Tehran University Medical Journal

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Background: Breast cancer is the most common cancer in women. Non-coding RNAs especially miRNAs have important regulatory roles in cancer. MiRNAs are 21-24 nucleotides which have different levels of expression between tumors and normal tissues. In this study, we have analyzed expression level of miR-520d in three different groups of breast cancer.
Methods: Fifty nine samples were divided into different groups according to their immunohistochemistry (IHC) classification: estrogen receptor (ER) positive and/or progesterone receptor (PR) positive group (as group I) human epidermal growth factor receptor 2 (HER2) positive group (as group II) and Triple negative group (as group III). After small RNA extraction from tissues, cDNAs were synthesized and Real time RT-PCR carried out using DNA binding dye. Expression levels were analyzed by LinRegPCR and REST software.
Results: MiR-520d under- expressed in all of three different groups. The expression ratio in groups I ,II, and III were 0.193, 0.167, 0.21, respectively, but only the result from group II was significant (P=0.017). According to the different clinicopathological status of breast cancer, miR-520d underexpressed significantly not only in patients with metastatic lymph node (P=0.019) but also in patients which have cancer at stage III (P=0.036). 
Conclusion: In this study, we found that miR-520d possibly acts as a tumor suppressor. It may be useful for diagnosis of tumor from normal tissue. In addition, miR-520d significantly underexpressed in HER-2 positive group of breast cancers. Therefore, it may be useful as an additional diagnostic test in this group of breast tumors along with other biomarkers.

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Background: Colorectal cancer is the third most common cancer in the world. Non-coding RNA especially miRNAs have important regulatory roles in cancer. miRNAs are small non coding RNA 21-23 nucleotides long which have different levels of expression between tumors and normal tissues. This study was designed to compare expression level of miRNA-21 between Iranian population colorectal cancer tissues and normal tissue. Methods: This case-control study has performed in medical genetics department of Tehran University of Medical Sciences from January to November 2013. We used 35 samples. The samples were isolated from tumor and adjacent normal tissues of colon. Thirty-five samples were divided into different groups according to cliniopathologic features including tumor size (>4 and <4 cm), metastasis (+ and -) and stage. After small RNA extraction from tissues by small RNA purification kit the quality and quan-tity of extracted RNA was determined using spectrophotometry. cDNAs were synthe-sized and real-time polymerase chain reaction carried out. Finally expression levels were statistically analyzed by LinRegPCR and REST software. Results: miRNA-21 expression ratio in stages I, II and III were 1/804 and 4/574, re-spectively, the increase from stage III was statistically significant (P= 0.037). The ex-pression were also studied according to different clinicopathologic status of colon can-cer, tumor size (>4 and <4 cm) and metastatic (+ and -), miRNA-21 over expressed in both groups, however the increase was not statistically significant. Conclusion: In this study, we found miR-21 over-expression in advanced stage in tu-moral tissue comparing with normal adjacent tissue. This means perhaps in the future it would be possible to use miRNA-21 as an informative prognostic biomarker to guide for better treatment strategies for colorectal cancer patients. Our findings also indicate that miRNA-21 is a promising new molecular target for designing novel therapeutic strategies to control colorectal cancer.

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Cystic fibrosis (CF) is the most common autosomal recessive genetic disease, which is caused by defection in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene. CFTR gene codes chloride channels to modulate the homeostasis of epithelial environments. Defective CFTR affects various organs such as the lungs, pancreas, intestine, liver and skin; however, lung impairment is the main reason for mortality in these patients. About 2000 mutations in this gene have been discovered, but nearly 150 mutations lead to serious symptoms. CFTR mutations are classified into six major classes based on phenotypic manifestations such as structural instability of channels, defective processing, malfunctioning chloride-ion transfers and decreased number of chloride channels in the cell membranes. These cause various symptoms such as respiratory infection, intestinal obstruction, pancreatic exocrine insufficiency and malabsorption. Significant improvements in diagnostic tools and methods such as newborn screening, chloride sweat test and gene sequencing have increased the incidence and the prevalence of CF. Enormous studies have also been done on CF recognition and treatment procedures, which have resulted in 30 years of growth in the life expectancy of the patients. Despite the recent achievements, due to the high complexity of this disease and the involvement of various organs, the available treatments are nonpermanent. In the past few years, new combinatorial drugs have been introduced which potentiate and correct CFTR and ameliorate the CF symptoms. Recently, novel genetic engineering methods like CRISPR/Cas9 and TALEN have been utilized to correct the mutated CFTR gene with high accuracy and eradicate the symptoms. Studying this disease at its distinct levels from subcellular to organs could help to find new treatments. Systematic research in finding common attributes between different states of the disease is very beneficial. Interdisciplinary research groups with various expertise in mathematics, biology and engineering could have a great impact on describing the full picture of the disease and development of new treatment strategies. The main part of this article provides a comprehensive overview of cystic fibrosis with emphasis on the key studies on genetics and their effects on cellular and physiological levels. In this work, conventional and new treatment methods have also been discussed.