Proteomic profiling of differential display analysis for human oral squamous cell carcinoma: 14-3-3 σ Protein is upregulated in human oral squamous cell carcinoma and dependent on the differentiation level

Oral squamous cell carcinoma (OSCC) has an absolute majority of all oral cancer. We used proteomic technology to analyze the protein expression profile in OSCC tissues and accompanying surrounding normal tissues in four oral locations (buccal mucosa, gingival mucosa, oral floor, and tongue). Ten protein spots were overexpressed more strongly in cancer tissues than normal ones, and were identified as proliferating cell nuclear antigen, 14-3-3 ε, 14-3-3 σ, proteasome subunit α type 5, translationally controlled tumor protein, eukaryotic translation initiation factor 3 subunit, macrophage capping protein, and mitochondrial isocitrate dehydrogenase subunit α. Macrophage capping protein and mitochondrial isocitrate dehydrogenase subunit α had two spots. Especially, we focused on 14-3-3 σ protein, one of the eight identified proteins, and assessed its expression level in four oral locations of OSCC by using differential display methods. The expression level of 14-3-3 σ protein was upregulated in four locations of oral cavity. Eight proteins which we identified in this study may play an important role in OSCC carcinogenesis and progression and could be used as diagnostic biomarkers of OSCC.     

Decreased annexin A3 expression correlates with tumor progression in papillary thyroid cancer

Purpose : The aim of this study is to identify the potential tumor markers that function in carcinogenesis and tumor progression, thus providing important diagnostic and prognostic information. Experimental design : We performed 2‐D gel electrophoresis and MALDI‐TOF MS to investigate the differentially expressed proteins in 25 papillary thyroid carcinoma tissues. For validation of candidate proteins and investigation of clinical significance, we performed Western, Northern blot analysis and immunohistochemical staining. Results : Our proteomic analyses revealed significantly decreased annexin A3 expression in papillary thyroid carcinoma at both the protein and mRNA levels, compared with normal thyroid tissue. ANXA3 immunoreactivity was not significantly correlated with lymph node metastasis, multifocality, capsular invasion or perithyroidal extension in thyroid cancer. However, the tumor subgroup with a lymph node metastasis score of >3 displayed significantly lower ANXA3 expression than did subgroups with negative and ≤3 scores (p=0.001). Moreover, ANXA3 expression was markedly lower in large tumors (>1 cm in diameter) than in microcarcinomas (p=0.001). Conclusion and clinical relevance : Decreased expression of ANXA3 in papillary thyroid cancer supports the idea that ANXA3 may be an effective marker of microcarcinoma, and a negative predictor of papillary thyroid cancer progression.     

Protein profiling of oral brush biopsies: S100A8 and S100A9 can differentiate between normal, premalignant, and tumor cells

In oral mucosa lesions it is frequently difficult to differentiate between precursor lesions and already manifest oral squamous cell carcinoma. Therefore, multiple scalpel biopsies are necessary to detect tumor cells already in early stages and to guarantee an accurate follow‐up. We analyzed oral brush biopsies (n = 49) of normal mucosa, inflammatory and hyperproliferative lesions, and oral squamous cell carcinoma with ProteinChip Arrays (SELDI) as a non‐invasive method to characterize putative tumor cells. Three proteins were found that differentiated between these three stages. These three proteins are able to distinguish between normal cells and tumor cells with a sensitivity of 100% and specificity of 91% and can distinguish inflammatory/hyperproliferative lesions from tumor cells with a sensitivity of up to 91% and specificity of up to 90%. Two of these proteins have been identified by immunodepletion as S100A8 and S100A9 and this identification was confirmed by immunocytochemistry. For the first time, brush biopsies have been successfully used for proteomic biomarker discovery. The identified protein markers are highly specific for the distinction of the three analyzed stages and therewith reflect the progression from normal to premalignant non‐dysplastic and finally to tumor tissue. This knowledge could be used as a first diagnostic step in the monitoring of mucosal lesions.     

