Characterisation and protein expression profiling of annexins in colorectal cancer

Quantitative analysis of self-association and mobility of annexin A4 at the plasma membrane

Annexins, found in most eukaryotic species, are cytosolic proteins that are able to bind negatively-charged phospholipids in a calcium-dependent manner. Annexin A4 (AnxA4) has been implicated in diverse cellular processes, including the regulation of exocytosis and ion-transport; however, its precise mechanistic role is not fully understood. AnxA4 has been shown to aggregate on lipid layers upon Ca(2+) binding in vitro, a characteristic that may be critical for its function. We have utilized advanced fluorescence microscopy to discern details on the mobility and self-assembly of AnxA4 after Ca(2+) influx at the plasma membrane in living cells. Total internal reflection microscopy in combination with Förster resonance energy transfer reveals that there is a delay between initial plasma membrane binding and the beginning of self-assembly and this process continues after the cytoplasmic pool has completely relocated. Number-and-brightness analysis suggests that the predominant membrane bound mobile form of the protein is trimeric. There also exists a pool of AnxA4 that forms highly immobile aggregates at the membrane. Fluorescence recovery after photobleaching suggests that the relative proportion of these two forms varies and is correlated with membrane morphology.

Annexin A4 is involved in proliferation, chemo-resistance and migration and invasion in ovarian clear cell adenocarcinoma cells

Ovarian clear cell adenocarcinoma (CCC) is the second most common subtype of ovarian cancer after high-grade serous adenocarcinomas. CCC tends to develop resistance to the standard platinum-based chemotherapy, and has a poor prognosis when diagnosed in advanced stages. The ANXA4 gene, along with its product, a Ca⁺⁺-binding annexin A4 (ANXA4) protein, has been identified as the CCC signature gene. We reported two subtypes of ANXA4 with different isoelectric points (IEPs) that are upregulated in CCC cell lines. Although several in vitro investigations have shown ANXA4 to be involved in cancer cell proliferation, chemoresistance, and migration, these studies were generally based on its overexpression in cells other than CCC. To elucidate the function of the ANXA4 in CCC cells, we established CCC cell lines whose ANXA4 expressions are stably knocked down. Two parental cells were used: OVTOKO contains almost exclusively an acidic subtype of ANXA4, and OVISE contains predominantly a basic subtype but also a detectable acidic subtype. ANXA4 knockdown (KO) resulted in significant growth retardation and greater sensitivity to carboplatin in OVTOKO cells. ANXA4-KO caused significant loss of migration and invasion capability in OVISE cells, but this effect was not seen in OVTOKO cells. We failed to find the cause of the different IEPs of ANXA4, but confirmed that the two subtypes are found in clinical CCC samples in ratios that vary by patient. Further investigation to clarify the mechanism that produces the subtypes is needed to clarify the function of ANXA4 in CCC, and might allow stratification and improved treatment strategies for patients with CCC.

Potential role of Anxa1 in cancer

The annexins are a well-known, closely related, multigene superfamily of Ca2+-regulated, phospholipid-dependent, membrane-binding proteins. As a member of the annexins, Anxa1 participates in a variety of important biological processes, such as cellular transduction, membrane aggregation, inflammation, phagocytosis, proliferation, differentiation and apoptosis. Accumulated evidence has indicated that Anxa1 deregulations are associated with the development, invasion, metastasis, occurrence and drug resistance of cancers. The research evidence in recent years indicates that Anxa1 might specifically function either as a tumor suppressor or a tumor promoter candidate for certain cancers depending on the particular type of tumor cells/tissues. This article summarizes the associations between Anxa1 and malignant tumors, as well as potential action mechanisms. Anxa1 has the potential to be used in the future as a biomarker for the diagnosis, treatment and prognosis of certain tumors.

Annexin A4-conferred platinum resistance is mediated by the copper transporter ATP7A

Although platinum drugs are often used for the chemotherapy of human cancers, platinum resistance is a major issue and may preclude their use in some cases. We recently reported that enhanced expression of Annexin A4 (Anx A4) increases chemoresistance to carboplatin through increased extracellular efflux of the drug. However, the precise mechanisms underlying that chemoresistance and the relationship of Anx A4 to platinum resistance in vivo remain unclear. In this report, the in vitro mechanism of platinum resistance induced by Anx A4 was investigated in endometrial carcinoma cells (HEC1 cells) with low expression of Anx A4. Forced expression of Anx A4 in HEC1 cells resulted in chemoresistance to platinum drugs. In addition, HEC1 control cells were compared with Anx A4-overexpressing HEC1 cells in xenografted mice. Significantly greater chemoresistance to cisplatin was observed in vivo in Anx A4-overexpressing xenografted mice. Immunofluorescence analysis revealed that exposure to platinum drugs induced relocation of Anx A4 from the cytoplasm to the cellular membrane, where it became colocalized with ATP7A, a copper transporter also well known as a mechanism of platinum efflux. ATP7A expression suppressed by small interfering RNA had no effect on HEC1 control cells in terms of chemosensitivity to platinum drugs. However, suppression of ATP7A in Anx A4-overexpressing platinum-resistant cells improved chemosensitivity to platinum drugs (but not to 5-fluorouracil) to a level comparable to that of control cells. These results indicate that enhanced expression of Anx A4 confers platinum resistance by promoting efflux of platinum drugs via ATP7A.

Aberrant O-GlcNAc-modified proteins expressed in primary colorectal cancer

O-GlcNAcylation is a post-translational modification of serine and threonine residues which is dynamically regulated by 2 enzymes; O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA) that catalyze the addition and removal of a single N-acetylglucosamine (GlcNAc) molecule, respectively. This modification is thought to be a nutrient sensor in highly proliferating cells via the hexosamine biosynthesis pathway, a minor branch of glycolysis. Although emerging evidence suggests that O-GlcNAc modification is associated with many types of cancer, identification of O-GlcNAc-modified proteins and their role in cancer remain unexplored. In the present study, we demonstrated that O-GlcNAcylation is increased in primary colorectal cancer tissues, and that this augmentation is associated with an increased expression of OGT levels. Using 2-dimensional O-GlcNAc immunoblotting and LC-MS/MS analysis, 16 proteins were successfully identified and 8 proteins showed an increase in O-GlcNAcylation, including cytokeratin 18, heterogeneous nuclear ribonucleoproteins A2/B1 (hnRNP A2/B1), hnRNP H, annexin A2, annexin A7, laminin-binding protein, α-tubulin and protein DJ-1. Among these identified proteins, annexin A2 was further confirmed to show overexpression of O-GlcNAc in all cancer samples. The results, therefore, indicate that aberrant O-GlcNAcylation of proteins is associated with colorectal cancer and that identification of O-GlcNAc-modified proteins may provide novel biomarkers of cancer.

Gene expression profiling of serrated polyps identifies annexin A10 as a marker of a sessile serrated adenoma/polyp

Sessile serrated adenomas/polyps (SSA/Ps) are precursors of colon cancer, particularly those that exhibit microsatellite instability. Distinguishing SSA/Ps from the related, but innocuous, microvesicular hyperplastic polyp (MVHP) can be challenging. In this study seven gastrointestinal pathologists reviewed 109 serrated polyps and identified 60 polyps with histological consensus. Microarray analysis was performed on six distal consensus MVHPs < 9 mm, six proximal consensus SSA/Ps > 9 mm, and six normal colon biopsies (three proximal, three distal). Comparative gene expression analysis confirmed the close relationship between SSA/Ps and MVHPs as there was overlapping expression of many genes. However, the gene expression profile in SSA/Ps had stronger and more numerous associations with cancer-related genes compared with MVHPs. Three genes (TFF2, FABP6, and ANXA10) were identified as candidates whose expression can differentiate SSA/Ps from MVHPs, and the differences in expression were confirmed by quantitative RT-PCR. As ANXA10 showed the most promise in differentiating these polyps, the expression of ANXA10 was evaluated by immunohistochemistry in consensus SSA/Ps (n = 26), MVHPs (n = 21), and normal colon (n = 9). Immunohistochemical expression of ANXA10 was not identified in separate samples of normal colon or in the normal colonic epithelium adjacent to the serrated polyps. Consistent with the microarray and quantitative RT-PCR experiments, immunohistochemical expression of ANXA10 was markedly increased in SSA/Ps compared to MVHPs (p < 0.0001). An ANXA10 score ≥ 3 has a sensitivity of 73% and a specificity of 95% in the diagnosis of an SSA/P. In conclusion, we show that SSA/Ps and MVHPs have significant overlap in gene expression, but also important differences, particularly in cancer-related pathways. Expression of ANXA10 may be a potential marker of the serrated pathway to colon cancer.

