Gastric Carcinoma with low ROR alpha, low E- Cadherin and High LAPTM4B Immunohistochemical Profile; is associated with unfavorable prognosis in Egyptian patients.

In view of multiplicity of carcinogenic pathways of gastric carcinoma (GC), poor survival and chemotherapy resistance, more analysis of these pathways is required for prediction of prognosis and developing new therapeutic targets. Knocking down of RORα; induces tumor cell proliferation and epithelial-mesenchymal transition (EMT). LAPTM4B has been suggested to be associated with EMT which promote tumor invasion. This work aimed to investigate prognostic role of RORα, LAPTM4B, and E-Cadherin expression in GC. This retrospective immunohistochemical study assesses the expression of RORα, LAPTM4B, and E-Cadherin in 73 primary gastric carcinomas. Low RORα and high LAPTM4B expression in GC cases were associated with unfavorable prognostic factors such as positive lymph nodes, and high tumor budding. E-Cadherin heterogeneous staining was associated with poor prognostic criteria, such as diffuse type GC and high tumor budding. Low RORα, high LAPTM4B, and heterogeneous E-Cadherin were the most common immunohistochemical profile in GC cases. Low RORα expression showed poor prognostic impact on overall patient survival. In conclusion, RORα and LAPTM4B may have crucial role in GC aggressiveness. The predominance of low RORα, high LAPTM4B, and heterogeneous or negative E-Cadherin immunohistochemical profile in GC cases with unfavorable pathological parameters suggested that this profile may predict tumor behavior.

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.

Lysosomal-associated transmembrane protein 4B regulates ceramide-induced exosome release.

Exosomes are extracellular vesicles that mediate the transport of intracellular molecules, including neurodegenerative agents. Exogenously administrated ceramides have been implicated in the acceleration of exosome production by neurons; however, the molecular machinery involved in this process is unknown. Here, we found that ceramides, especially those consisting of long fatty acids, were internalized into the endocytic pathway in neuroblastoma SH-SY5Y cells to induce exosome secretion through lysosome-associated protein transmembrane 4B (LAPTM4B). Knockdown of LAPTM4B inhibited the ceramide-mediated increase in exosome release completely. Fluorescence microscopy observations indicated that exogenous ceramides promote the transport of multivesicular bodies to the plasma membranes in a LAPTM4B-dependent manner. Similarly, inhibition of acid ceramidase, which tends to induce intracellular ceramide accumulation, increased exosome production by SH-SY5Y cells in a LAPTM4B-dependent manner. Furthermore, the level of amyloid-ß protein (Aß) was decreased in neuronal cells following treatment with exogenous ceramide or inhibition of acid ceramidase, and this effect was attributed to the LAPTM4B-dependent efflux of Aß-containing exosomes. Overall, these findings reveal the novel machinery involved in exosome secretion regulated by ceramides and LAPTM4B, and may contribute to efforts to ameliorate the cellular accumulation of neurodegenerative agents such as Aß.

[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.

SNHG16 promotes cell proliferation and migration through sponging miR-132 in melanoma.

Melanoma, which originates from the transformation of normal melanocytes, is one of the three main types of skin cancer. We aimed to explore the functions of SNHG16 and miR-132 in melanoma. CCK-8, Transwell assays were used to measure the viability and migration, respectively. Spearman's correlation analysis was performed to analyze the relationship between the expression of SNHG16, miR-132 and LAPTM4B in melanoma tissues. SNHG16 was overexpressed, and miR-132 was low expressed in melanoma tissues and cell lines. Moreover, overexpression of SNHG16 was associated with poor prognosis of melanoma patients. The expression of SNHG16 had a negative connection with the expression of miR-132, and it had a positive relationship with the expression of LAPTM4B in melanoma tissues. Knockdown of SNHG16 or overexpression of miR-132 inhibited SK-MEL-2 cell proliferation and migration. In addition, we confirmed that SNHG16 directly binding to miR-132 promotes the expression of LAPTM4B, facilitating the tumorigenesis of melanoma. SNHG16 promotes the expression of LAPTM4B by sponging miR-132, thereby acting as an oncogene in melanoma. This study demonstrated that the lncRNA-miRNA-mRNA signal cascade existed in melanoma, which may help elucidate the tumorigenesis and development mechanism of melanoma.