Diagnostic protein marker patterns in squamous cervical cancer

Purpose: Cervical cancer is the second most prevalent malignancy of women. Our aim was to identify additional marker protein patterns for objective diagnosis of squamous cervical cancer (SCC). Experimental design: Collected tissue biopsies of SCC, squamous vaginal cancer (SVC), normal cervical and vaginal mucosa were subjected to 2‐DE, SameSpot analysis, MALDI‐TOF‐MS protein identification, and analysis of the expression of selected proteins by immunohistochemistry. Results: In 148 protein spots selected by the difference in expression 99 proteins were identified. A differential protein pattern for SCC was, e.g. over‐expressed (OE) eukaryotic translation initiation factor 3‐2β, neutrophil cytosolic factor 2, annexin A6 (ANXA6), for SVC it was OE cathepsin D, γ‐catenin, RAB2A, for both cancers it was OE apolipoprotein E, tropomyosin 3, HSPA8, and underexpressed cytokeratin 13, osteoglycin. In SCC nuclear expression of neutrophil cytosolic factor 2, PRDX2, HSP27 (nine of ten cases), ANXA6 (nine of ten cases) was observed while tropomyosin 4 was expressed only in two of ten cases. There was 81.1% (43/53) agreement between the expression of protein spots and the immune expression of proteins ( www.proteinatlas.org ). Conclusions and clinical relevance: SCC is characterized by specific tissue marker protein patterns that allow objective detection of the disease. They can become a basis for objective automated cytology‐based screening and improve current diagnostics of SCC.     

Characterisation of tumoral markers correlated with ErbB2 (HER2/Neu) overexpression and metastasis in breast cancer

The receptor tyrosine kinase ErbB2 (HER2/neu) is overexpressed in ?30% of breast cancers and is associated with poor prognosis and an increased likelihood of metastasis. Clinical treatments such as trastuzumab are effective in less than 35% of women diagnosed as ErbB2‐positive, highlighting the necessity of searching for novel targets and alternative therapies. Herein, a proteomic screening strategy combining quantitative‐based gel electrophoresis and MS was used to compare the protein expression of 48 normal human breast and tumour tissues differing in ErbB2 expression and lymph node status. The aim was to identify proteins associated with the aggressive phenotype of ErbB2‐positive breast cancer which could be potential biomarkers of the disease as well as therapy targets. In total, 177 protein isoforms (107 gene products) differentially expressed between tissue groups were identified. Immunohistochemical staining of a tissue‐microarray was used for validation of selected protein candidates. We found that expression of HSP90α, laminin and GSTP1 significantly correlated with ErbB2 expression, while others such as AGR2, NM23H1 and Annexin 2 were overexpressed in greater than 40% of tumours. Finally, knocking‐down the expression by RNA interference of three candidates, AGR2, Transgelin2 and NM23H1 resulted in an enhanced invasive capacity of MDA‐MB435 cells. These data support the involvement of these targets in tumour progression and identify them as novel biomarkers of the disease.     

Quantitative proteomic analysis of a paired human liver healthy versus carcinoma cell lines with the same genetic background to identify potential hepatocellular carcinoma markers

To comprehensively measure global changes in protein expression associated with human hepatocellular carcinoma (HCC), comparative proteomic analysis of two cell lines derived from the healthy and carcinoma tissue of a same donor respectively was conducted using quantitative amino acid-coded mass tagging /stable isotope labeling with amino acids in cell culture-based LC-MS/MS approach. Among a total of 501 proteins precisely quantified, the expressions of 128 proteins were significantly altered including 70 proteins up-regulated and 58 down-regulated in HCC cells. According to their previously characterized functions, the differentially expressed proteins were found associated with nine functional categories including glycolysis, stress response, cell communication, cell cycle, apoptosis/death, etc. For example, multiple enzymes involving glycolysis pathway were found differentially regulated in HCC cells, illustrating the critical participation of glycolysis in the HCC transformation. The accuracy of certain differentially expressed proteins identified through the amino acid-coded mass tagging-based quantification was validated in the paired cell lines, and later their pathological correlations were examined in multiple clinical pairs of normal versus tumor tissues from HCC specimen by using a variety of biological approaches including Western blotting and in situ immunoassays. These consistencies suggested that multiple proteins such as HSP27, annexin V, glyceraldehyde-3-phosphate dehydrogenase, nucleolin and elongation factor Tu could be the biomarkers candidates for diagnosis of HCC.     

