumulation. Overall, LOXL2 depletion offers protection in young hypertensive males and females.NEW & NOTEWORTHY We examined the effect of sex on the evolution of angiotensin II (ANG II)-induced hypertension and the role of lysyl oxidase-like 2 (LOXL2), an enzyme that catalyzes matrix cross linking. While ANG II led to hypertension and worsening vascular reactivity in both sexes, aortic remodeling and stiffening occurred only in males. LOXL2 depletion improved outcomes in males but not females. Thus males and females exhibit a distinct etiology of hypertension and LOXL2 is an effective target in males.

Serum LOXL2 is Elevated and an Independent Biomarker in Patients with Coronary Artery Disease.

Arterial stiffness is associated with accelerated progression of atherosclerosis and plaque rupture. Lysyl oxidase-like 2 (LOXL2) plays a vital role in inflammatory responses, matrix deposition and arterial stiffness. This study assessed the correlation between the serum LOXL2 concentration and disease severity, inflammation, and endothelial dysfunction of coronary artery disease (CAD). The study included 143 CAD patients and 150 non-CAD patients who underwent coronary angiography. Medical records, demographic and clinical baseline parameters were collected. Serum LOXL2 levels were measured using an ELISA kit. CAD patients had higher serum LOXL2 levels than non-CAD patients, and LOXL2 levels were associated with severity of coronary lesions. Serum LOXL2 level was positively correlated with low-density lipoprotein cholesterol (LDL-C) (r=0.161, P=0.054), systolic blood pressure (SBP) (r=0.175, P=0.036), high-sensitivity C-reactive protein (hs-CRP) (r=0.177, P=0.035), intima-media thickness (IMT) (r=0.190, P=0.023), and brachial-ankle pulse wave velocity (baPWV) (r=0.203, P=0.015), while negatively associated with high-density lipoprotein cholesterol (HDL-C) (r=-0.191, P=0.023) and flow-mediated dilation (FMD) (r=-0.183, P=0.028) in CAD patients. Multivariate logistic regression showed that LOXL2 is independently correlated with LDL-C (OR=3.380; 95% CI=1.258-9.082; P=0.016), hs-CRP (OR=10.988; 95% CI=1.962-61.532; P=0.006), TC (OR=2.229; 95% CI=1.005-4.944; P=0.049), IMT (OR=72.719; 95% CI=2.313-2286.008; P=0.015), and baPWV (OR=1.002; 95% CI=1.001-1.004; P=0.005) in CAD patients. The receiver operating characteristic (ROC) curve showed that the best cut-off for CAD as serum LOXL2 is 275.35 pg/mL, with sensitivity and specificity of 77.6% and 84%, respectively. Our data demonstrated that LOXL2 could be a potential biomarker and independent risk factor for CAD patients.

Spatial transcriptomic validation of a biomimetic model of fibrosis enables re-evaluation of a therapeutic antibody targeting LOXL2

Matrix stiffening by lysyl oxidase-like 2 (LOXL2)-mediated collagen cross-linking is proposed as a core feedforward mechanism that promotes fibrogenesis. Failure in clinical trials of simtuzumab (the humanized version of AB0023, a monoclonal antibody against human LOXL2) suggested that targeting LOXL2 may not have disease relevance; however, target engagement was not directly evaluated. We compare the spatial transcriptome of active human lung fibrogenesis sites with different human cell culture models to identify a disease-relevant model. Within the selected model, we then evaluate AB0023, identifying that it does not inhibit collagen cross-linking or reduce tissue stiffness, nor does it inhibit LOXL2 catalytic activity. In contrast, it does potently inhibit angiogenesis consistent with an alternative, non-enzymatic mechanism of action. Thus, AB0023 is anti-angiogenic but does not inhibit LOXL2 catalytic activity, collagen cross-linking, or tissue stiffening. These findings have implications for the interpretation of the lack of efficacy of simtuzumab in clinical trials of fibrotic diseases.