Prognostic and diagnostic significance of annexin A2 in colorectal cancer

AIM

Annexin A2 (ANXA2) is known to be a tumourigenic molecule and is highly expressed in colorectal cancer (CRC). Its diagnostic and prognostic value is not fully understood. This study was designed to investigate the relationship between ANXA2 expression, clinicopathological characteristics, tumour recurrence and survival.

METHOD

Immunohistochemical staining was used to evaluate ANXA2 expression in 150 matched samples from patients with CRC. Overall survival and recurrence were determined by Kaplan-Meier analysis. The Cox proportional hazards model was used to determine independent factors contributing to survival and recurrence. Receiver operating characteristic (ROC) curve and liner correlation analysis were used to estimate the sensitivity and specificity of ANXA2 expression for clinical diagnosis.

RESULTS

ANXA2 was found to be strongly expressed in poorly differentiated tumours (P < 0.001), late stage (P = 0.020) and lymph node positivity (P = 0.002). ANXA2 expression was significantly related to recurrence (P < 0.001) and survival (P = 0.002). The Cox proportional hazards model indicated that ANXA2 expression [P < 0.001, hazard ratio (HR) = 1.366, 95% CI 1.232-1.515] and tumour location (P = 0.039, HR = 1.891, 95% CI 1.034-3.456) were independent factors in predicting overall survival while ANXA2 expression (P < 0.001, HR = 1.445, 95% CI 1.222-1.709) were independent factors predicting recurrence. Receiver operating characteristic (ROC) (AUC = 0.768, 95% CI = 0.642-0.894) and liner correlation analysis suggested that ANXA2 was suitable for the clinical diagnosis of CRC.

CONCLUSION

These results indicate that ANXA2 is a biomarker with diagnostic and prognostic potential for patients with CRC.

ROS production and NF-κB activation triggered by RAC1 facilitate WNT-driven intestinal stem cell proliferation and colorectal cancer initiation

The Adenomatous Polyposis Coli (APC) gene is mutated in the majority of colorectal cancers (CRCs). Loss of APC leads to constitutively active WNT signaling, hyperproliferation, and tumorigenesis. Identification of pathways that facilitate tumorigenesis after APC loss is important for therapeutic development. Here, we show that RAC1 is a critical mediator of tumorigenesis after APC loss. We find that RAC1 is required for expansion of the LGR5 intestinal stem cell (ISC) signature, progenitor hyperproliferation, and transformation. Mechanistically, RAC1-driven ROS and NF-κB signaling mediate these processes. Together, these data highlight that ROS production and NF-κB activation triggered by RAC1 are critical events in CRC initiation.

Expression of neutrophil gelatinase-associated lipocalin in colorectal neoplastic progression: a marker of malignant potential?

Background:

Neutrophil gelatinase-associated lipocalin (NGAL) has a diverse functional repertoire, involved in the innate immune response as well as cell growth and differentiation. Expression has been linked to malignant disease development and progression.

Methods:

Neutrophil gelatinase-associated lipocalin expression was assessed immunohistochemically in 98 colorectal neoplastic lesions (52 cancer polyps (CaPs) and 46 sporadic adenoma/adjacent normal mucosa paired specimens) to investigate association with adenoma progression and early colorectal carcinogenesis.

Results:

Within CaPs, all adenomatous and carcinomatous epithelium expressed NGAL, with 92% (43 out of 47) and 58% (19 out of 33) epithelial positivity, respectively, as well as positive stromal cell expression. This was significantly increased compared with normal mucosal epithelium (P=0.0001). Neutrophil gelatinase-associated lipocalin positivity was also identified in sporadic low-grade adenomas, in both the epithelial and stromal compartments as compared with adjacent normal mucosa (P=0.0001 and 0.0002), and this increased along with adenoma size >1 cm (P=0.03).

Conclusion:

Neutrophil gelatinase-associated lipocalin is expressed by the majority of human neoplastic colorectal lesions. This phenotypic switch occurs at an early stage in neoplastic progression with clear differential expression between normal mucosa and adenomatous polyps, rather than further downstream in disease progression at the adenoma–carcinoma transformation. Thus, NGAL expression is not a useful biomarker for determining disease progression from adenomatous to malignant colorectal neoplasia.

Glycoproteomic analysis of tissues from patients with colon cancer using lectin microarrays and nanoLC-MS/MS

The current study evaluated the glycoproteomic profile of tissues from colon cancer patients. The lectin microarray was first performed to compare the glycoprotein profiles between colon cancer and matched normal tissues. Level of N-acetylglucosamine (GlcNAc) that Solanum tuberosum lectin (STL) bound was found to be elevated in colon cancer, which was verified through lectin histochemistry. The subsequent glycoproteomic analysis based on STL enrichment of glycoproteins followed by label-free quantitative nano liquid chromatography-mass spectrometry/mass spectrometry (nanoLC-MS/MS) analysis identified 72 proteins in high confidence. Among these proteins, 17 were exclusively detected in cancer tissues, and 14 were significantly upregulated in tumor tissues. Annexin A1 and HSP90β were chosen for further investigation by immunoprecipitation coupled with lectin blots, western blots and tissue microarrays. Both Annexin A1 and HSP90β were GlcNAcylated, and their protein expressions were elevated in colon cancer, compared to normal tissues. Moreover, specific changes of GlcNAc abundances in Annexin A1 and HSP90β suggested that tumor-specific glycan patterns could serve as candidate biomarkers of colon cancer for distinguishing cancer patients from healthy individuals.

Discovery of potential targets of selenomethionine-mediated chemoprevention in colorectal carcinoma mouse model using proteomics analysis

Despite some controversy, selenomethionine (SeMet)-mediated protection against colorectal cancer (CRC) might be a very promising non-cytotoxic option. However, responsive molecular targets and underlying mechanisms of SeMet-mediated chemoprevention are still unclear. Our aim was to discover new targets of SeMet-mediated chemoprevention in CRC using proteomics analysis. We found dietary SeMet supplementation before carcinoma initiation effectively suppressed polyp incidence and dysplastic lesions without any adverse effects. To determine chemopreventive targets of SeMet, we employed two-dimensional gel electrophoresis-based proteomics analysis in CRC mouse model. Pretreatment with SeMet apparently modulated the expression of 30 proteins with functions in major processes like chronic inflammation, oxidative stress and apoptosis as discovered through pathway analysis with Pathway Studio software. We validated four proteins selected from pathway analysis including prohibitin, purine nucleoside phosphorylase, annexin 2 and c-reactive protein by immunohistochemistry. 8-Hydroxy-2'-deoxyguanosine (8-OHdG), a known oxidative stress marker, was decreased by SeMet treatment in CRC mice as seen by immunohistochemistry. Further network analysis was done among these new four validated proteins, 8-OHdG and colorectal cancer. These four proteins found by proteomics analysis might be considered as potential chemopreventive biomarkers of SeMet against colon cancer and can help develop and improve approaches in preventive, therapeutic and prognostic aspects.

Overexpression of annexin A4 is associated with chemoresistance in papillary serous adenocarcinoma of the ovary

Annexin A4 study in ovarian cancer has been primarily focused on clear cell carcinoma, which exhibits strong resistance to chemotherapy. The aim of this study was to examine the expression and cellular localization of annexin A4 in serous ovarian carcinomas. We evaluated the expression of annexin A4 with real-time polymerase chain reaction in 40 ovarian serous carcinoma tissues. Furthermore, the distribution of the protein within the tumor was studied by immunohistochemistry in 70 epithelial ovarian carcinoma tissues. The levels of annexin A4 transcripts were higher in 14 chemoresistant tumors than those in 26 chemosensitive tumors (P = .013). Immunohistochemical expressions showed that nuclear expression was detected in 14 (20.0%) of 70 samples, and cytoplasmic expression was detected in 17 (24.3%) of 70 samples. The results showed that 35.7% of women with nuclear expression were resistant to platinum-based chemotherapy, whereas only 14.3% of women without expression were chemoresistant (P = .065). In addition, patients with nuclear staining had significantly shorter disease-free survival than did patients who showed negative staining. Multivariate proportional hazards model revealed that the stage and nuclear annexin A4 expression were independent prognostic factors (hazard ratios, 6.34 [P = .001] and 2.85 [P = .011], respectively). This study showed that overexpression and nuclear localization of annexin A4 are related to chemoresistance and poor survival in patients with serous papillary ovarian carcinomas. Future studies are required to develop new therapies targeting annexin A4 in patients with ovarian epithelial adenocarcinoma.

