Tanshinone I induces apoptosis and protective autophagy in human glioblastoma cells via a reactive oxygen species‑dependent pathway

The mechanisms of tanshinone in the treatment of tumors

Tanshinone is a lipophilic compound that is present in traditional Chinese medicine and is derived from the roots of Salvia miltiorrhiza (Danshen). It has been proven to be highly effective in combating tumors in various parts of the body, including liver carcinoma, gastric cancer, ovarian cancer, cervix carcinoma, breast cancer, colon cancer, and prostate cancer. Tanshinone can efficiently prevent the reproduction of cancerous cells, induce cell death, and inhibit the spread of cancerous cells, which are mainly involved in the PI3K/Akt signaling pathway, NF-κB pathway, Bcl-2 family, Caspase cascades, MicroRNA, MAPK signaling pathway, p21, STAT3 pathway, miR30b-P53-PTPN11/SHP2 axis, β-catenin, and Skp2. However, the properties and mechanisms of tanshinone's anti-tumor effects remain unclear currently. Thus, this study aims to review the research progress on tumor prevention and mechanisms of tanshinone to gain new perspectives for further development and clinical application of tanshinone.

The enhanced cytotoxicity on breast cancer cells by Tanshinone I-induced photodynamic effect

Recently, natural photosensitizers, such as berberine, curcumin, riboflavin, and emodin, have received more and more attention in photodynamic therapy. Tanshinone I (TanI) is extracted from a traditional Chinese herb Danshen, and exhibits many physiological functions including antitumor. TanI is a photoactive phytocompounds, but no work was tried to investigate its potential photodynamic effect. This study evaluated the cytotoxicity induced by the photodynamic effect of TanI. The photochemical reactions of TanI were firstly investigated by laser flash photolysis. Then breast cancer cell line MDA-MB-231 was chosen as a model and the photodynamic effect of TanI on cancer cell was evaluated by MTT assay and flow cytometry. The results showed that TanI could be photoexcited by its UV-Vis absorption light to produce 3TanI* which was quickly quenched by O2. MTT assay showed that the photodynamic effect of TanI resulted in more obvious inhibitive effect on cell survival and cell migration. Besides, the photodynamic effect of TanI could induce cell apoptosis and necrosis, lead to cell cycle arrest in G2, increase intracellular ROS, and decrease the cellular Δψm. It can be concluded that the photodynamic effect of TanI can obviously enhance the cytotoxicity of TanI on MDA-MB-231 cells in vitro, which indicated that TanI might serve as a natural photosensitizer.

Enhanced Sestrin expression through Tanshinone 2A treatment improves PI3K-dependent inhibition of glioma growth

Glioblastomas are a highly aggressive cancer type which respond poorly to current pharmaceutical treatments, thus novel therapeutic approaches need to be investigated. One such approach involves the use of the bioactive natural product Tanshinone IIA (T2A) derived from the Chinese herb Danshen, where mechanistic insight for this anti-cancer agent is needed to validate its use. Here, we employ a tractable model system, Dictyostelium discoideum, to provide this insight. T2A potently inhibits cellular proliferation of Dictyostelium, suggesting molecular targets in this model. We show that T2A rapidly reduces phosphoinositide 3 kinase (PI3K) and protein kinase B (PKB) activity, but surprisingly, the downstream complex mechanistic target of rapamycin complex 1 (mTORC1) is only inhibited following chronic treatment. Investigating regulators of mTORC1, including PKB, tuberous sclerosis complex (TSC), and AMP-activated protein kinase (AMPK), suggests these enzymes were not responsible for this effect, implicating an additional molecular mechanism of T2A. We identify this mechanism as the increased expression of sestrin, a negative regulator of mTORC1. We further show that combinatory treatment using a PI3K inhibitor and T2A gives rise to a synergistic inhibition of cell proliferation. We then translate our findings to human and mouse-derived glioblastoma cell lines, where both a PI3K inhibitor (Paxalisib) and T2A reduces glioblastoma proliferation in monolayer cultures and in spheroid expansion, with combinatory treatment significantly enhancing this effect. Thus, we propose a new approach for cancer treatment, including glioblastomas, through combinatory treatment with PI3K inhibitors and T2A.

