Luteolin induces caspase-dependent apoptosis via inhibiting the AKT/osteopontin pathway in human hepatocellular carcinoma SK-Hep-1 cells.

Abstract

AIMS:

Luteolin, a naturally occurring flavonoid, possesses anti-cancer effects including induction of apoptosis. This study investigated the involvement of osteopontin (OPN) in luteolin-induced apoptosis in human hepatocellular carcinoma (HCC) SK-Hep-1 cells with high OPN expression.

MAIN METHODS:

MTT assay was used to determine the cell viability. Cell cycle analysis was performed to identify apoptosis. Apoptosis was confirmed by detecting cytoplasmic histone-associated-DNA-fragments using a cell death detection ELISAPLUS kit. The expression of proteins was evaluated by Western blot. Reverse transcriptase-polymerase chain reaction was employed to detect the expression of mRNA.

KEY FINDINGS:

Cytotoxic effect of luteolin was higher in cancer cell line SK-Hep-1 cells than in normal cell line AML12 cells. Luteolin led a significantly increase in apoptosis accompanied by activation of caspase 8, -9 and -3 and cleavage of poly (ADP-ribose) polymerase (PARP), which was completely blocked by Z-VAD-FMK, a pan caspase inhibitor. Luteolin significantly downregulated the expression of X-linked inhibitor of apoptosis (XIAP), Mcl-1 and Bid. Furthermore, luteolin effectively decreased OPN expression at both mRNA and protein level. Exogenous OPN markedly blocked apoptosis induction, caspases activation, PARP cleavage, downregulation of XIAP and Mcl-1 in luteolin-treated cells. Luteolin impaired the AKT pathway by inhibiting the phosphorylation of AKT. SC79, an AKT activator, blocked apoptosis induction, caspases activation, PARP cleavage, downregulation of OPN, XIAP, Mcl-1 and Bid in luteolin-treated cells.

SIGNIFICANCE:

These results demonstrated that luteolin inhibits the AKT/OPN pathway, thereby inducing caspase-dependent apoptosis in human HCC SK-Hep-1 cells with little toxicity.

• Authors: Eunji Im, Changhwan Yeo, Eun-Ok Lee
• Journal: Life sciences (Life Sci) Vol. 209 Pg. 259-266 (Sep 15 2018) ISSN: 1879-0631 [Electronic] Netherlands
• PMID: 30107166 (Publication Type: Journal Article)
• Copyright: Copyright © 2018 Elsevier Inc. All rights reserved.

Chemical References

• Biomarkers, Tumor
• Caspase Inhibitors
• SPP1 protein, human
• Osteopontin
• Poly(ADP-ribose) Polymerases
• Proto-Oncogene Proteins c-akt
• Caspases
• Luteolin

Topics

• Apoptosis (drug effects)
• Biomarkers, Tumor (genetics, metabolism)
• Carcinoma, Hepatocellular (drug therapy, genetics, metabolism, pathology)
• Caspase Inhibitors (pharmacology)
• Caspases (chemistry, metabolism)
• Cell Line, Tumor
• Cell Proliferation (drug effects)
• Gene Expression Regulation, Neoplastic (drug effects)
• Humans
• Liver Neoplasms (drug therapy, genetics, metabolism, pathology)
• Luteolin (pharmacology)
• Osteopontin (genetics, metabolism)
• Poly(ADP-ribose) Polymerases (genetics, metabolism)
• Proto-Oncogene Proteins c-akt (genetics, metabolism)
• Signal Transduction (drug effects)