LAPTM4B-35 overexpression is a risk factor for tumor recurrence and poor prognosis in hepatocellular carcinoma

[Serum LAPTM4B-35 protein as a novel diagnostic marker for hepatocellular carcinoma]

OBJECTIVE

LAPTM4B-35 protein is one of the isoforms that are encoded by a cancer driver gene, LAPTM4B. This gene was primarily found and identified in our lab of Peking University School of Basic Medical Sciences. The LAPTM4B-35 protein and its encoded mRNA are significantly over-expressed in a variety of cancers, such as hepatocellular carcinoma (HCC), lung cancers (including non small-cell lung cancer and small-cell lung cancer), stomach cancer, colorectal carcinoma, pancreatic cancer, gallbladder cancer, cholangiocarcinoma, breast cancer, prostate cancer, ovarian cancer, cervical cancer, endometrial cancer, and so on. It has firmly demonstrated through lab experiments either in vivo or in vitro, as well as clinical studies that the over-expression of LAPTM4B-35 can promote cancer growth, metastasis, and multidrug resistance. Specially, the expressive level of LAPTM4B-35 is associa-ted with recurrence of HCC. The aim of this study is to identify the release of LAPTM4B-35 protein from hepatocellular carcinoma into blood of HCC patients and into the medium of cultured HCC cells, and to identify its possible form of LAPTM4B-35 protein existed in blood and cell culture medium, as well as to explore the possibility of LAPTM4B-35 protein as a novel HCC biomarker for diagnosis of HCC and prognosis of HCC patients.

METHODS

Immunobloting (Western blot) and enzyme-linked immunosorbent assay (ELISA) were used for identification of LAPTM4B-35 protein in the blood of HCC patients and normal individuals. Ultrafiltration and ultracentrifugation were used to isolate and purify exosomes from the culture medium of HCC cells.

RESULTS

LAPTM4B-35 protein existed in the blood from HCC patients and normal donors that were demonstrated through Western blot and ELISA. LAPTM4B-35 was also released into the culture medium of HCC cells in the form of exosomes. Preliminary experiments showed that the average and the median of LAPTM4B-35 protein level in the blood of HCC patients (n=43) were both significantly higher than that in the blood of normal donors (n=33) through sandwich ELISA.

CONCLUSION

It is promising that the LAPTM4B-35 protein which is released from HCC cells in the form of exosomes into their extraenvironment may be exploited as a novel cancer biomarker for HCC serological diagnosis.

Identification of Lysosome-Associated Protein Transmembrane-4 as a Novel Therapeutic Target for Osteosarcoma Treatment

OBJECTIVE

The aim of the study is to evaluate the expression of lysosome-associated protein transmembrane-4 (LAPTM4B) in human osteosarcoma tissue samples collected in our hospital, and to explore the possible correlations between the clinical pathological features of osteosarcoma patients and LAPTM4B expression.

METHODS

Immunohistochemical (IHC) assays were performed to detect the expression levels of LAPTM4B in 62 tissue samples of osteosarcoma tissues and corresponding non-tumor tissues. According to LAPTM4B staining intensity in tumor tissues, osteosarcoma patients were classified into LAPTM4B high expression and low expression groups. In addition, the potential correlations between LAPTM4B expression levels and clinical pathological features were evaluated. In addition, we detected the effects of LAPTM4B on the proliferation and invasion of esteosarcoma cells through colony formation assay and transwell assay, respectively. We further explored the potential effects of LAPTM4B on tumor growth and metastasis using in vivo animal model.

RESULTS

We revealed that LAPTM4B was highly expressed in human osteosarcoma tissues. We determined the significance between LAPTM4B and clinical features, including the tumor size (P = 0.004*) and the clinical stage (P = 0.035*) of osteosarcoma patients. Our results further demonstrated that ablation of LAPTM4B obviously blocked the proliferation and invasion of osteosarcoma cells in vitro and restrained tumor growth and metastasis in mice.

CONCLUSION

We investigated the potential involvement of LAPTM4B in osteosarcoma progression and confirmed LAPTM4B as a novel therapeutic target for osteosarcoma.

A robust twelve-gene signature for prognosis prediction of hepatocellular carcinoma

Background

The prognosis of hepatocellular carcinoma (HCC) patients remains poor. Identifying prognostic markers to stratify HCC patients might help to improve their outcomes.

Methods

Six gene expression profiles (GSE121248, GSE84402, GSE65372, GSE51401, GSE45267 and GSE14520) were obtained for differentially expressed genes (DEGs) analysis between HCC tissues and non-tumor tissues. To identify the prognostic genes and establish risk score model, univariable Cox regression survival analysis and Lasso-penalized Cox regression analysis were performed based on the integrated DEGs by robust rank aggregation method. Then Kaplan-Meier and time-dependent receiver operating characteristic (ROC) curves were generated to validate the prognostic performance of risk score in training datasets and validation datasets. Multivariable Cox regression analysis was used to identify independent prognostic factors in liver cancer. A prognostic nomogram was constructed based on The Cancer Genome Atlas (TCGA) dataset. Finally, the correlation between DNA methylation and prognosis-related genes was analyzed.

Results

A twelve-gene signature including SPP1, KIF20A, HMMR, TPX2, LAPTM4B, TTK, MAGEA6, ANX10, LECT2, CYP2C9, RDH16 and LCAT was identified, and risk score was calculated by corresponding coefficients. The risk score model showed a strong diagnosis performance to distinguish HCC from normal samples. The HCC patients were stratified into high-risk and low-risk group based on the cutoff value of risk score. The Kaplan-Meier survival curves revealed significantly favorable overall survival in groups with lower risk score (P < 0.0001). Time-dependent ROC analysis showed well prognostic performance of the twelve-gene signature, which was comparable or superior to AJCC stage at predicting 1-, 3-, and 5-year overall survival. In addition, the twelve-gene signature was independent with other clinical factors and performed better in predicting overall survival after combining with age and AJCC stage by nomogram. Moreover, most of the prognostic twelve genes were negatively correlated with DNA methylation in HCC tissues, which SPP1 and LCAT were identified as the DNA methylation-driven genes.

Conclusions

We identified a twelve-gene signature as a robust marker with great potential for clinical application in risk stratification and overall survival prediction in HCC patients.

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.

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.

The Functional Role of Prostate Cancer Metastasis-related Micro-RNAs

The mortality of patients with hormone-resistant prostate cancer can be ascribed to a large degree to metastasis to distant organs, predominantly to the bones. In this review, we discuss the contribution of micro-RNAs (miRs) to the metastatic process of prostate cancer. The criteria for selection of miRs for this review were the availability of preclinical in vivo metastasis-related data in conjunction with prognostic clinical data. Depending on their function in the metastatic process, the corresponding miRs are up- or down-regulated in prostate cancer tissues when compared to matching normal tissues. Up-regulated miRs preferentially target suppressors of cytokine signaling or tumor suppressor-related genes and metastasis-inhibitory transcription factors. Down-regulated miRs promote epithelial-mesenchymal transition or mesenchymal-epithelial transition and diverse pro-metastatic signaling pathways. Some of the discussed miRs exert their function by simultaneously targeting epigenetic pathways as well as cell-cycle-related, anti-apoptotic and signaling-promoting targets. Finally, we discuss potential therapeutic options for the treatment of prostate cancer-related metastases by substitution or inhibition of miRs.

