Overexpression of LAPTM4B-35 is associated with poor prognosis in colorectal carcinoma

Regulation of Phosphoinositide Signaling by Scaffolds at Cytoplasmic Membranes

Cytoplasmic phosphoinositides (PI) are critical regulators of the membrane-cytosol interface that control a myriad of cellular functions despite their low abundance among phospholipids. The metabolic cycle that generates different PI species is crucial to their regulatory role, controlling membrane dynamics, vesicular trafficking, signal transduction, and other key cellular events. The synthesis of phosphatidylinositol (3,4,5)-triphosphate (PI3,4,5P3) in the cytoplamic PI3K/Akt pathway is central to the life and death of a cell. This review will focus on the emerging evidence that scaffold proteins regulate the PI3K/Akt pathway in distinct membrane structures in response to diverse stimuli, challenging the belief that the plasma membrane is the predominant site for PI3k/Akt signaling. In addition, we will discuss how PIs regulate the recruitment of specific scaffolding complexes to membrane structures to coordinate vesicle formation, fusion, and reformation during autophagy as well as a novel lysosome repair pathway.

Overexpression of LAPTM4B-35 is a negative prognostic factor in head and neck squamous cell carcinoma

Overexpression of LAPTM4B-35 (lysosomal-associated transmembrane protein 4β-35) is associated with a poor prognosis in numerous malignant tumours. Expression patterns and effects of LAPTM4B-35 on head and neck squamous cell carcinomas (HNSCC) are unknown. The aim of this study was to investigate the prognostic relevance of LAPTM4B-35 in HNSCC. Tissue microarrays were constructed with primary tumours and associated lymph node metastases isolated from 127 patients. The expression of LAPTM4B-35 was investigated by immunohistochemistry and the results were correlated with survival data. LAPTM4B-35 in the primary tumour was highly expressed in 47.2% of the patients (60/127). LAPTM4B-35 expression was significantly associated with tumour stage. Moreover, overexpression of LAPTM4B-35 correlated with a significantly worse disease-free survival (10.23 years vs. not reached) and a higher recurrence rate (40.7% vs. 25%). High expression of LAPTM4B-35 in lymph node metastasis was found in 29.2% of cases. In 19.4% of cases, high LAPTM4B-35 expression was observed in both the primary tumour and corresponding lymph node metastases. In conclusion, our data indicates that overexpression of LAPTM4B-35 is associated with poor prognosis and may therefore serve as a new prognostic marker in HNSCC.

LAPTM4B-35 expression is associated with pathological grades and clinical stages in salivary adenoid cystic carcinoma

Salivary adenoid cystic carcinoma is one of the most common malignancies of the head and neck. The lysosome-associated protein transmembrane-4β gene (LAPTM4B) is a novel oncogene that has been found overexpressed in a number of clinically aggressive cancers. This study aimed to investigate the expression of the LAPTM4B-35 protein in normal salivary gland and salivary adenoid cystic carcinoma, a relatively indolent malignancy, and explore its clinicopathological significance in this malignancy. By immunohistochemical analysis, LAPTM4B-35 expression was evaluated in 106 cancer tissues, their adjacent non-cancerous tissues and five normal salivary glands. The correlation of LAPTM4B-35 expression with clinicopathological parameters was assessed using Chi-square or Fisher's exact test. The level of LAPTM4B-35 expression varied among different cell types of normal salivary glands. It was expressed at a fairly low level in serous and mucous acini, at low level in intercalated duct and excretory duct cells and moderately in secretory/striated ducts. In 50% of high grade tumor tissues tested, LAPTM4B-35 was markedly overexpressed. LAPTM4B-35 levels were significantly associated with histological grade and clinical stage. LAPTM4B-35 plays an important role in salivary adenoid cystic carcinoma and may serve as a diagnostic marker and a target for individualized therapy.

In Vitro and In Vivo Study on the Effect of Lysosome-associated Protein Transmembrane 4 Beta on the Progression of Breast Cancer

Purpose

Although the effect of lysosome-associated protein transmembrane 4 beta (LAPTM4B) on the proliferation, migration, and invasion of breast cancer (BC) cells has already been studied, its specific role in BC progression is still elusive. Here, we evaluated the effect of different levels of LAPTM4B expression on the proliferation, invasion, adhesion, and tumor formation abilities of BC cells in vitro, as well as on breast tumor progression in vivo.

Methods

We investigated the influence of LAPTM4B expression on MCF-7 cell proliferation, invasion, adhesion, and tube formation abilities in vitro through its overexpression or knockdown and on breast tumor progression in vivo.

Results

Cell growth curves and colony formation assays showed that LAPTM4B promoted the proliferation of breast tumor cells. Cell cycle analysis results revealed that LAPTM4B promoted the entry of cells from the G1 into the S phase. Transwell invasion and cell extracellular matrix adhesion assays showed that LAPTM4B overexpression increased the invasion and adhesion capabilities of MCF-7 cells. More branches were observed in MCF-7 cells overexpressing LAPTM4B under an electron microscope. In comparison with LAPTM4B overexpression, LAPTM4B knockdown decreased the expression of vascular endothelial growth factor-A and significantly inhibited the vasculogenic tube formation ability of tumors. These results were also verified with western blot analysis.

Conclusion

LAPTM4B promoted the proliferation of MCF-7 cells through the downregulation of p21 (WAF1/CIP1) and caspase-3, and induced cell invasion, adhesion, and angiogenesis through the upregulation of hypoxia-inducible factor 1 alpha, matrix metalloproteinase 2 (MMP2), and MMP9 expression. This specific role deems LAPTM4B as a potential therapeutic target for BC treatment.

