Silybin suppresses cell proliferation and induces apoptosis of multiple myeloma cells via the PI3K/Akt/mTOR signaling pathway

A comprehensive review of the PTEN/PI3K/Akt axis in multiple myeloma: From molecular interactions to potential therapeutic targets

Phosphatase and tensin homolog (PTEN), phosphatidylinositol 3-kinase (PI3K), and protein kinase B (Akt) signaling pathways contribute to the development of several cancers, including multiple myeloma (MM). PTEN is a tumor suppressor that influences the PI3K/Akt/mTOR pathway, which in turn impacts vital cellular processes like growth, survival, and treatment resistance. The current study aims to present the role of PTEN and PI3K/Akt/mTOR signaling in the development of MM and its response to treatment. In addition, the molecular interactions in MM that underpin the PI3K/Akt/mTOR pathway and address potential implications for the development of successful treatment plans are also discussed in detail. We investigate their relationship to both upstream and downstream regulators, highlighting new developments in combined therapies that target the PTEN/PI3K/Akt axis to overcome drug resistance, including the use of PI3K and mitogen-activated protein kinase (MAPK) inhibitors. We also emphasize that PTEN/PI3K/Akt pathway elements may be used in MM diagnosis, prognosis, and therapeutic targets.

Anti-tumor effect of dandelion flavone on multiple myeloma cells and its mechanism

BACKGROUND

Multiple myeloma (MM) is a prevalent hematologic malignancy characterized by the uncontrolled proliferation of monoclonal plasma cells in the bone marrow and excessive monoclonal immunoglobulin production, leading to organ damage. Despite therapeutic advancements, recurrence and drug resistance remain significant challenges.

OBJECTIVE

This study investigates the effects of dandelion flavone (DF) on MM cell proliferation, migration, and invasion, aiming to elucidate the mechanisms involved in MM metastasis and to explore the potential of traditional Chinese medicine in MM therapy.

METHODS

DF's impact on myeloma cell viability was evaluated using the CCK-8 and colony formation assays. Cell mobility and invasiveness were assessed through wound healing and transwell assays, respectively. RT-PCR was employed to quantify mRNA levels of MMP-2, MMP-9, TIMP-1, and TIMP-2. Apoptotic rates and molecular markers were analyzed via flow cytometry and RT-PCR. The PI3K/AKT signaling pathway was studied using Western blot and ELISA, with IGF-1 and the PI3K inhibitor LY294002 used to validate the findings.

RESULTS

DF demonstrated dose-dependent inhibitory effects on MM cell proliferation, migration, and invasion. It reduced mRNA levels of MMP-2 and MMP-9 while increasing those of TIMP-1 and TIMP-2. Furthermore, DF enhanced the expression of pro-apoptotic proteins and inhibited M2 macrophage polarization by targeting key molecules and enzymes. The anti-myeloma activity of DF was mediated through the inhibition of the PI3K/AKT pathway, as evidenced by diminished phosphorylation and differential effects in the presence of IGF-1 and LY294002.

CONCLUSION

By modulating the PI3K/AKT pathway, DF effectively inhibits MM cell proliferation, migration, and invasion, and induces apoptosis, establishing a novel therapeutic strategy for MM based on traditional Chinese medicine.

Utilizing mixture design response surface methodology to determine effective combinations of plant derived compounds as prostate cancer treatments

BACKGROUND

Prostate cancer (PC) is estimated to cause 13.1% of all new cancer cases in the United States in 2021. Natural bioactive compounds have drawn the interest of researchers worldwide in their efforts to find novel treatments for PC. Many of these bioactive compounds have been identified from traditional Chinese medicine (TCM) remedies often containing multiple bioactive compounds. However, in vitro studies frequently focus on the compounds in isolation.

AIM

We used mixture design response surface methodology (MDRSM) to assess changes in PC cell viability after 48 h of treatment to identify the optimal mixture of all 35 three-compound combinations of seven bioactive compounds from TCM.

METHODS AND RESULTS

We used berberine, wogonin, shikonin, curcumin, triptolide, emodin, and silybin to treat PC3 and LNCaP human PC cells at their IC50 concentrations that we calculated. These compounds modulate many chemotherapeutic pathways including intrinsic and extrinsic apoptosis, increasing reactive oxygen species, decreasing metastatic pathways, inhibiting cell cycle progression. We hypothesize that because these compounds bind to unique molecular targets to activate different chemotherapeutic pathways, they will act synergistically to decrease tumor cell viability. Results from MDRSM showed that two-way combinations were more effective than three-way or single compounds. Most notably wogonin, silybin, emodin and berberine responded well in two-compound combinations with each other in PC3 and LNCaP cells. We then conducted cell viability tests combining two bioactive compound ratios with docetaxel (Doc) and found significant results within the LNCaP cell line. In particular, mixtures of berberine and wogonin, berberine and silybin, emodin and berberine, and emodin and silybin reduced LNCaP cell viability up to an average of 90.02%. The two-compound combinations were significantly better than docetaxel treatment of LNCaP cells.

