Down-regulation of the polymeric immunoglobulin receptor in non-small cell lung carcinoma: correlation with dysregulated expression of the transcription factors USF and AP2

Expression of polymeric immunoglobulin receptor (PIGR) and the effect of PIGR overexpression on breast cancer cells

Polymeric immunoglobulin receptor (PIGR) has a major role in mucosal immunity as a transporter of polymeric immunoglobulin across the epithelial cells. The aim of this study was to determine the effect of PIGR on cellular behaviours and chemo-sensitivity of MCF7 and MDA-MB468 breast cancer cell lines. Basal levels of PIGR mRNA and protein expression in MCF7 and MDA-MB468 cells were evaluated by real time quantitative polymerase chain reaction and Western blotting, respectively. MCF7/PIGR and MDA-MB468/PIGR stable cell lines, overexpressing the PIGR gene, were generated using a lentiviral vector with tetracycline dependent induction of expression. Cell viability, cell proliferation and chemo-sensitivity of PIGR transfected cells were evaluated and compared with un-transfected cells to determine the effect of PIGR overexpression on cell phenotype. The levels of PIGR mRNA and protein expression were significantly higher in MDA-MB468 cells than in MCF7 cells (380-fold, p < 0.0001). However, the differential expression of PIGR in these two cell lines did not lead to significant differences in chemosensitivity. Viral overexpression of PIGR was also not found to change any of the parameters measured in either cell line. PIGR per se did not affect cellular behaviours and chemosensitivity of these breast cancer cell lines.

M1 macrophages evoke an increase in polymeric immunoglobulin receptor (PIGR) expression in MDA-MB468 breast cancer cells through secretion of interleukin-1β

High expression of polymeric immunoglobulin receptor (PIGR) in breast cancer is associated with increased 5-year survival rate. However, the factors influencing PIGR expression in breast cancer have not been elucidated. The aim of this study was to determine the role of macrophages and cytokines affecting expression of PIGR in two breast cancer cell lines. M1, M2 macrophage conditioned media (CM) and recombinant human cytokines were used to determine factors which increased PIGR expression in MCF7 (HTB-22) and MDA-MB468 (HTB-132) breast cancer cell lines. The level of PIGR expression in the cells and PIGR secretory component were evaluated by real-time quantitative polymerase chain reaction and Western blotting. M1 macrophage CM induced a dose-dependent increase in PIGR mRNA expression in MDA-MB468 cells, up to 20-fold. The level of PIGR expression in MCF7 cells was very low and not affected by M1 and M2 CM. Interferon gamma (IFN-γ) and interleukin (IL)-1β also increased PIGR expression in MDA-MB468 and MCF7 cells. However, IL-1β was demonstrated to increase in M1 macrophages, while IFN-γ was not. The role of IL-1β secreted from M1 macrophages in increasing expression of PIGR was confirmed by IL-1 receptor blockade, indicating that IL-1β was the major M1 macrophage-derived cytokine that enhanced PIGR expression. Elevated PIGR expression in breast cancer in vivo may reflect the polarization state of tumor-associated immune cells.

Patient pIgR-enriched extracellular vesicles drive cancer stemness, tumorigenesis and metastasis in hepatocellular carcinoma

BACKGROUND & AIMS

Extracellular vesicles (EVs) play a pivotal role in connecting tumor cells with their local and distant microenvironments. Herein, we aimed to understand the role (on a molecular basis) patient-derived EVs play in modulating cancer stemness and tumorigenesis in the context of hepatocellular carcinoma (HCC).

METHODS

EVs from patient sera were isolated, quantified and characterized. The EVs were vigorously tested, both in vitro and in vivo, through various functional assays. Proteomic analysis was performed to identify the functional components of EVs. The presence and level of polymeric immunoglobulin receptor (pIgR) in circulating EVs and tumor and non-tumorous tissues of patients with HCC were determined by ELISA, immunoblotting, immunohistochemistry and quantitative PCR. The functional role and underlying mechanism of EVs with enhanced pIgR expression were elucidated. Blockade of EV-pIgR with neutralizing antibody was performed in nude mice implanted with patient-derived tumor xenografts (PDTXs).