MicroRNA-132-3p inhibits tumor malignant progression by regulating lysosomal-associated protein transmembrane 4 beta in breast cancer

Lysosomal‐associated protein transmembrane 4 beta (LAPTM4B), a proto‐oncogene, has been shown to be a positive modulator in cancer progression. However, the mechanism of LAPTM4B regulation is not fully elucidated. Aberrant microRNAs (miRNAs) can regulate gene expression by interfering with target transcripts and/or translation to exert tumor‐suppressive or oncogenic effects in breast cancer. In the present study, miR‐132‐3p, which was predicted by relevant software, was confirmed to directly bind to the 3′ untranslated region (3′UTR) of LAPTM4B and negatively regulate its expression in luciferase reporter and western blot assays. Subsequently, we validated that miR‐132‐3p was downregulated in breast cancer tissues. Receiver‐operating characteristic curve analysis indicated that miR‐132‐3p had accurate diagnostic value, and a Kaplan‐Meier and Cox regression model showed that miR‐132‐3p was a potential prognostic marker for recurrence, showing low levels in breast cancer patients. In addition, we showed that miR‐132‐3p was inversely correlated with LAPTM4B expression in the above samples. Functionally, miR‐132‐3p suppressed the migration and invasion of breast carcinoma cells through LAPTM4B by mediating epithelial‐mesenchymal transition signals, and partially reversed the carcinogenic effects of LAPTM4B by inhibiting the PI3K‐AKT‐mTOR signaling pathway. Taken together, these findings provide the first comprehensive analysis of miR‐132‐3p as a direct LAPTM4B‐targeted miRNA, and shed light on miR‐132‐3p/LAPTM4B as a significant functional axis involved in the oncogenesis and metastasis of breast cancer.

Clinical impact of circulating LAPTM4B-35 in pancreatic ductal adenocarcinoma

PURPOSE

LAPTM4B is upregulated in a wide range of cancers associated with poor prognosis. However, the clinical impact of LAPTM4B as diagnostic and prognostic marker in pancreatic ductal adenocarcinoma (PDAC) remains unknown. Thus, the aim of the present study was to investigate the expression of LAPTM4B as circulating marker in PDAC.

METHODS

Expression analysis of LAPTM4B-35 in pancreatic tissue and preoperative blood serum samples of 169 patients with PDAC UICC Stages I-IV (n = 98), chronic pancreatitis (n = 41), and healthy controls (n = 30) by immunohistochemistry, Western blot, and ELISA. Descriptive and explorative statistical analyses of LAPTM4B-35's potential as diagnostic and prognostic marker in PDAC.

RESULTS

Expression of LAPTM4B-35 was significantly increased in tumor tissue and corresponding blood serum samples of patients with PDAC (each p < 0.001) and it could well discriminate PDAC from healthy controls and chronic pancreatitis (p < 0.001; p = 0.0037). LAPTM4B-35 in combination with CA.19-9 outperforms the diagnostic accuracy with an AUC of 0.903 (p < 0.001), sensitivity of 82%, and specificity of 92%. Kaplan-Meier survival analysis revealed an improved overall survival in PDAC UICC I-IV with low expression of circulating LAPTM4B-35 (17 versus 10 months, p = 0.039) as well as an improved relapse-free survival in curatively treated PDAC UICC I-III (16 versus 10 months; p = 0.037). Multivariate overall and recurrence-free survival analyses identified LAPTM4B-35 as favorable prognostic factor in PDAC patients (HR 2.73, p = 0.021; HR 3.29, p = 0.003).

CONCLUSION

LAPTM4B-35 is significantly deregulated in PDAC with high diagnostic and prognostic impact as circulating tumor marker.

Co-expression of HIF-1α, MDR1 and LAPTM4B in peripheral blood of solid tumors

The hypoxic tumor microenvironment is the major contributor of chemotherapy resistance in solid tumors. One of the key regulators of hypoxic responses within the cell is the hypoxia inducible factor-1α (HIF-1α) that is involved in transcription of genes promoting cell survival and chemotherapy resistance. Multidrug resistance gene-1 (MDR1) and Lysosome-associated protein transmembrane 4B-35 (LAPTM4B-35) are among those notable players which augment their responses to cellular hypoxia. MDR1 is the hypoxia responsive gene involved in multidrug resistance phenotype while LAPTM4B-35 is involved in chemotherapy resistance by stabilizing HIF-1α and overexpressing MDR1. Overexpression of HIF-1α, MDR1 and LAPTM4B has been associated with poor disease outcome in many cancers when studied individually at tissue level. However, accessibility of the tissues following the course of chemotherapy for ascertaining chemotherapy resistance is difficult and sometimes not clinically feasible. Therefore, indication of hypoxic biomarkers in patient’s blood can significantly alter the clinical outcome. Hence there is a need to identify a blood based marker to understand the disease progression. In the current study the expression of hypoxia associated chemotherapy resistance genes were studied in the peripheral blood lymphocytes of solid tumor patients and any potential correlation with disease progression were explored. The expression of HIF-1α, MDR1 and LAPTM4B was studied in blood of 72 breast, 42 ovarian, 32 colon and 21 prostate cancer patients through real time PCR analysis using delta cycle threshold method. The statistical scrutiny was executed through Fisher’s Exact test and the Spearman correlation method. There was 12–13 fold increased in expression of HIF-1α, two fold increased in MDR1 and 13–14 fold increased in LAPTM4B mRNA level in peripheral blood of breast, ovarian, prostate and colon cancer patients. In the current study there was an association of HIF-1α, MDR1 and LAPTM4B expression with advanced tumor stage, metastasis and chemotherapy treated group in breast, ovarian, prostate and colon cancer patients. The Spearman analysis also revealed a positive linear association among HIF-1α, MDR1 and LAPTM4B in all the studied cancer patients. The elevated expression of HIF-1α, MDR1 and LAPTM4B in peripheral blood of solid tumor patients can be a predictor of metastasis, disease progression and treatment response in these cancers. However, larger studies are needed to further strengthen their role as a potential biomarker for cancer prognosis.