Recent advances of tanshinone in regulating autophagy for medicinal research

Initially described as an ancient and highly conserved catabolic biofunction, autophagy plays a significant role in disease pathogenesis and progression. As the bioactive ingredient of Salvia miltiorrhiza, tanshinone has recently shown profound effects in alleviating and treating various diseases by regulating autophagy. However, compared to the remarkable achievements in the known pharmacological effects of this traditional Chinese medicine, there is a lack of a concise and comprehensive review deciphering the mechanism by which tanshinone regulates autophagy for medicinal research. In this context, we concisely review the advances of tanshinone in regulating autophagy for medicinal research, including human cancer, the nervous system, and cardiovascular diseases. The pharmacological effects of tanshinone targeting autophagy involve the regulation of autophagy-related proteins, such as Beclin-1, LC3-II, P62, ULK1, Bax, ATG3, ATG5, ATG7, ATG9, and ATG12; the regulation of the PI3K/Akt/mTOR, MEK/ERK/mTOR, Beclin-1-related, and AMPK-related signaling pathways; the accumulation of reactive oxygen species (ROS); and the activation of AMPK. Notably, we found that tanshinone played a dual role in human cancers in an autophagic manner, which may provide a new avenue for potential clinical application. In brief, these findings on autophagic tanshinone and its derivatives provide a new clue for expediting medicinal research related to tanshinone compounds and autophagy.

Tanshinone I Mitigates Steroid-Induced Osteonecrosis of the Femoral Head and Activates the Nrf2 Signaling Pathway in Rats

Steroid-induced osteonecrosis of the femoral head (SIONFH) is a frequent orthopedic disease caused by long-term or high-dose administration of corticosteroids. Tanshinone I (TsI), a flavonoid compound isolated from Salvia miltiorrhiza Bunge, has been reported to inhibit osteoclastic differentiation in vitro. This study aimed to investigate whether TsI can ameliorate SIONFH. Herein, SIONFH was induced by intraperitoneal injection of 20 μg/kg lipopolysaccharide every 24 h for 2 days, followed by an intramuscular injection of 40 mg/kg methylprednisolone every 24 h for 3 days. Four weeks after the final injection of methylprednisolone, the rats were intraperitoneally administrated with low-dose (5 mg/kg) and high-dose (10 mg/kg) TsI once daily for 4 weeks. Results showed that TsI significantly alleviated osteonecrotic lesions of the femoral heads as determined by micro-CT analysis. Furthermore, TsI increased alkaline phosphatase activity and expressions of osteoblastic markers including osteocalcin, type I collagen, osteopontin, and Runt-related transcription factor 2 and decreased tartrate-resistant acid phosphatase activity and expressions of osteoclastic markers including cathepsin K and acid phosphatase 5. TsI also reduced inflammatory response and oxidative stress and activated the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway in the femoral heads. Taken together, our findings show that TsI can relieve SIONFH, indicating that it may be a candidate for preventing SIONFH.

Endoplasmic Reticulum Stress Contributed to Dipyridamole-Induced Impaired Autophagic Flux and Glioma Apoptosis

