Macrophage-capping protein as a tissue biomarker for prediction of response to gemcitabine treatment and prognosis in cholangiocarcinoma

CAPG is a novel biomarker for early gastric cancer and is involved in the Wnt/β-catenin signaling pathway

Past studies have shown that the Gelsolin-like actin-capping protein (CAPG) regulates cell migration and proliferation and is strongly associated with tumor progression. We present the first study of the mechanism of action of CAPG in early gastric cancer (EGC). We demonstrate that CAPG expression is upregulated in gastric cancer (GC) especially EGC. CAPG promotes GC proliferation, migration, invasion, and metastasis in vivo and in vitro. More importantly, CAPG plays a role in GC by involving the Wnt/β-catenin signaling pathway. Our findings suggest that CAPG may function as a novel biomarker for EGC.

The migration behavior of human glioblastoma cells is influenced by the redox-sensitive human macrophage capping protein CAPG

The macrophage capping protein CAPG belongs to the gelsolin superfamily which modulates actin dynamics by capping the growing end of actin filaments in a Ca²⁺- and PIP₂-dependent manner resulting in polymerization inhibition of actin filaments. In the last years, additional functions for CAPG in transcription regulation were described and higher CAPG amounts have been linked to increased invasiveness and migration behavior in different human tumor entities like e.g. glioblastoma. Nevertheless, there is a lack of knowledge how additional functions of CAPG are regulated. As CAPG contains several cysteine residues which may be accessible to oxidation we were especially interested to investigate how alterations in the cysteine oxidation state may influence the function, localization, and regulation of CAPG. In the present study, we provide strong evidence that CAPG is a redox-sensitive protein and identified two cysteines: C282 and C290 as reversibly oxidized in glioblastoma cell lines. Whereas no evidence could be found that the canonical actin capping function of CAPG is redox-regulated, our results point to a novel role of the identified cysteines in the regulation of cell migration. Along with this, we found a localization shift out of the nucleus of CAPG and RAVER1, a potential interaction partner identified in our study which might explain the observed altered cell migration properties. The newly identified redox sensitive cysteines of CAPG could perspectively be considered as new targets for controlling tumor invasive properties.

Mass spectrometry-based analysis of formalin-fixed, paraffin-embedded distal cholangiocarcinoma identifies stromal thrombospondin-2 as a potential prognostic marker

Background

Distal cholangiocarcinoma is an aggressive malignancy with a dismal prognosis. Diagnostic and prognostic biomarkers for distal cholangiocarcinoma are lacking. The aim of the present study was to identify differentially expressed proteins between distal cholangiocarcinoma and normal bile duct samples.

Methods

A workflow utilizing discovery mass spectrometry and verification by parallel reaction monitoring was used to analyze surgically resected formalin-fixed, paraffin-embedded samples from distal cholangiocarcinoma patients and normal bile duct samples. Bioinformatic analysis was used for functional annotation and pathway analysis. Immunohistochemistry was performed to validate the expression of thrombospondin-2 and investigate its association with survival.

Results

In the discovery study, a total of 3057 proteins were identified. Eighty-seven proteins were found to be differentially expressed (q < 0.05 and fold change ≥ 2 or ≤ 0.5); 31 proteins were upregulated and 56 were downregulated in the distal cholangiocarcinoma samples compared to controls. Bioinformatic analysis revealed an abundance of differentially expressed proteins associated with the tumor reactive stroma. Parallel reaction monitoring verified 28 proteins as upregulated and 18 as downregulated in distal cholangiocarcinoma samples compared to controls. Immunohistochemical validation revealed thrombospondin-2 to be upregulated in distal cholangiocarcinoma epithelial and stromal compartments. In paired lymph node metastases samples, thrombospondin-2 expression was significantly lower; however, stromal thrombospondin-2 expression was still frequent (72%). Stromal thrombospondin-2 was an independent predictor of poor disease-free survival (HR 3.95, 95% CI 1.09–14.3; P = 0.037).

Conclusion

Several proteins without prior association with distal cholangiocarcinoma biology were identified and verified as differentially expressed between distal cholangiocarcinoma and normal bile duct samples. These proteins can be further evaluated to elucidate their biomarker potential and role in distal cholangiocarcinoma carcinogenesis. Stromal thrombospondin-2 is a potential prognostic marker in distal cholangiocarcinoma.