Prognostic Values of LAPTM4B-35 in Human Cancer: A Meta-analysis

Background: Lysosome-associated protein transmembrane-4β-35(LAPTM4B-35) has been observed overexpressed in multiple malignant tumors. However, the prognostic value of LAPTM4B-35 remains controversial. Therefore, we conducted a meta-analysis to evaluate the prognostic value of LAPTM4B-35 in human cancers. Methods: The relevant publications were obtained by systematically searching the PubMed, Web of Science, Embase, Wanfang, and China National Knowledge Infrastructure (CNKI) databases. Pooled hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated for the prognosis value of LAPTM4B-35 for cancer patient. Results: Our result suggest that LAPTM4B-35 overexpression is significantly associated with poor overall survival (OS) (HR = 2.49, 95% CI = 1.87-3.32, p < 0.001), disease-free survival (DFS) (HR = 2.43, 95% CI = 1.35-4.35, p = 0.003), and progression-free survival (PFS) (HR = 4.12, 95% CI = 2.30-7.37, p < 0.001). Moreover, subgroup analysis revealed significant association with poor OS in lung (HR = 2.05, 95% CI = 1.37-3.06, p < 0.001), gastric carcinoma (HR = 1.88, 95% CI = 1.01-3.50, p < 0.047) and ovarian cancer (HR = 4.94, 95% CI = 1.44-16.94, p = 0.011). Conclusion: LAPTM4B-35 may be a novel predictive biomarker and a potential target for treatment.

Detection of urinary survivin using a magnetic particles-based chemiluminescence immunoassay for the preliminary diagnosis of bladder cancer and renal cell carcinoma combined with LAPTM4B

The aim of the present study was to establish a simple step magnetic particles (MPs) based chemiluminescence enzyme immunoassay (CLEIA) for the detection of urinary survivin, and to investigate the diagnostic value of urinary survivin and lysosome-associated protein transmembrane-4β (LAPTM4B) in bladder cancer (BC) and renal cell carcinoma (RCC). The MPs-based CLEIA was developed on the basis of a double antibodies sandwich immunoreaction and luminol-H₂O₂ chemiluminescence system. The parameters of the method were optimized and evaluated. Urine samples were obtained from 200 BC patients, 81 RCC patients and 114 healthy individuals, and the MPs-based CLEIA method was employed to detect their urinary survivin. At the same time, the urinary LAPTM4B levels of the BC patients, RCC patients and the healthy controls were measured. The diagnostic efficiency of urinary survivin and LAPTM4B in BC and RCC was evaluated separately and jointly. A one-step MPs-based CLEIA for the detection of urinary survivin with good accuracy and precision was established. The signals were dependent on survivin concentrations in the range, 0 to 200 ng/ml, and the detection limit was 0.949 ng/ml. The areas under the receiver operating characteristic curves (AUC) were 0.771 in BC and 0.763 in RCC for urinary survivin. Urinary survivin was correlated with the tumor stage (P=0.002), lymph node metastasis (P=0.017), distant metastasis (P=0.005) and tumor size (P=0.02) of BC; however, no association with the clinicopathological parameters in RCC was observed. The AUCs for urinary LAPTM4B were 0.738 in BC and 0.704 in RCC, respectively. The AUCs for them combined were 0.842 in BC and 0.920 in RCC. The MPs-based CLEIA was performed well in the detection of urinary survivin. Urinary survivin and LAPTM4B could serve as potential biomarkers for the preliminary diagnosis of BC and RCC, and in combination they a achieved a greater diagnostic performance.

Correlation of lysosome-associated protein transmembrane-4β gene overexpression with the malignant phenotypes of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common and rapidly fatal malignancies, for which hepatitis B virus (HBV) chronic infection constitutes a major risk factor. The lysosome-associated protein transmembrane-4 β gene (LAPTM4B) is a recently identified gene that was found to be overexpressed in several types of cancer. However, the role of LAPTM4B in HCC tumorigenesis and progression has not been clearly determined. The present study demonstrated that the mRNA as well as the protein levels of LAPTM4B were significantly upregulated in HCC specimens. Patients with higher levels of LAPTM4B mRNA in their HCC tissues tended to be of a younger age, HBsAg+, with an advanced Barcelona Clinic Liver Cancer stage. Moreover, LAPTM4B mRNA expression was positively associated with serum α -fetoprotein levels. We also observed that LAPTM4B was able to promote HCC cell proliferation, migration and invasion in vitro. In conclusion, our results indicated that LAPTM4B plays an important role in the promotion of hepatocarcinogenesis and cancer progression and may serve as a biomarker for the diagnosis and monitoring of HCC.