LOXL2 inhibition ameliorates pulmonary artery remodeling in pulmonary hypertension.

Conduit pulmonary arterial stiffening and the resultant increase in pulmonary vascular impedance have emerged as an important underlying driver of pulmonary arterial hypertension (PAH). Given that matrix deposition is central to vascular remodeling, we evaluated the role of the collagen cross-linking enzyme lysyl oxidase like 2 (LOXL2) in this study. Human pulmonary artery smooth muscle cells (PASMCs) subjected to hypoxia showed increased LOXL2 secretion. LOXL2 activity and expression were markedly higher in primary PASMCs isolated from the pulmonary arteries of the rat Sugen 5416 + hypoxia (SuHx) model of severe pulmonary hypertension (PH). Similarly, LOXL2 protein and mRNA levels were increased in the pulmonary arteries (PA) and lungs of rats with PH (SuHx and monocrotaline (MCT) models). Pulmonary arteries (PAs) isolated from the rats with PH exhibited hypercontractility to phenylephrine and attenuated vasorelaxation elicited by acetylcholine, indicating severe endothelial dysfunction. Tensile testing revealed a significant increase in PA stiffness in PH. Treatment with PAT-1251, a novel small-molecule LOXL2 inhibitor, improved active and passive properties of the PA ex vivo. There was an improvement in right heart function as measured by right ventricular pressure volume loops in vivo with PAT-1251. Importantly, PAT-1251 treatment ameliorated PH, resulting in improved pulmonary artery pressures, right ventricular remodeling, and survival. Hypoxia-induced LOXL2 activation is a causal mechanism in pulmonary artery stiffening in PH and pulmonary artery mechanical and functional decline. LOXL2 inhibition with PAT-1251 could be a promising approach to improve pulmonary artery pressures, right ventricular elastance, cardiac relaxation, and survival in PAH.NEW & NOTEWORTHY Pulmonary arterial stiffening contributes to the progression of PAH and the deterioration of right heart function. This study shows that LOXL2 is upregulated in rat models of PH. LOXL2 inhibition halts pulmonary vascular remodeling and improves PA contractility, endothelial function, and PA pressure, resulting in prolonged survival. Thus, LOXL2 is an important mediator of PA remodeling and stiffening in PH and a promising target to improve PA pressures and survival in PH.

Tumor-Intrinsic Perinuclear LOXL2: Prognostic Relevance and Relationship with YAP1 Activation Status in Oral Squamous Cell Carcinoma.

Lysyl oxidase-like 2 (LOXL2) expression and function is frequently altered in different cancers but scarcely explored in oral squamous cell carcinoma (OSCC). This prompted us to investigate the clinical relevance of LOXL2 expression pattern in OSCC and also a possible crosstalk with Hippo/YAP1 pathway signaling. Immunohistochemical analysis of LOXL2 protein expression was performed in 158 OSCC patient samples, together with Yes-associated protein 1 (YAP1) activation status. Correlations with clinicopathological parameters and patient survival were assessed. Tumor cell-intrinsic LOXL2 expression showed two distinct expression patterns: diffuse cytoplasmic staining (64.6%) and heterogeneous perinuclear staining (35.4%). Remarkably, perinuclear LOXL2 staining was significantly associated with lymph node metastasis, advanced clinical stage and perineural invasion. Moreover, patients harboring tumors with perinuclear LOXL2 expression exhibited significantly poorer disease-specific survival (DSS) rates, and perinuclear LOXL2 positivity gradually increased in relation to YAP1 activation. Patients harboring tumors with concomitant perinuclear LOXL2 and fully active YAP1 exhibited the worst DSS. Multivariate Cox analysis further revealed combined perinuclear LOXL2 and fully active YAP1 as a significant independent predictor of poor DSS. Tumor-intrinsic perinuclear LOXL2 emerges as a clinically and biologically relevant feature associated with advanced disease, tumor aggressiveness, and poor prognosis in OSCC. Moreover, this study unprecedentedly uncovers a functional relationship between perinuclear LOXL2 and YAP1 activation with major prognostic implications. Notably, combined perinuclear LOXL2 and fully active YAP1 was revealed as independent predictor of poor prognosis. These findings encourage targeting oncogenic LOXL2 functions for personalized treatment regimens.

