Metastasis-associated Proteins Research Articles

Targeting proteomics to investigate metastasis-associated mitochondrial proteins

Mitochondria are essential organelles in eukaryotic cells and are responsible for regulating energy metabolism, ROS production, and cell survival. Recently, various cellular pathogeneses, including tumorigenesis and metastasis, have been reported to be associated with mitochondrial homeostasis. Consequently, exploiting the correlation between dysfunctional mitochondria and tumor progression has been implicated in the understanding of tumorigenesis, tumor metastasis, and chemoresistance, along with novel strategies to develop cancer therapeutics. To comprehensively understand the role of the mitochondria in cancer metastasis, it is necessary to resolve thousands of mitochondrial proteins and their post-translational modifications with high-throughput global assessments. We introduce mitochondrial proteomic strategies in this review and a discussion on their recent findings related to cancer metastasis. Additionally, the mitochondrial respiratory chain is believed to be a major site for ROS production, and elevated ROS is likely a key source to trigger dysfunctional mitochondria and impaired mitochondrial metabolism that subsequently contribute to the development of cancer progression. Equipment-based metabolomic analysis now allows the monitoring of disease progression and diagnosis. These newly emerging techniques, including proteomics, redox-proteomics, and metabolomics, are described in this review.

An optimized isolation of biotinylated cell surface proteins reveals novel players in cancer metastasis

Details of metastasis, the deadliest aspect of cancer, are unclear. Cell surface proteins play central roles in adhesive contacts between the tumor cell and the stroma during metastasis. We optimized a fast, small-scale isolation of biotinylated cell surface proteins to reveal novel metastasis-associated players from an isogenic pair of human MDA-MB-435 cancer cells with opposite metastatic phenotypes. Isolated proteins were trypsin digested and analyzed using LC-MS/MS followed by quantitation with the Progenesis LC-MS software. Sixteen proteins displayed over twofold expression differences between the metastatic and non-metastatic cells. Interestingly, overexpression of most of them (14/16) in the metastatic cells indicates a gain of novel surface protein profile as compared to the non-metastatic ones. All five validated, differentially expressed proteins showed higher expression in the metastatic cells in culture, and four of these were further validated in vivo. Moreover, we analyzed expression of two of the identified proteins, CD109 and ITGA6 in 3-dimensional cultures of six melanoma cell lines. Both proteins marked the surface of cells derived from melanoma metastasis over cells derived from primary melanoma. The unbiased identification and validation of both known and novel metastasis-associated proteins indicate a reliable approach for the identification of differentially expressed surface proteins.

Abstract 3394: Identification of PRDX4 and P4HA2 as metastasis-associated proteins in oral cavity squamous cell carcinoma by comparative tissue proteomics of microdissected specimens using iTRAQ technology

Abstract Background Cervical lymph node metastasis represents the major prognosticator for oral cavity squamous cell carcinoma (OSCC). Methods Here, we used an iTRAQ-based quantitative proteomic approach to identify proteins that are differentially expressed between microdissected primary and metastatic OSCC tumors. The selected candidates were examined in tissue sections via immunohistochemistry, and their roles in OSCC cell function investigated using RNA interference. Results Seventy-four differentially expressed proteins in nodal metastases, including PRDX4 and P4HA2, were identified. Immunohistochemical analysis revealed significantly higher levels of PRDX4 and P4HA2 in tumor cells than adjacent non-tumor epithelia (P < 0.0001 and P < 0.0001, respectively), and even higher expression in the 31 metastatic tumors of lymph nodes, compared to the corresponding primary tumors (P = 0.060 and P < 0.0001, respectively). Overexpression of PRDX4 and P4HA2 was significantly associated with positive pN status (P = 0.048 and P = 0.041, respectively). PRDX4 overexpression was a significant prognostic factor for disease-specific survival in both univariate and multivariate analyses (P = 0.034 and P = 0.032, respectively). Additionally, cell migration and invasiveness were attenuated in OEC-M1 cells upon in vitro knockdown of PRDX4 and P4HA2 with specific interfering RNA. Conclusions Novel metastasis-related prognostic markers for OSCC could be identified by our approach. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3394. doi:1538-7445.AM2012-3394

Abstract LB-417: Identification of calreticulin as an invasion-associated protein in ovarian cancer by proteomic approach.