Expression of tropomyosin alpha 4 chain is increased in esophageal squamous cell carcinoma as evidenced by proteomic profiling by two-dimensional electrophoresis and liquid chromatography-mass spectrometry/mass spectrometry

To identify proteins associated with esophageal carcinogenesis, we performed protein profiling of 16 esophageal squamous cell carcinomas (ESCCs) and paired noncancerous tissues by 2-DE and MS/MS. In cancerous tissues, three spots showed significant up-regulation in the amount of protein, while eight spots were significantly down-regulated. The identities of the spots were determined by PMF with LC-MS/MS and were confirmed by immunoblotting. The up-regulated proteins were tropomyosin alpha 4 chain, transgelin, and pyruvate kinase. The down-regulated proteins were serum albumin precursor, isoforms of annexin A1, tropomyosin beta chain, 14-3-3 protein sigma, and isoforms of serotransferrin precursor. In all 16 cases, up-regulation of the tropomyosin alpha 4 chain was confirmed by immunoblotting. Localization of the tropomyosin alpha 4 chain in ESCC cells and adjacent fibroblasts was confirmed by immunohistochemistry.     

Discovery of putative oocyte quality markers by comparative ExacTag proteomics

Purpose: Identification of the biomarkers of oocyte quality, and developmental and reprogramming potential is of importance to assisted reproductive technology in humans and animals. Experimental design: PerkinElmer ExacTag? Kit was used to label differentially proteins in pig oocyte extracts (oocyte proteome) and pig oocyte‐conditioned in vitro maturation media (oocyte secretome) obtained with high‐ and low‐quality oocytes. Results: We identified 16 major proteins in the oocyte proteome that were expressed differentially in high‐ versus low‐quality oocytes. More abundant proteins in the high‐quality oocyte proteome included kelch‐like ECH‐associated protein 1 (an adaptor for ubiquitin‐ligase CUL3), nuclear export factor CRM1 and ataxia‐telangiectasia mutated protein kinase. Dystrophin (DMD) was more abundant in low‐quality oocytes. In the secretome, we identified 110 proteins, including DMD and cystic fibrosis transmembrane conductance regulator, two proteins implicated in muscular dystrophy and cystic fibrosis, respectively. Monoubiquitin was identified in the low‐quality‐oocyte secretome. Conclusions and clinical implications: A direct, quantitative proteomic analysis of small oocyte protein samples can identify potential markers of oocyte quality without the need for a large amount of total protein. This approach will be applied to discovery of non‐invasive biomarkers of oocyte quality in assisted human reproduction and in large animal embryo transfer programs.     

iTRAQ‐Based Quantitative Proteomic Analyses of High Grade Esophageal Squamous Intraepithelial Neoplasia

Esophageal squamous cell carcinoma (ESCC) is one of the most common cancers worldwide and is the fourth most lethal cancer in China. Little is known about the proteome of high grade esophageal squamous intraepithelial neoplasia (HGN), which is a premalignant lesion of ESCC. A quantitative proteomic analysis using an isobaric tag for relative and absolute quantification (iTRAQ) approach is used to characterize the protein expression profiles in HGN. Among the 3156 identified proteins, a total of 236 proteins are discovered to be differentially expressed. Compared with paired normal esophageal epithelial tissues, 138 proteins are upregulated and 98 proteins are downregulated in HGN. Bioinformatics analyses are performed according to gene ontology, clusters of orthologous groups, and kyoto encyclopedia of genes and genomes enrichment analyses. Six differentially expressed proteins are chosen and validated by Western blotting. The results of the study increase our understanding of early tumorigenesis during ESCC, and provide insights into the proteome at the initial stages of the disease that can be used to identify potential biomarkers for early diagnosis and for therapeutic targets.     

Proteomic profiling of cancer of the gingivo-buccal complex: Identification of new differentially expressed markers

Tobacco-related oral cancer is the most common cancer among Indian males, gingivo-buccal complex (GBC) being the most affected subsite due to the habit of chewing tobacco. Proteins from the lysates of microdissected normal and transformed epithelium from clinically well-characterized tissue samples of the GBC were separated by two-dimensional gel electrophoresis to identify differentially expressed proteins. Eleven protein spots showed differential expression, which could withstand the stringency of statistical evaluation. The observations were confirmed with additional tissues. Nine of these differentiators were identified by MS as lactate dehydrogenase B, α-enolase, prohibitin, cathepsin D, apolipoprotein A-I, tumor protein translationally controlled-1, an SFN family protein, 14-3-3σ and tropomyosin. Cluster analysis indicated that these proteins, as a coexpressed set, could distinguish normal and transformed epithelium. Functionally, these differentiator molecules are relevant to the pathways and processes that have been previously implicated in oral carcinogenesis and could therefore be investigated further as a panel of markers for management of cancer of the GBC.     