Sex Differences and Role of Lysyl Oxidase Like 2 (LOXL2) in Angiotensin II-Induced Hypertension in Mice.

Hypertension, a disease with known sexual dimorphism, accelerates aging associated arterial stiffening, in part due to the activation of matrix remodeling caused by increased biomechanical load. In this study, we tested the effect of biological sex and the role of the matrix remodeling enzyme lysyl oxidase like 2 (LOXL2) in hypertension induced arterial stiffening. Angiotensin II (Ang II) was delivered using osmotic pumps in Loxl2+/- and WT male and female mice. Blood pressure and pulse wave velocity (PWV) were measured noninvasively to assess hypertension and aortic stiffness. Wire myography and uniaxial tensile testing were used to test aortic vasoreactivity and mechanical properties. Aortic wall composition was examined by histology and Western blotting. The effect of biomechanical strain on LOXL2 expression and secretion by vascular smooth muscle (VSMC) and endothelial cells (EC) was evaluated by uniaxial cyclic stretching of cultured cells. The role of LOXL2 catalytic function on VSMC alignment in response to mechanical loading was determined with LOXL2 inhibition and knockout. Ang II infusion induced hypertension in WT and Loxl2+/- mice of both sexes and increased PWV in WT males but not in Loxl2+/- males, WT females, or Loxl2+/- females. LOXL2 depletion protected males from Ang II mediated potentiation of vasoconstriction but worsened in females and improved aortic mechanical properties in both sexes. Histological analysis showed increased aortic wall thickness in hypertensive WT males but not females and increased intralamellar distance in both sexes, that was ameliorated in Loxl2+/- mice. Western blotting revealed increased collagen I, decreased collagen IV, and increased LOXL2 accumulation and processing in hypertensive mice. Hypertensive cyclic strain contributed to LOXL2 upregulation in the cell-derived matrix in VSMCs but not ECs. LOXL2 catalytic function facilitated VSMC alignment in response to biomechanical strain. In males, arterial stiffening in hypertension is driven both by VSMC response and matrix remodeling. Females exhibit a delayed onset of Ang II-induced hypertension with minimal ECM remodeling but with VSMC dysfunction. LOXL2 depletion ameliorates arterial stiffening and preserves functional contractility and aortic structure in male hypertensive mice. LOXL2 depletion improves aortic mechanics but worsens aortic contractility in hypertensive females. VSMCs are the primary source of LOXL2 in the aorta and hypertension increases LOXL2 processing and shifts to collagen I accumulation. Overall, LOXL2 depletion offers protection in young hypertensive males and females.

Targeting lysyl oxidase like 2 attenuates OVA-induced airway remodeling partly via the AKT signaling pathway