Abstract Ovarian cancer is the most lethal gynecological cancer among women worldwide. The majority of malignant ovarian tumors are epithelial ovarian cancer and metastasis has occurred in most patients at the time of diagnosis with worse outcome. In our previous study, we have established an ovarian endometrioid carcinoma cell line OVTW59. The original lines were designated as P0, and the highly invasive subline P4 was isolated from 4 rounds of invasion selection. By cDNA microarray analysis and further functional analysis, we have reported insulin-like growth factor binding protein-3 (IGFBP-3) as an invasion suppressor gene that correlated with poor patient survival outcome. In this study, we compared the protein profiles between OVTW59 P0 and P4 using 2D-electrophoresis to select metastasis-associated proteins. The potential candidates were subsequently analyzed by LC-MS/MS. We identified 49 positive invasion-associated proteins and 20 negative invasion-associated proteins. Gene-Ontology analysis showed that more than 50% of these proteins were invasion-related proteins. We then built up a potential network involving these differentially expressed proteins by Ingenuity Pathway Analysis. From these data, we selected Calreticulin for further analysis. Calreticulin has been reported in associated with cell adhesion, apoptosis, wound healing, removal of cancer cells, and autoimmune. By q-RT-PCR, Western blot and scratch test, we found Calreticulin positively associated with cancer invasion in our in-vitro system. In addition, higher Calreticulin expression was found in SCID mice with higher metastasitc capability. Clinically, immunohistochemical staining in 58 cases of ovarian endometiroid cancer will be performed. The result will be further correlated with patient outcome. In this study, we found Calreticulin a novel invasion-associated protein in ovarian endometrioid cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-417. doi:1538-7445.AM2012-LB-417

Comparative serum proteomic analysis involving liver organ-specific metastasis-associated proteins of nasopharyngeal carcinoma

Metastasis is the main cause of cancer-related mortality; patients with liver metastases (LM) have the worst prognosis among patients with nasopharyngeal carcinoma (NPC). However, at present, few biomarkers for detecting organ-specific metastasis have been identified. Proteomics, an ultra-sensitive analytical technique, can detect molecular changes before organ-specific metastasis occurs. Analysis with matrix-assisted, laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF-MS), combined with magnetic chemical affinity beads is a new technique for evaluating protein separation. We sought to identify potential liver-specific, metastasis-associated proteomic printing in patients with NPC. We examined 64 serum samples from 50 patients who had pathologically confirmed NPC and 14 who had pathologically confirmed non-NPC with LM using MALDI-TOF-MS with weak cation bead protein chips. During follow-up of at least 37 months (maximum, 176 months) following radiotherapy, we confirmed 16 cases of LM (LM NPC), 16 cases without LM (non-LM NPC) and 18 cases without metastasis (non-M NPC). Using comparison analysis, 4 protein mass peaks, 4155.34, 4194.87, 4210.78 and 4249.56 m/z were identified as liver-specific, metastasis-associated protein peaks in NPC and two of them (4155 and 4249 m/z) met two different statistical criteria in both ClinProt software analyses and discriminant analyses. Models based on the 4 potential serum markers of NPC discriminated between LM NPC, non-LM NPC, non-M NPC and non-NPC LM analyzed with sieved markers. The recognition capability and cross-validation of these models for differentiating the above 4 groups are all approximately 80%. MALDI-TOF-MS combined with tree analysis models may provide a clinical diagnostic platform for detecting potential liver-specific, metastasis-associated proteomic printing in NPC. However, markedly differential proteins still need to be identified.

