MicroRNAs and glioblastoma: roles in core signalling pathways and potential clinical implications

MicroRNAs (miRNAs) are endogenously expressed small non-coding RNAs that act as post-transcriptional regulators of gene expression. Dysregulation of these molecules has been indicated in the development of many cancers. Altered expression levels of several miRNAs were identified also in glioblastoma. It was repeatedly found that miRNAs are involved in important signalling pathways, which play roles in crucial cellular processes, such as proliferation, apoptosis, cell cycle regulation, invasion, angiogenesis and stem cell behaviour. Therefore, miRNAs represent promising therapeutic targets in glioblastoma. In this review, we summarize the current knowledge about miRNAs significance in glioblastoma, with special focus on their involvement in core signalling pathways, their roles in drug resistance and potential clinical implications.

MiR-195, miR-196b, miR-181c, miR-21 expression levels and O-6-methylguanine-DNA methyltransferase methylation status are associated with clinical outcome in glioblastoma patients

Glioblastoma multiforme (GBM) is the most frequently occurring primary malignant brain tumor; patients with GBM often have a very poor prognosis and differing responses to treatment. Therefore, it is very important to find new biomarkers that can predict clinical outcomes and help in treatment decisions. MicroRNAs are small, non-coding RNAs that function as post-transcriptional regulators of gene expression and play a key role in the pathogenesis of GBM. In a group of 38 patients with primary GBM, we analyzed the expression of eight microRNAs (miR-21, miR-128a, miR-181c, miR-195, miR-196a, miR-196b, miR-221, and miR-222). In addition, we examined the methylation status of O-6-methylguanine-DNA methyltransferase (MGMT) promoter by high-resolution melting analysis, as this has been shown to be a predictive marker in GBM. MGMT methylation status correlated with progression-free survival (P = 0.0201; log-rank test) as well as with overall survival (P = 0.0054; log-rank test). MiR-195 (P = 0.0124; log-rank test) and miR-196b (P = 0.0492; log-rank test) positively correlated with overall survival. Evaluation of miR-181c in combination with miR-21 predicted time to progression within 6 months of diagnosis with 92% sensitivity and 81% specificity (P < 0.0001). Our data confirmed that the methylation status of MGMT but also miR-21, miR-181c, miR-195, and miR-196b to be associated with survival of GBM patients. Above all, we suggest that the combination of miR-181c and miR-21 could be a very sensitive and specific test to identify patients at high risk of early progression after surgery.

Assessing the invasiveness of NOTES perforated viscus repair: a comparative study of NOTES and laparoscopy

BACKGROUND

Natural orifice transluminal endoscopic surgery (NOTES) repair of perforated peptic ulcers may decrease surgical invasiveness and improve patient outcomes.

METHODS

Full thickness gastrotomy was created laparoscopically in swine followed by soilage time. Repair proceeded with a laparoscopic (n = 14) or the NOTES (n = 14) approach. For NOTES repair, the omentum was endoscopically pulled into the gastric lumen and clipped. Intraoperative and postoperative parameters were recorded, including arterial blood gas (ABG) analysis and serum samples for white blood cell (WBC), TNF-α, IL-1, and IL-6 analysis.

RESULTS

Twenty-four of 28 animals thrived to study completion. NOTES repair could not be accomplished in one animal. At necropsy, all repairs were intact. Blood pressure was equivalent between groups. Pulse examined during the last 30 min of each procedure revealed a slightly higher mean pulse in the animals undergoing NOTES procedures (NOTES, 102 ± 28; laparoscopy, 83 ± 24). ABG obtained at the conclusion of the procedure revealed a pH of 7.47 in NOTES animals and 7.43 in the laparoscopy animals (p = 0.06), a change from baseline in both groups. The final pCO(2) was lower in the NOTES group (NOTES, 40.62; laparoscopy, 47.49, p = 0.03). WBC counts were comparable on postoperative day (POD) 1 (NOTES, 21.1; laparoscopy, 19.0; p = 0.49). Mean TNF-α serum levels were equivalent at all time points between groups; however, TNF-α varied significantly from baseline to POD 7 (p = 0.002).

