Expression of lysosome-associated membrane proteins in human colorectal neoplasms and inflammatory diseases

INPP4B promotes PDAC aggressiveness via PIKfyve and TRPML-1-mediated lysosomal exocytosis

Aggressive solid malignancies, including pancreatic ductal adenocarcinoma (PDAC), can exploit lysosomal exocytosis to modify the tumor microenvironment, enhance motility, and promote invasiveness. However, the molecular pathways through which lysosomal functions are co-opted in malignant cells remain poorly understood. In this study, we demonstrate that inositol polyphosphate 4-phosphatase, Type II (INPP4B) overexpression in PDAC is associated with PDAC progression. We show that INPP4B overexpression promotes peripheral dispersion and exocytosis of lysosomes resulting in increased migratory and invasive potential of PDAC cells. Mechanistically, INPP4B overexpression drives the generation of PtdIns(3,5)P2 on lysosomes in a PIKfyve-dependent manner, which directs TRPML-1 to trigger the release of calcium ions (Ca2+). Our findings offer a molecular understanding of the prognostic significance of INPP4B overexpression in PDAC through the discovery of a novel oncogenic signaling axis that orchestrates migratory and invasive properties of PDAC via the regulation of lysosomal phosphoinositide homeostasis.

Resistance to abemaciclib is associated with increased metastatic potential and lysosomal protein deregulation in breast cancer cells

Cyclin dependent kinase 4 and 6 inhibitors such as abemaciclib are routinely used to treat metastatic estrogen receptor positive (ER+) breast cancer. However, adaptive mechanisms inhibit their effectiveness and allow for disease progression. Using ER+ breast cancer cell models, we show that acquired resistance to abemaciclib is accompanied by increase in metastatic potential. Mass spectrometry-based proteomics from abemaciclib sensitive and resistant cells showed that lysosomal proteins including CTSD (cathepsin D), cathepsin A and CD68 were significantly increased in resistant cells. Combination of abemaciclib and a lysosomal destabilizer, such as hydroxychloroquine (HCQ) or bafilomycin A1, resensitized resistant cells to abemaciclib. Also, combination of abemaciclib and HCQ decreased migration and invasive potential and increased lysosomal membrane permeability in resistant cells. Prosurvival B cell lymphoma 2 (BCL2) protein levels were elevated in resistant cells, and a triple treatment with abemaciclib, HCQ, and BCL2 inhibitor, venetoclax, significantly inhibited cell growth compared to treatment with abemaciclib and HCQ. Furthermore, resistant cells showed increased levels of Transcription Factor EB (TFEB), a master regulator of lysosomal-autophagy genes, and siRNA mediated knockdown of TFEB decreased invasion in resistant cells. TFEB was found to be mutated in a subset of invasive human breast cancer samples, and overall survival analysis in ER+, lymph node-positive breast cancer showed that increased TFEB expression correlated with decreased survival. Collectively, we show that acquired resistance to abemaciclib leads to increased metastatic potential and increased levels of protumorigenic lysosomal proteins. Therefore, the lysosomal pathway could be a therapeutic target in advanced ER+ breast cancer.

LAMP2A, LAMP2B and LAMP2C: similar structures, divergent roles

LAMP2 (lysosomal associated membrane protein 2) is one of the major protein components of the lysosomal membrane. There currently exist three LAMP2 isoforms, LAMP2A, LAMP2B and LAMP2C, and they vary in distribution and function. LAMP2A serves as a receptor and channel for transporting cytosolic proteins in a process called chaperone-mediated autophagy (CMA). LAMP2B is required for autophagosome-lysosome fusion in cardiomyocytes and is one of the components of exosome membranes. LAMP2C is primarily implicated in a novel type of autophagy in which nucleic acids are taken up into lysosomes for degradation. In this review, the current evidence for the function of each LAMP2 isoform in various pathophysiological processes and human diseases, as well as their possible mechanisms, are comprehensively summarized. We discuss the evolutionary patterns of the three isoforms in vertebrates and provide technical guidance on investigating these isoforms. We are also concerned with the newly arising questions in this particular research area that remain unanswered. Advances in the functions of the three LAMP2 isoforms will uncover new links between lysosomal dysfunction, autophagy and human diseases.Abbreviation: ACSL4: acyl-CoA synthetase long-chain family member 4; AD: Alzheimer disease; Ag: antigens; APP: amyloid beta precursor protein; ATG14: autophagy related 14; AVSF: autophagic vacuoles with unique sarcolemmal features; BBC3/PUMA: BCL2 binding component 3; CCD: C-terminal coiled coil domain; CMA: chaperone-mediated autophagy; CVDs: cardiovascular diseases; DDIT4/REDD1: DNA damage inducible transcript 4; ECs: endothelial cells; ER: endoplasmic reticulum; ESCs: embryonic stem cells; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GBA/β-glucocerebrosidase: glucosylceramidase beta; GSCs: glioblastoma stem cells; HCC: hepatocellular carcinoma; HD: Huntington disease; HSCs: hematopoietic stem cells; HSPA8/HSC70: heat shock protein family A (Hsp70) member 8; IL3: interleukin 3; IR: ischemia-reperfusion; LAMP2: lysosomal associated membrane protein 2; LDs: lipid droplets; LRRK2: leucine rich repeat kinase 2; MA: macroautophagy; MHC: major histocompatibility complex; MST1: macrophage stimulating 1; NAFLD: nonalcoholic fatty liver disease; NFE2L2/NRF2: NFE2 like bZIP transcription factor 2; NLRP3: NLR family pyrin domain containing 3; PARK7: Parkinsonism associated deglycase; PD: Parkinson disease; PEA15/PED: proliferation and apoptosis adaptor protein 15; PKM/PKM2: pyruvate kinase M1/2; RA: rheumatoid arthritis; RARA: retinoic acid receptor alpha; RCAN1: regulator of calcineurin 1; RCC: renal cell carcinoma; RDA: RNautophagy and DNautophagy; RNAi: RNA interference; RND3: Rho Family GTPase 3; SG-NOS3/eNOS: deleterious glutathionylated NOS3; SLE: systemic lupus erythematosus; TAMs: tumor-associated macrophages; TME: tumor microenvironment; UCHL1: ubiquitin C-terminal hydrolase L1; VAMP8: vesicle associated membrane protein 8.

The functions of SID1 transmembrane family, member 2 (Sidt2)

The SID1 transmembrane family, member 2, namely, Sidt2, is a highly glycosylated multichannel lysosomal transmembrane protein, but its specific physiological function remains unknown. Lysosomal membrane proteins are very important for the executive functioning of lysosomes. As an important part of the lysosomal membrane, Sidt2 can maintain the normal morphology of lysosomes and help stabilize them from the acidic pH environment within. As a receptor/transporter, it binds and transports nucleic acids and mediates the uptake and degradation of RNA and DNA by the lysosome. During glucose metabolism, deletion of Sidt2 can cause an increase in fasting blood glucose and the impairment of grape tolerance, which is closely related to the secretion of insulin. During lipid metabolism, the loss of Sidt2 can cause hepatic steatosis and lipid metabolism disorders and can also play a role in signal regulation and transport. Here, we review the function of the lysosomal membrane protein Sidt2, and focus on its role in glucose and lipid metabolism, autophagy and nucleotide (DNA/RNA) transport.