BackgroundAirway epithelium is an important component of airway structure and the initiator of airway remodeling in asthma. The changes of extracellular matrix (ECM), such as collagen deposition and structural disturbance, are typical pathological features of airway remodeling. Thus, identifying key mediators that derived from airway epithelium and capable of modulating ECM may provide valuable insights for targeted therapy of asthma.MethodsThe datasets from Gene Expression Omnibus database were analyzed to screen differentially expressed genes in airway epithelium of asthma. We collected bronchoscopic biopsies and serum samples from asthmatic and healthy subjects to assess lysyl oxidase like 2 (LOXL2) expression. RNA sequencing and various experiments were performed to determine the influences of LOXL2 knockdown in ovalbumin (OVA)-induced mouse models. The roles and mechanisms of LOXL2 in bronchial epithelial cells were explored using LOXL2 small interfering RNA, overexpression plasmid and AKT inhibitor.ResultsBoth bioinformatics analysis and further experiments revealed that LOXL2 is highly expressed in airway epithelium of asthmatics. In vivo, LOXL2 knockdown significantly inhibited OVA-induced ECM deposition and epithelial-mesenchymal transition (EMT) in mice. In vitro, the transfection experiments on 16HBE cells demonstrated that LOXL2 overexpression increases the expression of N-cadherin and fibronectin and reduces the expression of E-cadherin. Conversely, after silencing LOXL2, the expression of E-cadherin is up-regulated. In addition, the remodeling and EMT process that induced by transforming growth factor-β1 could be enhanced and weakened after LOXL2 overexpression and silencing in 16HBE cells. Combining the RNA sequencing of mouse lung tissues and experiments in vitro, LOXL2 was involved in the regulation of AKT signaling pathway. Moreover, the treatment with AKT inhibitor in vitro partially alleviated the consequences associated with LOXL2 overexpression.ConclusionsTaken together, the results demonstrated that epithelial LOXL2 plays a role in asthmatic airway remodeling partly via the AKT signaling pathway and highlighted the potential of LOXL2 as a therapeutic target for airway remodeling in asthma.

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.

#2349 Lysyl oxidase-like 2 inhibitor ameliorates tubulointerstitial fibrosis and albuminuria in cyclosporine induced nephropathy

Abstract Background and Aims Lysyl oxidase-like 2 (LOXL2), an amine oxidase, contributes to fibrotic scarring in the tissue by facilitating collagen cross-linking. Recent data demonstrated upregulation of lysyl oxidase and LOXL2 in the fibrotic kidneys after administration of cylosporine A (CsA). Thus, inhibition of LOXL2 may render therapeutic effects against CsA-induced nephropathy by ameliorating tubulointerstitial fibrosis. Method Low salt fed CD-1 mice were administered saline or CsA (15 mg/kg/day, intraperitoneally) for 8 weeks. At 4 weeks, CsA-treated animals were divided into 2 groups respectively and treated with: (1) vehicle, (2) LOXL2 inhibitor (10 mg/kg/day, gavage feeding) for another 4 weeks up to 8 weeks. We explored the reduction of tubulointerstitial fibrosis as well as albuminuria with administration of LOXL2 inhibitor in CsA nephropathy mouse model. Results CsA administration significantly increased the levels of serum creatinine (10.0 ± 1.2 vs. 28.4 ± 4.3, p = 0.02), tubular injury scores (0.1 ± 0.2 vs. 3.6 ± 1.3, p = 0.03), tubulointerstitial fibrosis (Sirius red positive area, 14 ± 6% vs. 204 ± 43%, p = 0.01), F4/80 positive inflammatory cell infiltration in mouse kidney (2 ± 1 vs. 21 ± 4, p = 0.001). These changes were associated with upregulated mRNA expression of LOXL2, TGF-β1, and monocyte chemoattractant protein-1 (MCP-1). Administration of LOXL2 inhibitor significantly suppressed the expression of alpha-SMA and collagen 1A, intrarenal F4/80 positive inflammatory cell infiltrations (21 ± 4 vs. 14 ± 2, p = 0.001) and improved tubular injury scores (3.6 ± 1.3 vs. 1.6 ± 1.1, p = 0.02). Moreover, LOXL2 inhibitor effectively reduced albuminuria excretion (46 ± 4 vs. 22 ± 6, p = 0.02). Conclusion Our results suggest that LOXL2 inhibitor treatment can attenuate CsA nephropathy progression and LOXL2 may be a potential therapeutic target in CsA nephropathy.

