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Expression data from MCF7 Scrambled and SIM2si cells

ABSTRACT: MCF7 breast cancer cells are a luminal-type breast cancer with moderate native levels of SIM2s. To determine effects of SIM2s on tumor progression, cells were stably transduced with SIM2si shRNA to knockdown expression, inducing an EMT effect. Microarray analysis was performed to determine genetic pathways involved in this phenotype. The coordination of cellular metabolism is a key factor in the progression of ductal carcinoma in situ (DCIS) to invasive ductal carcinoma (IDC). Pathways regulating the balance between oxidative phosphorylation and glycolysis are unclear. We have found that transcription factor Singleminded-2s (SIM2s), commonly lost with breast cancer progression, contributes to metabolic regulation by controlling glycolytic flux and cellular senescence. Through promotion of p21 and cellular senescence, SIM2s decreases glycolytic enzyme activity and promotes oxidative phosphorylation in breast cancer. These, coupled with increased autophagy and ROS, inhibit tumor growth and metastasis. We use microarrays to detail the global gene programming changes that occur with loss of SIM2s gene expression. Scrambled and SIM2si cells were grown in triplicate for RNA extraction and hybridization on Amersham microarrays.

ORGANISM(S): Homo sapiens

SUBMITTER: Scribner Kelly

PROVIDER: S-ECPF-GEOD-44187 | biostudies-other |

REPOSITORIES: biostudies-other

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Project description:BackgroundHypoxia plays a critical role in the tumor microenvironment by affecting cellular proliferation, metabolism, apoptosis, DNA repair, and chemoresistance. Since hypoxia provokes a distinct shift of microRNA, it is important to illustrate the relative contribution of each hypoxamiR to cancer progression.AimsThe present study aims to shed light on the hypoxamiRs that are involved in pancreatic and breast cancer progression to highlight novel targets for the development of new therapies.MethodsFor 20 cycles, MCF7 breast cancer cells and PANC-1 pancreatic cancer cells were subjected to chronic cyclic hypoxia, which consisted of 72 hours of hypoxia followed by 24 hours of reoxygenation. After 10 and 20 cycles of hypoxia, miRNA expression alterations were profiled using RT-PCR array and further analyzed using a visual analytics platform. The MTT cell proliferation assay was used to determine hypoxic cells' chemoresistance to doxorubicin.ResultsUnder chronic cyclic hypoxia, hypoxic PANC-1 cells have a comparable doubling time with their normoxic counterparts, whereas hypoxic MCF7 cells show a massive increase in doubling time when compared to their normoxic counterparts. Both hypoxic cell lines developed EMT-like phenotypes as well as doxorubicin resistance. According to the findings of miRNet, 6 and 10 miRNAs were shown to play an important role in enriching six hallmarks of pancreatic cancer in the 10th and 20th cycles of hypoxia, respectively, while 7 and 11 miRNAs were shown to play an important role in enriching the four hallmarks of breast cancer in the 10th and 20th cycles of hypoxia, respectively.ConclusionsmiR-221, miR-21, miR-155, and miR-34 were found to be involved in the potentiation of hypoxic PANC-1 hallmarks at both the 10th and 20th cycles, while miR-93, miR-20a, miR-15, and miR-17 were found to be involved in the potentiation of hypoxic MCF7 hallmarks at both the 10th and 20th cycles. This variation in miRNA expression was also connected to the emergence of an EMT-like phenotype, alterations in proliferation rates, and doxorubicin resistance. The chemosensitivity results revealed that chronic cyclic hypoxia is critical in the formation of chemoresistant phenotypes in pancreatic and breast cancer cells. miR-181a and let-7e expression disparities in PANC1, as well as miR-93, miR-34, and miR-27 expression disparities in MCF7, may be associated with the formation of chemoresistant MCF7 and PANC-1 cells following 20 cycles of chronic cyclic hypoxia. Indeed, further research is needed since the particular mechanisms that govern these processes are unknown.

Project description:"To obtain comprehensive information on 17beta-estradiol (E2) sensitivity of genes that are inducible or suppressible by this hormone, we designed a method that determines ligand sensitivities of large numbers of genes using DNA microarray and a set of simple Perl computer scripts implementing the standard metric statistics, and employed it to characterize effects of low (0-100 pM) concentrations of E2 on the transcriptome profile of MCF7/BUS human breast cancer cells, whose E2 dose-dependent growth curve saturated with 100 pM E2. Evaluation of changes in mRNA expression for all genes covered by the DNA microarray indicated that, at a very low concentration (10 pM), E2 suppressed 3~5 times larger numbers of genes than it induced, whereas at higher concentrations (30-100 pM) it induced 1.5~2 times more genes than it suppressed. Using clearly defined statistical criteria, E2-inducible genes were categorized into several classes based on their E2 sensitivities. This approach of hormone sensitivity analysis revealed that expression of two previously reported E2-inducible autocrine growth factors, TGF-? and SDF-1, was not affected by 100 pM and lower concentrations of E2 but strongly enhanced by 10 nM E2, which was far higher than the concentration that saturated the E2 dose-dependent growth curve of MCF7/BUS cells. These observations suggested that biological actions of E2 are derived from expression of multiple genes whose E2 sensitivities differ significantly and, hence, dependent on the E2 concentration especially when it is lower than the saturating level, emphasizing the importance of characterizing the ligand dose-dependent aspects of E2 actions. (paper abstract) Keywords: Dose Response, Time Course MCF7/BUS cells were exposed to varying concentrations of 17beta-estradiol (E2) for 48 hours. Experiments were repeated five times independently. In another experiment, MCF7/BUS cells were subjected to hormone starvation. At day 0, 1, and 2, RNA samples were isolated from cell culture. Experiments were repeated three times independently."

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Expression data from MCF7 Scrambled and SIM2si cells

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