Structure analysis and expressions of a novel tetratransmembrane protein, lysosoma-associated protein transmembrane 4 β associated with hepatocellular carcinoma

A comprehensive analysis of the prognostic value and immune microenvironment of lysosome-dependent cell death in glioma: Including glioblastoma and low-grade glioma

Lysosome-dependent cell death (LCD) plays a significant role in overcoming cancer apoptosis and drug resistance. However, the relationship between LCD-associated genes (LCDGs) and glioma, including glioblastoma (GBM) and low-grade glioma (LGG), remains unclear. In this study, an LCDGs risk signature was constructed for glioma patients by utilizing 4 algorithms (Extreme Gradient Boosting, Support Vector Machine, Random Forest, and Generalized Linear Models) to identify core LCDGs. Their correlation with clinical features and the immune microenvironment was also determined in glioma, GBM, and LGG. Additionally, the role of hub LCDGs in various cancers was elucidated via pan-cancer analyses. Validation of the core gene in glioma was performed using qRT-qPCR and immunofluorescence staining analysis. The results showed that the LCDGs risk signature was strongly associated with the prognosis, cancer grades, histological types, and primary therapy outcomes of glioma patients. Furthermore, it was closely linked to the overall survival of LGG patients. Mechanistic analyses revealed a significant association between the risk signature and the immune microenvironment in glioma. Based on differential expression analysis, receiver operating characteristic analysis, and interacted model algorithms, LAPTM4A was identified as a hub LCDG in glioma. It exhibited significant upregulation in glioma, GBM, and LGG samples. Moreover, LAPTM4A expression correlated with the prognosis of glioma and LGG patients, as well as age, grades, histological types, and primary therapy outcomes in glioma. Pan-cancer analysis confirmed that LAPTM4A expression was modulated in the majority of cancers and was associated with the prognosis of various cancers. Mechanistic analyses suggested a strong relationship between LAPTM4A and immune cell infiltration, as well as several drug sensitivities. In conclusion, our findings suggest that LAPTM4A may serve as a potential oncogene associated with LCD in pan-cancer, particularly in glioma, GBM, and LGG. These findings provide important insights for individualized treatment of glioma.

In vitro modelling of the physiological and diseased female reproductive system

The maladies affecting the female reproductive tract (FRT) range from infections to endometriosis to carcinomas. In vitro models of the FRT play an increasingly important role in both basic and translational research, since the anatomy and physiology of the FRT of humans and other primates differ significantly from most of the commonly used animal models, including rodents. Using organoid culture to study the FRT has overcome the longstanding hurdle of maintaining epithelial phenotype in culture.  Both ECM-derived and engineered materials have proved critical for maintaining a physiological phenotype of FRT cells in vitro by providing the requisite 3D environment, ligands, and architecture. Advanced materials have also enabled the systematic study of factors contributing to the invasive metastatic processes. Meanwhile, microphysiological devices make it possible to incorporate physical signals such as flow and cyclic exposure to hormones. Going forward, advanced materials compatible with hormones and optimised to support FRT-derived cells' long-term growth, will play a key role in addressing the diverse array of FRT pathologies and lead to impactful new treatments that support the improvement of women's health. STATEMENT OF SIGNIFICANCE: The female reproductive system is a crucial component of the female anatomy. In addition to enabling reproduction, it has wide ranging influence on tissues throughout the body via endocrine signalling. This intrinsic role in regulating normal female biology makes it susceptible to a variety of female-specific diseases. However, the complexity and human-specific features of the reproductive system make it challenging to study. This has spurred the development of human-relevant in vitro models for helping to decipher the complex issues that can affect the reproductive system, including endometriosis, infection, and cancer. In this Review, we cover the current state of in vitro models for studying the female reproductive system, and the key role biomaterials play in enabling their development.

