Background: Abnormal expressions of microRNAs are related to various cancers such as breast cancer for which paclitaxel is widely used as a chemotherapeutic agent. We aimed to investigate the effect of paclitaxel treatment on the expression level of miR-199a-5p and miR-10b, involved in epithelial-mesenchymal transition (EMT) process in breast cancer cell lines. Methods: Human breast cancer cell lines BT-474, SKBR-3, MDA-MB-231, and MCF-7 were cultured and MTT assay was used to determine IC50 of paclitaxel. RNA was extracted, cDNA was synthesized, and the expression level of miRNAs and genes was quantitatively determined using real-time PCR. Results: After treatment with paclitaxel, the expression level of miR-199a-5p significantly decreased in MCF-7 and SKBR-3 cell lines, while it increased in MDA-MB-231 and BT-474. The expression level of miR-10b was also significantly reduced in MCF-7, MDA-MB-231, and SKBR-3 and increased in BT-474 cell lines following treatment with paclitaxel. Our results further indicated that paclitaxel reduced the expression level of vimentin and MMP-9 in MDA-MB-231 cell line. Conclusion: Our findings revealed the increased expression of EMT-inhibitor miR-199a-5p and the decreased expression of metastamiR miR-10b after treatment of MDA-MB-231 metastatic breast cancer cell line. Reduced expressions of vimentin and MMP-9 were also observed, corroborating the inhibition of metastasis markers in this type of breast cancer. The therapeutic effect of paclitaxel may in part be due to the change in the balance of EMT-promoting and EMT-inhibiting miRNAs.

Background: Metastasis-associated miRNA (metastamiR) harbors a great potential to confine metastasis as the most lethal aspect of cancer. miR-193b-3p is an anti-metastatic miRNA, whose expression significantly decreases in metastatic breast cancer cells. Objectives: In the present study, the expression patterns of different cell-lines were investigated, following an effective miR transfection strategy. Methods: Double-stranded oligo of mature miR-193b-3p, miR-negative, and miR-LacZ were designed and cloned into pcDNA6. 2gw/EmGFP plasmid. Calculating the population doubling time (PDT), non-tumorigenic MCF-10A, tumorigenic but non-metastatic MCF-7, and metastatic MDA-MB231 were transfected by Lipofectamin2000 and Express-In. The expressions of miR-193b-3p and miR-191 have been quantified by Real-time PCR 48 hours after transfection. Scratch, Transwell migration, and Matrigel invasion assays have been carried out to assess the migration and invasion levels of the cell-lines. Results: The PDT (21. 27 ± 0. 43, 28. 18 ± 0. 34, and 35. 83 ± 0. 44 hours) and miR-193b-3p relative expression before transfection (100, 42 and 8) were measured for MCF-10A, MCF-7, and MDA-MB231 cell-lines, respectively. Better transfection results were obtained based on nano-liposome method. The expression of the miR-193b-3p was increased 32, 19 and, 65 fold-change. The rate of invasion in metastatic cells was 6. 6 fold-higher in comparison to MCF-7 cells. Conclusions: Higher expression rate of the miRNA is anticipated to occur, following miR-mimic transfection. However, the observed differential patterns of miRNA increase in the context of different cell-lines, indicating the involvement of more complicated cellular pathways. Scrutinizing these cellular mechanisms could open new horizons in cancer therapy and management strategies.

Statement of the Problem: Head and neck cancers include epithelial tumors arising in the oral cavity, pharynx, larynx, paranasal sinuses, and nasal cavity. Metastasis is a hallmark of cancer. MicroRNAs (miRNAs) are endogenous small noncoding RNAs involved in cell proliferation, development, differentiation and metastasis. It is believed that miRNA alterations correlate with initiation and progression of cancer cell proliferation or inhibition of tumorigenesis. Moreover, miRNAs have different roles in development, progression, and metastasis of head and neck squamous cell carcinoma (HNSCC). Altered expression of miRNAs could be novel molecular biomarkers for the definite diagnosis of cancer, metastatic site, cancer stage, and its progression.Purpose: The purpose of this review was to provide a comprehensive literature review of the role of miRNAs in head and neck cancer metastasis. Search strategy: A relevant English literature search in PubMed, ScienceDirect, and Google Scholar was performed. The keywords ‘miRNA’, ‘head and neck’, and ‘cancer’ were searched in title and abstract of publications; limited from 1990 to 2015. The inclusion criterion was the role of miRNAs in cancer metastasis. The exclusion criterion was the other functions of miRNAs in cancers. Out of 15221 articles, the full texts of 442 articles were retrieved and only 133 articles met the inclusion criteria.Conclusion: Despite the advances in cancer treatment, the mortality rate of HNSCC is still high. The potential application of miRNAs for cancer therapy has been demonstrated in many studies; miRNAs function as either tumor suppressor or oncogene. The recognition of metastamiR and their targets may lead to better understanding of HNSCC oncogenesis, and consequently, development of new therapeutic strategies which is a necessity in cancer treatment. Development of therapeutic agents based on miRNAs is a promising target.