Cross-Species Proteomics Identifies CAPG and SBP1 as Crucial Invasiveness Biomarkers in Rat and Human Malignant Mesothelioma

Malignant mesothelioma (MM) still represents a devastating disease that is often detected too late, while the current effect of therapies on patient outcomes remains unsatisfactory. Invasiveness biomarkers may contribute to improving early diagnosis, prognosis, and treatment for patients, a task that could benefit from the development of high-throughput proteomics. To limit potential sources of bias when identifying such biomarkers, we conducted cross-species proteomic analyzes on three different MM sources. Data were collected firstly from two human MM cell lines, secondly from rat MM tumors of increasing invasiveness grown in immunocompetent rats and human MM tumors grown in immunodeficient mice, and thirdly from paraffin-embedded sections of patient MM tumors of the epithelioid and sarcomatoid subtypes. Our investigations identified three major invasiveness biomarkers common to the three tumor sources, CAPG, FABP4, and LAMB2, and an additional set of 25 candidate biomarkers shared by rat and patient tumors. Comparing the data to proteomic analyzes of preneoplastic and neoplastic rat mesothelial cell lines revealed the additional role of SBP1 in the carcinogenic process. These observations could provide new opportunities to identify highly vulnerable MM patients with poor survival outcomes, thereby improving the success of current and future therapeutic strategies.

Prognostic and clinicopathological significance of CapG in various cancers: Evidence from a meta-analysis

BACKGROUND

The gelsolin-like actin-capping protein (CapG) is an actin-binding protein in the gelsolin superfamily. Increasing evidence indicates that CapG is highly expressed in various types of cancer. However, the role of CapG in malignant tumors is still controversial. Therefore, we conducted a meta-analysis to assess the prognostic value and clinicopathological significance of CapG in malignant tumors.

METHOD

We searched for eligible studies in the PubMed, Web of Science, Embase, and Cochrane databases. Stata SE12.0 software was used for quantitative meta-analysis. The hazard ratios (HRs) and odds ratios (ORs) with 95% CI were pooled to assess the relationship between CapG expression and overall survival (OS), as well as clinicopathological parameters.

RESULTS

Sixteen studies with a total of 1987 cancer patients were included in this meta-analysis. The results showed that higher CapG expression was statistically correlated with shorter OS (HR 1.70, 95% CI 1.43-1.97, P < 0.001), positive lymph node metastasis (OR 1.91, 95% CI 1.19-3.09, P =  0.008), advanced TNM stage (OR 1.87, 95% CI 1.17-3.00, P = 0.009), advanced T-primary stage (OR 2.54, 95% CI 1.08-6.00, P =  0.033) and male sex (OR 1.77, 95% CI 1.23-2.56, P =  0.002). However, no significant correlation was observed between increased CapG expression and advanced age, larger tumor size, differentiation, or advanced histopathologic grading (P > 0.05).

CONCLUSIONS

High CapG expression is associated with a poor prognosis and worse clinicopathological parameters in various cancers. CapG is a potential prognostic biomarker and a possible clinicopathological predictive factor for various cancers.

Cancer biomarker development and two-dimensional difference gel electrophoresis (2D-DIGE)

Cancer results from the accumulation of genomic alterations. As the genome is functionally translated to the proteome and regulates tumor cell behavior, proteomics studies are expected to further the current understanding of the molecular mechanisms underlying carcinogenesis and cancer progression. Biomarkers are potential tools to classify cancers for therapy, predict responses to treatments, and support treatment-related decision-making. Biomarker development has been actively pursued in oncology by proteomic approaches. Two-dimensional difference gel electrophoresis (2D-DIGE) is a proteomics technique based on two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). In 2D-DIGE, protein samples are labeled with distinct fluorescent dyes before fractionation via 2D-PAGE. 2D-DIGE offers advantages to identify biomarker candidates, including reproducibility, high sensitivity, comprehensiveness, and high throughput. 2D-DIGE has contributed to the establishment of tissue biomarkers, which potentially facilitate precision medicine. 2D-DIGE is thus expected to yield major advancements in cancer biomarker identification and development.

