PODXL Expression Research Articles

Next-generation sequencing reveals hsa_circ_0058092 being a potential oncogene candidate involved in gastric cancer

Gastric cancer is a serious problem for human health. As part of noncoding RNA, circular RNA (circRNA) plays a key role in the occurrence and development of malignant tumor. We used next generation sequencing technology to detect circRNA expression profiles in 5 paired human gastric cancer tissues. Then, bioinformatics analysis was carried out to analyze the function of dysregulated circRNAs. Hsa_circ_0058092 was selected as the object of follow-up analysis. After using the Cistrome DB dataset the data was used to predict specific transcription factors of hsa_circ_0058092. The relationship between hsa_circ_0058092 and PODXL was further validated using RT-PCR and immunohistochemical techniques. Survival data were collected using a Kaplan-Meier analysis of hsa_circ_0058092. We identified 319 aberrantly expressed circRNAs, Hsa_circ_0058092 was selected for our studies. Functional analysis of hsa_circ_0058092 revealed that it was related to metabolic processes. The prediction results suggested that hsa_circ_0058092 has a relationship with hsa-miR-4269 which could specifically bind to the PODXL sequence. Transcription factor CEBPB may regulate the transcription process of hsa_circ_0058092. The expression of hsa_circ_0058092 was positively correlated with PODXL expression. Immunohistochemical analysis of PODXL showed that the expression of PODXL protein in cancer tissues is higher than that in adjacent tissues. Kaplan-Meier analysis suggested that hsa_circ_0058092 was associated with survival of gastric cancer patients. All of these results showed that hsa_circ_0058092 was a potential oncogene.

Inhibition of p38/MK2 Signaling Prevents Vascular Invasion of Melanoma

Melanoma cells can switch between distinct gene expression profiles, resulting in proliferative or invasive phenotypes. Signaling pathways involved in this switch were analyzed by gene expression profiling of a cohort of 22 patient-derived melanoma cell lines. CDH1 negativity was identified as a surrogate marker for the invasive phenotype. CDH1 expression could be turned on and off by modulating activity of p38 or its downstream target MK2, suggesting that this pathway controls melanoma progression. Mechanistically, MK2 inhibition prevented melanoma-induced vascular barrier disruption, reduced the expression of PODXL and DEL-1, and prevented vascular dissemination invivo. PODXL and DEL-1 expression in patients with melanoma were associated with poor survival and thus can be used as prognostic markers. Downstream targets of MK2 may thus serve as candidate therapeutics.

Podocalyxin is required for maintaining blood–brain barrier function during acute inflammation

Podocalyxin (Podxl) is broadly expressed on the luminal face of most blood vessels in adult vertebrates, yet its function on these cells is poorly defined. In the present study, we identified specific functions for Podxl in maintaining endothelial barrier function. Using electrical cell substrate impedance sensing and live imaging, we found that, in the absence of Podxl, human umbilical vein endothelial cells fail to form an efficient barrier when plated on several extracellular matrix substrates. In addition, these monolayers lack adherens junctions and focal adhesions and display a disorganized cortical actin cytoskeleton. Thus, Podxl has a key role in promoting the appropriate endothelial morphogenesis required to form functional barriers. This conclusion is further supported by analyses of mutant mice in which we conditionally deleted a floxed allele of Podxl in vascular endothelial cells (vECs) using Tie2Cre mice (PodxlΔTie2Cre). Although we did not detect substantially altered permeability in naïve mice, systemic priming with lipopolysaccharide (LPS) selectively disrupted the blood-brain barrier (BBB) in PodxlΔTie2Cre mice. To study the potential consequence of this BBB breach, we used a selective agonist (TFLLR-NH2) of the protease-activated receptor-1 (PAR-1), a thrombin receptor expressed by vECs, neuronal cells, and glial cells. In response to systemic administration of TFLLR-NH2, LPS-primed PodxlΔTie2Cre mice become completely immobilized for a 5-min period, coinciding with severely dampened neuroelectric activity. We conclude that Podxl expression by CNS tissue vECs is essential for BBB maintenance under inflammatory conditions.

