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Published on: January 19, 2019
Autophagy regulates vinorelbine sensitivity due to continued Keap1-mediated ROS generation in lung adenocarcinoma
Yan-Wei Wu1, Chiou-Feng Lin2, Yee-Shin Lin3
11Department of Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
Abstract:
Autophagy is one of the induced mechanisms in metastatic cancer to escape death due to starvation, hypoxia, metabolic stresses, chemotherapy, and radiation. Some publications have revealed that chemotherapy combined with autophagy inhibitor will overcome drug resistance. We modified AS2 cells with PTEN overexpression, mTOR knockdown, or Keap1 knockdown, and made modification of A549 cells with PTEN knockdown, Atg5 knockdown, and Keap1 overexpression. Our study was aimed toward an exploration of how autophagy modulates Keap1, ROS generation, and vinorelbine-induced apoptosis in these cell lines. We found that lung cancer PC14PE6/AS2 (AS2) had higher mTOR and Akt and also lower PTEN expression than A549 cells. Descended autophagy was demonstrated with more decreased p62 accumulation and LC3 II conversion in AS2 cells as compared to A549 cells. The A549 cells had lower Keap1/Nrf2 and more active anti-oxidant response element (ARE) activity than the AS2 cells. We modified AS2 cells with PTEN overexpression, mTOR knockdown, Keap1 knockdown, and revealed amplified p62 and LC3 expression accompanied with decreased Akt, Keap1, ROS, and vinorelbine-induced apoptosis. Declined p62, LC3 expression were accompanied with increased Akt, Keap1, ROS, and vinorelbine-induced apoptosis after modification of A549 cells with PTEN knockdown, Atg5 knockdown, and Keap1 overexpression. Keap1 overexpression lowered ARE levels in A549 cells, and ARE level exhibited up-growth in Keap1 knockdown AS2 cells. The autophagy inhibitor caused more ROS generation and vinorelbine-induced apoptosis in the A549 and CL1-5 cells. According to these findings, autophagy regulates vinorelbine sensitivity by continuing Keap1-mediated ROS generation in lung adenocarcinoma cells.
Insights
Autophagy promotes cancer cell survival but inhibiting it increases sensitivity to chemotherapy. This study shows autophagy regulates Keap1-mediated ROS generation, impacting vinorelbine-induced apoptosis in lung adenocarcinoma.
Area of Science:
- Cell Biology
- Oncology
- Biochemistry
Background:
- Autophagy is a cellular process that cancer cells utilize to survive various stresses, including chemotherapy.
- Inhibiting autophagy has shown promise in overcoming drug resistance in metastatic cancer.
- Understanding the intricate mechanisms of autophagy in lung cancer is crucial for developing effective therapeutic strategies.
Purpose of the Study:
- To investigate how autophagy influences Keap1, reactive oxygen species (ROS) generation, and vinorelbine-induced apoptosis in modified lung cancer cell lines.
- To explore the differential expression of key proteins like PTEN, mTOR, Akt, and Keap1 in AS2 and A549 lung cancer cells.
- To elucidate the role of autophagy in regulating chemoresistance and sensitivity in lung adenocarcinoma.
Main Methods:
- Genetic modification of lung cancer cell lines (AS2 and A549) involving PTEN, mTOR, Keap1, and Atg5.
- Assessment of autophagy markers such as p62 accumulation and LC3 II conversion.
- Measurement of reactive oxygen species (ROS) generation and anti-oxidant response element (ARE) activity.
- Evaluation of vinorelbine-induced apoptosis in response to genetic modifications and autophagy inhibition.
Main Results:
- AS2 cells exhibited higher mTOR/Akt and lower PTEN expression with decreased autophagy compared to A549 cells.
- Modifications like PTEN overexpression or Keap1 knockdown in AS2 cells increased autophagy markers (p62, LC3 II) and decreased ROS and apoptosis.
- Conversely, PTEN or Atg5 knockdown and Keap1 overexpression in A549 cells reduced autophagy markers, increased ROS, and enhanced vinorelbine-induced apoptosis.
- Autophagy inhibition augmented ROS generation and vinorelbine-induced apoptosis in A549 and CL1-5 cells.
Conclusions:
- Autophagy plays a critical role in regulating vinorelbine sensitivity in lung adenocarcinoma cells.
- The study demonstrates that autophagy modulates vinorelbine sensitivity by maintaining Keap1-mediated ROS generation.
- Targeting autophagy in combination with chemotherapy could be a viable strategy to overcome drug resistance in lung cancer.
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