Although we observed OCT4 mRNA expression in 85.7% of lung cancer and 38.8% of non-cancer bronchoscopic biopsy specimens, but OCT4 protein was nearly absent in 50 cases of lung cancer tissues. The reason for this discrepancy is unclear,
but may be due to complex mechanism of post-transcriptional regulation, or potential presence of unknown OCT4 pseudogenes which cause false positive JNJ-26481585 detection by RT-PCR. Therefore, the diagnostic value of OCT4 mRNA in bronchoscopic biopsy specimens requires further investigation. In addition, we examined the correlation of seven stem cell markers expression in bronchoscopic biopsy specimens of lung cancer with patient clinical features. As we know, poorly differentiated cancers show stronger aggressive and metastatic ability . We found the positive expression rates of Nanog and Bmi1 mRNA was inversely correlated to differentiation of lung cancer, indicating these two markers may be useful to predict tumor progression and poor prognosis in lung cancer. Chiou et al.  reported that Nanog expression in surgically resected lung cancer tissues
is an independent prognostic factors of poor prognosis for patients. Vrzalikova and colleagues  also learn more believed that the expression of Bmi1 in surgically resected lung cancer tissues is a prognostic marker in lung cancer. However, surgical resection is not an option for all lung cancer patients, and therefore the use of these markers in bronchoscopic biopsies to predict prognosis would be a great clinical advantage. Conclusions In conclusion, Calpain the expression of
Nanog mRNA in bronchoscopic biopsy specimens is useful diagnostic marker for lung cancer. Further investigation of the diagnostic potential of Nanog in early stages of lung cancer may have a profound clinical impact. Acknowledgements This work was supported by the Key Research Project Grant of Guangxi Health Department (#2012003). We thank NIH 3-MA Fellows Editorial Board for editing the manuscript. References 1. Jemal A, Bray F, Center MM, Ferlay J, Ward E, Forman D: Global cancer statistics. CA Cancer J Clin 2011, 61:69–90.PubMedCrossRef 2. Siegel R, Naishadham D, Jemal A: Cancer statistics, 2012. CA Cancer J Clin 2012, 62:10–29.PubMedCrossRef 3. Reya T, Morrison SJ, Clarke MF, Weissman IL: Stem cells, cancer, and cancer stem cells. Nature 2001, 414:105–111.PubMedCrossRef 4. Visvader JE, Lindeman GJ: Cancer stem cells in solid tumours:accumulating evidence and unresolved questions. Nat Rev Cancer 2008, 8:755–768.PubMedCrossRef 5. Hassan KA, Chen G, Kalemkerian GP, Wicha MS, Beer DG: An embryonic stem cell-like signature identifies poorly differentiated lung adenocarcinoma but not squamous cell carcinoma. Clin Cancer Res 2009, 15:6386–6390.PubMedCrossRef 6. Nguyen GH, Murph MM, Chang JY: Cancer stem cell radioresistance and enrichment: where frontline radiation therapy May fail in lung and esophageal cancers. Cancers 2011, 3:1232–1252.PubMedCrossRef 7.