Comparative proteomic analysis of matched primary and metastatic melanoma cell lines

Secreted cyclophilin A is non-genotoxic but acts as a tumor promoter

Chronic inflammation is associated with malignant transformation and creates the microenvironment for tumor progression. Cyclophilin A (CypA) is one of the major pro-inflammatory mediators that accumulates and persists in the site of inflammation in high doses over time. According to multiomics analyses of transformed cells, CypA is widely recognized as a pro-oncogenic factor. Vast experimental data define the functions of intracellular CypA in carcinogenesis, but findings on the role of its secreted form in tumor formation and progression are scarce. In the studies here, we exploit short-term in vitro and in vivo tests to directly evaluate the mutagenic, recombinogenic, and blastomogenic effects, as well as the promoter activity of recombinant human CypA (rhCypA), an analogue of secreted CypA. Our findings showed that rhCypA had no genotoxicity and, thus, was neither involved in nor influenced the initiation stage of carcinogenesis. At high doses, rhCypA could disrupt gap junctions in rat liver epithelial IAR-2 cells in vitro by decreasing the expression of connexins 26 and 43 in these cells and inhibit A549 cell adhesion. These data suggested that rhCypA could contribute to epithelial-mesenchymal transition in malignant cells. The research presented here elucidated the role of secreted CypA in carcinogenesis, revealing that it is not a tumor initiator but can act as a tumor promoter at high concentrations.

Dose and Sequence Dependent Synergism from the Combination of Oxaliplatin with Emetine and Patulin Against Colorectal Cancer

BACKGROUND

Colorectal cancer is the third most commonly diagnosed cancer in the world, causing many deaths every year. Combined chemotherapy has opened a new horizon in treating colorectal cancer. The objective of the present study is to investigate the activity of oxaliplatin in combination with emetine and patulin against colorectal cancer models.

METHODS

IC50 values of oxaliplatin, emetine and patulin were determined against human colorectal cancer cell lines (HT-29 and Caco-2) using MTT reduction assay. Synergistic, antagonistic and additive effects from the selected binary combinations were determined as a factor of sequence of administration and added concentrations. Proteomics was carried out to identify the proteins which were accountable for combined drug action applying to the selected drug combination.

RESULTS

Oxaliplatin in combination with patulin produced synergism against human colorectal cancer models depending on dose and sequence of drug administration. Bolus administration of oxaliplatin with patulin proved to be the best in terms of synergistic outcome. Altered expressions of nine proteins (ACTG, PROF1, PPIA, PDIA3, COF1, GSTP1, ALDOA, TBA1C and TBB5) were considered for combined drug actions of oxaliplatin with patulin.

CONCLUSION

Bolus administration of oxaliplatin with patulin has the potential to be used in the treatment of colorectal cancer, and would warrant further evaluation using suitable animal model.

Mass Spectrometry-Based Proteomic Characterization of Cutaneous Melanoma Ectosomes Reveals the Presence of Cancer-Related Molecules

Cutaneous melanoma (CM) is an aggressive type of skin cancer for which effective biomarkers are still needed. Recently, the protein content of extracellular vesicles (ectosomes and exosomes) became increasingly investigated in terms of its functional role in CM and as a source of novel biomarkers; however, the data concerning the proteome of CM-derived ectosomes is very limited. We used the shotgun nanoLC-MS/MS approach to the profile protein content of ectosomes from primary (WM115, WM793) and metastatic (WM266-4, WM1205Lu) CM cell lines. Additionally, the effect exerted by CM ectosomes on recipient cells was assessed in terms of cell proliferation (Alamar Blue assay) and migratory properties (wound healing assay). All cell lines secreted heterogeneous populations of ectosomes enriched in the common set of proteins. A total of 1507 unique proteins were identified, with many of them involved in cancer cell proliferation, migration, escape from apoptosis, epithelial-mesenchymal transition and angiogenesis. Isolated ectosomes increased proliferation and motility of recipient cells, likely due to the ectosomal transfer of different cancer-promoting molecules. Taken together, these results confirm the significant role of ectosomes in several biological processes leading to CM development and progression, and might be used as a starting point for further studies exploring their diagnostic and prognostic potential.