LAPTM4B facilitates tumor growth and induces autophagy in hepatocellular carcinoma

Background: Hepatocellular carcinoma (HCC) is one of the most frequent cancers and the third leading cause of cancer-related deaths. It has been reported that lysosomal associated transmembrane protein LAPTM4B expression is significantly upregulated in human cancers and closely associated with tumor initiation and progression.

Purpose: We aimed to reveal the relevance of LAPTM4B and the pathogenesis of HCC. Methods: Cell viability assessment, colony formation assay, in vivo xenograrft model, microarray, real-time PCR, immunofluorescence and western blot analysis were applied.

Results: Our results demonstrated that LAPTM4B promoted HCC cell proliferation in vitro and tumorigenesis in vivo. Additionally, upon starvation conditions, LAPTM4B facilitated cell survival, inhibited apoptosis and induced autophagic flux. Expression profiling coupled with gene ontology (GO) analysis revealed that 159 gene downregulated by LAPTM4B silencing was significantly enriched in response to nutrient and some metabolic processes. Moreover, LAPTM4B activated ATG3 transcription to modulate HCC cell apoptosis and autophagy.

Conclusion: Our findings demonstrate that LAPTM4B acts as an oncogene that promotes HCC tumorigenesis and autophagy, and indicate that LAPTM4B may be used as a novel therapeutic target for HCC treatment.

Selecting patients with hepatocellular carcinoma for liver transplantation: incorporating tumor biology criteria

Liver transplantation (LT) is the optimal therapeutic option for patients with liver cirrhosis and hepatocellular carcinoma (HCC). Due to universal donor shortage, only the patients with limited tumor burden (under the so-called Milan criteria) are considered as potential candidates for LT in most institutions. It is expected that in the near future, more liver grafts will be available for patients with HCC due to the implementation of new direct antivirals against hepatitis C, leaving a prone scenario to consider expanding Milan criteria. A moderate expansion of Milan criteria could be implemented without increasing the risk of tumor recurrence if patients with favorable biological behavior are carefully selected. Incorporating information regarding tumor biology in the decision-making algorithm would result in a more rational use of LT in patients with HCC. In the present review, surrogate markers of tumor biology are critically evaluated as potential tools to be combined with existing radiological criteria. In addition, the current state of liquid biopsy is discussed, as this cutting-edge technology may reshape the management of HCC in the upcoming years.

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.

Expression signature of lysosomal-associated transmembrane protein 4B in hepatitis C virus-induced hepatocellular carcinoma

INTRODUCTION

Hepatocellular carcinoma is a lethal disease worldwide and therefore the establishment of novel diagnostic biomarkers is imperative. In this study, it was hypothesized that an abnormal expression of the lysosomal-associated protein transmembrane 4 beta ( LAPTM4B) gene is crucial in the pathogenesis of hepatitis C virus-mediated hepatocellular carcinoma; hence we investigated the expression profile of LAPTM4B in hepatitis C virus-induced hepatocellular carcinoma.

METHODS

A group of 189 consecutive patients (hepatitis C virus-related hepatocellular carcinoma as tumor cases; n=93, hepatitis C virus-related cirrhotics as disease controls; n=96) opting for living donor liver transplantation as a therapeutic surgical regimen were recruited with informed consent. Additionally, paired adjacent non-tumorous tissues (n=93) obtained from cases were also included. Serum LAPTM4B protein concentrations were assessed by third-generation enzyme-linked immunosorbent assay and LAPTM4B mRNA, and protein expressions at tissue level were determined by quantitative real time reverse transcription-polymerase chain reaction (qRT-PCR) and immunohistochemistry techniques, respectively.

RESULTS

LAPTM4B protein concentrations in sera of patients were higher ( p<0.001) in tumor cases (1.25±0.25 ng/ml) compared to disease controls (0.53±0.28 ng/ml). Our study also depicts positive clinicopathological correlations between alpha-fetoprotein titers (b=0.65; p<0.001), quantitative hepatitis C virus RNA copies (b=0.33; p<0.001), and LAPTM4B protein concentrations, all in sera of patients. In addition, qRT-PCR and immunohistochemistry analyses revealed a significantly higher ( p<0.05) tissue LAPTM4B mRNA and protein expression, respectively, in tumor cases rather than in non-tumorous tissues and disease controls.

CONCLUSIONS

Together, our results illustrate the LAPTM4B gene as a diagnostic biomarker in patients with hepatocellular carcinoma having documented evidence of chronic hepatitis C virus infection.

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.

Targeting a novel cancer-driving protein (LAPTM4B-35) by a small molecule (ETS) to inhibit cancer growth and metastasis

Our previous studies demonstrated that LAPTM4B-35 is overexpressed in a variety of solid cancers including hepatocellular carcinoma (HCC), and is an independent factor for prognosis. LAPTM4B-35 overexpression causes carcinogenesis and enhances cancer growth, metastasis and multidrug resistance, and thus may be a candidate for therapeutic targeting. The present study shows ethylglyoxal bisthiosemicarbazon (ETS) has effective anticancer activity through LAPTM4B-35 targeting. Bel-7402 and HepG2 cell lines from human HCC were used as cell models in which LAPTM4B-35 is highly expressed, and a human fetal liver cell line was used as a control. The results showed ETS has a specific and pronounced lethal effect on HCC cells, but not on fetal liver cells in culture. ETS also attenuated growth and metastasis of human HCC xenograft in nude mice, and extended the life span of mice with HCC. ETS induced HCC cell apoptosis, and upregulated a large number of proapoptotic genes and downregulated antiapoptotic genes. When endogenous overexpression of LAPTM4B-35 was knocked down with RNAi, the killing effect of ETS on HepG2 cells was significantly attenuated. ETS also inhibited phosphorylation of LAPTM4B-35 Tyr285, which involves in activation of the PI3K/Akt signaling pathway induced by LAPTM4B-35 overexpression. In addition, the induction of alterations in quantity of c-Myc, Bcl-2, Bax, cyclinD1 and Akt-p molecules in HepG2 cells by LAPTM4B-35 overexpression could be reversed by ETS.

CONCLUSION

ETS is a promising candidate for treatment of HCC through LAPTM4B-35 protein targeting.