LAPTM4B promotes the progression of nasopharyngeal cancer

Lysosomal protein transmembrane 4 beta (LAPTM4B) is a protein that contains four transmembrane domains. The impact of LAPTM4B on the malignancy of nasopharyngeal carcinoma (NPC) remains unclear. In the present study, we aimed to investigate the role of LAPTM4B in NPC. NPC tissue samples were used to evaluate the expression of LAPTM4B and its relationship with patient prognosis. Furthermore, we inhibited the expression of LAPTM4B in NPC cell lines and examined the effects of LAPTM4B on NPC cell proliferation, migration, and invasion. We found that LAPTM4B protein was mainly localized in the cytoplasm and intracellular membranes of NPC cells. LAPTM4B protein was upregulated in NPC tissues and cell lines. High LAPTM4B expression was closely related to pathological subtypes and disease stages in NPC patients. NPC patients with high LAPTM4B expression had a worse prognosis. LAPTM4B knockdown inhibited the proliferation, migration, and invasion ability of NPC cells. LAPTM4B plays a cancer-promoting role in the progression of NPC and may be a potential target for NPC therapy.

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.

Helicobacter pylori infection promotes epithelial-to-mesenchymal transition of gastric cells by upregulating LAPTM4B

Helicobacter pylori infection can lead to epithelial-to-mesenchymal transition (EMT) and the progression of gastric cancer (GC); however, the underlying mechanism is poorly understood. Lysosomal-associated protein transmembrane 4β (LAPTM4B) has been implicated in carcinogenesis, including in GC, and we previously showed that LAPTM4B-35 overexpression was an independent prognostic factor in GC. In this study, we demonstrate that upregulation of LAPTM4B promotes GES-1 human gastric epithelial cell proliferation, migration, and invasion and EMT. Conversely, LAPTM4B downregulation inhibited proliferation, migration, invasion, and EMT in SGC7901 GC cells. We also found that H. pylori infection enhanced LAPTM4B expression and induced EMT in GES-1 cells. Thus, EMT in GC is promoted by a combination of LAPTM4B overexpression and H. pylori infection. These results provide a basis for the development of novel two-pronged therapeutic strategies for the treatment of GC.

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.

Increased levels of LAPTM4B, VEGF and survivin are correlated with tumor progression and poor prognosis in breast cancer patients

Objective

This study explored the relationships among the expression of LAPTM4B, VEGF, and survivin and clinicopathological characteristics and prognosis in breast cancer patients.

Methods

The expression of these three molecules in 110 stage I-III breast cancer patients with clinicopathological and follow-up data was detected via immunohistochemistry. Kaplan-Meier and Cox proportional hazard regression analyses were performed to assess the prognostic significance of these markers in breast cancer. Moreover, expression levels of these markers were evaluated in 5 breast cell lines via Western blot analysis.

Results

LAPTM4B, VEGF, and survivin were over-expressed in breast cancer specimens and highly expressed in MDA-MB-231 cells. VEGF and nuclear survivin expression was significantly correlated with LAPTM4B expression, and high levels of all three were associated with a tumor size >2cm, TNM stage II+III and lymph node metastasis, which had worse impacts on overall survival and progression-free survival in breast cancer patients. A multivariate Cox analysis identified LAPTM4B over-expression as an independent prognostic marker in breast cancer.

Conclusions

These findings suggest that LAPTM4B, VEGF, and nuclear survivin expression are significantly correlated in breast cancer, which may be predictive of prognosis as well as effective therapeutic targets for new anticancer therapies.

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.

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.

Association between LAPTM4B gene polymorphism and susceptibility to and prognosis of diffuse large B-cell lymphoma