Function of the macrophage-capping protein in colorectal carcinoma

To investigate the role of macrophage-capping protein (CapG) in the development and progression of colorectal carcinoma (CRC), immunohistochemistry (IHC), Kaplan-Meier survival analysis, wound healing and Transwell migration assays were performed. The IHC results demonstrated that CapG was relatively highly expressed in CRC tissue compared with non-tumor tissue (P<0.001), and that the expression of CapG was significantly associated with the tumor site, differentiation, lymph node metastasis and clinical stage (P=0.021, P=0.036, P=0.012 and P=0.009, respectively). Wound healing and Transwell migration assays demonstrated that the reduction of CapG expression in a CRC cell line by RNA interference was associated with significantly impaired motility (P<0.001). Kaplan-Meier survival analysis revealed that the expression of CapG in tumor samples was not significantly associated with disease-free survival time. In conclusion, CapG was overexpressed in CRC and was associated with tumor progression; therefore, it may be a useful prognostic biomarker and therapeutic target in CRC.

Establishment of various biliary tract carcinoma cell lines and xenograft models for appropriate preclinical studies

We recently reported several driver genes of biliary tract carcinoma (BTC) that are known to play important roles in oncogenesis and disease progression. Although the need for developing novel therapeutic strategies is increasing, there are very few BTC cell lines and xenograft models currently available for conducting preclinical studies. Using a total of 88 surgical BTC specimens and 536 immunodeficient mice, 28 xenograft models and 13 new BTC cell lines, including subtypes, were established. Some of our cell lines were found to be resistant to gemcitabine, which is currently the first choice of treatment, thereby allowing highly practical preclinical studies to be conducted. Using the aforementioned cell lines and xenograft models and a clinical pathological database of patients undergoing BTC resection, we can establish a preclinical study system and appropriate parameters for drug efficacy studies to explore new biomarkers for practical applications in the future studies.

Proteomic identification of predictive tissue biomarkers of sensitive to neoadjuvant chemotherapy in squamous cervical cancer

AIMS

The regimens of neoadjuvant chemotherapy (NAC) in squamous cervical cancer (SCC) frequently use cisplatin combined with paclitaxel. Unfortunately, some cervical cancers show resistance to the principal chemotherapeutic agents in the treatment, decreasing the effectiveness of this therapy. The objective of this study was to search for predictive markers of response to NAC in patients with SCC.

MAIN METHODS

Two-dimensional gel electrophoresis (2-DE) accompanied by matrix-assisted laser desorption ionization time-of-flight tandem mass spectrometry (MALDI-TOF-MS) was used to analyze and identify differentially expressed proteins in ten cases of advanced cervical cancer patients receiving cisplatin-based NAC. Each of these patients received more than two cycles of NAC. Cell proliferation rate in cisplatin resistant human cervical cancer cell Hela/DDP and its parent cell Hela after treatment with Hsp70 inhibitor and/or cisplatin were tested by MTT assay.

KEY FINDINGS

Twelve protein spots changed in abundance, quantitative comparison of spot volumes showed that seven protein spots were up-regulated and five spots were down-regulated in the NAC non-responders compared to the NAC responders. These proteins are involved in various cellular processes essential for cell metabolism, migration and apoptotic signal transduction. The high-fold changes proteins of stathmin1, Hsp70 and pyruvate kinase isoform M2 were validated by Western blot analysis. Over-expression of Hsp70 inhibits the efficacy of cisplatin. Hsp70 inhibitor enhanced the sensitivity to cisplatin in both Hela and Hela/DDP cells.

SIGNIFICANCE

The study found many candidate proteins involved in chemotherapy resistance/sensitivity, among them Hsp70 might be potential biomarkers to predict the efficacy of chemotherapy for SCC patients.

Identification of novel biomarker candidates for the immunohistochemical diagnosis of cholangiocellular carcinoma

The aim of this study was the identification of novel biomarker candidates for the diagnosis of cholangiocellular carcinoma (CCC) and its immunohistochemical differentiation from benign liver and bile duct cells. CCC is a primary cancer that arises from the epithelial cells of bile ducts and is characterized by high mortality rates due to its late clinical presentation and limited treatment options. Tumorous tissue and adjacent non-tumorous liver tissue from eight CCC patients were analyzed by means of two-dimensional differential in-gel electrophoresis and mass-spectrometry-based label-free proteomics. After data analysis and statistical evaluation of the proteins found to be differentially regulated between the two experimental groups (fold change ≥ 1.5; p value ≤ 0.05), 14 candidate proteins were chosen for determination of the cell-type-specific expression profile via immunohistochemistry in a cohort of 14 patients. This confirmed the significant up-regulation of serpin H1, 14-3-3 protein sigma, and stress-induced phosphoprotein 1 in tumorous cholangiocytes relative to normal hepatocytes and non-tumorous cholangiocytes, whereas some proteins were detectable specifically in hepatocytes. Because stress-induced phosphoprotein 1 exhibited both sensitivity and specificity of 100%, an immunohistochemical verification examining tissue sections of 60 CCC patients was performed. This resulted in a specificity of 98% and a sensitivity of 64%. We therefore conclude that this protein should be considered as a potential diagnostic biomarker for CCC in an immunohistochemical application, possibly in combination with other candidates from this study in the form of a biomarker panel. This could improve the differential diagnosis of CCC and benign bile duct diseases, as well as metastatic malignancies in the liver.