Protein-induced changes during the maturation process of human dendritic cells: A 2-D DIGE approach

Dendritic cells (DCs) are unique antigen presenting cells, which upon maturation change from a specialized antigen‐capturing cell towards a professional antigen presenting cells. In this study, a 2‐D DIGE analysis of immature and mature DCs was performed, to identify proteins changing in expression upon maturation. The protein expression profile of immature and mature DCs, derived from CD14⁺ peripheral blood monocytes was investigated using two pH ranges (pH 4–7 and 6–9) (n = 4). Ninety one differentially expressed spots (p<0.01) were detected, from which we identified 74 spots (81.32%) corresponding to 41 different proteins. The proteins identified play a role in diverse processes, such as antigen processing/presentation, vesicle transport and cytoskeleton remodeling. In addition, a protein interaction network contained 29 (out of 41) proteins, suggesting that, although they functionally originate from distinct classes, these proteins are acting as a protein‐interactome. In conclusion, the proteins shown here to be altered in expression upon maturation are in line with the morphological and functional changes observed during the maturation process, providing a better understanding of the processes involved. This will open new avenues for investigating treatment regimens for immune‐associated disorders.     

Differentially expressed proteins of MCF-7 human breast cancer cells affected by Zilongjin, a complementary Chinese herbal medicine

Purpose : Zilongjin, a complementary Chinese herbal medicine, has been used to alleviate the adverse effects of chemotherapeutic drugs in cancer therapy. However, the mechanisms of anti‐cancer activity of Zilongjin are still largely unkonwn. Experimental design : First, the proteomic approach of combined 2‐DE and ESI‐MS/MS was used to investigate the effect of Zilongjin on the protein expression in MCF‐7 cells. Then, the differential expression of some proteins was confirmed by Western blot, cytoimmunofluoresecnce, and quantitative real‐time RT‐PCR analysis. Results : The identified proteins with differential expression, involved in such events as protein translation, cellular signal transduction, cytoskeleton formation and transportation, include seven downregulating proteins, such as Eukaryotic translation initiation factor 3 subunit I, Eukaryotic translation initiation factor 1A Y‐chromosomal, Ran‐specific GTPase‐activating protein, Ubiquitin‐conjugating enzyme E2 N, Tropomodulin‐3, Macrophage‐capping protein, and Tumor protein D52, as well as two upregulating proteins, HSP β‐1 and keratin18. Moreover, the differential expression of three proteins was confirmed. Conclusions and clinical relevance : (i) These results provide a new insight into the molecular mechanisms of Zilongjin on therapy for breast cancer. (ii) The application of the proteomic approaches will result in the more extended appreciation of Chinese medicine than those known at present.     

Discovery of stage-related proteins in esophageal squamous cell carcinoma using proteomic analysis

Esophageal squamous cell carcinoma (ESCC) is the major subtype of esophageal cancers in China, and characterized with high morbidity and mortality. So far, the diagnosis of ESCC is mainly dependent on the alterations in esophageal histology, but most cases of ESCC with low stage do not display visible histological abnormalities. Therefore, a deep understanding of the mechanism of ESCC progression and seeking stage-specific molecules might improve the diagnosis and therapy for ESCC. In this study, we used proteomics to analyze ESCC tissues with classification by TNM stage, and determined the proteomic features correlated with ESCC progression (from stages I to III). Proteins that exhibited significantly different expression patterns between ESCC and corresponding normal esophageal tissues were identified using MS. The identified proteins with differentiated expression mainly fell into three protein categories (i.e. cytoskeleton system-associated proteins, metabolism enzymes, and heat shock proteins). In addition, real-time PCR highlighted some molecules that were associated with tumor stages at the mRNA level, such as enolase 1, chromosome 1 ORF 10, elastase inhibitor, α B crystalline, stress-induced phosphoprotein 1, and squamous cell carcinoma antigen 1. Altogether, these data provided further information on ESCC progression and potential drug targets for ESCC clinical therapy.     