Lysyl oxidase-like 2 as a predictor of hepatocellular carcinoma in patients with hepatitis C virus after sustained virological response

Lysyl oxidase-like 2 (LOXL2) mediates the crosslinking of extracellular collagen, reflecting qualitative changes in liver fibrosis. This study aimed to validate the utility of serum LOXL2 levels as a predictive biomarker for the development of hepatocellular carcinoma (HCC) in patients with hepatitis C virus (HCV) infection who achieved a sustained virological response (SVR). This retrospective study included 137 patients with chronic HCV infection without history of HCC development and who achieved SVR via direct-acting antiviral therapy. Median LOXL2 levels decreased significantly after SVR achievement (pre-Tx, 2.33 ng/mL; post-Tx, 1.31 ng/mL, p < 0.001). Post-Tx LOXL2 levels, fibrosis-4 index, platelet counts, Wisteria floribunda agglutinin-positive human Mac-2 binding protein levels, and alpha-fetoprotein (AFP) levels were identified as independent predictive factors for post-SVR HCC development in the univariate analysis. The incidence of post-SVR HCC development was significantly higher in patients with post-Tx LOXL2 levels ≥ 2.08 ng/mL and AFP levels ≥ 5.0 ng/mL than in patients with elevated levels of either marker or with lower marker levels. Serum LOXL2 levels can serve as a predictive biomarker for HCC development after achieving SVR. The combination of serum LOXL2 and AFP levels provides robust risk stratification for HCC development after SVR, suggesting an enhanced surveillance strategy.

LOXL2 inhibition ameliorates pulmonary artery remodeling in pulmonary hypertension

Background: Conduit pulmonary arterial stiffening and the resultant increase in pulmonary vascular impedance has emerged as an important underlying driver of pulmonary arterial hypertension (PAH). Given that matrix deposition is central to vascular remodeling, we evaluated the role of the collagen crosslinking enzyme lysyl oxidase like 2 (LOXL2) in this study. Methods and Results: Human pulmonary artery smooth muscle cells (PASMCs) subjected to hypoxia showed increased LOXL2 secretion. LOXL2 activity and expression were markedly higher in primary PASMCs isolated from pulmonary arteries of the rat Sugen 5416 + hypoxia (SuHx) model of severe PH. Similarly, LOXL2 protein and mRNA levels were increased in pulmonary arteries (PA) and lungs of rats with PH (SuHx and monocrotaline (MCT) models). Pulmonary arteries (PAs) isolated from rats with PH exhibited hypercontractility to phenylephrine and attenuated vasorelaxation elicited by acetylcholine, indicating severe endothelial dysfunction. Tensile testing revealed a a significant increase in PA stiffness in PH. Treatment with PAT-1251, a novel small-molecule LOXL2 inhibitor, improved active and passive properties of the PA ex vivo. There was an improvement in right heart function as measured by right ventricular pressure volume loops in-vivo with PAT-1251. Importantly PAT-1251 treatment ameliorated PH, resulting in improved pulmonary artery pressures, right ventricular remodeling, and survival. Conclusion: Hypoxia induced LOXL2 activation is a causal mechanism in pulmonary artery stiffening in PH, as well as pulmonary artery mechanical and functional decline. LOXL2 inhibition with PAT-1251 is a promising approach to improve pulmonary artery pressures, right ventricular elastance, cardiac relaxation, and survival in PAH. This work was supported by a NHLBI grant R01HL105296 (to D.E.B.), a NHLBI grant R01HL148112 01 (to L.S.), two Stimulating and Advancing ACCM Research (StAAR) grants from the Department of Anesthesiology and Critical Care Medicine, JHU (to L.S. and J.S.), NHLBI grants R01HL073859 and R01HL126514 (to L.A.S) and a NHLBI K08 grant K08HL145132 (to J.S.). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Loss of phosphatase and tensin homolog (PTEN) increases Lysyl oxidase-like 2 (LOXL2) expression enhancing the growth of fallopian tube epithelial cells as three-dimensional spheroids