Cyclophilin A Inhibitor Debio-025 Targets Crk, Reduces Metastasis, and Induces Tumor Immunogenicity in Breast Cancer

The Crk adaptor protein, a critical modifier of multiple signaling pathways, is overexpressed in many cancers where it contributes to tumor progression and metastasis. Recently, we have shown that Crk interacts with the peptidyl prolyl cis-trans isomerase, Cyclophilin A (CypA; PP1A) via a G²¹⁹P²²⁰Y²²¹ (GPY) motif in the carboxyl-terminal linker region of Crk, thereby delaying pY221 phosphorylation and preventing downregulation of Crk signaling. Here, we investigate the physiologic significance of the CypA/Crk interaction and query whether CypA inhibition affects Crk signaling in vitro and in vivo. We show that CypA, when induced under conditions of hypoxia, regulates Crk pY221 phosphorylation and signaling in cancer cell lines. Using nuclear magnetic resonance spectroscopy, we show that CypA binds to the Crk GPY motif via the catalytic PPII domain of CypA, and small-molecule nonimmunosuppressive inhibitors of CypA (Debio-025) disrupt the CypA-CrkII interaction and restores phosphorylation of Crk Y221. In cultured cell lines, Debio-025 suppresses cell migration, and when administered in vivo in an orthotopic model of triple-negative breast cancer, Debio-025 showed antitumor efficacy either alone or in combination with anti-PD-1 mAb, reducing both tumor volume and metastatic lung dispersion. Furthermore, when analyzed by NanoString immune profiling, treatment of Debio-025 with anti-PD-1 mAb increased both T-cell signaling and innate immune signaling in tumor microenvironment. IMPLICATIONS: These data suggest that pharmacologic inhibition of CypA may provide a promising and unanticipated consequence in cancer biology, in part by targeting the CypA/CrkII axis that regulates cell migration, tumor metastasis, and host antitumor immune evasion.

Oncogenic heterogeneous nuclear ribonucleoprotein D-like modulates the growth and imatinib response of human chronic myeloid leukemia CD34+ cells via pre-B-cell leukemia homeobox 1

Chronic myeloid leukemia (CML) originates from normal hematopoietic stem cells acquiring BCR-ABL fusion gene, specific BCR-ABL inhibitors (e.g., imatinib mesylate, IM) have greatly improved patient management. However, some patients are still suffering from relapse and drug resistance, which urges better understanding of the growth/survival mechanisms of CML stem/progenitor cells. In the present study, the role and its underlying mechanism of heterogeneous nuclear ribonucleoprotein D-like (HNRPDL) in CML cells were investigated. Firstly, overexpression of HNRPDL promoted the growth of murine BaF3 cells in vitro and induced leukemia in vivo, which was enhanced by co-expression of BCR-ABL. Conversely, HNRPDL silencing inhibited colony-forming cell (CFC) production of CML CD34⁺ cells and attenuated BCR-ABL induced leukemia. In addition, HNRPDL modulated imatinib response of K562 cells and HNRPDL silencing sensitized CML CD34⁺ cells to imatinib treatment. Mechanistically, we found the stability of pre-B-cell leukemia homeobox 1 (PBX1) mRNA was sustained by HNRPDL through its binding to a specific motif (ACUAGC) in 3'-untranslated region (3'-UTR) of PBX1. The expression of PBX1 was significantly higher in CML CD34⁺ cells than that in control cells and PBX silencing inhibited the growth of CML cells and sensitized them to imatinib treatment. In contrast, overexpression of PBX1 elevated the CFC production of normal hematopoietic CD34⁺ cells and "rescued" HNRPDL silencing induced growth inhibition and imatinib sensitization. Taken together, our data have demonstrated that HNRPDL transforms hematopoietic cells and a novel HNRPDL/PBX1 axis plays an important role in human CML CD34⁺ cells.

