A comparative study of two PODXL antibodies in 840 colorectal cancer patients

Radiation-Induced Overexpression of TGFβ and PODXL Contributes to Colorectal Cancer Cell Radioresistance through Enhanced Motility

The primary cause of colorectal cancer (CRC) recurrence is increased distant metastasis after radiotherapy, so there is a need for targeted therapeutic approaches to reduce the metastatic-relapse risk. Dysregulation of the cell-surface glycoprotein podocalyxin-like protein (PODXL) plays an important role in promoting cancer-cell motility and is associated with poor prognoses for many malignancy types. We found that CRC cells exposed to radiation demonstrated increased TGFβ and PODXL expressions, resulting in increased migration and invasiveness due to increased extracellular matrix deposition. In addition, both TGFβ and PODXL were highly expressed in tissue samples from radiotherapy-treated CRC patients compared to those from patients without this treatment. However, it is unclear whether TGFβ and PODXL interactions are involved in cancer-progression resistance after radiation exposure in CRC. Here, using CRC cells, we showed that silencing PODXL blocked radiation-induced cell migration and invasiveness. Cell treatment with galunisertib (a TGFβ-pathway inhibitor) also led to reduced viability and migration, suggesting that its clinical use may enhance the cytotoxic effects of radiation and lead to the effective inhibition of CRC progression. Overall, the results demonstrate that downregulation of TGFβ and its-mediated PODXL may provide potential therapeutic targets for patients with radiotherapy-resistant CRC.

PODXL might be a new prognostic biomarker in various cancers: a meta-analysis and sequential verification with TCGA datasets

ABSRACT

BACKGROUND: Several studies have investigated the associations between the podocalyxin-like protein (PODXL) expression quantity or locations and cancers survival, but the results were far from conclusive. Therefore, we proceeded a meta-analysis on PODXL in various human cancers to find its prognostic value and followed confirmation using the TCGA datasets.

METHODS

We performed a systematic search, and 18 citations, including 5705 patients were pooled in meta-analysis. The results were verified with TCGA datasets.

RESULTS

Total eligible studies comprised 5705 patients with 10 types of cancer. And the result indicated that PODXL high-expression or membrane-expression were significantly related to poor overall survival (OS). However, subgroup analysis showed a significant association between high expressed PODXL and poor OS in the colorectal cancer, pancreatic cancer, urothelial bladder cancer, renal cell carcinoma and glioblastoma multiforme. Then, we validated the inference using TCGA datasets, and the consistent results were demonstrated in patients with pancreatic cancer, glioblastoma multiforme, gastric cancer, esophageal cancer and lung adenocarcinoma.

CONCLUSION

The result of meta-analysis showed that high expressed PODXL was significantly linked with poor OS in pancreatic cancer and glioblastoma multiforme, but not in gastric cancer, esophageal cancer or lung adenocarcinoma. And the membrane expression of PODXL might also associate with poor OS. PODXL may act as tumor promotor and may serve as a potential target for antitumor therapy.

Surface markers of human embryonic stem cells: a meta analysis of membrane proteomics reports

INTRODUCTION

Human embryonic stem cells (hESCs) have unique biological features and attributes that make them attractive in various areas of biomedical research. With heightened applications, there is an ever increasing need for advancement of proteome analysis. Membrane proteins are one of the most important subset of hESC proteins as they can be used as surface markers. Areas covered: This review discusses commonly used surface markers of hESCs, and provides in-depth analysis of available hESC membrane proteome reports and the existence of these markers in many other cell types, especially cancer cells. Appreciating, existing ambiguity in the definition of a membrane protein, we have attempted a meta analysis of the published membrane protein reports of hESCs by using a combination of protein databases and prediction tools to find the most confident plasma membrane proteins in hESCs. Furthermore, responsiveness of plasma membrane proteins to differentiation has been discussed based on available transcriptome profiling data bank. Expert commentary: Combined transcriptome and membrane proteome analysis highlighted additional proteins that may eventually find utility as new cell surface markers.

