Background
Lung cancer has been considered as one of the most important causes of cancer-related mortality worldwide. To predict lung cancer, researchers identified several molecular markers. However, many underlying markers of lung cancer remain unclear. One of these markers is Rab GDP dissociation inhibitor beta (GDIβ), which is related to tumorigenicity, development and invasion. This study was designed to analyze the biological characteristics of Rab GDIβ and to detect the mRNA and protein expressions of Rab GDIβ in lung cancer cells; this study also aimed to investigate the functions of this protein in lung cancer. Method: Using online software from the websites of NCBI, ProtParam and so on, we analyzed the biological characteristics of Rab GDIβ. RT-PCR was performed to detect gene expressions in A549 and 16HBE cell lines and immunohistochemistry (IHC) staining was conducted to detect Rab GDIβ protein expression in 57 cases of human lung cancer tissues and 19 cases of normal lung tissues. The association of protein expression with patient clinical and pathological characteristics was assessed in each dataset.
Conclusion
The expression of Rab GDIβ was low in non-small cell lung cancer (NSCLC). Hence, Rab GDIβ may be a tumor suppressor and could function as an indicator of tumorigenesis in NSCLC; nevertheless, this result should be further studied. Virtual slides: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2014_201.
Results
Bioinformatic analysis on Rab GDIβ: The mRNA of human Rab GDIβ contains two transcript variants; the common structural elements of the two proteins are mainly α-helix, random coil, β-turn and extended strand. Three and four transmembrane domains could be found in the entire polypeptide chain of protein variants 1 and 2, respectively; both transcript variants are hydrophilic and soluble proteins. The RT-PCR result: The mRNA expression of Rab GDIβ was down-regulation in A549 cells compared with that in 16HBE cells. The IHC result: The protein expression of Rab GDIβ in lung cancer cells was significantly lower than that in normal lung tissues (P <0.05) but was not correlated with patients' age, gender, tumor size, pathological type, differentiation, lymph node metastasis, distant metastasis and TNM stage.