CONCLUSION

Within the PC3 cells, we show that a combination of berberine, wogonin and docetaxel is just as effective as docetaxel alone. Thus, we provide new combination treatments that are highly effective in vitro for treating androgen-dependent and androgen-independent PC.

Mechanistic Insights into the Pharmacological Significance of Silymarin

Medicinal plants are considered the reservoir of diverse therapeutic agents and have been traditionally employed worldwide to heal various ailments for several decades. Silymarin is a plant-derived mixture of polyphenolic flavonoids originating from the fruits and akenes of Silybum marianum and contains three flavonolignans, silibinins (silybins), silychristin and silydianin, along with taxifolin. Silybins are the major constituents in silymarin with almost 70–80% abundance and are accountable for most of the observed therapeutic activity. Silymarin has also been acknowledged from the ancient period and is utilized in European and Asian systems of traditional medicine for treating various liver disorders. The contemporary literature reveals that silymarin is employed significantly as a neuroprotective, hepatoprotective, cardioprotective, antioxidant, anti-cancer, anti-diabetic, anti-viral, anti-hypertensive, immunomodulator, anti-inflammatory, photoprotective and detoxification agent by targeting various cellular and molecular pathways, including MAPK, mTOR, β-catenin and Akt, different receptors and growth factors, as well as inhibiting numerous enzymes and the gene expression of several apoptotic proteins and inflammatory cytokines. Therefore, the current review aims to recapitulate and update the existing knowledge regarding the pharmacological potential of silymarin as evidenced by vast cellular, animal, and clinical studies, with a particular emphasis on its mechanisms of action.

Resibufogenin inhibits the malignant characteristics of multiple myeloma cells by blocking the PI3K/Akt signaling pathway

Resibufogenin (RBG) is an active ingredient of toad venom that also has antitumor potential. The present study aimed to investigate the role of RBG in multiple myeloma (MM) and the underlying action mechanism involving the PI3K/Akt signaling pathway. A human MM cell line, RPMI8226, was treated with RBG and/or insulin-like growth factor 1 (IGF-1; an activator of the PI3K/AKT signaling pathway). Cell viability and apoptosis were detected using Cell Counting Kit-8 and flow cytometry, respectively. Cell migration and invasion were detected using a Transwell assay. In addition, the epithelial-mesenchymal transition (EMT)-associated proteins (E-cadherin, N-cadherin and Vimentin) and the PI3K/AKT pathway-associated proteins [AKT, phosphorylated (p)-AKT, PI3K and p-PI3K] were measured using western blotting. RBG inhibited the viability, migration and invasion, and promoted the apoptosis of RPMI8226 cells in a dose-dependent manner. RBG at concentrations of 4 and 8 µM upregulated E-cadherin, and downregulated N-cadherin and Vimentin in RPMI8226 cells. RBG also decreased the protein expression of p-AKT and p-PI3K in a dose-dependent manner. In addition, the intervention of IGF-1 weakened the inhibitory effects of RBG on the malignant characteristics of MM cells. RBG-induced inhibition of EMT and the PI3K/AKT pathway were also weakened by IGF-1 treatment. In conclusion, RBG inhibited viability, migration, invasion and EMT, and promoted the apoptosis of MM cells by blocking the PI3K/AKT signaling pathway.

Role of Silymarin in Cancer Treatment: Facts, Hypotheses, and Questions

The flavonoid silymarin extracted from the seeds of Sylibum marianum is a mixture of 6 flavolignan isomers. The 3 more important isomers are silybin (or silibinin), silydianin, and silychristin. Silybin is functionally the most active of these compounds. This group of flavonoids has been extensively studied and they have been used as hepato-protective substances for the mushroom Amanita phalloides intoxication and mainly chronic liver diseases such as alcoholic cirrhosis and nonalcoholic fatty liver. Hepatitis C progression is not, or slightly, modified by silymarin. Recently, it has also been proposed for SARS COVID-19 infection therapy. The biochemical and molecular mechanisms of action of these substances in cancer are subjects of ongoing research. Paradoxically, many of its identified actions such as antioxidant, promoter of ribosomal synthesis, and mitochondrial membrane stabilization, may seem protumoral at first sight, however, silymarin compounds have clear anticancer effects. Some of them are: decreasing migration through multiple targeting, decreasing hypoxia inducible factor-1α expression, inducing apoptosis in some malignant cells, and inhibiting promitotic signaling among others. Interestingly, the antitumoral activity of silymarin compounds is limited to malignant cells while the nonmalignant cells seem not to be affected. Furthermore, there is a long history of silymarin use in human diseases without toxicity after prolonged administration. The ample distribution and easy accessibility to milk thistle-the source of silymarin compounds, its over the counter availability, the fact that it is a weed, some controversial issues regarding bioavailability, and being a nutraceutical rather than a drug, has somehow led medical professionals to view its anticancer effects with skepticism. This is a fundamental reason why it never achieved bedside status in cancer treatment. However, in spite of all the antitumoral effects, silymarin actually has dual effects and in some cases such as pancreatic cancer it can promote stemness. This review deals with recent investigations to elucidate the molecular actions of this flavonoid in cancer, and to consider the possibility of repurposing it. Particular attention is dedicated to silymarin's dual role in cancer and to some controversies of its real effectiveness.