RESULTS

Circulating EVs from patients with late-stage HCC (L-HCC) had significantly elevated pIgR expression compared to the EVs released by control individuals. The augmenting effect of L-HCC-EVs on cancer stemness and tumorigenesis was hindered by an anti-pIgR antibody. EVs enriched with pIgR consistently promoted cancer stemness and cancerous phenotypes in recipient cells. Mechanistically, EV-pIgR-induced cancer aggressiveness was abrogated by Akt and β-catenin inhibitors, confirming that the role of EV-pIgR depends on the activation of the PDK1/Akt/GSK3β/β-catenin signaling axis. Furthermore, an anti-pIgR neutralizing antibody attenuated tumor growth in mice implanted with PDTXs.

CONCLUSIONS

This study illustrates a previously unknown role of EV-pIgR in regulating cancer stemness and aggressiveness: EV-pIgR activates PDK1/Akt/GSK3β/β-catenin signaling cascades. The blockade of the intercellular communication mediated by EV-pIgR in the tumor microenvironment may provide a new therapeutic strategy for patients with cancer.

LAY SUMMARY

The World Health Organization estimates that more than 1 million patients will die from liver cancer, mostly hepatocellular carcinoma (HCC), in 2030. Understanding the underlying mechanism by which HCC acquires aggressive attributes is crucial to improving the diagnosis and treatment of patients. Herein, we demonstrated that nanometer-sized extracellular vesicles released by tumors promote cancer stemness and tumorigenesis. Within these oncogenic vesicles, we identified a key component that functions as a potent modulator of cancer aggressiveness. By inhibiting this functional component of EVs using a neutralizing antibody, tumor growth was profoundly attenuated in mice. This hints at a potentially effective therapeutic alternative for patients with cancer.

System analysis of FHIT in LUAD and LUSC: The expression, prognosis, gene regulation network, and regulation targets

BACKGROUND

Fragile histidine triad (FHIT) is a strong tumor suppressor gene, and cells deficient in FHIT are prone to acquiring cancer-promoting mutations. Due to its location, deletions within FHIT are common in cancer. Over 50% of cancers show loss of FHIT expression. However, to date, expression levels, gene regulatory networks, prognostic value, and target prediction of FHIT in lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC) have not been fully reported. Therefore, systematic analysis of FHIT expression, gene regulatory network, prognostic value, and targeted prediction in patients with LUAD and LUSC has important guiding significance, providing new therapeutic targets and strategies for clinical treatment of lung cancer to further improve the therapeutic effect of lung cancer.

METHODS

Multiple free online databases were used for the abovementioned analysis in this study, including cBioPortal, TRRUST, Human Protein Atlas, GeneMANIA, GEPIA, Metascape, UALCAN, LinkedOmics, and TIMER.

RESULTS

FHIT was upregulated in patients with LUAD, and downregulated in patients with LUSC. Genetic alterations of FHIT were found in patients with LUAD (7%), and LUSC (10%). The promoter methylation of FHIT was lower in patients with LUAD and LUSC. FHIT expression significantly correlated with LUSC pathological stages. Furthermore, patients with LUAD and LUSC having low FHIT expression levels had a longer survival than those having high FHIT expression levels. FHIT and its neighboring genes (the 50 most frequently altered neighboring genes of FHIT) functioned in the regulation of protein kinase and DNA binding in patients with LUAD, as well as cell channels and membrane potential in patients with LUSC. Gene ontology enrichment analysis revealed that the functions of FHIT and its neighboring genes are mainly related to disordered domain-specific binding, protein kinase binding, and ion gated channel activity in patients with LUAD, as well as calcium ion binding and intracellular ligand-gated ion channel activity in patients with LUSC. Transcription factor targets of FHIT and its neighboring genes in patients with lung cancer were found: USF1, SOX6, USF2, SIRT1, VHL, LEF1, EZH2, TP53, HDAC1, ESR1, EGR1, YY1, MYC, RELA, NFKB1, and E2F1 in LUAD; and HDAC1, DNMT1, and E2F1 in LUSC. We further explored the FHIT-associated kinase (PRKCQ, AURKB and ATM in LUAD as well as PLK3 in LUSC) and FHIT-associated miRNA targets (MIR-188, MIR-323, and MIR-518A-2 in LUAD). Furthermore, the following genes had the strongest correlation with FHIT expression in patients with lung cancer: NICN1, HEMK1, and BDH2 in LUAD, and ZMAT1, TTC21A, and NICN1 in LUSC. FHIT expression was positively associated with immune cell infiltration (B cell) in patients with LUAD, as well as B cell, CD8 + T, CD4 + T cells, macrophages, and dendritic cells in patients with LUSC. Nevertheless, FHIT expression was negatively associated with CD8 + T cells and neutrophils in patients with LUAD.