Proteomics research of early metastasis-associated proteins in sentinel lymph nodes of colorectal cancer

Objective To investigate the early metastasis-associated proteins in sentinel lymph node (SLN) of colorectal cancer.Methods SLN and normal lymph nodes (NLN) were collected from forty-three cases.Hydrophobic protein samples were extracted from individual-matched NLN and SLN of colorectal cancer.Differentially expressed protein spots were detected by two-dimensional electrophoresis and image analysis,and subsequently identified by matrix assisted laser desorption/ionization-time of flight mass spectrometry-mass spectrometry (MALDI-TOF-MS).Metastasis-concerned proteins were selected for further study by western blotting and immunohistochemistry staining.Results Forty proteins were differentially expressed between NLN and SLN,and 4 metastasis-concerned proteins highly expressed in SLN were identified to be hnRNP A1,Ezrin,tubulin β-2C and Annexin A1.Significant difference for these 4 proteins between NLN and SLN was confirmed by western blotting and immunohistochemistry staining.Conclusion Different proteins ware expressed between NLN and SLN.Increased expression of hnRNP A1,Ezrin,tubulin β-2C and Annexin A1 in SLN suggests a significantly elevated early colorectal cancer metastasis Key words: Colorectal cancer; Sentinel lymph nodes; Proteomics

Metastasis-Associated Cell Surface Oncoproteomics

Oncoproteomics aims to the discovery of molecular markers, drug targets, and pathways by studying cancer specific protein expression, localization, modification, and interaction. Cell surface proteins play a central role in several pathological conditions, including cancer and its metastatic spread. However, cell surface proteins are underrepresented in proteomics analyses performed from the whole cell extracts due to their hydrophobicity and low abundance. Different methods have been developed to enrich and isolate the cell surface proteins to reduce sample complexity. Despite the method selected, the primary difficulty encountered is the solubilization of the hydrophobic transmembrane proteins from the lipid bilayer. This review focuses on proteomic analyses of metastasis-associated proteins identified using the cell surface biotinylation method. Interestingly, also certain intracellular proteins were identified from the cell surface samples. The function of these proteins at the cell surface might well differ from their function inside the cell.

MTA1 of the MTA (metastasis-associated) gene family and its encoded proteins: molecular and regulatory functions and role in human cancer progression

MTA1 (a metastasis-associated gene) is a newly discovere d human gene (residing on chromsome 14q32.3) that belongs to a family of cancer progression-related genes ( MTA ). The mRNA product of MTA1 along with its protein product MTA1 have been reported to be over-expressed in a wide variety of animal and human tumors. For example, the expression of MTA1 and its encoded protein MTA1 correlates with the malignant properties of many human cancers, including cancers of the breast, colon, stomach, li ver, prostate and others. The MTA proteins have bee n shown to be ubiquitinated transcriptional co-repressors that fu nction in histone deacetylation and are part of the NuRD complex, a nucleosome remodeling and histone deacetylating complex whose stability appears to be regulated by ubi quitinated MTA1 binding to E3 ubiquitin ligase constitutive ph otomorphogenesis protein-1 (COP1). The MTA1 protein plays an essential role in c-MYC-mediated cell transformatio n, and its expression correlates with mammary gland tumor formation. In the latter, MTA1 helps convert mammary cells to more aggressive phenotypes by repression of the estrogen receptor (ER) via trans-activation through deacetylation of chromatin in the ER-responsive el ement of ERresponsive genes. Another member of the MTA family, MTA3, is induced by estrogen and represses the exp ression of the transcriptional repressor Snail, a master regul ator of epithelial to mesenchymal transformation, r esulting in the expression of the cell adhesion molecule E-cadherin and maintenance of a differentiated, normal epithel ial phenotype in mammary cells. An important activity mediated by both MTA1 and MTA2 is deacylation and inactivation of tumor suppressor p53protein, in part by controlling its s tability by inhibiting ubiquitination, leading to i nhibition of growth arrest and apoptosis. Another factor deacetylated a nd stabilized by MTA1 NuRD complex is hypoxia-inducible factor1α (HIF-1α), which is involved in angiogenesis. Therefore, th e MTA proteins represent a possible set of master c oregulatory molecules involved in the carcinogenesis and progression of various malignant tumors. As su ch, they could be important new tools for cancer diagnosis and tre atment.