The endocytic receptor protein LRP-1 modulate P-glycoprotein mediated drug resistance in MCF-7 cells

Multidrug resistance (MDR) is a major obstacle to successful cancer chemotherapy. A typical form of MDR is due to the overexpression of membrane transport proteins., such as Glycoprotein-P (P-gp), resulting in an increased drug efflux preventing drug cytotoxicity. P-gp is mainly localized on the plasma membrane; however, it can also be endocytosed resulting in the trafficking of P-gp in endoplasmic reticulum, Golgi, endosomes, and lysosomes. The lysosomal P-gp has been found to be capable of transporting and sequestering P-gp substrates (e.g., Doxorubicin (Dox)) into lysosomes to protect cells against cytotoxic drugs. Many translational studies have shown that low-density lipoprotein receptor-related protein-1 (LRP-1) is involved in endocytosis and regulation of signalling pathways. LRP-1 mediates the endocytosis of a diverse set of extracellular ligands that play important roles in tumor progression. Here, we investigated the involvement of LRP-1 in P-gp expression and subcellular redistribution from the cell surface to the lysosomal membrane by endocytosis and its potential implication in P-gp-mediated multidrug resistance in MCF-7 cells. Our results showed that MCF-7 resistant cells (MCF-7R) overexpressed the P-gp, LRP-1 and LAMP-1 and were 11.66-fold resistant to Dox. Our study also revealed that in MCF-7R cells, lysosomes were predominantly high density compared to sensitized cells and P-gp was localized in the plasma membrane and lysosomes. LRP-1 blockade reduced lysosomes density and level of LAMP-1 and P-gp. It also affected the subcellular distribution of P-gp. Under these conditions, we restored Dox nuclear uptake and ERK 1/2 activation thus leading to MCF-7R cell sensitization to Dox. Our data suggest that LRP-1 is able to modulate the P-gp expression and subcellular redistribution by endocytosis and to potentiate the P-gp-acquired Dox resistance.

Cellular transformation promotes the incorporation of docosahexaenoic acid into the endolysosome-specific lipid bis(monoacylglycerol)phosphate in breast cancer

Bis(monoacylglycero)phosphates (BMPs), a class of lipids highly enriched within endolysosomal organelles, are key components of the lysosomal intraluminal vesicles responsible for activating sphingolipid catabolic enzymes. While BMPs are understudied relative to other phospholipids, recent reports associate BMP dysregulation with a variety of pathological states including neurodegenerative diseases and lysosomal storage disorders. Since the dramatic lysosomal remodeling characteristic of cellular transformation could impact BMP abundance and function, we employed untargeted lipidomics approaches to identify and quantify BMP species in several in vitro and in vivo models of breast cancer and comparative non-transformed cells and tissues. We observed lower BMP levels within transformed cells relative to normal cells, and consistent enrichment of docosahexaenoic acid (22:6) fatty acyl chain-containing BMP species in both human- and mouse-derived mammary tumorigenesis models. Our functional analysis points to a working model whereby 22:6 BMPs serve as reactive oxygen species scavengers in tumor cells, protecting lysosomes from oxidant-induced lysosomal membrane permeabilization. Our findings suggest that breast tumor cells might divert polyunsaturated fatty acids into BMP lipids as part of an adaptive response to protect their lysosomes from elevated reactive oxygen species levels, and raise the possibility that BMP-mediated lysosomal protection is a tumor-specific vulnerability that may be exploited therapeutically.

Transcription of Autophagy Associated Gene Expression as Possible Predictors of a Colorectal Cancer Prognosis

(1) Background: Autophagy plays a dual role in oncogenesis-it contributes to the growth of the tumor and can inhibit its development. The aim of this study was to assess changes in the transcriptional activity of LAMP-2, BECN1, PINK1, and FOXO1 genes involved in the autophagy process in histopathologically confirmed adenocarcinoma sections of colorectal cancer: (2) Methods: A gene expression profile analysis was performed using HG-U133A and the RT-qPCR reaction. The transcriptional activity of genes was compared in sections of colorectal cancer in the four clinical stages (CSI-CSIV) concerning the control group; (3) Results: In CSI, the transcriptional activity of the PINK1 gene is highest; in CS II, the LAMP-2 gene is highest, while FOXO1 increases gradually from CSI reaching a maximum in CSIII. There is no BECN1 gene expression in colorectal cancer cells; (4) Conclusions: The observed differences in the mRNA concentration profile of autophagy-related genes in colon cancer specimens may indicate the role of autophagy in the pathogenesis of this cancer. Genes involved in autophagy may be diagnostic tools for colorectal cancer screening and personalized therapy in the future.

Subtypes analysis and prognostic model construction based on lysosome-related genes in colon adenocarcinoma

Background: Lysosomes are essential for the development and recurrence of cancer. The relationship between a single lysosome-related gene and cancer has previously been studied, but the relationship between the lysosome-related genes (LRGs) and colon adenocarcinoma (COAD) remains unknown. This research examined the role of lysosome-related genes in colon adenocarcinoma. Methods: 28 lysosome-related genes associated with prognosis (PLRGs) were found by fusing the gene set that is differently expressed between tumor and non-tumor in colon adenocarcinoma with the gene set that is related to lysosomes. Using consensus unsupervised clustering of PLRGs, the colon adenocarcinoma cohort was divided into two subtypes. Prognostic and tumor microenvironment (TME) comparisons between the two subtypes were then made. The PLRGs_score was constructed using the least absolute shrinkage and selection operator regression (LASSO) method to quantify each patient's prognosis and provide advice for treatment. Lastly, Western Blot and immunohistochemistry (IHC) were used to identify MOGS expression at the protein level in colon adenocarcinoma tissues. Results: PLRGs had more somatic mutations and changes in genetic level, and the outcomes of the two subtypes differed significantly in terms of prognosis, tumor microenvironment, and enrichment pathways. Then, PLRGs_score was established based on two clusters of differential genes in the cancer genome atlas (TCGA) database, and external verification was performed using the gene expression omnibus (GEO) database. Then, we developed a highly accurate nomogram to enhance the clinical applicability of the PLRGs_score. Finally, a higher PLRGs_score was associated with a poorer overall survival (OS), a lower tumor mutation burden (TMB), a lower cancer stem cell (CSC) index, more microsatellite stability (MSS), and a higher clinical stage. MOGS was substantially elevated at the protein level in colon adenocarcinoma as additional confirmation. Conclusion: Overall, based on PLRGs, we identified two subtypes that varied significantly in terms of prognosis and tumor microenvironment. Then, in order to forecast patient prognosis and make treatment suggestions, we developed a diagnostic model with major significance for prognosis, clinical relevance, and immunotherapy. Moreover, we were the first to demonstrate that MOGS is highly expressed in colon adenocarcinoma.