CONCLUSIONS

The expression, gene regulatory network, prognostic value and targeted prediction of FHIT in patients with LUAD and LUSC were systematically analyzed and revealed in this study, thereby laying a foundation for further research on the role of FHIT in LUAD and LUSC occurrence. This study provides new LUAD and LUSC therapeutic targets and prognostic biomarkers as a reference for fundamental and clinical research.

Exogenous and Endogenous Triggers Differentially Stimulate Pigr Expression and Antibacterial Secretory Immunity in the Murine Respiratory Tract

PURPOSE

Transport of secretory immunoglobulin A (SIgA) through the airway epithelial cell barrier into the mucosal lumen by the polymeric immunoglobulin receptor (pIgR) is an important mechanism of respiratory mucosal host defense. Identification of immunomodulating substances that regulate secretory immunity might have therapeutic implications with regard to an improved immune exclusion. Thus, we sought to analyze secretory immunity under homeostatic and immunomodulating conditions in different compartments of the murine upper and lower respiratory tract (URT&LRT).

METHODS

Pigr gene expression in lung, trachea, and nasal-associated lymphoid tissue (NALT) of germ-free mice, specific pathogen-free mice, mice with an undefined microbiome, as well as LPS- and IFN-γ-treated mice was determined by quantitative real-time PCR. IgA levels in bronchoalveolar lavage (BAL), nasal lavage (NAL), and serum were determined by ELISA. LPS- and IFN-γ-treated mice were colonized with Streptococcus pneumoniae and bacterial CFUs were determined in URT and LRT.

RESULTS

Respiratory Pigr expression and IgA levels were dependent on the degree of exposure to environmental microbial stimuli. While immunostimulation with LPS and IFN-γ differentially impacts respiratory Pigr expression and IgA in URT vs. LRT, only prophylactic IFN-γ treatment reduces nasal colonization with S. pneumoniae.

CONCLUSION

Airway-associated secretory immunity can be partly modulated by exposure to microbial ligands and proinflammatory stimuli. Prophylactic IFN-γ-treatment modestly improves antibacterial immunity in the URT, but this does not appear to be mediated by SIgA or pIgR.

miR-181b inhibits chemoresistance in cisplatin-resistant H446 small cell lung cancer cells by targeting Bcl-2

INTRODUCTION

MicroRNAs (miRNAs) are a group of small non-coding RNAs that affect multiple aspects of tumor biology including chemo resistance. miR-181b has been reported to modulate multidrug resistance in non-small cell lung cancer cells. This study was undertaken to determine the role of miR-181b in chemo resistance of small cell lung cancer cells.

MATERIAL AND METHODS

This study was undertaken to determine the role of miR-181b in chemoresistance of small cell lung cancer cells with use of qRt-PCR, WB, bioinformatics analysis, and double luciferase reporter system.

RESULTS

Our data showed that miR-181b was significantly downregulated in cisplatin-resistant H446 small cell lung cancer cells, compared to parental cells, compared to parental cells. Ectopic expression of miR-181b inhibited cell proliferation and invasion in cisplatin-resistant H446 cells (p = 0.023). Moreover, overexpression of miR-181b increased the susceptibility of cisplatin-resistant H446 cells to cisplatin. Mechanistic investigations demonstrated that miR-181b inhibited B-cell lymphoma-2 (Bcl-2) expression by binding to the 3'-untranslated region. Overexpression of Bcl-2 reversed miR-181b-mediated chemo sensitization, which is accompanied by a reduced apoptotic response.

CONCLUSIONS

Taken together, this work demonstrated that miR-181b might have the ability to overcome chemo resistance of small cell lung cancer cells, and restoration of this miRNA may represent a potential therapeutic strategy for improving chemo sensitivity in small cell lung cancer.