Elevation of intracellular cAMP levels has been implicated in glioma cell proliferation inhibition, differentiation, and apoptosis. Inhibition of phosphodiesterase is a way to elevate intracellular cAMP levels. The present study aimed to investigate the anti-glioma potential of dipyridamole, an inhibitor of phosphodiesterase. Upon treatment with dipyridamole, human U87 glioma cells decreased cell viability, clonogenic colonization, migration, and invasion, along with Noxa upregulation, Endoplasmic Reticulum (ER) stress, impaired autophagic flux, Yes-associated Protein 1 (YAP1) phosphorylation, and YAP1 reduction. Pharmacological and genetic studies revealed the ability of dipyridamole to initiate Noxa-guided apoptosis through ER stress. Additionally, the current study further identified the biochemical role of YAP1 in communicating with ER stress and autophagy under situations of dipyridamole treatment. YAP1 promoted autophagy and protected glioma cells from dipyridamole-induced apoptotic cell death. Dipyridamole impaired autophagic flux and rendered glioma cells more vulnerable to apoptotic cell death through ER stress-inhibitable YAP1/autophagy axis. The overall cellular changes caused by dipyridamole appeared to ensure a successful completion of apoptosis. Dipyridamole also duplicated the biochemical changes and apoptosis in glioma T98G cells. Since dipyridamole has additional biochemical and pharmacological properties, further research centered on the anti-glioma mechanisms of dipyridamole is still needed.

Medicinal Plants for Glioblastoma Treatment

Glioblastoma, an aggressive brain cancer, demonstrates the least life expectancy among all brain cancers. Because of the regulation of diverse signaling pathways in cancers, the chemotherapeutic approaches used to suppress their multiplication and spreading are restricted. Sensitivity towards chemotherapeutic agents has developed because of the pathological and drug-evading abilities of these diverse mechanisms. As a result, the identification and exploration of strategies or treatments, which can overcome such refractory obstacles to improve glioblastoma response to treatment as well as recovery, is essential. Medicinal herbs contain a wide variety of bioactive compounds, which could trigger aggressive brain cancers, regulate their anti-cancer mechanisms and immune responses to assist in cancer elimination, and cause cell death. Numerous tumor-causing proteins, which facilitate invasion as well as metastasis of cancer, tolerance of chemotherapies, and angiogenesis, are also inhibited by these phytochemicals. Such herbs remain valuable for glioblastoma prevention and its incidence by effectively being used as anti-glioma therapies. This review thus presents the latest findings on medicinal plants using which the extracts or bioactive components are being used against glioblastoma, their mechanism of functioning, pharmacological description as well as recent clinical studies conducted on them.

Alantolactone suppresses the metastatic phenotype and induces the apoptosis of glioblastoma cells by targeting LIMK kinase activity and activating the cofilin/G‑actin signaling cascade

Glioblastoma (GBM) is the most common aggressive brain tumor and is associated with an extremely poor prognosis, as the current standard of care treatments have limited efficacy. Natural compounds have attracted increasing attention as potential anticancer drugs. Alantolactone (ATL) is a natural small molecule inhibitor, that has antitumor properties. In the present study, U87MG and U251 cells were treated ATL and changes in actin/G-actin/F-actin/cofilin pathway were detected in whole cells, in the cytoplasm and mitochondria by western blot analysis. Immunofluorescence and immunoprecipitation analysis identified changes in the expression levels of target proteins and interactions, respectively. A LIMK enzyme inhibitor was also applied to assess the effects of ATL on the migration and invasion of GBM cells. Flow cytometry was used to detect the levels of apoptosis of GBM cells. The expression of matrix metalloproteinase (MMP)-2/MMP-9, caspase-3/caspase-9/poly(ADP-ribose) polymerase (PARP)/cytochrome c, were determined by western blot analysis to assess the effects of targeting LIMK. The in vitro findings were verified in vivo by characterizing changes in the expression of cofilin/LIMK in xenograft tumors in immunodeficient mice. It was found that ATL activated cofilin through the targeted inhibition of LIMK enzyme activity and it thus upregulated the ratio of G/F actin, and inhibited GBM cell migration and invasion. Conversely, the activation of cofilin and G-actin could be co-transferred to the mitochondria to initiate the mitochondrial-cytochrome c pathway to induce apoptosis. On the whole, the findings of the present study further illustrate the molecular mechanisms through which ATL inhibits the metastatic phenotype of GBM cells and induces apoptosis. Given previous findings, it can be deduced that ATL can function through multiple pathways and has multiple targets in GBM models, highlighting its potential for use in clinical applications.