Podocalyxin‐like protein promotes gastric cancer progression through interacting with RUN and FYVE domain containing 1 protein

Podocalyxin‐like protein (PODXL), a transmembrane glycoprotein with anti‐adhesive properties, is associated with an aggressive tumor phenotype and poor prognosis of several cancers. To elucidate the biological significance of PODXL and its molecular mechanism in gastric cancer (GC), we investigated the expression of PODXL in GC samples and assessed its effects on biological behaviors and the related signaling pathways in vitro and in vivo. Moreover, the possible and closely interacted partners of PODXL were identified. Our data showed that the protein or mRNA level of PODXL was significantly upregulated in tissues or serum of GC patients compared with normal‐appearing tissues (NAT) or those of healthy volunteers. Overall survival (OS) curves showed that patients with high PODXL levels in tissues or serum had a worse 5‐year OS. In vitro, restoring PODXL expression promoted tumor progression by increasing cell proliferation, colony formation, wound healing, migration and invasion, as well as suppressing the apoptosis. Furthermore, the PI3K/AKT, NF‐κB and MAPK/ERK signaling pathways were activated. There was a significant positive correlation between PODXL and RUN and FYVE domain containing 1 (RUFY1) expression in tissues or serum. Subsequent mass spectrometry analysis, co‐immunoprecipitation assays and western blot analysis identified PODXL/RUFY1 complexes in GC cells, and silencing RUFY1 expression in GC cells significantly attenuated PODXL‐induced phenotypes and their underlying signaling pathways. Our results suggested that PODXL promoted GC progression via a RUFY1‐dependent signaling mechanism. New GC therapeutic opportunities through PODXL and targeting the PODXL/RUFY1 complex might improve cancer therapy.

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

BackgroundWe 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).MethodsThe 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.ResultsThe 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.ConclusionsPatients 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.

Brg1 deficiency in vascular endothelial cells blocks neutrophil recruitment and ameliorates cardiac ischemia-reperfusion injury in mice

BackgroundIncreased neutrophil infiltration and the ensuing inflammatory response represent a hallmark event in cardiac ischemia-reperfusion injury (IRI). It remains poorly defined how the epigenetic machinery contributes to this process. Methods and resultsHere we report that mice with endothelial specific deletion of brahma related gene 1 (BRG1), a chromatin remodeling protein, exhibited amelioration when subjected to cardiac ischemia-reperfusion as evidenced by a reduction in infarct size as well as better recovery of heart function. Endothelial BRG1 deficiency also attenuated cardiac fibrosis following IRI when compared to wild type littermates. Interestingly, ablation of BRG1 in the endothelium suppressed neutrophil infiltration and down-regulated the levels of pro-inflammatory mediators in the heart following IRI. Further studies revealed that BRG1 activated the transcription of PODOCALYXIN (PODXL), an L-SELECTIN ligand crucial for neutrophil adhesion, in vascular endothelial cells in response to hypoxia-reoxygenation (HR). BRG1 knockdown by small interfering RNA abrogated HR-induced PODXL expression and blocked the adhesion of neutrophils to endothelial cells. Mechanistically, BRG1 alters the chromatin structure surrounding the PODXL promoter by interacting with JMJD2B, a histone H3K9 demethylase. Depletion of JMJD2B abrogated PODXL induction by HR and inhibited the adhesion of neutrophils to endothelial cells. ConclusionOur data suggest that trans-activation of PODXL by the BRG1-JMJD2B complex in endothelial cells may promote neutrophil infiltration and consequently the pathogenesis of cardiac ischemia-reperfusion injury.

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.

Novel roles for podocalyxin in regulating stress myelopoiesis, Rap1a, and neutrophil migration.