Genome-wide profiling of long non-coding RNA expression patterns in the EGFR-TKI resistance of lung adenocarcinoma by microarray

Mutations in the epidermal growth factor receptor (EGFR) make lung adenocarcinoma cells sensitive to EGFR tyrosine kinase inhibitors (TKIs). Long-term cancer therapy may cause the occurrence of acquired resistance to EGFR TKIs. Long non-coding RNAs (lncRNAs) play important roles in tumor formation, tumor metastasis and the development of EGFR-TKI resistance in lung cancer. To gain insight into the molecular mechanisms of EGFR-TKI resistance, we generated an EGFR-TKI-resistant HCC827-8-1 cell line and analyzed expression patterns by lncRNA microarray and compared it with its parental HCC827 cell line. A total of 1,476 lncRNA transcripts and 1,026 mRNA transcripts were dysregulated in the HCC827‑8-1 cells. The expression levels of 7 chosen lncRNAs were validated by real-time quantitative PCR. As indicated by functional analysis, several groups of lncRNAs may be involved in the bio-pathways associated with EGFR-TKI resistance through their cis- and/or trans‑regulation of protein-coding genes. Thus, lncRNAs may be used as novel candidate biomarkers and potential targets in EGFR-TKI therapy in the future.

Reduced expression of the polymeric immunoglobulin receptor in pancreatic and periampullary adenocarcinoma signifies tumour progression and poor prognosis

The polymeric immunoglobulin receptor (pIgR) is a key component of the mucosal immune system that mediates epithelial transcytosis of immunoglobulins. High pIgR expression has been reported to correlate with a less aggressive tumour phenotype and an improved prognosis in several human cancer types. Here, we examined the expression and prognostic significance of pIgR in pancreatic and periampullary adenocarcinoma. The study cohort encompasses a consecutive series of 175 patients surgically treated with pancreaticoduodenectomy for pancreatic and periampullary adenocarcinoma in Malmö and Lund University Hospitals, Sweden, between 2001–2011. Tissue microarrays were constructed from primary tumours (n = 175) and paired lymph node metastases (n = 105). A multiplied score was calculated from the fraction and intensity of pIgR staining. Classification and regression tree analysis was used to select the prognostic cut-off. Unadjusted and adjusted hazard ratios (HR) for death and recurrence within 5 years were calculated. pIgR expression could be evaluated in 172/175 (98.3%) primary tumours and in 96/105 (91.4%) lymph node metastases. pIgR expression was significantly down-regulated in lymph node metastases as compared with primary tumours (p = 0.018). Low pIgR expression was significantly associated with poor differentiation grade (p<0.001), perineural growth (p = 0.027), lymphatic invasion (p = 0.016), vascular invasion (p = 0.033) and infiltration of the peripancreatic fat (p = 0.039). In the entire cohort, low pIgR expression was significantly associated with an impaired 5-year survival (HR = 2.99, 95% confidence interval (CI) 1.71–5.25) and early recurrence (HR = 2.89, 95% CI 1.67–4.98). This association remained significant for survival after adjustment for conventional clinicopathological factors, tumour origin and adjuvant treatment (HR = 1.98, 95% CI 1.10–3.57). These results demonstrate, for the first time, that high tumour-specific pIgR expression signifies a more favourable tumour phenotype and that low expression independently predicts a shorter survival in patients with pancreatic and periampullary cancer. The mechanistic basis for the putative tumour suppressing properties of pIgR in these cancers merits further study.

Polymeric immunoglobulin receptor expression is correlated with poor prognosis in patients with osteosarcoma

The prognosis of patients with osteosarcoma with distant metastasis and local recurrence remains poor. Increased expression of polymeric immunoglobulin receptor (pIgR) in tumor tissue has been detected in various types of cancer. However, the clinical significance of pIgR in osteosarcoma has yet to be elucidated. The present study aimed to investigate the prognostic value of pIgR in patients with osteosarcoma following surgical resection. pIgR expression was assessed using quantitative polymerase chain reaction analysis in cryopreserved osteosarcoma tissues from 22 patients, as well as using immunohistochemistry in paraffin-embedded osteosarcoma tissues from 136 patients. The association between pIgR expression, clinicopathological factors and long-term prognosis was retrospectively examined in these 136 patients. The prognostic significance of negative or positive pIgR expression in osteosarcoma was assessed using Kaplan-Meier survival analysis and log-rank tests. Univariate analysis indicated that patients with positive pIgR osteosarcoma tissue expression had a significantly worse overall survival (OS) compared with patients with negative pIgR osteosarcoma expression. Multivariate analysis revealed that positive pIgR expression in osteosarcoma tissues was an independent prognostic factor for OS following surgical resection (P<0.001). Furthermore, positive pIgR expression was significantly associated with poor prognosis in patients with osteosarcoma. These findings indicate that pIgR may be a novel predictor for poor prognosis in patients with osteosarcoma following surgical resection.

