[CacyBP promotes the proliferation and invasion of non-small cell lung cancer]

Objective: To investigate the effects and the mechanism of Calcyclin-binding protein (CacyBP) on the proliferation and invasion of non-small cell lung cancer (NSCLC) cells. Methods: Six lung cancer tissues and paired normal lung tissues were collected from NSCLC patients who underwent surgical treatment in Jinan Central Hospital during 2016. The expression of CacyBP in these tissues was examined by western blot. The protein and mRNA expression of CacyBP in human bronchial epithelial cells (16HBE), NSCLC cell lines including A549, H1299, H460 and H1975 were examined by western blot and reverse transcription-polymerase chain reaction (RT-PCR), respectively. RNAi and shRNA against negative control (NC) or CacyBP were transfected into A549 cell which were denoted as siNC group, siCacyBP-1 group, sicacyBP-2 group, shNC group and shCacyBP group, respectively. Control and Flag-CacyBP plasmids were transfected into A549 cells which were denoted as NC group and Flag-CacyBP group, respectively. Cell counting kit-8 (CCK-8), plate clone formation assay and flow cytometry assay were used to assess cell proliferation ability and cycle of A549. Wound healing assay and transwell assay were used to assess abilities of A549 cells migration and invasion. The protein expressions of epithelial-mesenchymal transition (EMT) markers including E-cadherin, N-cadherin, Snail1, Vimentin, and phosphorylation of protein kinase B (p-Akt) were examined in CacyBP depleted or overexpressed A549 cells. Results: The CacyBP protein level in NSCLC tissues was 0.41±0.23, significantly higher than 0.11±0.04 in normal lung tissues (P<0.05). The CacyBP protein expression levels in different NSCLC cell lines including A549, H1299, H460 and H1975 were 0.35±0.01, 0.38±0.01, 0.32±0.01 and 0.41±0.01, respectively, which were significantly higher than 0.03±0.01 in 16HBE cells (P<0.05). The result of RT-PCR was consistent with that of western blot. Compared with siNC group (absorbance was 1.54±0.03), siCacyBP-1 group and siCacyBP-2 group showed decreased cell proliferation (absorbances were 1.38±0.04 and 1.34±0.03, P<0.05). The number of cell colony in shNC group was 41.33±3.21, significantly higher than 22.00±3.61 in shCacyBP group (P<0.05). The proportion of G(1) phase in shCacyBP group was (61.35±5.45)%, higher than (49.61±1.54) % in shNC group (P<0.05). The proportion of S phase was (25.41±3.21)%, which was lower than (38.68±0.46)% of shNC group (P<0.05). The cell migration rate of shCacyBP group was (12.67±0.71)%, which was significantly lower than (35.50±2.07)% of shNC group (P<0.05). The numbers of cell migration and invasion in shNC group were 406.33±7.37 and 92.33±8.50, respectively, which were significantly higher than 224.67±10.01 and 66.00±7.94 in shCacyBP group (P<0.05). Compared with siNC group, the expression of epithelial marker E-cadherin was up-regulated, while the expressions of mesenchymal markers including N-cadherin, Vimentin, Snail1 and p-Akt were down-regulated in CacyBP depleted A549 cells. Compared with NC group, overexpression of CacyBP inhibited E-cadherin expression while promoted the expressions of N-cadherin, Snail1, Vimentin and p-Akt, which could be restored by LY294002. Conclusion: CacyBP may promote the proliferation and invasion of NSCLC cells by regulating Akt signal pathway.