Project description:Deficiencies in the ATM gene are the underlying cause for ataxia telangiectasia, a congenital syndrome characterized by neurological, motor and immunological defects, as well as a predisposition to cancer risks. MicroRNAs (miRNAs) are small regulators of post-transcriptional gene expression and a useful tool for cancer diagnosis, staging, and prediction of therapeutic responses to clinical regimens. In particular, miRNAs have been used to develop signatures for breast cancer profiling. We are interested in the consequences of ATM deficiency on miRNA expression in breast epithelial cells and the potential contribution to cancer predisposition. In this study we investigate the effects of ATM loss on the miRNA expression and related gene expression changes in normal human mammary epithelial cells (HME-CC). We have identified 81 significantly differently expressed miRNAs in the ATM-deficient HME-CCs using small RNA sequencing. Many of these differentially expressed miRNAs have been described and implicated in tumorigenesis and proliferation. These changes include down-regulation of tumor suppressor miRNAs, such as hsa-miR-29c and hsa-miR-16, as well as the over-expression of pro-oncogenic miRNAs hsa-miR-93 and hsa-mir-221. All 81 miRNAs were combined with genome wide gene expression profiles to investigate possible targets of miRNA regulation. We identified messenger RNA (mRNA) targets of these miRNAs that were also significantly regulated after the depletion of ATM. Predicted targets included many genes implicated in cancer formation and progression, including SOCS1 and the proto-oncogene MAF. Integrated analysis of miRNA and mRNA expression allows us to build a more complete understanding of the pathways and networks involved in the breast cancer predisposition observed in individuals deficient in ATM. This study highlights miRNA and predicted mRNA target expression changes in ATM-deficient HME-CCs and suggests a mechanism for the breast cancer-prone phenotype seen in ATM deficient cells and patients. Additionally, this study provides preliminary data for defining miRNA profiles that may be used prognostic biomarkers for breast cancer predisposition. Examination of small RNA population in human mammary epithelial cell lines. Each condition was preformed in triplicate. This submission represents the transcriptome component of study.

Project description:Deficiencies in the ATM gene are the underlying cause for ataxia telangiectasia, a congenital syndrome characterized by neurological, motor and immunological defects, as well as a predisposition to cancer risks. MicroRNAs (miRNAs) are small regulators of post-transcriptional gene expression and a useful tool for cancer diagnosis, staging, and prediction of therapeutic responses to clinical regimens. In particular, miRNAs have been used to develop signatures for breast cancer profiling. We are interested in the consequences of ATM deficiency on miRNA expression in breast epithelial cells and the potential contribution to cancer predisposition. In this study we investigate the effects of ATM loss on the miRNA expression and related gene expression changes in normal human mammary epithelial cells (HME-CC). We have identified 81 significantly differently expressed miRNAs in the ATM-deficient HME-CCs using small RNA sequencing. Many of these differentially expressed miRNAs have been described and implicated in tumorigenesis and proliferation. These changes include down-regulation of tumor suppressor miRNAs, such as hsa-miR-29c and hsa-miR-16, as well as the over-expression of pro-oncogenic miRNAs hsa-miR-93 and hsa-mir-221. All 81 miRNAs were combined with genome wide gene expression profiles to investigate possible targets of miRNA regulation. We identified messenger RNA (mRNA) targets of these miRNAs that were also significantly regulated after the depletion of ATM. Predicted targets included many genes implicated in cancer formation and progression, including SOCS1 and the proto-oncogene MAF. Integrated analysis of miRNA and mRNA expression allows us to build a more complete understanding of the pathways and networks involved in the breast cancer predisposition observed in individuals deficient in ATM. This study highlights miRNA and predicted mRNA target expression changes in ATM-deficient HME-CCs and suggests a mechanism for the breast cancer-prone phenotype seen in ATM deficient cells and patients. Additionally, this study provides preliminary data for defining miRNA profiles that may be used prognostic biomarkers for breast cancer predisposition.

Project description:Introduction: MicroRNAs (miRNAs) are small, non-coding RNA molecules involved in post-transcriptional gene regulation and have recently been shown to play a role in cancer metastasis. In solid tumors, especially breast cancer, alterations in miRNA expression contribute to cancer pathogenesis, including metastasis. Considering the emerging role of miRNAs in metastasis, the identification of predictive markers is necessary to further understanding of stage-specific breast cancer development. This is a retrospective analysis that aimed to identify molecular biomarkers related to distant breast cancer metastasis development. Methods: A retrospective case cohort study was performed in 64 breast cancer patients treated during the period from 1998-2001. The case group (n=29) consisted of patients with a poor prognosis who presented with breast cancer recurrence or metastasis during follow up. The control group (n=35) consisted of a random sample of patients with a good prognosis who did not develop breast cancer recurrence or metastasis. These patient groups were stratified according to TNM clinical stage (CS) I, II and III, and the main clinical features of the patients were homogeneous. miRNA profiling was performed using formalin-fixed, paraffin-embedded tumors. Biomarkers related to metastatic potential were identified independent of clinical stage, and a cutoff point was selected based on the optimal sensitivity and specificity (ROC curve). Finally, a hazard risk analysis of these biomarkers was performed to evaluate their relation to metastatic potential. Results: miRNA expression profiling identified several miRNAs that were either specific and shared across all clinical stages (p?0.05). Among these, we identified miRNAs previously associated with cell motility (let-7 family), cell proliferation and invasion (hsa-miR-16 and has-miR-205) and distant metastasis (hsa-miR-21). In addition, hsa-miR-494 and hsa-miR-21 were up-regulated in metastatic cases of CSI and II. Furthermore, the combination of the 3 miRNAs identified for CSII (hsa-miR-494, hsa-miR-183 and hsa-miR-21) was significant and were a more effective risk marker compared to the single miRNAs. Conclusions: Women with metastatic breast cancer, especially CSII, presented up-regulated levels of miR-183, miR-494 and miR-21, which were associated with a poor prognosis. These miRNAs therefore represent new risk biomarkers of breast cancer metastasis and may be useful for future targeted therapies.

