| Summary: | 碩士 === 國立中興大學 === 生命科學院碩士在職專班 === 93 === Lung cancer has increased the most in mortality among all cancers worldwide in recent twenty years. In Taiwan, the average death of lung cancer every year is catching up those of liver cancer, and lung cancer takes the first place of death in female population and keeps on aggravating. Metastasis is the leading cause of death among patients with cancers and has been studied extensively for years. Many genes or proteins involved in invasion and metastasis have been identified and characterized in past decades; however, most of the molecules don’t exist in metastatic cancer cells exclusively, in most cases, they also exist in normal cells. Microarray is a powerful tool to analyze gene expressions parallel and in large quantity, and has been utilized in search the differences of gene expressions as well as classification of diseases.
In earlier studies, studying a series of lung adenocarcinoma cell lines with varying degrees of invasiveness (invasiveness: CL 1-0＜CL 1-1＜CL 1-5) by using cDNA microarrays, we have examined expressions of invasion-associated genes from 31,104 human ESTs（expressed sequence taq）. Microphthalamia-associated transcription factor (MITF) was one the candidate genes, whose expression was negatively correlated with cell line invasiveness. MITF is a member of basic helix-loop-helix-leucine-zipper (bHLH-LZ) type transcription factor family and required for melanocyte-specific transcription of melanogenesis-related enzyme genes. MITF can modulate the expression of other genes, such as tyrosinase, Tyrp1, and Dct.
In this thesis, we stress on exploring the possible role of MITF in tumorigenesis and metastasis further. We measured MITF mRNA expression by real time PCR in 62 non-small cell lung cancer surgical specimens, and correlated with the patient’s clinical outcome. The result showed that the expression of MITF negatively correlated with survival and disease free of lung cancer patients (p=0.008 and 0.024, respectively). We investigated the effect of MITF on the invasion and migration of the lung adenocarcinoma cell line (CL1-0) with less invasive capacity by RNA silencing technology, which revealed that the reduction of MITF promoted tumor cell migration and invasion. In addition, the tumorigenesis analysis in SCID mice showed that the tumor volume derived from the transfectants of MITF-specific siRNA was larger than the scramble controls. To further elucidate the potential mechanisms by which MITF contributes to tumor invasion and tumorigenesis, Affymetrix genechips were used to profile the alterations of gene expression after silencing MITF. Quantitative real-time RT-PCR confirmed the expressions of certain of the targeted genes. The microarray data demonstrated that MITF regulated genes involving in angiogenesis, cell proliferation, signal transduction cell migration and metastasis. Our studies herein provided a new insight into how MITF may contribute to tumor invasion and tumorigenesis.
|
|---|
