Rongxia Liao

MicroRNAs play a role in the development of human hematopoietic stem cells

MicroRNAs (miRNAs) are a class of recently discovered noncoding RNA genes that post‐transcriptionally regulate gene expression. It is becoming clear that miRNAs play an important role in the regulation of gene translation during development. However, in mammals, expression data are principally based on whole tissue analysis and are still very incomplete. We isolated CD34+CD38− hematopoietic stem cells (HSCs) from human umbilical cord blood, on the basis of cell‐surface markers using fluorescence‐activated cell sorting (FACS). Also, CD34+ subpopulation was FACS isolated as the control. Next, using microarray containing oligonucleotides corresponding to 517 miRNAs from human, mouse, and rat genomes, we obtained miRNA gene expression profiles of both subpopulations. We focused on the HSCs correlative miRNAs with comparison to the control. The miRNAs of particular interest were confirmed by real‐time RT‐PCR. HSCs‐overexpressed hsa‐miR‐520h and underexpressed hsa‐miR‐129 were selected for target prediction and analysis. The result showed that EIF2C3 and CAMTA1, genes related to miRNAs processing or transcription regulation, were proved to be real targets for hsa‐miR‐129. And ABCG2, involved in stemness maintaining, a real target for hsa‐miR‐520h. Finally, we chose hsa‐miR‐520h, enriched in HSCs but low in CD34+ cells, for functional characterization, because of its possible role in differentiation of HSCs by regulating ABCG2. As a result, hsa‐miR‐520h transduction into CD34+ cells greatly increased number of different progenitor colonies in Colony‐Forming‐Cell assays, suggesting that hsa‐miR‐520h may promote differentiation of HSCs into progenitor cells by inhibiting ABCG2 expression. This study paves the way for identifying HSC‐specific miRNAs and their roles in HSC development. J. Cell. Biochem. 104: 805–817, 2008.

Detection of lymphangiogenesis in non-small cell lung cancer and its prognostic value

BackgroundOur aim was to detect lymphatic endothelial marker podoplanin, lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1) and vascular endothelial growth factor receptor-3 (VEGFR)-3 and study the prognostic relevance of lymphangiogenesis in non-small cell lung cancer (NSCLC).Materials82 paraffin-embedded tissues and 40 fresh frozen tissues from patients with NSCLC were studied. Tumor samples were immunostained for the lymphatic endothelial markers. Lymphangiogenesis was assessed by immunohistochemical double stains for Podoplanin and Ki-67. The prognostic relevance of lymphangiogenesis-related clinicopathological parameters in NSCLC was evaluated.ResultsWe found that the number of podoplanin positive vessels was correlated positively with the number of LYVE-1 positive vessels. Most of VEGFR-3 positive, few of LYVE-1 positive and none of podoplanin positive vessels were blood vessels. Peritumoral lymphatic vessel density (ptLVD), pathologic stage, lymph node status, lymphatic vessel invasion (LVI), vascular endothelial growth factor-C (VEGF-C) expression and Ki-67 index of the endothelium cells of the micro lymphatic vessels (Ki67%) were associated significantly with a higher risk of tumor progress. ptLVD, pathologic stage, lymph-node metastasis and Ki67% were independent prognostic parameters for overall survival.ConclusionPodoplanin positive ptLVD might play important roles in the lymphangiogenesis and progression of NSCLC. Patients with high podoplanin+ ptLVD have a poor prognosis.

Microarray-based analysis of microRNA expression in breast cancer stem cells

BackgroundThis study aimed to determine the miRNA profile in breast cancer stem cells (BCSCs) and to explore the functions of characteristic BCSC miRNAs.MethodsWe isolated ESA+CD44+CD24-/low BCSCs from MCF-7 cells using fluorescence-activated cell sorting (FACS). A human breast cancer xenograft assay was performed to validate the stem cell properties of the isolated cells, and microarray analysis was performed to screen for BCSC-related miRNAs. These BCSC-related miRNAs were selected for bioinformatic analysis and target prediction using online software programs.ResultsThe ESA+CD44+CD24-/low cells had up to 100- to 1000-fold greater tumor-initiating capability than the MCF-7 cells. Tumors initiated from the ESA+CD44+CD24-/low cells were included of luminal epithelial and myoepithelial cells, indicating stem cell properties. We also obtained miRNA profiles of ESA+CD44+CD24-/low BCSCs. Most of the possible targets of potential tumorigenesis-related miRNAs were oncogenes, anti-oncogenes or regulatory genes.ConclusionsWe identified a subset of miRNAs that were differentially expressed in BCSCs, providing a starting point to explore the functions of these miRNAs. Evaluating characteristic BCSC miRNAs represents a new method for studying breast cancer-initiating cells and developing therapeutic strategies aimed at eradicating the tumorigenic subpopulation of cells in breast cancer.

Role of inhibitor of apoptosis protein Livin in radiation resistance in nonsmall cell lung cancer.