Selected reaction monitoring approach for validating peptide biomarkers

We here describe a selected reaction monitoring (SRM)-based approach for the discovery and validation of peptide biomarkers for cancer. The first stage of this approach is the direct identification of candidate peptides through comparison of proteolytic peptides derived from the plasma of cancer patients or healthy individuals. Several hundred candidate peptides were identified through this method, providing challenges for choosing and validating the small number of peptides that might prove diagnostically useful. To accomplish this validation, we used 2D chromatography coupled with SRM of candidate peptides. We applied this approach, called sequential analysis of fractionated eluates by SRM (SAFE-SRM), to plasma from cancer patients and discovered two peptides encoded by the peptidyl-prolyl cis-trans isomerase A (PPIA) gene whose abundance was increased in the plasma of ovarian cancer patients. At optimal thresholds, elevated levels of at least one of these two peptides was detected in 43 (68.3%) of 63 women with ovarian cancer but in none of 50 healthy controls. In addition to providing a potential biomarker for ovarian cancer, this approach is generally applicable to the discovery of peptides characteristic of various disease states.

Cyclophilin A promotes non-small cell lung cancer metastasis via p38 MAPK

BACKGROUND

Cyclophilin A (CypA) is associated with metastasis in diverse cancers; however, its role in lung cancer metastasis and the underlying mechanisms remain poorly understood. Our study investigated the effect of CypA on non-small cell lung cancer (NSCLC) metastasis in vitro and in vivo to determine its mechanisms.

METHODS

In this study, A549 and H1299 cell lines with downregulated and overexpressed CypA, respectively, were constructed by lentivirus transfection of NSCLC cells. in vitro experiments, including wound healing and transwell assays and Western blotting, showed that CypA promoted cancer cell migration and epithelial-mesenchymal transition in NSCLC. Lung metastasis mouse models were used for the first time to confirm that CypA promoted NSCLC metastasis in vivo. The p38 inhibitor SB203580 was used to show that p38 MAPK is involved in CypA-mediated NSCLC metastasis.

RESULTS

Wound healing and transwell assays showed that the migration of both A549 and H1299 cells decreased in the CypA downregulated group and increased in the CypA overexpressed group. CypA also positively promoted the expression of epithelial-mesenchymal transition-relevant proteins. Results of mouse models confirmed that the tumor metastasis rate was much higher in the CypA overexpressed than in the CypA downregulated group. In addition, SB203580 inhibited NSCLC cell migration significantly in the CypA overexpressed group, while the difference in the CypA downregulated group was not significant.

CONCLUSIONS

In conclusion, this study demonstrated that CypA promotes NSCLC cancer metastasis via p38 MAPK.

Cyclophilin A expression and its prognostic significance in lung adenocarcinoma

Cyclophilin A (CypA) has been reported to be upregulated in malignant tumors. CypA expression is thought to be associated with acquisition of tumor growth and anti-apoptotic function. Although upregulation of CypA has been reported in lung adenocarcinoma, its clinicopathological significance and roles in malignant progression remain unclear. Here we investigated the implications of CypA expression for outcome in patients with lung adenocarcinoma. Lung adenocarcinoma specimens from 198 cases were selected and reclassified according to the World Health Organization classification (4th edition) and the Noguchi classification. CypA expression was assessed by immunohistochemistry, and the H-score was calculated on the basis of intensity and proportion. The specificity of the antibody used was confirmed by Western blotting and the cut-off point was determined from the ROC curve. Sixty-seven cases (33.8%) had low CypA expression (CypA-L group) and 131 (66.2%) had high CypA expression (CypA-H group). Many cases of adenocarcinoma in situ were CypA-L, and advanced adenocarcinomas tended to be classified as CypA-H. Clinically, patients with CypA-H tumors showed a significantly poorer prognosis than those with CypA-L tumors. This is the first investigation of the implications of the CypA expression level in terms of the clinical characteristics of resected lung adenocarcinomas.