CONCLUSION

NOTES omental repair appears comparable to that of laparoscopy. The lower arterial pCO(2) at the conclusion of the NOTES procedure may be advantageous in critically ill patients.

Imbalance in T-cell and cytokine profiles in patients with relapsing-remitting multiple sclerosis

Multiple sclerosis (MS) is characterized by autoimmune attack leading to demyelination of the white matter in the central nervous system with devastating clinical consequences. Several immune-mediated destruction mechanisms were previously proposed including different T-cell subsets but complex view on immune system function in patients with MS is missing. In the present study, T-lymphocyte populations and pro-inflammatory as well as suppressive cytokine profiles were evaluated in detail in previously untreated patients with relapsing-remitting MS (RRMS). CD4(+) and CD8(+) naïve, central memory (Tcm), effector memory (Tem), terminal effector memory (Ttem), CD4(+) regulatory T-cells (Treg) and CD8(+) T-suppressor cells (Ts) were analysed using flow cytometry, and levels of ten plasma cytokines were determined using fluorescent bead-based immunoassay. We evaluated two groups of RRMS with minor (n=33) and major (n=25) clinical impairment and compared them with healthy controls (n=40) in order to detect any correlation between severity of MS clinical symptoms and immune disturbances. Significant differences were noted in CD4(+)CD45RA(+)CCR7(+) naïve T-cells, CD4(+)CD45RO(+)CCR7(-) and CD8(+)CD45RO(+)CCR7(-) Tem cells, while no differences were recognized in Tcm, Ttem, Treg and Ts cells in RRMS patients. Nine out of ten studied cytokines were disturbed in plasma samples of patients with RRMS. In conclusion, we demonstrate complex immune dysbalances in untreated MS patients.

Expression of immune-modulatory molecules HLA-G and HLA-E by tumor cells in glioblastomas: an unexpected prognostic significance?

The role of nonclassical human leukocyte antigens G and E (HLA-G and HLA-E) was originally thought to be restricted to the protection of the fetus from a maternal allorecognition. Now it is known that HLA-G and HLA-E exert multiple immunoregulatory functions. A prognostic significance of the expression of HLA-G and HLA-E by neoplastic cells in glioblastoma is not well characterized. In this study, we evaluated the expression of HLA-G and HLA-E by neoplastic cells in 39 cases of glioblastoma. We found the production of HLA-G and HLA in a majority of cases. There was an unexpected positive correlation between the expression of HLA-E and length of survival. We speculate that the expression of this molecule by neoplastic cells may represent a coincidental selective pro-host advantage related to better response to subsequent therapeutic modalities. Mechanisms of glioblastoma cell pathophysiology and mechanisms of responses to therapeutic interventions in respect to the expression of these molecules deserves further study.

Generation of myeloma-specific T cells using dendritic cells loaded with MUC1- and hTERT- drived nonapeptides or myeloma cell apoptotic bodies

Dendritic cells are able to induce anti-tumor immune responses by presenting tumor-specific antigens to T-lymphocytes. Various tumor-associated antigens have been studied in multiple myeloma in an effort to find a strong antigen capable of generating clinically meaningful responses in vaccinated patients. The aim of our study was to generate myeloma-specific cytotoxic T lymphocytes in vitro using dendritic cells loaded with peptide antigens or apoptotic bodies. Peripheral blood mononuclear cells from HLA-A2+ healthy donors were used for isolation and culture of dendritic cells (DCs) and T lymphocytes. DCs were loaded with hTERT- and MUC1-derived nonapeptides or apoptotic bodies from myeloma cells. Repeated stimulation of T lymphocytes led to their activation characterized by interferon-gamma production. Activated T lymphocytes were separated immunomagnetically and expanded in vitro. Specific cytotoxicity of the expanded T lymphocytes was tested against a myeloma cell line. There was evidence of cytotoxicity for all three types of antigens used for T lymphocyte priming and expansion. No statistically significant differences were observed in T lymphocyte cytotoxicity for any of the antigens. We present a method for the priming and expansion of myeloma-specific T lymphocytes using dendritic cells loaded with different types of tumor antigens. Cytotoxic T lymphocytes and/or activated dendritic cells generated by the described methods can be applied for cellular immunotherapy against multiple myeloma and other malignancies.