Lysosomal protein transmembrane 4β (LAPTM4B) is an oncogene that is overexpressed in a number of various types of human cancer. There are two known alleles of LAPTM4B: LAPTM4B*1 and LAPTM4B*2. The present study assessed the association between LAPTM4B polymorphisms and the susceptibility to diffuse large B-cell lymphoma (DLBCL) and its prognosis. LAPTM4B genotypes were determined using polymerase chain reaction analysis in 164 DLBCL and 350 healthy control cases. The association between LAPTM4B polymorphisms and the risk of DLBCL was analyzed using unconditional logistic regression. Differences in patient survival were calculated using Kaplan-Meier analysis. The present study indicated no significant differences (P>0.05) in the frequency of LAPTM4B*2 alleles between DLBCL cases (26.5%) and controls (24.1%). The risk of DLBCL was slightly increased in cases with the LAPTM4B*1/2 genotype [odds ratio (OR)=1.160; 95% confidence interval (CI)=0.781–1.724] or the LAPTM4B*2/2 genotype (OR=1.446; 95% CI=0.648–3.227) compared with those with the LAPTM4B*1/1 genotype. There was no significant association between the presence of the LAPTM4B*2 allele and overall survival (OS) and disease-free survival (DFS) in patients with DLBCL (P=0.399 and 0.520, respectively). However, there was a tendency for patients with LAPTM4B*2 and International Prognostic Index (IPI) score 3–5 to have longer OS and DFS (P=0.126 and 0.109, respectively). These findings suggest that genetic polymorphisms of LAPTM4B is not a risk factor for the development of DLBCL, but the LAPTM4B*2 allele may a better prognostic indicator in patients with IPI score 3–5 in DLBCL.

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.

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.

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.

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.

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.

A kinase-independent role for EGF receptor in autophagy initiation

The epidermal growth factor receptor (EGFR) is upregulated in numerous human cancers. Inhibition of EGFR signaling induces autophagy in tumor cells. Here, we report an unanticipated role for the inactive EGFR in autophagy initiation. Inactive EGFR interacts with the oncoprotein LAPTM4B that is required for the endosomal accumulation of EGFR upon serum starvation. Inactive EGFR and LAPTM4B stabilize each other at endosomes and recruit the exocyst subcomplex containing Sec5. We show that inactive EGFR, LAPTM4B, and the Sec5 subcomplex are required for basal and starvation-induced autophagy. LAPTM4B and Sec5 promote EGFR association with the autophagy inhibitor Rubicon, which in turn disassociates Beclin 1 from Rubicon to initiate autophagy. Thus, the oncoprotein LAPTM4B facilitates the role of inactive EGFR in autophagy initiation. This pathway is positioned to control tumor metabolism and promote tumor cell survival upon serum deprivation or metabolic stress.

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.

Differential expression of lysosome-associated protein transmembrane-4 beta (LAPTM4B) in granulosa cells of ovarian follicles and in other bovine tissues

Background

LAPTM4B is a member of the lysosome-associated transmembrane protein superfamily that is differentially expressed in normal human tissues and upregulated in various types of carcinomas. These proteins are thought to be involved in the regulation of cell proliferation and survival. The objective of this study was to investigate the expression of bovine LAPTM4B during ovarian follicular development and in various bovine tissues.

Methods and results

Northern blot analysis revealed a 1.8 kb transcript, with highly variable steady state levels among tissues. RT-PCR analysis showed that LAPTM4B mRNA transcripts were low in granulosa cells of small antral follicles, increased in large dominant follicles, and decreased in ovulatory follicles following injection of human chorionic gonadotropin (hCG; P < 0.003). Ovulatory follicles collected at various times after hCG injection revealed a significant reduction of LAPTM4B mRNA starting at 18 h post-hCG (P < 0.029). Immunobloting analysis using antibodies generated against bovine LAPTM4B recognized proteins of 26.3 and 31.5 kDa in granulosa cells of developing follicles and corpus luteum. Further analyses of affinity-purified His-tag LAPTM4B overexpressed in HEK cells showed that the 31.5 kDa protein represented the ubiquinated isoform of the 26.3 kDa native protein. The 26.3 kDa protein was differentially expressed showing highest amounts in dominant follicles and lowest amounts in ovulatory follicles 24 h post-hCG. Immunohistochemical analyses of LAPTM4B showed marked heterogeneity of labeling signal among tissues, with LAPTM4B mainly localized to perinuclear vesicles, in keeping with its putative lysosomal membrane localization.

Conclusion

This study reports for the first time that bovine LAPTM4B in granulosa cells is present in both unubiquinated and ubiquinated forms, and is differentially expressed in developing ovarian follicles, suggesting a possible role in terminal follicular growth.