Membrane Proteome of Invasive Retinoblastoma: Differential Proteins and Biomarkers

Purpose: Retinoblastoma (RB) is a pediatric ocular cancer which is caused due to the aberrations in the RB1 gene. The changes in the membrane proteomics would help in understanding the development of the retinoblastoma and could identify candidates for biomarkers and therapy. Experimental design: Quantitative proteomics is performed on the enriched membrane fractions from pooled normal retina (n = 5) and pooled retinoblastoma tissues (n = 5). The proteins are tryptic‐digested and tagged with iTRAQ labels. Orbitrap mass spectrometry is used to analyze and quantify the deregulated membrane proteins involved in the RB tumor progression. Immunohistochemistry (IHC) is used to further validate few of the differentially expressed proteins. Results: A total of 3122 proteins are identified of which, 663 proteins are found to be deregulated with ≥two fold change in the RB tumor compared to the retina. 282 proteins are upregulated and 381 are downregulated with ≥2 peptide identifications. Bioinformatic analysis revealed that, most of the proteins are involved in the transport, cellular communication, and growth. Overexpression of lamin B1 (LMNB1) and transferrin receptor (TFRC) are observed in RB tumors using IHC. Conclusion and clinical relevance: The present study, is the first comprehensive quantitative membrane proteomic atlas of the differentially regulated proteins in RB compared to the retina. LMNB1 and TFRC could be potential biomarkers for this childhood cancer.     

Proteomic profiling of 13 paired ductal infiltrating breast carcinomas and non-tumoral adjacent counterparts

According to recent statistics, breast cancer remains one of the leading causes of death among women in Western countries. Breast cancer is a complex and heterogeneous disease, presently classified into several subtypes according to their cellular origin. Among breast cancer histotypes, infiltrating ductal carcinoma represents the most common and potentially aggressive form. Despite the current progress achieved in early cancer detection and treatment, including the new generation of molecular therapies, there is still need for identification of multiparametric biomarkers capable of discriminating between cancer subtypes and predicting cancer progression for personalized therapies. One established step in this direction is the proteomic strategy, expected to provide enough information on breast cancer profiling. To this aim, in the present study we analyzed 13 breast cancer tissues and their matched non-tumoral tissues by 2-DE. Collectively, we identified 51 protein spots, corresponding to 34 differentially expressed proteins, which may represent promising candidate biomarkers for molecular-based diagnosis of breast cancer and for pattern discovery. The relevance of these proteins as factors contributing to breast carcinogenesis is discussed.     

An application of the 2-nitrobenzenesulfenyl method to proteomic profiling of human colorectal carcinoma: A novel approach for biomarker discovery

In the development of novel biomarkers, the proteomic approach is advantageous because using it the cancer-associated proteins can be directly identified. We previously developed a 2-nitrobenzenesulfenyl (NBS) method to improve quantitative proteome analysis. Here, we applied this method to proteomic profiling of colorectal carcinoma (CRC) to identify novel proteins with altered expression in CRC. Each pair of tumor and normal tissue specimens from 12 CRC patients was analyzed, and approximately 5000 NBS-labeled paired peaks were quantified. Peaks with altered signal intensities (>1.5-fold) and occurring frequently in the samples (>70%) were selected, and 128 proteins were identified by MS/MS analyses as differentially expressed proteins in CRC tissues. Many proteins were newly revealed to be CRC related; 30 were reported in earlier studies of CRC. Six proteins that were up-regulated in CRC (ZYX, RAN, RCN1, AHCY, LGALS1, and VIM) were further characterized and validated by Western blot and immunohistochemistry. All six were found to be CRC-localized, either in cancer cells or in stroma cells near the cancer cells. These results indicate that the proteins identified in this study are novel candidates for CRC markers, and that the NBS method is useful in proteome mining to discover novel biomarkers.     

