α-Lipoic acid prevents p53 degradation in colon cancer cells by blocking NF-κB induction of RPS6KA4

Tae Hyoung Yoo, Jin Hee Lee, Hyang Sook Chun, Sung-Gil Chi

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

α-Lipoic acid (α-LA) is a biogenic antioxidant that has been used successfully in the treatment of diabetic polyneuropathy and its application to many oxidative stress-associated chronic diseases has increased. In this study, we investigated the effect of α-LA on colorectal cancer cell growth and its underlying mechanism. α-LA treatment resulted in a marked reduction in the growth of HCT116 colon cancer cells in a dose-dependent manner through the G1 arrest of the cell cycle and apoptosis induction. α-LA treatment significantly increased tumor cell response to various apoptotic stresses, such as etoposide, 5-fluorouracil, UVC, γ-irradiation, hypoxia, and tumor necrosis factor α (TNFα). Interestingly, α-LA increased p53 protein stability and its apoptosis-enhancing effect was more evident in wild-type p53-carrying cells compared with p53-deficient cells, suggesting that the proapoptotic role of α-LA is associated with its p53-stabilizing function. On the basis of our microarray data showing α-LA downregulation of the ribosomal protein p90S6K (RPS6KA4), which has been reported to inhibit p53 function, we tested whether α-LA regulation of RPS6KA4 is associated with its proapoptotic function. α-LA treatment led to a marked reduction in the RPS6KA4 mRNA level in multiple colorectal cancer cells and restoration of RPS6KA4 expression markedly attenuated α-LA induction of apoptosis in a p53-dependent manner. In addition, we observed that RPS6KA4 expression is activated by TNFα whereas both basal and TNFα induction of RPS6KA4 are inhibited by the nuclear factor-κB (NF-κB) inhibitor BAY11-7082 or transfection of a dominant-negative mutant of NF-κB, indicating that NF-κB plays a crucial role in RPS6KA4 gene expression. Finally, we found that α-LA exerts an inhibitory effect on the nuclear translocation of NF-κB triggered by TNFα. Collectively, our study shows that α-LA suppresses colorectal tumor cell growth at least partially by preventing RPS6KA4-mediated p53 inhibition through blockade of NF-κB signaling.

Original languageEnglish
Pages (from-to)555-565
Number of pages11
JournalAnti-Cancer Drugs
Volume24
Issue number6
DOIs
Publication statusPublished - 2013 Apr 22

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Thioctic Acid
Colonic Neoplasms
Tumor Necrosis Factor-alpha
Colorectal Neoplasms
Apoptosis
Growth
G1 Phase Cell Cycle Checkpoints
Diabetic Neuropathies
Protein Stability
Ribosomal Proteins
Etoposide
blocking factor
Fluorouracil
Transfection
Oxidative Stress
Chronic Disease
Down-Regulation
Antioxidants
Gene Expression
Messenger RNA

Keywords

  • α-Lipoic acid
  • apoptosis
  • colon cancer
  • p53
  • RPS6KA4

ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)
  • Cancer Research
  • Oncology

Cite this

α-Lipoic acid prevents p53 degradation in colon cancer cells by blocking NF-κB induction of RPS6KA4. / Yoo, Tae Hyoung; Lee, Jin Hee; Chun, Hyang Sook; Chi, Sung-Gil.

In: Anti-Cancer Drugs, Vol. 24, No. 6, 22.04.2013, p. 555-565.

Research output: Contribution to journalArticle

Yoo, Tae Hyoung ; Lee, Jin Hee ; Chun, Hyang Sook ; Chi, Sung-Gil. / α-Lipoic acid prevents p53 degradation in colon cancer cells by blocking NF-κB induction of RPS6KA4. In: Anti-Cancer Drugs. 2013 ; Vol. 24, No. 6. pp. 555-565.
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