Do circulating long non-coding RNAs (lncRNAs) (LincRNA-p21, GAS 5, HOTAIR) predict the treatment response in patients with head and neck cancer treated with chemoradiotherapy?

Long non-coding RNAs (lncRNAs) have been shown to be aberrantly expressed in head and neck cancer (HNC). The aim of the present study was to evaluate plasma levels of three lncRNA molecules (lincRNA-p21, GAS5, and HOTAIR) in the treatment response in HNC patients treated with radical chemoradiotherapy (CRT). Forty-one patients with HNC were enrolled in the study. Most of the patients had nasopharyngeal carcinoma (n = 27, 65.9 %) and locally advanced disease. Blood was drawn at baseline and treatment evaluation 4.5 months after therapy. lncRNAs in plasma were measured by semiquantitative PCR. Treatment response was evaluated according to clinical examination, RECIST and PERCIST criteria based on magnetic resonance imaging (MRI), and positron emission tomography with computed tomography (PET/CT) findings. Complete response (CR) rates were 73.2, 36.6, and 50 % for clinical investigation, PET/CT-, or MRI-based response evaluation, respectively. Predictive value of lncRNAs was investigated in patients with CR vs. those with partial response (PR)/progressive disease (PD). We found that post-treatment GAS5 levels in patients with PR/PD were significantly higher compared with patients with CR based on clinical investigation (p = 0.01). Receiver operator characteristic (ROC) analysis showed that at a cutoff value of 0.3 of GAS5, sensitivity and specificity for clinical tumor response were 82 and 77 %, respectively. Interestingly, pretreatment GAS5 levels were significantly increased in patients with PR/PD compared to those with CR upon MRI-based response evaluation (p = 0.042). In contrast to GAS5, pretreatment or post-treatment lincRNA-p21 and HOTAIR levels were not informative for treatment response. Our results suggest that circulating GAS5 could be a biomarker in predicting treatment response in HNC patients.

Exosomal lncRNA-p21 levels may help to distinguish prostate cancer from benign disease.

Exosomes are membranous vesicles containing various biomolecules including lncRNAs which are involved in cellular communication and are secreted from many cells including cancer cells. In our study, investigated the exosomal GAS5 and lincRNA-p21 lncRNA levels in urine samples from 30 patients with prostate cancer (PCa) and 49 patients with benign prostatic hyperplasia. Quantification of lncRNA molecules was performed by real-time PCR. We observed a significant difference in the exosomal lincRNA-p21 levels between PCa and BPH patients whereas the GAS5 levels did not reveal a difference. Our data suggest that the discriminative potential of exosomal lincRNA-p21 levels may help to improve the diagnostic prediction of the malignant state for patients with PCa.

LncRNAs and neoplasia.

Long noncoding RNAs are emerging as new mediators of tumorigenesis by virtue of their various functions and their capacity to induce different mechanisms as a result of their wide spectrum of interactions. They play critical roles in a broad range of cellular processes including regulation of gene expression, imprinting, chromatin modification, transcription and posttranslational processing. Expression and activity of lncRNAs are deregulated in several types of human cancer. Impairment of lncRNA activity may affect key components of the cellular gene regulatory networks and is associated with deregulation of a large number of cellular oncogenic pathways. LncRNAs are also being evaluated as diagnostic and prognostic biomarkers and may provide targets for potential therapeutic applications. An improved understanding of the roles played by lncRNAs in cancer will lead to more effective therapeutic strategies. In this review we summarize the current knowledge on lncRNAs and their function as mediators of tumor development.

Long non-coding RNAs with low expression levels in cells are enriched in secreted exosomes.