Primary Study of Lymph Node Metastasis‐Related Serum Biomarkers in Breast Cancer

The aim of this study was to detect the pretreatment serum protein profiles of breast cancer patients by mass spectrometry (MS) to screen candidate tumor biomarkers, which will supply a simple, accurate, and minimally invasive method to predict the axillary lymph node metastasis of breast cancer. We used magnetic bead-based weak cation-exchange chromatography followed by matrix-assisted laser desorption and ionization time-of-flight MS to detect proteins in the sera of 54 cases of axillary node-negative breast cancer, 47 cases of axillary node-positive breast cancer, and 101 healthy controls. The protein profiles were analyzed to screen tumor biomarkers and lymph node metastasis-associated proteins to establish and verify a diagnostic model. Comparison of the protein profiles between the two cancer groups resulted in a total of 111 discriminate m/z peaks that were associated with breast cancer. Furthermore, 40 discriminate m/z peaks were detected between breast cancer patients with and without axillary node metastases. Four protein m/z peaks at 5,643, 4,651, 2,377, and 2,240 were used to construct a diagnosis model, and cross-validation indicated that breast cancer with and without axillary node metastasis was identified with 87.04% sensitivity (47/54), 87.23% specificity (41/47), and 87.13% accuracy (88/101). These proteins could potentially be used as predictive biomarkers to distinguish between breast cancer patients with or without lymph node metastasis.

Identification of PRDX4 and P4HA2 as Metastasis-Associated Proteins in Oral Cavity Squamous Cell Carcinoma by Comparative Tissue Proteomics of Microdissected Specimens Using iTRAQ Technology

Cervical lymph node metastasis represents the major prognosticator for oral cavity squamous cell carcinoma (OSCC). Here, we used an iTRAQ-based quantitative proteomic approach to identify proteins that are differentially expressed between microdissected primary and metastatic OSCC tumors. The selected candidates were examined in tissue sections via immunohistochemistry, and their roles in OSCC cell function investigated using RNA interference. Seventy-four differentially expressed proteins in nodal metastases, including PRDX4 and P4HA2, were identified. Immunohistochemical analysis revealed significantly higher levels of PRDX4 and P4HA2 in tumor cells than adjacent non-tumor epithelia (P < 0.0001 and P < 0.0001, respectively), and even higher expression in the 31 metastatic tumors of lymph nodes, compared to the corresponding primary tumors (P = 0.060 and P = 0.002, respectively). Overexpression of PRDX4 and P4HA2 was significantly associated with positive pN status (P = 0.048 and P = 0.021, respectively). PRDX4 overexpression was a significant prognostic factor for disease-specific survival in both univariate and multivariate analyses (P = 0.034 and P = 0.032, respectively). Additionally, cell migration and invasiveness were attenuated in OEC-M1 cells upon in vitro knockdown of PRDX4 and P4HA2 with specific interfering RNA. Novel metastasis-related prognostic markers for OSCC could be identified by our approach.

B7‐H3 contributes to the metastatic capacity of melanoma cells by modulation of known metastasis‐associated genes