Podocalyxin (Podxl) is a CD34 orthologue and cell surface sialomucin reported to have roles in renal podocyte diaphragm slit development; vascular cell integrity; and the progression of blood, breast, and prostate cancers. Roles for Podxl during nonmalignant hematopoiesis, however, are largely undefined. We have developed a Vav-Cre Podxl knockout (KO) mouse model, and report on novel roles for Podxl in governing stress myelopoiesis. At steady state, Podxl expression among hematopoietic progenitor cells was low level but was induced by granulocyte colony-stimulating factor (G-CSF) in myeloid progenitors and by thrombopoietin in human stem cells. In keeping with low-level Podxl expression at steady state, Vav-Cre deletion of Podxl did not markedly alter peripheral blood cell levels. A G-CSF challenge in Podxl-KO mice, in contrast, hyperelevated peripheral blood neutrophil and monocyte levels. Podxl-KO also substantially heightened neutrophil levels after 5-fluorouracil myeloablation. These loss-of-function phenotypes were selective, and Podxl-KO did not alter lymphocyte, basophil, or eosinophil levels. Within bone marrow (and after G-CSF challenge), Podxl deletion moderately decreased colony forming units-granulocytes, eyrthrocytes, monocyte/macrophages, megakaryocytes and CD16/32posCD11bpos progenitors but did not affect Gr-1pos cell populations. Notably, Podxl-KO did significantly heighten peripheral blood neutrophil migration capacities. To interrogate Podxl's action mechanisms, a co-immunoprecipitation plus liquid chromatography-mass spectrometry approach was applied using hematopoietic progenitors from G-CSF-challenged mice. Rap1a, a Ras-related small GTPase, was a predominant co-retrieved Podxl partner. In bone marrow human progenitor cells, Podxl-KO led to heightened G-CSF activation of Rap1aGTP, and Rap1aGTP inhibition attenuated Podxl-KO neutrophil migration. Studies have revealed novel roles for Podxl as an important modulator of neutrophil and monocyte formation and of Rap1a activation during stress hematopoiesis.

Podocalyxin-like and RNA-binding motif protein 3 are prognostic biomarkers in urothelial bladder cancer: a validatory study

BackgroundUrothelial bladder cancer (UBC) is a disease that often is discovered when the tumour is non-muscle invasive, i.e. in Ta or T1 stage. Some patients will progress into muscle-invasive disease, a potentially deadly condition. Although there are some prognostic models, the need for prognostic and predictive biomarkers is considerate and urgent. Membranous expression of podocalyxin-like protein 1 (PODXL) and low expression of the RNA-binding motif 3 (RBM3) has previously been shown to be associated with an aggressive tumour phenotype and poor prognosis in several forms of cancer, including UBC. In this study, we sought to validate the prognostic impact of PODXL and RBM3 in an independent cohort of UBC.MethodsUsing tissue microarrays and immunohistochemistry, PODXL and RBM3 expression was evaluated in 272 incident UBC cases from the prospective, population-based cohort study Malmö Diet and Cancer. Kaplan-Meier analysis and Cox proportional hazards modelling were used to evaluate the prognostic impact of these markers on 5-year overall survival (OS).ResultsIn line with previous studies, both membranous PODXL expression and low RBM3 expression was significantly associated with disadvantageous clinicopathological features. Membranous PODXL expression was significantly associated with a reduced 5-year overall survival in the entire cohort (univariable HR 3.28; 95% CI 1.89–5.69), but this association did not remain significant in multivariable analysis. In T1 tumours, PODXL was significantly associated with reduced survival in univariable analysis (HR = 2.83; 95% CI 1.04–7.72) and borderline significant in multivariable analysis (HR = 2.60; 95% CI 0.91–7.39). Low RBM3 expression was an independent predictor of a reduced survival in the entire cohort (univariable HR 3.19; 95% CI 2.02–5.04, and multivariable HR 1.85; 95% CI 1.11–3.09), and in T1 tumours (univariable HR 2.64; 95% CI 1.11–6.27, and multivariable HR 2.63; 95% CI 1.01–6.84).ConclusionsA link between membranous PODXL expression and clinically more aggressive tumours was further confirmed, but PODXL expression was not an independent prognostic biomarker in this study. Low RBM3 expression was validated as an independent factor of poor prognosis in UBC, including T1 disease. These findings suggest that these biomarkers could be useful in stratifying patients with non-muscle invasive disease for more aggressive first line treatment.

Podocalyxin influences malignant potential by controlling epithelial-mesenchymal transition in lung adenocarcinoma.