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.

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.

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.

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 polymorphisms is associated with ovarian cancer susceptibility and its prognosis

OBJECTIVE

Lysosome-associated protein transmembrane 4 beta (LAPTM4B) is an important novel gene associated with the proliferation and differentiation of cells. Recent studies have shown that it was overexpressed in many cancer tissues. This study investigated the association between different LAPTM4B polymorphisms and the susceptibility and prognosis of ovarian cancer.

METHODS

A case-control study was performed in 282 patients with ovarian cancer and 365 control subjects. Genomic DNA was extracted from peripheral blood lymphocytes in all participants. LAPTM4B genotypes were determined using polymerase chain reaction.

RESULTS

There was a significantly higher LAPTM4B 2 allele frequency in ovarian cancer cases than controls (P < 0.05). Using the LAPTM4B 1/1 genotype as the reference, we found that the LAPTM4B 1/2 and LAPTM4B 2/2 genotypes were positively associated with ovarian cancer. Additionally, we found a negative correlation between the tumor grade and LAPTM4B allele genotype, which indicates strongly that LAPTM4B 2 could affect the survival of patients.

CONCLUSIONS

These findings indicate that the LAPTM4B 2 allele may be a risk factor for ovarian cancer and may play an important role in genetic susceptibility to ovarian cancer.

Cyclic interconversion of methionine containing peptide between oxidized and reduced phases monitored by reversed-phase HPLC and ESI-MS/MS

The cyclic oxidation and reduction of methionine (Met) containing peptides and proteins play important roles in biological system. This work was contributed to analysis the cyclic oxidation and reduction processes of a methionine containing peptide which is very likely to relate in the cell signal transduction pathways. To mimic the biological oxidation condition, hydrogen peroxide was used as the reactive oxygen species to oxidize the peptide. Reversed-phase high-performance liquid chromatography and mass spectrometry were employed to monitor the reactions and characterize the structural changes of the products. A rapid reduction procedure was developed by simply using KI as the reductant, which is green and highly efficient. By investigation of the cyclic oxidation and reduction process, our work provides a new perspective to study the function and mechanism of Met containing peptides and proteins during cell signaling processes as well as diseases.

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.

Overexpression of LAPTM4B-35 attenuates epirubucin-induced apoptosis of gallbladder carcinoma GBC-SD cells

BACKGROUND

It was shown previously that LAPTM4B promoted growth of gallbladder carcinoma (GBC) cells and predicted poor prognosis in GBC; however, its roles and relative mechanisms in apoptosis of GBC cells remain unknown.

METHODS

The plasmids, pcDNA3-AE, containing the complete open reading frame of LAPTM4B and Mock (pcDNA3), were transfected transiently into GBC-SD cells, followed by induction of apoptosis by epirubicin. Cell apoptosis was determined by Hoechst 33258 staining, propidium iodide (PI) staining, and Annexin V/PI double staining flow cytometry. Protein expression was detected by immunoblotting.

RESULTS

Overexpression of LAPTM4B-35 was observed in cells transfected with pcDNA3-AE. These cells possessed significantly less apoptosis ratios compared with cells transfected with the Mock plasmid, although the values were still greater than those in parent cells. Of the apoptosis-related molecules, expression of Bcl-2 and Bcl-xL was up-regulated in cells transfected with pcDNA3-AE, whereas expressions of Bax, Bid, and cleaved caspase-9 and -3 were down-regulated compared with their expression in other kinds of cells.

CONCLUSION

Our data show that LAPTM4B-35 attenuated epirubicin-induced apoptosis of GBC-SD cells in vitro through a mitochondria-dependent pathway. Therefore, the protein LAPTM4B-35 might be associated with the chemoresistance of GBC.

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.

LAPTM4B-35 overexpression is an independent prognostic marker in endometrial carcinoma

BACKGROUND

Lysosomal protein transmembrane 4 β-35 (LAPTM4B-35), a novel oncoprotein that belongs to the mammalian 4-tetratransmembrane spanning protein superfamily, has been implicated in oncogenesis and cancer progression in several solid malignances. However, the expression of LAPTM4B-35 and its role in endometrial cancer progression remain unknown.