Long non-coding RNAs (lncRNAs) are involved in regulating chromatin modifications, gene transcription, mRNA translation, and protein function. We recently reported a high variation in the basal expression levels of a panel of lncRNAs in HeLa and MCF-7 cells and their differential response to DNA damage induction. Here, we hypothesized that lncRNA molecules with different cellular expression may have a differential abundance in secreted exosomes, and their exosome levels would reflect cellular response to DNA damage. MALAT1, HOTAIR, lincRNA-p21, GAS5, TUG1, CCND1-ncRNA in exosomes secreted from cultured cells were characterized. A different expression pattern of lncRNAs in exosomes was seen compared to cells. RNA molecules with relative low expression levels (lincRNA-p21, HOTAIR, ncRNA-CCND1) were highly enriched in exosomes. TUG1 and GAS5 levels were moderately elevated in exosomes, whereas MALAT1--which was the most abundant molecule in cells--was present at levels comparable to its cellular levels. lincRNA-p21 and ncRNA-CCND1 were the main molecules; exosome levels of them best reflect the change of their cellular levels upon exposure of the cells to bleomycin-induced DNA damage. In conclusion, we provide evidence that lncRNAs have a differential abundance in exosomes, indicating a selective loading.

Investigation of circulating lncRNAs in B-cell neoplasms.

Long non-coding RNAs (lncRNA) which are longer than 200 base pairs in length, play an important role in cellular machinery. Chronic lymphocytic leukemia (CLL) and multiple myeloma (MM) are neoplasms of B-cells. In our study we aimed to investigate circulating lncRNA levels of CLL and MM patients. For this purpose we selected 5 candidate lncRNAs (TUG1, LincRNA-p21, MALAT1, HOTAIR, and GAS5) where the first two are regulated by p53. Analyses were performed by real-time PCR using cDNA synthesized from plasma RNAs. In both disease groups differential levels of plasma lncRNAs were observed. LincRNA-p21 was the only molecule displaying significant changes in the CLL group while all remaining lncRNAs showed significant differences in the MM group. In the MM group only TUG1 showed higher levels than the healthy volunteers. In conclusion, the expression levels of the candidate lncRNA molecules display a general trend for tissue- and disease-specific expression which can provide important potential biomarkers specific to the particular disease type. However, further studies are necessary to elucidate their involvement in disease development and progression.

Differential expression of long non-coding RNAs during genotoxic stress-induced apoptosis in HeLa and MCF-7 cells.

Long non-coding RNAs (lncRNAs) are emerging as new players in cancer as they are implicated in diverse biological processes and aberrantly expressed in a variety of human cancers. No data are available on their function under genotoxic stress-induced apoptosis. In this work, we assessed the behavior of some candidate lncRNAs (HOTAIR, MALAT1, TUG1, lincRNA-p21, GAS5, MEG3, PANDA, UCA1, ANRIL, and CCND1) during DNA damage-induced cell death in HeLa and caspase-3-deficient MCF-7 cells using bleomycin (BLM) and γ-radiation to induce DNA damage. Cells were incubated in the presence of BLM for 24 h or irradiated. Apoptosis was analyzed by measurement of oligonucleosomal fragmentation of nuclear DNA. Our results reveal that basal RNA expression levels as well as the changes in the lncRNA expression rates during genotoxic stress-induced apoptosis were cell-type and/or DNA-damaging agent-specific. Generally, we found that some of the RNA molecules (HOTAIR and MALAT1) are down-regulated while many of them (lincRNA-p21, GAS5, MEG3, ANRIL, and ncRNA-CCND1) are up-regulated and some others (TUG1, UCA1, and PANDA) not affected. The decline in the expression of HOTAIR (approx. twofold, p < 0.01) and MALAT1 (approx 1.6-fold, p < 0.01) was clearly evident in BLM-treated HeLa and MCF cells (only HOTAIR, fivefold, p < 0.01). For lincRNA-p21, ncRNA-CCND1, and MEG3, a similar up-regulation pattern was obvious in both cell lines where the increase was generally more pronounced in BLM-treated cells. Interestingly, the induction of ANRIL and GAS5 was mainly restricted to irradiated cells. In conclusion, our findings reveal a differential regulation of individual lncRNAs during genotoxic stress-induced apoptosis.

Analysis of p53 tumor suppressor pathway genes in chronic lymphocytic leukemia.