Keratin Promotes Differentiation of Keratinocytes Seeded on Collagen/Keratin Hydrogels

Keratinocytes undergo a complex process of differentiation to form the stratified stratum corneum layer of the skin. In most biomimetic skin models, a 3D hydrogel fabricated out of collagen type I is used to mimic human skin. However, native skin also contains keratin, which makes up 90% of the epidermis and is produced by the keratinocytes present. We hypothesized that the addition of keratin (KTN) in our collagen hydrogel may aid in the process of keratinocyte differentiation compared to a pure collagen hydrogel. Keratinocytes were seeded on top of a 100% collagen or 50/50 C/KTN hydrogel cultured in either calcium-free (Ca-free) or calcium+ (Ca+) media. Our study demonstrates that the addition of keratin and calcium in the media increased lysosomal activity by measuring the glucocerebrosidase (GBA) activity and lysosomal distribution length, an indication of greater keratinocyte differentiation. We also found that the presence of KTN in the hydrogel also increased the expression of involucrin, a differentiation marker, compared to a pure collagen hydrogel. We demonstrate that a combination (i.e., containing both collagen and kerateine or “C/KTN”) hydrogel was able to increase keratinocyte differentiation compared to a pure collagen hydrogel, and the addition of calcium further increased the differentiation of keratinocytes. This multi-protein hydrogel shows promise in future models or treatments to increase keratinocyte differentiation into the stratum corneum.

Linking Late Endosomal Cholesterol with Cancer Progression and Anticancer Drug Resistance

Cancer cells undergo drastic metabolic adaptions to cover increased bioenergetic needs, contributing to resistance to therapies. This includes a higher demand for cholesterol, which often coincides with elevated cholesterol uptake from low-density lipoproteins (LDL) and overexpression of the LDL receptor in many cancers. This implies the need for cancer cells to accommodate an increased delivery of LDL along the endocytic pathway to late endosomes/lysosomes (LE/Lys), providing a rapid and effective distribution of LDL-derived cholesterol from LE/Lys to other organelles for cholesterol to foster cancer growth and spread. LDL-cholesterol exported from LE/Lys is facilitated by Niemann–Pick Type C1/2 (NPC1/2) proteins, members of the steroidogenic acute regulatory-related lipid transfer domain (StARD) and oxysterol-binding protein (OSBP) families. In addition, lysosomal membrane proteins, small Rab GTPases as well as scaffolding proteins, including annexin A6 (AnxA6), contribute to regulating cholesterol egress from LE/Lys. Here, we summarize current knowledge that links upregulated activity and expression of cholesterol transporters and related proteins in LE/Lys with cancer growth, progression and treatment outcomes. Several mechanisms on how cellular distribution of LDL-derived cholesterol from LE/Lys influences cancer cell behavior are reviewed, some of those providing opportunities for treatment strategies to reduce cancer progression and anticancer drug resistance.

Overexpression of Lysosome-Associated Membrane Protein 1 in Oral Squamous Cell Carcinoma and its Correlation with Tumor Differentiation and Metastasis

INTRODUCTION

The overexpression of lysosome-associated membrane protein 1 (LAMP1) has been demonstrated in different types of cancers, such as ovarian carcinoma, esophageal squamous cell carcinoma, breast cancer, and colorectal carcinoma. Nonetheless, the expression of LAMP1 in oral squamous cell carcinoma (OSCC) has not been investigated yet.

MATERIALS AND METHODS

This cross-sectional study was conducted on 65 patients with OSCC selected from the Department of Pathology of Shiraz University of Medical Sciences. The control group comprised 55 tissues of normal oral epithelium. The expression of LAMP1 in OSCC tissue samples was assessed using immunohistochemistry (IHC) analysis. The association between LAMP1 and clinicopathological features of patients with OSCC was also evaluated.

RESULTS

The expression of LAMP1 was significantly higher in OSCC tissues, as compared to that in normal tissues (P<0.001). The chi-square analysis indicated that the high LAMP1 expression was correlated with the degree of tumor differentiation and metastasis (P=0.014).

CONCLUSIONS

The obtained results pointed to the overexpression of LAMP1 in OSCC, as well as its correlation with tumor grade and metastasis; therefore, LAMP1 might have a role to play in OSCC pathogenesis and could be regarded as an independent prognostic marker in oral squamous cell carcinoma.

The role of lysosomes in cancer development and progression

Lysosomes are an important component of the inner membrane system and participate in numerous cell biological processes, such as macromolecular degradation, antigen presentation, intracellular pathogen destruction, plasma membrane repair, exosome release, cell adhesion/migration and apoptosis. Thus, lysosomes play important roles in cellular activity. In addition, previous studies have shown that lysosomes may play important roles in cancer development and progression through the abovementioned biological processes and that the functional status and spatial distribution of lysosomes are closely related to cancer cell proliferation, energy metabolism, invasion and metastasis, immune escape and tumor-associated angiogenesis. Therefore, identifying the factors and mechanisms that regulate the functional status and spatial distribution of lysosomes and elucidating the relationship between lysosomes and the development and progression of cancer can provide important information for cancer diagnosis and prognosis prediction and may yield new therapeutic targets. This study briefly reviews the above information and explores the potential value of lysosomes in cancer therapy.

Transcriptomic Profiling for the Autophagy Pathway in Colorectal Cancer

The role of autophagy in colorectal cancer (CRC) pathogenesis appears to be crucial. Autophagy acts both as a tumor suppressor, by removing redundant cellular material, and a tumor-promoting factor, by providing access to components necessary for growth, metabolism, and proliferation. To date, little is known about the expression of genes that play a basal role in the autophagy in CRC. In this study, we aimed to compare the expression levels of 46 genes involved in the autophagy pathway between tumor-adjacent and tumor tissue, employing large RNA sequencing (RNA-seq) and microarray datasets. Additionally, we verified our results using data on 38 CRC cell lines. Gene set enrichment analysis revealed a significant deregulation of autophagy-related gene sets in CRC. The unsupervised clustering of tumors using the mRNA levels of autophagy-related genes revealed the existence of two major clusters: microsatellite instability (MSI)-enriched and -depleted. In cluster 1 (MSI-depleted), ATG9B and LAMP1 genes were the most prominently expressed, whereas cluster 2 (MSI-enriched) was characterized by DRAM1 upregulation. CRC cell lines were also clustered according to MSI-enriched/-depleted subgroups. The moderate deregulation of autophagy-related genes in cancer tissue, as compared to adjacent tissue, suggests a prominent field cancerization or early disruption of autophagy. Genes differentiating these clusters are promising candidates for CRC targeting therapy worthy of further investigation.