Epithelial–mesenchymal transition (EMT) plays an important role in the progression of lung carcinoma. Podocalyxin (PODXL), which belongs to the CD34 family and regulates cell morphology, has been linked to EMT in lung cancer, and PODXL overexpression is associated with poor prognosis in several different classes of cancers. The aim of this study was to clarify the role of PODXL overexpression in EMT in lung cancer, and to determine the prognostic value of PODXL overexpression in tumors from lung cancer patients. The morphology, EMT marker expression, and migration and invasion abilities of engineered A549 PODXL‐knockdown (KD) or PODXL‐overexpression (OE) lung adenocarcinoma cells were examined. PODXL expression levels were assessed by immunohistochemistry in 114 human clinical lung adenocarcinoma specimens and correlated with clinical outcomes. PODXL‐KD cells were epithelial in shape, whereas PODXL‐OE cells displayed mesenchymal morphology. Epithelial markers were upregulated in PODXL‐KD cells and downregulated in PODXL‐OE cells, whereas mesenchymal markers were downregulated in the former and upregulated in the latter. A highly selective inhibitor of phosphatidylinositol 3‐kinase‐Akt signaling attenuated EMT of PODXL‐OE cells, while a transforming growth factor inhibitor did not, suggesting that PODXL induces EMT of lung adenocarcinoma cells via the phosphatidylinositol 3‐kinase pathway. In lung adenocarcinoma clinical specimens, PODXL expression was detected in minimally invasive and invasive adenocarcinoma, but not in non‐invasive adenocarcinoma. Disease free survival and cancer‐specific survival were significantly worse for patients whose tumors overexpressed PODXL. PODXL overexpression induces EMT in lung adenocarcinoma and contributes to tumor progression.

Prognostic role of podocalyxin-like protein expression in various cancers: A systematic review and meta-analysis.

Several studies were conducted to explore the prognostic significance of podocalyxin-like protein (PODXL) expression in various cancers, with contradictory. This study aims to summarize the prognostic significance of PODXL expression in cancers. PubMed, the Cochrane Library and Embase were completely retrieved. The prospective or retrospective studies focusing on the prognostic role of PODXL expression in cancers were eligible. The endpoints were overall survival (OS), disease-specific survival (DSS) and disease-free survival (DFS).12 studies involving a total of 5,309 patients were identified. The results indicated that high PODXL expression was significantly associated with worse OS when compared to the low PODXL expression (HR=1.76, 95%CI=1.53-2.04, p<0.00001; I2=41%, p=0.08). And similar results were detected in the subgroup analysis of analysis model, ethnicity, sample size, tumor type and antibody type. And the results also showed that high PODXL expression was obviously related to shorter DSS (HR=2.47, 95%CI=1.53-3.99, p=0.0002; I2=66%, p=0.03) and DFS (HR=2.12, 95%CI=1.58-2.85, p<0.00001; I2=19%, p=0.29). In conclusion, it was revealed that high PODXL expression is an unfavorable predictor of OS, DSS and DFS in patients with cancers, and high PODXL expression is a promising prognostic biomarker for cancers, especially for patients in European.

Podocalyxin-like protein, linked to poor prognosis of pancreatic cancers, promotes cell invasion by binding to gelsolin.

The cell‐adhesion glycoprotein PODXL is associated with an aggressive tumor phenotype in several forms of cancer. Here, we report that high PODXL expression was an independent predictor of worse overall survival of pancreatic cancer patients, and that PODXL promoted pancreatic cancer cell motility and invasion by physically binding to the cytoskeletal protein gelsolin. Suppression of PODXL or gelsolin decreased membrane protrusions with abundant peripheral actin structures, and in turn inhibited cell motility and invasion. Transfection of a PODXL‐rescue construct renewed the expression of gelsolin bound to peripheral actin structures in cell protrusions, and abrogated the decreased cell protrusions caused by the knockdown of PODXL. Furthermore, transfection of a PODXL‐rescue construct into pancreatic cancer cells in which both PODXL and gelsolin were suppressed failed to increase the formation of the protrusions. Thus, PODXL enhances motility and invasiveness through an increase in gelsolin–actin interactions in cell protrusions.

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

BackgroundPodocalyxin-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.MethodsThe 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.ResultsIn 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).ConclusionsIn 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.Electronic supplementary materialThe online version of this article (doi:10.1186/s12907-016-0034-8) contains supplementary material, which is available to authorized users.

Significant association and synergistic adverse prognostic effect of podocalyxin-like protein and epidermal growth factor receptor expression in colorectal cancer.