Lysyl oxidase plays a critical role in endothelial cell stimulation to drive tumor angiogenesis

Identification of key molecules that drive angiogenesis is critical for the development of new modalities for the prevention of solid tumor progression. Using multiple models of colorectal cancer, we show that activity of the extracellular matrix-modifying enzyme lysyl oxidase (LOX) is essential for stimulating endothelial cells in vitro and angiogenesis in vivo. We show that LOX activates Akt through platelet-derived growth factor receptor β (PDGFRβ) stimulation, resulting in increased VEGF expression. LOX-driven angiogenesis can be abrogated through targeting LOX directly or using inhibitors of PDGFRβ, Akt, and VEGF signaling. Furthermore, we show that LOX is clinically correlated with VEGF expression and blood vessel formation in 515 colorectal cancer patient samples. Finally, we validate our findings in a breast cancer model, showing the universality of these observations. Taken together, our findings have broad clinical and therapeutic implications for a wide variety of solid tumor types.

Lysyl oxidase plays a critical role in endothelial cell stimulation to drive tumor angiogenesis

Identification of key molecules that drive angiogenesis is critical for the development of new modalities for the prevention of solid tumor progression. Using multiple models of colorectal cancer, we show that activity of the extracellular matrix-modifying enzyme lysyl oxidase (LOX) is essential for stimulating endothelial cells in vitro and angiogenesis in vivo. We show that LOX activates Akt through platelet-derived growth factor receptor β (PDGFRβ) stimulation, resulting in increased VEGF expression. LOX-driven angiogenesis can be abrogated through targeting LOX directly or using inhibitors of PDGFRβ, Akt, and VEGF signaling. Furthermore, we show that LOX is clinically correlated with VEGF expression and blood vessel formation in 515 colorectal cancer patient samples. Finally, we validate our findings in a breast cancer model, showing the universality of these observations. Taken together, our findings have broad clinical and therapeutic implications for a wide variety of solid tumor types.

Proteomics-based analysis of invasion-related proteins in malignant gliomas

One of the insidious biological features of gliomas is their potential to extensively invade normal brain tissue, yet molecular mechanisms that dictate this locally invasive behavior remain poorly understood. To investigate the molecular basis of invasion by malignant gliomas, proteomic analysis was performed using a pair of canine glioma subclones - J3T-1 and J3T-2 - that show different invasion phenotypes in rat brains but have similar genetic backgrounds. Two-dimensional protein electrophoresis of whole-cell lysates of J3T-1 (angiogenesis-dependent invasion phenotype) and J3T-2 (angiogenesis-independent invasion phenotype) was performed. Twenty-two distinct spots were recognized when significant alteration was defined as more than 1.5-fold change in spot intensity between J3T-1 and J3T-2. Four proteins that demonstrated increased expression in J3T-1, and 14 proteins that demonstrated increased expression in J3T-2 were identified using liquid chromatography-mass spectrometry analysis. One of the proteins identified was annexin A2, which was expressed at higher levels in J3T-1 than in J3T-2. The higher expression of annexin A2 in J3T-1 was corroborated by quantitative RT-PCR of the cultured cells and immunohistochemical staining of the rat brain tumors. Moreover, immunohistochemical analysis of human glioblastoma specimens showed that annexin A2 was expressed at high levels in the tumor cells that formed clusters around dilated vessels. These results reveal differences in the proteomic profiles between these two cell lines that might correlate with their different invasion profiles. Thus, annexin A2 may be related to angiogenesis-dependent invasion.

Correlation of expression levels of ANXA2, PGAM1, and CALR with glioma grade and prognosis

OBJECT

Biomarkers for the diagnosis and prognosis of gliomas are lacking. To elucidate new diagnostic and prognostic targets, a routine method is used to evaluate differences between the protein profile of normal and tumor cells. The object of the current study was to investigate novel differentially expressed proteins and their roles in gliomas.

METHODS

Differences in the protein profile were compared using 2D polyacrylamide gel electrophoresis using C6 glioma cells and rat astrocytes. The mRNA and protein expression of ANXA2, PGAM1, and CALR were analyzed in glioma tissues and normal brain tissues. The expression of ANXA2 in the U87 glioma cell line was interrupted using short interfering RNA duplexes, and the role of ANXA2 in the migration and invasiveness of glioma cells was assessed. The expression of ANXA2, PGAM1, and CALR was examined further by immunohistochemical analysis using 130 glioma samples obtained in patients, and their prognostic roles in gliomas were evaluated using Kaplan-Meier and Cox regression analyses.

RESULTS

Significantly higher expression levels of ANXA2 and PGAM1 and a lower level of CALR were found in glioma samples than in the normal brain samples. ANXA2, PGAM1, and CALR expression correlated with the grade and survival of patients with gliomas. Multivariate analysis further revealed that ANXA2 was an independent prognostic marker for glioma. After ANXA2 expression was suppressed using short interfering RNA, U87 cells had decreased migratory and invasive capabilities in vitro.

CONCLUSIONS

Protein expression alterations in ANXA2, PGAM1, and CALR were found in gliomas, and ANXA2 provided a novel prognostic value.

Annexin A1, A2, A4 and A5 play important roles in breast cancer, pancreatic cancer and laryngeal carcinoma, alone and/or synergistically

Annexins are associated with metastasis and infiltration of cancer cells. Proteomic analysis and immunohistochemical staining were used to understand whether several annexins play important roles in cancer alone and/or synergistically. Seven fresh breast cancer samples with 23 paraffin specimens, three fresh pancreatic samples and five fresh laryngeal carcinoma samples with 25 paraffin specimens were obtained from humans, as well as ten golden hamster pancreatic cancer tissue samples, and they were used to observe differential expression of annexins compared with normal tissues using proteomics and immunohistochemical staining. Annexin A2, A4 and A5 were overexpressed in human breast cancer and laryngeal carcinoma tissues and in golden hamster pancreatic cancer tissue samples, respectively, as shown by proteomics and immunohistochemical staining. In addition, annexin A4 and A5 were expressed in breast cancer tissues, while annexin A1 was not expressed. Annexin A1, A2 and A4 were expressed in human laryngeal carcinoma tissues as shown by immunohistochemical staining. Annexin A1, A2, A4 and A5 played important roles in breast cancer, pancreatic cancer and laryngeal carcinoma, alone and/or synergistically, and they may be targets of therapy for malignant tumors. The choice of which annexins to target should depend on their respective biological behaviors.

New prognosis biomarkers identified by dynamic proteomic analysis of colorectal cancer

The initiation, promotion and progression of human cancer are complex, polygenic, multi-factored processes. Through systematic proteomic analysis, different stages of CRC (colorectal cancer) biopsies were examined, and 199 differentially expressed proteins were detected between TNM (the tumor, nodes, and metastasis) stages I-IV and normal tissue (One-Way Analysis of Variance, ANOVA; p≤ 0.05). Instead of looking for biomarkers to distinguish CRC from normal or identify metastatic tumors, we focused on the variation tendency of CRC carcinogenesis and the dynamic expression patterns of proteins among the different stages. Som (self-organizing map clustering) analysis revealed eight unique expression patterns and that the cancer-related proteins were dynamically expressed, and their expression levels changed continuously throughout tumorigenesis. Molecular evidence emerged much earlier than visible, clinical or histological changes, which shows the potential prospect of building molecular staging. Proteins identified by MALDI-TOF MS (Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry) were mainly involved in energy metabolism, acetylation and signaling pathways. Validation experiments using immunoblotting and immunohistochemistry (IHC) agreed with the 2D-DIGE (two-dimensional difference in gel electrophoresis) data. After survival classifier and LOOCV (leave-one-out cross-validation) analyses, the new prognostic biomarkers (78 kDa Glucose-Regulated Protein precursor (GRP78), Fructose-bisphosphate Aldolase A (ALDOA), Carbonic Anhydrase I (CA1) and Peptidyl-prolyl cis-trans isomerase A or Cyclophilin A (PPIA)) provided good survival prediction for TNM stage I-IV patients. The new biomarkers derived from the dynamic patterns of these proteins' expression provide is a good supplementary method for determining prognosis for CRC, especially for the TNM stage III and IV patients.