Deep-proteome mapping of WM-266-4 human metastatic melanoma cells: From oncogenic addiction to druggable targets

Cutaneous melanoma is a malignant tumor of skin melanocytes that are pigment-producing cells located in the basal layer (stratum basale) of epidermis. Accumulation of genetic mutations within their oncogenes or tumor-suppressor genes compels melanocytes to aberrant proliferation and spread to distant organs of the body, thereby resulting in severe and/or lethal malignancy. Metastatic melanoma's heavy mutational load, molecular heterogeneity and resistance to therapy necessitate the development of novel biomarkers and drug-based protocols that target key proteins involved in perpetuation of the disease. To this direction, we have herein employed a nano liquid chromatography-tandem mass spectrometry (nLC-MS/MS) proteomics technology to profile the deep-proteome landscape of WM-266-4 human metastatic melanoma cells. Our advanced melanoma-specific catalogue proved to contain 6,681 unique proteins, which likely constitute the hitherto largest single cell-line-derived proteomic collection of the disease. Through engagement of UNIPROT, DAVID, KEGG, PANTHER, INTACT, CYTOSCAPE, dbEMT and GAD bioinformatics resources, WM-266-4 melanoma proteins were categorized according to their sub-cellular compartmentalization, function and tumorigenicity, and successfully reassembled in molecular networks and interactomes. The obtained data dictate the presence of plastically inter-converted sub-populations of non-cancer and cancer stem cells, and also indicate the oncoproteomic resemblance of melanoma to glioma and lung cancer. Intriguingly, WM-266-4 cells seem to be subjected to both epithelial-to-mesenchymal (EMT) and mesenchymal-to-epithelial (MET) programs, with 1433G and ADT3 proteins being identified in the EMT/MET molecular interface. Oncogenic addiction of WM-266-4 cells to autocrine/paracrine signaling of IL17-, DLL3-, FGF(2/13)- and OSTP-dependent sub-routines suggests their critical contribution to the metastatic melanoma chemotherapeutic refractoriness. Interestingly, the 1433G family member that is shared between the BRAF- and EMT/MET-specific interactomes likely emerges as a novel and promising druggable target for the malignancy. Derailed proliferation and metastatic capacity of WM-266-4 cells could also derive from their metabolic addiction to pathways associated with glutamate/ammonia, propanoate and sulfur homeostasis, whose successful targeting may prove beneficial for advanced melanoma-affected patients.

Proline isomerisation as a novel regulatory mechanism for p38MAPK activation and functions

The stress-induced p38 mitogen-activated protein kinase (MAPK) pathway plays an essential role in multiple physiological processes, including cancer. In turn, p38MAPK phosphorylation at Thr180 and Tyr182 is a key regulatory mechanism for its activation and functions. Here we show that this mechanism is actively regulated through isomerisation of Pro224. Different cyclophilins can isomerise this proline residue and modulate the ability of upstream kinases to phosphorylate Thr180 and Tyr182. In vivo mutation of Pro224 to Ile in endogenous p38MAPK significantly reduced its phosphorylation and activity. This resulted in attenuation of p38MAPK signalling, which in turn caused an enhanced apoptosis and sensitivity to a DNA-damaging drug, cisplatin. We further found a reduction in size and number of lesions in homozygous mice carrying the p38MAPK P224I substitution in a K-ras model of lung tumorigenesis. We propose that cyclophilin-dependent isomerisation of p38MAPK is an important novel mechanism in regulating p38MAPK phosphorylation and functions. Thus, inhibition of this process, including with drugs that are in clinical trials, may improve the efficacy of current anti-cancer therapeutic regimes.

