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Oncotarget. 2016 Nov 22;7(47):76827-76839. doi: 10.18632/oncotarget.12718.

Activation of endoplasmic reticulum stress promotes autophagy and apoptosis and reverses chemoresistance of human small cell lung cancer cells by inhibiting the PI3K/AKT/mTOR signaling pathway.

Author information

1
Department of Radiation Oncology, Shandong Provincial Qianfoshan Hospital, Shandong University, Jinan 250014, P.R. China.
2
Medical Research Center, Shandong Provincial Qianfoshan Hospital, Shandong University, Jinan 250014, P.R. China.
3
Medical Management Service Center of Shandong Provincial Health and Family Planning Commission, Jinan 250014, P.R. China.

Abstract

OBJECTIVE:

This study aims to investigate the effects of endoplasmic reticulum stress (ERS) on autophagy, apoptosis and chemoresistance of human small cell lung cancer (SCLC) cells via the PI3K/AKT/mTOR signaling pathway.

RESULTS:

The expressions of ERS-related proteins (PEAK, eIF2α and CHOP) up-regulated, autophagy-related proteins (LC3, LC3-II and Beclin1) and apoptosis-related proteins (Bax and procaspase-3) down-regulated in NCI-H446 and H69 cells after tunicamycin treatment for 24 h. Compared with the blank group, the tunicamycin, BEZ235 and tunicamycin + BEZ235 groups exhibited decreased expressions of p-PI3K, p-AKT and p-mTOR, and increased expressions of autophagy-related proteins (LC3, LC3-II and Beclin1) and apoptosis proteins (Bax and procaspase-3), and the most obvious changes were observed in the tunicamycin + BEZ235 group.

MATERIALS AND METHODS:

CCK-8 assay was applied to select the best cell line from five SCLC cell lines (NCI-H446, H69, H526, H146 and H209). Finally, NCI-H446 and H69 cells were selected for further experiments. NCI-H446/CDDP and H69/CDDP were selected and divided into the blank group, tunicamycin (an ESR inducer) group, BEZ235 (inhibitors of PI3K/AKT/mTOR pathway) group and tunicamycin + BEZ235 group. Cell apoptosis was detected by flow cytometry. Autophagy was observed by fluorescence microscopy and flow cytometry. Western blotting was used to detect the expressions of ERS-related proteins, autophagy-related proteins, apoptosis-related proteins and PI3K/AKT/mTOR pathway-related proteins.

CONCLUSIONS:

Our findings provide evidence that the activation of ERS could promote autophagy and apoptosis and reverse chemoresistance of human SCLC cells by inhibiting the PI3K/AKT/mTOR pathway.

KEYWORDS:

PI3K/AKT/mTOR signaling pathway; apoptosis; autophagy; endoplasmic reticulum stress; small cell lung cancer

PMID:
27765907
PMCID:
PMC5363552
DOI:
10.18632/oncotarget.12718
[Indexed for MEDLINE]
Free PMC Article

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