BackgroundHigh-grade serous ovarian cancer (HGSOC) accounts for 70–80% of all ovarian cancer-related deaths. Multiple studies have suggested that the fallopian tube epithelium (FTE) serves as the cell of origin of HGSOC. Phosphatase and tensin homolog (PTEN) is a tumor suppressor and its loss is sufficient to induce numerous tumorigenic changes in FTE, including increased migration, formation of multicellular tumor spheroids (MTSs), and ovarian colonization. In murine oviductal epithelial (MOE) cells (the equivalent of human FTE) loss of PTEN results in the upregulation of transcripts associated with the extracellular matrix, with a specific focus on the elevation of lysyl oxidase-like 2 (LOXL2). Although LOXL2 is known to drive transformation and invasion in solid tumors and is associated with a poor prognosis in ovarian cancer, its specific role in the tumorigenesis of ovarian cancer originating from FTE remains unclear. Therefore, we aim to investigate whether LOXL2 mediates tumorigenesis from the fallopian tube epithelium. MethodsIn this study, we utilized clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (CAS9) technology to delete LOXL2 in PTEN-deficient MOE cells to understand its role in mediating the oncogenic effects of PTEN loss. In addition, CRISPR-CAS9 was used to delete LOXL2 in OVCAR8 ovarian cancer cells. We monitored the changes in tumorigenic properties, such as migration, invasion, and growth of three-dimensional (3D) spheroids, to assess whether the loss of LOXL2 resulted in any changes. ResultsWe found that a reduction in LOXL2 expression did not significantly change the migration or invasive capabilities of PTEN-depleted MOE or human ovarian cancer cells. However, we found that a reduction in LOXL2 expression resulted in a significant reduction in 3D MTS formation and survival in both lines. ConclusionsThese results reveal for the first time that PTEN loss in FTE cells increases LOXL2 expression through downregulation of Pax2, and LOXL2 deletion blocks 3D spheroid formation.

LOXL2 in non‐alcoholic Steatohepatitis (NASH): Insights into fibrosis pathogenesis and therapeutic potential

AbstractLiver fibrosis involves increased extracellular matrix (ECM) deposition, with lysyl oxidase‐like 2 (LOXL2) emerging as a key player due to its upregulation in fibrotic tissue. As a member of the lysyl oxidase protein family, LOXL2 contributes to ECM accumulation and remodelling through fibre cross‐linking. Its aberrant expression in non‐alcoholic steatohepatitis (NASH) implicates it in liver fibrosis. LOXL2 promotes fibrosis by activating hepatic stellate cells, cross‐linking ECM proteins, and influencing oxidative stress, inflammation and lipid metabolism. Preclinical studies on LOXL2 inhibitors show promise in reducing fibrosis and improving liver function. Ongoing clinical trials further highlight LOXL2 as a potential anti‐fibrotic target. However, challenges such as species differences, tissue‐specific effects and the complexity of NASH pathogenesis require additional research. Understanding LOXL2's role in NASH will aid in developing effective treatments for NASH‐related fibrosis and liver damage.

RNA-binding protein RPS7 promotes hepatocellular carcinoma progression via LOXL2-dependent activation of ITGB1/FAK/SRC signaling