MicroRNA-181 family predicts response to concomitant chemoradiotherapy with temozolomide in glioblastoma patients

MicroRNAs are endogenously expressed regulatory noncoding RNAs. Previous studies showed altered expression levels of several microRNAs in glioblastomas. In this study, we examined the expression levels of selected microRNAs in 22 primary glioblastomas and six specimens of adult brain tissue by real-time PCR method. In addition, we examined methylation status of MGMT promoter by methylation-specific real-time PCR, as this has been shown to be a predictive marker in glioblastomas. MGMT methylation status was not correlated with response to concomitant chemoradiotherapy with temozolomide (RT/TMZ). MiR-221 (p=0.016), miR-222 (p=0.038), miR-181b (p=0.036), miR-181c (p=0.043) and miR-128a (p=0.001) were significantly down-regulated in glioblastomas. The most significant change was observed for up-regulation in miR-21 expression in glioblastomas (p<0.001). MiR-181b and miR-181c were significantly down-regulated in patients who responded to RT/TMZ (p=0.016; p=0.047, respectively) in comparison to patients with progredient disease. Our data indicate for the first time that expression levels of miR-181b and miR-181c could serve as a predictive marker of response to RT/TMZ therapy in glioblastoma patients.

Expression of miRNA-106b in conventional renal cell carcinoma is a potential marker for prediction of early metastasis after nephrectomy

BACKGROUND

MicroRNAs are endogenously expressed regulatory noncoding RNAs. Previous studies have shown altered expression levels of several microRNAs in renal cell carcinoma.

METHODS

We examined the expression levels of selected microRNAs in 38 samples of conventional renal cell carcinoma (RCC) and 10 samples of non-tumoral renal parenchyma using TaqMan real-time PCR method.

RESULTS

The expression levels of miRNA-155 (p < 0.0001), miRNA-210 (p < 0.0001), miRNA-106a (p < 0.0001) and miRNA-106b (p < 0.0001) were significantly over-expressed in tumor tissue, whereas the expression of miRNA-141 (p < 0.0001) and miRNA-200c (p < 0.0001) were significantly decreased in RCC samples. There were no significant differences between expression levels of miRNA-182 and miRNA-200b in tumor samples and renal parenchyma. Our data suggest that expression levels of miRNA-106b are significantly lower in tumors of patients who developed metastasis (p = 0.030) and miR-106b is a potential predictive marker of early metastasis after nephrectomy in RCC patients (long-rank p = 0.032).

CONCLUSIONS

We have confirmed previous observations obtained by miRNA microarray analysis using standardized real-time PCR method. For the first time, we have identified a prognostic significance of miRNA-106b, which, after validation on a larger group of patients, maybe useful as a promising biomarker in patients with RCC.

Production of immune-modulatory nonclassical molecules HLA-G and HLA-E by tumor infiltrating ameboid microglia/macrophages in glioblastomas: a role in innate immunity?

The possible role of immune-modulatory nonclassical molecules HLA-G and HLA-E in an anti-tumoral response and development of glioblastoma is not well characterized. In this study, we evaluated an expression of HLA-G and HLA-E by activated tumor infiltrating microglia/macrophages. We found production of HLA-G and HLA-E by tumor infiltrating activated microglia/macrophages in a majority of glioblastomas. We speculate that the expression of these molecules by activated microglia/CNS macrophages plays a role in the anti-tumoral immunity in the development of glioblastoma. Mechanisms of microglia-glioblastoma cell interactions with respect to the expression of these molecules deserves further study.