Podocalyxin-like protein as a predictive biomarker for benefit of neoadjuvant chemotherapy in resectable gastric and esophageal adenocarcinoma

BACKGROUND

We have previously shown that podocalyxin-like protein (PODXL) is a prognostic biomarker for poor survival in gastric and esophageal adenocarcinoma treated with surgery up-front. The aim of the present study was to assess PODXL expression in tumors from patients treated with neoadjuvant ± adjuvant (i.e. preoperative with or without postoperative) chemotherapy, with regard to histopathologic response, time to recurrence (TTR) and overall survival (OS).

METHODS

The neoadjuvant cohort encompasses 148 consecutive patients who received neoadjuvant ± adjuvant chemotherapy for resectable gastric or esophageal adenocarcinoma between 2008 and 2014. Immunohistochemical expression of PODXL was assessed in pre-neoadjuvant biopsies, resected primary tumors and lymph node metastases. Histopathologic response was evaluated using the Chirieac grading. TTR and OS were estimated using Kaplan-Meier and Cox regression analyses. To investigate a potential predictive role for PODXL, the neoadjuvant cohort was pooled with the previously reported surgery up-front cohort.

RESULTS

The majority (> 95%) of the patients were treated with fluoropyrimidine- and oxaliplatin-based chemotherapy. Patients with high PODXL expression in their pre-neoadjuvant biopsies had a superior histopathologic response (notably 36% with no residual cancer cells) compared to those with negative or low PODXL expression, and were all recurrence-free at last follow-up. In the pooled cohort, no benefit of chemotherapy could be shown for PODXL negative cases, whereas PODXL positive (low or high) cases had a prolonged TTR and OS when treated with neoadjuvant ± adjuvant chemotherapy compared to surgery alone. The potential predictive role of PODXL was further strengthened for TTR in Cox regression analyses, especially for patients treated with neoadjuvant fluoropyrimidine and oxaliplatin for a minimum of 8 weeks, with a significant interaction term in both unadjusted (p = 0.006) and adjusted (p = 0.024) analyses. The interaction term was not statistically significant for overall survival.

CONCLUSIONS

Patients with resectable gastric or esophageal adenocarcinoma with high PODXL expression in their diagnostic biopsies have an excellent prognosis when treated with neoadjuvant ± adjuvant fluoropyrimidine- and oxaliplatin-based chemotherapy. If the suggested predictive role of PODXL for benefit of chemotherapy can be confirmed, patients with PODXL negative tumors could be spared chemotherapy and treated with surgery alone.

Immunohistochemical Analysis Using Antipodocalyxin Monoclonal Antibody PcMab-47 Demonstrates Podocalyxin Expression in Oral Squamous Cell Carcinomas

Podocalyxin is a CD34-related type I transmembrane protein that is highly glycosylated with N-glycan, O-glycan, and keratan sulfate. Podocalyxin was originally found in the podocytes of rat kidney and is reportedly expressed in many types of tumors, including brain tumors, colorectal cancers, and breast cancers. Overexpression of podocalyxin is an independent predictor of progression, metastasis, and poor outcome. We recently immunized mice with recombinant human podocalyxin, which was produced using LN229 glioblastoma cells, and produced a novel antipodocalyxin monoclonal antibody (mAb), PcMab-47, which reacts with endogenous podocalyxin-expressing cancer cell lines and normal cell lines independent of glycosylation in Western blot, flow cytometry, and immunohistochemical analyses. In this study, we performed immunohistochemical analysis against oral cancers using PcMab-47. PcMab-47-stained oral squamous cell carcinoma cells in a cytoplasmic pattern and detected 26/38 (68.4%) of oral squamous cell carcinoma cells on tissue microarrays. These results indicate that PcMab-47 is useful in detecting podocalyxin of oral cancers for immunohistochemical analysis.