Chaperone-mediated autophagy receptor modulates tumor growth and chemoresistance in non-small cell lung cancer

Chaperone-mediated autophagy (CMA) is a lysosomal degradation pathway of selective soluble proteins. Lysosome-associated membrane protein type 2a (LAMP2A) is the key receptor protein of CMA; downregulation of LAMP2A leads to CMA blockade. Although CMA activation has been involved in cancer growth, CMA status and functions in non-small cell lung cancer (NSCLC) by focusing on the roles in regulating chemosensitivity remain to be clarified. In this study, we found that LAMP2A expression is elevated in NSCLC cell lines and patient's tumors, conferring poor survival and platinum resistance in NSCLC patients. LAMP2A knockdown in NSCLC cells suppressed cell proliferation and colony formation and increased the sensitivity to chemotherapeutic drugs in vitro. Furthermore, we found that intrinsic apoptosis signaling is the mechanism of cell death involved with CMA blockade. Remarkably, LAMP2A knockdown repressed tumorigenicity and sensitized the tumors to cisplatin treatment in NSCLC-bearing mice. Our discoveries suggest that LAMP2A is involved in the regulation of cancer malignant phenotypes and represents a promising new target against chemoresistant NSCLC.

Changes in the Oligodendrocyte Progenitor Cell Proteome with Ageing

Following central nervous system (CNS) demyelination, adult oligodendrocyte progenitor cells (OPCs) can differentiate into new myelin-forming oligodendrocytes in a regenerative process called remyelination. Although remyelination is very efficient in young adults, its efficiency declines progressively with ageing. Here we performed proteomic analysis of OPCs freshly isolated from the brains of neonate, young and aged female rats. Approximately 50% of the proteins are expressed at different levels in OPCs from neonates compared with their adult counterparts. The amount of myelin-associated proteins, and proteins associated with oxidative phosphorylation, inflammatory responses and actin cytoskeletal organization increased with age, whereas cholesterol-biosynthesis, transcription factors and cell cycle proteins decreased. Our experiments provide the first ageing OPC proteome, revealing the distinct features of OPCs at different ages. These studies provide new insights into why remyelination efficiency declines with ageing and potential roles for aged OPCs in other neurodegenerative diseases.

Lysosome as the Black Hole for Checkpoint Molecules

Lysosomes, as digestive organelles full of hydrolases, have complex functions and play an important role in cellular physiological and pathological processes. In normal physiological conditions, lysosomes can sense the nutritional state and be responsible for recycling raw materials to provide nutrients, affecting cell signaling pathways and regulating cell proliferation. Lysosomes are related to many diseases and associated with metastasis and drug resistance of tumors. In recent years, much attention has been paid to the tumor immunotherapy especially immune checkpoint blockade therapy. Accumulating data suggest that lysosomes may serve as a major destruction for immune checkpoint molecules, and secretory lysosomes can temporarily store immune checkpoint proteins. Once activated, the compounds contained in secretory lysosomes are released to the surface of cell membrane rapidly. Inhibitions of lysosomes can overcome the chemoresistance of some tumors and enhance the efficacy of immunotherapy.

Lysosome imaging in cancer cells by pyrene-benzothiazolium dyes: An alternative imaging approach for LAMP-1 expression based visualization methods to avoid background interference

A series of pyrene-benzothiazolium dyes (1a-1d) were experimentally investigated to study their internalization mechanism into cellular lysosomes as well as their potential imaging applications for live cell imaging. The lysosome selectivity of the probes was further compared by using fluorescently tagged lysosome associated membrane protein-1 (LAMP-1) expression-dependent visualization in both normal (COS-7, HEK293) and cancer (A549, Huh 7.5) cell lines. These probes were successfully employed as reliable lysosome markers in tumor cell models, thus providing an attractive alternative to LAMP-1 expression-dependent visualization methods. One advantage of these probes is the elimination of significant background fluorescence arising from fluorescently tagged protein expression on the cell surface when cells were transfected with LAMP-1 expression plasmids. Probes exhibited remarkable ability to stain cellular lysosomes for long-term experiments (up to 24 h) and the highly lipophilic nature of the probe design allowed their accumulation in hydrophobic regions of the cellular lysosomes. Experimental evidences indicated that the probes are likely to be internalized into lysosomes via endocytosis and accumulated in the hydrophobic regions of the lysosomes rather than in the acidic lysosomal lumen. These probes also demonstrated significant stability and lysosome staining for fixed cell imaging applications as well. Lastly, the benzothiazolium moiety of the probes was identified as the key component for lysosome selectivity.

Urine proteomics study reveals potential biomarkers for the differential diagnosis of cholangiocarcinoma and periductal fibrosis

Cholangiocarcinoma (CCA) is a primary malignant tumor of the epithelial lining of biliary track associated with endemic Opisthorchis viverrini (Ov) infection in northeastern Thailand. Ov-associated periductal fibrosis (PDF) is the precancerous lesion for CCA, and can be detected by ultrasonography (US) to facilitate early detection. However, US cannot be used to distinguish PDF from cancer. Therefore, the objective of this study was to discover and qualify potential urine biomarkers for CCA detection in at-risk population. Biomarker discovery was conducted on pooled urine samples, 42 patients per group, with PDF or normal bile duct confirmed by ultrasound. After depletion of high abundance proteins, 338 urinary proteins were identified from the 3 samples (normal-US, PDF-US, CCA). Based on fold change and literature review, 70 candidate proteins were selected for qualification by multiple reaction monitoring mass spectrometry (MRM-MS) in 90 individual urine samples, 30 per group. An orthogonal signal correction projection to latent structures discriminant analysis (O-PLS-DA) multivariate model constructed from the 70 candidate biomarkers significantly discriminated CCA from normal and PDF groups (P = 0.003). As an independent validation, the expression of 3 candidate proteins was confirmed by immunohistochemistry in CCA tissues: Lysosome associated membrane glycoprotein 1 (LAMP1), lysosome associated membrane glycoprotein 2 (LAMP2) and cadherin-related family member 2 (CDHR2). Further evaluation of these candidate biomarkers in a larger cohort is needed to support their applicability in a clinical setting for screening and monitoring early CCA and for CCA surveillance.

LAMP1 Overexpression Predicts for Poor Prognosis in Diffuse Large B-cell Lymphoma

INTRODUCTION

Lysosomal-associated membrane protein 1 (LAMP1) is a lysosomal and plasma membrane protein that contributes to tumor metastatic potential and differentiation.

PATIENTS AND METHODS

We performed immunohistochemical staining to investigate LAMP1 protein expression levels in 122 diffuse large B-cell lymphoma (DLBCL) tumor samples and 45 reactive hyperplasia tissues. Correlations between LAMP1 expression, various clinicopathologic features, and patient prognosis were evaluated by univariate and multivariate analyses.

RESULTS

LAMP1 expression was greater in the DLBCL tissues than in the reactive hyperplasia tissues. High LAMP1 expression was significantly associated with a high international prognostic index (score, 3-5; P = .023) and elevated lactate dehydrogenase level (P = .028). Moreover, high LAMP1 expression (P = .026), elevated serum lactate dehydrogenase level (P = .011), and high international prognostic index (P < .001) were independently associated with worse overall survival and progression-free survival.

