CRABP2 involvement in a mechanism of Golgi stress and tumor dry matter in non-small cell lung cancer cells via ER dependent Hippo pathway.

Objective: The paper aimed to explore the mechanism of cellular retinoic acid binding protein 2 (CRABP2) involvement in Golgi stress and tumor dryness in non-small cell lung cancer (NSCLC) cells through the estrogen receptor (ER) dependent Hippo pathway.

Methods: Human NSCLC cell line A549 was purchased from ATCC andcultured in RPMI-1640 with 10% FBS. Attractene reagent was used for plasmid transfection. ER (sh) RNA was designed using RNAi Designer. Seventy-six hours after infection, stable cells were obtained after treated with puromycin for 3 weeks. ER silencing cells (with inhibited ER expression) were compared to the control cells (normal cultured NSCLC cell line A549, CRABP2 normal expression). CRABP2 and ER expression levels were detected by RT-PCR. MTT assay was used to detect cell proliferation, and the cell localization of ER and Golgi was observed by confocal microscopy. The invasion and metastasis of cells were analyzed by Boden chamber invasion and migration assays. Western blotting assays was used for detecting the protein expression of E-cadherin, vimentin, ZO-1 protein and epithelial-mesenchymal transition (EMT) related factors.

Results: The lower expression level of mRNA was detected in the ER-silencing group compared to the control group (P<0.05). We also found a higher proliferation level of cells, the number of invading and metastatic cells, the expression of vimentin, p-Lats1T1079, Lats1 and p-YAPS127 mRNA in the control group compared to the ER silencing group (P<0.05). And the expression level of protein kinase RNA-like endoplasmic reticulum kinase (PERK), phosphorylate eukaryotic initiation factor 2 (p-eIF2 alpha), activating transcription factor 4 (ATF4) and C/EBP-homologous protein (CHOP) in the control group was higher than that in the ER silencing group (P<0.05). Adversely, a lower expression level of E-cadherin and ZO-1 protein was found in the control group compared to the ER silencing group (P<0.05).

Conclusion: The expression of CRABP2 in NSCLC cells was regulated by ER, and cell proliferation and invasion were regulated by the Hippo pathway. At the same time, it was found that decreased expression of CRABP2 enhanced endoplasmic reticulum/Golgi stress response.