Sperm-associated antigen 9 is upregulated in hepatocellular carcinoma tissue and enhances QGY cell proliferation and invasion in vitro

The incidence and mortality rates of hepatocellular carcinoma (HCC) are higher in China compared with in other countries. Further research is required in order to improve the diagnosis and treatment of HCC. Sperm-associated antigen 9 (SPAG9) protein has been revealed to serve an important function in cancer progression; however, the underlying mechanisms remain to be elucidated. The present study investigated the expression level of SPAG9 in HCC tissues using quantitative-polymerase chain reaction, immunohistochemistry and western blotting, and the results demonstrated that SPAG9 was overexpressed in HCC tissues compared with the adjacent non-cancerous tissues. To explore the potential mechanisms underlying SPAG9 in HCC, the effect of SPAG9 on cell proliferation, cell cycle, migration and invasion capacities were investigated in the QGY HCC cell line by RNA interference. It was revealed that inhibition of SPAG9 mRNA in QGY cells significantly inhibited the expression level of SPAG9 compared with the control. Depletion of SPAG9 expression decreased cell proliferation (P<0.01) and increased the percentage of cells in the G₁/G₂ cell cycle phase. The percentage of cells in the S phase was decreased, and cell migration and invasion capabilities in vitro were reduced (P<0.01). In summary, the results of the present study suggested that SPAG9 was upregulated in HCC and may serve an important function in cancer cell proliferation, differentiation and invasion. Whether SPAG9 is a potential diagnostic marker and therapeutic target of human HCC requires additional study.

The Transcription Factor AP4 Promotes Oncogenic Phenotypes and Cisplatin Resistance by Regulating LAPTM4B Expression

Lysosomal-associated protein transmembrane-4 beta (LAPTM4B) is a novel oncogene, whose overexpression is involved in cancer occurrence and progression. However, the mechanism of LAPTM4B transcriptional regulation remains unclear. In this study, the results of transcription factor (TF) profiling plate arrays indicated that AP4 was a potential transcription factor regulating LAPTM4B expression. LAPTM4B was positively correlated with AP4 and they were both associated with poor overall and disease-free survival. Luciferase and electrophoretic mobility shift assay assays confirmed that AP4 directly bound to the polymorphism region of LAPTM4B promoter and modulated its transcription. Functionally, AP4 promoted cell proliferation, migration, invasion, and assisted drug resistance in part through upregulation of LAPTM4B. Taken together, these findings identify LAPTM4B as a direct AP4 target gene and the interaction of AP4 and LAPTM4B plays an important role in breast cancer progression.Implications: This study demonstrates that AP4 promotes cell growth, migration, invasion, and cisplatin resistance through upregulation of LAPTM4B expression, thus representing an attractive therapeutic target for breast cancer. Mol Cancer Res; 16(5); 857-68. ©2018 AACR.

Regulator of G-protein signaling 5 enhances portal vein invasion in hepatocellular carcinoma

Portal vein invasion (PVI) is a major prognostic factor in hepatocellular carcinoma (HCC). The aim of the present study was to identify molecules that regulate PVI. Sections of cancerous tissue, paired noncancerous tissue and the PVI area were collected from 3 frozen HCC sections, using laser microdissection. The present study focused on 3 upregulated molecules, integrin β3 (ITGB3), secreted phosphoprotein 1 (SPP1) and regulator of G-protein signaling 5 (RGS5), and 2 molecules that were downregulated in PVI tissue compared with cancer tissue, metallothionein 1G (MT1G) and metallothionein 1H (MT1H), as determined by cDNA microarray analysis. Reverse transcription-quantitative polymerase chain reaction analysis of 32 HCC cases revealed that RGS5 mRNA levels were significantly increased and MT1 G and MT1H mRNA levels were significantly decreased in cancerous tissue compared with noncancerous tissue. However, there was no significant difference in ITGB3 and SPP1 expression. There were no significant differences between the expression of these molecules and any clinicopathologic factors, including PVI. Immunohistochemical staining for RGS5 in 60 HCC cases demonstrated that RGS5 protein levels were higher in cancerous tissue compared with paired noncancerous tissue in 63.3% of HCC cases. Furthermore, high expression of RGS5 in cancerous tissue was significantly associated with PVI and tended to be associated with intrahepatic metastasis. Confluent multinodular type was significantly more frequent in cases with high expression of RGS5 in the cancerous tissue. Therefore, RGS5 may be a useful prognostic biomarker as well as a potential target of molecular therapy to treat HCC.

Beclin1 antagonizes LAPTM4B-mediated EGFR overactivation in gastric cancer cells

Beclin1 is an essential autophagy regulator and a haploinsufficient tumor-suppressor. Reduced Berclin1 expression has been associated with many types of human malignancies including gastric cancer. However, the mechanism of how Beclin1 represses tumorigenesis of gastric cancer remains elusive. In recent proteomics study, we found that Beclin1 is associated with Lysosome-associated transmembrane protein 4β (LAPTM4B). LAPTM4B plays an important role in promoting the growth and proliferation of tumor cells, it is overexpressed in a variety of solid tumors and serves as a biomarker for tumor therapy. Further analysis showed that Beclin1 interacts with both the N- and C-termini of LAPTM4B and this interaction is independent of Vps34 complex. We demonstrated that Beclin1 competes with Epidermal growth factor receptor (EGFR) for LAPTM4B binding and Beclin1 can repress the LAPTM4B mediated EGFR activation and gastric cancer cell growth. Taken together, our study proposes a role of Beclin1 in repressing gastric cancer through disrupting the oncogenic promoting function of LAPTM4B.

Relationship between LAPTM4B Gene Polymorphism and Prognosis of Patients following Tumor Resection for Colorectal and Esophageal Cancers

BACKGROUND

Lysosome-associated transmembrane-4 beta (LAPTM4B) is an oncogene that participates tumorgenesis in a variety of human solid tumors, and it has two alleles named as LAPTM4B*1 and *2. The present study aimed to identify the association of LAPTM4B genotype with clinicopathological features and prognosis in colorectal and esophageal cancer patients.

METHOD

Genotypes of LAPTM4B were determined by PCR in 167 colon cancer cases (72 patients in a discovery cohort and 95 patients in a testing cohort), 160 rectal cancer cases and 164 esophageal cancer cases. Association between the LAPTM4B gene polymorphism and clinicopathological variables was calculated by Chi-square test or Fisher's exact test. Patient survival differences were calculated by the Kaplan-Meier method. Prognostic factors were determined with Log-rank test and Cox regression model.

RESULTS

LAPTM4B *1/1 was more frequently detected in colon cancer patients with lymph node metastasis and TNM III+IV stages in total colon cancer (discovery + testing cohorts). LAPTM4B *2/2 decreased in recurrent patients in total colon cancer patients (P = 0.045). Kaplan-Meier survival curves and Log-rank test showed that LAPTM4B*1 was correlated with shorter overall survival (OS) in discovery and testing cohorts of colon cancer (P = 0.0254 and 0.0292, respectively), but not in rectal and esophageal cancer cases (P = 0.7669 and 0.9356, respectively). Multivariate analysis showed that LAPTM4B genotype was an independent prognostic factor for OS in total colon cancer [P = 0.004, hazard ratio (HR) = 0.432; 95% confidence interval (CI) = 0.243-0.768], but not in rectal and esophageal cancers (P = 0.791, HR = 1.073, 95% CI = 0.638-1.804 and 0.998, HR = 1.000, 95% CI = 0.663-1.530, respectively).

CONCLUSION

These findings suggested that LAPTM4B allele *1 was a risk factor associated with poor prognosis in patients with colon cancer, but not in patients with rectal or esophageal cancers. LAPTM4B genotype status might be a useful prognostic indicator for patients that need surgical operation in colon cancer.