Antipodocalyxin Antibody chPcMab-47 Exerts Antitumor Activity in Mouse Xenograft Models of Colorectal Adenocarcinomas

Podocalyxin (PODXL) is expressed in several cancers, including brain tumors and colorectal cancers. PODXL overexpression is an independent predictor of progression, metastasis, and poor outcome. We recently immunized mice with recombinant human PODXL, which was produced using LN229 glioblastoma cells, and produced a clone PcMab-47 that could be used for investigating PODXL expression by flow cytometry and immunohistochemical analysis. Herein, we produced a human-mouse chimeric PcMab-47 (chPcMab-47) and investigated its antitumor activity against PODXL-expressing tumors. chPcMab-47 reacted with LN229, LN229/PODXL, and Chinese hamster ovary (CHO)/PODXL cells, but it did not react with CHO-K1 or PODXL-knockout LN229 cell line (PDIS-13). chPcMab-47 exerted antitumor activity against a mouse xenograft model using CHO/PODXL. Furthermore, chPcMab-47 was reactive with colorectal cancer cell lines such as HCT-15, Caco-2, HCT-8, and DLD-1. chPcMab-47 also exhibited antitumor activity against a mouse xenograft model using HCT-15. These results suggest that chPcMab-47 could be useful for antibody therapy against PODXL-expressing cancers.

PcMab-47: Novel Antihuman Podocalyxin Monoclonal Antibody for Immunohistochemistry

Podocalyxin (PODXL) is a CD34-related sialomucin and a well-known marker of embryonic stem cells. PODXL is expressed in many types of tumors including colorectal cancers, breast cancers, and brain tumors. Overexpression of PODXL is an independent predictor of progression, metastasis, and poor outcome. PODXL is also expressed in many normal cells such as renal podocytes and endothelial cells (ECs). However, high-sensitive and high-specific anti-PODXL monoclonal antibodies (mAbs) have not been established. Herein, we immunized mice with recombinant human PODXL, which was produced using LN229 glioblastoma cells. The anti-PODXL mAb, PcMab-47, reacted with endogenous PODXL-expressing cancer cell lines and normal cells independently of glycosylation in flow cytometry. Immunohistochemical analysis showed that PcMab-47 detected PODXL-expressing normal cells such as podocytes of kidney or ECs. Furthermore, PcMab-47 stained PODXL-expressing cancer cells of colon or breast cancers. These results suggest that PcMab-47 could be useful for investigating the expression and function of PODXL in cancers and normal tissues.

Expression of podocalyxin-like protein is an independent prognostic biomarker in resected esophageal and gastric adenocarcinoma

BACKGROUND

Podocalyxin-like protein (PODXL) is a cell surface transmembrane glycoprotein, the expression of which has been associated with poor prognosis in a range of malignancies. The aim of this study was to investigate the impact of PODXL expression on survival in esophageal and gastric adenocarcinoma.

METHODS

The study cohort consists of a consecutive series of 174 patients with esophageal (including the gastroesophageal junction) or gastric adenocarcinoma, surgically treated between 2006 and 2010 and not subjected to neoadjuvant treatment. Immunohistochemical expression of PODXL was assessed in tissue microarrays with cores from primary tumors, lymph node metastases, intestinal metaplasia and adjacent normal epithelium. Survival analyses were performed on patients with no distant metastases and no macroscopic residual tumor.

RESULTS

In the majority of cases, expression of PODXL was significantly higher in cancer cells compared to normal epithelial cells and was significantly associated with lymph node metastases and high grade tumors. In esophageal adenocarcinoma, Kaplan-Meier analyses revealed that patients with PODXL negative tumors had a superior time to recurrence (TTR) and overall survival (OS) compared to patients with PODXL positive tumors. In gastric adenocarcinoma, patients with PODXL negative tumors had a superior TTR and a trend towards an improved OS. In esophageal and gastric adenocarcinoma combined, the prognostic significance of PODXL expression on TTR was confirmed in unadjusted Cox regression analysis (HR = 5.36, 95 % CI 1.68-17.06, p = 0.005) and remained significant in the adjusted model (HR = 3.39, 95 % CI 1.01-11.35, p = 0.048). Moreover, the impact of PODXL expression on OS was also confirmed in unadjusted analysis (HR = 2.52, 95 % CI 1.31-4.85, p = 0.006) and remained significant in the adjusted model (HR = 2.03, 95 % CI 1.04-3.98, p = 0.039).