Function of selected natural antidiabetic compounds with potential against cancer via modulation of the PI3K/AKT/mTOR cascade

Diabetes mellitus (DM) is a metabolic disorder with growing global incidence, as 387 million people were diagnosed in 2014 with an expected projection of 642 million in 2040. Several complications are associated with DM including heart attack, stroke, kidney failure, blindness, and cancer. The latter is the second leading cause of death worldwide accounting for one in every six deaths, with liver, pancreas, and endometrium cancers are the most abundant among patients with diabetes. Phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) pathway plays a vital role in developing a wide array of pathological disorders, among them diabetes and cancer. Natural secondary metabolites that counteract the deleterious effects of reactive oxygen species (ROS) and modulate PI3K/Akt/mTOR pathway could be a promising approach in cancer therapy. Here, 717 medicinal plants with antidiabetic activities were highlighted along with 357 bioactive compounds responsible for the antidiabetic activity. Also, 43 individual plant compounds with potential antidiabetic activities against cancer via the modulation of PI3K/Akt/mTOR cascade were identified. Taken together, the available data give an insight of the potential of repurposing medicinal plants and/or the individual secondary metabolites with antidiabetic activities for cancer therapy.

Phosphatidylinositol 3-kinase signaling inhibitors for treatment of multiple myeloma: From small molecules to microRNAs

Multiple myeloma is one of the most hard-to-treat cancers among blood malignancies due to the high rate of drug resistance and relapse. The researchers are trying to find more effective drugs for treatment of the disease. Hence, the use of drugs targeting signaling pathways has become a powerful weapon. Overactivation of phosphatidylinositol 3-kinase signaling pathways is frequently observed in multiple myeloma cancer cells, which increases survival, proliferation, and even drug resistance in such cells. In recent years, drugs that inhibit the mediators involved in this biological pathway have shown promising results in the treatment of multiple myeloma. In the present study, we aimed to introduce phosphatidylinositol 3-kinase signaling inhibitors which include small molecules, herbal compounds, and microRNAs.

Phytochemicals in cancer and their effect on the PI3K/AKT-mediated cellular signalling

Protein kinases belong to the largest family of enzymes controlling every aspect of cellular activity including gene expression, cell division, differentiation and metabolism. They are part of major intracellular signalling pathways. Hence, it is not surprising that they are involved in the development of major diseases such as cardiovascular disorders, diabetes, dementia and, most importantly, cancer when they undergo mutations, modifications and unbalanced expression. This review will explore the possibility to draw a connection between the application of natural phytochemicals and the treatment of cancer. We have chosen to focus on the PI3K/AKT cellular signalling pathway which has been shown to be a major target by natural compounds in cell cultures and animal models.

Osr1 regulates hepatic inflammation and cell survival in the progression of non-alcoholic fatty liver disease

Odd-skipped related 1 (Osr1) is a novel tumor suppressor gene in several cancer cell lines. Non-alcoholic steatohepatitis (NASH) is considered as a high-risk factor for hepatocellular carcinoma (HCC). This study is aimed to investigate the novel role of Osr1 in promoting the progression of hepatic steatosis to NASH. Following 12 weeks of diethylnitrosamine (DEN) and high-fat diet (HFD), wildtype (WT) and Osr1 heterozygous (Osr1+/-) male mice were examined for liver injuries. Osr1+/- mice displayed worsen liver injury with higher serum alanine aminotransferase levels than the WT mice. The Osr1+/- mice also revealed early signs of collagen deposition with increased hepatic Tgfb and Fn1 expression. There was overactivation of both JNK and NF-κB signaling in the Osr1+/- liver, along with accumulation of F4/80+ cells and enhanced hepatic expression of Il-1b and Il-6. Moreover, the Osr1+/- liver displayed hyperphosphorylation of AKT/mTOR signaling, associated with overexpression of Bcl-2. In addition, Osr1+/- and WT mice displayed differences in the DNA methylome of the liver cells. Specifically, Osr1-responsible CpG islands of Ccl3 and Pcgf2, genes for inflammation and macrophage infiltration, were further identified. Taken together, Osr1 plays an important role in regulating cell inflammation and survival through multiple signaling pathways and DNA methylation modification for NAFLD progression.

