Multiple Isoforms of ANRIL in Melanoma Cells: Structural Complexity Suggests Variations in Processing

The long non-coding RNA ANRIL, antisense to the CDKN2B locus, is transcribed from a gene that encompasses multiple disease-associated polymorphisms. Despite the identification of multiple isoforms of ANRIL, expression of certain transcripts has been found to be tissue-specific and the characterisation of ANRIL transcripts remains incomplete. Several functions have been associated with ANRIL. In our judgement, studies on ANRIL functionality are premature pending a more complete appreciation of the profusion of isoforms. We found differential expression of ANRIL exons, which indicates that multiple isoforms exist in melanoma cells. In addition to linear isoforms, we identified circular forms of ANRIL (circANRIL). Further characterisation of circANRIL in two patient-derived metastatic melanoma cell lines (NZM7 and NZM37) revealed the existence of a rich assortment of circular isoforms. Moreover, in the two melanoma cell lines investigated, the complements of circANRIL isoforms were almost completely different. Novel exons were also discovered. We also found the family of linear ANRIL was enriched in the nucleus, whilst the circular isoforms were enriched in the cytoplasm and they differed markedly in stability. With respect to the variable processing of circANRIL species, bioinformatic analysis indicated that intronic Arthrobacter luteus (Alu) restriction endonuclease inverted repeats and exon skipping were not involved in selection of back-spliced exon junctions. Based on our findings, we hypothesise that “ANRIL” has wholly distinct dual sets of functions in melanoma. This reveals the dynamic nature of the locus and constitutes a basis for investigating the functions of ANRIL in melanoma.Peer reviewe

Acute effects of hydroxychloroquine prophylaxis for COVID-19 in health care professionals – An online survey

Hydroxychloroquine, an antimalarial, is being used worldwide for prophylaxis and treatment of Corona virus disease-19 (COVID-19). Though the drug is commonly used in many chronic inflammatory diseases for protracted periods, its safety in the new indication is still under scrutiny. Therefore, this institute based study sought to assess the acute adverse effects of hydroxychloroquine among in-house health care professionals who were taking the drug for COVID-19 prophylaxis. A questionnaire seeking information on the use of the drug was prepared and disseminated electronically to the target population. The responses were also received electronically and analysed. The participants (n=54) had taken prophylaxis for 1-7 weeks. The most common adverse effects in the cohort were nausea (02) and skin rash (02). The total number of adverse effects reported by the participants was 08. One incidence each of gastric upset (01), dizziness (01), pain abdomen (01), and chest tightness (01) was reported. None of the adverse effects were serious. Our study indicates that the prophylactic weekly single dose of hydroxychloroquine is not associated with any serious adverse effects within 1-7 weeks of initiation. Elucidation of the long term and chronic adverse effects, if any, requires further studies

Circular RNAs: Potential Applications as Therapeutic Targets and Biomarkers in Breast Cancer

Circular RNAs (circRNAs) are a class of non-coding RNAs that form a covalently closed loop. A number of functions and mechanisms of action for circRNAs have been reported, including as miRNA sponge, exerting transcriptional and translational regulation, interacting with proteins, and coding for peptides. CircRNA dysregulation has also been implicated in many cancers, such as breast cancer. Their relatively high stability and presence in bodily fluids makes cancer-associated circRNAs promising candidates as a new biomarker. In this review, we summarize the research undertaken on circRNAs associated with breast cancer, discuss circRNAs as biomarkers, and present circRNA-based therapeutic approaches

Methods used for noncoding RNAs analysis

Noncoding RNAs are RNA species that do not encode for proteins, and the majority of the human transcriptome is dominated by ncRNA. Recent extensive genomic and transcriptomic analyses have identified many different classes and sizes of ncRNA. They are now understood to be critical to the overall functioning, growth, development, and differentiation of cells. Differential expression and tissue specificity of many ncRNAs have been reported in normal development and disease states including cancer. Lack of functional ncRNAs may also lead to cancer progression. Therefore noncoding transcripts as biomarkers may be used in either predictive or prognostic ways. As such, over the past 15 years they have emerged as key biomarkers in cancer pathology, relating to both early detection and molecular subtyping. Due to important functional roles of ncRNAs in various cancers, the requirement for technologies used in the field is rapidly increasing. This chapter classifies ncRNAs based on their sizes, and describes methods applied for the identification and characterization of ncRNAs. It outlines key methods used for the purification of good quality RNA, various detection methods, analysis of gene expression as well as techniques that can applied for functional characterization of ncRNA. It also highlights critical steps and options to provide a general guide for ncRNA analysis

