Use of radioactive iodine is an essential adjuvant treatment strategy after thyroidectomy in patients with differentiated thyroid carcinoma. Although generally safe, radioiodine therapy has some potential side effects, classified as early and late complications, which we have reviewed in this paper. Early complications include gastrointestinal symptoms, radiation thyroiditis, sialadenitis/xerostomia, bone marrow suppression, gonadal damage, dry eye, and nasolacrimal duct obstruction. The late complications include secondary cancers, pulmonary fibrosis, permanent bone marrow suppression, and genetic effects. As I is an efficacious form of treatment that can significantly decrease the rate of mortality, recurrence, and metastasis, and as the side effects are often minor and well tolerated, radioiodine therapy remains the principal mode of treatment for patients with differentiated thyroid carcinoma.

Overexpression of DNA methyltransferase 1 (DNMT-1) is observed mostly in pancreatic cancer and it can cause tumor suppressor genes silencing in this disease. Recent studies suggest that abnormal expressions of microRNAs (miRs) are involved in pathogenesis of different types of human cancers including pancreatic cancer. In this study we aimed to investigate the effect of miR-148b and -152 on reverting the tumorigenic phenotype of pancreatic cancer cell lines. In order to investigate whether miR-148b and -152 are involved in the regulation of DNMT-1, luciferase reporter assay was used and confirmed that the DNMT-1 mRNA could be a target for miR-148b and miR-152. Furthermore, overexpression of miR-148b and -152 in pancreatic cancer cell lines (MIA PaCa-2 and AsPC-1) decreased DNMT-1 expression (53% and 59% respectively), returned DNA methylation to normal patterns and induced re-expression of tumor suppressor genes, like BNIP3 (4.7- and 3.8-fold) and SPARC (5.3- and 2.9-fold) for miR-148b and -152 respectively. Moreover, the introduced miR-148b and -152 could inhibit the proliferation of MIA PaCa-2 (35% and 37% respectively) and AsPC-1 (39% and 40% respectively) cell lines. The apoptosis rates of MIA PaCa-1 after treatment with miR-148b and -152 were 10% and 8% respectively; while these rates in AsPC-1 were 16% and 11% respectively. Conclusively these findings mean that miRs that are targeting DNMT-1 and modifying methylation status of tumor suppressor genes such as BNIP3 and SPARC can be applied in killing the pancreatic cancer cells and decreasing the tumorigenicity of these cells.

It is observed that upregulation of DNMT3B enzyme in some cancers, including colon cancer, could lead to silencing of tumor suppressor genes. MiR-339 and miR-766 have been predicted to target 3′UTR of DNMT3B gene. Luciferase reporter assay validated that individual and co-transfection of miR-766 and miR-339 into the HEK293T cell reduced luciferase activity to 26% ± 0.41%, 43% ± 0.42 and 64% ± 0.52%, respectively, compared to the control (P < 0.05). Furthermore, transduction of miR-339 and miR-766 expressing viruses into colon cancer cell lines (SW480 and HCT116) decreased DNMT3B expression (1.5, 3-fold) and (3, 4-fold), respectively. In addition, DNA methylation of some tumor suppressor genes decreased. Expression of these genes such as SFRP1 (2 and 1.6-fold), SFRP2 (0.07 and 4-fold), WIF1 (0.05 and 4-fold), and DKK2 (2 and 4-fold) increased in SW-339 and SW-766 cell lines; besides, expression increments for these genes in HCT-339 and HCT-766 cell lines were (2.8, 4-fold), (0.005, 1.5-fold), (1.7 and 3-fold) and (0.04, 1.7-fold), respectively. Also, while in SW-766, cell proliferation reduced to 2.8% and 21.7% after 24 and 48 hours, respectively, SW-339 showed no reduced proliferation. Meanwhile, HCT-766 and HCT-339 showed (3.5%, 12.8%) and (18.8%, 33.9%) reduced proliferation after 24 and 48 hours, respectively. Finally, targeting DNMT3B by these miRs, decreased methylation of tumor suppressor genes such as SFRP1, SFRP2, WIF1 and DKK2 in the mentioned cell lines, and returned the expression of these tumor suppressor genes which can contribute to lethal effect on colon cancer cells and reducing tumorigenicity of these cells.

Objective: Circulating microRNAs (miRNAs), present in body fluids, have been considering importance as cancerbiomarkers. The primary aim of this study was to assess whether circulatory miR-20a and miR-26a can be used asdiagnostic biomarkers in prostate cancer (PCa). Methods: Relative expression miR-20a and miR-26a has been assessedin 40 patients with PCa and 40 non-cancerous volunteer. Sample Collection of patients was performed before and oneweek after prostatectomy. Total RNA was extracted from serum and miR-20a and miR-26a expressions were quantifiedby using Real-Time PCR method. Results: miR-20a was significantly up-regulated in pre-operation serum samples ofPCa patients compared to the serum samples of non-cancerous controls, however, in post-operation samples no significantdifferences was showed. miR-26a level was not significantly decreased in pre and post-operation serum samplescompared to the serum samples of controls. However, the expression level ratios of both miR-20a and miR-26a wereinsignificantly decreased when post-operation serum samples compared to pre-operation ones. Conclusion: Decrementof circulating miR-20a and miR-26a in patients after surgery may reflect the tumoral origin of those microRNAs andthe results may use for tumor remnant monitoring after prostatectomy.