Anatomic site‐specific proteomic signatures of gastrointestinal stromal tumors

The gastrointestinal stromal tumor (GIST) is the most common mesenchymal malignancy of the gastrointestinal tract. Its clinical course ranges widely from a curable disorder to a highly malignant disease. Although its clinical and molecular characteristics depend on the anatomic site of origin, the molecular background of GIST arising in different anatomical site has not been studied yet. To investigate the proteomic background of GIST, we examined the proteomic features corresponding to the anatomic site of tumor origin. Comparison of the proteomic profile of gastric (23 cases) and small intestinal (9 cases) GIST by 2‐DE revealed 105 protein spots with significantly different intensity (p <0.01) between the two groups. Mass spectrometric study identified 68 distinct proteins for these 105 protein spots, including cancer‐associated ones such as prohibitin, pigment epithelium‐derived factor, and alpha‐actinin 4. The intensity of 37/105 (35.2%) protein spots was significantly concordant with the corresponding mRNA levels (p <0.01). Although both 2‐D DIGE and microarray experiments showed significant up‐regulation of vimentin expression in small intestinal GIST, Western blotting did not show a significant difference between the two groups. In conclusion, our study demonstrates the proteins specially expressed in GIST depending on their site of origin, as well as the unique advantage offered by use of proteomics to acquire such data. The identified proteins may provide clues to understanding the different characteristics of GIST depending on their site of origin.     

Toward the Proteome of the Human Peripheral Blood Eosinophil

Eosinophils (EOSs) are granular leukocytes that have significant roles in many inflammatory and immunoregulatory responses, especially asthma and allergic diseases. We have undertaken a fairly comprehensive proteomic analysis of purified peripheral blood EOSs from normal human donors primarily employing 2‐DE with protein spot identification by MALDI‐MS. Protein subfractionation methods employed included IEF (Zoom^® Fractionator) and subcellular fractionation using differential protein solubilization. We have identified 3141 proteins, which had Mascot expectation scores of 10^?3 or less. Of these 426 were unique and non‐redundant of which 231 were novel proteins not previously reported to occur in EOSs. Ingenuity Pathway Analysis showed that some 70% of the non‐redundant proteins could be subdivided into categories that are clearly related to currently known EOS biological activities. Cytoskeletal and associated proteins predominated among the proteins identified. Extensive protein posttranslational modifications were evident, many of which have not been previously reported that reflected the dynamic character of the EOS. This data set of eosinophilic proteins will prove valuable in comparative studies of disease versus normal states and for studies of gender differences and polymorphic variation among individuals.     

Identification of distinctive protein expression patterns in colorectal adenoma

Purpose: As a pre‐malignant precursor, adenoma provides an ideal tissue for proteome profiling to investigate early colorectal cancer development and provide possible targets for preventive interventions. The aim of this study was to identify patterns of differential protein expression that distinguish colorectal adenoma from normal tissue. Experimental design: Twenty paired samples of adenoma and normal mucosa were analysed by 2‐DE and MALDI‐TOF/TOF MS to detect proteins with ≥2‐fold differential expression. Results: Four proteins were up‐regulated in adenoma (Annexin A3, S100A11, S100P and eIF5A‐1) and three were down‐regulated (Galectin‐1, S100A9 and FABPL). S100P, galectin‐1, S100A9 and FABPL expression was localised by immunohistochemistry. Conclusions and clinical relevance: Distinctive patterns of in vivo protein expression in colorectal adenoma were identified for the first time. These proteins have important functions in cell differentiation, proliferation and metabolism, and may play a crucial role in early colorectal carcinogenesis. The ability to recognise premalignant lesions may have important applications in cancer prevention.     

Identification of melanoma‐specific serological markers using proteomic analyses

The discovery of novel melanoma markers for not only early detection but also monitoring disease status is promising to improve the clinical outcome of patients. In the present study, we performed proteomic comparative analysis of plasma proteins between healthy volunteers and melanoma patients using NanoLC and MALDI‐TOF‐MS. As a result, we were successful in identifying nine proteins that were specifically expressed in melanoma plasma compared with healthy plasma, most of which had not previously been identified as plasma markers of melanoma. The mRNA expression levels of four proteins [pro‐platelet basic protein precursor (PPBP), serum amyloid A2 (SAA2), complement factor H‐related protein 1 precursor (FHR1), inter‐alpha‐trypsin inhibitor heavy chain H4 precursor (IAIH4)] were prominently up‐regulated in several melanoma cell lines compared with melanocytes. Moreover, two proteins (PPBP, SAA) were shown to be expressed in tumor specimens from melanoma patients. In the survival time analysis regarding melanoma patients, the semi‐quantified plasma PPBP levels were statistically negatively correlated with the survival time. Most interestingly, the significant survival benefit was seen in low PBPP level group (< index 20) versus high level (≥ index 20) group. The results suggest that PPBP might be a novel promising serological marker and a prognostic factor specific to melanomas.