MATERIALS AND METHODS

We investigated the expression of the LAPTM4B-35 protein by immunohistochemistry in 30 normal endometrium specimens and 165 endometrial carcinomas and analyzed its correlation with various clinicopathologic features, including patient outcome.

RESULTS

LAPTM4B-35 immunoreactivity was overexpressed in endometrial carcinoma cases compared with normal endometrium (P < 0.001). High LAPTM4B-35 expression was found in 117 (70.91%) of these 165 carcinomas and was positively correlated with the International Federation of Gynecology and Obstetrics stage, histological grade, depth of myometrial invasion, lymph node metastasis, lymph vascular space involvement, and recurrence, but not with age and histological type. Patients with high LAPTM4B-35 expression had significantly poorer overall survival and disease-free survival compared with patients with low expression of LAPTM4B-35 (P = 0.001 and P = 0.002, respectively). Multivariate analysis showed that high LAPTM4B-35 expression was an independent prognostic factor for both overall survival and disease-free survival of patients with endometrial carcinoma (both P = 0.005).

CONCLUSIONS

These results showed that high LAPTM4B-35 expression was associated with progression and prognosis of endometrial carcinoma.

Downstream targets of HOXB4 in a cell line model of primitive hematopoietic progenitor cells

Enforced expression of the homeobox transcription factor HOXB4 has been shown to enhance hematopoietic stem cell self-renewal and expansion ex vivo and in vivo. To investigate the downstream targets of HOXB4 in hematopoietic progenitor cells, HOXB4 was constitutively overexpressed in the primitive hematopoietic progenitor cell line EML. Two genome-wide analytical techniques were used: RNA expression profiling using microarrays and chromatin immunoprecipitation (ChIP)-chip. RNA expression profiling revealed that 465 gene transcripts were differentially expressed in KLS (c-Kit(+), Lin(-), Sca-1(+))-EML cells that overexpressed HOXB4 (KLS-EML-HOXB4) compared with control KLS-EML cells that were transduced with vector alone. In particular, erythroid-specific gene transcripts were observed to be highly down-regulated in KLS-EML-HOXB4 cells. ChIP-chip analysis revealed that the promoter region for 1910 genes, such as CD34, Sox4, and B220, were occupied by HOXB4 in KLS-EML-HOXB4 cells. Side-by-side comparison of the ChIP-chip and RNA expression profiling datasets provided correlative information and identified Gp49a and Laptm4b as candidate "stemness-related" genes. Both genes were highly ranked in both dataset lists and have been previously shown to be preferentially expressed in hematopoietic stem cells and down-regulated in mature hematopoietic cells, thus making them attractive candidates for future functional studies in hematopoietic cells.

Overexpression of LAPTM4B promotes growth of gallbladder carcinoma cells in vitro

BACKGROUND

The overexpression of LAPTM4B-35 in gallbladder carcinoma (GBC) and its clinicopathologic and prognostic significance have been previously shown. Thus, this gene may play a role in the growth of GBC cells.

METHODS

The pcDNA3-AE containing the complete open reading frame of LAPTM4B (lysosome-associated protein transmembrane-4beta) and mock (pcDNA3) plasmids were transiently transfected into GBC-SD cells. Cell proliferation, cell cycle distribution, and protein expression were evaluated by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium assay, flow cytometry, and Western blot, respectively.

RESULTS

Cells transfected with pcDNA3-AE revealed accelerated proliferation, less serum dependence, and significant cell cycle progression compared with cells transfected with mock plasmid and parent cells. These phenotypes were accompanied by upregulated expression of C-myc, c-Fos, c-Jun, cyclin D1, and cyclin E and downregulated expression of P16 and P-27.

CONCLUSIONS

LAPTM4B overexpression promotes the growth of GBC cells in vitro by regulating the expression levels of some proliferation-associated proteins. Therefore, the LAPTM4B gene might be used as a novel therapeutic target of GBC.