Protein disulfide isomerases: Impact of thapsigargin treatment on their expression in melanoma cell lines

Anti-cancer treatments usually elevate the content of unfolded or misfolded proteins in the endoplasmic reticulum (ER). Here we aimed to get insights into the relation between sensitivity of melanoma cell lines to the ER stress inducer thapsigargin (THG) and the genetic expression of protein disulfide isomerase family members (PDIs). The expression of PDIs was analysed by flow cytometry and real-time PCR. The results showed that SK-MEL-30, the less THG sensitive cell line, displays higher basal PDIs' expression levels and the sensitivity is increased by the PDIs inhibitor bacitracin. While SK-MEL-30 PDIs' expression is not THG dose-dependent, an increase in glucose related protein 78 (GRP78), PDIA5, PDIA6, and thioredoxin-related-transmembrane proteins' (TMX3 and TMX4) expression, in response to higher drug concentrations, was observed in MNT-1. The differences in PDIs' gene expression in MNT-1 suggest a different response to ER stress compared to the other cell lines and highlight the importance of understanding the diversity among cancer cells.

Comparative proteomic analysis reveals unique tumor protein composition among the melanoma subtypes pure desmoplastic and superficial spreading

The U.S. death rate for melanoma has not decreased, despite the use of depth at biopsy and sentinel lymph node status to determine the risk of metastasis. Additional prognostic indicators and therapeutic targets are required, and identification of candidate proteins was the goal of this study. We utilized comparative mass spectrometry to compare five samples of each of two forms of melanoma, pure desmoplastic, which by depth at diagnosis has a favorable prognosis, and superficial spreading. Ontological analysis was applied to identify proteins and networks that were increased in one of the two subtypes. Analysis revealed a protein signature increase in pure desmoplastic melanoma associated with cell-to-cell binding and a signature increase in superficial spreading melanoma responsible for the cellular stress response including a constellation of heat shock proteins. The two subtypes of melanoma compared in this study have two unique protein compositions that correlate with their phenotypes. Further validation studies are warranted to evaluate the utility of identified proteins as prognostic markers and therapeutic targets.

Expression and prognostic relevance of cyclophilin A and matrix metalloproteinase 9 in esophageal squamous cell carcinoma

Aims

To guide clinicians in selecting treatment options for esophageal squamous cell carcinoma (ESCC) patients, reliable markers predictive of clinical outcome are desirable. This study analyzed the correlation of cyclophilin A (CypA) and matrix metalloproteinase 9 (MMP9) in ESCC and their relationships to clinicopathological features and survival.

Methods

We immunohistochemically investigated 70 specimens of ESCC tissues using CypA and MMP9 antibodies. Then, the correlations between CypA and MMP9 expression and clinicopathological features and its prognostic relevance were determined.

Results

Significant correlations were only found in high level of CypA and MMP9 expression with tumor differentiation and lymph node status. Significant positive correlations were found between the expression status of CypA and that of MMP9. Overexpression of CypA and metastasis were significantly associated with shorter progression free survival times in univariate analysis. Multivariate analysis confirmed that CypA expression was an independent prognostic factor.

Conclusions

CypA might be correlated with the differentiation, and its elevated expression may be an adverse prognostic indicator for the patients of ESCC. CypA/MMP9 signal pathway may be attributed to the malignant transformation of ESCC, and attention should be paid to a possible target for therapy.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1166551968105508.

Cyclophilin A as a New Therapeutic Target for Hepatitis C Virus-induced Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) related to hepatitis B virus (HBV) and hepatitis C virus (HCV) infections is thought to account for more than 80% of primary liver cancers. Both HBV and HCV can establish chronic liver inflammatory infections, altering hepatocyte and liver physiology with potential liver disease progression and HCC development. Cyclophilin A (CypA) has been identified as an essential host factor for the HCV replication by physically interacting with the HCV non structural protein NS5A that in turn interacts with RNA-dependent RNA polymerase NS5B. CypA, a cytosolic binding protein of the immunosuppressive drug cyclosporine A, is overexpressed in many cancer types and often associated with malignant transformation. Therefore, CypA can be a good target for molecular cancer therapy. Because of antiviral activity, the CypA inhibitors have been tested for the treatment of chronic hepatitis C. Nonimmunosuppressive Cyp inhibitors such as NIM811, SCY-635, and Alisporivir have attracted more interests for appropriating CypA for antiviral chemotherapeutic target on HCV infection. This review describes CypA inhibitors as a potential HCC treatment tool that is contrived by their obstructing chronic HCV infection and summarizes roles of CypA in cancer development.