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.

miR-188-5p inhibits tumour growth and metastasis in prostate cancer by repressing LAPTM4B expression

Elucidation of the molecular targets and pathways regulated by the tumour-suppressive miRNAs can shed light on the oncogenic and metastatic processes in prostate cancer (PCa). Using miRNA profiling analysis, we find that miR-188-5p was significantly down-regulated in metastatic PCa. Down-regulation of miR-188-5p is an independent prognostic factor for poor overall and biochemical recurrence-free survival. Restoration of miR-188-5p in PCa cells (PC-3 and LNCaP) significantly suppresses proliferation, migration and invasion in vitro and inhibits tumour growth and metastasis in vivo. We also find overexpression of miR-188-5p in PC-3 cells can significantly enhance the cells' chemosensitivity to adriamycin. LAPTM4B is subsequently identified as a direct target of miR-188-5p in PCa, and is found to be significantly over-expressed in PCa. Knockdown of LAPTM4B phenotypically copies miR-188-5p-induced phenotypes, whereas ectopic expression of LAPTM4B reverses the effects of miR-188-5p. We also find that restoration of miR-188-5p can inhibit the PI3K/AKT signaling pathway via the suppression of LAPTM4B. Taken together, this is the first report unveils that miR-188-5p acts as a tumour suppressor in PCa and may therefore serve as a useful therapeutic target for the development of new anticancer therapy.

HES5 promotes cell proliferation and invasion through activation of STAT3 and predicts poor survival in hepatocellular carcinoma

OBJECTIVES

HES5 is a member of the basic helix-loop-helix (bHLH) family of transcription factors, and involved in cell differentiation and proliferation in a variety of tissues other than HCC. Therefore, we have characterized HES5 and investigated its role during hepatocarcinogenesis.

METHODS

We first examined the expression of HES5 in eight paired frozen HCC and adjacent noncancerous liver tissues by Western blot. Immunohistochemistry was performed to confirm our results in 58 HCC samples and evaluated the relativity between the expression of HES5 and clinicopathological variables and estimated the prognostic significance. Moreover, Western blot examined the expression of downstream proteins by siRNA HES5. Flow cytometer assay was performed to investigate the role of HES5 in the process of HCC.

RESULTS

We found that HES5 was upregulated in HCC specimens. The data showed that high expression of HES5 was tightly associated with histological grade (P<0.01) and metastasis (P<0.01), and positively correlated with proliferation marker Ki-67 (P<0.01). Moreover, the results show that abnormal expression of HES5 influences cell growth and cell cycle of HCC cell lines. Furthermore, HES5 knockdown resulted in the reduction of p-STAT3.

CONCLUSION

These results suggested that suppression of the HES5 leading to inhibition of proliferation may be one of the mechanisms against HCC.

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.

The relationship between LAPTM4B polymorphisms and cancer risk in Chinese Han population: a meta-analysis

LAPTM4B is a newly cloned gene that shows an active role in many solid tumors progression in substantial researches, mainly through the autophage function. Accumulated studies have been conducted to determine the association of LAPTM4B polymorphism with cancer risk. While the results are inconsistent, we conducted the meta-analysis to determine the strength of the relationship. Results showed that allele*2 carriers exhibited a significantly increased risk of cancer development with comparison to allele*1 homozygote (for *1/2, OR = 1.55, 95% CI 1.367-1.758; for *2/2, OR = 2.093, 95%CI 1.666-2.629; for *1/2 + *2/2, OR = 1.806, 95%CI 1.527-2.137). We also observed a significant association between *2/2 homozygote and cancer risk with comparison to allele*1 containing genotypes (OR = 1.714, 95%CI 1.408-2.088). Allele*2 is a risk factor for cancer risk (OR = 1.487, 95%CI 1.339-1.651). Stratified analysis by tumor type exhibits the significant association of this genetic variants with various cancers. In conclusion, LAPTM4B polymorphism is associated with cancer risk and allele*2 is a risk factor.

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.

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.

Overexpression of SPAG9 correlates with poor prognosis and tumor progression in hepatocellular carcinoma

Sperm-associated antigen 9 (SPAG9) was reported as a novel biomarker for several cancers and associated with the malignant behavior of cancer cells. However, its expression pattern and biological role in human hepatocellular carcinoma (HCC) have not been reported. In the present study, we analyzed SPAG9 expression in human HCC tissues by immunohistochemistry and found that SPAG9 overexpression is correlated with tumor stage (p < 0.001), tumor multiplicity (p = 0.019), tumor size (p = 0.034), AFP levels (p = 0.006), and tumor relapse (p = 0.0017). Furthermore, SPAG9 overexpression is correlated with poor overall survival (p < 0.001) and relapse-free survival (p = 0.002). Transfection of SPAG9 small interfering RNA (siRNA) was performed in Bel-7402 cell line. Colony formation and MTT showed that SPAG9 siRNA knockdown inhibited HCC cell proliferation. We also found that SPAG9 depletion could increase cell apoptosis. In addition, the level of cyclin D1 and cyclin E protein expression was downregulated after siRNA treatment. In conclusion, SPAG9 is overexpressed in human HCC and serves as a prognostic marker. SPAG9 contributes to cancer cell growth through regulation of cyclin proteins.

Rsf-1 overexpression serves as a prognostic marker in human hepatocellular carcinoma

Rsf-1 (HBXAP) was recently reported to be overexpressed in various cancers and associated with the malignant behavior of cancer cells. However, the expression of Rsf-1 and its clinical significance in human hepatocellular carcinoma (HCC) have not been reported. In the present study, we analyzed the expression pattern of Rsf-1 in human HCC tissues and found that Rsf-1 was overexpressed in 41.1 % of HCC specimens. There was a significant association between Rsf-1 overexpression and tumor stage (p = 0.0322), AFP (p = 0.0184), and tumor relapse (p = 0.0112). Furthermore, Rsf-1 overexpression correlated with poor overall survival in HCC patients (p < 0.001). Rsf-1 overexpression could serve as an independent predictor for poor recurrence-free survival (p = 0.0079). Small interfering RNA (siRNA) knockdown in SK-Hep-1 cells with high endogenous Rsf-1 expression inhibited cell proliferation and colony formation, with downregulation of cyclin E protein. In conclusion, Rsf-1 is overexpressed in HCCs and serves as a novel tumor marker. Rsf-1 contributes to hepatocellular carcinoma cell growth through regulation of cell cycle proteins.

Overexpression of LAPTM4B-35: a novel marker of poor prognosis of prostate cancer

Background

Lysosome-associated protein transmembrane 4b-35 (LAPTM4B-35) is a member of the mammalian 4-tetratransmembrane spanning protein superfamily, which is overexpressed in several solid malignancies. However, the expression of LAPTM4B-35 and its role in the progression of prostate cancer (PCa) is unknown. The aim of the present study was to investigate the LAPTM4B-35 expression in PCa and its potential relevance to clinicopathological variables and prognosis.