Project description:Little is known about the alterations in microRNA (miRNA) expression patterns during the consecutive stages of cervical cancer development and their association with chromosomal instability and epigenetic changes. We integrated miRNA expression profiles in normal cervical squamous epithelium, high-grade precancerous lesions (CIN2-3), squamous cell carcinomas (SCC) and adenocarcinomas (AdCAs) with previously generated chromosomal profiles of the same samples. In addition, the DNA methylation status of downregulated miRNAs located in a CpG island was determined. Significantly differential expression during the consecutive stages of cervical SCC development was observed for 106 miRNAs. Altered expression of 5 significantly differentially expressed miRNAs, hsa-miR-9 (1q23.2), hsa-miR-15b (3q25.32), hsa-miR-28-5p (3q27.3), hsa-miR-100 and hsa-miR-125b (both 11q24.1) was directly linked to frequent chromosomal alterations. Another 9 significantly downregulated miRNAs were located within a CpG island. Three of these 9 miRNAs, hsa-miR-203, hsa-miR-572, and hsa-miR-638, showed increased methylation in cervical cancer cell lines and HPV-immortalised cells compared to primary keratinocytes. Functional analyses were performed for hsa-miR-9, representing a potential oncogene with increased expression linked to a chromosomal gain, and hsa-miR-203, representing a potential tumour suppressor gene silenced by DNA methylation. Hsa-miR-9 and hsa-miR-203 were found to alter cell viability and anchorage independent growth in vitro, respectively, supporting their oncogenic and tumour suppressive function in cervical cancer. In conclusion, differential expression of 106 miRNAs, partly associated with chromosomal alterations and epigenetic changes, was observed during cervical SCC development. Altered expression of hsa-miR-9 and hsa-miR-203 was shown to be functionally relevant, underlining the importance of deregulated miRNA expression in cervical carcinogenesis. 10 squamous cell carcinomas of the cervix, 9 adenocarcinomas of the cervix, 18 high-grade cervical intraepithelial neoplasias (CIN2-3), and 10 cervical squamous epithelial samples with normal histology were analysed using single channel (Cy3) miRNA microarrays from Agilent (G4471A-016436).

Project description:Comparison af adherent growing breast cancer cell lines versus mammospheres under serum-free conditions Background: In patients with breast cancer, subsets of long-lived cells tolerate chemotherapies. These chemoresistant cells can remain dormant at secondary sites, such as bone and lung, for years and decades. Cancer cells endowed with drug resistance are maintained in vivo in a quiescent slow-growing state that preserves them from anti-proliferative cancer drugs. The mechanism of conversion from dormancy to growth remains poorly understood. We aimed to identify microRNAs (miRNAs) as master regulators of cancer stem cells (CSCs) maintainance, because one of the characteristics of CSCs is their slow proliferation or dormancy. MiRNA targeting CSCs may be an effective therapy to improve the prognosis of breast cancer patients. Methods: We performed miRNA array analysis to identify differences miRNA expression profiles between adherent cells and mammospheres that contain higher number of breast cancer stem cells (BCSCs). In this approach, we focused on expression of hsa-miR-27a. Further, roles of hsa-miR-27a target genes in maintaining BCSC properties were analysed . Results: Here, we showed that hsa-miR-27a was downregulated in mammosphere cells. The formation of BCSCs was attenuated by transfection of hsa-miR-27a. We found that hsa-miR-27a targets F-box and WD-40 domain protein 7 (FBW7), a tumor suppressor gene, thereby inducing tumor dormancy. Additionally, we found that hsa-miR-27a targets genes involved in GSH synthesis, including xCT (encoded by SLC7A11), a heterodimeric protein of a transporter subunit of the xC(-) system, cystathionine gamma-lyase (CTH/CSE), and nuclear factor-erythroid 2-related factor 2 (Nrf2/NFE2L2), thereby increasing intracellular reactive oxygen species (ROS) levels. Upregulation of these genes by antisense (as)-miR-27a induced autophagy. Conclusions: Previous studies showed that expression of hsa-miR-27a is elevated in breast cancer. Here, we showed that expression of hsa-miR-27a was reduced in BCSC. CSCs in the dormant state are resistant to chemotherapy due to inhibition of ROS accumulation in these cells. These results demonstrate that hsa-miR-27a plays an essential role in maintaining the BCSCs phenotype via regulation of FBW7, ROS related genes and the Nrf2 pathway, as well as in the dormant-to-proliferative switch of breast cancer cells. Thus, hsa-miR-27a represents a novel strategy for various type of breast cancer.

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Small RNA-seq and gene expression analysis reveal a miRNA profile of cancer-susceptibility in ATM deficient human mammary epithelial cells (Small RNA-Seq)

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Genome-wide small RNA sequencing and gene expression analysis reveals a microRNA profile of cancer susceptibility in ATM-deficient human mammary epithelial cells.

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