LAPTM4B-35, a novel tetratransmembrane protein and its PPRP motif play critical roles in proliferation and metastatic potential of hepatocellular carcinoma cells

Lysosomal protein transmembrane 4 beta (LAPTM4B) was originally identified as a hepatocellular carcinoma (HCC)-associated gene. This gene and its protein product LAPTM4B-35, are both overexpressed in a variety of human cancers. However, its specific role in cell transformation and malignancy has remained elusive. In the present study we investigated the effects of LAPTM4B-35 overexpression on the malignant phenotypic features in the HLE cell line. Our data show that overexpression of LAPTM4B-35 promotes cell proliferation, exogenous growth-stimulating factor-independent and anchorage-independent growth, and enhances metastatic potential, including promotion of both cell migration and invasion. Study of the underlying mechanisms demonstrated alterations of molecular events involved in these processes, which included upregulation of proliferation-promoting transcription factors such as c-Myc, c-Jun, and c-Fos, and cell cycle-promoting proteins such as cyclin D1 and cyclin E. In addition, mutagenesis study showed that the PPRP motif in the N-terminal region of LAPTM4B-35 plays a critical role in promoting proliferation, migration, and invasion, as well as in the upregulation of the oncoproteins noted above. These data offer insight into the mechanism by which this novel tetratransmembrane protein contributes to the pathogenesis of liver cancer, and suggest that it may be a potential target for cancer therapy.

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

PURPOSE

Lysosomal protein transmembrane 4 beta-35 (LAPTM4B-35) is a tetra-transmembrane glycoprotein that is abundantly localized on membrane-bound organelles including endosomes and lysosomes, and promotes cell proliferation and tumorigenesis through regulation of cell cycle and signaling pathways. The aim of the present study is to determine the potential clinical implications of LAPTM4B-35 expression in hepatocellular carcinoma (HCC).

METHODS

Immunohistochemistry assay was used to determine the expression of LAPTM4B-35 protein in normal and HCC tissues from 71 patients. The correlations of LAPTM4B-35 expression with clinicopathological parameters, including gender, age, background liver, viral status, tumor size, portal vein invasion, histopathological differentiation, serum AFP level, TNM staging and recurrence of HCC were assessed by Chi-squared test. Patient survival and their differences were determined by Kaplan-Meier method and log-rank test. Cox regression (Proportional hazard model) was adopted for multivariate analysis of prognostic factors.

RESULTS

LAPTM4B-35 immunoreactivity was negative or low in normal liver tissues, but high in HCC tissues (51/71, 71.8%). The overexpression of LAPTM4B-35 was significantly associated with recurrence, TNM staging and portal vein invasion of HCC. Patients with high LAPTM4B-35 expression had significantly poorer overall survival (OS) and disease-free survival (DFS) (both P < 0.001) when compared with patients with the low expression of LAPTM4B-35. On multivariate analysis, LAPTM4B-35 expression was found to be an independent prognostic factor for OS and DFS (P = 0.018 and P = 0.001, respectively).

CONCLUSION

LAPTM4B-35 expression showed a strong association with the potencies of recurrence and metastasis and progression of HCC, and that may be applied as a novel marker for the prediction of recurrence and metastasis potency of HCC, and helpful for improving the diagnosis, prognosis and treatment of HCC.

Expression of LAPTM4B-35: a novel marker of progression, invasiveness and poor prognosis of extrahepatic cholangiocarcinoma

LAPTM4B was proven to overexpress in hepatocellular carcinoma and relate to differentiation. We immunohistochemically investigated the expression and potential clinicopathological and prognostic significance of LAPTM4B encoded protein, LAPTM4B-35, in extrahepatic cholangiocarcinoma (EHCC) for specimens from consecutive 81 patients. LAPTM4B-35 staining was positive in cancer tissues from 59 patients (72.8%), including 12 with score 1, 22 with score 2 and 25 with score 3. No positive staining was found in non-cancer epithelia. The staining score in cancer tissues was not only significantly associated with TNM staging, histological grade, perineural and lymph node invasion (P<0.05), but also of comprehensive prognostic implications, including integrated estimation with CA19-9. These data established that LAPTM4B-35 positively expressed in a great portion of EHCC and might be a novel molecular maker of progression, invasiveness and poor prognosis.