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.

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.

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 4ß (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 is a novel diagnostic and prognostic marker for lung adenocarcinoma and associated with mutant EGFR.

BACKGROUND: Lysosomal-associated protein transmembrane-4 beta (LAPTM4B), a novel oncogene, promotes tumorigenesis and may be a potential prognostic biomarker in several cancers. This study was to determine the clinical significance and biological roles of LAPTM4B in lung adenocarcinoma (LAC). METHODS: LAPTM4B expression was analyzed by immunohistochemistry (IHC) of 63 LAC tumors. Serum levels of LAPTM4B were measured by enzyme-linked immuosorbent assays (ELISA). The study included untreated group (n = 216), chemotherapy group (n = 29), chemotherapy efficacy group (n = 179), EGFR-TKIs group (n = 57) and 68 healthy controls. Statistical analysis was performed to explore the correlation between LAPTM4B expression and clinicopathological parameters in LAC. Kaplan-Meier analysis was performed to assess the prognostic significance of LAPTM4B in LAC. In vitro assays were performed to assess the biological roles of LAPTM4B in LAC cells. Western blotting assays were examined to identify the underlying pathways involved in the tumor-promoting role of LAPTM4B. RESULTS: We found LAPTM4B was upregulated in LAC tissues and high LAPTM4B expression was significantly correlated with poor prognosis. Serum LAPTM4B levels were significantly decreased after chemotherapy. Patients in invalid response group showed higher LAPTM4B levels than the valid response group. Overexpression of LAPTM4B promoted, while silencing of LAPTM4B inhibited proliferation, invasion and migration of LAC cells via PI3K/AKT and EMT signals. LAPTM4B expression level was associated with epidermal growth factor receptor (EGFR) gene mutations. In addition, LAPTM4B plays important roles in EGFR-promoted cell proliferation, migration and invasion and gefitinib-induced apoptosis. CONCLUSIONS: Collectively, our data propose that LAPTM4B may be a cancer biomarker for LAC and a potential therapeutic target which facilitates the development of a novel therapeutic strategy against LAC.

LAPTM4B Predicts Axillary Lymph Node Metastasis in Breast Cancer and Promotes Breast Cancer Cell Aggressiveness in Vitro.

PURPOSE: Lysosome-associated protein transmembrane-4 beta (LAPTM4B) is associated with the prognosis of several human malignancies. In this study, the role of LAPTM4B in the metastatic potential of breast cancer (BC) and its underlying molecular mechanisms were investigated. METHODS: The relationship between LAPTM4B expression and axillary lymph node metastasis was determined in 291 BC specimens by immunohistochemistry. The expression of LAPTM4B in paired BC cells was overexpressed and inhibited to analyse the role of LAPTM4B in the aggressiveness of BC. Cell proliferation, migration and invasion were assessed in vitro. Metastasis-related protein levels were detected through Western blot. RESULTS: Immunohistochemical staining demonstrated that high expression level of LAPTM4B was independently associated with axillary lymph node metastasis (odds ratio=2.428; 95%CI=1.333- 4.425; P=0.004). The LAPTM4B inhibition in MCF-7 cells inhibited cell proliferation, migration, invasion, and resulted in simultaneous downregulation of phosphorylated N-cadherin, vimentin, and upregulation of E-cadherin. By contrast, the LAPTM4B overexpression promoted cell proliferation, migration, invasion, and led to simultaneous upregulation of N-cadherin, vimentin, and downregulation of E-cadherin in T47D cells. CONCLUSIONS: High expression level of LAPTM4B predicts tumor metastatic potential in patients with BC. Our results provide the first evidence of the role of LAPTM4B as an Epithelial-mesenchymal transition (EMT) inducer that promotes aggressiveness in BC cells.

LAPTM4B-35 is a novel prognostic factor for glioblastoma.

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

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

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

LAPTM4B promotes AML progression through regulating RPS9/STAT3 axis.