New insight into benign tumours of major salivary glands by proteomic approach

Major salivary gland tumours are uncommon neoplasms of the head and neck. The increase of precise pre-operative diagnosis is crucial for their correct management and the identification of molecular markers would surely improve the required accuracy. In this study we performed a comparative proteomic analysis of fine needle aspiration fluids of the most frequent benign neoplasms of major salivary glands, namely pleomorphic adenoma and Warthin's tumour, in order to draw their proteomic profiles and to point out their significant features. Thirty-five patients submitted to parotidectomy were included in the study, 22 were identified to have pleomorphic adenoma and 14 Warthin's tumour. Fine needle aspiration samples were processed using a two-dimensional electrophoresis/mass spectrometry-based approach. A total of 26 differentially expressed proteins were identified. Ingenuity software was used to search the biological processes to which these proteins belong and to construct potential networks. Intriguingly, all Warthin's tumour up-regulated proteins such as Ig gamma-1 chain C region, Ig kappa chain C region and Ig alpha-1 chain C region and S100A9 were correlated to immunological and inflammatory diseases, while pleomorphic adenomas such as annexin A1, annexin A4, macrophage-capping protein, apolipoprotein E and alpha crystalline B chain were associated with cell death, apoptosis and tumorigenesis, showing different features of two benign tumours. Overall, our results shed new light on the potential usefulness of a proteomic approach to study parotid tumours and in particular up regulated proteins are able to discriminate two types of benign parotid lesions.

Laser microdissection and two-dimensional difference gel electrophoresis reveal the role of a novel macrophage-capping protein in lymph node metastasis in gastric cancer

To reveal the proteomic background of lymph node metastasis (LNM) in gastric cancer, we performed a proteomic study of tumor and matched nontumor tissues obtained from surgically resected specimens of 22 patients with or without LNM. Using laser microdissection, we recovered specific populations of tumor and nontumor cells. We used two-dimensional difference gel electrophoresis with a large format electrophoresis apparatus to obtain protein expression profiles consisting of 3228 protein spots, and we classified them according to their expression pattern. We found that macrophage-capping protein (CapG) was up-regulated in the tumor tissues of patients with LNM, whereas it showed an equivalent expression level between nontumor and tumor tissues of patients without LNM. It was reported that CapG associated with invasion and metastasis in various malignancies. However, CapG was not investigated in gastric cancer until our study. Western blotting of the laser microdissected tissue samples confirmed up-regulation of CapG in the tumor tissues of patients with LNM. Functional assays demonstrated that CapG promoted tumor cell invasion, but not cell proliferation. The association between CapG expression and LNM is a novel finding in gastric cancer. Further investigation for a prognostic utility of CapG may lead to a risk stratification therapy for gastric cancer.

Proteomic identification of the macrophage-capping protein as a protein contributing to the malignant features of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most deadly cancers worldwide. We performed a proteomic study to understand the molecular mechanisms underlying metastasis in HCC. Among the 3491 protein spots observed by two-dimensional difference gel electrophoresis (2D-DIGE), we found that 197 and 88 protein spots had statistically significant differences in intensity between tumor and non-tumor tissues and between the tumors with and without vascular invasion, respectively. Mass spectrometry was used to identify the proteins corresponding to those protein spots. We found that compared to tumor tissues without vascular invasion, those with vascular invasion showed markedly upregulated expression of the macrophage-capping protein (CapG). The association of increased CapG expression with vascular invasion in the tumor tissues was confirmed by western blotting. CapG expression levels were equal for non-tumor tissues and tumor tissues without venous invasion, as assessed by 2D-DIGE and western blotting. Silencing of CapG reduced tumor invasion without affecting the proliferation of the HCC cells. These observations suggested that CapG is involved in the process of metastasis by promoting the invasiveness of tumor cells. It may therefore be worth investigating the clinical usefulness of CapG as a biomarker in risk-stratification therapy and as a therapeutic target in HCC.