Individual myeloma-specific T-cell clones eliminate tumour cells and correlate with clinical outcomes in patients with multiple myeloma

Despite novel treatment strategies, multiple myeloma (MM) remains an incurable disease with low immunogenicity and multiple immune defects. We developed an ex vivo strategy for inducing myeloma-specific cytotoxic T lymphocytes (CTLs) and demonstrate the possibility of identification and long-term in vivo monitoring of individual myeloma-specific T-cell clones using the most sensitive clonotypic assay that is able to detect low frequencies of T-cell clones (1 clonotypic cell in 10(6) cells). Ten patients with MM were examined for the presence of tumour-reactive T cells using dendritic cells loaded with autologous tumour cells. All patients had detectable myeloma-reactive T cells in vitro. Expanded myeloma-reactive T cells demonstrated specific cytotoxic effects against autologous tumour cells in vitro (median 39.6% at an effector:target ratio of 40:1). The clonality of myeloma-specific T cells was studied with a clonotypic assay, which demonstrated both oligoclonal and monoclonal populations of myeloma-specific T cells. CD8(+) CTLs were the most immunodominant myeloma-specific T-cell clones and clinical responses were closely associated with the in vivo expansion and long-term persistence of individual CD8(+) T-cell clones, usually at very low frequencies (10(-3)-10(-6)). We conclude that the clonotypic assay is the most sensitive tool for immunomonitoring of low-frequency T cells.

microRNA-342, microRNA-191 and microRNA-510 are differentially expressed in T regulatory cells of type 1 diabetic patients

Regulatory T cells (Tregs) are critical regulators of autoimmune diseases, including type 1 diabetes mellitus. It is hypothesised that Tregs' function can be influenced by changes in the expression of specific microRNAs (miRNAs). Thus, we performed miRNAs profiling in a population of Tregs separated from peripheral blood of five type 1 diabetic patients and six healthy donors. For more detailed molecular characterisation of Tregs, we additionally compared miRNAs expression profiles of Tregs and conventional T cells. Tregs were isolated according to CD3+, CD4+, CD25(hi)+ and CD127- by flow cytometry, and miRNA expression profiling was performed using TaqMan Array Human MicroRNA Panel-1 (384-well low density array). In Tregs of diabetic patients we found significantly increased expression of miRNA-510 (p=0.05) and decreased expression of both miRNA-342 (p<0.0001) and miRNA-191 (p=0.0079). When comparing Tregs and T cells, we revealed that Tregs had significant higher expression of miRNA-146a and lower expression of eight specific miRNAs (20b, 31, 99a, 100, 125b, 151, 335, and 365). To our knowledge, this is the first study demonstrating changes in miRNA expression profiles occurring in Tregs of T1D patients and a miRNAs signature of adult Tregs.

Expression pattern of HLA class I antigens in renal cell carcinoma and primary cell line cultures: methodological implications for immunotherapy

BACKGROUND

Renal cell carcinomas have developed various strategies to escape immune cell recognition, including down-regulation or loss of classic HLA class I antigens (A, B, C) and aberrant expression of non-classic HLA class I antigens (G, E). In this study both classic and non-classic HLA class I antigens were tested in tumor specimens and established primary cell cultures derived from renal cell carcinoma patients.

MATERIAL/METHODS

HLA class I antigens were evaluated by immunohistochemical staining and the intensity of cytoplasmic staining was measured semiquantitatively. Renal tumor tissue obtained from nephrectomy was used for the explant culture. MTT assay was performed to test the chemoresistance of primary cell line cultures to common cytostatics.

