DNA methylation and miRNA expression in colon adenomas compared with matched normal colon mucosa and carcinomas.

Dysregulation of DNA methylation patterns and non-coding RNA, including miRNAs, has been implicated in colon cancer, and these changes may occur early in the development of carcinoma. In this study, the role of epigenetics as early changes in colon tumorigenesis was examined through paired sample analysis of patient-matched normal, adenoma and carcinoma samples. Global methylation was assessed by genomic 5-methyl cytosine (5-mC) and long interspersed nuclear element-1 (LINE-1) promoter methylation by pyrosequencing. KRAS mutations were also assessed by pyrosequencing. Expression of miRNA, specifically, two microRNA genes-miR-200a and let-7c-was analysed using RT-qPCR. Differences in global methylation in adenomas were not observed, compared with normal tissue. However, LINE-1 methylation was decreased in adenomas (p = .056) and carcinomas (p = .011) compared with normal tissue. Expressions of miRNA, miR-200a and let-7c were significantly higher in adenomas than normal tissues (p = .008 and p = .045 respectively). Thus the significant changes in LINE-1 methylation and microRNA expression in precancerous lesions support an early role for epigenetic changes in the carcinogenic process. Epigenetic characteristics in adenomas may provide potential diagnostic and prognostic therapeutic targets early in cancer development at the adenoma stage.

Use of cervical mucus to screen for gynecological malignancies: a pilot study.

High-grade malignancies are the leading cause of death from gynecological tumors. Unfortunately, no efficient screening method is available for these tumors. In this paper we report the results of a pilot study based on the frequency of TP53 mutations in these cancers. Mucus from the cervix of 32 hysterectomy specimens with no grossly visible cervical or serosal involvement were included in this study. TP53 exons 5-9 mutations were screened for mutations using single strand conformation polymorphism (SSCP). Immunostain for p53 protein was performed in all fallopian tubes and in a sample from the tumors that were identified prospectively. A total of 32 cases including 19 malignant, and 13 benign cases were included. P53 immunostain was positive in only 5 cases including 3 high grade malignant tumors and 2 precancerous lesions (serous tubal intraepithelial lesion or p53 signature) in the fallopian tubes. A TP53 mutation band pattern was detected by SSCP in 2/3 and 2/2 cases respectively. Twenty-seven cases were negative for p53 imunostain, 4 of which were positive for TP53 mutation by SSCP including 3 low-grade malignancies. The results of this study provide evidence that DNA from precursor lesions of high grade ovarian, fallopian tube and endometrial carcinomas can be detected in cervical mucus. Further studies using different markers, in preoperative setting and large scale screening studies will determine the utility of using cervical mucus to screen for gynecological malignancies.