Cellular and Molecular Neurobiology

, Volume 37, Issue 3, pp 555–562 | Cite as

RLIP76 Depletion Enhances Autophagic Flux in U251 Cells

Original Research
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Abstract

Our previous study showed that RalA-binding protein 1 (RLIP76) is overexpressed in gliomas and is associated with higher tumour grade and decreased patient survival. Furthermore, RLIP76 downregulation increases chemosensitivity of glioma cells to temozolomide by inducing apoptosis. However, other mechanisms underlying RLIP76-associated chemoresistance are unknown. In this study, we investigated the effect of RLIP76 depletion on autophagy. RLIP76 was knocked down in U251 glioma cells using shRNA and autophagy-related proteins, and PI3K/Akt signalling components were evaluated. RLIP76 depletion significantly increased cell autophagy as demonstrated by a significant increase in LC3 II, autophagy protein 5 (ATG-5), and Beclin1, and a decrease in p62 expression levels. Furthermore, RLIP76 knockdown increased autophagic flux in U251 cells as autolysosome numbers increased relative to autophagosome numbers. Autophagy induced by RLIP76 knockdown resulted in increased apoptosis that was independent of temozolomide treatment. Moreover, RLIP76 knockdown decreased PI3K and Akt activation. RLIP76 depletion also resulted in decreased levels of the anti-apoptotic protein Bcl2. LY294002, a PI3K/Akt pathway inhibitor, led to increased autophagy and apoptosis in U251 RLIP76-depleted cells. Therefore, RLIP76 knockdown increased autophagic flux and apoptosis in U251 glioma cells, possibly through inhibition of the PI3K/Akt pathway. Thus, this study provides a novel mechanism for the role of RLIP76 in glioma pathogenesis and chemoresistance.

Keywords

RLIP76 PI3K–Akt Glioma Autophagy Apoptosis 
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Notes

Acknowledgments

This work was generously supported by the National Natural Sciences Fund Project of China (NSFC Nos. 81500601), Shanghai Municipal Natural Science Foundation (14ZR1413800) and Shanghai Municipal Health Bureau Project (201440383 and 20154Y0036).

Compliance with Ethical Standards

Conflict of Interest

The authors declare that they do not have any financial or non-financial competing interests.

Supplementary material

10571_2016_410_MOESM1_ESM.pdf (901 kb)
Supplementary material 1 (PDF 900 kb)
10571_2016_410_MOESM2_ESM.pdf (91 kb)
Supplementary material 2 (PDF 90.8 kb)

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Copyright information

© Springer Science+Business Media New York 2016

Authors and Affiliations

  1. 1.Department of Neurosurgery, Changzheng HospitalSecond Military Medical UniversityShanghaiChina
  2. 2.Department of Pediatric Neurosurgery, Xinhua Hospital, School of MedicineShanghai Jiao Tong UniversityShanghaiChina
  3. 3.Department of NeurosurgeryPLA No. 322 HospitalShanxiChina
  4. 4.Department of Cardiology, Ren Ji Hospital, School of MedicineShanghai Jiao Tong UniversityShanghaiChina

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