Shikonin causes apoptosis by disrupting intracellular calcium homeostasis and mitochondrial function in human hepatoma cells

Abstract

Shikonin is known to suppress proliferation and induce apoptosis in a variety of cancer cell lines. In the present study, SMMC-7721 human hepatocellular carcinoma cells were treated with shikonin (1, 2 or 4 µM) for 12–48 h. Cell morphological alterations and DNA damage were determined. Furthermore, changes in cell cycle, mitochondrial transmembrane potential, calcium homeostasis and levels of reactive oxygen species were measured. Shikonin-treated SMMC-7721 cells exhibited morphological changes and DNA damage. Shikonin inhibited cell proliferation causing cell cycle arrest at the G0/G1 phase and induced apoptosis in a dose- and time-dependent manner. Shikonin-induced apoptosis was associated with activation of caspases-3, −8 and −9, elevated levels of intracellular Ca2+ and reactive oxygen species, reduced mitochondrial membrane potential and enhanced efflux of Ca2+ and K+. Gene expression B-cell lymphoma 2 (Bcl-2)-associated X protein (Bax), p53 and caspase-3 was up-regulated, whereas Bcl-2 expression was downregulated. Shikonin caused apoptosis by inhibiting cell cycle progression, disrupting Ca2+ homeostasis, inducing oxidative stress and triggering mitochondrial dysfunction. Activation of caspases-3, −8 and −9, K+ efflux, and regulation of Bax, Bcl-2, p53 and caspase-3 expression are involved in the process. These results provide in-depth insight into the mechanisms of action of shikonin in the treatment of cancer.

Phytochemical composition and bioactive effects of ethyl acetate fraction extract (EAFE) of Glechoma hederacea L.

“…Previous studies have shown that several plant extracts and active compounds induce caspase‐3‐mediated apoptotic cell death in hepatocellular carcinoma (Tang et al., 2020; Thakur & Devaraj, 2020). The pro‐apoptotic effect of shikonin is caused by the disruption of intracellular Ca 2+ homeostasis and mitochondrial dysfunction, activation of caspase‐3, caspase‐8, and caspase‐9 activities and regulation of Bcl‐2 family protein (Wang et al., 2018). One of the main active constituents of Stellera chamaejasme Linn.…”

Naturally occurring anti-cancer compounds: shining from Chinese herbal medicine

“…There are multiple mechanisms involved in the anticancer effects of shikonin, including ER stress, ROS generation, glutathione (GSH) depletion, mitochondrial membrane potential disruption, p53, superoxide dismutase (SOD) and Bax up-regulation, PARP cleavage, catalase and Bcl-2 down-regulation [591,[612][613][614]. The pro-apoptotic effect of shikonin is also caused by the disruption of intracellular Ca 2+ homeostasis and mitochondrial dysfunction, which involves enhanced Ca 2+ and potassium (K + ) efflux, caspase-3, -8 and -9 activation, and Bcl-2 family protein modulation [615,616]. ERK pathway also plays a role in shikonin-induced anti-cancer effects.…”

Fraxetin Suppresses Cell Proliferation and Induces Apoptosis through Mitochondria Dysfunction in Human Hepatocellular Carcinoma Cell Lines Huh7 and Hep3B

“…Changes in calcium ion levels in cell organelles are related to mitochondrial dysfunction and can cause apoptosis. For instance, intracellular calcium ion upregulation in human hepatoma cells is usually associated with oxidative stress and mitochondrial dysfunction, leading to antiproliferation and cell death [ 17 ]. The calcium levels in both the cytosol and mitochondrial matrix are involved in the progression of cancers including HCC [ 18 , 19 ].…”