Annexin A5 protein expression is associated with the histological differentiation of uterine cervical squamous cell carcinoma in patients with an increased serum concentration

Annexin A5 (ANXA5) is a calcium-dependent phospholipid-binding protein belonging to the annexin family and is expressed abnormally in several types of carcinoma. In the present study, ANXA5 protein expression was evaluated by western blot analysis in a series of 60 human uterine cervical squamous cell carcinomas (UCSCCs) to search for molecular alterations that may be able to serve as useful diagnostic/prognostic markers. The upregulation of ANXA5 expression was observed in 48/60 UCSCC cases (80%), whereas a weak expression was observed in the 25 normal uterine cervical tissues. ANXA5 expression was also analyzed by immunohistochemical staining, western blot and reverse transcription-polymerase chain reaction (RT-PCR) assays of the UCSCC and uterine cervical normal tissue lesions. All dysplastic tissues showed significantly increased ANXA5 expression compared with the weak signal observed in normal epithelia. A close association was observed between the ANXA5 expression levels and the histological grade of UCSCC. Compared with moderately and well-differentiated tumors, there was a significant increase in ANXA5 expression in poorly differentiated tumors. Furthermore, ANXA5 concentrations in the blood serum of the patients were significantly increased. Our findings clearly identify ANXA5 as an effective differentiation marker for the histopathological grading of UCSCCs and for the detection of epithelial dysplasia. The results from our study support the critical role of ANXA5 in the molecular profiling of UCSCC.

Revealing the molecular mechanism of gastric cancer marker annexin A4 in cancer cell proliferation using exon arrays

Gastric cancer is a malignant disease that arises from the gastric epithelium. A potential biomarker for gastric cancer is the protein annexin A4 (ANXA4), an intracellular Ca²⁺ sensor. ANXA4 is primarily found in epithelial cells, and is known to be involved in various biological processes, including apoptosis, cell cycling and anticoagulation. In respect to cancer, ANXA4-overexpression has been observed in cancers of various origins, including gastric tumors associated with Helicobacter pylori infection. H. pylori induces ANXA4 expression and intracellular [Ca²⁺]_i elevation, and is an important risk factor for carcinogenesis that results in gastric cancer. Despite this correlation, the role of ANXA4 in the progression of gastric tumors remains unclear. In this study, we have investigated whether ANXA4 can mediate the rate of cell growth and whether ANXA4 downstream signals are involved in tumorigenesis. After observing the rate of cell growth in real-time, we determined that ANXA4 promotes cell proliferation. The transcription gene profile of ANXA4-overexpressing cells was measured and analyzed by human exon arrays. From this transcriptional gene data, we show that overexpression of ANXA4 regulates genes that are known to be related to cancer, for example the activation of hyaluronan mediated motility receptor (RHAMM), AKT, and cyclin-dependent kinase 1 (CDK1) as well as the suppression of p21. The regulation of these genes further induces cancer cell proliferation. We also found Ca²⁺ could regulate the transmission of downstream signals by ANXA4. We suggest that ANXA4 triggers a signaling cascade, leading to increased epithelial cell proliferation, ultimately promoting carcinogenesis. These results might therefore provide a new insight for gastric cancer therapy, specifically through the modification of ANXA4 activity.

Reciprocal regulation of annexin A2 and EGFR with Her-2 in Her-2 negative and herceptin-resistant breast cancer

Alternative survival pathways are commonly seen to be upregulated upon inhibition of receptor tyrosine kinases (RTK), including Her-2. It is established that treatment with Herceptin leads to selective overexpression and activation of epidermal growth factor receptor (EGFR) and Src which further contributes to oncogenesis in Herceptin resistant and triple negative breast cancer (TNBC) patients. Here, we show a co-regulated upregulation in the expression of Annexin A2 (AnxA2), a known substrate of Src and one of the regulators of EGFR receptor endocytosis, in Herceptin resistant and Her-2 negative breast cancer. Immunohistochemical expression analysis revealed a reciprocal regulation between Her-2 and AnxA2 in breast cancer clinical samples as well as in cell lines as confirmed by protein and RNA analysis. The siRNA and Herceptin mediated downregulation/inhibition of Her-2 in Her-2 amplified cells induced AnxA2 expression and membrane translocation. In this study we report a possible involvement of AnxA2 in maintaining constitutively activated EGFR downstream signaling intermediates and hence in cell proliferation, migration and viability. This effect was consistent in Herceptin resistant JIMT-1 cells as well as in Her-2 negative breast cancer. The siRNA mediated AnxA2 downregulation leads to increased apoptosis, decreased cell viability and migration. Our studies further indicate the role of AnxA2 in EGFR-Src membrane bound signaling complex and ligand induced activation of downstream signaling pathways. Targeting this AnxA2 dependent positive regulation of EGFR signaling cascade may be of therapeutic value in Her-2 negative breast cancer.

A seven-gene signature aggregates a subgroup of stage II colon cancers with stage III

Colorectal cancer is one of the most common cancers in the world. Histological staging is efficient, but combination with molecular markers may improve tumor classification. Gene expression profiles have been defined as prognosis predictors among stage II and III tumors, but their implementation in medical practice remains controversial. Stage II tumors have been recognized as a heterogeneous group, and high-risk morphologic features have been used to justify adjuvant chemotherapy. We propose here the investigation of clinical features and expression profiles from stage II and stage III colon carcinomas without DNA mismatch repair defects. Two series of 130 and 66 colon cancer samples were obtained. Expression profiles were established on oligonucleotide microarrays and processed in the R/Bioconductor environment. Hierarchical, then supervised, analyses were successively performed by applying a data-sampling approach. A molecular signature of seven genes was found to cluster stage III tumors with adjusted p values lower than 10(-10). A subgroup of stage II tumors aggregated this cluster in both series. No correlation was found with disease severity, but the function of the discriminating genes suggests that tumors have been classified according to their putative response to adjuvant targeted or classic therapies. Further pharmacogenetic studies might verify this observation.

Cellular apoptosis susceptibility (chromosome segregation 1-like, CSE1L) gene is a key regulator of apoptosis, migration and invasion in colorectal cancer

Cellular apoptosis susceptibility (chromosome segregation 1-like, CSE1L) gene maps to chromosomal region 20q13.13, a region frequently amplified in solid tumours. In this study, we investigated the roles played by CSE1L in colorectal cancer by examining CSE1L expression and clinico-pathological parameters in colorectal cancer and investigating the effect of CSE1L on the viability, adhesion and migration of colorectal cancer cells. RT-PCR showed that CSE1L mRNA was over-expressed in colorectal cancer. CSE1L depletion by knock-down with CSE1L-specific siRNA significantly reduced viability in HCT116 cells (p = 0.004) and SW480 cells (p = 0.003) whilst significantly increasing the proportion of apoptotic HCT116 cells (p < 0.001) and SW480 cells (p < 0.001). Furthermore, CSE1L depletion significantly reduced the adhesive capacity of HCT116 (p = 0.003) and SW480 cells (p = 0.004). Analysis by qRT-PCR following CSE1L siRNA treatment of HCT116 and SW480 cells showed significant modulation of key apoptotic (p53, p73 and BAK) and adhesive (E-cadherin, Ep-CAM and ICAM-1) molecules. Immunohistochemistry of a colorectal cancer tissue microarray showed that CSE1L had a significantly increased level in colorectal cancer compared to normal colorectal epithelium (p < 0.001). There were significant decreases in both nuclear (p = 0.006) and cytoplasmic (p = 0.003) staining of CSE1L in tumours with lymph node metastasis (stage 3 tumours) compared with lymph node-negative tumours (stage 1 and 2 tumours). In lymph node-negative patients, poor survival was associated with increased CSE1L cytoplasmic expression (p = 0.042). These results indicate that CSE1L is associated with viability and apoptosis, cellular adhesion and invasion, thus implicating CSE1L in the progression of colorectal cancer.