Methods

Immunohistochemistry was used to determine the expression of LAPTM4B-35 protein in 180 PCa tissues in comparison with 180 normal benign prostatic hyperplasia (BPH) specimens. The correlation between the expression of the LAPTM4B-35 protein and the clinicopathologic characteristics of patients with PCa was analyzed.

Results

Statistical analysis showed that LAPTM4B-35 expression was significantly elevated in PCa compared with the BPH controls. High LAPTM4B-35 staining was present in 71.11% of all the cases with PCa. The overexpression of LAPTM4B-35 was significantly associated with the lymph node metastasis, seminal vesicle invasion, PCa stage, higher Gleason score, higher preoperative PSA, and biochemical recurrence (BCR). The Kaplan-Meier survival analysis showed that the high expression of LAPTM4B-35 was related to the poor overall survival and BCR-free survival of patients with PCa. Multivariate Cox analysis showed that LAPTM4B-35 was an independent prognostic factor for both overall survival and BCR-free survival of patients with PCa.

Conclusions

Overexpression of LAPTM4B-35 may be associated with tumor progression and poor prognosis in PCa and thus may serve as a new molecular marker to predict the prognosis of PCa patients.

Correlation of LAPTM4B polymorphisms with gallbladder carcinoma susceptibility in Chinese patients

Gallbladder carcinoma (GBC) is a malignancy with an extremely poor prognosis. In order to improve the survival rate, identification of new susceptibility risk factors is of importance. Here, we report findings on the novel cancer-related gene lysosomal protein transmembrane 4 beta (LAPTM4B) that has two alleles designated LAPTM4B*1 and LAPTM4B*2. Allele *1 differs from allele *2 in that it contains one copy of a 19-bp sequence, whereas this sequence is duplicated in exon 1 of allele *2. This study aimed to investigate the relationship of LAPTM4B allelic variation and GBC susceptibility. LAPTM4B genotype was analyzed in 155 healthy individuals and 91 GBC patients by PCR, and the genotypic distribution of LAPTM4B was analyzed with the chi-squared test. The frequency of allele *2 was 37.9 and 24.8% in the GBC and the control groups, respectively, representing a significant difference between these two groups (P<0.001). LAPTM4B allele *2 may be a risk factor associated with genetic susceptibility to GBC.

Expression of SGTA correlates with prognosis and tumor cell proliferation in human hepatocellular carcinoma

To investigate the potential role of small glutamine-rich TPR-containing protein A (SGTA) in hepatocarcinogenesis, immunohistochemistry and Western blot were performed to detect the expression of SGTA in clinical Hepatocellular carcinoma (HCC) samples, adjacent nontumorous liver tissues and HCC cell lines. In addition, expression of SGTA was correlated with clinicopathological variables and univariate and multivariate survival analyses were performed to determine the prognostic significance. Moreover, the biological significance of the aberrant expression of SGTA was investigated in vitro. Both immunohistochemistry evaluation and Western blot analyses demonstrated that SGTA was overexpressed in HCC tissues compared with adjacent nontumorous liver tissues. Expression of SGTA directly correlated with the histological grades of HCC and high expression of SGTA was associated with a poor prognosis. SGTA depletion by siRNA inhibited cell proliferation, blocked S-phase and mitotic entry in Huh7 cells. Western blot analyses showed that SGTA depletion decreased cyclin A and cyclin B levels. Taken together, owing to overexpression of SGTA in HCC and its important role in predicting poor prognosis and the development of HCC, SGTA could be a potential prognostic marker and therapeutic target of HCC.

High SKIP expression is correlated with poor prognosis and cell proliferation of hepatocellular carcinoma

Ski-interacting protein (SKIP) is a transcriptional cofactor distinct from other cofactors and involved in the regulation of many cancer-related proteins. This study investigated the expression of SKIP and its potential clinical and biological significances in hepatocellular carcinoma (HCC). Immunohistochemistry and Western blot were performed to detect the expression of SKIP in clinical HCC samples and adjacent noncancerous tissues. In addition, expression of SKIP was correlated with clinicopathological variables, and univariate and multivariate survival analyses were performed to determine the prognostic significance. Moreover, the biological significance of the aberrant expression of SKIP was investigated in vitro. High SKIP expression was detected in clinical HCC samples compared with adjacent noncancerous tissues. Expression of SKIP correlated directly with the histological grades of HCC and high expression of SKIP was associated with a poor prognosis. SKIP depletion by small interfering RNA inhibited cell proliferation and blocked S phase entry in HepG2 cells. Owing to overexpression of SKIP in HCC tissues and its important role in predicting poor prognosis and the development of HCC, SKIP could be a potential prognostic marker and therapeutic target of HCC.

Hepatocellular tumors: immunohistochemical analyses for classification and prognostication

Following the classification of hepatocellular nodules by the International Working Party in 1995 and further elaboration by the International Consensus Group for Hepatocellular Neoplasia in 2009, entities under the spectrum of hepatocellular nodules have been better characterized. Research work hence has been done to answer questions such as distinguishing high-grade dysplastic nodules from early hepatocellular carcinoma (HCC), delineating the tumor cell origin of HCC, identifying its prognostic markers, and subtyping hepatocellular adenomas. As a result, a copious amount of data at immunohistochemical and molecular levels has emerged. A panel of immunohistochemical markers including glypican-3, heat shock protein 70 and glutamine synthetase has been found to be of use in the diagnosis of small, well differentiated hepatocellular tumors and particularly of HCC. The use of liver fatty acid binding protein (L-FABP), β-catenin, glutamine synthetase, serum amyloid protein and C-reactive protein is found to be helpful in the subtyping of hepatocellular adenomas. The role of tissue biomarkers for prognostication in HCC and the use of biomarkers in subclassifying HCC based on tumor cell origin are also discussed.

LAPTM4B gene polymorphism and endometrial carcinoma risk and prognosis

A novel gene called LAPTM4B (lysosome-associated protein transmembrane 4 beta) plays several crucial roles in carcinogenesis. In this case-control study, we investigated the relationship between LAPTM4B gene polymorphism and susceptibility to endometrial carcinoma (EC). In an adjusted multivariate logistic regression analyses, subjects with the LAPTM4B*1/2 and *2/2 genotypes respectively exhibited 1.572-fold (95% confidence interval (CI) = 1.041-2.375) and 2.335-fold (95% CI = 1.365-3.995) increases in the risk of developing EC relative to those carrying LAPTM4B*1/1. Patients with LAPTM4B *2 had both significantly shorter overall survival (OS) and shorter disease-free survival (DFS) (both p < 0.001). Multivariate analysis showed that LAPTM4B genotype is an independent prognostic factor for OS and DFS (both p < 0.001). These results suggest that LAPTM4B polymorphisms might play an important role in the aetiology of EC.

Overexpression of LAPTM4B: an independent prognostic marker in breast cancer

PURPOSE

Lysosome-associated protein transmembrane 4 beta (LAPTM4B), a novel oncoprotein, has been shown to be overexpressed in several human malignancies. Our purpose was to evaluate the expression of LAPTM4B in breast carcinoma and its significance, which was not previously studied by others.

