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

LAPTM4B-35 promotes cancer cell migration via stimulating integrin beta1 recycling and focal adhesion dynamics

Metastasis is the main cause of cancer patients' death despite tremendous efforts invested in developing the related molecular mechanisms. During cancer cell migration, cells undergo dynamic regulation of filopodia, focal adhesion, and endosome trafficking. Cdc42 is imperative for maintaining cell morphology and filopodia, regulating cell movement. Integrin beta1 activates on the endosome, the majority of which distributes itself on the plasma membrane, indicating that endocytic trafficking is essential for this activity. In cancers, high expression of lysosome‐associated protein transmembrane 4B (LAPTM4B) is associated with poor prognosis. LAPTM4B‐35 has been reported as displaying plasma membrane distribution and being associated with cancer cell migration. However, the detailed mechanism of its isoform‐specific distribution and whether it relates to cell migration remain unknown. Here, we first report and quantify the filopodia localization of LAPTM4B‐35: mechanically, that specific interaction with Cdc42 promoted its localization to the filopodia. Furthermore, our data show that LAPTM4B‐35 stabilized filopodia and regulated integrin beta1 recycling via interaction and cotrafficking on the endosome. In our zebrafish xenograft model, LAPTM4B‐35 stimulated the formation and dynamics of focal adhesion, further promoting cancer cell dissemination, whereas in skin cancer patients, LAPTM4B level correlated with poor prognosis. In short, this study establishes an insight into the mechanism of LAPTM4B‐35 filopodia distribution, as well as into its biological effects and its clinical significance, providing a novel target for cancer therapeutics development.

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.

Clinical impact of circulating LAPTM4B-35 in pancreatic ductal adenocarcinoma

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

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.

AP4 positively regulates LAPTM4B to promote hepatocellular carcinoma growth and metastasis, while reducing chemotherapy sensitivity

Polymorphisms of the lysosomal-associated protein transmembrane-4 beta (LAPTM4B) gene are related to various forms of tumour susceptibility, which led us to hypothesize that some unique transcription factors targeting this polymorphism region may affect the biological function of LAPTM4B in tumour progression. In this study, we found that the transcription factor AP4 directly binds to the polymorphism region of the LAPTM4B gene promoter and induces its transcription. In addition, we demonstrated that AP4 promotes hepatocellular carcinoma (HCC) cell proliferation and metastasis and depresses chemotherapy sensitivity via LAPTM4B by activating the PI3K/AKT signalling pathway and caspase-dependent pathway. Interestingly, we found that AP4 could not only regulate LAPTM4B by directly binding to the promoter, but also be regulated via a positive feedback mechanism involving LAPTM4B acting on c-myc. Finally, we showed that AP4 and LAPTM4B are highly coexpressed in HCC tissues, and their coexpression may be a marker of poor prognosis. These findings provide evidence of the expression and functional coupling between AP4 and LAPTM4B and shed light on the regulation of LAPTM4B and its function in liver cancer.

Overexpressed LAPTM4B-35 is a risk factor for cancer recurrence and poor prognosis in non-small-cell lung cancer

BACKGROUND

The expression levels and clinical significances of Lysosomal-associated protein transmembrane-4β-35 (LAPTM4B-35) protein are unknown in the non-small-cell lung cancer (NSCLC). This study aimed to explore the expression and prognostic value of LAPTM4B-35 in NSCLC patients.

METHODS

The clinicopathological and survival data of 107 NSCLC patients who received radical surgery from 2007 and 2011 were reviewed. The LAPTM4B-35 expression of the paired tumors and adjacent normal specimens were detected, and the association between LAPTM4B-35 and clinical variables was explored. Kaplan-Meier analysis and Cox regression (Proportional hazard model) were performed to investigate the prognostic significance for NSCLC.

RESULTS

LAPTM4B-35 was over expressed in NSCLC tissues. The elevated LAPTM4B-35 expression was associated with cancer recurrence (P = 0.031). The 5-year median OS and PFS were significantly worse in the LAPTM4B-35 overexpressed group. Multivariate Cox analysis showed that LAPTM4B-35 over-expression was an independent factor for OS and PFS in NSCLC(P = 0.018, P = 0.026, respectively).

CONCLUSIONS

The overexpressed LAPTM4B-35 was an independent prognostic biomarker for NSCLC, which could predict cancer recurrence and poor over survival. And that may be applied as potential target for NSCLC treatment.

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

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

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

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

LAPTM4B-35、CTGF蛋白在食管胃交界部腺癌中的表达及其意义

目的

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

方法

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

结果

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

结论

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

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.