Relationship between LAPTM4B gene polymorphism and susceptibility of colorectal and esophageal cancers

BACKGROUND

Lysosome-associated protein transmembrane 4 beta (LAPTM4B) is a novel gene of the mammalian LAPTM family and has been shown to be overexpressed in human hepatocellular carcinoma. There are two alleles, LAPTM4B*1 and *2, which share the same sequence except for one segment of 19 bp in the 5' untranslated region of the exon 1. LAPTM4B*1 has one 19 bp segment, while LAPTM4B*2 has two tight tandem segments. The current case-control study was aimed to identify relationship between the gene polymorphism of LAPTM4B and the susceptibility of colorectal and esophageal cancers.

PATIENTS AND METHODS

Blood samples were collected from patients with colon, rectal or esophageal cancers and control subjects. Genotypes of LAPTM4B were determined by PCR to detect differences between cancer cases (n = 701) and healthy controls (n = 350). Association between the LAPTM4B polymorphism and the risk of cancer was calculated by unconditional logistic regression models.

RESULTS

We found that there was a significant difference (P = 0.0016) in allelic frequencies of LAPTM4B*2 between colon cancer cases (33.2%) and controls (24.1%). The risk of colon cancer was elevated significantly in cases with *1/2 genotype [odds ratio (OR) = 1.474; 95% confidence interval (CI) = 1.037-2.095] and *2/2 genotype (OR = 2.531; 95% CI = 1.316-4.868) when compared with the *1/1 genotype. No significant difference was observed for LAPTM4B*2 between the rectal or esophageal cancer cases when compared with the controls. The polymorphism in LAPTM4B was associated with increased risk of colon cancer but not of rectal and esophageal cancers.

CONCLUSIONS

These results indicate that the genetic polymorphism of LAPTM4B is a potential risk factor for the development of colon cancer.

Overexpression of LAPTM4B-35 closely correlated with clinicopathological features and post-resectional survival of gallbladder carcinoma

Gallbladder carcinoma (GBC) is a malignancy with dismal prognosis and unclear gene expression profile. We aimed to first present the expression of LAPTM4B-35, one product of a cancer associated gene recently cloned in hepatocellular carcinoma (HCC), and its correlation with clinicopathological features and prognosis of GBC. Immunohistochemical detection of LAPTM4B-35 was performed on samples from 75 patients with GBC. LAPTM4B-35 protein was overexpressed in 57 patients (76%) with GBC. The staining scores were significantly related to histology type, lymph node involvement, distant metastasis, Nevin staging and differentiation of GBC (P<0.05). Univariate analysis revealed that overall or disease-free survival of patients was inversely associated with its staining scores (P<0.001). Multivariate analysis showed that LAPTM4B-35 staining score was an independent prognostic marker for both overall and disease-free post-resectional survival of GBC (P=0.004 and 0.027, respectively). LAPTM4B-35 overexpressed in a majority of GBCs and correlated with clinicopathological features and post-resectional survival.

Gene expression alterations in activated human T-cells induced by modeled microgravity