Health Benefits of Silybum marianum: Phytochemistry, Pharmacology, and Applications

Silybum marianum (SM), a well-known plant used as both a medicine and a food, has been widely used to treat various diseases, especially hepatic diseases. The seeds and fruits of SM contain a flavonolignan complex called silymarin, the active compounds of which include silybin, isosilybin, silychristin, dihydrosilybin, silydianin, and so on. In this review, we thoroughly summarize high-quality publications related to the pharmacological effects and underlying mechanisms of SM. SM has antimicrobial, anticancer, hepatoprotective, cardiovascular-protective, neuroprotective, skin-protective, antidiabetic, and other effects. Importantly, SM also counteracts the toxicities of antibiotics, metals, and pesticides. The diverse pharmacological activities of SM provide scientific evidence supporting its use in both humans and animals. Multiple signaling pathways associated with oxidative stress and inflammation are the common molecular targets of SM. Moreover, the flavonolignans of SM are potential agonists of PPARγ and ABCA1, PTP1B inhibitors, and metal chelators. At the end of the review, the potential and perspectives of SM are discussed, and these insights are expected to facilitate the application of SM and the discovery and development of new drugs. We conclude that SM is an interesting dietary medicine for health enhancement and drug discovery and warrants further investigation.

Silymarin inhibited DU145 cells by activating SLIT2 protein and suppressing expression of CXCR4

Among other cancers, prostate cancer is globally the second most rampant one with the incidence of 29.4% among men. SLIT2/ROBO1 signaling is very crucial pathway causally implicated in many cancers and reported to inhibit a variety of cancer cell types. CXCR4 is a chemokine receptor implicated in cancer progression. Silymarin is a phytochemical, of which anti-carcinogenic activity was suggested in various cancers, including prostate cancer. However, there are no studies examining the effect of silymarin on SLIT2-Robo1-CXCR4 axis. Herein, our goal is to explore cytotoxic and morphological effects of silymarin on DU145 cells and to reveal its role in Slit2/Robo and CXCR1 pathway. First, 24, 48 and 72 h-long cytotoxicity tests were performed for dose analysis of silymarin, followed H-E stain for morphological evaluation with varying doses of silymarin. Afterward, western blot and immunocytochemistry analyses were carried out for SLIT2, ROBO1 and CXCR4 proteins. According to MTT analysis, IC50 concentrations for silymarin were 315, 126 and 70 µM against DU145 cells for 24, 48 and 72 h treatments. In H-E, several apoptotic hallmarks, including, condensed, kidney-shaped and eccentric nuclei, membrane blebbings and apoptotic body formations were observed. Silymarin increased the expressions of SLIT2 and ROBO1 while decreased CXCR4 when compared to control group in immunocytochemistry and Western blot. To summarize, silymarin inhibited DU145 cells dose-dependently by activating SLIT2 protein and inhibiting expression of CXCR4. This study is the first examining the interplay between Slit2-Robo1-CXCR4 proteins and silymarin in DU145 cells. We believe that our study will provide new insights for future studies.

Effects of cyclophosphamide on the phenotypes and functions of THP-1 cells

Early and accurate evaluation of immunotoxicity is crucial. However, there are few in vitro models for immunosuppressive evaluation. THP-1 cells has long been used for in vitro sensitivity evaluation. Whether it can be used for immunosuppressive evaluation remains unclear. In this study, effects of immunosuppressant cyclophosphamide (CY) on THP-1 cells were observed while 2, 4-Dinitrochlorobenzene (DNCB) was used as a control. The phenotypes of THP-1 cells, the ability to activate naïve T cells, intracellular reactive oxygen species (ROS) level, gene markers, phagocytic ability and cell apoptosis were detected after THP-1 cells being exposed to different concentrations of CY and DNCB. Both CY and DNCB were able to activate THP-1 cells, but there were a lot of differences in their effects on THP-1 cells, such as the changes in phenotypes, in the ability to activate naïve T cells, in ROS production and in marker gene expression. Firstly, CY down-regulated the expression of CD86 on THP-1 cells while DNCB up-regulated its expression. Secondly, the ability of THP-1 cells to activate naïve T cells was enhanced by CY and suppressed by DNCB. Thirdly, CY raised rapid and transient elevation of ROS level in THP-1 cells, while the effects of DNCB were slower and longer-lasting. Finally, only CY could lead to an increase in heme oxygenase 1 (HMOX1) expression. Taken all these results into account, we suggested that THP-1 cell line possesses the potency to be an in vitro model of immunosuppressive evaluation. And the surface molecule CD86, the ability to activate naïve T cells, the ROS production and the gene marker HMOX1 of THP-1 cells are promising markers.