B7-H3, an immunoregulatory protein, is known to play a role in tumor progression. In many cancer types, observed correlations between high B7-H3 expression and poor prognosis have been attributed to involvement in antitumor immunity. However, here we demonstrate a nonimmunological alternative function of B7-H3 in cancer metastasis. Since advanced malignant melanoma is a disease with a poor survival rate and a broad pattern of metastasis, we used this disease as a model in our studies. We found that shRNA silencing of B7-H3 reduced the in vitro migratory potential and matrigel invasiveness of MDA-MB-435 and FEMX-I melanoma cells. In an experimental metastasis model in vivo, B7-H3 silencing of MDA-MB-435 cells resulted in reduced metastatic capacity and significantly increased the median symptom-free survival of nude mice (147 vs. 65 days, p < 0.001) and rats (53 vs. 42 days, p = 0.025) injected with MDA-MB-435 cells. Furthermore, a smaller fraction of mice had microscopically detectable metastases compared to control animals, and the pattern of metastases was slightly different between the two groups but with the brain as the predominant organ. Immunohistochemistry on samples from two melanoma patients showed strong B7-H3 staining in both a primary tumor and metastases. Notably, the metastasis-associated proteins, matrix metalloproteinase (MMP)-2, signal transducer and activator of transcription 3 (Stat3), and the level of secreted interleukin-8 (IL-8) were reduced in the B7-H3 knock-down cell variants, whereas tissue inhibitor of metalloproteinase (TIMP)-1 and-2 levels were increased. Taken together, our findings indicate a novel role for B7-H3 in the regulation of the metastatic capacity of melanoma cells and it might be a potential therapeutic target for anti-metastasis therapy.

Subcellular proteomics: Determination of specific location and expression levels of lymphatic metastasis associated proteins in hepatocellular carcinoma by subcellular fractionation

Background Subcellular fractionation and proteomics form an ideal partnership when it comes to specific location and analysis of intracellular organelles and expression levels of multiprotein complexes. Lymphatic metastasis is the major complicated system involving multiple factors. However, to date lymphatic metastatic mechanism is poorly understood. Aim To specifically locate expression site by subcellular fractionation, based on expression levels, interpret the involvement of different lymphatic metastasis associated proteins in hepatocellular carcinoma cell lines with different lymphatic metastasis potential. Method Mouse hepatocellular cell lines Hca-F and Hca-P are used to evaluate the location and expression levels of some lymphatic metastasis-associated proteins in the cell by using subcellular fractionation kit and Western blot analysis. The proteins under studies were Gelsolin, JNK and Annexin 7. Results Gelsolin was sequestered in cytoplasm, membrane and cytoskeleton in F-cells but in P-cells, it was found in cytoplasm and cytoskeleton .JNK was located in nuclear fraction and cytoskeleton in F and P cells, Annexin7 was in cytoplasm with its two isoforms only at this location, cell membrane and cytoskeleton in F and P cells. With the high expression level of Gelsolin, JNK and Annexin 7 in Hca-F cell line than Hca-P cell line. Conclusion With subcellular fractionation specific location of Gelsolin, JNK and Annexin 7 at various cell sites during lymphatic metastasis were determined. High expression levels were found in high lymphatic metastasis potential cell lines which indicate their roles according to different expression sites in the disease.

Expression and significance of metastasis-associated proteins in bladder cancer cells RT4 and 253J

Objective To detect the expression of metastasis-associated proteins in bladder cancer cells RT4 and 253J and explore the molecular mechanisms of malignant transition of bladder cancer. Methods The expression of E-cadherin and Vimentin in RT4 and 253J cells was detected by Western blotting.Millicell polycarbonate filter was used to analyze the invasive potency of RT4 and 253J cells. Results E-cadherin was detected with high expression in RT4 cells, whereas a very low expression in 253J cells:Vimentin was not detected in RT4 cells, but a high expression in 253J cells. Conclusion There was remarkable difference in the expressions of E-cadherin and Vimentin in RT4 and 253J cells, and there was different invasion characteristic in these two cell liness. E-cadherin and Vimentin play a key role in the malignant transition of bladder tumor. Key words: Bladder cancer; E-cadherin; Vimentin; Invasion

The novel lupus antigen related protein acheron enhances the development of human breast cancer