CONCLUSION

These data provide the first evidence that LAMP1 expression is associated with a poor prognosis in patients with DLBCL.

Genes involved in the regulation of different types of autophagy and their participation in cancer pathogenesis

Autophagy is a highly conserved mechanism of self-digestion that removes damaged organelles and proteins from cells. Depending on the way the protein is delivered to the lysosome, four basic types of autophagy can be distinguished: macroautophagy, selective autophagy, chaperone-mediated autophagy and microautophagy. Macroautophagy involves formation of autophagosomes and is controlled by specific autophagy-related genes. The steps in macroautophagy are initiation, phagophore elongation, autophagosome maturation, autophagosome fusion with the lysosome, and proteolytic degradation of the contents. Selective autophagy is macroautophagy of a specific cellular component. This work focuses on mitophagy (selective autophagy of abnormal and damaged mitochondria), in which the main participating protein is PINK1 (phosphatase and tensin homolog-induced putative kinase 1). In chaperone-mediated autophagy, the substrate is bound to a heat shock protein 70 chaperone before it is delivered to the lysosome. The least characterized type of autophagy is microautophagy, which is the degradation of very small molecules without participation of an autophagosome. Autophagy can promote or inhibit tumor development, depending on the severity of the disease, the type of cancer, and the age of the patient. This paper describes the molecular basis of the different types of autophagy and their importance in cancer pathogenesis.

Fate of Antibody-Drug Conjugates in Cancer Cells

Antibody-Drug Conjugates (ADCs) are a class of cancer therapeutics that combines antigen specificity and potent cytotoxicity in a single molecule as they are comprised of an engineered antibody linked chemically to a cytotoxic drug. Four ADCs have received approval by the Food and Drug Administration (FDA) and the European Medicine Agency (EMA) and can be prescribed for metastatic conditions while around 60 ADCs are currently enrolled in clinical trials. The efficacy of an ADC greatly relies on its intracellular trafficking and processing of its components to trigger tumor cell death. A limited number of studies have addressed these critical processes that both challenge and help foster the design of ADCs. This review highlights those mechanisms and their relevance for future development of ADCs as cancer therapeutics.

Differential diagnosis of vacuolar muscle biopsies: use of p62, LC3 and LAMP2 immunohistochemistry

Intrafibral vacuoles are the morphological hallmark in a wide variety of human skeletal muscle disorders with different etiology. In most cases, differential diagnosis is feasible with a routine histochemical work up of muscle biopsy. Ultrastructural analysis is an important confirmatory tool, but it is not widely available. Immunohistochemical stainings for p62, LAMP2 and LC3 are commonly available as tissutal marker for autophagy. We compared the immunohistochemical patterns for autophagic markers p62, LC3 and LAMP2 with routine histochemical markers in 39 biopsies from patients with definite diagnoses of glycogen storage disease type 2 (LOPD or Pompe disease, PD), sporadic inclusion body myositis (sIBM), oculo-pharyngeal muscular dystrophy (OPMD) and necrotizing myopathy (NM). Moreover, we also analyzed muscles of 10 normal controls. In PD group, LC3 and LAMP2 showed an higher percentage of positive fibers, whereas p62 was limited to a minority of fibers, thus paralleling the results of histochemical stainings; in NM group, LAMP2 and LC-3 were diffusely and unspecifically expressed in necrotic fibers, with p62 significantly expressed only in two cases. OPMD biopsies did not reveal any significant positivity. The most interesting results were observed in sIBM group, where p62 was expressed in all cases, even in fibers without other markers positivity. There results, although limited to a small number of cases, suggest that the contemporary use of p62, LAMP2 and LC-3 staining may have an adjunctive role in characterizing muscle fiber vacuoles, revealing autophagic pathway activation and providing further clues for the understanding of pathogenetic mechanisms.s.

Cancer: Linking Powerhouses to Suicidal Bags

Membrane-bound organelles are integrated into cellular networks and work together for a common goal: regulating cell metabolism, cell signaling pathways, cell fate, cellular maintenance, and pathogen defense. Many of these interactions are well established, but little is known about the interplay between mitochondria and lysosomes, and their deregulation in cancer. The present review focuses on the common signaling pathways of both organelles, as well as the processes in which they both physically interact, their changes under pathological conditions, and the impact on targeting those organelles for treating cancer.

LAMP1 expression is associated with poor prognosis in breast cancer

Lysosome associated membrane protein-1 (LAMP1) is a heavily glycosylated lysosomal membrane protein, which is able to protect the lysosomal membrane from intracellular proteolysis. LAMP1 has been implicated in cancer development and progression. However, LAMP1 expression in breast cancer (BC) and its relationship with the clinical parameters of BC has not yet been fully investigated. In the present study, LAMP1 expression in BC was characterized by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) on 20 pairs of fresh-frozen BC and corresponding non-cancerous tissues. In addition, tissue microarray immunohistochemistry (TMA-IHC) was conducted on 143 BC and matched non-cancerous tissue samples. The results of RT-qPCR and TMA-IHC demonstrated that LAMP1 expression in BC tissues was significantly higher than in corresponding non-cancerous tissues. Furthermore, LAMP1 protein expression levels were significantly associated with histological grade (P=0.047), estrogen receptor expression (P=0.003), progesterone receptor expression (P=0.002), molecular classification (P=0.022), lymph node metastasis (P=0.033) and tumor-node-metastasis (TNM) stage (P=0.012). Multivariate analysis using Cox regression models and Kaplan-Meier survival curves demonstrated that LAMP1 expression (P=0.037), molecular classification (P=0.017) and TNM stage (P=0.003) were independent prognostic factors for overall survival. The above data suggested that LAMP1 expression is associated with malignant attributes of BC and may serve as a novel prognostic factor for patients with BC.

High expression of LAMP1 as a prognostic marker in patients with epithelial ovarian cancer

Lysosome Associated Membrane Protein-1 (LAMP1), expressed in several functional processes, is a heavily glycosylated lysosomal membrane protein which is able to protect the lysosomal membranes from intracellular proteolysis. Its pro-tumorigenic effects are involved in the development of several types of Malignancy. However, the role of LAMP1 in human Epithelial Ovarian Cancer (EOC) patients remains unclear. To demonstrate its prognostic significance in EOC, the methods of RT-PCR and IHC were used to evaluate LAMP1 expression in both EOC and nonmalignant tissues. What's more, the relationship between LAMP1 and clinicopathological factors was investigated. Survival analysis was used to elaborate its prognostic value. Expression of LAMP1 in tumor cells in EOC was significantly higher than those in noncancerous tissues. LAMP1 over-expression in EOC was significantly related to FIGO stage, metastasis invasion, positive ascites cell and the level of serum CA125. The Kaplan-Meier plot and Cox regression method have shown that LAMP1 over-expression in EOC and FIGO stage was significantly related to malignant features in EOC and EOC patients' unfavorable survival. It was strongly evidenced in our research that LAMP1 is a prognostic factor in EOC. Our results suggest that LAMP1 could be used as a poor prognostic factor and novel therapeutic target for EOC.