Lysosome-associated protein transmembrane4β is involved in multidrug resistance processes of colorectal cancer

Colorectal cancer (CRC) is one of the most common reasons for cancer-associated mortality worldwide. The present study aimed to investigate the drug resistance mechanism of the oxaliplatin (OXA)-resistant HT-29 cell line (HT-29/L-OHP) and examine the expression of lysosome-associated protein transmembrane 4β (LAPTM4β), a drug resistance-associated gene. In the present study, a drug concentration gradient method was used to establish the drug-resistant HT-29/L-OHP cell line. Cell apoptosis was analyzed by flow cytometry. LAPTM4β mRNA expression was examined by reverse transcription-quantitative polymerase chain reaction analysis and LAPTM4β-35 expression was examined by western blot analysis. Cell morphology of the HT-29/L-OHP drug-resistant cell line was examined. The results indicated that the intercellular space among HT-29 cells was small, with aggregative growth while the intercellular space among HT-29/L-OHP cells was large, with scattered growth. The apoptotic rate in HT-29/L-OHP cells (11.7%) was significantly lower compared with that in HT-29 cells (17.7%) (P<0.05). LAPTM4β mRNA expression in HT-29/L-OHP cells was significantly increased compared with that in HT-29 cells (P<0.05). The relative expression of LAPTM4β-35 protein in HT-29/L-OHP cells was significantly higher compared with that inHT-29 cells (P<0.05). In conclusion, LAPTM4β may be involved in the multidrug resistance processes of CRC. Therefore, LAPTM4β may serve as a novel biomarker for drug resistance of CRC.

Association of lysosomal protein transmembrane 4 beta gene polymorphism with pancreatic carcinoma susceptibility in the Chinese population

Pancreatic carcinoma is an aggressive malignancy with particularly low 5-year survival rate. In order to improve the dismal survival rate, identification of new potential susceptibility risk factors for the prevention and early detection of pancreatic carcinoma is of utmost importance. Lysosomal protein transmembrane 4 beta has two alleles designated as LAPTM4B*1 and LAPTM4B*2. The aim of this study was to investigate the association between lysosomal protein transmembrane 4 beta gene polymorphism and the risk of pancreatic carcinoma in China. A population-based case-control analysis was performed in 233 patients with pancreatic carcinoma and 842 control subjects. The genotypes of lysosomal protein transmembrane 4 beta were determined by utilizing polymerase chain reaction based on specific primers. The χ2 test was used to analyze the differences of categorical variables and Hardy-Weinberg equilibrium. Odds ratio and 95% confidence intervals were computed using an unconditional logistic regression model. A significant difference in the frequency of LAPTM4B*2 was observed between the patients and the controls (33.05% vs 27.55%, p = 0.03). LAPTM4B*2 had a 1.33-fold (95% confidence interval: 1.04-1.71) higher risk for developing pancreatic carcinoma when compared with LAPTM4B*1 carriers. We found that the frequency of LAPTM4B*1/2 + *2/2 in pancreatic carcinoma group was higher than that in the control group (57.94% vs 48.34%, p = 0.01). However, no significant association was observed between lysosomal protein transmembrane 4 beta genotypes and gender, age, family history of cancer, smoking/alcohol status, histopathological differentiation, lymph node metastasis, clinical stage, or serum cancer antigen 19-9 level. These findings indicate that the LAPTM4B*2 allele is associated with the high risk of pancreatic carcinoma and carrying LAPTM4B*2 may be a susceptible factor to Chinese pancreatic carcinoma patients.

LAPTM4B-35、CTGF蛋白在食管胃交界部腺癌中的表达及其意义

目的

探讨溶酶体相关4次跨膜蛋白β(lysosome-associated protein transmembrane-4β, LAPTM4B)基因-35及结缔组织生长因子(connective tissue growth factor, CTGF)蛋白在食管胃交界部腺癌组织中的表达及其意义.

方法

采用免疫组织化学染色及蛋白印迹分析检测137例食管胃交界部腺癌组织中LAPTM4B-35及CTGF蛋白的表达情况, 分析蛋白表达与患者临床病理参数的关系及对患者预后的影响.

结果

LAPTM4B-35蛋白在89.1%的食管胃交界部腺癌组织中呈高表达状态, LAPTM4B-35高表达组癌细胞发生远处转移(P = 0.011)、肿瘤进展至TNM Ⅲ/Ⅳ期(P = 0.026)显著多于低表达组. CTGF蛋白在51.1%的癌组织中呈高表达状态, CTGF高表达组发生远处转移(P = 0.033)、肿瘤直径>5 cm(P = 0.021)均多于低表达组. 癌组织中LAPTM4B-35蛋白与CTGF蛋白表达之间呈正相关关系(r = 0.218, P = 0.010). 单因素生存分析显示LAPTM4B-35、CTGF蛋白高表达的患者其术后生存时间分别显著低于LAPTM4B-35、CTGF蛋白低表达的患者(双侧log-rank检验, P<0.001). LAPTM4B-35蛋白表达(P<0.001)、发生远处转移(P<0.001)、淋巴结转移(P = 0.007)、查见脉管癌栓(P = 0.022)及患者性别(P<0.001)是影响食管胃交界部腺癌患者的独立预后因子.

结论

LAPTM4B-35及CTGF蛋白的高表达与肿瘤的侵袭转移及不良预后密切相关.