Helicobacter pylori disrupts host cell membranes, initiating a repair response and cell proliferation

Helicobacter pylori (H. pylori), the human stomach pathogen, lives on the inner surface of the stomach and causes chronic gastritis, peptic ulcer, and gastric cancer. Plasma membrane repair response is a matter of life and death for human cells against physical and biological damage. We here test the hypothesis that H. pylori also causes plasma membrane disruption injury, and that not only a membrane repair response but also a cell proliferation response are thereby activated. Vacuolating cytotoxin A (VacA) and cytotoxin-associated gene A (CagA) have been considered to be major H. pylori virulence factors. Gastric cancer cells were infected with H. pylori wild type (vacA+/cagA+), single mutant (ΔvacA or ΔcagA) or double mutant (ΔvacA/ΔcagA) strains and plasma membrane disruption events and consequent activation of membrane repair components monitored. H. pylori disrupts the host cell plasma membrane, allowing localized dye and extracellular Ca(2+) influx. Ca(2+)-triggered members of the annexin family, A1 and A4, translocate, in response to injury, to the plasma membrane, and cell surface expression of an exocytotic maker of repair, LAMP-2, increases. Additional forms of plasma membrane disruption, unrelated to H. pylori exposure, also promote host cell proliferation. We propose that H. pylori activation of a plasma membrane repair is pro-proliferative. This study might therefore provide new insight into potential mechanisms of H. pylori-induced gastric carcinogenesis.

Helicobacter pylori disrupts host cell membranes, initiating a repair response and cell proliferation

Helicobacter pylori (H. pylori), the human stomach pathogen, lives on the inner surface of the stomach and causes chronic gastritis, peptic ulcer, and gastric cancer. Plasma membrane repair response is a matter of life and death for human cells against physical and biological damage. We here test the hypothesis that H. pylori also causes plasma membrane disruption injury, and that not only a membrane repair response but also a cell proliferation response are thereby activated. Vacuolating cytotoxin A (VacA) and cytotoxin-associated gene A (CagA) have been considered to be major H. pylori virulence factors. Gastric cancer cells were infected with H. pylori wild type (vacA+/cagA+), single mutant (ΔvacA or ΔcagA) or double mutant (ΔvacA/ΔcagA) strains and plasma membrane disruption events and consequent activation of membrane repair components monitored. H. pylori disrupts the host cell plasma membrane, allowing localized dye and extracellular Ca²⁺ influx. Ca²⁺-triggered members of the annexin family, A1 and A4, translocate, in response to injury, to the plasma membrane, and cell surface expression of an exocytotic maker of repair, LAMP-2, increases. Additional forms of plasma membrane disruption, unrelated to H. pylori exposure, also promote host cell proliferation. We propose that H. pylori activation of a plasma membrane repair is pro-proliferative. This study might therefore provide new insight into potential mechanisms of H. pylori-induced gastric carcinogenesis.

Tumor suppressor gene NGX6 induces changes in protein expression profiles in colon cancer HT-29 cells

Nasopharyngeal carcinoma-associated gene 6 (NGX6; syn. transmembrane protein 8B, TMEM8B) is a recently identified tumor suppressor gene. The underlying mechanisms by which the gene inhibits tumor development are not completely known. To further understand the function of the gene's protein product NGX6, in the present study, we employed two-dimensional difference gel electrophoresis to analyze the protein expression profiles of colon cancer HT-29 cells stably transfected with the gene NGX6. The differentially expressed proteins were selected and identified by matrix-assisted laser desorption/ionization coupled with time-of-flight tandem mass spectrometry. The results showed that 12 proteins were down-regulated and 4 were up-regulated in NGX6-transfected HT-29 cells, compared with vector-transfected HT-29 cells. The MS results were verified by western blot. Bioinformatic analysis showed that these proteins are involved in cell proliferation, metastasis, apoptosis, cytoskeletal structure, metabolism, and signal transduction, suggesting that NGX6 may inhibit colon cancer through the regulation of these biological processes.

Annexin A1 is associated with gastric cancer survival and promotes gastric cancer cell invasiveness through the formyl peptide receptor/extracellular signal-regulated kinase/integrin beta-1-binding protein 1 pathway

BACKGROUND

Annexin A1 (AnxA1) has been well-known as a glucocorticoid-regulated anti-inflammatory protein, and it is implicated in tumorigenesis in a tumor type-specific pattern. However, the role of AnxA1 in gastric cancer (GC) is indeterminate, and the underlying mechanism is not clear. The purpose of this study was to evaluate the prognostic significance and associated mechanism of AnxA1 in GC.

METHODS

Immunohistochemical staining was employed to analyze 118 GC patients. Both AnxA1 gain-of-function and loss-of-function approaches were performed in GC cells. Western blotting and reverse-transcription polymerase chain reaction were used for assessment of the AnxA1 regulation mechanism in GC cells. An intraperitoneal inoculation model in severe combined immunodeficient mice was used for an in vivo assay.

RESULTS

High AnxA1 expression was significantly associated with peritoneal metastasis (P = .009) and serosal invasion (P = .044). Cox multivariate analysis showed that high AnxA1 expression was an independent risk factor for poor overall survival in GC patients (P = .037). AnxA1 expression positively correlated with invasiveness of human GC cells both in vitro and in vivo. AnxA1 could regulate the GC cell invasion through the formyl peptide receptor (FPR)/extracellular signal-regulated kinase/integrin beta-1-binding protein pathway, and all 3 FPRs (FPR1 through FPR3) were involved in the regulation process.

CONCLUSIONS

High AnxA1 expression was associated with more serosal invasion, more peritoneal metastasis, and poorer overall survival in GC patients. The current study demonstrated a novel mechanism involving FPRs, extracellular signal-regulated kinases 1 and 2, and integrin beta-1-binding protein 1 by which AnxA1 regulated GC cell invasion.

Up-regulation of Annexin-A1 and lipoxin A(4) in individuals with ulcerative colitis may promote mucosal homeostasis

Background

One of the characteristics of an active episode of ulcerative colitis (UC) is the intense mucosal infiltration of leukocytes. The pro-resolution mediators Annexin-A1 (AnxA1) and lipoxin A₄ (LXA₄) exert counter-regulatory effects on leukocyte recruitment, however to date, the dual/cumulative effects of these formyl peptide receptor-2 (FPR2/ALX) agonists in the context of human intestinal diseases are unclear. To define the contribution of these mediators, we measured their expression in biopsies from individuals with UC.

Methods

Colonic mucosal biopsies were collected from two broad patient groups: healthy volunteers without (‘Ctrl’ n = 20) or with a prior history of UC (‘hx of UC’ n = 5); individuals with UC experiencing active disease (‘active’ n = 8), or in medically-induced remission (‘remission’ n = 16). We assessed the mucosal expression of LXA₄, AnxA1, and the FPR2/ALX receptor in each patient group using a combination of fluorescence microscopy, biochemical and molecular analyses.

Results

Mucosal expression of LXA₄ was elevated exclusively in biopsies from individuals in remission (3-fold, P<0.05 vs. Ctrl). Moreover, in this same group we observed an upregulation of AnxA1 protein expression (2.5-fold increase vs. Ctrl, P<.01), concurrent with an increased level of macrophage infiltration, and an elevation in FPR2/ALX mRNA (7-fold increase vs. Ctrl, P<.05). Importantly, AnxA1 expression was not limited to cells infiltrating the lamina propria but was also detected in epithelial cells lining the intestinal crypts.

Conclusions

Our results demonstrate a specific up-regulation of this pro-resolution circuit in individuals in remission from UC, and suggest a significant role for LXA₄ and AnxA1 in promoting mucosal homeostasis.

Clinical significance of expression of ANXA2 and ANXA4 in gastric adenocarcinoma

AIM: To investigate the expression of annexin A2 (ANXA2) and annexin A4 (ANXA4) in human gastric adenocarcinoma (GAC) and to explore the relationship between their expression and biological behaviors of GAC.