BackgroundPodocalyxin-like 1 (PODXL) is an anti-adhesive transmembrane protein that has been demonstrated to be an independent factor of poor prognosis in colorectal cancer (CRC). The gene encoding PODXL is located to chromosome 7, which also harbours the gene for the epidermal growth factor receptor (EGFR). The aim of this study was to examine the associations between PODXL and EGFR expression in CRC in vitro and in vivo.MethodsEGFR expression was analysed in tumours from three independent patient cohorts; cohort 1 (n = 533), cohort 2 (n = 259) and cohort 3 (n = 310), previously analysed for immunohistochemical PODXL expression and KRAS and BRAF mutations (cohort 1 and 3). Levels of EGFR and PODXL were determined by western blot in six different CRC cell lines.ResultsHigh expression of PODXL was significantly associated with high EGFR expression (p < 0.001) in all three cohorts, and with BRAF mutation (p < 0.001) in cohort 1 and 3. High EGFR expression correlated with BRAF mutation (p < 0.001) in cohort 1. High EGFR expression was associated with adverse clinicopathological factors and independently predicted a reduced 5-year overall survival (OS) in cohort 1 (HR 1.77; 95 % CI 1.27–2.46), cohort 2 (HR 1.58; 95 % CI 1.05–2.38) and cohort 3 (HR 1.83; 95 % CI 1.19–2.81). The highest risk of death within 5 years was observed in patients with tumours displaying high expression of both EGFR and PODXL in cohort 1 and 3 (HR 1.97; 95 % CI 1.18–3.28 and HR 3.56; 95 % CI 1.75–7.22, respectively). Western blot analysis showed a uniform expression of PODXL and EGFR in all six examined CRC cell lines.ConclusionsThe results from this study demonstrate that high expression of EGFR is an independent factor of poor prognosis in CRC. Moreover, strong links have been uncovered between expression of the recently proposed biomarker candidate PODXL with EGFR expression in CRC in vivo and in vitro, and with BRAF mutation in vivo. High expression of both PODXL and EGFR may also have a synergistic adverse effect on survival. These findings suggest a potential functional link in CRC between PODXL, EGFR and BRAF, all originating from chromosome 7, which may be highly relevant in the clinical setting and therefore merit future in-depth study.Electronic supplementary materialThe online version of this article (doi:10.1186/s12967-016-0882-0) contains supplementary material, which is available to authorized users.

Podocalyxin as a Prognostic Marker in Gastric Cancer.

BackgroundPodocalyxin-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.MethodsBy 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.ResultsPODXL 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).ConclusionIn gastric cancer, PODXL expression by the polyclonal antibody HPA2110 is an independent marker of poor prognosis.

Podocalyxin Negatively Regulates Stress Myelopoiesis, Directly Binds Rap-1A and Modulates Its G-CSF-Induced Activity