Acute myeloid leukemia (AML) is a heterogeneous disorder with high morbidity and mortality under the existing treatment strategy. Here, we found that lysosome-associated protein transmembrane 4 beta (LAPTM4B) was frequently upregulated in AML, and high LAPTM4B was associated with poor outcome. Moreover, LAPTM4B promoted leukemia progression in vitro and in vivo. Mechanically, LAPTM4B interacted with RPS9, and positively regulated RPS9 protein stability, which enhanced leukemia cell progression via activating STAT3. Our findings indicate for the first time that LAPTM4B contributes to leukemia progression in a RPS9/STAT3-dependent manner, suggesting that LAPTM4B may serve as a promising target for treatment of AML.

Autophagy-related gene LAPTM4B promotes the progression of renal clear cell carcinoma and is associated with immunity.

Renal cell carcinoma (RCC) is a common urologic disease. Currently, surgery is the primary treatment for renal cancer; immunotherapy is not as effective a treatment strategy as expected. Hence, understanding the mechanism in the tumor immune microenvironment (TME) and exploring novel immunotherapeutic targets are considered important. Recent studies have demonstrated that autophagy could affect the immune environment of renal cell carcinoma and induce proliferation and apoptosis of cancer cells. By comparing lysosomal genes and regulating autophagy genes, we identified the LAPTM4B gene to be related to RCC autophagy. By analyzing the TCGA-KIRC cohort using bioinformatics, we found M2 macrophages associated with tumor metastasis to be significantly increased in the immune microenvironment of patients with high expression of LAPTM4B. GO/KEGG/GSEA/GSVA results showed significant differences in tumor autophagy- and metastasis-related pathways. Single-cell sequencing was used to compare the expression of LAPTM4B in different cell types and obtain the differences in lysosomal and autophagy pathway activities in different ccRCC cells. Subsequently, we confirmed the differential expression of LAPTM4B in renal cell carcinoma of different Fuhrman grades using western blotting. Downregulation of LAPTM4B expression significantly reduced the proliferation of renal cell carcinoma cells and promoted cell apoptosis through cell experiments. Overall, our study demonstrated that the autophagy-related gene LAPTM4B plays a critical role in the TME of RCC, and suggested that LAPTM4B is a potential therapeutic target for RCC immunotherapy.

Role and mechanism of action of LAPTM4B in EGFR-mediated autophagy.

LAPTM4B is upregulated in the majority of types of cancer and associated with cancer cell proliferation, survival and drug resistance, as well as poor patient prognosis. LAPTM4B knockdown inhibits autophagosome maturation in the context of metabolic stress. Autophagy is a homeostatic process that degrades and recycles intracellular components in response to metabolic stress. The function of autophagy is dual, as this process can either have a tumor suppressor or an oncogenic role. EGFR serves an important role in determining the tumor-suppressive or oncogenic roles of autophagy. EGFR family members regulate autophagy through various signaling pathways, including PI3K/AKT signaling. Notably, LAPTM4B also promotes cancer cell proliferation via the PI3K/AKT signaling pathway. In addition, LAPTM4B can enhance and prolong EGFR signal transduction by blocking active EGFR intraluminal sorting and lysosomal degradation. Thus, LAPTM4B may be associated with autophagy through EGFR signaling. The present review proposed that LAPTM4B participates in regulating autophagy through the EGFR pathway.

LAPTM4B promotes the progression of bladder cancer by stimulating cell proliferation and invasion.

Bladder cancer is a highly metastatic tumor and one of the most common malignant tumors originating in the urinary system. Due to the complicated etiology and lack of significant early symptoms, the diagnosis and treatment of bladder cancer is difficult. Lysosome-associated transmembrane protein 4ß (LAPTM4B) was reported to be involved in the development and progression of several types of tumor, however, its potential effect on the development and metastasis of bladder cancer is still unclear. Immunohistochemistry was performed to detect the protein expression level of LAPTM4B in bladder cancer tissues and short hairpin RNAs targeting LAPTM4B were transfected into bladder cancer cells to knockdown its expression. MTT and colony formation assays were performed to detect cell proliferation, while wound healing and Transwell invasion assays were performed to detect cell migration and invasion, respectively. In addition, tumor growth assays were performed to confirm the effects of LAPTM4B in mice. The present study demonstrated that LAPTM4B was associated with the prognosis of patients with bladder cancer. In addition, LAPTM4B was associated with clinical characteristics, including tumor stage and recurrence. The results further showed that LAPTM4B knockdown could suppress the proliferation of bladder cancer cell lines. In addition, the migration and invasion of T24 and 5637 cells was suppressed following LAPTM4B knockdown in vitro. The in vivo data confirmed that knockdown of LAPTM4B markedly inhibited tumor growth and metastasis in mice. In summary, the results from the present study provide strong evidence of the effects of LAPTM4B in bladder cancer progression.