Expression and prognostic significance of the polymeric immunoglobulin receptor in esophageal and gastric adenocarcinoma

INTRODUCTION

The polymeric immunoglobulin receptor (PIGR) has been proposed to be a candidate prognostic biomarker in a few cancer forms, and one previous study reported that reduced PIGR expression signifies more aggressive tumours of the distal esophagus and gastroesophageal junction (GEJ). In the present study, we examined the expression, clinicopathological correlates and prognostic significance of PIGR expression in an extended cohort of adenocarcinoma of the upper gastrointestinal tract.

MATERIALS AND METHODS

Immunohistochemical PIGR expression was examined in a consecutive cohort of patients with surgically resected, radio-chemonaive adenocarcinoma of the esophagus, GE-junction and stomach (n = 173), including paired samples of benign-appearing squamous epithelium (n = 51), gastric mucosa (n = 114), Barrett's esophagus (BE) or intestinal metaplasia (IM) (n = 57) and lymph node metastases (n = 75). Non-parametric tests were applied to explore associations between PIGR expression in primary tumours and clinicopathological characteristics. Classification and regression tree analysis was applied for selection of prognostic cut-off. The impact of PIGR expression on overall survival (OS) and recurrence-free survival (RFS) was assessed by Kaplan-Meier analysis and hazard ratios (HR) calculated by adjusted and unadjusted Cox proportional hazards modelling.

RESULTS

PIGR expression was significantly higher in intestinal metaplasia (BE or gastric IM) compared to normal tissues and cancer (p < 0.001). Reduced PIGR expression in primary tumours was significantly associated with more advanced tumour stage (p = 0.002) and inversely associated with involved margins (p = 0.034). PIGR expression did not differ between primary tumours and lymph node metastases. There was no significant difference in PIGR expression between tumours with and without a background of intestinal metaplasia. High PIGR expression was an independent predictor of a prolonged OS (HR = 0.60, 95% CI 0.36-0.99) and RFS (HR = 0.49, 95% CI 0.27-0.90) in patients with radically resected (R0) primary tumours and of an improved RFS (HR = 0.32, 95% CI 0.15-0.69) in curatively treated patients with R0 resection/distant metastasis-free disease.

CONCLUSION

High PIGR expression independently predicts a decreased risk of recurrence and an improved survival in patients with adenocarcinoma of the upper gastrointestinal tract. These findings are of potential clinical relevance and merit further validation.

Expression and prognostic significance of the polymeric immunoglobulin receptor in epithelial ovarian cancer

BACKGROUND

High expression of the polymeric immunoglobulin receptor (PIGR) has previously been associated with a favourable prognosis in a few cancer forms, but its expression and relationship with clinical outcome in epithelial ovarian cancer (EOC) has not yet been reported. The aim of this study was therefore to examine the clinicopathological correlates and prognostic significance of PIGR expression in EOC.

METHODS

After an initial screening in the Human Protein Atlas portal, a validated antibody was selected for extended analysis of immunohistochemical PIGR expression in tissue microarrays with tumours from 154 incident cases of EOC from two pooled prospective population-based cohorts. Subsets of corresponding benign-appearing fallopian tubes (n = 38) and omental metastases (n = 33) were also analysed. Kaplan-Meier analysis and Cox regression analysis were applied to examine the impact of PIGR expression on overall survival (OS) and ovarian cancer-specific survival (OCSS).

RESULTS

PIGR expression was significantly higher in fallopian tubes compared to primary tumours and metastases (p < 0.001) and lower in carcinoma of the serous subtype compared to other carcinomas (p < 0.001). PIGR expression was significantly associated with lower grade (p = 0.001), mucinous histological subtype (p = 0.002), positive progesterone receptor expression (p = 0.009) and negative or low Ki-67 expression (p = 0.003). Kaplan-Meier analysis revealed a significantly improved OS (p = 0.013) and OCSS (p = 0.009) for patients with tumours displaying high expression of PIGR. These associations were confirmed in unadjusted Cox regression analysis (HR = 0.48; 95% CI 0.26-0.87; p = 0.015 for OS and HR = 0.43, 95% CI 0.22-0.82; p = 0.011 for OCSS) but did not remain significant after adjustment for age, grade and clinical stage.

