Abstract: Objective To investigate the expression of connexin 26 (Cx26) in lung adenocarcinoma associated fibroblasts and its clinical significance. Methods The 6 cases of lung adenocarcinoma tissues and adjacent normal lung tissues that were surgically resected in Guangxi Medical University Cancer Hospital from November 2018 to May 2019 were collected, and the primary cancer-associated fibroblasts (CAFs) and normal lung fibroblasts (NLFs) were isolated.The primary fibroblasts were identified through the cell morphology observed by optical microscope, the expression level of cell biomarkers α-SMA, E-cadherin and Vimentin detected by the Western blot and immunofluorescence staining; the level of Cx26 mRNA was detected by qRT-PCR. The distribution and expression of Cx26 in 22 cases of lung adenocarcinoma and adjacent tissues collected from January 2013 to December 2018 were detected by immunofluorescence staining. Results The primary CAFs and NLFs were successfully isolated. The microscopy reported that CAFs and NLFs were spindle-shaped cells, both of which expressed α　-SMA and Vimentin, but only slightly expressed E-cadherin, and the expression level of α-SMA in CAFs was higher than that in NLFs (P<0.001).The qRT-PCR results showed that the expression level of Cx26 in CAFs showed a continuous downward trend with the increase of tumor stage(t=5.684, P=0.011). The immunofluorescence staining results showed that the expression of Cx26 in lung adenocarcinoma tissues was lower than that in normal lung tissues (t=2.609, P=0.016). Conclusions Downregulation of Cx26 expression in CAFs within tumor microenvironment may be associated with higher stage and progressive malignancy of lung adenocarcinoma.

Key words: Lung adenocarcinoma, Fibroblasts, Connexin, CAFs, NLFs