OBJECTIVE The objective of the present study was to explore the role of the inhibitor of apoptosis protein (IAP) Livin in radioresistance in nonsmall cell lung cancer (NSCLC). METHODS Lung adenocarcinoma cell lines A549 and SPC-A1 were used for this study. Using the technique of molecular cloning and gene transfection, two Livin isoforms, Livinα and β, respectively, were expressed in A549 cells with the purpose of exploring the role of Livin in radiation resistance of A549 cells. Moreover, a Livin-specific gene-silencing system was developed using SPC-A1 cell line with the purpose of increasing radiosensitivity of SPC-A1 cells. RESULTS A549 cells were induced by radiation to express Livin isoforms, Livinα and β. A549 cells expressed Livin isoforms stably after gene transfection and the transfected cells demonstrated characteristics of antiradiation. However, Livin gene-silenced SPC-A1 cells exhibited remarkably enhanced radiation sensitivity. CONCLUSION The IAP Livin is an important molecule in antiradiotherapy of NSCLC. Livin-specific gene silencing is likely to be an effective means to enhance radiation sensitivity of lung cancer.

Induced cancer stem cells generated by radiochemotherapy and their therapeutic implications

Local and distant recurrence of malignant tumors following radio- and/or chemotherapy correlates with poor prognosis of patients. Among the reasons for cancer recurrence, preexisting cancer stem cells (CSCs) are considered the most likely cause due to their properties of self-renewal, pluripotency, plasticity and tumorigenicity. It has been demonstrated that preexisting cancer stem cells derive from normal stem cells and differentiated somatic cells that undergo transformation and dedifferentiation respectively under certain conditions. However, recent studies have revealed that cancer stem cells can also be induced from non-stem cancer cells by radiochemotherapy, constituting the subpopulation of induced cancer stem cells (iCSCs). These findings suggest that radiochemotherapy has the side effect of directly transforming non-stem cancer cells into induced cancer stem cells, possibly contributing to tumor recurrence and metastasis. Therefore, drugs targeting cancer stem cells or preventing dedifferentiation of non-stem cancer cells can be combined with radiochemotherapy to improve its antitumor efficacy. The current review is to investigate the mechanisms by which induced cancer stem cells are generated by radiochemotherapy and hence provide new strategies for cancer treatment.

Regulation of miRNAs Affects Radiobiological Response of Lung Cancer Stem Cells

Radiotherapy (RT) is a key therapeutic strategy for lung cancer, the most common cause of cancer-related deaths worldwide, but radioresistance often occurs and leads to failure of RT. It is therefore important to clarify the mechanism underlying radioresistance in lung cancer. Cancer stem cells (CSCs) are considered the fundamental reason for radioresistance. MicroRNAs (miRNAs) have been regarded as important regulatory molecules of CSCs, carcinogenesis, and treatment response of cancers. It is crucial to clarify how regulation of miRNAs affects repair of DNA damage, redistribution, repopulation, reoxygenation, and radiosensitivity (5R) of lung cancer stem cells (LCSCs). A thorough understanding of the regulation of miRNAs affecting 5R of LCSCs has potential impact on identifying novel targets and thus may improve the efficacy of lung cancer radiotherapy.

Molecular mechanism of microRNA involvement in genesis of myelodysplastic syndrome and its transformation to acute myeloid leukemia

Abstract Myelodysplastic syndrome (MDS) is a group of blood-related malignancies caused by disorders of hematopoietic stem cells (HSCs). It is mainly characterized by the ineffective hematopoiesis. Many MDS patients will transform into acute myeloid leukemia (AML) with poor prognosis, often due to infection, hemorrhage and death. However, the molecular mechanism underlying the transformation remains unknown. MicroRNAs (miRNAs), a class of recently discovered noncoding RNA genes that post-transcriptionally regulate gene expression, are considered playing an important role in regulating gene translation during development. Aberrant expression of miRNAs plays an important role in the mutation of HSCs and their transformation to MDS stem cells, suggesting an important mechanism of MDS pathogenesis and its transformation to leukemia. So far, few studies have focused on molecular mechanisms of the transformation of MDS to AML. The role of miRNAs in the transformation needs to be fully understood. Here, we reviewed the molecular mechanism of miRNA involvement in the damage of HSCs, the pathogenesis of MDS and its transformation to leukemia. These results will be of theoretical importance for understanding the mechanism underlying the pathogenesis of MDS, and have potential applications in the prevention and treatment of MDS and in preventing its transformation to leukemia.