Apoptotic Pathway as the Therapeutic Target for Anticancer Traditional Chinese Medicines

Cancer is a leading cause of morbidity and mortality worldwide. Apoptosis is a process of programmed cell death and it plays a vital role in human development and tissue homeostasis. Mounting evidence indicates that apoptosis is closely related to the survival of cancer and it has emerged as a key target for the discovery and development of novel anticancer drugs. Various studies indicate that targeting the apoptotic signaling pathway by anticancer drugs is an important mechanism in cancer therapy. Therefore, numerous novel anticancer agents have been discovered and developed from traditional Chinese medicines (TCMs) by targeting the cellular apoptotic pathway of cancer cells and shown clinically beneficial effects in cancer therapy. This review aims to provide a comprehensive discussion for the role, pharmacology, related biology, and possible mechanism(s) of a number of important anticancer TCMs and their derivatives mainly targeting the cellular apoptotic pathway. It may have important clinical implications in cancer therapy.

Future of Personalized Therapy Targeting Aberrant Signaling Pathways in Multiple Myeloma

Multiple myeloma (MM) is a genetically complex disease. Identification of mutations and aberrant signaling pathways that contribute to the progression of MM and drug resistance has potential to lead to specific targets and personalized treatment. Aberrant signal pathways include RAS pathway activation due to RAS or BRAF mutations (targeted by vemurafenib alone or combined with cobimetinib), BCL-2 overexpression in t(11:14) (targeted by venetoclax), JAK2 pathway activation (targeted by ruxolitinib), NF-κB pathway activation (treated with DANFIN combined with bortezomib), MDM2 overexpression, and PI3K/mTOR pathway activation (targeted by BEZ235). Cyclin D1 (CCND1) and MYC are also emerging as key potential targets. In addition, histone deacetylase inhibitors are already in use for the treatment of MM in combination therapy, and targeted inhibition of FGFR3 (AZD4547) is effective in myeloma cells with t(4;14) translocation. Bromodomain and extra terminal (BET) protein antagonists decrease the expression of MYC and have displayed promising antimyeloma activity. A better understanding of the alterations in signaling pathways that promote MM progression will further inform the development of precision therapy for patients.

Association analysis between feed efficiency and expression of key genes of the avTOR signaling pathway in meat-type ducks

Genes involved in the target of rapamycin (TOR) signaling pathway are implicated in nutrient translation, cell proliferation and differentiation, and anabolism, which can affect both growth and feed intake. However, the role of TOR signaling in the regulation of feed intake and feed efficiency in poultry is not clear. In the present study, a total of 1000 ducks, of similar initial weight, were chosen and transferred to individual cages to determine their residual feed intake (RFI) from the age of 21 to 42 days. Subsequently, 60 ducks, which were divided into high (HRFI) and low (LRFI) groups according to their RFI, were chosen to analyze the TOR signaling activities in the liver. The differential expression level of genes involved in the TOR signaling pathway was assayed by the real-time polymerase chain reaction. In the liver, the expression of AKT, avTOR, avLST8, and S6K1 was significantly higher in LRFI ducks than in HRFI ducks; avTOR and AKT were negatively associated with the feed conversion ratio and RFI. Furthermore, PI3K was moderately positively associated with AKT; AKT was strongly positively associated with PI3K, avTOR, avLST8, and S6K1; and avTOR was strongly positively associated with S6K1. In conclusion, the activation of avTOR signaling in the liver of LRFI ducks might be ascribed to higher energy state or more active nutrient transport (amino acids), or both, than those in the liver of HRFI ducks. The results of the present study indicate that AKT and avTOR of TOR signaling might be used as candidate genes to assess molecular regulation of feed efficiency.

Hematopoietic-substrate-1 associated protein X-1 (HAX-1) regulates liver cancer cells growth, metastasis, and angiogenesis through Akt

The aim of this study was to investigate the effects and mechanisms of hematopoietic-substrate-1-associated protein X-1 (HAX-1) on liver cancer cells. Information on HAX-1 from liver cancer patients was analyzed by the Cancer Genome Atlas (TCGA) program. Cell migration and invasion abilities were respectively tested by scratch assay and transwell assay. Tube formation assay was applied to detect angiogenesis protein and mRNA was determined using quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot. We found that the median month survival of HAX-1 overexpressing liver cancer patients was shorter than that of HAX-1 normal liver cancer patients. HAX-1 was overexpressed in liver cancer tissues and cells, and HAX-1 overexpression promoted the liver cancer cells growth, migration, and invasion, whereas silencing HAX-1 produced the opposite results. Inhibition of Akt by LY294002 reversed the migration and invasion abilities of liver cancer cells, and inhibited the ability of cells growth and angiogenesis. Silencing PIK3CA enhanced the inhibitory effects of HAX-1 silencing on the viability, migration, and invasion of liver cancer cells. HAX-1 affected liver cancer cells metastasis and angiogenesis by affecting Akt phosphorylation and FOXO3A expression.