Noninvasively visualize the expression of LAPTM4B protein using a novel 18F-labeled peptide PET probe in hepatocellular carcinoma.

OBJECTIVE: Lysosomal protein transmembrane 4 beta (LAPTM4B) is selectively expressed in hepatocellular carcinoma (HCC) cells and thus a potential biomarker for diagnosing HCC. In this study, we designed a novel 18F-labeled PET probe to non-invasively visualize LAPTM4B expression in mouse model of HCC tumor. METHODS: A PET targeting tracer named [18F]FP-LAP2H was radio-synthesized using a LAPTM4B targeting peptide, LAP2H, coupled with 4-nitrophenyl-2-[18F]fluoropropionate ([18F]NFP). Radio-stability, cell uptake, micro PET/CT imaging and ex vivo biodistribution were performed for determining its stability, cell binding specificity, and tumor targeting in vivo. RESULTS: [18F]FP-LAP2H was successfully synthesized with radiochemical yields of 6-14% (decay-corrected yield) and molar activity of 10-44 GBq/µmol. The tracer showed stable (~90%) in phosphate-buffered saline, pH 7.4, and in human serum (~80%) for 2 h. In vitro cell uptake studies indicated the radioactivity accumulation in HCC cells was LAPTM4B protein-specific. Micro PET/CT demonstrated that implanted LAPTM4B positive HepG2 and BEL7402 tumors could be clearly visualized. The ex vivo biodistribution studies demonstrated that the tumor/liver ratio were 1.80 ± 0.65 and 2.09 ± 0.68 in implanted HepG2 and BEL7402 tumors respectively. Negative control and blocking experiments revealed that the radioactivity uptake in the HCC tumor was LAPTM4B protein-specific. CONCLUSIONS: [18F]FP-LAP2H appears to be a potential PET tracer for imaging LAPTM4B-positive HCC tumor. Further endeavors need to do to improve tumor/liver ratio.

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.

Long Non-Coding RNA TP73-AS1 Promotes the Development of Lung Cancer by Targeting the miR-27b-3p/LAPTM4B Axis.

PURPOSE: Long non-coding RNA P73 antisense RNA 1T (TP73-AS1) is a newly discovered lncRNA involved in the occurrence and development of several cancers. However, its role in lung cancer has not been well investigated yet. METHODS: The expressions of TP73-AS1, microRNA-27b-3p (miR-27b-3p) and lysosomal-associated protein transmembrane-4 Beta (LAPTM4B) were detected by quantitative real-time polymerase chain reaction (qRT-PCR). The cell proliferation, apoptosis, migration and invasion were detected by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), Annexin V-FITC/PI and transwell assays, respectively. Tumor xenografts were applied to explore the role of TP73-AS1 in vivo. The target relationship was predicted by StarBase v.2.0 or TargetScan and confirmed by luciferase reporter assay. Pearson's coefficient assay was applied to assess the expression correlation between two groups. Protein expression levels were detected by Western blot. RESULTS: We found that TP73-AS1 was strikingly up-regulated in lung cancer tissues and cells. TP73-AS1 depletion inhibited the growth and metastasis of lung cancer cells in vitro. Furthermore, TP73-AS1 could act as an endogenous sponge by directly binding miR-27b-3p, and a notable inverse correlation between them was also discovered. Importantly, knockdown of miR-27b-3p could reverse the inhibitory effects of TP73-AS1 depletion on the growth and metastasis of lung cancer cells. Besides, LAPTM4B was directly targeted by miR-27b-3p and could be co-regulated by TP73-AS1 and miR-27b-3p in lung cancer cells. Silencing TP73-AS1 hampered tumor growth by regulating miR-27b-3p/LAPTM4B axis in vivo. CONCLUSION: TP73-AS1 promoted the progression of lung cancer through regulating miR-27b-3p/LAPTM4B axis and it might be a potential target for diagnosis and treatment of lung cancer.

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-4ß 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.