METHODS

Through immunohistochemistry, LAPTM4B expression was evaluated in 35 benign breast tumor specimens and 194 breast cancer specimens. The correlation of LAPTM4B expression with clinicopathological parameters was assessed using χ(2) analysis. The survival status of patients was analyzed using the Kaplan-Meier and log-rank tests. Cox regression was used for the multivariate analysis of prognostic factors.

RESULTS

The immunohistochemistry results showed that the expression level of LAPTM4B in breast cancer cases was significantly higher than that in benign breast tumor tissues (P < 0.001). Moreover, statistical analysis also showed that high LAPTM4B expression was positively related to TNM stage, lymph node metastasis, and recurrence. Furthermore, it was also shown that patients with high LAPTM4B expression had significantly poorer overall survival and disease-free survival compared with patients with low expression of LAPTM4B (P = 0.019 and P = 0.005, respectively). Multivariate Cox regression analysis revealed that high LAPTM4B expression level was an independent prognostic factor for both overall survival and disease-free survival of patients with breast cancer (P = 0.041 and P = 0.023, respectively).

CONCLUSIONS

Overexpression of LAPTM4B may contribute to the tumor progression and poor prognosis of breast cancer, thus testing the expression of LAPTM4B will be helpful for predicting prognosis in breast cancer.

LAPTM4B overexpression is a novel independent prognostic marker for metastatic ovarian tumors

OBJECTIVE

Metastatic ovarian tumors are a series of lethal carcinomas that almost always have bad prognosis. Their prognoses, however, vary depending on the primary tumor malignancies of each. It has been reported that LAPTM4B, a novel tumor-associated gene, might indicate a worse prognosis when it was overexpressed in other carcinomas. Therefore, the authors expected to investigate whether LAPTM4B overexpression is an independent prognostic marker in metastatic ovarian tumors.

METHODS

Immunohistochemistry was used to assess LAPTM4B expression in metastatic ovarian tumors from 102 patients. Subsequently, univariate and multivariate survival analyses with Cox regression were performed to determine the association between LAPTM4B expression and prognosis. To identify any differences in prognosis between the 2 groups of patients with differing primary malignancies, the log-rank test was used.

RESULTS

The median overall and progression-free survival rates of patients with tumors of gastrointestinal tract origin were 0.97 and 0.51 years, respectively, and both were statistically significantly lower than those of patients with tumors of breast origin (P < 0.0001), which were 2.68 and 1.96 years, accordingly. Of 102 patients, 77 were classified as having a high expression of LAPTM4B, and LAPTM4B expression had a significant association with the prognosis of metastatic ovarian tumors (P < 0.01); no statistically significant interaction between LAPTM4B expression and primary malignancies was detected (P > 0.1). On the other hand, medians of overall survival and progression-free survival of patients with tumors of gastrointestinal tract origin were significantly lower than those of patients with tumors of breast origin (P < 0.0001).

CONCLUSIONS

Patients with metastatic ovarian tumors of breast origin had significantly better prognosis than those with the disease from gastrointestinal tract primary malignancies. LAPTM4B overexpression might be an independent prognostic marker of metastatic ovarian tumors.

LAPTM4B allele *2 is a marker of poor prognosis for gallbladder carcinoma

Background

Lysosomal protein transmembrane 4 beta (LAPTM4B) is a novel cancer-related gene which has two alleles designated LAPTM4B*1 and LAPTM4B*2. In this study we investigated the correlation of LAPTM4B genotype with prognosis and clinicopathologic features in patients who had undergone curative resection for gallbladder carcinoma (GBC).

Methodology/Principal Findings

PCR assay was performed to determine the LAPTM4B genotype in 85 patients. The correlation of LAPTM4B genotype with clinicopathologic parameters was assessed with the Chi-squared test. Differences in patient survival were determined by the Kaplan–Meier method. Multivariate analysis of prognostic factors was carried out with Cox regression analysis. Patients with LAPTM4B *2 had both significantly shorter overall survival (OS) and shorter disease-free survival (DFS) (both P<0.001). Multivariate analysis showed that LAPTM4B genotype is a prognostic factor for OS and DFS (both P<0.001).

Conclusions/Significance

LAPTM4B allele *2 is a risk factor associated with poor prognosis in patients with resected GBC, and LAPTM4B status may be therefore be useful preoperatively as an adjunct in evaluation of the operability of GBC.

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

BACKGROUND

The purpose of this study was to determine whether lysosome-associated protein transmembrane-4 beta (LAPTM4B) overexpression is associated with the prognosis in patients with colorectal cancer.

METHODS

LAPTM4B expression was evaluated in colorectal cancer patients by Western blot analysis and immunohistochemistry. Univariate and multivariate analyses were performed to determine the association between LAPTM4B expression and prognosis.

RESULTS

Among the 136 patients with colorectal cancer, 51 patients had low LAPTM4B expression, and 85 patients had high LAPTM4B expression. The sensitivity and specificity of LAPTM4B overexpression were 62.5% and 100%, respectively. The 5-year overall survival (OS) rates for patients with high and low LAPTM4B expression were 37.38% and 98.04%, respectively (hazard ratio = 22.774; 95% confidence interval [CI], 5.287-98.091; P < .0001). The 5-year disease-free survival rate was 21.15% for patients in the high-expression group and 91.82% for patients in the low-expression group (hazard ratio = 11.674; 95% CI, 3.562-38.263; P < .0001).

CONCLUSIONS

LAPTM4B overexpression is an independent factor in colorectal cancer prognosis, and it may be an important potential biomarker.

LAPTM4B allele *2 is a marker of poor prognosis following hepatic tumor resection for hepatocellular carcinoma

Background

Lysosomal protein transmembrane 4 beta (LAPTM4B) is a gene related to hepatocellular carcinoma that has two alleles designated LAPTM4B*1 and LAPTM4B*2. This study aimed to investigate the correlation of LAPTM4B genotype with prognosis and clinicopathologic features in patients who have undergone resection for hepatocellular carcinoma (HCC).

Methodology/Principal Findings

The LAPTM4B genotype was analyzed by PCR in 68 patients who had undergone curative hepatic resection for hepatocellular carcinoma. The correlation of LAPTM4B genotype with clinicopathologic parameters was assessed with the Chi-squared test. Differences in patient survival were determined by the Kaplan–Meier method. Multivariate analysis of prognostic factors was carried out with Cox regression analysis. Patients with LAPTM4B *2 had both significantly shorter overall survival (OS) and shorter disease-free survival (DFS) (both P<0.001). Multivariate analysis showed that LAPTM4B genotype is an independent prognostic factor for OS and DFS (both P<0.001).

Conclusions/Significance

Allele *2 of LAPTM4B is a risk factor associated with poor prognosis in patients with resected HCC. LAPTM4B status may be useful preoperatively as an adjunct in evaluation of the operability of HCC.

Association of LAPTM4B gene polymorphism with breast cancer susceptibility

BACKGROUND

Lysosome associated protein transmembrane 4 beta (LAPTM4B) was a cancer-associated gene that is mapped to chromosome 8q22 with seven exons and six introns. LAPTM4B gene polymorphism has been reported to be significantly associated with susceptibility of several solid tumors.