Acheron (Achn) is a new member of the Lupus antigen family of RNA binding proteins. Previous studies have shown that Achn controls developmental decisions in neurons and muscle. In the human mammary gland, Achn expression is restricted to ductal myoepithelial cells. Microarray analysis and immunohistochemistry have shown that Achn expression is elevated in some basal-like ductal carcinomas. To study the possible role of Achn in breast cancer, we engineered human MDA-MB-231 cells to stably express enhanced green fluorescent protein-tagged wild-type Achn (AchnWT), as well as Achn lacking either its nuclear localization signal (AchnNLS) or its nuclear export signal (AchnNES). In in vitro assays, AchnWT and AchnNES, but not AchnNLS, enhanced cell proliferation, lamellipodia formation, and invasive activity and drove expression of the elevated expression of the metastasis-associated proteins MMP-9 and VEGF. To determine if Achn could alter the behavior of human breast cancer cells in vivo, Achn-engineered MDA-MB-231 cells were injected into athymic SCID/Beige mice. AchnWT and AchnNES-expressing tumors displayed enhanced angiogenesis and an approximately 5-fold increase in tumor size relative to either control cells or those expressing AchnNLS. These data suggest that Achn enhances human breast tumor growth and vascularization and that this activity is dependent on nuclear localization.

Abstract 2423: B7-H3 contributes to increased metastatic potential of melanoma cells by interfering with the expression of metastasis-related genes

Abstract Metastatic malignant melanoma is a disease with a long time survival rate of only 5%. Since there is no effective treatment for advanced melanoma, detection of molecular markers involved in tumor progression and drug resistance can hopefully provide new insight in therapeutically aspects of this disease. We have been studying B7-H3 – a glycosylated transmembrane protein which has been shown to play a role in cancer progression through its immunoregulatory properties. B7-H3 is highly expressed in melanoma cell lines as well as in clinical melanoma specimens, and we have previously demonstrated a role of the protein in chemoresistance. Thus, in this study, we wanted to investigate the possible function of B7-H3 in melanoma metastasis development. We found that short hairpin RNA silencing of B7-H3 reduced the migratory potential as well as the matrigel-invasiveness of the malignant melanoma cells in vitro. In an in vivo experimental metastasis model, silencing of B7-H3 increased the symptom-free survival of nude mice and rats significantly, this in parallel with a lower fraction mice having microscopically detectable metastasis compared to control mice. The brain was the predominant organ with metastases and a clear difference between the nude mice injected with B7-H3 expressing cells and B7-H3 knock down cells was observed, with 10/14 and 6/17 mice having brain tumors, respectively. Furthermore, we found the expression of several metastasis-associated proteins, such as MMP-2, TIMP1 and TIMP2 to be regulated by B7-H3. In addition, the secretion of IL-8 was markedly reduced in the B7-H3 knock down cells as well as the phosphorylation of Stat3. Interestingly, activated Stat3 is known to play a role in brain metastasis. Taken together, our findings suggest that B7-H3 might be a potential therapeutic target for anti-metastasis therapy in human melanoma. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2423. doi:10.1158/1538-7445.AM2011-2423

Quantitative Secretome Analysis Reveals that COL6A1 is a Metastasis-Associated Protein Using Stacking Gel-Aided Purification Combined with iTRAQ Labeling

In cancer metastasis, secreted proteins play an important role in promoting cancer cell migration and invasion and thus also in the increase of cancer metastasis in the extracellular microenvironment. In this study, we developed a strategy that combined a simple gel-aided protein purification with iTRAQ labeling to quantify and discover the metastasis-associated proteins in the lung cancer cell secretome. Secreted proteins associated with lung cancer metastasis were produced using CL1-0 and CL1-5 cells with different metastatic abilities. Quantitative secretomics analysis identified a total of 353 proteins, 7 of which were considered to be metastasis-associated proteins. These included TIMP1, COL6A1, uPA, and AAT, all of which were higher in CL1-5, and AL1A1, PRDX1, and NID1, which were higher in CL1-0. Six of these metastasis-associated proteins were validated with Western blot analysis. In addition, pathway analysis was performed in building the interaction network between the identified metastasis-associated proteins. Further functional analysis of COL6A1 on the metastatic abilities of CL1 cells was also carried out. An RNA interference-based knock-down of COL6A1 suppressed the metastatic ability of CL1-5 cells; in contrast, a plasmid-transfected overexpression of COL6A1 increased the metastatic ability of CL1-0 cells. This study describes a simple and high throughput sample purification method that can be used for the quantitative secretomics analysis of metastasis-associated proteins.