CONCLUSIONS

This study provides a first demonstration of PIGR expression in human fallopian tubes, primary EOC tumours and metastases. High tumour-specific expression of PIGR was found to be associated with a favourable prognosis in unadjusted, but not in adjusted, analysis. These findings are novel and merit further investigation.

Molecular profiling of multiple human cancers defines an inflammatory cancer-associated molecular pattern and uncovers KPNA2 as a uniform poor prognostic cancer marker

BACKGROUND

Immune evasion is one of the recognized hallmarks of cancer. Inflammatory responses to cancer can also contribute directly to oncogenesis. Since the immune system is hardwired to protect the host, there is a possibility that cancers, regardless of their histological origins, endow themselves with a common and shared inflammatory cancer-associated molecular pattern (iCAMP) to promote oncoinflammation. However, the definition of iCAMP has not been conceptually and experimentally investigated.

METHODS AND FINDINGS

Genome-wide cDNA expression data was analyzed for 221 normal and 324 cancer specimens from 7 cancer types: breast, prostate, lung, colon, gastric, oral and pancreatic. A total of 96 inflammatory genes with consistent dysregulation were identified, including 44 up-regulated and 52 down-regulated genes. Protein expression was confirmed by immunohistochemistry for some of these genes. The iCAMP contains proteins whose roles in cancer have been implicated and others which are yet to be appreciated. The clinical significance of many iCAMP genes was confirmed in multiple independent cohorts of colon and ovarian cancer patients. In both cases, better prognosis correlated strongly with high CXCL13 and low level of GREM1, LOX, TNFAIP6, CD36, and EDNRA. An "Inflammatory Gene Integrated Score" was further developed from the combination of 18 iCAMP genes in ovarian cancer, which predicted overall survival. Noticeably, as a selective nuclear import protein whose immuno-regulatory function just begins to emerge, karyopherin alpha 2 (KPNA2) is uniformly up-regulated across cancer types. For the first time, the cancer-specific up-regulation of KPNA2 and its clinical significance were verified by tissue microarray analysis in colon and head-neck cancers.

CONCLUSION

This work defines an inflammatory signature shared by seven epithelial cancer types and KPNA2 as a consistently up-regulated protein in cancer. Identification of iCAMP may not only serve as a novel biomarker for prognostication and individualized treatment of cancer, but also have significant biological implications.

Methylation markers of early-stage non-small cell lung cancer

Background

Despite of intense research in early cancer detection, there is a lack of biomarkers for the reliable detection of malignant tumors, including non-small cell lung cancer (NSCLC). DNA methylation changes are common and relatively stable in various types of cancers, and may be used as diagnostic or prognostic biomarkers.

Methods

We performed DNA methylation profiling of samples from 48 patients with stage I NSCLC and 18 matching cancer-free lung samples using microarrays that cover the promoter regions of more than 14,500 genes. We correlated DNA methylation changes with gene expression levels and performed survival analysis.

Results

We observed hypermethylation of 496 CpGs in 379 genes and hypomethylation of 373 CpGs in 335 genes in NSCLC. Compared to adenocarcinoma samples, squamous cell carcinoma samples had 263 CpGs in 223 hypermethylated genes and 513 CpGs in 436 hypomethylated genes. 378 of 869 (43.5%) CpG sites discriminating the NSCLC and control samples showed an inverse correlation between CpG site methylation and gene expression levels. As a result of a survival analysis, we found 10 CpGs in 10 genes, in which the methylation level differs in different survival groups.

Conclusions

We have identified a set of genes with altered methylation in NSCLC and found that a minority of them showed an inverse correlation with gene expression levels. We also found a set of genes that associated with the survival of the patients. These newly-identified marker candidates for the molecular screening of NSCLC will need further analysis in order to determine their clinical utility.