CONCLUSIONS

In esophageal and gastric adenocarcinoma, PODXL expression is an independent prognostic biomarker for reduced time to recurrence and poor overall survival. This is the first report on the prognostic role of PODXL in esophageal adenocarcinoma and validates recent findings in gastric cancer.

Podocalyxin as a Prognostic Marker in Gastric Cancer

Background

Podocalyxin-like 1 (PODXL) is a cell-adhesion glycoprotein associated with aggressive tumor phenotype and poor prognosis in several forms of cancer. The aim of this study was to investigate PODXL expression in gastric cancer by use of two different antibodies.

Methods

By tumor-tissue microarrays and immunohistochemistry we evaluated PODXL expression in tumor specimens from 337 patients who underwent surgery for gastric adenocarcinoma at Helsinki University Hospital. We used two different antibodies: HPA2110, which is a polyclonal antibody and an in-house monoclonal antibody called HES9, to investigate the association of PODXL expression with clinicopathologic variables and patient survival.

Results

PODXL staining was positive by the polyclonal antibody in 153 (57.5%) cases and by the monoclonal antibody in 212 (76%). Polyclonal antibody expression was associated with intestinal cancer type (p<0.001). Monoclonal antibody staining was associated with age over 66 (p = 0.001), with intestinal cancer (p<0.001), and with small tumor size (≤ 5 cm; p = 0.024). Both antibodies were associated with high S-phase fraction (p = 0.022; p = 0.010), and high tumor proliferation index (Ki-67; p = 0.003; p = 0.001). PODXL positivity by the polyclonal antibody indicated reduced gastric-cancer-specific 5-year survival of 24.0% (95% CI 16.9–31.1), compared to 43.3% (95% CI 33.7–52.9) for patients with PODXL negativity (p = 0.001). The result remained significant in multivariable analysis (HR = 3.17; 95% CI 1.37–7.34, p = 0.007).

Conclusion

In gastric cancer, PODXL expression by the polyclonal antibody HPA2110 is an independent marker of poor prognosis.

The epithelial-mesenchymal transition in cancer: a potential critical topic for translational proteomic research

The epithelial-mesenchymal transition (EMT) is a morphogenetic process that results in a loss of epithelial characteristics and the acquisition of a mesenchymal phenotype. First described in embryogenesis, the EMT has been recently implicated in carcinogenesis and tumor progression. In addition, recent evidence has shown that stem-like cancer cells present the hallmarks of the EMT. Some of the molecular mechanisms related to the interrelationships between cancer pathophysiology and the EMT are well-defined. Nevertheless, the precise molecular mechanism by which epithelial cancer cells acquire the mesenchymal phenotype remains largely unknown. This review focuses on various proteomic strategies with the goal of better understanding the physiological and pathological mechanisms of the EMT process.

Podocalyxin Is a Marker of Poor Prognosis in Pancreatic Ductal Adenocarcinoma

Aim of the Study

Podocalyxin-like 1 is a transmembrane glyco-protein whose overexpression associates in many cancers with poor prognosis and unfavorable clinicopathological characteristics. Until now, its prognostic value has never been studied in pancreatic ductal adenocarcinoma (PDAC). The aim of this study was to investigate podocalyxin expression in PDAC by a novel monoclonal antibody and a commercially available polyclonal antibody.