Transforming growth factor β-activated kinase 1 inhibitor suppresses the proliferation in triple-negative breast cancer through TGF-β/TGFR pathway

Breast cancer is one of the most invasive cancer types in female population. The functional activity of Transforming growth factor β-activated kinase 1 (TAK1) in breast cancer progression increasingly attracts attention as it provides a potential target for antibreast cancer drug development. However, the fundamental role of TAK1 for triple-negative breast cancer (TNBC) progression and the effect of potential anti-TAK1 drug candidate needs to be further evaluated. Herein, we focused on the role of TAK1 in human breast cancer cells, and we hypothesized that the inhibition of TAK1 activation can repress the growth of human TNBC cells. We found that the TAK1 is robustly activated within cancer cell population of clinic-derived TNBC samples and the human breast cancer cell lines in culture. Furthermore, we determined the effect of 5Z-7-oxozeaenol (5Z-O), a TAK1-specific small molecule inhibitor, on proliferation of human TNBC cell line. 5Z-O treatment significantly suppressed the proliferation of human TNBC cells. Collectively, these demonstrate the role of TAK1 in human breast cancer and the antiproliferate effect of TAK1 inhibitor. Our study sets the stage for further research on TAK1 as a promising target for development of anti-TNBC drugs and therapeutic strategies.

LAPTM4B-35 is a novel prognostic factor for glioblastoma

Lysosome-associated protein transmembrane-4 beta (LAPTM4B)-35, a newly identified cancer-associated gene, is overexpressed in a wide variety of malignant tumors. However, studies of its expression and role in glioma have not yet been reported. This study aimed to investigate the expression and the role of LAPTM4B-35 in glioma and to assess its value as a prognostic factor. Seventy-seven glioma cases (Grade II in 18 patients, Grade III in 16 and Grade IV in 43) were immunohistochemically examined for LAPTM4B-35, pAkt, factor VIII and Ki-67 expressions. The LAPTM4B-35 expression score of Grade II gliomas was lower than those of Grade III-IV gliomas (p < 0.05), while the difference between Grade III and IV gliomas was not statistically significant. Of the 43 patients with glioblastoma (GBM), 27 (62.8%) had high LAPTM4B-35 expression, which was associated with high tumor micro-vessel density and pAkt activation. The median progression-free survival (PFS) of GBM patients with high LAPTM4B-35 expression was 5.13 months, significantly shorter than that of those with low LAPTM4B-35 expression (12.0 months, p < 0.0001). The median overall survival (OS) of GBM patients with high LAPTM4B-35 expression was 12.5 months, again significantly shorter than that of those with low LAPTM4B-35 expression (29.6 months, p < 0.0001). Multivariate analysis indicated LAPTM4B-35 to be an independent prognostic factor for PFS and OS of GBM patients. Our findings show LAPTM4B-35 to be strongly associated with tumor proliferation, tumor angiogenesis and poor outcomes of GBM patients, suggesting LAPTM4B-35 to potentially be applicable as a novel prognostic marker and even to possibly play a role in improving GBM treatment.

LAPTM4B: an oncogene in various solid tumors and its functions

The oncogene Lysosome-associated protein transmembrane-4β (LAPTM4B) gene was identified, and the polymorphism region in the 5′-UTR of this gene was certified to be associated with tumor susceptibility. LAPTM4B-35 protein was found to be highly expressed in various solid tumors and could be a poor prognosis marker. The functions of LAPTM4B in solid tumors were also explored. It is suggested that LAPTM4B could promote the proliferation of tumor cells, boost invasion and metastasis, resist apoptosis, initiate autophagy and assist drug resistance.

Association between LAPTM4B gene polymorphism and prostate cancer susceptibility in an Iranian population

Lysosome associated protein transmembrane 4 β (LAPTM4B) is an oncogene associated with many human cancers. In the present study we aimed to examine the possible association between LAPTM4B polymorphism and risk of prostate cancer (PCa) in an Iranian population. This case control study was performed on 168 patients with PCa and 176 controls with benign prostatic hyperplasia (BPH). Genomic DNA was extracted from whole blood and LAPTM4B genotypes were identified by polymerase chain reaction. The distributions of LAPTM4B genotypes were significantly different between PCa patients (60.7% for *1/1, 32.8% for *1/2, and 6.5% for *2/2) and controls (44.9% for *1/1, 49.4% for *1/2, and 5.7% for *2/2). Both the *1/2 and *1/2+*2/2 genotypes significantly decreased the risk of PCa compared with the *1/1 genotype (OR = 49, 95% CI = 0.31-0.77, p = 0.002 and OR = 0.53, 95% CI = 0.34-0.81, p = 0.004, respectively). The minor allele (LAPTM4B*2) was associated with a decreased risk of PCa compared with the LAPTM4B*1 allele (OR = 0.68, 95% CI = 0.48-0.96, p = 0.031). Moreover, LAPTM4B polymorphism was not associated with clinicopathological characteristics of PCa patients. The results of this study showed that LAPTM4B*2 was associated with a decreased risk of PCa but the clinicopathological characteristics of PCa were not linked to LAPTM4B polymorphism. Further studies with larger sample sizes and different ethnicities are needed to confirm our findings.