RESULTS

HLA-G and HLA-E were found in 62% and 100% of the analyzed tumor samples, respectively. Markedly higher levels of the non-classic HLA-G and -E antigens compared with the classic HLA-A, -B, and -C antigens were observed. The cells of the control renal tissues were HLA-A, -B, -C, and -E positive and HLA-G negative. Cell line cultures were successfully established in 85% of the renal cell carcinoma specimens. No or minimal changes in classic HLA-A, B, and C antigen staining were observed during cultivation of the primary cell line cultures. No correlation between HLA class I antigen expression and chemoresistance, histopathological stage, or nuclear grade was found.

CONCLUSIONS

These findings suggest that primary cell line cultures derived from surgical specimens of renal cell carcinomas are a feasible model for immunotherapy research through their high cultivation potential.

MicroRNAs in colorectal cancer: translation of molecular biology into clinical application

MicroRNAs (miRNAs) are small non-coding RNAs 18-25 nucleotides in length that downregulate gene expression during various crucial cell processes such as apoptosis, differentiation and development. Changes in the expression profiles of miRNAs have been observed in a variety of human tumors, including colorectal cancer (CRC). Functional studies indicate that miRNAs act as tumor suppressors and oncogenes. These findings significantly extend Vogelstein's model of CRC pathogenesis and have shown great potential for miRNAs as a novel class of therapeutic targets. Several investigations have also described the ability of miRNA expression profiles to predict prognosis and response to selected treatments in CRC patients, and support diagnosis of CRC among cancer of unknown primary site. miRNAs' occurrence has been repeatedly observed also in serum and plasma, and miRNAs as novel minimally invasive biomarkers have indicated reasonable sensitivity for CRC detection and compare favorably with the fecal occult blood test. In this review, we summarize the knowledge regarding miRNAs' functioning in CRC while emphasizing their significance in pathogenetic signaling pathways and their potential to serve as disease biomarkers and novel therapeutic targets.

Significant overexpression of Hsp110 gene during colorectal cancer progression

Colorectal cancer (CRC) is one of the most frequent malignant diseases in the world. Metastatic spread of the cancer to the lymph nodes is a crucial factor for progression and therapeutic management of the disease. We analysed gene expression profiles of CRC patiens by low-density cancer-focused oligonucleotide microarrays to identify new predictive markers of the extent of the disease and for better understanding of CRC progression. Relative expression levels of 440 genes known to be involved in cancer biology were obtained by low-density oligonucleotide microarrays from 20 tumor samples. Statistical analysis of gene expression data identified 3 genes (HSP110, HYOU1 and TCTP) significantly up-regulated in primary tumors of patients who developed lymph node metastasis. We have shown, for the first time, that up-regulation HSP110 and HYOU1 expression is associated with lymph node involvement in CRC. We validated the differences in HSP110 expression in an independent group of 30 patients of all clinical stages by real-time PCR. We identified significant up-regulation of HSP110 expression in colorectal tumors compared to adjacent non-tumoral tissue (p<0.0003). We observed significant differences of HSP110 gene expression between metastatic and localized disease (p=0.031) and negative trend of HSP110 gene expression and overall survival of CRC patients. We suggest that HSP110 gene is a promising molecular predictor in CRC.

MicroRNA involvement in glioblastoma pathogenesis

MicroRNAs are endogenously expressed regulatory noncoding RNAs. Altered expression levels of several microRNAs have been observed in glioblastomas. Functions and direct mRNA targets for these microRNAs have been relatively well studied over the last years. According to these data, it is now evident, that impairment of microRNA regulatory network is one of the key mechanisms in glioblastoma pathogenesis. MicroRNA deregulation is involved in processes such as cell proliferation, apoptosis, cell cycle regulation, invasion, glioma stem cell behavior, and angiogenesis. In this review, we summarize the current knowledge of miRNA functions in glioblastoma with an emphasis on its significance in glioblastoma oncogenic signaling and its potential to serve as a disease biomarker and a novel therapeutic target in oncology.