Patients and Materials

With tissue microarrays and immuno-histochemistry, podocalyxin expression evaluation involved 168 PDAC patients. The associa-tions of the podocalyxin tumor expression with clinicopathological variables were explored by Fisher’s exact test and the linear-by-linear test. Survival analyses were by Kaplan-Meier anal-ysis and the Cox proportional hazard model.

Results

The polyclonal antibody revealed membranous podocalyxin expression in 73 (44.0%) specimens and the monoclonal antibody was highly expressed in 36 (21.8%) cases. Membranous expression by the polyclonal antibody was associated with T classification (p=0.045) and perineural invasion (p=0.005), and high expression by the mono-clonal antibody with poor differentiation (p=0.033). High podocalyxin expression associated significantly with higher risk of death from PDAC by both the polyclonal antibody (hazard ratio (HR) = 1.62; 95% confidence interval (CI) 1.12-2.33; p=0.01) and the monoclonal antibody (HR = 2.10, 95% CI 1.38-3.20; p<0.001). The results remained significant in multivariate analysis, adjusted for age, gender, stage, lymph node ratio (≥/< 20%), and perivascular invasion (respectively as HR = 2.03; 95% CI 1.32-3.13, p=0.001; and as HR = 2.36; 95% CI 1.47-3.80, p<0.001).

Conclusion

We found podocalyxin to be an independent factor for poor prognosis in PDAC. To our knowledge, this is the first such report of its prognostic value.

Prognostic and predictive significance of podocalyxin-like protein expression in pancreatic and periampullary adenocarcinoma

Background

Adenocarcinoma of the periampullary region is associated with poor prognosis and new prognostic and treatment predictive biomarkers are needed for improved treatment. Membranous expression of podocalyxin-like 1(PODXL), which is a cell-adhesion glycoprotein and stem cell marker, has been found to correlate with an aggressive tumour phenotype and adverse outcome in several cancer types. The aim of the present study was to examine the clinicopathological correlates, prognostic and predictive significance of tumour-specific PODXL expression in a retrospective cohort of pancreatic and periampullary carcinoma, morphologically divided into intestinal type (I-type) and pancreatobiliary type (PB-type) tumours.

Methods

Immunohistochemical expression of PODXL was analysed in tissue microarrays with primary tumours and a subset of paired lymph node metastases from 175 patients operated with pancreaticoduodenectomy for periampullary adenocarcinoma. Chi square test was applied to analyse the relationship between PODXL expression and clinicopathological parameters. Kaplan Meier analysis and Cox regression models were applied to estimate differences in 5-year overall survival (OS) and recurrence-free survival (RFS) in strata according to membranous and non-membranous PODXL expression.

Results

Membranous PODXL expression was significantly higher in primary PB-type (49.5 %) as compared with I-type (17.5 %) tumours. In PB-type tumours, PODXL expression was significantly associated with female sex (p = 0.005), location to the pancreas (p = 0.005), and poor differentiation grade (p = 0.044). Membranous PODXL expression was significantly associated with a reduced RFS (HR = 2.44, 95 % CI 1.10–5.44) and OS (HR = 2.32, 95 % CI 1.05–5.12) in I-type tumours and with a reduced RFS (HR = 1.63, 95 % CI 1.07–2.49) but not OS in PB-type tumours. PODXL remained a significant independent prognostic factor only in I-type tumours (HR = 5.12, 95 % CI 1.43–18.31 for RFS and HR = 7.31, 95 % CI 2.12–25.16 for OS). Patients with I-type tumours displaying membranous PODXL expression had a significant beneficial effect of adjuvant chemotherapy regarding 5-year OS.

Conclusion

Membranous expression of PODXL is significantly higher in PB-type than in I-type periampullary adenocarcinomas and an independent factor of poor prognosis in the latter. The results further indicate a beneficial effect of adjuvant chemotherapy on I-type tumours with membranous PODXL expression, suggesting the potential utility of PODXL as a biomarker for improved treatment stratification of these patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12907-015-0009-1) contains supplementary material, which is available to authorized users.