Predictive significance of combined LAPTM4B and VEGF expression in patients with cervical cancer

Lysosome-associated protein transmembrane 4ß-35 (LAPTM4B-35) is overexpressed in several solid malignancies. This study determines the expression level of LAPTM4B-35 in the cervical cancer during tumor development and progression. The present study investigated the clinicopathological significance of the coexpression of LAPTM4B-35 and VEGF in patients with cervical cancer. Immunohistochemistry was used to evaluate the expression of LAPTM4B-35 and VEGF in 62 cervical intraepithelial neoplasia (CIN) and 226 cervical carcinoma in comparison with 45 normal cervical specimens. The correlation of combined LAPTM4B-35 and VEGF with clinicopathologic characteristics was analyzed using a chi-squared test. Patient survival was determined using Kaplan-Meier method and log-rank test. A Cox regression analysis was performed to determine the prognostic significance of the factors. Combined LAPTM4B-35 and VEGF expression was significantly associated with FIGO stage (P = 0.014), tumor histologic grade (P = 0.033), lymph node metastasis (P = 0.045), and recurrence (P = 0.010). Kaplan-Meier survival analysis showed that patients with cervical cancer expressing both LAPTM4B-35 and VEGF exhibited both poor overall survival (OS) and disease-free survival (DFS) (P = 0.015 and P = 0.016, respectively). Cox analysis demonstrated that combined LAPTM4B-35 and VEGF expression was an independent factor for both OS and DFS (P = 0.015 and P = 0.016, respectively). Overexpression of LAPTM4B-35combined with positive VEGF expression may serve as a new biological marker to predict the prognosis of cervical carcinoma patients.

Lysosomal-associated Transmembrane Protein 4B (LAPTM4B) Decreases Transforming Growth Factor β1 (TGF-β1) Production in Human Regulatory T Cells

Production of active TGF-β1 is one mechanism by which human regulatory T cells (Tregs) suppress immune responses. This production is regulated by glycoprotein A repetitions predominant (GARP), a transmembrane protein present on stimulated Tregs but not on other T lymphocytes (Th and CTLs). GARP forms disulfide bonds with proTGF-β1, favors its cleavage into latent inactive TGF-β1, induces the secretion and surface presentation of GARP·latent TGF-β1 complexes, and is required for activation of the cytokine in Tregs. We explored whether additional Treg-specific protein(s) associated with GARP·TGF-β1 complexes regulate TGF-β1 production in Tregs. We searched for such proteins by yeast two-hybrid assay, using GARP as a bait to screen a human Treg cDNA library. We identified lysosomal-associated transmembrane protein 4B (LAPTM4B), which interacts with GARP in mammalian cells and is expressed at higher levels in Tregs than in Th cells. LAPTM4B decreases cleavage of proTGF-β1, secretion of soluble latent TGF-β1, and surface presentation of GARP·TGF-β1 complexes by Tregs but does not contribute to TGF-β1 activation. Therefore, LAPTM4B binds to GARP and is a negative regulator of TGF-β1 production in human Tregs. It may play a role in the control of immune responses by decreasing Treg immunosuppression.

Lysosome-associated protein transmembrane-4β-35 is a novel independent prognostic factor in small cell lung cancer

The lysosome-associated protein transmembrane-4β-35 (LAPTM4B-35) protein has been indicated to be involved in solid tumors, while its role in small cell lung cancer (SCLC) remains unknown. The aim of this study is to investigate the LAPTM4B-35 protein expression and its clinical and prognostic role in SCLC patients. A total of 88 SCLC patients who underwent radical surgery between 2002 and 2010 were enrolled in the study. The level of messenger RNA (mRNA) and protein was detected from the fresh paired tumor specimens and adjacent normal tissues. The clinicopathological and survival data were collected. And the relationship between LAPTM4B-35 and clinicopathological features was analyzed. The prognostic value of LAPTM4B-35 for SCLC was investigated by univariate and multivariate analyses. The LAPTM4B-35 was overexpressed significantly in SCLC cancer tissues. The elevated protein expression was correlated strongly with clinical stage (p = 0.012) and tumor recurrence (p = 0.023). The 5-year overall survival and disease-free survival (DFS) were significantly worse in the patients with high LAPTM4B-35 level. Multivariate Cox analysis indicated that high LAPTM4B-35 expression was an independent prognostic factor for overall survival (OS) and DFS (p = 0.017 vs p = 0.011). LAPTM4B-35 overexpression was an independent factor in SCLC prognosis, which may be considered a potential useful marker in defining the SCLC prognosis.

LAPTM4B-35, a cancer-related gene, is associated with poor prognosis in TNM stages I-III gastric cancer patients

Background

Lysosome-associated transmembrane protein 4β-35 (LAPTM4B-35), a member of the mammalian 4-tetratransmembrane spanning protein superfamily, has been reported to be overexpressed in several cancers. However the expression of LAPTM4B-35 and its role in the progression of gastric cancer (GC) remains unknown. The aim of this study was to investigate LAPTM4B-35 expression in GC, its potential relevance to clinicopathologic parameters and role of LAPTM4B-35 during gastric carcinogenesis.

Methods

In the present study, paraffin-embedded specimens with GC (n = 240, including 180 paired specimens) and 24 paired fresh frozen tissues were analyzed. qRT-PCR and immunohistochemistry (IHC) were used to analyze the expression of LAPTM4B-35 in GC. The effects of LAPTM4B-35 on GC cell proliferation, migration and invasion were determined by overexpression and knockdown assays.

Results

IHC showed that LAPTM4B-35 was expressed in 68.3% (123/180) of GC tissues, while in 16.1% (29/180) of their paired adjacent noncancerous gastric tissues (P = 0.000). LAPTM4B-35 mRNA levels in GC tissues were also significantly elevated when compared with their paired adjacent noncancerous tissues (P = 0.017). Overexpression of LAPTM4B-35 was significantly associated with degree of differentiation, depth of invasion, lymphovascular invasion and lymph node metastasis (P<0.05). Kaplan-Meier survival curves revealed that patients with LAPTM4B-35 expression had a significant decrease in overall survival (OS) in stages I-III GC patients (P = 0.006). Multivariate analysis showed high expression of LAPTM4B-35 was an independent prognostic factor for OS in stage I-III GC patients (P = 0.025).