Polymorphisms of the coagulation system and risk of cancer

Hypercoagulability is a frequently finding in patients with cancer, and is associated with an increased risk of venous thrombosis (VT). Cancer-associated VT is associated with poor prognosis and represents the leading non-cancer cause of death among these patients. Conversely, patients experiencing VT are at increased risk of subsequent cancer, suggesting an epidemiological bidirectional link between cancer and hemostasis, and indicating a role of the hemostatic system in cancer development. How the coagulation system relates to cancer etiology at the genetic level is largely unexplored. Data on the association of polymorphisms in genes involved in coagulation with cancer development is important to clarify the role of the coagulation system in cancer pathogenesis. Effects of coagulation-related gene polymorphisms on cancer risk may possibly be translated into novel treatment- and prevention strategies of cancer-associated thrombosis and the cancer itself. This article reviews the current knowledge of the relation between polymorphisms in genes involved in coagulation and cancer risk in solid tumors.

Lysosomal Biology in Cancer

Cells depend on the lysosome for sequestration and degradation of macromolecules in order to maintain metabolic homeostasis. These membrane-enclosed organelles can receive intracellular and extracellular cargo through endocytosis, phagocytosis, and autophagy. Lysosomes establish acidic environments to activate enzymes that are able to break down biomolecules engulfed through these various pathways. Recent advances in methods to study the lysosome have allowed the discovery of extended roles for the lysosome in various diseases, including cancer, making it an attractive and targetable node for therapeutic intervention. This review focuses on key aspects of lysosomal biology in the context of cancer and how these properties can be exploited for the development of new therapeutic strategies. This will provide a contextual framework for how advances in methodology could be applied in future translational research.

Up-Regulated Expression of LAMP2 and Autophagy Activity during Neuroendocrine Differentiation of Prostate Cancer LNCaP Cells

Neuroendocrine (NE) prostate cancer (PCa) is a highly aggressive subtype of prostate cancer associated with resistance to androgen ablation therapy. In this study, we used LNCaP prostate cancer cells cultured in a serum-free medium for 6 days as a NE model of prostate cancer. Serum deprivation increased the expression of NE markers such as neuron-specific enolase (NSE) and βIII tubulin (βIII tub) and decreased the expression of the androgen receptor protein in LNCaP cells. Using cDNA microarrays, we compared gene expression profiles of NE cells and non-differentiated LNCaP cells. We identified up-regulation of 155 genes, among them LAMP2, a lysosomal membrane protein involved in lysosomal stability and autophagy. We then confirmed up-regulation of LAMP2 in NE cells by qRT-PCR, Western blot and confocal microscopy assays, showing that mRNA up-regulation correlated with increased levels of LAMP2 protein. Subsequently, we determined autophagy activity in NE cells by assessing the protein levels of SQSTM/p62 and LC3 by Western blot and LC3 and Atg5 mRNAs content by qRT-PCR. The decreased levels of SQSTM/p62 was accompanied by an enhanced expression of LC3 and ATG5, suggesting activation of autophagy in NE cells. Blockage of autophagy with 1μM AKT inhibitor IV, or by silencing Beclin 1 and Atg5, prevented NE cell differentiation, as revealed by decreased levels of the NE markers. In addition, AKT inhibitor IV as well as Beclin1 and Atg5 kwockdown attenuated LAMP2 expression in NE cells. On the other hand, LAMP2 knockdown by siRNA led to a marked blockage of autophagy, prevention of NE differentiation and decrease of cell survival. Taken together, these results suggest that LAMP2 overexpression assists NE differentiation of LNCaP cells induced by serum deprivation and facilitates autophagy activity in order to attain the NE phenotype and cell survival. LAMP2 could thus be a potential biomarker and potential target for NE prostate cancer.

Direct regulation of LAMP1 by tumor-suppressive microRNA-320a in prostate cancer

Advanced prostate cancer (PCa) metastasizes to bone and lymph nodes, and currently available treatments cannot prevent the progression and metastasis of the disease. Therefore, an improved understanding of the molecular mechanisms of the progression and metastasis of advanced PCa using current genomic approaches is needed. Our miRNA expression signature in castration-resistant prostate cancer (CRPC) revealed that microRNA-320a (miR‑320a) was significantly reduced in cancer tissues, suggesting that miR‑320a may be a promising anticancer miRNA. The aim of this study was to investigate the functional roles of miR‑320a in naïve PCa and CRPC cells and to identify miR‑320a-regulated genes involved in PCa metastasis. The expression levels of miR‑320a were significantly reduced in naïve PCa, CRPC specimens, and PCa cell lines. Restoration of mature miR‑320a in PCa cell lines showed that miR‑320a significantly inhibited cancer cell migration and invasion. Moreover, we found that lysosomal-associated membrane protein 1 (LAMP1) was a direct target of miR‑320a in PCa cells. Silencing of LAMP1 using siRNA significantly inhibited cell proliferation, migration, and invasion in PCa cells. Overexpression of LAMP1 was observed in PCa and CRPC clinical specimens. Moreover, downstream pathways were identified using si-LAMP1-transfected cells. The discovery of tumor-suppressive miR‑320a-mediated pathways may provide important insights into the potential mechanisms of PCa metastasis.

Targeting the lysosome in cancer

Lysosomes are membrane-bound intracellular organelles that receive macromolecules delivered by endocytosis, phagocytosis, and autophagy for degradation and recycling. Over the last decade, advances in lysosome research have established a broad role for the lysosome in the pathophysiology of disease. In this review, we highlight the recent discoveries in lysosome biology, with an emphasis on their implications for cancer therapy. We focus on targeting the lysosome in cancer by exploring lysosomal biogenesis and its role in the crosstalk between apoptosis and autophagy. We also discuss how lysosomal inhibition could emerge as a new therapeutic strategy to overcome drug resistance in cancer.

Epigenetic silencing of microRNA-373 to epithelial-mesenchymal transition in non-small cell lung cancer through IRAK2 and LAMP1 axes

The role of microRNAs (miRNAs) in carcinogenesis as tumor suppressors or oncogenes has been widely reported. Epigenetic change is one of the mechanisms of transcriptional silencing of miRNAs in cancer. To identify lung cancer-related miRNAs that are mediated by histone modification, we conducted microarray analysis in the Calu-6 non-small cell lung cancer (NSCLC) cell line after treatment with suberoylanilide hydroxamic acid (SAHA), a histone deacetylase (HDAC) inhibitor. The expression level of miR-373 was enhanced by SAHA treatment in this cell line by microarray and the following quantitative RT-PCR analyses. Treatment with another HDAC inhibitor, Trichostatin A, restored the levels of miR-373 expression in A549 and Calu-6 cells, while demethylation drug treatment did not. Importantly, miR-373 was found to be down-regulated in NSCLC tissues and cell lines. Transfection of miR-373 into A549 and Calu-6 cells attenuated cell proliferation, migration, and invasion and reduced the expression of mesenchymal markers. Additional microarray analysis of miR-373-transfected cells and computational predictions identified IRAK2 and LAMP1 as targets of miR-373. Knockdown of these two genes showed similar biological effects to those of miR-373 overexpression. In clinical samples, overexpression of IRAK2 correlated with decreased disease-free survival of patients with non-adenocarcinoma. In conclusion, we found that miR-373 is silenced by histone modification in lung cancer cells and identified its function as a tumor suppressor and negative regulator of the mesenchymal phenotype through downstream IRAK2 and LAMP1 target genes.