Identification of additional proteins in differential proteomics using protein interaction networks

In this study, we developed a novel computational approach based on protein-protein interaction networks to identify a list of proteins that might have remained undetected in differential proteomic profiling experiments. We tested our computational approach on two sets of human smooth muscle cell protein extracts that were affected differently by DNase I treatment. Differential proteomic analysis by saturation DIGE resulted in the identification of 41 human proteins. The application of our approach to these 41 input proteins consisted of four steps: (i) Compilation of a human protein-protein interaction network from public databases; (ii) calculation of interaction scores based on functional similarity; (iii) determination of a set of candidate proteins that are needed to efficiently and confidently connect the 41 input proteins; and (iv) ranking of the resulting 25 candidate proteins. Two of the three highest-ranked proteins, beta-arrestin 1, and beta-arrestin 2, were experimentally tested, revealing that their abundance levels in human smooth muscle cell samples were indeed affected by DNase I treatment. These proteins had not been detected during the experimental proteomic analysis. Our study suggests that our computational approach may represent a simple, universal, and cost-effective means to identify additional proteins that remain elusive for current 2D gel-based proteomic profiling techniques.

Downregulation of cyclophilin A by siRNA diminishes non-small cell lung cancer cell growth and metastasis via the regulation of matrix metallopeptidase 9

Background

Cyclophilin A (CypA) is a cytosolic protein possessing peptidyl-prolyl isomerase activity that was recently reported to be overexpressed in several cancers. Here, we explored the biology and molecular mechanism of CypA in non-small cell lung cancer (NSCLC).

Methods

The expression of CypA in human NSCLC cell lines was detected by real-time reverse transcription PCR. The RNA interference-mediated knockdown of CypA was established in two NSCLC cell lines (95C and A549). 239836 CypA inhibitor was also used to suppress CypA activity. Tumorigenesis was assessed based on cellular proliferation, colony formation assays, and anchorage-independent growth assays; metastasis was assessed based on wound healing and transwell assays.

Results

Suppression of CypA expression inhibited the cell growth and colony formation of A549 and 95C cells. CypA knockdown resulted in the inhibition of cell motility and invasion. Significantly, we show for the first time that CypA increased NSCLC cell invasion by regulating the activity of secreted matrix metallopeptidase 9 (MMP9). Likewise, suppression of CypA with 239836 CypA inhibitor decreased cell proliferation and MMP9 activity.

Conclusions

The suppression of CypA expression was correlated with decreased NSCLC cell tumorigenesis and metastasis.

Proteomic analysis in clear cell renal cell carcinoma: identification of differentially expressed protein by 2-D DIGE

Renal cell carcinoma (RCC), the most common neoplasm affecting the adult kidney, is characterised by heterogeneity of histological subtypes, drug resistance, and absence of molecular markers. Two-dimensional difference gel electrophoresis (2-D DIGE) technology in combination with mass spectrometry (MS) was applied to detect differentially expressed proteins in 20 pairs of RCC tissues and matched adjacent normal kidney cortex (ANK), in order to search for RCC markers. After gel analysis by DeCyder 6.5 and EDA software, differentially expressed protein spots were excised from Deep Purple stained preparative 2DE gel. A total of 100 proteins were identified by MS out of 2500 spots, 23 and 77 of these were, respectively, over- and down-expressed in RCC. The Principal Component Analysis applied to gels and protein spots exactly separated the two sample classes in two groups: RCC and ANK. Moreover, some spots, including ANXA2, PPIA, FABP7 and LEG1, resulted highly differential. The DIGE data were also confirmed by immunoblotting analysis for these proteins. In conclusion, we suggest that applying 2-D DIGE to RCC may provide the basis for a better molecular characterization and for the discovery of candidate biomarkers.