Conclusion

These findings indicate that LAPTM4B-35 overexpression may be related to GC progression and poor prognosis, and thus may serve as a new prediction marker of prognosis in GC patients.

Lysosomal-associated protein transmembrane 4 Beta-35 overexpression is a novel independent prognostic marker for gastric carcinoma

OBJECTIVE

The purpose of this work was to analyze the relationships between the expression status of Lysosomal-associated protein transmembrane-4 beta 35 (LAPTM4B-35) in cancerous tissues and clinicopathological characteristics and prognosis of the patients with gastric carcinoma (GC).

METHODS

The GC samples from 157 patients in a discovery cohort and 148 patients in a testing cohort with follow-up data were used to validate the feasibility of expression of LAPTM4B-35 protein in predicting GC prognosis. Immunohistochemical staining was used to determine the expression of LAPTM4B-35 protein in precancerous gastric lesions and gastric carcinomas. The correlation between the expression of LAPTM4B-35 and clinicopathologic characteristics of patients with gastric carcinoma was analyzed using chi-square test. Univariate and multivariate analyses were performed to determine the association between LAPTM4B-35 expression and prognosis.

RESULTS

LAPTM4B-35 expression was increased steadily in sequential stages of precancerous gastric lesions. Positive LAPTM4B-35 expression was more frequently detected in patients with distant metastasis (P = 0.023) and III+IV TNM stages (P = 0.042) in the discovery cohort. Kaplan-Meier survival curves and univariate analysis showed that expression of LAPTM4B-35 had a significant impact on overall survival of patients with gastric carcinoma in discovery cohort (P<0.001) and testing cohort (P = 0.001). LAPTM4B-35 expression was an independent prognostic indicator for the overall survival of patients with gastric carcinoma in both cohorts.

CONCLUSIONS

The present research demonstrated that LAPTM4B-35 over-expression was an independent factor in gastric carcinoma prognosis. LAPTM4B gene may be a useful target of interventions slowing the progression of precancerous gastric lesions and a new therapy method to improve the prognosis of gastric carcinoma.

LAPTM4B is a PtdIns(4,5)P2 effector that regulates EGFR signaling, lysosomal sorting, and degradation

Lysosomal degradation is essential for the termination of EGF-stimulated EGF receptor (EGFR) signaling. This requires EGFR sorting to the intraluminal vesicles (ILVs) of multi-vesicular endosomes (MVEs). Cytosolic proteins including the ESCRT machineries are key regulators of EGFR intraluminal sorting, but roles for endosomal transmembrane proteins in receptor sorting are poorly defined. Here, we show that LAPTM4B, an endosomal transmembrane oncoprotein, inhibits EGF-induced EGFR intraluminal sorting and lysosomal degradation, leading to enhanced and prolonged EGFR signaling. LAPTM4B blocks EGFR sorting by promoting ubiquitination of Hrs (an ESCRT-0 subunit), which inhibits the Hrs association with ubiquitinated EGFR. This is counteracted by the endosomal PIP kinase, PIPKIγi5, which directly binds LAPTM4B and neutralizes the inhibitory function of LAPTM4B in EGFR sorting by generating PtdIns(4,5)P2 and recruiting SNX5. PtdIns(4,5)P2 and SNX5 function together to protect Hrs from ubiquitination, thereby promoting EGFR intraluminal sorting. These results reveal an essential layer of EGFR trafficking regulated by LAPTM4B, PtdIns(4,5)P2 signaling, and the ESCRT complex and define a mechanism by which the oncoprotein LAPTM4B can transform cells and promote tumor progression.

LAPTM4B-35 protein as a potential therapeutic target in gastric cancer

The objective of this study is to investigate lysosome-associated protein transmembrane 4b-35 (LAPTM4B-35) protein expression in gastric cancer and its clinical implications. LAPTM4B-35 protein expression in 652 gastric cancer specimens and matched adjacent non-cancerous tissues was evaluated by immunohistochemical staining. Subsequently, the relationship between LAPTM4B-35 protein expression, clinical pathological parameters, and prognosis of gastric cancer was determined. LAPTM4B-35 protein expression was significantly higher in gastric cancer tissue compared to adjacent non-cancerous tissues (P = 0.001). In total, 417 (63.96 %) of the 652 gastric cancer cases demonstrated high LAPTM4B-35 protein expression. Multiple regression analysis was performed to identify the factors related to lymph node metastasis. As a result, age, tumor number, primary tumor category, histological type, histological growth pattern, and LAPTM4B-35 protein expression were found to be significantly related to lymph node metastasis (P = 0.010, 0.001, 0.032, 0.001, 0.001, and 0.001, respectively). Survival analysis identified that LAPTM4B-35 protein expression was also an independent prognostic factor (P = 0.001). LAPTM4B-35 was highly expressed in gastric cancer and may be a potential target for the management of gastric cancer.

