Expression Of Glucose Transporter In Non-small Lung Carcinoma Andits Clinical Significance

1. BackgroundMalignant cells are known to have accelerated metabolism, high glucose requirements, and increased glucose uptake. Transport of glucose across the plasma membrane of mammalian cells is the first rate-limiting step for glucose metabolism and is mediated by facilitative glucose transporter (GLUT) proteins. Enhanced tumor uptake of glucose is facilitated by the overexpression of glucose transporter proteins, observed widely in tumor tissue. Glucose utilisation by cancer cells is greatly enhanced when compared with that by normal tissue and begnin lesion tissue.Facilitative glucose transporters are an expanding family of transmembrane proteins that currently has nine members, designated Glut1-5 and Glut7-9 (Glut6 is a pseudogene that was not found to be expressed as protein). Expressions of which were different in different tumors, Glut1 may be the most. Elevated Glut1 expression has been described in many cancers, including lung, breast, colorectal, et al, which wasstrongly associated with lung progression. Glut3 is also overexpressed in lung, laryngeal, et al.Using immunohistochemistry and polyclonal anti-Glut 1 and anti-Glut3 antibodies, the authors immunostained sections of formalin fixed, paraffin embedded tissues from 68 NSCLCs and 17 lung begnin lesions, the mRNA expression with RT-PCR in 34 NSCLC and 10 lung begnin lesions. The aim of this study was to determine the biologic significance of Glutl and Glut3 overexpression in NSCLC.2. Materials and methodsThe thirty-four reacted lung cancer,paracancerous lung tissue and 10 lung benign lesions collected from clinical specimens in the First Affliated Hospital, College of Medicine, Zhejiang Unicersity from October in 2004 to February in 2005. The mRNA expression of Glutl and Glut3 in lung cancer tissues was revealed with RT-PCR, additional 34 NSCLC and 7 lung benign lesions collected from department of pathology in the First Affliated Hospital, College of Medicine, Zhejiang Unicersity from 2004, all of the protein expression with immunohischemical staining. SPSS 11.5 analyze the data.3. ResultsOf the 68 cases, 58(85.3%) were Glutl positive, including 34(100%) were squamous cell carcinoma positive, 24(70.5%) were adenocarcinoma positive;18(26.5%) were Glut3 positive, including 14(41.2%) were squamous cell carcinomapositive, 4(11.8%) were adenocarcinoma positive. The appearance of Glutl positive clones is associated with histological types, differentiations, tumor size, and pathologic stages;Glut3 was not significant different between histological types, differentiations, tumor size, and pathologic stages. All Glut3 positive tumors were positive for Glutl.All lung benign lesions were negative for Glutl and Glut3.The relative mRNA expressions of Glutl and Glut3 were 0.689± 0.245,0.506± 0.246 in 34 NSCLC tissues, and 0.338 ± 0.157,0.482± 0.238 in paracancerous lung tissues, 0.32K 0.442 in lung begnin lesions, the difference of Glutl mRNA was significant(/=9.07, PO.001) between cancer tissues and paracancerous lung tissues , but Glut3 mRNA was not(P>0.05).4. Conclusion1) Expression of Glutl was strongly associated with NSCLC progression.2) Glut3 overexpression was weak in NSCLC, Which likely occurs after Glutl overexpression, which is worsened by the emergence of Glut3 positive clones.3) Glutl and Glut3 are significant prognostic indicators in cases of NSCLC.