Systematic proteomic analysis of human hepotacellular carcinoma cells reveals molecular pathways and networks involved in metastasis

Systematic proteomic studying of the mechanism of hepatocellular carcinoma (HCC) metastasis remains challenging. We performed comparative proteomic and pathway analysis of four human metastatic HCC cell lines to identify metastasis-associated proteins. These HCC cell lines had a similar genetic background but with an increasing potential of metastasis. Using a combination of two dimensional electrophoresis (2-DE) and MALDI-TOF mass spectrometry, a total of 125 proteins and their post-translational modification forms or isoforms were found to be differentially expressed in the cell lines. Among them, 29 were gradually up-regulated whereas 17 were down-regulated with increasing metastatic potential. Instead of a traditional single-gene readout, global bioinformatics analysis was carried out, which revealed that the glycolysis pathway was the most significantly enriched pathway. The heat shock proteins (HSPs) centered and NF-kappaB centered networks were also enriched in the result, which may imply the key function of inflaming on metastasis. Meanwhile, knockdown of HDGF, an up-regulated protein and a target of NF-kappaB, induced cell apoptosis in the metastatic HCC cells. This work provides a demonstration that a combination of bioinformatics and comparative proteomics can help in finding out potential biomarkers associated with HCC metastasis on the level of pathways.

Cathepsin S Mediates Gastric Cancer Cell Migration and Invasion via a Putative Network of Metastasis-Associated Proteins

Cathepsin S Mediates Gastric Cancer Cell Migration and Invasion via a Putative Network of Metastasis-Associated Proteins

Cathepsin S Mediates Gastric Cancer Cell Migration and Invasion via a Putative Network of Metastasis-Associated Proteins

Cancer progression is governed by multifaceted interactions of cancer cells with their microenvironment and one of these ways is through secreted compounds. Substances released by gastric cancer cells have not being profiled in a proteome-wide manner. ITRAQ-based tandem mass spectrometry was employed to quantify proteins secreted by HFE145 normal, MKN7 well-differentiated, and MKN45 poorly differentiated gastric cancer cell lines. The expression levels of 237 proteins were found to be significantly different between normal and cancer cells. Further examination of 16 gastric cell lines and 115 clinical samples validated the up-regulation of CTSS expression in gastric cancer. Silencing CTSS expression suppressed the migration and invasion of gastric cancer cells in vitro. Subsequent secretomics revealed that CTSS silencing resulted in changes in expression levels of 197 proteins, one-third of which are implicated in cellular movement. Proteome-wide comparative secretomes of normal and gastric cancer cells were produced that constitute a useful resource for gastric cancer research. CTSS was demonstrated to play novel roles in gastric cancer cell migration and invasion, putatively via a network of proteins associated with cell migration, invasion, or metastasis. Cathepsin S is member of a large group of extracellular proteases, which are attractive drug targets. The implicated role of CTSS in gastric cancer metastasis provides an opportunity to test existing compounds against CTSS for adjuvant therapy and/or treatment of metastatic gastric cancers.

Expression profiling identifies new function of collapsin response mediator protein 4 as a metastasis-suppressor in prostate cancer

Metastasis is the chief cause of mortality from cancer, but the mechanisms leading to metastasis are poorly understood. We used a proteomics approach to screen for metastasis-associated proteins and found that collapsin response mediator protein-4 (CRMP4) expression was inversely associated with the lymph node metastasis of prostate cancer (PCa). Subsequent in vitro and in vivo studies revealed that overexpression of CRMP4 not only suppressed the invasion ability of PCa cells, but also strongly inhibited tumor metastasis in an animal model. Furthermore, methylation of a CpG island within the promoter region of the CRMP4 gene is responsible for downregulation of CRMP4 expression. Thus, in this study, we show new function of CRMP4 as a metastasis-suppressor in PCa. The findings provide new mechanistic insights into metastasis and therapeutic potential for this most common male cancer.