METHODS

We performed a case-control study was to investigate the association between LAPTM4B polymorphism and the risk of breast cancer in 732 breast cancer patients and 649 controls.

RESULTS

A significant difference in the frequency of LAPTM4B*2 was observed between the patients and the controls (P < 0.01). Using the LAPTM4B*1/1 genotype as a reference, we found that LAPTM4B allelic variation was significantly associated with breast cancer occurrence, with adjusted odds ratios of 1.387 (95%CI = 1.111-1.730) for LAPTM4B*1/2 and 1.592 (95% CI = 1.043-2.430) for LAPTM4B*2/2 genotype.

CONCLUSION

Our results suggested that LAPTM4B*2 is associated with an increased risk of breast cancer in the Chinese women population and may be a risk factor of breast cancer.

Elevated lysosome-associated protein transmembrane-4β-35 is an independent prognostic marker in pancreatic carcinoma

OBJECTIVES

To investigate the relationship between lysosome-associated protein transmembrane-4β-35 (LAPTM4B-35) and the clinicopathological features and prognosis of pancreatic carcinoma.

METHODS

The level of LAPTM4B-35 protein was determined by semi quantitative immunohistochemistry in pancreatic carcinoma specimens. The relationship between LAPTM4B-35 level and prognosis was determined using univariate and multivariate analyses.

RESULTS

A total of 98 patient samples were included. The presence of LAPTM4B-35 protein was confirmed in 77/98 (78.6%) patients and was significantly associated with tumour stage, degree of differentiation and pathological staging of pancreatic carcinoma after primary surgery. Patients with high LAPTM4B-35 levels had a poorer overall survival compared with patients with lower levels. Multivariate analysis showed that LAPTM4B-35 was an independent prognostic factor for overall survival.

CONCLUSIONS

LAPTM4B-35 was found to be present at high levels in a large proportion of patients with pancreatic carcinoma, and was closely related to disease progression and poor prognosis. LAPTM4B-35 may represent a new molecular target for the clinical evaluation and treatment of pancreatic carcinoma.

Correlation of LAPTM4B polymorphisms with hepatocellular carcinoma in Chinese patients

Hepatocellular carcinoma (HCC) is the leading cause of cancer mortality in many countries. Evaluation of new susceptibility risk factors is therefore warranted in order to explore means to improve the survival rate. Here, we report on a novel HCC-related gene known as lysosomal protein transmembrane 4 beta (LAPTM4B) that has two alleles designated LAPTM4B*1 and LAPTM4B*2. Allele *1 differs from allele *2 in that it contains one copy of a 19-bp sequence, whereas this sequence is duplicated in allele *2 in exon 1 of LAPTM4B. In this study, we aimed to investigate the relationship between LAPTM4B allelic variation and HCC susceptibility. The LAPTM4B genotype was analyzed in the blood samples from 102 HCC patients and 135 healthy individuals by PCR. The genotypic distribution of LAPTM4B was analyzed using the chi-squared test. The frequencies of allele *2 were 38.24 and 24.07% in the HCC group and control group, respectively, representing a significant difference between these two groups (P<0.001). Thus, allele *2 of LAPTM4B appears to be associated with genetic susceptibility of HCC and may therefore be considered as a risk factor.

Relationship between LAPTM4B gene polymorphism and susceptibility of primary liver cancer

BACKGROUND

Lysosome associated protein transmembrane 4 beta (LAPTM4B) was identified first as a novel gene overexpressed in human hepatocellular carcinoma. LAPTM4B*1 and LAPTM4B*2 are two alleles of the gene; they are differentiated at 5'UTR in the first exon. Allele *1 contains only one copy of a 19-bp sequence in the 5'UTR. However, allele *2 contains another identical 19-bp sequence following the first one tightly. In this case-control study, we aimed to identify the relationship between LAPTM4B gene polymorphism and the susceptibility of primary liver cancer.

MATERIALS AND METHODS

The case-control study was conducted in China, including 303 primary liver cancer cases and 515 controls. LAPTM4B gene polymorphism was determined by PCR. Statistical analysis includes odds ratio (OR) and 95% confidence interval (CI) calculations using unconditional logistic regression.

RESULTS

We found a significant difference in the frequency of LAPTM4B*2 between cases and controls (P<0.05). Our study showed that LAPTM4B*1/2 and *2/2 were associated with a significantly increased risk of primary liver cancer compared with LAPTM4B*1/1 (OR=1.898, 95% CI=1.387-2.598 and OR=2.483, 95% CI=1.480-4.168, respectively). The genotypes of LAPTM4B in this study have negative correlation with the clinicopathologicals observed.

CONCLUSION

The evidences suggest that gene polymorphism of LAPTM4B may influence the individuals' susceptibility to primary liver cancer and allele *2 being considered as a potential risk factor.

A role for the ubiquitin ligase Nedd4 in membrane sorting of LAPTM4 proteins

BACKGROUND

The lysosome associated protein transmembrane (LAPTM) family is comprised of three members: LAPTM5, LAPTM4a and LAPTM4b, with the latter previously shown to be overexpressed in numerous cancers. While we had demonstrated earlier the requirement of the E3 ubiquitin ligase Nedd4 for LAPTM5 sorting to lysosomes, the regulation of sorting of LAPTM4 proteins is less clear.

METHODOLOGY/PRINCIPAL FINDINGS

Here we show that LAPTM4a and LAPTM4b are localized to the lysosome, but unique to LAPTM4b, a fraction of it is present at the plasma membrane and its overexpression induces the formation of actin-based membrane protrusions. We demonstrate that LAPTM4s, like LAPTM5, are able to co-immunoprecipitate with the E3 ubiquitin ligase Nedd4, an interaction that is dependent on LAPTM4 PY motifs and plays a role in membrane sorting. Accordingly, in Nedd4 knockout mouse embryonic fibroblasts (MEFs), LAPTM4a and LAPTM4b show reduced lysosomal localization. Moreover, lack of PY motifs leads to enhanced missorting of LAPTM4b to the plasma membrane instead of the lysosome.

CONCLUSIONS/SIGNIFICANCE

These results suggest that while some requisites of LAPTM5 lysosomal sorting are conserved among LAPTM4 proteins, LAPTM4a and LAPTM4b have also developed distinct sorting requirements.

Lysosomal transmembrane protein LAPTM4B promotes autophagy and tolerance to metabolic stress in cancer cells

Amplification of chromosome 8q22, which includes the gene for lysosomal associated transmembrane protein LAPTM4B, has been linked to de novo anthracycline resistance in primary breast cancers with poor prognosis. LAPTM4B overexpression can induce cytosolic retention of anthracyclines and decrease drug-induced DNA damage. In this study, we tested the hypothesis that LAPTM4B may contribute to tumor cell growth or survival in the absence of a chemotherapeutic exposure. In mammary cells, LAPTM4B protein was localized in lysosomes where its depletion increased membrane permeability, pH, cathepsin release, and cellular apoptosis. Loss of LAPTM4B also inhibited later stages of autophagy by blocking maturation of the autophagosome, thereby rendering cells more sensitive to nutrient deprivation or hypoxia. Conversely, enforced overexpression of LAPTM4B promoted autophagic flux and cell survival during in vitro starvation and stimulated more rapid tumor growth in vivo. Together, our results indicate that LAPTM4B is required for lysosome homeostasis, acidification, and function, and that LAPTM4B renders tumor cells resistant to lysosome-mediated cell death triggered by environmental and genotoxic stresses.