Autophagy induced by cardamonin is associated with mTORC1 inhibition in SKOV3 cells

BACKGROUND

The mammalian target of rapamycin (mTOR) integrates energy level to modulate cell proliferation and autophagy. Cardamonin exhibits anti-proliferative activity through inhibiting mTOR. In this study, the effect of cardamonin on autophagy and its mechanism on mTOR inhibition were investigated.

METHODS

Cell viability and proliferation were measured by MTT assay and BrdU incorporation, respectively. Cell apoptosis was assayed by flow cytometry and cell autophagy was detected by electron microscopy and GFP-LC3 fluorescence. The mechanism of cardamonin on mTORC1 inhibition was investigated by Raptor siRNA and Raptor over-expression.

RESULTS

The cell viability and proliferation were inhibited by cardamonin. The autophagosomes and the protein level of LC3-II were increased by cardamonin. Cell apoptosis and the levels of cleaved PARP and Caspase-3 were increased by cardamonin. Cardamonin inhibited the phosphorylation of mTOR and ribosome S6 protein kinase 1 (S6K1) as well as the protein level of regulatory associated protein of mTOR (Raptor). However, cardamonin had no effect on the component of mTORC2 and its downstream substrate Akt. The inhibitory effect of cardamonin on the phosphorylation of mTOR and S6K1 was eliminated by Raptor knockdown with siRNA, whereas this effect of cardamonin was stronger than that of rapamycin and AZD8055 in Raptor over-expression cells. Cell viability was inhibited by cardamonin in both Raptor knockdown and Raptor over-expression cells, which was consistent with the inhibitory effect of cardamonin on mTOR.

CONCLUSION

These findings demonstrated that the autophagy induced by cardamonin was associated with mTORC1 inhibition through decreasing the protein level of Raptor in SKOV3 cells.

Silibinin Induced Human Glioblastoma Cell Apoptosis Concomitant with Autophagy through Simultaneous Inhibition of mTOR and YAP

Silibinin, also known as silybin, is the major flavonolignan isolated from Silybum marianum. Although previous reports demonstrated that silibinin exhibits significant tumor suppressor activities in various cancers by promoting cell apoptosis, it was also shown to trigger autophagy to counteract apoptosis induced by exogenous stresses in several types of cells. However, there is no report to address the role of silibinin induced autophagy in human A172 and SR glioblastoma cells. Our study showed that silibinin treatment not only inhibited the metabolic activities of glioblastoma cells but also promoted their apoptosis through the regulation of caspase 3 and PARP-1 in concentration- and time-dependent manners. Meanwhile, silibinin induced autophagy through upregulation of microtubule-associated protein a light chain 3- (LC3-) II. And autophagy inhibition with chloroquine, a lysosomotropic agent, significantly enhanced silibinin induced glioblastoma cell apoptosis. Moreover, silibinin dose-dependently downregulated the phosphorylation levels of mTOR at Ser-2448, p70S6K at Thr-389, and 4E-BP1 at Thr-37/46. Furthermore, the expression of YAP, the downstream effector of Hippo signal pathway, was also suppressed by silibinin. These results suggested that silibinin induced glioblastoma cell apoptosis concomitant with autophagy which might be due to simultaneous inhibition of mTOR and YAP and silibinin induced autophagy exerted a protective role against cell apoptosis in both A172 and SR cells.

Combining the mammalian target of rapamycin inhibitor, rapamycin, with resveratrol has a synergistic effect in multiple myeloma

Rapamycin is known to inhibit the mammalian target of rapamycin complex (mTORC)1 signaling pathway, but it is unable to effectively inhibit mTORC2, resulting in activation of protein kinase B in multiple myeloma (MM) cell lines. Additionally, certain studies have suggested that resveratrol has an effect on human MM cells, and that rapamycin in combination with resveratrol may be useful in cancer therapy. The present study aimed to investigate the combined treatment effect of resveratrol and rapamycin on the MM MM1.S cell line. The results demonstrated that combined treatment with rapamycin and resveratrol effectively inhibited cell viability in the MM1.S cell line through inhibition of the mTORC1 and mTORC2 signaling pathways, compared with resveratrol or rapamycin monotherapy. In addition, cyclin D1 levels were decreased and the activation of caspase-3 and poly (ADP-ribose) polymerase was increased. These results suggested that downregulation of the mTOR signaling cascades is likely to be a crucial mediator in the impairment of viability and the induction of apoptosis resulting from combined therapy with resveratrol and rapamycin in MM1.S cells.