Expression of the lysosomal-associated membrane protein-1 (LAMP-1) in astrocytomas

Targeting of lysosomes is a novel therapeutic anti-cancer strategy for killing the otherwise apoptosis-resistant cancer cells. Such strategies are urgently needed for treatment of brain tumors, especially the glioblastoma, which is the most frequent and most malignant type. The aim of the present study was to investigate the presence of lysosomes in astrocytic brain tumors focussing also on the therapy resistant tumor stem cells. Expression of the lysosomal marker LAMP-1 (lysosomal-associated membrane protein-1) was investigated by immunohistochemistry in 112 formalin fixed paraffin embedded astrocytomas and compared with tumor grade and overall patient survival. Moreover, double immunofluorescence stainings were performed with LAMP-1 and the astrocytic marker GFAP and the putative stem cell marker CD133 on ten glioblastomas. Most tumors expressed the LAMP-1 protein in the cytoplasm of the tumor cells, while the blood vessels were positive in all tumors. The percentage of LAMP-1 positive tumor cells and staining intensities increased with tumor grade but variations in tumors of the same grade were also found. No association was found between LAMP-1 expression and patient overall survival in the individual tumor grades. LAMP-1/GFAP showed pronounced co-expression and LAMP-1/CD133 was co-expressed as well suggesting that tumor cells including the proposed tumor stem cells contain lysosomes. The results suggest that high amounts of lysosomes are present in glioblastomas and in the proposed tumor stem cells. Targeting of lysosomes may be a promising novel therapeutic strategy against this highly malignant neoplasm.

LAMP2A overexpression in breast tumors promotes cancer cell survival via chaperone-mediated autophagy

Lysosome-associated membrane protein type 2A (LAMP2A) is a key protein in the chaperone-mediated autophagy (CMA) pathway. LAMP2A helps in lysosomal uptake of modified and oxidatively damaged proteins directly into the lumen of lysosomes for degradation and protein turnover. Elevated expression of LAMP2A was observed in breast tumor tissues of all patients under investigation, suggesting a survival mechanism via CMA and LAMP2A. Reduced expression of the CMA substrates, GAPDH and PKM, was observed in most of the breast tumor tissues when compared with the normal adjacent tissues. Reactive oxygen species (ROS) mediated oxidative stress damages regulatory cellular components such as DNA, proteins and/or lipids. Protein carbonyl content (PCC) is widely used as a measure of total protein oxidation in cells. Ectopic expression of LAMP2A reduces PCC and thereby promotes cell survival during oxidative stress. Furthermore, inhibition of LAMP2A stimulates accumulation of GAPDH, AKT1 phosphorylation, generation of ROS, and induction of cellular apoptosis in breast cancer cells. Doxorubicin, which is a chemotherapeutic drug, often becomes ineffective against tumor cells with time due to chemotherapeutic resistance. Breast cancer cells deficient of LAMP2A demonstrate increased sensitivity to the drug. Thus, inhibiting CMA activity in breast tumor cells can be exploited as a potential therapeutic application in the treatment of breast cancer.

Regulation of apoptosis-associated lysosomal membrane permeabilization

Lysosomal membrane permeabilization (LMP) occurs in response to a large variety of cell death stimuli causing release of cathepsins from the lysosomal lumen into the cytosol where they participate in apoptosis signaling. In some settings, apoptosis induction is dependent on an early release of cathepsins, while under other circumstances LMP occurs late in the cell death process and contributes to amplification of the death signal. The mechanism underlying LMP is still incompletely understood; however, a growing body of evidence suggests that LMP may be governed by several distinct mechanisms that are likely engaged in a death stimulus- and cell-type-dependent fashion. In this review, factors contributing to permeabilization of the lysosomal membrane including reactive oxygen species, lysosomal membrane lipid composition, proteases, p53, and Bcl-2 family proteins, are described. Potential mechanisms to safeguard lysosomal integrity and confer resistance to lysosome-dependent cell death are also discussed.

Sensitization to the lysosomal cell death pathway by oncogene-induced down-regulation of lysosome-associated membrane proteins 1 and 2

Expression and activity of lysosomal cysteine cathepsins correlate with the metastatic capacity and aggressiveness of tumors. Here, we show that transformation of murine embryonic fibroblasts with v-H-ras or c-src(Y527F) changes the distribution, density, and ultrastructure of the lysosomes, decreases the levels of lysosome-associated membrane proteins (LAMP-1 and LAMP-2) in an extracellular signal-regulated kinase (ERK)- and cathepsin-dependent manner, and sensitizes the cells to lysosomal cell death pathways induced by various anticancer drugs (i.e., cisplatin, etoposide, doxorubicin, and siramesine). Importantly, K-ras and erbb2 elicit a similar ERK-mediated activation of cysteine cathepsins, cathepsin-dependent down-regulation of LAMPs, and increased drug sensitivity in human colon and breast carcinoma cells, respectively. Notably, reconstitution of LAMP levels by ectopic expression or by cathepsin inhibitors protects transformed cells against the lysosomal cell death pathway. Furthermore, knockdown of either lamp1 or lamp2 is sufficient to sensitize the cells to siramesine-induced cell death and photo-oxidation-induced lysosomal destabilization. Thus, the transformation-associated ERK-mediated up-regulation of cysteine cathepsin expression and activity leads to a decrease in the levels of LAMPs, which in turn contributes to the enhanced sensitivity of transformed cells to drugs that trigger lysosomal membrane permeabilization. These data indicate that aggressive cancers with high cysteine cathepsin levels are especially sensitive to lysosomal cell death pathways and encourage the further development of lysosome-targeting compounds for cancer therapy.

Proteome informatics for cancer research: from molecules to clinic

Proteomics offers the most direct approach to understand disease and its molecular biomarkers. Biomarkers denote the biological states of tissues, cells, or body fluids that are useful for disease detection and classification. Clinical proteomics is used for early disease detection, molecular diagnosis of disease, identification and formulation of therapies, and disease monitoring and prognostics. Bioinformatics tools are essential for converting raw proteomics data into knowledge and subsequently into useful applications. These tools are used for the collection, processing, analysis, and interpretation of the vast amounts of proteomics data. Management, analysis, and interpretation of large quantities of raw and processed data require a combination of various informatics technologies such as databases, sequence comparison, predictive models, and statistical tools. We have demonstrated the utility of bioinformatics in clinical proteomics through the analysis of the cancer antigen survivin and its suitability as a target for cancer immunotherapy.