Combined lysosomal protein transmembrane 4 beta-35 and argininosuccinate synthetase expression predicts clinical outcome in hepatocellular carcinoma patients

PURPOSE

The newly-identified lysosomal protein transmembrane 4 beta-35 (LAPTM4B-35) plays important roles in tumor progression and metastasis, while argininosuccinate synthetase (ASS) provides arginine as an indispensable nutrient for hepatocellular carcinoma (HCC). The present study investigated the clinical significance of the coexpression of LAPTM4B-35 and ASS in HCC patients on determining the prognosis.

METHODS

Immunohistochemistry was used to evaluate the expression of LAPTM4B-35 and ASS in HCC tissues and paired noncancerous liver samples from 71 patients. The correlation of combined LAPTM4B-35 and ASS expression with selected clinicopathologic parameters was assessed with the chi-squared test. Patient survival and differences in survival were determined by the Kaplan-Meier method and the log-rank test. A Cox regression analysis was adopted for a multivariate analysis of the prognostic factors.

RESULTS

Combined LAPTM4B-35 and ASS expression was significantly associated with TNM stage and portal vein invasion. In addition, patients with HCCs expressing both LAPTM4B-35 and ASS exhibited both markedly poorer overall survival (OS) and disease-free survival (DFS) (both P < 0.001). According to the multivariate analyses, combined LAPTM4B-35 and ASS expression was found to be an independent prognostic factor for OS and DFS (P = 0.039 and P = 0.035, respectively).

CONCLUSION

The overexpression of LAPTM4B-35 in combination with positive ASS expression is a negative prognostic marker for HCC.

Upregulation of LAPTM4B-35 promotes malignant transformation and tumorigenesis in L02 human liver cell line

Hepatocellular carcinoma (HCC) is one of the most frequent malignant neoplasms worldwide and is the second leading cause of cancer death in China. We have previously demonstrated that LAPTM4B-35, encoded by lysosomal protein transmembrane 4 beta gene, is overexpressed in over 80% of HCCs and is a novel-independent prognostic factor for metastasis, recurrence, and postoperative survival in HCC. In this study, we investigated the role of LAPTM4B-35 in malignant transformation and tumorigenesis using L02 cells, a cell line originated from human normal liver cells. Our data show that replication-deficient adenovirus vector-mediated upregulation of LAPTM4B-35 promotes anchorage-independent proliferation and resistance to adriamycin-induced apoptosis. Study of the underlying mechanisms demonstrated alterations of molecular events involved in these processes, which included the activation of phosphoinositide 3-kinases (PI3K)/serine/threonine protein kinase B (PKB/AKT)/bcl-xL/bcl-2-associated death promoter homolog (Bad) signaling pathway, inhibition of caspase-3 activation, upregulation of Bcl-2, and downregulation of Bax. In addition, upregulation of LAPTM4B-35 in L02 cells resulted in tumorigenesis in 100% (6/6) of inoculated nude mice and accelerated the death of mice with xenografts in vivo. In conclusion, LAPTM4B-35 promotes malignant transformation and tumorigenesis in human liver L02 cell line through promotion of deregulated proliferation and inhibition of apoptosis. These findings suggest that overexpression of LAPTM4B-35 may play a critical role in hepatocarcinogenesis and therefore, may be a therapeutic target for HCC.

Over-expression of LAPTM4B is associated with poor prognosis and chemotherapy resistance in stages III and IV epithelial ovarian cancer

BACKGROUND

The purpose of this study was to determine whether LAPTM4B over-expression is associated with the prognosis and chemotherapy resistance in patients with stages III and IV epithelial ovarian carcinoma, i.e., patients with peritoneal metastasis or lymph node metastasis of epithelial ovarian carcinoma.

METHODS

LAPTM4B expression was evaluated in 10 normal ovarian and 113 stages III-IV ovarian carcinomas specimens by Western blotting analyses and immunohistochemistry. Univariate and multivariate analyses were performed to determine the association between LAPTM4B expression and prognosis and the relationship between LAPTM4B over-expression and chemotherapy resistance.

RESULTS

Western blotting analysis demonstrated that LAPTM4B was overexpressed in ovarian cancers, and immunohistochemistry results revealed that 80 patients were LAPTM4B over-expression. The five-year overall survival (OS) rates for patients with high LAPTM4B expression and low LAPTM4B expression were 27.36% and 90.7%, respectively (hazard ratio = 20.611, 95% CI: 5.916-71.808, P < 0.0001). The five-year progression-free survival (PFS) rate was 17.68% for patients in the high-expression group and 84.42% for patients in the low-expression group (hazard ratio = 17.852, 95% CI: 6.31-5.935, P < 0.0001); The presence of chemotherapy resistance was significantly associated with LAPTM4B expression (OR: 36.609, 95% CI: 4.737-282.941, P = 0.0006).

CONCLUSIONS

LAPTM4B over-expression is an independent factor in stages III-IV epithelial ovarian carcinoma prognosis and chemotherapy resistance, and it may be an important potential biomarker.

LAPTMs regulate lysosomal function and interact with mucolipin 1: new clues for understanding mucolipidosis type IV

Loss-of-function mutations in mucolipin 1 (MCOLN1) result in mucolipidosis type IV (MLIV), a lysosomal storage disorder characterized by severe mental and psychomotor retardation. MCOLN1 is a lysosomal ion channel that belongs to the transient receptor potential (TRP) superfamily. To better understand the cellular function of MCOLN1, a split-ubiquitin yeast two-hybrid screen was performed with the purpose of revealing new MCOLN1 interaction partners. The screen identified two members of the lysosome-associated protein transmembrane (LAPTM) family as novel interaction partners of MCOLN1. The binding between MCOLN1 and LAPTM members (LAPTMs) was confirmed by co-immunoprecipitation and yeast two-hybrid assays. In addition, MCOLN1 and LAPTMs extensively colocalize at late endosomes and lysosomes. Overexpression of LAPTM4b caused enlargement of lysosomes and defective lysosomal degradation, indicating that LAPTMs are important for proper lysosomal function. Interestingly, lysosomal swelling induced by LAPTM4b was rescued by expression of MCOLN1, suggesting a functional connection between the two proteins. Finally, depletion of endogenous LAPTMs by siRNA induced accumulation of concentric multi-lamellar structures and electron-dense inclusions that closely resemble the structures found in MLIV cells. Overall, our data provide new insight into the molecular mechanisms of MCOLN1 function and suggest a potential role for LAPTMs in MLIV pathogenesis.