METHODS: The expression of ANXA2 and ANXA4 was detected by immunohistochemistry in a tissue microarray containing 75 pairs of GAC and matched tumor-adjacent tissue specimens.

RESULTS: The positive rates of ANXA2 and ANXA4 expression in GAC were significantly higher than those in tumor-adjacent tissue (33.1% vs 1.3%, 68.0% vs 25.5%, both P < 0.05). The expression of ANXA2 was positively correlated with that of ANXA4 in GAC (r = 0.335, P = 0.003). The expression of ANXA2 and ANXA4 was closely associated with invasion depth, lymph node metastasis, TNM stage and differentiation grade in GAC (all P < 0.05), but not with sex, age or distant metastasis (all P > 0.05). Tumor size had a correlation with the expression of ANXA2 (P < 0.05), but not with that of ANXA4 (P > 0.05).

CONCLUSION: Overexpression of ANXA2 and ANXA4 may play a synergistic role in the carcinogenesis, invasion and metastasis of GAC. ANXA2 and ANXA4 may be used as targets for GAC therapy and markers for prognostic prediction.

Quantitative analysis of caveolin-rich lipid raft proteins from primary and metastatic colorectal cancer clones

Caveolin-rich lipid rafts (CLRs) are thickened sections of the cell membrane that are composed of the integral membrane proteins caveolins together with saturated long chain fatty acids, cholesterol and lipids. Membrane proteins - lipid raft proteins in particular - may play important roles in cell signaling and cell-cell interaction. Due to their unique structure, CLRs seem to be the preferred docking site for specific proteins involved in focal adhesion and cancer metastasis. Our objective was thus to identify and quantify CLR proteins from primary and metastatic colorectal cancer (CRC) clones. We found differential expression of nine CLR proteins from primary and metastatic CRC clones. Among the identified proteins, an immune system inhibiting protein was significantly overexpressed in the metastatic clone, while cell adhesion and transport molecules were among the overexpressed proteins in the primary clone. All the identified CRL proteins are involved in tumorigenesis, specifically metastasis, and may thus serve as therapeutic targets. A novel concept for identification and quantification of CLR proteins with label-free mass spectrometry method was specifically examined in this study. Validation of the method against immunoblotting and FACS analysis indicates that it can be applied for the identification of novel biomarkers for cancer and metastasis.

Proteomics of a new esophageal cancer cell line established from Persian patient

Although the highest incidence of esophageal squamous cell carcinoma (ESCC) has repeatedly been reported from Persia (Iran), nevertheless the so far proteomic published reports were limited to one study on tissue specimens. Here we report the proteome of a newly established cell line from Persian ESCC patients and compare it with the normal primary cell proteome. Among polypeptides, whose expression was different in cell line sixteen polypeptides were identified by MALDI/TOF/TOF spectrometry. S100-A8 protein, annexin A1, annexin A2, regulatory subunit of calpain, subunit alpha type-3 of proteasome and glutamate dehydrogenase 1 were proteins down-regulated in cell line while peroxiredoxin-5, non-muscle myosin light polypeptide 6, keratin 1, annexin A4, keratin 8, tropomyosin 3, stress-induced-phosphoprotein 1 and albumin were found to be subject of up-regulation in cell line compared to the primary normal cells. The proteomic results were further verified by western blotting and RT-PCR on annexin A1 and keratin 8. In addition, among the aforementioned proteins, glutamate dehydrogenase 1, regulatory subunit of calpain, subunit alpha of type-3 proteasome and annexin A4 are proteins whose deregulation in ESCC is reported for the first time by this study.

Kaposi's sarcoma-associated herpesvirus latency-associated nuclear antigen and angiogenin interact with common host proteins, including annexin A2, which is essential for survival of latently infected cells

Kaposi's sarcoma-associated herpesvirus (KSHV) infection and latency-associated nuclear antigen (LANA-1) upregulate the multifunctional protein angiogenin (ANG). Our studies demonstrate that silencing ANG or inhibiting its nuclear translocation downregulates KSHV LANA-1 expression and ANG is necessary for KSHV latency, anti-apoptosis and angiogenesis (Sadagopan et al., J. Virol. 83:3342-3364, 2009; Sadagopan et al., J Virol. 85:2666-2685, 2011). Here we show that LANA-1 interacts with ANG and colocalizes in latently infected endothelial telomerase-immortalized human umbilical vein endothelial (TIVE-LTC) cells. Mass spectrometric analyses of TIVE-LTC proteins immunoprecipitated by anti-LANA-1 and ANG antibodies identified 28 common cellular proteins such as ribosomal proteins, structural proteins, tRNA synthetases, metabolic pathway enzymes, chaperons, transcription factors, antioxidants, and ubiquitin proteosome proteins. LANA-1 and ANG interaction with one of the proteins, annexin A2, was validated. Annexin A2 has been shown to play roles in cell proliferation, apoptosis, plasmin generation, exocytosis, endocytosis, and cytoskeleton reorganization. It is also known to associate with glycolytic enzyme 3-phosphoglyceratekinase in the primer recognition protein (PRP) complex that interacts with DNA polymerase α in the lagging strand of DNA during replication. A higher level of annexin A2 is expressed in KSHV+ but not in Epstein-Barr virus (EBV)+ B-lymphoma cell lines. Annexin A2 colocalized with several LANA-1 punctate spots in KSHV+ body cavity B-cell lymphoma (BCBL-1) cells. In triple-staining analyses, we observed annexin A2-ANG-LANA-1, annexin A2-ANG, and ANG-LANA-1 colocalizations. Annexin A2 appeared as punctate nuclear dots in LANA-1-positive TIVE-LTC cells. In LANA-1-negative TIVE-LTC cells, annexin A2 was detected predominately in the cytoplasm, with some nuclear spots, and colocalization with ANG was observed mostly in the cytoplasm. Annexin A2 coimmunoprecipitated with LANA-1 and ANG in TIVE-LTC and BCBL-1 cells and with ANG in 293T cells independent of LANA-1. This suggested that annexin A2 forms a complex with LANA-1 and ANG as well as a separate complex with ANG. Silencing annexin A2 in BCBL-1 cells resulted in significant cell death, downregulation of cell cycle-associated Cdk6 and of cyclin D, E, and A proteins, and downregulation of LANA-1 and ANG expression. No effect was seen in KSHV⁻ lymphoma (BJAB and Ramos) and 293T cells. These studies suggest that LANA-1 association with annexin A2/ANG could be more important than ANG association with annexin A2, and KSHV probably uses annexin A2 to maintain the viability and cell cycle regulation of latently infected cells. Since the identified LANA-1- and ANG-interacting common cellular proteins are hitherto unknown to KSHV and ANG biology, this offers a starting point for further analysis of their roles in KSHV biology, which may lead to identification of potential therapeutic targets to control KSHV latency and associated malignancies.

The proteomics of colorectal cancer: identification of a protein signature associated with prognosis

Colorectal cancer is one of the commonest types of cancer and there is requirement for the identification of prognostic biomarkers. In this study protein expression profiles have been established for colorectal cancer and normal colonic mucosa by proteomics using a combination of two dimensional gel electrophoresis with fresh frozen sections of paired Dukes B colorectal cancer and normal colorectal mucosa (n = 28), gel image analysis and high performance liquid chromatography–tandem mass spectrometry. Hierarchical cluster analysis and principal components analysis showed that the protein expression profiles of colorectal cancer and normal colonic mucosa clustered into distinct patterns of protein expression. Forty-five proteins were identified as showing at least 1.5 times increased expression in colorectal cancer and the identity of these proteins was confirmed by liquid chromatography–tandem mass spectrometry. Fifteen proteins that showed increased expression were validated by immunohistochemistry using a well characterised colorectal cancer tissue microarray containing 515 primary colorectal cancer, 224 lymph node metastasis and 50 normal colonic mucosal samples. The proteins that showed the greatest degree of overexpression in primary colorectal cancer compared with normal colonic mucosa were heat shock protein 60 (p<0.001), S100A9 (p<0.001) and translationally controlled tumour protein (p<0.001). Analysis of proteins individually identified 14-3-3β as a prognostic biomarker (χ² = 6.218, p = 0.013, HR = 0.639, 95%CI 0.448–0.913). Hierarchical cluster analysis identified distinct phenotypes associated with survival and a two-protein signature consisting of 14-3-3β and aldehyde dehydrogenase 1 was identified as showing prognostic significance (χ² = 7.306, p = 0.007, HR = 0.504, 95%CI 0.303–0.838) and that remained independently prognostic (p = 0.01, HR = 0.416, 95%CI 0.208–0.829) in a multivariate model.