Silibinin inhibits migration and invasion of the rhabdoid tumor G401 cell line via inactivation of the PI3K/Akt signaling pathway

Rhabdoid tumors, which tend to occur prior to the age of 2 years, are one of the most aggressive malignancies and have a poor prognosis due to the frequency of metastasis. Silibinin, a natural extract, has been approved as a potential tumor suppressor in various studies, however, whether or not it also exerts its antitumor capacity in rhabdoid tumors, particularly with regards to tumor migration and invasion, is unclear. The rhabdoid tumor G401 cell line was used in the present in vitro study. An MTT assay was used to assess the cytotoxicity of silibinin on G401 cells, cell migration was studied using a wound healing assay and a Transwell migration assay, and cell invasion was determined using a Transwell invasion assay. The underlying mechanism in silibinin inhibited cell migration and invasion was investigated by western blot analysis and further confirmed using a specific inhibitor. Experimental results demonstrated that high doses of silibinin suppressed cell viability, and that low doses of silibinin inhibited cell migration and invasion without affecting cell proliferation. The phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signaling pathway was involved in the silibinin-induced inhibition of metastasis. Silibinin inactivated the PI3K/Akt pathway, and inhibited cell migration and invasion, an effect that was further enhanced when LY294002, a classic PI3K inhibitor, was used concurrently. In general, silibinin inhibits migration and invasion of the rhabdoid tumor G401 cell line via inactivation of the PI3K/Akt signaling pathway and may be a potential chemotherapeutic drug to combat rhabdoid tumors in the future.

Downregulation of TM7SF4 inhibits cell proliferation and metastasis of A549 cells through regulating the PI3K/AKT/mTOR signaling pathway

Lung cancer is one of the most common types of malignant tumor worldwide. The etiology of lung cancer is complex and, although significant progress has been made in previous investigations, the molecular mechanism responsible for lung cancer remains to be fully elucidated. In the present study, the association between lung cancer and transmembrane 7 superfamily member 4 (TM7SF4) was investigated. Reverse transcription‑quantitative polymerase chain reaction technology was used to detect the expression of TM7SF4, and it was expressed at a high level in lung cancer. Furthermore, by overexpressing and inhibiting the expression of TM7SF4, the present study compared cell proliferation and migration rates. It was confirmed that TM7SF4 promoted lung cancer cell proliferation and migration. TM7SF4 was also confirmed to promote cancer cell migration and invasion by modulating the activation of the phosphatidylinositol 3‑kinase/Akt pathway in the A549 cells. Correspondingly, the inhibition of TM7SF4 decreased the expression of proteins associated with AKT, whereas the overexpression of TM7SF4 promoted the expression of the relevant proteins. Therefore, the present study confirmed that TM7SF4 was involved in the progression of lung cancer via regulating the activation of AKT. These findings suggested that TM7SF4 may be involved in the progression of lung cancer and may be a novel therapeutic target for this disease.

Silibinin: an old drug for hematological disorders

Introduction

Silibinin (silybin), a non-toxic natural polyphenolic flavonoid, is the principal and the most biologically active component of silymarin. It is efficient in the treatment of acute and chronic liver disorders caused by toxins, drug, alcohol, hepatitis, and gall bladder disorders. Further, in our previous studies, we explored the anti-cancer efficacy in common cancers, such as lung, prostatic, colon, breast, bladder, as well as, hepatocellular carcinoma. Interestingly, silibinin is still not solely limited to the treatment of these diseases. Recent research endeavors suggest that silibinin may function diversely and serve as a novel therapy for hematological disorders.

Areas covered

It discovered several interesting viewpoints in the widely studied mechanisms of silibinin in the hematological disorders.

Expert commentary

In this report, we review the up-to-date findings of more potency roles of silibinin in β-thalassemia (β-TM), acute myeloid leukemia (AML), anaplastic large cell lymphoma (ALCL) and multiple myelomas (MM) therapy and attempt to clarify the mechanisms underlying its effects. There are two viewpoints: First, The functional mechanisms of silibinin in AML cells via regulating cell differentiation to exert anti-cancer effect; Second, combination treatment strategy may be a good choice.

Anticancer efficacy of the ethyl acetate extract from the traditional Chinese medicine herb Celastrus orbiculatus against human gastric cancer

ETHNOPHARMACOLOGICAL RELEVANCE

The traditional Chinese medicine (TCM) herb Celastrus orbiculatus is an important folk medicinal plant in China that has been used as an anti-inflammatory, antitumor, and analgesic in various diseases. The ethyl acetate extract of C. orbiculatus (C. orbiculatus extract, COE) was reported to show significant antitumor effects. However, no study in China or abroad has reported the effect and mechanism of COE in triggering apoptosis of gastric cancer (GC) cells.

AIM OF STUDY

To further uncover the molecular mechanism underlying COE's apoptotic and anti-proliferative effects and lay a foundation for the development of novel, effective antitumor TCM agents.