BackgroundMetastasis is one of the leading cause contributes to treatment failure and poor prognosis of hepatocellular carcinoma (HCC) patients. The underlying mechanism of HCC metastasis remains to be determined. Although several RNA binding proteins (RBPs) have been found to participate in tumorigenesis and progression of liver cancer, the role of RBPs in HCC patients with extrahepatic metastases is poorly understood.MethodsBy performing RNA-seq of primary HCC tissues (including HCC with extrahepatic metastasis and those did not develop metastasis), we identified a set of HCC metastasis-associated RBPs candidates. Among which, ribosomal protein S7 (RPS7) was found to be remarkably increased in HCC tissues and be strongly related to HCC poor survival. Overexpression or CRISPR-Cas9–mediated knockout were applied to investigate the role of RPS7 on the metastasis-associated phenotypes of HCC cells. RNA sequencing, RIP, RNA-pull down, dual luciferase reporter assay, nascent RNA capture assay, and RNA decay and so on, were applied to reveal the underlying mechanism of RPS7 induced HCC metastasis.ResultsGain- and loss- of function analyses revealed that RPS7 promoted HCC cells adhesion, migration and invasion capabilities, as well as lung metastasis. Mechanistically, we uncovered that lysyl oxidase-like 2 (LOXL2) was a critical downstream target of RPS7. RPS7 could stabilize LOXL2 mRNA by binding to AUUUA motifs in the 3155–3375 region of the 3’UTR of LOXL2 mRNA, thus increased LOXL2 expression via elevating LOXL2 mRNA abundance. Further research revealed that LOXL2 could accelerate focal adhesion formation through maintaining the protein stability of ITGB1 and activating ITGB1-mediated FAK/SRC signaling pathway, and thereby contribute to the pro-metastasis effect of RPS7.ConclusionsTaken together, our data reveal a novel function of RPS7 in HCC metastasis, also reveal the critical roles of the RPS7/LOXL2/ITGB1 axis in HCC metastasis and shed new light on the exploration of molecular drugs against HCC.

Neural Wiskott-Aldrich syndrome protein (N-WASP) promotes distant metastasis in pancreatic ductal adenocarcinoma via activation of LOXL2.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive solid malignancies. A specific mechanism of its metastasis has not been established. In this study, we investigated whether Neural Wiskott-Aldrich syndrome protein (N-WASP) plays a role in distant metastasis of PDAC. We found that N-WASP is markedly expressed in clinical patients with PDAC. Clinical analysis showed a notably more distant metastatic pattern in the N-WASP-high group compared to the N-WASP-low group. N-WASP was noted to be a novel mediator of epithelial-mesenchymal transition (EMT) via gene expression profile studies. Knockdown of N-WASP in pancreatic cancer cells significantly inhibited cell invasion, migration, and EMT. We also observed positive association of lysyl oxidase-like 2 (LOXL2) and focal adhesion kinase (FAK) with the N-WASP-mediated response, wherein EMT and invadopodia function were modulated. Both N-WASP and LOXL2 depletion significantly reduced the incidence of liver and lung metastatic lesions in orthotopic mouse models of pancreatic cancer. These results elucidate a novel role for N-WASP signaling associated with LOXL2 in EMT and invadopodia function, with respect to regulation of intercellular communication in tumor cells for promoting pancreatic cancer metastasis. These findings may aid in the development of therapeutic strategies against pancreatic cancer.

A protein complex of LCN2, LOXL2 and MMP9 facilitates tumor metastasis in esophageal cancer.

During malignant tumor development, the extracellular matrix (ECM) is usually abnormally regulated. Dysregulated expression of lysyl oxidase-like 2 (LOXL2), matrix metalloproteinase 9 (MMP9) and lipocalin 2 (LCN2) are associated with ECM remodeling. In this study, protein-protein interaction assays indicated that LCN2 and LOXL2 interactions and LCN2 and MMP9 interactions occurred both intracellularly and extracellularly, but interactions between LOXL2 and MMP9 only occurred intracellularly. The LCN2/LOXL2/MMP9 ternary complex promoted migration and invasion of esophageal squamous cell carcinoma (ESCC) cells, as well as tumor growth and malignant progression in vivo, while the iron chelator deferoxamine mesylate (DFOM) inhibited ESCC tumor growth. Co-overexpression of LCN2, LOXL2 and MMP9 enhanced the ability of tumor cells to degrade fibronectin and Matrigel, increased the formation and extension of filopodia, and promoted the rearrangement of microfilaments through upregulation of profilin 1. In addition, the LCN2/LOXL2/MMP9 ternary complex promoted the expression of testican-1 (SPOCK1), and abnormally activated the FAK/AKT/GSK3β signaling pathway. In summary, the LCN2/LOXL2/MMP9 ternary complex promoted the migration and invasion of cancer cells and malignant tumor progression through multiple mechanisms, and could be a potential therapeutic target.

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.