Relationship Between LAPTM4B Gene Polymorphism and Susceptibility of Malignant Melanoma in Chinese Patients

Lysosomal-associated protein transmembrane 4 beta (LAPTM4B) is known as an oncogene associated with many human malignant tumors. There are two alleles of the gene, LAPTM4B*1 and LAPTM4B*2. Previous studies have shown that LAPTM4B polymorphism contributes to the risk of many cancers. This case-control study was to investigate the relationship between LAPTM4B gene polymorphism and susceptibility of malignant melanoma. The genotypes of LAPTM4B were determined in 617 control subjects and 220 patients with malignant melanoma by utilizing polymerase chain reaction based on specific primers. The genotypic distribution of LAPTM4B and Hardy–Weinberg equilibrium were analyzed by χ² test. Odds ratio and 95% confidence interval was calculated by unconditional logistic regression. The distributions of LAPTM4B genotypes were significantly different between melanoma patients (45.9% for *1/1, 46.4% for *1/2 and 7.7 for *2/2) and controls (54.5% for *1/1, 39.9% for *1/2 and 5.7 for *2/2). LAPTM4B *1/2 and LAPTM4B *2/2 had a 1.396-fold and 1.619-fold higher risk for melanoma occurrence than *1/1, and subjects with LAPTM4B*2 have a 1.308-fold higher risk than LAPTM4B*1 carriers. No association between LAPTM4B genotypes and gender, age, subtype, Clark level of invasion, Breslow thickness, ulceration, clinical stage, and C-KIT, BRAF gene mutation status was observed. LAPTM4B*2 is associated with the high risk of malignant melanoma and carrying LAPTM4B *2 may be a susceptible factor to Chinese melanoma patients.

Overexpression of LAPTM4B is correlated with tumor angiogenesis and poor prognosis in non-small cell lung cancer

Lysosome-associated protein transmembrane-4 beta (LAPTM4B) is a novel oncogene, which has been indicated to be dramatically overexpressed in various malignant tumors. The aims of this study were to detect LAPTM4B protein expression in patients with non-small cell lung cancer (NSCLC) and then analyze the relationships of LAPTM4B protein with clinicopathologic factors, tumor angiogenesis and prognosis with SPSS statistical software. Immunohistochemistry was used to examine the expression of LAPTM4B and CD34 proteins in NSCLC tissues, and its results showed that LAPTM4B protein expression in NSCLC tissues was significantly higher than that in normal lung tissues (P < 0.001). Of the186 NSCLC cases, 129 (69.35 %) had strong expression of LAPTM4B protein, which was associated with histopathologic differentiation (P = 0.017), lymph node metastasis (P = 0.001) and TNM stage (P = 0.046), as well as the microvessel density (MVD) (P = 0.019). Kaplan-Meier survival analysis revealed that patients with strong LAPM4B protein expression and high MVD might have poor overall survival (OS; P = 0.001, P = 0.002, respectively) and disease-free survival (DFS; P = 0.002, P = 0.038, respectively). Multivariate analysis demonstrated that LAPTM4B protein was an independent prognostic marker for OS and DFS of NSCLC patients (P = 0.037, P = 0.046, respectively). These findings illustrated that LAPTM4B protein was closely associated with NSCLC progression, angiogenesis and poor prognosis, suggesting that LAPTM4B protein could be applied not only in predicting patient's outcome, but also in antiangiogenic therapy as a possible novel target molecule.

LAPTM4B polymorphism is associated with non‑small cell lung cancer susceptibility and prognosis

Lysosome-associated protein transmembrane-4β (LAPTM4B) is a novel cancer-related gene that is upregulated in many tumors, and which plays important roles in carcinogenesis. It has two alleles, LAPTM4B 1 and LAPTM4B 2. LAPTM4B 1 contains only one copy of a 19-bp sequence in the first exon, whereas LAPTM4B 2 contains two tight tandem segments. Previous studies have shown that LAPTM4B 2 is a risk factor for susceptibility and prognosis of many tumors. The present study investigated the relationship between LAPTM4B polymorphism and non-small cell lung cancer (NSCLC) susceptibility and prognosis. We identified LAPTM4B genotypes with polymerase chain reaction (PCR) in peripheral blood samples. In the adjusted multivariate logistic regression analysis, we found that LAPTM4B 1/2, LAPTM4B 2/2 exhibited 1.48-fold [95% confidence interval (CI), 1.076-2.037] and 2.855-fold (95%CI, 1.722-4.734) increases in the risk of developing NSCLC compared with non-LAPTM4B 2 carriers. Furthermore, our results showed that overall survival time and disease-free survival time of patients with LAPTM4B 2 were significantly shorter than in patients carrying LAPTM4B 1 (P=0.001 and P=0.001, respectively). In addition, multivariate Cox regression analysis revealed that LAPTM4B 2 was also an independent prognostic factor for NSCLC. These results suggest that LAPTM4B polymorphisms may be a prospective marker for evaluating the risk and prognosis of NSCLC.

cAMP responsive element binding protein-1 is a transcription factor of lysosomal-associated protein transmembrane-4 Beta in human breast cancer cells

Lysosomal-associated protein transmembrane-4 beta (LAPTM4B) is a potential proto-oncogene, whose overexpression is involved in cancer occurrence and progression. Its transcript is up-regulated in various types of solid tumors including breast cancer. However, its transcriptional regulation mechanism is still unclear. To investigate the mechanism of transcriptional regulation of LAPTM4B in human breast cancer cells, a series of luciferase reporter constructs and construct with mutated binding site for cAMP responsive element binding protein-1 (CREB1) were generated by PCR amplification and transiently transfected into breast cancer cells to determine the transcriptional activities of different promoter regions. The +10+292 promoter region was possessed the highest transcriptional activity. The ability of CREB1 to bind the LAPMT4B promoter was confirmed by electrophoretic mobility shift assay, super-shift and RNA interference experiments. Our study identified the core promoter region responsible for constitutive expression of LAPTM4B and clarified that CREB1 played an important role in LAPTM4B transcriptional regulation in human breast cancer cells.