Developing cross-cultural competence in Chinese medical students

Every year, at the end of August, there is an influx of new doctors on the wards of hospitals around the United Kingdom. These are medical students that have succeeded through years of examinations and appraisals and are expected to possess the attributes of the General Medical Council’s Tomorrow’s Doctors (GMC 2009). However, there have been concerns as to whether the new flock of doctors are adequately prepared for life on the wards. A recent study in the UK showed that medical patients admitted a week after these doctors began their new jobs had a higher early death rate by 6% (Jen et al. 2009). The authors cited issues regarding patient safety and process measures that could have influenced these results. We believe that working full-time in a hospital demands attributes and knowledge that are different from those gained at medical school and it is this ‘Hidden Curriculum’ that most students are unaware of. Sixty-eight percent of a group of local final-year medical students that we surveyed also agreed that they were inadequately prepared for starting their new job. The main concerns were regards to their lack of knowledge about hospital dynamics, handing over clinical information to seniors and initial assessments of ill patients. The Department of Health recently began a mandatory ‘Preparation to Practice’ module this August to address this. Although there were variations according to hospital and foundation school it mainly consisted of lecture-based tutorials and shadowing period for prospective FY1 doctors on their new jobs for a few days. There is no data yet to see whether this has had a direct impact on patient care. Our experience as junior doctors that have undertaken this scheme has still left us wanting. We feel that the culture of hospital work and the attributes that are necessary can be better instilled at medical school by introducing shadowing periods in the final year. It is also necessary to introduce ‘nearpeer’ led sessions involving current foundation year doctors for this. This would ensure that new concepts such as managing shift work and real-time interaction with other health professionals are introduced earlier making students more familiar with the work ethic of a junior doctor. Despite competence in theoretical and clinical knowledge being examined at medical school, the key to practicing safely as a junior doctor is through this ‘Hidden Curriculum’. This requires trialling various education lead initiatives through cooperation with hospital induction organizers, final-year medical students and current foundation doctors.

A shift of focus is required in English courses for Chinese medical postgraduates

I read with interest the recent article, ‘‘Peer-assisted learning – Beyond teaching: How can medical students contribute to the undergraduate curriculum?’’ (Furmedge et al. 2014), where the authors discussed how peer-assisted learning (PAL) can be used to enhance medical school curriculums. I agree with the case studies in their article, and would also like to suggest the usefulness of PAL with students of allied health professions. I am a final-year medical student and I have sat in lectures, tutorials and followed ward rounds through the last couple of years. All this time, I had been surrounded by other medical students on a similar journey of learning. It was only recently during my general medicine rotation that I came into contact with a student pharmacist for the first time. This was my first encounter with a student allied health professional and I was pleasantly surprised to come away with a valuable learning experience. Through our brief encounter, I picked up important tips that will be useful as a junior doctor. Compared to the occasional pharmacology tutorial I received sporadically, he had 40 months of pharmacy training and this difference was clearly evident in our interaction. I came away from this feeling more confident in prescribing. I wonder why such a good learning opportunity had not happened earlier and more frequently in my medical training to date. I understand that traditionally, medical training had always employed a top down structure, with senior doctors passing down their knowledge and experience to junior doctors and students. More recently, PAL has gained popularity in medical schools across the United Kingdom with many initiatives encouraging medical students to teach one another in both formal and informal settings. Although this is a great initiative, we are neglecting the potential in another form of PAL known as inter-professional education. Multidisciplinary teams are common in healthcare nowadays. Allied health professionals and doctors learn from one another in their daily interactions. It is not difficult to see how encouraging PAL opportunities between student allied health professionals and medical students would help produce better doctors. In the future, medical schools should promote interprofessional education and carry out formal research to ascertain its benefits.

[Study on enhancing sensitivity of SPC-A1 cells to chemotherapy by Livin isoform-specific gene silencing].

BACKGROUND As a new member of inhibitor of apoptosis protein(IAP) family,Livin,especially Livin α,is known to be involved in occurrence and development of lung cancer.Livin is an important mechanism of chemotherapy resistance of lung cancer cell.The aim of this study is to set up Livin isoform(α & β)-specific gene silencing system in SPC-A1 cells by gene transfection and RNA interference(RNAi),and to explore the different functions and value of the isoforms in enhancing chemosensitivity of SPC-A1 cells. METHODS Livinα+β,Livinα and Livinβ specific siRNA were expressed stably in SPC-A1 cells,respectively.MTT was performed to study sensitivity of the cells to chemotherapy drugs.In vivo experiment was performed to test sensitivity of mouse bearing tumor to cisplatin after gene silencing of Livin. RESULTS After silencing of Livinα+β,Livinα and Livinβ genes,sensitivity of SPC-A1 cells to many chemotherapy drugs(including cisplatin,carboplatin,cyclophosphamide and adriblastine) was markedly increased(P < 0.05).Among them,gene silencing of Livinα+β showed the strongest enhancement effect on chemosensitivity of SPC-A1 cells(P < 0.01).Animal experiment showed that tumor inhibition rate of pSilencer-Livinα+β,pSilencer-Livinα and pSilencer-Livinβ groups was 146.1%,130.7% and 110.5%,respectively. CONCLUSIONS The results suggest that Livin isoform,especially Livinα+β is hopeful to be a molecular target for increasing sensitivity of lung cancer cell to chemotherapy.Gene silencing may be a new means of gene therapy for non-small cell lung cancer.