LAMPs and ABH histo-blood group antigens in granulation tissue

Endothelial cells are major participants in angiogenic processes accompanying wound repair. The functions of ABH histo-blood group antigens (HBGAs) and lysosome-associated membrane proteins LAMP-1 and LAMP-2 in endothelial cells of granulation tissue are currently unkown. Here we hypothesize that HBGAs and LAMPs enrich the phenotypic characteristics of endothelial cells and might be implicated in the plasticity of granulation tissue. Immunohistochemistry revealed permanent expression of HBGAs in the cytoplasm of endothelial cells of all sprouting capillaries regardless of the organ examined. A modulation in both the localization and the intensity of the signal for LAMPs was observed. Interestingly, LAMP-1 showed a more intensive staining compared to LAMP-2. LAMP-1 was found in the cytoplasm, as well as on plasma membranes of endothelial cells. We present the first comparative immunohistochemical study of the expression of HBGA and LAMPs in endothelial cells of granulation tissue. Novel evidence for modulating LAMP reactivity is reported. Our results suggest that both glycoconjugates might contribute to the process of neoangiogenesis and tissue remodeling in wound healing.

Modulating expression of LAMPs and ABH histo-blood group antigens in normal and neoplastic human skin

Although the precise biological role of lysosomal membrane-associated glycoproteins (LAMPs) and ABH histo-blood group antigens (HBGAs) remains somewhat unclear, they are thought to be related to cell differentiation, cellular adhesion, and tumorigenesis. Here, we present the first comparative immunohistochemical study of both LAMPs and HBGAs in normal and neoplastic skin. Their localization is compared to that of high molecular weight cytokeratin and cytokeratin MNF 116. LAMPs and HBGA were differentially expressed in the normal stratified squamous epithelium, suggesting that they are involved in the initial steps of the differentiation process, whereas HBGAs are characteristic of terminal keratinocyte differentiation. No change in the reactivity for HBGA was detected in the stratified epithelium overlying squamous cell or basal cell carcinomas, whereas a considerable loss of LAMPs was detected. LAMPs were overexpressed in tumor cells, whereas HBGAs were lost in tumor zones of basocellular carcinomas. In spinocellular carcinomas, HBGAs were detected in tumor keratinocytes and in keratin pearls. These results provide new evidence for the differential expression of LAMPs and HBGAs in the normal stratified squamous epithelium, as well as the presence of a modulating reactivity in basocellular and spinocellular carcinomas, suggesting that these glycoproteins are involved in differentiation and tumorigenesis of human skin.

Different expression of lysosome-associated membrane protein-1 in human melanomas and benign melanocytic lesions

Lysosome-associated membrane protein-1 is a protein with a significant content of beta1,6-branched N-glycans. It is thought that enhanced expression of lysosome-associated membrane protein-1 in tumour cells may promote invasion by influencing both adhesion to extracellular matrix and perhaps also binding to endothelial cells. The present study was aimed at examining levels of lysosome-associated membrane protein-1 in human melanomas and benign pigmented lesions to evaluate whether this protein might be considered a potential molecular marker of melanoma progression. The expression of lysosome-associated membrane protein-1 was for the first time determined immunohistochemically in formalin-fixed paraffin-embedded specimens comprising 42 primary cutaneous melanomas, 15 lymph node melanoma metastases (11 correlated with primary tumours), three melanoma recurrences (correlated with both primary and metastatic melanomas), 27 nevi and four epithelial tumours (two seborrhoeic keratoses and two basal cell carcinomas). Our results demonstrate that development and progression of melanoma are associated with changes of the lysosome-associated membrane protein-1 level. The expression was strongest in melanoma recurrences and lymph node metastases, weaker in primary cutaneous melanomas and not detectable in melanocytes of pigmented nevi. Nodular melanomas expressed lysosome-associated membrane protein-1 at higher level than superficially spreading melanomas.

Development of MPS IVA mouse (Galnstm(hC79S.mC76S)slu) tolerant to human N-acetylgalactosamine-6-sulfate sulfatase

Mucopolysaccharidosis IVA (MPS IVA) is an autosomal recessive disease caused by N-acetylgalactosamine-6-sulfate sulfatase (GALNS) deficiency. In recent studies of enzyme replacement therapy for animal models with lysosomal storage diseases, cellular and humoral immune responses to the injected enzymes have been recognized as major impediments to effective treatment. To study the long-term effectiveness and side effects of therapies in the absence of immune responses, we have developed an MPS IVA mouse model, which has many similarities to human MPS IVA and is tolerant to human GALNS protein. We used a construct containing both a transgene (cDNA) expressing inactive human GALNS in intron 1 and an active site mutation (C76S) in adjacent exon 2 and thereby introduced both the inactive cDNA and the C76S mutation into the murine Galns by targeted mutagenesis. Affected homozygous mice have no detectable GALNS enzyme activity and accumulate glycosaminoglycans in multiple tissues including visceral organs, brain, cornea, bone, ligament and bone marrow. At 3 months, lysosomal storage is marked within hepatocytes, reticuloendothelial Kupffer cells, and cells of the sinusoidal lining of the spleen, neurons and meningeal cells. The bone storage is also obvious, with lysosomal distention in osteoblasts and osteocytes lining the cortical bone, in chondrocytes and in the sinus lining cells in bone marrow. Ubiquitous expression of the inactive human GALNS was also confirmed by western blot using the anti-GALNS monoclonal antibodies newly produced, which resulted in tolerance to immune challenge with human enzyme. The newly generated MPS IVA mouse model should provide a good model to evaluate long-term administration of enzyme replacement.

The potentials of MS-based subproteomic approaches in medical science: the case of lysosomes and breast cancer

Because of the great number of women who are diagnosed with breast cancer each year, and though this disease presents the lowest mortality rate among cancers, breast cancer remains a major public health problem. As for any cancer, the tumorigenic and metastatic processes are still hardly understood, and the biochemical markers that allow either a precise monitoring of the disease or the classification of the numerous forms of breast cancer remain too scarce. Therefore, great hopes are put on the development of high-throughput genomic and proteomic technologies. Such comprehensive techniques should help in understanding the processes and in defining steps of the disease by depicting specific genes or protein profiles. Because techniques dedicated to the current proteomic challenges are continuously improving, the probability of the discovery of new potential protein biomarkers is rapidly increasing. In addition, the identification of such markers should be eased by lowering the sample complexity; e.g., by sample fractionation, either according to specific physico-chemical properties of the proteins, or by focusing on definite subcellular compartments. In particular, proteins of the lysosomal compartment have been shown to be prone to alterations in their localization, expression, or post-translational modifications (PTMs) during the cancer process. Some of them, such as the aspartic protease cathepsin D (CatD), have even been proven as participating actively in the disease progression. The present review aims at giving an overview of the implication of the lysosome in breast cancer, and at showing how subproteomics and the constantly refining MS-based proteomic techniques may help in making breast cancer research progress, and thus, hopefully, in improving disease treatment.