SOX2OT Long Noncoding RNA Is Regulated by the UPR in Oestrogen Receptor-Positive Breast Cancer

Endoplasmic reticulum (ENR) stress perturbs cell homeostasis and induces the unfolded protein response (UPR). In breast cancer, this process is activated by oestrogen deprivation and is associated with tamoxifen resistance. We present evidence that the transcription factor SOX2 and the long noncoding RNA SOX2 overlapping transcript (SOX2OT) are upregulated in oestrogen receptor-positive (ER+) breast cancer and in response to oestrogen deprivation. We examined the effect of the UPR on SOX2 and SOX2OT expression and the effect of SOX2OT on UPR pathways in breast cancer cell lines. The induction of the UPR by thapsigargin or glucose deprivation upregulates SOX2OT expression. This upregulation is also shown with the anti-oestrogen 4OH-tamoxifen and mTOR inhibitor everolimus in ER + breast cancer cells that are sensitive to oestrogen deprivation or everolimus treatment. SOX2OT overexpression decreased BiP and PERK expression. This effect of SOX2OT overexpression was confirmed on BiP and PERK pathway by q-PCR. Our results show that a long noncoding RNA regulates the UPR and evince a new function of SOX2OT as a participant of ENR stress reprogramming of breast cancer cells

Endocrine Therapy of Estrogen Receptor-Positive Breast Cancer Cells: Early Differential Effects on Stem Cell Markers

IntroductionEndocrine therapy of breast cancer, which either deprives cancer tissue of estrogen or prevents estrogen pathway signaling, is the most common treatment after surgery and radiotherapy. We have previously shown for the estrogen-responsive MCF-7 cell line that exposure to tamoxifen, or deprivation of estrogen, leads initially to inhibition of cell proliferation, followed after several months by the emergence of resistant sub-lines that are phenotypically different from the parental line. We examined the early responses of MCF-7 cells following either exposure to 4-hydroxytamoxifen or deprivation of estrogen for periods of 2 days–4 weeks.MethodsEndocrine-sensitive or -resistant breast cancer cell lines were used to examine the expression of the stem cell gene SOX2, and the Wnt effector genes AXIN2 and DKK1 using quantitative PCR analysis. Breast cancer cell lines were used to assess the anti-proliferative effects (as determined by IC50 values) of Wnt pathway inhibitors LGK974 and IWP-2.ResultsHormone therapy led to time-dependent increases of up to 10-fold in SOX2 expression, up to threefold in expression of the Wnt target genes AXIN2 and DKK1, and variable changes in NANOG and OCT4 expression. The cells also showed increased mammosphere formation and increased CD24 surface protein expression. Some but not all hormone-resistant MCF-7 sub-lines, emerging after long-term hormonal stress, showed up to 50-fold increases in SOX2 expression and smaller increases in AXIN2 and DKK1 expression. However, the increase in Wnt target gene expression was not accompanied by an increase in sensitivity to Wnt pathway inhibitors LGK974 and IWP-2. A general trend of lower IC50 values was observed in 3-dimensional spheroid culture conditions (which allowed enrichment of cells with cancer stem cell phenotype) relative to monolayer cultures. The endocrine-resistant cell lines showed no significant increase in sensitivity to Wnt inhibitors.ConclusionHormone treatment of cultured MCF-7 cells leads within 2 days to increased expression of components of the SOX2 and Wnt pathways and to increased potential for mammosphere formation. We suggest that these responses are indicative of early adaptation to endocrine stress with features of stem cell character and that this facilitates the survival of emerging hormone-resistant cell populations

Correction: Sarkar, D., et al. Multiple Isoforms of ANRIL in Melanoma Cells: Structural Complexity Suggests Variations in Processing. Int. J. Mol. Sci. 2017, 18, 1378

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