Podocalyxin (PodxL) is a CD34 family member previously identified to mark hematopoietic stem cells (HSCs) and other progenitor cells. Previously, we discovered PodxL as a potent erythropoietin (EPO) response gene and demonstrated to promote egression of immature reticulocytes from bone marrow into circulation. PodxL is upregulated in several cancers, including myeloid and lymphoid leukemia. Herein, we aim to define the functional role of PodxL in hematopoiesis - specifically myelopoiesis - by employing conditional PodxL knock out (KO) mouse models. Hematopoietic-specific deletion was achieved using Cre mice with a Vav1 driver and myeloid-specific deletion was achieved with Lyzm2 - Cre driver. We confirmed the deletion of exons 3-7 at the gene, transcript and protein levels using PCR, RT-qPCR and western blotting, respectively. Peripheral blood analysis revealed no difference in blood cell lineages for either KO mouse strain. At steady state, colony forming unit-granulocyte/macrophage (CFU-GM) assay also showed no difference between the KO strains and wild type. In order to examine the functional role of PodxL during stress myelopoiesis, PodxL-/- ; Vav1-Cre mice were treated with 5-Fluorouracil (5FU), a chemotherapeutic agent induces myeloablation. Notably, during rebound of neutrophils, the PodxL-/- ; Vav1-Cre mice showed a sharp increase in neutrophil counts at day 12.5, which at later time points reverted to normal levels comparable to wild type mice. Previously, our in silico analyses combined with outcomes from truncated EpoR knock-in alleles had revealed that PodxL is a potential STAT5 transcriptional target. Here, we tested if G-CSF induces PodxL expression in hematopoietic progenitors. In vivo, G-CSF significantly induced PodxL expression four fold. We then tested the role of PodxL in G-CSF induced neutrophil formation in vivo. Both KO strains (Podxl-/-;Vav1-Cre and Podxl-/-;Lyzm2-Cre) and wild type were treated with G-CSF (125ug/kg/day) for 5 days. Peripheral blood analysis revealed increased neutrophil and monocyte levels in the PodxL-/-;Vav1-Cremice. In order to then determine a possible role of PodxL at the progenitor level, CFU-GM assays were performed. PodxL-/- ; lyzm2-Cre mice had increased colony forming capabilities but there was no difference in PodxL-/-;Vav1-Cre mice compared to wild type. Our results imply that PodxL is playing a negative regulatory role in stress myelopoiesis. Interestingly, the deletion of PodxL in hematopoietic progenitors (Vav1-Cre) resulted in enhanced migration of neutrophils, whereas deletion of PodxL in myeloid compartment (Lyzm2-Cre) resulted in decreased neutrophil migration. This may be in part due to a compensatory effect by CD34 in the hematopoietic compartment. To dissect the molecular mechanism of PodxL during stress myelopoiesis, upon in vivo G-CSF treatment, bone marrow derived hematopoietic progenitors were isolated and PodxL protein was immunoprecipitated. LC-MS/MS proteomic analysis was performed to identify the interacting partners with PodxL. Rap-1A, a small GTPase and member of the RAS family, was among the top interacting proteins. Rap-1A has been shown to promote adhesion and migration of myeloid cells. The association of PodxL with Rap-1A was further confirmed in hematopoietic progenitors by immunoprecipitation and western blotting. To determine if the interaction of PodxL directly regulates Rap-1A activity, a GTP-Rap-1A activity assay was performed in response to G-CSF, GM-CSF and IL-3. Rap-1A activity was significantly elevated in hematopoietic progenitors upon G-CSF treatment in PodxL-/-:Vav1-Cre mice compared to wild type, followed by IL3; however, GM-CSF did not affect Rap-1A activity. In conclusion, our results indicate an important functional role for PodxL in stress myelopoiesis, a function likely mediated via Rap-1A. A complete understanding of the PodxL/Rap-1A axis may reveal important molecular insights into G-CSF-induced mobilization of neutrophils and provide mechanistic understanding into the pathological role of PodxL in aggressive cancers, including leukemia, which in turn may facilitate identification of novel therapeutic targets in PodxL associated cancers. DisclosuresNo relevant conflicts of interest to declare.

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

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

564P - Association and Prognostic Interaction of Podocalyxin Like-Protein with Epidermal Growth Factor Receptor Alterations in Colorectal Cancer: a Cohort Study

ABSTRACT Aim: Podocalyxin-like 1 (PODXL) is an anti-adhesive transmembrane glycoprotein and stem cell marker that has been demonstrated to be an independent factor of poor prognosis in colorectal cancer (CRC). The gene encoding PODXL is located to chromosome 7, which also harbours the gene for the epidermal growth factor receptor (EGFR). High expression of EGFR correlates with poor prognosis in CRC, and EGFR gene copy number (gcn) alterations with responsiveness to anti-EGFR drugs. In this study, we examined the associations between PODXL expression and EGFR expression and gcn alterations, as well as KRAS and BRAF mutations, in a large, prospective CRC cohort. Methods: Using immunohistochemistry and brightfield dual-in situ hybridization, EGFR expression and EGFR gcn alterations (amplification or polysomy) was assessed in tumours from 557 incident CRC cases in the Malmo Diet and Cancer Study, previously analysed for immunohistochemical PODXL expression, KRAS and BRAF mutation status. Results: Overexpression of PODXL was significantly associated with high EGFR expression (p Conclusions: The results from this study demonstrate that overexpression of PODXL is associated with high EGFR expression and BRAF mutation in CRC. Moreover, a significant interaction of PODXL and EGFR alterations on the risk of death within 5 years was observed. These findings suggest a functional link between PODXL and the well-established oncogene EGFR, further corroborating the role of PODXL as a biomarker of poor prognosis in CRC and also indicating a possible involvement of PODXL in the responsiveness to anti-EGFR treatment, which may be of considerable clinical importance. Disclosure: All authors have declared no conflicts of interest.

