4015

LOX

lysyl oxidase;LOX;lysyl oxidase

protein-lysine 6-oxidase

5q23.2

protein-coding

OBJECTIVE: To investigate possible mechanism of silencing lysyl oxidase (LOX) gene by RNA interference affecting on invasion and metastasis of breast cancer cells. METHODS: LOX-RNAi-LV was designed and synthesized, which was transfected into breast cancer cell line MDA-MB-231. The expressions of LOX, MMP-2 and MMP-9 were determined by Real-time PCR in MDA-MB-231 cells, and the protein expression of LOX was determined by Western blot. The cells migration and invasion abilities were measured by cell migration and invasion test. 111 cases of breast cancer tissue and cancer-adjacent breast tissues and 20 cases of benign lesion tissues of LOX, MMP-2 and MMP-9 were detected by immunohistochemistry, and the relationship of LOX and clinicopathological characteristics was analyzed. RESULTS: The expression levels of LOX mRNA and protein were down-regulated obviously after transfecting LOX-RNAi-LV, with the inhibition rate 89.2% +/- 1.3% and 84.4% +/- 0.4% respectively. The relative expressions of MMP-2 and MMP-9 mRNA were 0.496 +/- 0.021 and 0.571 +/- 0.099 in RNAi group, which was significantly lower than that in negative control group (0.846 +/- 0.047, 0.786 +/- 0.042) and blank control group (1.000 +/- 0.000, 1.000 +/- 0.000) (both P < 0.05). Cell migration and invasion test showed the average cell numbers per field in the group RNAi were 47 +/- 2 and 63 +/- 2, was significantly lower than that in negative control group (100 +/- 1, 118 +/- 2) and blank control group (100 +/- 1, 118 +/- 2) (both P < 0.05). The expression of LOX protein in breast cancer, cancer-adjacent breast tissues and benign breast tumor were 48.6% (54/111), 26.1% (29/111), 20.0% (4/20), the expression of LOX protein in breast cancer was significantly higher than that in cancer-adjacent breast tissues and benign lesion tissues (P = 0.019). The expression of LOX protein was associated with clinical stage, lymph node metastasis, tumor size. Correlation analysis showed that LOX protein expression was significantly positive correlation with MMP-2 (r = 0.262, P = 0.005) and MMP-9 (r = 0.424, P = 0.000). CONCLUSION: LOX can promote invasion and metastasis of breast cancer; LOX and MMP-2, MMP-9 may have a synergistic role in promoting invasion and metastasis of breast cancer.

Elucidating targets of physiological tumor metastasis suppressors can highlight key signaling pathways leading to invasion and metastasis. To identify downstream targets of the metastasis suppressor Raf-1 kinase inhibitory protein (RKIP/PEBP1), we utilized an integrated approach based upon statistical analysis of tumor gene expression data combined with experimental validation. Previous studies from our laboratory identified the architectural transcription factor and oncogene, high mobility group AT-hook 2 (HMGA2), as a target of inhibition by RKIP. Here we identify two signaling pathways that promote HMGA2-driven metastasis. Using both human breast tumor cells and an MMTV-Wnt mouse breast tumor model, we show that RKIP induces and HMGA2 inhibits expression of miR-200b; miR-200b directly inhibits expression of lysyl oxidase (LOX), leading to decreased invasion. RKIP also inhibits syndecan-2 (SDC2), which is aberrantly expressed in breast cancer, via downregulation of HMGA2; but this mechanism is independent of miR-200. Depletion of SDC2 induces apoptosis and suppresses breast tumor growth and metastasis in mouse xenografts. RKIP, LOX and SDC2 are coordinately regulated and collectively encompass a prognostic signature for metastasis-free survival in ER-negative breast cancer patients. Taken together, our findings reveal two novel signaling pathways targeted by the metastasis suppressor RKIP that regulate remodeling of the extracellular matrix and tumor survival.

