Åsa Wallin

Dicer and miRNA in relation to clinicopathological variables in colorectal cancer patients

BackgroundDicer is aberrantly expressed in several types of cancers. Applying real-time PCR, we detected the expression of Dicer mRNA in normal mucosa (n = 162), primary colorectal cancer (CRC) (n = 162) and liver metastasis (n = 37), and analysed the relationship between Dicer expression and clinicopathological features. We also correlated the expression of Dicer mRNA to the miRNA expression of miR-141, miR-200a, miR-200b, mir-200c and miR-429 in liver metastases.MethodsRT-PCR and qPCR were used to analyse the Dicer expression in normal mucosa, primary tumour and liver metastasis by using the High Capacity cDNA Reverse Transcription Kit and TaqMan™® Gene Expression assays for Dicer and GAPDH. RT-PCR and qPCR were used to detect miRNA expression in liver metastases by utilizing TaqMan® MicroRNA Reverse Transcription Kit and TaqMan® miRNA Assays. Statistical analyses were performed with STATISTICA.ResultsDicer expression in rectal cancer (3.146 ± 0.953) was higher than in colon cancer (2.703 ± 1.204, P = 0.018). Furthermore the Dicer expression was increased in primary tumours (3.146 ± 0.952) in comparison to that in normal mucosa from rectal cancer patients (2.816 ± 1.009, P = 0.034) but this is not evident in colon cancer patients. Dicer expression in liver metastases was decreased in comparison to that of either normal mucosa or primary tumour in both colon and rectal cancers (P < 0.05). Patients with a high Dicer expression in normal mucosa had a worse prognosis compared to those with a low Dicer expression, independently of gender, age, tumour site, stage and differentiation (P < 0.001, RR 3.682, 95% CI 1.749 - 7.750). In liver metastases, Dicer was positively related to miR-141 (R = 0.419, P = 0.015).ConclusionDicer is up-regulated in the early development of rectal cancers. An increased expression of Dicer mRNA in normal mucosa from CRC patients is significantly related to poor survival independently of gender, age, tumour site, stage and differentiation.

Gene Expression Profile of Colon Cancer Cell Lines Treated with SN38

Abstract-Irinotecan has been proven to have anti-tumor effects and is used for chemotherapy in colorectal cancer. It is a prodrug converted by carboxylesterase to form the active metabolite 7-ethyl-10-hydroxy-camptothecin (SN38). To identify the potential molecular function of SN38 in colon cancer, we investigated the gene expression profile of colon cancer cell lines treated with SN38 and tried to reveal critical genes and biological pathways involved in the response of colon cancer cells to SN38 treatment. The analysis indicates that 447 genes (fold change>4, false discovery rate (FDR)<0.05%) were differentially expressed after SN38 treatment. 464 genes (fold change>2) were predicted to be differentially expressed with exposure time. The expression pattern of 1082 genes (fold change>2) may be cell line-specific. 58 colon related genes were annotated in Gene Ontology and 54 important pathways were found from GeneGO database using enrichment analysis. Pathways involved in cell cycle or apoptosis such as DNA-damage-induced apoptosis, role of Small Ubiquitin-like Modifier (SUMO) in p53 regulation were considered as colon cancer significant pathways. The results demonstrated that some cell cycle and apoptosis pathways were affected by SN38. Our results were generally consistent with previous studies on SN38. Moreover, we employed a more powerful biological pathway database and also obtained other colon cancer related pathways such as signal transduction pathways that were all significant in statistic level. We predicted that these pathways may be important to the SN38 treatment in colon cancer and needed to be further validated in experiment.

Gene Expression Profile of Colon Cancer Cell Lines Treated with SN-38

Aim: Colorectal cancer is the third most common form of cancer in the industrial countries. Due to advances regarding the treatments, primarily development of improved surgical methods and the ability to make the earlier diagnosis, the mortality has remained constant during the past decades even though the incidence in fact has increased. To improve chemotherapy and enable personalised treatment, the need of biomarkers is of great significance. In this study, we evaluated the gene expression profiles of the colon cancer cell lines treated with SN-38, the active metabolite of topoisomerase-1 inhibitor irinotecan which leads to cell cycle arrest and apoptosis. Material and Methods: The study included 3 colon cancer cell lines: KM12C, KM12SM and KM12l4a. The 3 cell lines were treated with SN-38, and samples were obtained after 24 and 48 hour treatments. The gene expression analyses were performed using oligonucleotide microarrays comprising of ∼27,000 spots where the untreated controls were compared to the SN-38-treated samples. Results: Unsupervised clustering clearly distinguished the treated cell lines from the untreated. Supervised analysis identified 3,974 significant genes (p = 0.05) differentiating the treated samples from the untreated, majority of which were down-regulated after treatment. The top-ranked down-regulated genes in the treated cell lines included those related to receptor and kinase activity, signal transduction, apoptosis, RNA processing, protein metabolism and transport, cell cycle and transcription. A smaller number of genes were up-regulated in the cell lines after treatment and included genes involved in apoptosis, transcription, development and differentiation. Conclusions: These results demonstrate that the expression of the genes involved in cell proliferation and apoptosis as well as RNA, DNA and protein metabolism were affected by SN-38. The impact of certain genes on colorectal cancer development needs to be further evaluated; however, these results could serve as a basis for further studies in order to find targets for irinotecan treatment.