Studies conducted in real Space and in ground-based microgravity analog systems (MAS) have demonstrated changes in numerous lymphocyte functions. In this investigation we explored whether the observed functional changes in lymphocytes in MAS are associated with changes in gene expression. NASA-developed Rotating Wall Vessel (RWV) bioreactor was utilized as a MAS. Activated T lymphocytes were obtained by adding 100 ng/ml of anti-CD3 and 100 U/ml of IL-2 in RPMI medium to blood donor mononuclear cells for 4 days. After that the cells were washed and additionally cultured for up to 2 weeks with media (RPMI, 10% FBS and 100 U/ml IL-2) replacement every 3-4 days. Flow cytometry analysis had proven that activated T lymphocytes were the only cells remaining in culture by that time. They were split into two portions, cultured for additional 24 h in either static or simulated microgravity conditions, and used for RNA extraction. The gene expression was assessed by Affymetrix GeneChip Human U133A array allowing screening for expression of 18,400 genes. About 4-8% of tested genes responded to MG by more than a 1.5-fold change in expression; however, reproducible changes were observed only in 89 genes. Ten of these genes were upregulated and 79 were downregulated. These genes were categorized by associated pathways and viewed graphically through histogram analysis. Separate histograms of each pathway were then constructed representing individual gene expression fold changes. Possible functional consequences of the identified reproducible gene expression changes are discussed.

Relationship between LAPTM4B gene polymorphism and susceptibility of gastric cancer

BACKGROUND

A novel gene called LAPTM4B (lysosome-associated protein transmembrane 4beta) was mapped to 8q22, and contains seven exons. The 2.25-kb messenger RNA of the gene encodes a putative lysosome-associated protein with four transmembrane regions. There are two alleles of the gene, named as LAPTM4B*1 and LAPTM4B*2. Allele *1 differs from allele *2 in that it contains only one copy of a 19-bp sequence in the 5' untranslated region (UTR), whereas this sequence is duplicated and tandemly arranged in allele *2. Studies showed that the allelic variation of LAPTM4B was associated with the genetic susceptibility of hepatocellular carcinoma but not with that of esophageal squamous cell carcinoma. This study was designed to investigate the possible association between the allelic variation of LAPTM4B and the genetic susceptibility of gastric cancer.

MATERIALS AND METHODS

The genotype of LAPTM4B was analyzed in 350 unrelated healthy adult individuals and 214 patients with gastric cancer by utilizing polymerase chain reaction based on specific primers. The genotypic distribution of LAPTM4B was analyzed by chi(2) test.

RESULTS

The allelic frequencies of the *2 were 33.88% and 24.14% in the gastric cancer group and the healthy control group, respectively, which was significantly different between the two groups (P < 0.001). There was a significant difference in the overall genotypic distribution between the patients and the controls (P = 0.023). The risk of suffering from gastric cancer was increased 1.819 times in the individuals of the *1/2 genotype [95% confidence interval (CI) 1.273-2.601] and 2.387 times in the individuals of the *2/2 genotype of LAPTM4B (95% CI 1.195-4.767) compared with the *1/1 genotype. No association between the genotypic distribution of LAPTM4B and the clinical information on patients of gastric cancer such as age, pathological type, differentiation classification of TNM, and infection of hepatitis B virus was shown.

CONCLUSION

This study indicated that allele *2 of LAPTM4B might be the risk factor of gastric cancer, which could be associated with genetic susceptibility of gastric cancer.

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Global gene expression profile of human cord blood-derived CD133+ cells

Human cord blood (CB)-derived CD133+ cells carry characteristics of primitive hematopoietic cells and proffer an alternative for CD34+ cells in hematopoietic stem cell (HSC) transplantation. To characterize the CD133+ cell population on a genetic level, a global expression analysis of CD133+ cells was performed using oligonucleotide microarrays. CD133+ cells were purified from four fresh CB units by immunomagnetic selection. All four CD133+ samples showed significant similarity in their gene expression pattern, whereas they differed clearly from the CD133- control samples. In all, 690 transcripts were differentially expressed between CD133+ and CD133- cells. Of these, 393 were increased and 297 were decreased in CD133+ cells. The highest overexpression was noted in genes associated with metabolism, cellular physiological processes, cell communication, and development. A set of 257 transcripts expressed solely in the CD133+ cell population was identified. Colony-forming unit (CFU) assay was used to detect the clonal progeny of precursors present in the studied cell populations. The results demonstrate that CD133+ cells express primitive markers and possess clonogenic progenitor capacity. This study provides a gene expression profile for human CD133+ cells. It presents a set of genes that may be used to unravel the properties of the CD133+ cell population, assumed to be highly enriched in HSCs.