Lysyl oxidase (LOX) is an amine oxidase that catalyzes the cross-linking of collage or elastin in the extracellular matrix, regulating the tensile strength and structural integrity of connective tissues. Recently, four paralogues (LOXL, LOXL2, LOXL3 and LOXL4) of LOX have been identified in humans, each containing the functional domains required for the amine oxidase activity toward collagen and elastin. Paradoxical roles of the LOX family members have been reported in various neoplastic tissues as tumor suppressors or promoters depending on tumor status and type. To address expression of the LOX family genes in colorectal adenocarcinomas, we performed real-time PCR analysis with matched tumor/normal tissue specimens from 104 patients. The expression of the LOX family genes was not statistically associated with tumor location, stage, growth type, or differentiation status. However, upregulation of LOX, LOXL2 and LOXL4 was significantly correlated with absence of lymphovascular invasion (P=0.012, 0.014 and 0.005, respectively), suggesting that the oxygen tension in or around the tumors may be an important regulator for the differential expression of LOX, LOXL2 and LOXL4 in colorectal cancer. Additionally, expression of LOX, but not the other LOX family genes, was significantly upregulated in patients with a diffuse cytoplasmic expression pattern of CEA, indicating that LOX upregulation may be associated with increased invasiveness and metastatic potential in colorectal cancer.

BACKGROUND: Emerging evidence implicates lysyl oxidase (LOX), an extracellular matrix-modifying enzyme, in promoting metastasis of solid tumors. We investigated whether LOX plays an important role in the metastasis of colorectal cancer (CRC). METHODS: We analyzed LOX expression in a patient CRC tissue microarray consisting of normal colon mucosa (n = 49), primary (n = 510), and metastatic (n = 198) tissues. LOX was overexpressed in CRC cell line SW480 (SW480+LOX), and the expression was knocked down in CRC cell line SW620 using LOX-specific short hairpin RNA (SW620+shLOX). Effect of LOX manipulation on three-dimensional cell proliferation and invasion was characterized in vitro. Effect of LOX manipulation on tumor proliferation and metastasis was investigated in a subcutaneous tumor mouse model (n = 3 mice per group) and in an intrasplenic metastatic mouse model (n = 3 mice per group). The mechanism of LOX-mediated effects via v-src sarcoma (Schmidt-Ruppin A-2) viral oncogene homolog (avian) (SRC) was investigated using dasatinib, an inhibitor of SRC activation. All statistical tests were two-sided. RESULTS: Compared with normal colon tissue (n = 49), LOX expression was statistically significantly increased in tumor tissues (n = 510) of CRC patients (P < .001), and a greater increase was observed in metastatic tissue (n = 198). SW480+LOX cells showed a statistically significantly increased three-dimensional proliferation (P = .037) and invasion (P = .015), whereas SW620+shLOX cells showed reduced proliferation (P = .011) and invasion (P = .013) compared with controls. Subcutaneous tumor growth in mice was statistically significantly increased in SW480+LOX tumors (P = .036) and decreased in SW620+shLOX tumors (P = .048), and metastasis was statistically significantly increased in SW480+LOX tumors (P = .044) and decreased in SW620+shLOX tumors (SW620 control vs SW620+shLOX, mean = 1.0 luminescent signal, 95% confidence interval = 0.3 to 1.7 luminescent signal, vs mean = 0.3 luminescent signal, 95% confidence interval = 0.1 to 0.5 luminescent signal; P = .035) compared with controls. LOX-mediated effects on tumor progression were associated with SRC activation, and these effects were inhibited by dasatinib. CONCLUSIONS: LOX showed an important role in CRC cell proliferation and metastasis and was dependent on the activation of SRC. These results have the potential to identify patients with high SRC activity, who may benefit from dasatinib treatment.

BACKGROUND: Lysyl oxidase (LOX), an extracellular matrix-remodeling enzyme, has been reported to regulate tumor metastasis. We investigated the clinical significance of LOX expression in esophageal squamous cell carcinoma (ESCC). METHODS: We examined LOX expression in ESCC cell lines by real-time reverse-transcriptase polymerase chain reaction (RT-PCR) and Western blotting. We also examined LOX expression by real-time RT-PCR in 39 surgically resected ESCC and by immunohistochemistry in 122 surgically resected ESCC. RESULTS: LOX messenger RNA (mRNA) was expressed at a high level in TTn (originating from an ESCC metastatic lesion); at a moderate level in TE-2 and TE-15; and at a low level in TE-1, TE-8, and TE-13. In Western blotting, all cell lines expressed the catalytically inactive 50-kDa LOX at approximately the same levels, but catalytically active 32-kDa LOX was overexpressed only in TTn. LOX mRNA levels in ESCC tissues were significantly higher than those observed in normal esophageal tissues (P < 0.001) and had no significant correlation with tumor-node-metastasis (TNM) factors. High LOX protein expression had a significant correlation with presence of lymph node metastasis (P = 0.009) and number of lymph node metastases (P = 0.047). Overall and cancer-specific survival rates of patients with ESCC with high LOX expression were significantly lower than those of patients with ESCC with low LOX expression (P = 0.024 and P = 0.012). Univariate and multivariate analyses revealed that high LOX protein expression was an independent prognostic factor for ESCC. CONCLUSIONS: Our findings suggest that LOX can serve as a predictive marker of lymph node metastasis and prognosis in ESCC.