An Overview of Cyclophilins in Human Cancers

Cyclophilins (Cyps) belong to a group of proteins that have peptidyl-prolyl cis–trans isomerase (PPIase) and molecular chaperone activities. Originally, Cyps were identified as the intracellular receptors for the immunosuppressive drug cyclosporin A. Cyps are found in all prokaryotes and eukaryotes, and have been structurally conserved throughout evolution, implying their importance in cellular function. There are seven major Cyp isoforms in humans. CypA is up-regulated in many human cancers, and there is a strong correlation between over-expression of the CYPA gene and malignant transformation in some cancers. Moreover, CypA is directly under the transcriptional control of two critical transcription factors for cancer development: p53 and hypoxia inducible factor-1α. This review discusses the general biological functions of Cyps under a variety of stress conditions, and the importance and diverse roles of over-expression of CYP genes in human cancers, with a particular emphasis on CYPA. These oncogenic properties suggest that CypA is a promising target for cancer therapy.

Proteomic approach reveals novel targets for retinoic acid-mediated therapy of thyroid carcinoma

Our previous studies demonstrated that retinoic acid (RA)-induced reduction of both, the key glycolytic enzyme ENO1 and proliferation-promoting c-Myc, resulted in decreased vitality and invasiveness of the follicular thyroid carcinoma cell lines FTC-133 and FTC-238. By employing two-dimensional electrophoresis and mass spectrometry, we identified proteins affected by RA treatment. In addition to previously reported decrease in ENO1 expression, we found that RA led to significantly reduced levels of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), pyruvate kinase isoenzymes M1/M2 (PKM1/M2), peptidyl-prolyl cis-trans isomerase A (PPIA), transketolase (TKT), annexin A2 (ANXA2), glutathione S-transferase P (GSTP1) and peroxiredoxin 2 (PRDX2) as compared to untreated control. The same proteins investigated on thyroid tissues were found to be significantly up-regulated in follicular, papillary and undifferentiated thyroid carcinomas when compared with goiter and adenoma tissues. These findings identify new target proteins for RA-mediated anti-tumor and re-differentiation therapies and provide novel insights into treatments for thyroid carcinoma.

A novel function for vimentin: the potential biomarker for predicting melanoma hematogenous metastasis

Background

The incidence of malignant melanoma (MM) was occurring at a faster rate than for most neoplasm worldwide, and melanoma metastasis is still the most formidable problem. So it is necessarily to find some biomarkers associated with melanoma metastasis.

Methods

In our study, 8 spontaneous lung metastatic mice models were created by B16F10 subcutaneously transplantation. The differential protein profiles of two kinds of subcutaneous transplanted tumor tissues, which was parental B16F10 (B16 group) and corresponding lung metastases (B16M group) were detected by two-dimensional differential in-gel electrophoresis (2D-DIGE) combined with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS). Western blotting was used to validate the results, and the clinical significance of individual protein was detected furtherly in a set of human samples.

Result

In this study, thirty proteins were found to be differentially expressed (ratio > 2 or < -2, P < 0.01) and thirteen of them were identified by MS. Highly expressed proteins in B16M group included cytoskeleton/structure proteins (vimentin, gamma-actin, β-actin, laminin binding protein), the chaperone family of proteins (heavy-chain binding protein, Bip), immunoproteasome assembly (proteasome activator REG alpha) and others involved in glycolysis activity (PGK1, enolase, TPI, human skeletal muscle GAPDH) and protein transport (myoglobin). Vimentin was significantly up-regulated in B16M group compared with B16 group which was validated by western blotting. Immunohistochemistry was performed in a set of clinical samples, the results showed that over-expression of vimentin was frequently observed in primary melanoma patients with hematogenous metastasis (P < 0.05), not associated with lymph node metastasis (P > 0.05). The presence of TNM stage was a independent indicator of poor prognosis for melanoma patients (P = 0.004).

