DNA AND IMMUNOHISTOCHEMICAL ANALYSES OF CANCERS Cancers are diseases which features DNA alterations at the cellular level (Kamel et all., 2017). They are malignant tumors that causes diseases in organs e.g prostrate cancer, breast cancer, colorectal cancer, pancreatic cancer etc. Detecting cancer early is very important because of established association between cancer stage at diagnosis and survival rate. Late stage cancer patient are treated with palliative therapy (Oladeji et al., 2017). The analysis of the genes and surface proteins indicative of cancers would be a necessary prerequisite to better understand the disease and the importance of early diagnosis and effective forms of treatment (Bulusu et al.,2009). Cancers are detected diagnosed and monitored with the aid of biomarkers. Cancer biomarkers are substance or characteristics that are indicative f the presence of cancer (Goosens et al.,2015).Tumors are analyzed using gene expression microarray,  fluorescence in situ hybridization, comparative genomic hybridization and quantitative polymerase chain reaction (Bernard et al., 2002, Abhilash et al., 2008). Microarray is a tool used to analyze gene expression. With the aid of microarrays, researchers have developed gene expression based categories for many malignancies, such as lung carcinoma, leukemia, lymphoma and breast tumors(Bernard et al., 2002, Abhilash et al., 2008). DNA microarray allows the expression of thousands of genes to the monitored simultaneously. The identification and differentiation molecular subtype of tumors are significant in predicting patient’s outcomes (Bernard et al., 2002, Ghosh et al., 2007).  Fluorescent in situ hybridization (FISH) is a molecular cytogenetic technique which uses fluorescent probes to identify and localize the presence or absence of genes on chromosome(Langer-safer et al., 1982,Amann et al.,2008). Comparative genomic hybridization (CGH) is a technique used for genome-wide screening for copy number abberation without the need of cell culturing. The technique involve the tumor DBA being hybridized to normal human metaphase preparation. The fluorescent signal intensity of the tumor DNA compared to that of the normal DNA can be linearly plotted across each chromosome allowing them identify copy number abberation(Weiss et al., 1999, Ghosh et al., 2007  Theisen, 2008). The applications of CGH in cancer research include the screening of tumors for chromosomal abberation, identifying genes involved in the carcinogenesis of certain subtypes of cancers, diagnostic classification and prognosis assessment (Weiss et al., 1999).  Polymerase chain reaction (PCR) is an enzymatic process in which a specific region of the template sequence is amplified yielding many copies of that specific sequence (Butler, 2012). PCR is a method developed on the ability of DNA polymerase to synthesize new strand of DNA complementary to the template strand. PCR’s essential components are template DNA, primers and buffer solution. The primer is used to specify the region of the template sequence need amplifying. The versions of PCR are reverse transcriptase PCR, multiplex PCR and real time PCR. Real time polymerase chain reaction is a recent technological advancement in which the amplified DNA is detected and measured during each cycle of PCR process. In addition to all the components of conventional PCR, a TaqMan probe is required; which is oligonucleotide probe, designed to hybridize with target sequence. During the extension phase of PCR, the TaqMan probe is hydrolysed by the 5′ nuclease activity of Taq polymerase. Taq polymerase is used to detect amplification of specific product (Vega et al., 2001, Mandieh et al., 2013). Other DNA analysis sis include flow cytometry, electrophoresis.


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