Series Investigation Of The Relationship Between Microsatellite DNA Variations And Lung Squamous Cell Carcinoma Occurrence

Microsatellite DNA also called short tandem repeates (STRs) or simple sequences (SSRs), is a kind of un-coding and number changeable DNA sequences with many repetitive units of 2-6 nucleotides and 10-60bp length each. It distributes extensively in human genome and other eukaryote genome. Microsatellite DNA repetitive unit is small and the length of tandem repeat is short. It is suitable for detection by PCR technique and is widely used in the researches on genetic marker of gene mapping, linkage analysis of virulence gene and loss of gene site or heterozygosity. Studieshave proved that abnormality of microsatellite DNA is one of the mostcommon heredity changes of human malignancy, but in normal tissues variation of microsatellite DNA is rare. In rumors the main abnormality patterns of microsatellite DNA are microsatellite instability (MSI) and loss of heterozygosity (LOH). In one individual the length of microsatellite DNAin tumor tissue is different from that in corresponding normal tissue, which may appear as gain or loss of repetitive units, and this kind of difference is called MSI. In one individual there are two alleles in normal cell DNA but one allele is loss in tumor cell DNA, and this phenomena is called LOH. With the further investigations on microsatellite DNA, whether microsatellite DNA can be a marker for tumor early diagnosis and its feasibility study have become a hot spot in tumor molecular biology.Lung cancer is one of the most common malignancy in the world, the occurrence and development is a complex gradual process involved of multiple factors and multiple procedures. There are a series of gene alterations and gene expression abnormalities from hyperplasia and mutation of bronchus mucous membrane to tumor formation. The variation of microsatellite DNA is an important marker of multi-procedure gene alterations in cellular immortalization and malignancy conversion. Some investigations of microsatellite DNA in lung cancer have been done but they are mainly in lung cancer tissues. The changes of microsatellite DNA in blood and bronchus irrigation fluids are not yet well studied. Investigations on the relations between microsatellite DNA variations and mismatch repaired gene (MMR), cell cycle regulator and proliferating cell nuclear antigen (PCNA) are rare and studies on correlative polygene sites of microsatellite DNA in lung squamous carcinoma have not been reported. So the aim of this study is to investigate the relations between microsatelliteDNA variations and lung squamous carcinoma occurrence and its significance in lung cancer early diagnosis. We used polymerase chain reaction(PCR )-silver stain qualitative method to detect 20 gene sites on chromatosome in the samples of tumor tissues, blood and bronchus irrigation fluids and analysised microsatellite DNA occurrence regularity in order to investigate the application value of microsatellite DNA in lung cancer early diagnosis and the significance of lung cancer occurrence prediction. We also used immunohistochemical method (IHC) to detect hMLHl >PCNA>P53 and P21 expressions in lung cancer tissues in order to investigate their actions and correlations with microsatellite DNA variations.This experiment includes two parts.PART ONE: Investigation of Microsatellite DNA Variations in Lung Squamous CarcinomaMethods1. 20 gene sites were chosen and PCR-silver stain method was used to detect microsatellite DNA in cancer tissues, blood and bronchus irrigation fluid samples from 30 patients with lung squamous carcinoma, the microsatellite DNA in blood samples from 30 patients with lung benign lesions was detected as matched control. Each group was detected 20x30=600 times.2. Statistical Analysis: SPSS statistical package was used to analyse all data with the statistical methods of x2 test, Fisher precise probabilitymethod, t test and variance analysis. A value of P < 0.05 was considered significant and a value of P < 0.01 was considered highly significant. Results1. Microsatel...