MATERIALS AND METHODS

The effect of COE on AGS and BGC-823 GC cell viability was examined using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis of AGS and BGC-823 cells induced by COE was analyzed using flow cytometry and a mitochondrial membrane potential assay kit (JC-1). The proliferating GC cells were identified and examined using a 5-bromo-2'-deoxyuridine (BrdU) staining kit and flow cytometric analysis. A western blot assay was used to detect the effect of COE on apoptosis-related proteins, B-cell lymphoma-2 (Bcl-2), Bcl-extra-large (Bcl-xL), Bcl-2-like protein 12 (Bcl-L12), Bcl-2-associated X protein (Bax), and caspase as well as proliferation-related proteins, phosphoinositide 3-kinase (PI3K)/Akt/mechanistic target of rapamycin (mTOR)/p70s6k. Transmission electron microscopy (TEM) and an animal imaging technique were used to evaluate the microstructure of apoptotic GC cells and the effect of COE on tumor cell growth in vivo, respectively.

RESULTS

The results indicate that COE significantly inhibited proliferation and induced apoptosis of GC AGS and BGC-823 cell lines both in vivo and in vitro. COE significantly decreased the cell mitochondrial membrane potential. Moreover, COE downregulated the levels of Bcl-2, Bcl-xL, and PI3K/Akt/mTOR/p70s6k while those of Bax and caspase were upregulated. More interestingly, COE altered the microstructure of the mitochondria.

CONCLUSION

All these data collectively indicate that COE not only has significant antiproliferative effects but also has both in vivo and in vitro apoptotic effects. In addition, COE altered the structure and function of the mitochondria, which is another potential pathway for the antitumor activity of COE. These findings may provide a basis for the development of new anticancer TCM candidates.

Comprehensive analysis of the long noncoding RNA HOXA11-AS gene interaction regulatory network in NSCLC cells

Background

Long noncoding RNAs (lncRNAs) are related to different biological processes in non-small cell lung cancer (NSCLC). However, the possible molecular mechanisms underlying the effects of the long noncoding RNA HOXA11-AS (HOXA11 antisense RNA) in NSCLC are unknown.

Methods

HOXA11-AS was knocked down in the NSCLC A549 cell line and a high throughput microarray assay was applied to detect changes in the gene profiles of the A549 cells. Bioinformatics analyses (gene ontology (GO), pathway, Kyoto Encyclopedia of Genes and Genomes (KEGG), and network analyses) were performed to investigate the potential pathways and networks of the differentially expressed genes. The molecular signatures database (MSigDB) was used to display the expression profiles of these differentially expressed genes. Furthermore, the relationships between the HOXA11-AS, de-regulated genes and clinical NSCLC parameters were verified by using NSCLC patient information from The Cancer Genome Atlas (TCGA) database. In addition, the relationship between HOXA11-AS expression and clinical diagnostic value was analyzed by receiver operating characteristic (ROC) curve.

Results

Among the differentially expressed genes, 277 and 80 genes were upregulated and downregulated in NSCLC, respectively (fold change ≥2.0, P < 0.05 and false discovery rate (FDR) < 0.05). According to the degree of the fold change, six upregulated and three downregulated genes were selected for further investigation. Only four genes (RSPO3, ADAMTS8, DMBT1, and DOCK8) were reported to be related with the development or progression of NSCLC based on a PubMed search. Among all possible pathways, three pathways (the PI3K-Akt, TGF-beta and Hippo signaling pathways) were the most likely to be involved in NSCLC development and progression. Furthermore, we found that HOXA11-AS was highly expressed in both lung adenocarcinoma and squamous cell carcinoma based on TCGA database. The ROC curve showed that the area under curve (AUC) of HOXA11-AS was 0.727 (95% CI 0.663–0.790) for lung adenocarcinoma and 0.933 (95% CI 0.906–0.960) for squamous cell carcinoma patients. Additionally, the original data from TCGA verified that ADAMTS8, DMBT1 and DOCK8 were downregulated in both lung adenocarcinoma and squamous cell carcinoma, whereas RSPO3 expression was upregulated in lung adenocarcinoma and downregulated in lung squamous cell carcinoma. For the other five genes (STMN2, SPINK6, TUSC3, LOC100128054, and C8orf22), we found that STMN2, TUSC3 and C8orf22 were upregulated in squamous cell carcinoma and that STMN2 and USC3 were upregulated in lung adenocarcinoma. Furthermore, we compared the correlation between HOXA11-AS and de-regulated genes in NSCLC based on TCGA. The results showed that the HOXA11-AS expression was negatively correlated with DOCK8 in squamous cell carcinoma (r = −0.124, P = 0.048) and lung adenocarcinoma (r = −0.176, P = 0.005). In addition, RSPO3, ADAMTS8 and DOCK8 were related to overall survival and disease-free survival (all P < 0.05) of lung adenocarcinoma patients in TCGA.

Conclusions

Our results showed that the gene profiles were significantly changed after HOXA11-AS knock-down in NSCLC cells. We speculated that HOXA11-AS may play an important role in NSCLC development and progression by regulating the expression of various pathways and genes, especially DOCK8 and TGF-beta pathway. However, the exact mechanism should be verified by functional experiments.