BACKGROUND & OBJECTIVE: Lysyl oxidase(LO), one of newly discovered candidate of tumor suppressor genes, was reported that its expression was closely associated with recurrence and metastasis of breast and prostate carcinomas. However, till now there was no report evaluating the relationship between this gene expression and relapse or metastasis of upper digestive tract carcinomas. This study was designed to explore the relationship between the expression of LO gene and recurrence as well as metastasis of malignant upper digestive tract tumors such as esophageal, cardiac, and gastric cancers. METHOD: LO expression in esophageal, cardiac, and gastric cancer was determined by reverse transcriptase polymerase chain reaction (RT-PCR). RESULTS: RT-PCR amplification demonstrated that the expression rate was 42.1% (16/38), 42.9% 9(9/21), and 28.0% (7/25) in esophageal, cardiac, and gastric cancers, respectively. Furthermore, the expression rate of LO mRNA was lower in the tumor tissues with lymph nodes metastasis. And this was also observed in tumor with deep muscular layer infiltration(P < 0.05). In contrast, the reduced expression of the LO gene had no relation to histological classification, invasion pattern, tumor size, and number of metastasis lymph nodes(P > 0.05). CONCLUSIONS: These findings suggest that LO gene may play an important role in metastasis of esophageal, cardiac, and gastric carcinomas.

OBJECTIVE: To compare the expressions of lysyl oxidase (LOX) and matrix metalloproteinases-2 (MMP-2) in gastric cancer and pericancerous tissues, in gastric cancers with and without lymph node metastasis, and to analyze the effects of LOX and MMP-2 on tumor invasion and metastasis. METHODS: Gastric cancer and pericancerous tissues were collected from 46 patients who underwent surgery. Levels of LOX and MMP-2 mRNA were detected by RT-PCR. Protein abundance of LOX and MMP-2 was examined using Western blot. RESULTS: expressions of LOX and MMP-2 mRNA, and protein in 46 gastric cancers were significantly higher than that in 46 pericancerous tissues. In gastric cancer with lymph node metastasis, the levels of LOX and MMP-2 mRNA and protein were higher than those in gastric cancers without lymph node metastasis (P < 0.05). In the groups of gastric cancer with lymph node metastasis, expression of LOX was positively correlated with MMP-2 protein expression (P < 0.01). CONCLUSIONS: expressions of LOX and MMP-2 in gastric cancer tissues are significantly higher than that in pericancerous tissues. The expressions of LOX and MMP-2 in gastric cancer with lymph node metastasis are higher than that in gastric cancer without lymph node metastasis. expressions of LOX and MMP-2 are positively correlated. The results suggest that LOX and MMP-2 may promote the growth and metastasis of gastric cancer.

The purpose of this study was to determine whether lysyl oxidase (LOX) is a useful marker of metastasis in gastric cancer (GC) patients in combination with tumor markers carcino-embryonic antigen (CEA), carbohydrate antigen 724 (CA724), carbohydrate antigen 19-9 (CA19-9), and carbohydrate antigen 125 (CA125). There were 215 GC patients (67 without metastasis, 102 with lymph node metastasis, and 46 with peritoneal metastasis) who presented to the Affiliated cancer Hospital of Guangxi Medical University between May 2009 and November 2012 that were enrolled in this study. The LOX expression level and the serum concentration of the four tumor markers were evaluated preoperatively. All patients underwent computed tomography (CT) and ultrasonography (US) before surgery. Statistical analysis, including receiver operating characteristic (ROC) curve analysis, area under the curve (AUC) analysis, and logistic regression analysis, was performed to evaluate the diagnostic value of these markers in predicting metastasis in GC. For predicting lymph node metastasis in GC, the sensitivity of LOX, CEA, CA724, CA199, and CA125 was 44.12, 12.75, 21.57, 23.53, and 15.69 %, respectively, and increased to 79.41 % in combination. For predicting peritoneal metastasis in GC, the sensitivity of these markers was 56.52, 23.91, 34.78, 36.96, and 34.78 %, respectively, and increased to 91.30 % in combination. Combining LOX with CEA, CA724, CA199, and CA125 could increase the sensitivity of predicting lymph nodes metastasis and peritoneal metastasis in GC. Surgeons can use these markers to determine the best treatment options for patients. Additional large-scale, prospective, multicenter studies are urgently needed to further confirm the results of this study.