The p53 tumor suppressor gene plays an important role in preventing tumor development. The p53 protein interacts with other p53 signal pathway members to control cell proliferation. In this study, expression of the p53, Human homolog of murine Double Minute 2 (HDM2), p14Alternating Reading Frame (ARF), Zinc Finger and BTB domain containing 7A (ZBTB7A), and B-Cell Lymphoma 6 (BCL6) genes was quantitatively investigated by real-time polymerase chain reaction (PCR) in the peripheral blood of patients with chronic lymphocytic leukemia (CLL) and healthy controls. Plasma fibronectin levels were determined by enzyme-linked immunosorbent assay. Expression of the p53, p14, and HDM2 genes were significantly higher in the patients. However, ZBTB7A and BCL6 gene expression was not detectable in both groups. A positive correlation between p14ARF and HDM2 expression and a negative correlation between p53 and p14ARF expression was observed. Expression of the p14ARF and HDM2 genes were inversely correlated in the control group. Neither HDM2 nor p14ARF gene expression was correlated with p53 expression. The p53 gene was also analyzed for the presence of mutations. A splice-site mutation was found in a single patient. Our findings indicate that expression of the p53, p14ARF, and HDM2 genes are associated with CLL. Elucidation of the mutual interactions at the protein level warrants further studies.

Investigation of the miR16-1 (C > T) + 7 Substitution in Seven Different Types of Cancer from Three Ethnic Groups.

Background. MicroRNAs are a type of small noncoding RNA molecules that have been shown to control gene expression in eukaryotes. Aberrant expression and alteration of miRNAs may be responsible for human diseases including cancer. An miR16-1 (C > T) + 7 gene mutation has been previously found in familial chronic lymphocytic leukemia patients, one of which reported a family history of breast cancer. miR16-1 regulates the expression of bcl-2, which is important in retinoblastoma, and is located in a genomic region that is frequently lost in nasopharyngeal and hepatocellular carcinomas (HCCs). Therefore, miR16-1 may be potentially important in the etiology of several solid tumors. To understand the power of the miR16-1 (C > T) + 7 mutation as a prognostic and diagnostic risk factor, we investigated the mutation in patients with seven different types of cancer including 188 with breast, 102 with ovarian, and 22 nasopharyngeal carcinomas, 96 HCC, 872 chronic myeloid leukemia (CML), 39 chronic lymphocytic leukemia (CLL), and 46 retinoblastoma cases from three different ethnic groups and of hereditary and sporadic etiology. Methods. 5'Nuclease TaqMan SNP genotyping assay was used to detect the miR16-1 gene C > T substitution. Results. The miR16-1 (C > T) + 7 substitution was not detected in any of the groups studied. Conclusions. Considering the large scale of our study, the representation of different ethnicities and levels of hereditary risk, we conclude that the miR-16-1 (C > T) + 7 mutation is not a good diagnostic or prognostic indicator of risk for the cancers tested.

p53 codon 72 polymorphism and HPV status in lung cancer.

BACKGROUND: Several risk factors, both environmental and genetic, have been associated with the pathogenesis of lung cancer. A common polymorphism at codon 72 of exon 4 of the p53 gene encoding either an arginine or proline has been shown to confer susceptibility to the development of different human malignancies. This polymorphism affects proteolytic degradation of p53 promoted by the HPV-E6 protein and represents a risk factor for human-papillomavirus-induced carcinogenesis. MATERIAL/METHODS: A total of 65 patients with lung cancer were recruited into the study and 87 healthy subjects were used as the control group. The codon 72 polymorphism was determined by the PCR-RFLP method. Presence of human papillomavirus DNA was analyzed by polymerase chain reaction using MY09 and MY11 consensus primers and hybridization with HPV16 and HPV18 specific probes. RESULTS: The frequencies of the Arg and Pro alleles were 68.46% and 31.54% in lung cancer patients and 55.7% and 44.3% in the healthy control subjects, respectively. These differences were statistically significant. Human papillomavirus DNA was detected in the blood circulation of only 1 patient. CONCLUSIONS: Our results suggest that the Arg/Arg genotype may represent a potential risk factor for the development of lung cancer independent of the HPV infection.