Loss of polymeric immunoglobulin receptor expression is associated with lung tumourigenesis

Polymeric immunoglobulin receptor (pIgR) expression is downregulated in lung cancer, but its implications in lung tumourigenesis remain unknown. We hypothesised that loss of pIgR expression occurs early, and is associated with cell proliferation and poor prognosis. pIgR expression was evaluated by immunohistochemistry in airways of patients with normal mucosa, pre-invasive lesions and invasive lesions, and correlated with clinical outcomes. 16-HBE and A549 cells stably transfected with pIgR were tested for proliferation, apoptosis and cell cycle progression. Immunostaining was strong in normal epithelium, but severely reduced in pre-invasive lesions and most lung cancers. Persistent expression was associated with younger age and adenocarcinoma subtype but not survival. pIgR overexpression significantly reduced A549 and 16-HBE proliferation. Growth inhibition was not due to cell cycle arrest, increased apoptosis or endoplasmic reticulum stress, but we observed altered expression of genes encoding for membrane proteins, including NOTCH3. Interestingly, NOTCH3 expression was inversely correlated with pIgR expression in cell lines and tissues. pIgR expression was lost in most lung cancers and pre-invasive bronchial lesions, suggesting that pIgR downregulation is an early event in lung tumourigenesis. pIgR overexpression in A549 and 16-HBE cells inhibited proliferation. Future investigations are required to determine the mechanisms by which pIgR contributes to cell proliferation.

Involvement of transcription factor activator protein-2alpha in doxazosin-induced HeLa cell apoptosis

AIM

To investigate the pro-apoptotic effects of alpha1-adrenergic inhibitor doxazosin in HeLa cells and the potential involvement of transcription factor activator protein-2alpha (AP-2alpha) in doxazosin-induced apoptosis.

METHODS

The HeLa cells were exposed to various concentrations of doxazosin for 16 h. Apoptosis was detected using a DNA fragmentation assay, Hoechst 33258 staining, and flow cytometric analysis. The expression of AP-2alpha and caspase-3 was detected by relative quantitative RT-PCR and Western blot assays, respectively. After the respective transfections of the HeLa cells with AP-2alpha overexpressing constructs and an antisense oligonucleotide against AP-2alpha, apoptosis was assessed by flow cytometric analysis, and the expression of AP-2alpha and caspase-3 was detected by relative quantitative RT-PCR and Western blot assays. The colorimetric assay was performed to detect the caspase-3 activity.

RESULTS

Treatment with various concentrations of doxazosin for 16 h increased the apoptotic rate and total cell death rate of the HeLa cells in a dose-dependent manner and upregulated the expression of AP-2alpha and caspase-3 in a dose-dependent manner. A dose-dependent increase was observed in the caspase-3 activity. Overexpressing AP-2alpha led to the increased rate of doxazosin-induced apoptosis and the total cell death, whereas doxazosin-induced apoptosis and the total cell death in HeLa cells decreased by antisense AP-2alpha. Furthermore, overexpressing AP-2alpha increased the expression and activity of caspase-3, whereas antisense AP-2alpha in part abolished the increased effects of doxazosin on caspase-3 expression and activity.

CONCLUSION

Doxazosin induces apoptosis in HeLa cells in a dose-dependent manner, and transcription factor AP-2alpha is functionally involved in doxazosin-induced HeLa cell apoptosis.

The polymeric immunoglobulin receptor: bridging innate and adaptive immune responses at mucosal surfaces

Secretory antibodies of the immunoglobulin A (IgA) class form the first line of antigen-specific immune protection against inhaled, ingested, and sexually transmitted pathogens and antigens at mucosal surfaces. Epithelial transcytosis of polymeric IgA (pIgA) is mediated by the polymeric immunoglobulin receptor (pIgR). At the apical surface, the extracellular ligand-binding region of pIgR, known as secretory component (SC), is cleaved and released in free form or as a component of secretory IgA (SIgA). SC has innate anti-microbial properties, and it protects SIgA from proteolytic degradation. Expression of pIgR is regulated by microbial products through Toll-like receptor signaling and by host factors such as cytokines and hormones. Recent studies of the structure of the extracellular ligand-binding domain of pIgR have revealed mechanisms by which it binds pIgA and other ligands. During transcytosis, pIgA has been shown to neutralize pathogens and antigens within intracellular vesicular compartments. The recent identification of disease-associated polymorphisms in human pIgR near the cleavage site may help to unravel the mystery of how pIgR is cleaved to SC. The identification of novel functions for SC and SIgA has expanded our view of the immunobiology of pIgR, a key component of the mucosal immune system that bridges innate and adaptive immune defense.