Analysis and prediction of cancerlectins using evolutionary and domain information

BACKGROUND

Predicting the function of a protein is one of the major challenges in the post-genomic era where a large number of protein sequences of unknown function are accumulating rapidly. Lectins are the proteins that specifically recognize and bind to carbohydrate moieties present on either proteins or lipids. Cancerlectins are those lectins that play various important roles in tumor cell differentiation and metastasis. Although the two types of proteins are linked, still there is no computational method available that can distinguish cancerlectins from the large pool of non-cancerlectins. Hence, it is imperative to develop a method that can distinguish between cancer and non-cancerlectins.

RESULTS

All the models developed in this study are based on a non-redundant dataset containing 178 cancerlectins and 226 non-cancerlectins in which no two sequences have more than 50% sequence similarity. We have applied the similarity search based technique, i.e. BLAST, and achieved a maximum accuracy of 43.25%. The amino acids compositional analysis have shown that certain residues (e.g. Leucine, Proline) were preferred in cancerlectins whereas some other (e.g. Asparatic acid, Asparagine) were preferred in non-cancerlectins. It has been found that the PROSITE domain "Crystalline beta gamma" was abundant in cancerlectins whereas domains like "SUEL-type lectin domain" were found mainly in non-cancerlectins. An SVM-based model has been developed to differentiate between the cancer and non-cancerlectins which achieved a maximum Matthew's correlation coefficient (MCC) value of 0.32 with an accuracy of 64.84%, using amino acid compositions. We have developed a model based on dipeptide compositions which achieved an MCC value of 0.30 with an accuracy of 64.84%. Thereafter, we have developed models based on split compositions (2 and 4 parts) and achieved an MCC value of 0.31, 0.32 with accuracies of 65.10% and 66.09%, respectively. An SVM model based on Position Specific Scoring Matrix (PSSM), generated by PSI-BLAST, was developed and achieved an MCC value of 0.36 with an accuracy of 68.34%. Finally, we have integrated the PROSITE domain information with PSSM and developed an SVM model that has achieved an MCC value of 0.38 with 69.09% accuracy.

CONCLUSION

BLAST has been found inefficient to distinguish between cancer and non-cancerlectins. We analyzed the protein sequences of cancer and non-cancerlectins and identified interesting patterns. We have been able to identify PROSITE domains that are preferred in cancer and non-cancerlectins and thus provided interesting insights into the two types of proteins. The method developed in this study will be useful for researchers studying cancerlectins, lectins and cancer biology. The web-server based on the above study, is available at http://www.imtech.res.in/raghava/cancer_pred/

Advances in understanding the relationship between annexin A1 and gastrointestinal cancer

Annexin A1 is a member of the annexin family of calcium-dependent phospholipid-binding proteins and participates in many important life processes, such as cellular signal transduction, proliferation, differentiation and apoptosis. Recent studies have shown that the expression levels of annexin A1 vary among different tumor tissues and different tumor subtypes and may be associated with the development, invasion and metastasis of malignant tumors. Understanding the relationship between annexin A1 and tumors has important implications for the early diagnosis and treatment of tumors.

Analysis of the human pancreatic stellate cell secreted proteome

OBJECTIVE

Pancreatic stellate cells (PSCs) are important players in pancreatic fibrosis and are major contributors to the extracellular matrix proteins observed with the stromal response characteristic of pancreatic ductal adenocarcinoma (PDAC). Pancreatic stellate cells are also believed to secrete soluble factors that promote tumor progression; however, no comprehensive analysis of the PSC proteome in either the quiescent or the activated state has been reported.

METHODS

Using 2-dimensional tandem mass spectrometry and the RLT-PSC cell line, we present the first comprehensive study describing and comparing the quiescent and activated human PSC-secreted proteomes.

RESULTS

Very few proteins are secreted in the quiescent state. In stark contrast, activated PSCs secreted a vast array of proteins. Many of these proteins differed from those secreted by PDAC-derived cell lines. Proteins associated with wound healing, proliferation, apoptosis, fibrosis, and invasion were characterized. Selected proteins were verified in human tissue samples from PDAC, dysplastic pancreas, and normal pancreas using Western blot analysis and immunohistochemical staining.

CONCLUSIONS

Our study represents the first comprehensive analysis of proteins secreted by PSCs. These findings lay the foundation for characterizing PSC-derived proteins involved in stroma-tumor interactions and the promotion of pancreatitis and PDAC.

Impact of obesity and leptin on protein expression profiles in mouse colon

BACKGROUND

Elevated leptin levels in obesity are associated with increased risk of colon pathology, implicating leptin signaling in colon disease. However, leptin-regulated processes in the colon are currently uncharacterized. Previously, we demonstrated that leptin receptors are expressed on colon epithelium and that increased adiposity and elevated plasma leptin in rats are associated with perturbed metabolism in colon tissue. Thus, we hypothesize that obesity disrupts expression of proteins regulated by leptin in the colon.

METHODS

A proteomic analysis was conducted to investigate firstly, differences in the colon of mice lacking leptin and leptin signaling (ob/ob and db/db, respectively) by comparing protein expression profiles with wild-type mice. Secondly, responses to leptin challenge in wild-type mice and ob/ob mice were compared to identify leptin-regulated proteins and associated cellular processes.

RESULTS

Forty proteins were identified with significantly altered expression patterns associated with differences in leptin status in comparisons between all groups of mice. These proteins are associated with calcium binding, cell cycle, cell proliferation, electron transport chain, energy metabolism, protein folding and transport, redox regulation, structural proteins, and proteins involved in transport and regulation of mucus production.

CONCLUSIONS

This study provides evidence that obesity and leptin significantly alter protein profiles of a number of proteins linked to cellular processes in colon tissues that may be linked to the increased risk of colon pathology associated with obesity.

Increased expression of annexin A1 is correlated with K-ras mutation in colorectal cancer

The activation of K-ras gene and expression of annexin A1 play an important role in colorectal tumorigenesis. We initiated this study to analyze the possible relationship between the annexin A1 expression and the K-ras mutation status in colorectal cancer. K-ras mutations are present in one fourth to one half of colorectal cancers. Annexin A1, a 37-kDa calcium- and phospholipid-binding protein, is over-expressed in colorectal cancers and may be involved in invasive tumor growth and metastasis. Here, we examined twenty paired specimens of colorectal cancer and adjacent normal tissues for K-ras mutations and annexin A1 expression. Sequencing analysis of codons 12 and 13 of K-ras revealed the presence of K-ras mutations in six colorectal cancer tissue specimens (30%). RT-PCR and immunoblotting studies further found that the expression levels of annexin A1 mRNA and protein were increased (2.9-fold and 1.7-fold, respectively) in colorectal cancers harboring K-ras codon 12 or codon 13 mutation compared with adjacent normal tissues (P < 0.05). In colorectal cancer tissues with wild-type K-ras, 12 (85.7%) specimens showed reduced expression of annexin A1 (0.48-fold and 0.81-fold, respectively). No significant association was found between K-ras mutations or annexin A1 over-expression and demographic or other clinicopathological parameters such as gender, differentiation or metastasis. However, a significant and positive correlation was identified between K-ras mutations and annexin A1 over-expression. Our findings indicate that annexin A1 could be implicated in colorectal cancer development and progression and could be of potential use as a predictive marker for guiding targeted therapy for colorectal cancer.

Global expression study in colorectal cancer on proteins with alkaline isoelectric point by two-dimensional difference gel electrophoresis

Colorectal cancer is one of the leading causes of cancer death worldwide. To identify candidates for biomarkers and therapeutic targets, we investigated the proteome of colorectal cancer tissues. Using 2D-DIGE in combination with our original large format electrophoresis apparatus, we compared surgically resected normal and tumor tissues from 53 patients with colorectal cancer. We focused on proteins with an alkaline pI using IPG gels for the alkaline range. We observed 1687 protein spots, and found 100 spots with statistical (p<0.01) and significant (>2-fold) differences between the normal and the tumor tissue groups. Among these 100 protein spots, five showed a different intensity between tumor tissues from the stage-II and the stage-III patients. MS experiments revealed that these 100 protein spots corresponded to 58 unique proteins. These included six proteins which had not been previously reported to be associated with colorectal cancer. Among these proteins, five were not reported in any type of malignancy. IEF/western blotting confirmed the differences in protein expression between the normal and the tumor tissues. These results may provide an insight for biomarker development and drug target discovery in colorectal cancer.