Conclusion

The aberrant immunohistochemical expression of vimentin in primary melanoma tissues may help to call attention for patients with high risk of hematogenous metastasis. That might be as a novel metastatic indicator for melanoma. In a word, vimentin is not only the dignostic marker but also the hematogenous metastasis predictor for melanomas clinically.

Role of cyclophilin a during oncogenesis

Cyclophilins (Cyps) are ubiquitously expressed proteins that are evolutionarily conserved. CypA is the most abundant among the Cyps and is expressed in the cytosol. With its chaperone and PPIase activities, CypA contributes to the maintenance of correct conformation of nascent or denatured proteins and also provides protection against environmental insults. Also, its expression is induced in response to a wide variety of stressors including cancer. Upregulation of CypA in small cell lung cancer, pancreatic cancer, breast cancer, colorectal cancer, squamous cell carcinoma and melanoma has been reported. In some cancers a correlation between CypA overexpression and malignant transformation has been established. While molecular partners of CypA that promote cancer development are yet to be discovered, various mechanisms have been proposed to account for the cytoprotective functions of CypA during cancer development. CypA may promote the survival of cells under the stressful condition of cancer. CypA may well be essential for maintaining the conformation of oncogenic proteins, signalling proteins for cell proliferation, antiapoptotic components, transcription factors, or cell motility regulatory proteins. Antioxidant effects of CypA, which have been suggested by some researchers, may also become critical to reactive oxygen species (ROS) creating an oncogenetic environment. Developing new CypA inhibitors for therapeutics has been surmised from the cytoprotective functions of CypA and its overexpression in many cancer types. Therefore, CypA can be further investigated as a useful tool for early diagnosis, treatment and prevention of human cancers.

Identification of tyrosine-phosphorylated proteins associated with metastasis and functional analysis of FER in human hepatocellular carcinoma cells

BACKGROUND

Aberrant activity of tyrosine-phosphorylated proteins is commonly associated with HCC metastasis. Cell signaling events driven by these proteins are implicated in numerous processes that alter cancer cell behavior. Exploring the activities and signaling pathways of these proteins in HCC metastasis may help in identifying new candidate molecules for HCC-targeted therapy.

METHODS

Hep3B (a nonmetastatic HCC cell line) and MHCC97H (a highly metastatic HCC cell line) were used in this study, and the tyrosine-phosphorylated proteins expressed in these cell lines were profiled by a phosphoproteomics technique based on LC-MS/MS. Protein-protein interaction and functional clustering analyses were performed to determine the activities of the identified proteins and the signaling pathways closely related to HCC metastasis.

RESULTS

In both cell lines, a total of 247 phosphotyrosine (pTyr) proteins containing 281 pTyr sites were identified without any stimulation. The involvement of almost 30% of these in liver or liver cancer has not been reported previously. Biological process clustering analysis indicated that pTyr proteins involved in cell motility, migration, protein autophosphorylation, cell-cell communication, and antiapoptosis functions were overexpressed during metastasis. Pathway clustering analysis revealed that signaling pathways such as those involved in EGFR signaling, cytokine- and chemokine-mediated signal transduction, and the PI3K and JAK-STAT cascades were significantly activated during HCC metastasis. Moreover, noncanonical regulation of the JNK cascade might also provide new targets for HCC metastasis. After comparing the pTyr proteins that were differentially expressed during HCC cell metastasis, we selected FER, a nonreceptor tyrosine kinase, and validated its role in terms of both expression and function. The data confirmed that FER might play a critical role in the invasion and metastasis of HCC.

CONCLUSION

The identification of pTyr proteins and signaling pathways associated with HCC metastasis could provide useful information for selecting new molecular intervention targets. Moreover, FER might serve as a novel drug target in future HCC therapy.