Podocalyxin is a marker of poor prognosis in colorectal cancer.

BackgroundOver two decades ago, a proposal was that two different colorectal cancer (CRC) entities existed, based on tumour location either proximal (right) or distal (left) of the splenic flexure. Proximal and distal tumours exhibit different clinical, epidemiological, and biological characteristics. Improvement of the prognostic evaluation of CRC requires new molecular markers. Podocalyxin-like 1 (PODXL), an anti-adhesive transmembrane sialomucin, is associated with an aggressive tumour phenotype and poor prognosis. For colorectal cancer, it has been suggested to be a marker of poor prognosis. The aim of this study was to investigate the role of PODXL in CRC by use of a novel monoclonal antibody.MethodsIn 1983–2001, 840 consecutive colorectal cancer patients were treated at Helsinki University Central Hospital, of whom 767 were successfully scored for PODXL immunohistochemical expression from tumour tissue microarrays by use of a novel monoclonal in-house antibody. Associations of PODXL expression and tumour location with other clinicopathological variables were explored by Fisher’s exact-test, linear-by- linear association test, and binary logistic regression. Survival analyses were done by the Kaplan-Meier method and Cox proportional hazards model.ResultsPODXL protein expression was high in 44 (5.7%) specimens. High expression associated strongly with poor differentiation (p < 0.0001), advanced stage (p = 0.011), and location of the tumour in the right hemicolon (RHC) (p < 0.001). Tumours of the RHC were more poorly differentiated (p < 0.0001) and showed higher PODXL expression (p < 0.001).High PODXL expression associated significantly with higher risk for disease-specific death from CRC (hazard ratio (HR) = 2.00; 95% confidence interval (CI) 1.31–3.06, p = 0.001) and also in the subgroups of left hemicolon (LHC) cancers (HR = 2.60; 95% CI 1.45–4.66, p = 0.001) and rectal cancers (HR = 3.03; 95% CI 1.54–5.60, p = 0.001). Results remained significant in multivariable analysis (respectively, HR = 1.82; 95% CI 1.15–2.86, p = 0.01; HR = 2.59; 95% CI 1.41–4.88, p = 0.002; and HR = 2.69; 95% CI 1.30–5.54, p = 0.007).ConclusionPodocalyxin was an independent factor for poor prognosis in colorectal cancer and in the subgroups of left hemicolon and rectum. This is, to our knowledge, the first evidence of such difference in PODXL expression, its function possibly being dependent upon tumour location.

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

BackgroundPodocalyxin (PODXL) is a transmembrane sialomucin, whose aberrant expression and/or allelic variation associates with poor prognosis and unfavourable clinicopathological characteristics in different cancers. Membranous expression of PODXL has been suggested to be an independent marker of poor prognosis in colorectal cancer (CRC), and previously by an in-house monoclonal antibody, we showed that also cytoplasmic overexpression of PODXL predicts poor prognosis. The aim of this study was to compare two PODXL antibodies with different epitopes case-by-case in CRC patients.MethodsOf 840 consecutively operated CRC patients from Helsinki University Central Hospital, PODXL expression by polyclonal HPA 2110 antibody was evaluated from 780. Associations of PODXL expression with clinicopathological parameters and the impact of PODXL expression on survival were assessed. Kappa-value was used to assess the comparability of the two antibodies.ResultsMembranous PODXL expression associated with unfavourable clinicopathological parameters and with higher risk for disease-specific death from CRC within 5 years (unadjusted hazard ratio (HR) = 1.90; 95% confidence interval (CI) (1.32-2.75); adjusted HR = 1.64; 95% CI (1.11-2.43)). The comparability of expressions by the two antibodies was low (kappa =0.219, standard error 0.060, p < 0.0001). Combination of two antibodies identified a group of patients with even worse prognosis (unadjusted HR = 6.00; 95% CI (3.27-13.0); adjusted HR = 2.14; 95% CI (1.12-4.07)).ConclusionMembranous expression by the polyclonal PODXL antibody and cytoplasmic overexpression by the monocolonal PODXL antibody are both independent markers of poor prognosis, but they recognise different groups of patients, both of which have poor prognosis. The combined use of the antibodies reveals a group with an even worse prognosis. The biological reasons for the difference between antibodies warrant further studies.