The role of annexin A2 in tumorigenesis and cancer progression

Annexin A2 is a calcium-dependent, phospholipid-binding protein found on various cell types. It is up-regulated in various tumor types and plays multiple roles in regulating cellular functions, including angiogenesis, proliferation, apoptosis, cell migration, invasion and adhesion. Annexin A2 binds with plasminogen and tissue plasminogen activator on the cell surface, which leads to the conversion of plasminogen to plasmin. Plasmin is a serine protease which plays a key role in the activation of metalloproteinases and degradation of extracellular matrix components essential for metastatic progression. We have recently found that both annexin A2 and plasmin are increased in conditioned media of co cultured ovarian cancer and peritoneal cells. Our studies suggest that annexin A2 is part of a tumor-host signal pathway between ovarian cancer and peritoneal cells which promotes ovarian cancer metastasis. Accumulating evidence suggest that interactions between annexin A2 and its binding proteins play an important role in the tumor microenvironment and act together to enhance cancer metastasis. This article reviews the current knowledge on the biological role of annexin A2 and its binding proteins in solid malignancies including ovarian cancer.

Custom design of a GeXP multiplexed assay used to assess expression profiles of inflammatory gene targets in normal colon, polyp, and tumor tissue

Colon cancers are characterized by aberrant gene expression signatures associated with disease initiation and progression. Identification of aberrant gene expression associated with colon carcinogenesis has increased significantly with application of gene array technologies. Downstream processing of these data has been hindered by the lack of robust multiplexed gene quantitative technologies facilitating study of the identified multiple gene targets. The GenomeLab Genetic Analysis System presents a novel technology platform for quantitative multiplexed gene expression analysis. This report describes the custom design of a GeXP multiplexed assay used to assess expression profiles of 14 inflammatory gene targets in normal, polyp, and tumor tissue. Characteristic normal, polyp, and tumor tissue gene expression profiles were obtained. Statistical analysis confirmed comparable relative quantitation of gene expression using the GeXP, macroarray, and single-plex real-time polymerase chain reaction assays. GeXP assays may be usefully applied in clinical and regulatory studies of multiple gene targets. This system permits custom-design options for relative quantification of multiple gene target expression, simultaneously in a single reaction, using nanogram quantities of total RNA template. The system provides an approach to advance the study of multiple targets identified from gene array analysis with potential for characterizing gene expression signatures in clinical diagnostics.

The use of formalin fixed wax embedded tissue for proteomic analysis: Table 1

The potential of proteomic approaches to elucidate disease pathogenesis and biomarker discovery is increasingly being recognised. These studies are usually based on the use of fresh tissue samples. Problems in obtaining and storing fresh frozen samples, especially either for the investigation of rare diseases or for the study of microscopic disease foci, have led to the investigation of the possible use of formalin fixed wax embedded tissue for proteomic biomarker detection Overcoming problems with protein cross-linking associated with formalin fixation of tissues, especially by using heat-mediated retrieval techniques combined with highly sensitive methods for protein separation and identification are now emerging, giving promise to the use of formalin fixed wax embedded tissues for proteomic analysis. Formalin fixed wax embedded tissues, together with their associated clinical and pathological information outcome may provide significant potential opportunities for proteomics research. Such studies of formalin fixed wax embedded tissue will allow access to already acquired clinical tissue samples which can be readily correlated with clinical, pathological and outcome data. It also provides access to rare types of tissue/diseases that would be either difficult to collect prospectively in a timely manner or are unlikely to be available as fresh samples. The purpose of this review is to provide an overview of the issues associated with the use of formalin fixed wax embedded tissues for proteomics.

The role of lysyl oxidase in SRC-dependent proliferation and metastasis of colorectal cancer

BACKGROUND

Emerging evidence implicates lysyl oxidase (LOX), an extracellular matrix-modifying enzyme, in promoting metastasis of solid tumors. We investigated whether LOX plays an important role in the metastasis of colorectal cancer (CRC).

METHODS

We analyzed LOX expression in a patient CRC tissue microarray consisting of normal colon mucosa (n = 49), primary (n = 510), and metastatic (n = 198) tissues. LOX was overexpressed in CRC cell line SW480 (SW480+LOX), and the expression was knocked down in CRC cell line SW620 using LOX-specific short hairpin RNA (SW620+shLOX). Effect of LOX manipulation on three-dimensional cell proliferation and invasion was characterized in vitro. Effect of LOX manipulation on tumor proliferation and metastasis was investigated in a subcutaneous tumor mouse model (n = 3 mice per group) and in an intrasplenic metastatic mouse model (n = 3 mice per group). The mechanism of LOX-mediated effects via v-src sarcoma (Schmidt-Ruppin A-2) viral oncogene homolog (avian) (SRC) was investigated using dasatinib, an inhibitor of SRC activation. All statistical tests were two-sided.

RESULTS

Compared with normal colon tissue (n = 49), LOX expression was statistically significantly increased in tumor tissues (n = 510) of CRC patients (P < .001), and a greater increase was observed in metastatic tissue (n = 198). SW480+LOX cells showed a statistically significantly increased three-dimensional proliferation (P = .037) and invasion (P = .015), whereas SW620+shLOX cells showed reduced proliferation (P = .011) and invasion (P = .013) compared with controls. Subcutaneous tumor growth in mice was statistically significantly increased in SW480+LOX tumors (P = .036) and decreased in SW620+shLOX tumors (P = .048), and metastasis was statistically significantly increased in SW480+LOX tumors (P = .044) and decreased in SW620+shLOX tumors (SW620 control vs SW620+shLOX, mean = 1.0 luminescent signal, 95% confidence interval = 0.3 to 1.7 luminescent signal, vs mean = 0.3 luminescent signal, 95% confidence interval = 0.1 to 0.5 luminescent signal; P = .035) compared with controls. LOX-mediated effects on tumor progression were associated with SRC activation, and these effects were inhibited by dasatinib.

CONCLUSIONS

LOX showed an important role in CRC cell proliferation and metastasis and was dependent on the activation of SRC. These results have the potential to identify patients with high SRC activity, who may benefit from dasatinib treatment.

Up-regulated Annexin A1 expression in gastrointestinal cancer is associated with cancer invasion and lymph node metastasis

Annexin A1 (ANXA1) is a calcium-dependent phospholipid-linked protein, involved in anti-inflammatory effects, regulation of cellular differentiation, proliferation and apoptosis. In the present study, we investigated the expression of ANXA1 in gastric and colon cancer, and analyzed the relationship between ANXA1 expression and clinicopathological factors. ANXA1 mRNA expression in gastric and colon cancer tissues was not significantly changed compared to that in normal tissues. When ANXA1 protein expression was evaluated by immunohistochemical staining, ANXA1 expression was observed in 76 of 135 cases of gastric cancer (56.3%), and correlations were found between ANXA1 expression and depth of wall invasion (P<0.001), lymphatic invasion (P=0.023), venous invasion (P=0.002), lymph node metastasis (P=0.001) and UICC stage (P<0.001). Disease-specific survival rate was significantly lower in cases with ANXA1 expression compared to that in cases without (P=0.0053). In colon cancer, ANXA1 expression was detected in 61 of 210 cases (29.0%) and correlations were found with gender (P=0.038), lymphatic invasion (P=0.011), venous invasion (P=0.023), lymph node metastasis (P=0.042) and UICC stage (P=0.041). The disease-specific survival rate tended to be lower in cases with ANXA1 expression, although the differences were not statistically significant (P=0.6984). Our results indicate that up-regulated ANXA1 expression is involved in cancer invasion and lymph node metastasis. Furthermore, high levels of ANXA1 expression were implicated in poor prognosis of patients. ANXA1 may be applicable as a prognostic biomarker in gastric and colon cancer, and a potential target for treatment.