PURPOSE: To validate lysyl oxidase (LOX), a hypoxia-related protein, as a marker for metastasis in an independent head and neck cancer (HNC) patient group enrolled onto a prospective trial. PATIENTS AND METHODS: We performed traditional immunohistochemical (IHC) staining and automated quantitative analysis (AQUA) for LOX expression in 66 HNC patients from one institution. We also performed AQUA staining for LOX in 306 of 1,113 patients treated on a phase III trial comparing four radiation fractionation schedules in locally advanced HNC (RTOG 90-03). Pretreatment characteristics and outcome were similar between patients with and without LOX assessment. We correlated AQUA LOX expression with time to metastasis (TTM), time to progression (TTP), and overall survival (OS). RESULTS: LOX expression from both staining methods predicted for TTM in the first 66 patients. Multivariate analysis, controlling for significant parameters including nodal stage and performance status, revealed tumor LOX expression, as a continuous variable, was an independent predictor for TTM (hazard ratio [HR], 1.21; 95% CI, 1.10 to 1.33; P = .0001), TTP (HR, 1.06; 95% CI, 1.02 to 1.10; P = .0069), and OS (HR, 1.04; 95% CI, 1.00 to 1.07; P = .0311) in RTOG 90-03 patients. This translates into a 259% increase in metastatic risk for a patient at the 75th percentile of LOX compared with one at the 25th percentile. CONCLUSION: AQUA LOX expression was strongly associated with increased metastasis, progression, and death in RTOG 90-03 patients. This study validates that LOX is a marker for metastasis and survival in HNC.

metastasis is a multistep process responsible for most cancer deaths, and it can be influenced by both the immediate microenvironment (cell-cell or cell-matrix interactions) and the extended tumour microenvironment (for example vascularization). Hypoxia (low oxygen) is clinically associated with metastasis and poor patient outcome, although the underlying processes remain unclear. Microarray studies have shown the expression of lysyl oxidase (LOX) to be elevated in hypoxic human tumour cells. Paradoxically, LOX expression is associated with both tumour suppression and tumour progression, and its role in tumorigenesis seems dependent on cellular location, cell type and transformation status. Here we show that LOX expression is regulated by hypoxia-inducible factor (HIF) and is associated with hypoxia in human breast and head and neck tumours. Patients with high LOX-expressing tumours have poor distant metastasis-free and overall survivals. Inhibition of LOX eliminates metastasis in mice with orthotopically grown breast cancer tumours. Mechanistically, secreted LOX is responsible for the invasive properties of hypoxic human cancer cells through focal adhesion kinase activity and cell to matrix adhesion. Furthermore, LOX may be required to create a niche permissive for metastatic growth. Our findings indicate that LOX is essential for hypoxia-induced metastasis and is a good therapeutic target for preventing and treating metastases.

tumor cell metastasis is facilitated by "premetastatic niches" formed in destination organs by invading bone marrow-derived cells (BMDCs). Lysyl oxidase (LOX) is critical for premetastatic niche formation. LOX secreted by hypoxic breast tumor cells accumulates at premetastatic sites, crosslinks collagen IV in the basement membrane, and is essential for CD11b+ myeloid cell recruitment. CD11b+ cells adhere to crosslinked collagen IV and produce matrix metalloproteinase-2, which cleaves collagen, enhancing the invasion and recruitment of BMDCs and metastasizing tumor cells. LOX inhibition prevents CD11b+ cell recruitment and metastatic growth. CD11b+ cells and LOX also colocalize in biopsies of human metastases. Our findings demonstrate a critical role for LOX in premetastatic niche formation and support targeting LOX for the treatment and prevention of metastatic disease.