Inhibition of SIRT1 signaling sensitizes the antitumor activity of silybin against human lung adenocarcinoma cells in vitro and in vivo

Anti-Tumor Activity and Mechanism of Silibinin Based on Network Pharmacology and Experimental Verification

Silibinin is a flavonoid compound extracted from the seeds of Silybum marianum (L.) Gaertn. It has the functions of liver protection, blood-lipid reduction and anti-tumor effects. However, the potential molecular mechanism of silibinin against tumors is still unknown. This study aimed to assess the anti-tumor effects of silibinin in adenoid cystic carcinoma (ACC2) cells and Balb/c nude mice, and explore its potential mechanism based on network pharmacology prediction and experimental verification. A total of 347 targets interacting with silibinin were collected, and 75 targets related to the tumor growth process for silibinin were filtrated. Based on the PPI analysis, CASP3, SRC, ESR1, JAK2, PRKACA, HSPA8 and CAT showed stronger interactions with other factors and may be the key targets of silibinin for treating tumors. The predicted target proteins according to network pharmacology were verified using Western blot analysis in ACC2 cells and Balb/c nude mice. In the pharmacological experiment, silibinin was revealed to significantly inhibit viability, proliferation, migration and induce the apoptosis of ACC2 cells in vitro, as well as inhibit the growth and development of tumor tissue in vivo. Western blot analysis showed that silibinin affected the expression of proteins associated with cell proliferation, migration and apoptosis, such as MMP3, JNK, PPARα and JAK. The possible molecular mechanism involved in cancer pathways, PI3K-Akt signaling pathway and viral carcinogenesis pathway via the inhibition of CASP3, MMP3, SRC, MAPK10 and CDK6 and the activation of PPARα and JAK. Overall, our results provided insight into the pharmacological mechanisms of silibinin in the treatment of tumors. These results offer a support for the anti-tumor uses of silibinin.

Additive pharmacological interaction between sirtuin inhibitor cambinol and paclitaxel in MCF7 luminal and MDA-MB-231 triple-negative breast cancer cells

Background

Breast cancer (BC) is the most common malignancy and the leading cause of cancer-related death in women worldwide. Sirtuin inhibitors (SIRTi), belonging to the histone deacetylase inhibitors group (HDIs), are potent epigenetic drugs that have been investigated for therapeutic use in different clinical disorders, including hematological malignancies and solid tumors.

Methods

The influence of cambinol (CAM; SIRTi) used individually or in combination with standard chemotherapeutic paclitaxel (PAX) on viability (MTT assay), proliferation (BrdU assay), induction of apoptosis and cell cycle arrest (FACS analysis) was determined in MCF7 luminal and MDA-MB-231 triple-negative breast cancer (TNBC) cells. The types of pharmacological drug–drug interaction between CAM and PAX were determined by an exact and rigorous pharmacodynamic method—an isobolography, to determine the presence of synergism, addition or antagonism between analyzed drugs using a variety of fixed-dose ratios.

Results

The combination of CAM and PAX at a fixed ratio of 1:1 exerted additive interaction in the viability of MCF7 and MDA-MB-231 BC cells. Both active agents used separately reduced viability and proliferation of BC cells as well as induced apoptosis and cell cycle arrest. These effects were much more evident in MCF7 than in MDA-MB-231 BC cells. Additionally, CAM combined with PAX increased anti-cancer activity compared to PAX used alone.

Conclusion

CAM might be considered a potential therapeutic agent individually or in combined therapy with PAX against luminal or TNBC.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s43440-022-00393-w.

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.

Lung Cancer Management with Silibinin: A Historical and Translational Perspective

The flavonolignan silibinin, the major bioactive component of the silymarin extract of Silybum marianum (milk thistle) seeds, is gaining traction as a novel anti-cancer therapeutic. Here, we review the historical developments that have laid the groundwork for the evaluation of silibinin as a chemopreventive and therapeutic agent in human lung cancer, including translational insights into its mechanism of action to control the aggressive behavior of lung carcinoma subtypes prone to metastasis. First, we summarize the evidence from chemically induced primary lung tumors supporting a role for silibinin in lung cancer prevention. Second, we reassess the preclinical and clinical evidence on the effectiveness of silibinin against drug resistance and brain metastasis traits of lung carcinomas. Third, we revisit the transcription factor STAT3 as a central tumor-cell intrinsic and microenvironmental target of silibinin in primary lung tumors and brain metastasis. Finally, by unraveling the selective vulnerability of silibinin-treated tumor cells to drugs using CRISPR-based chemosensitivity screenings (e.g., the hexosamine biosynthesis pathway inhibitor azaserine), we illustrate how the therapeutic use of silibinin against targetable weaknesses might be capitalized in specific lung cancer subtypes (e.g., KRAS/STK11 co-mutant tumors). Forthcoming studies should take up the challenge of developing silibinin and/or next-generation silibinin derivatives as novel lung cancer-preventive and therapeutic biomolecules.

Evaluation of Silibinin-Loaded Microbubbles Combined with Ultrasound in Ovarian Cancer Cells: Cytotoxicity and Mechanisms

BACKGROUND

The anticancer activity of silibinin (SB) has been demonstrated in various cancer cell types. However, its low solubility and poor bioavailability limit its clinical potential in biomedical applications. Microbubbles in combination with ultrasound are promising vehicles for local drug delivery.

OBJECTIVE

The present study determined the antitumour effects and molecular mechanism of silibinin-loaded microbubbles (SBMBs) in combination with ultrasound on ovarian cancer in vitro.

METHODS

SBMBs were prepared using mechanical vibration. The viability of A2780 cells was determined using the MTT assay. Flow cytometry was performed to detect cell apoptosis and the cell cycle. The expression of receptor tyrosine kinase (RTK)-associated downstream proteins was detected using multiplex assays and Western blots.

RESULTS

The present study designed and synthesized SBMBs. SBMBs in combination with ultrasound decreased A2780 cell viability in a dose- and time-dependent manner. The half maximal inhibitory concentration (IC50) showed that the cytotoxicity of the SBMBs was approximately 1.5 times greater than that of the SB in A2780 cells. SBMBs in combination with ultrasound resulted in significantly higher apoptosis efficiency compared to the SB group, and the SBMB population of cells was arrested in the G1/G0 phase. Further experiments demonstrated that SBMBs decreased the expression of signal transducer and activator of transcription 3 (STAT3), Ak strain transforming (AKT), and extracellular signal-regulated kinase (Erk) and had a greater effect than SB in A2780 cells. Inhibitors of AKT, Erk and STAT3 promoted the cytotoxicity of SBMBs.

CONCLUSION

SBMBs in combination with ultrasound may enhance the cytotoxicity efficiency of SB via the promotion of apoptosis and cell cycle arrest in ovarian cancer cells and the inactivation of the STAT3, AKT and Erk signalling pathways.

New Insights Toward Nanostructured Drug Delivery of Plant-Derived Polyphenol Compounds: Cancer Treatment and Gene Expression Profiles

The increasing prevalence of cancer has led to the expansion of traditional medicine objectives for developing novel drug delivery systems. A wide range of plant-derived polyphenol bioactive substances have been investigated in order to explore anti-cancer effects of these natural compounds and to promote effective treatment of cancer through apoptosis induction. In this regard, plant-derived polyphenol compounds including curcumin, silibinin, quercetin, and resveratrol have been the subject of intense interest for anti-cancer applications due to their ability in regulating apoptotic genes. However, some limitations of pure polyphenol compounds, such as poor bioavailability, short-term stability, low-cellular uptake, and insufficient solubility, have restricted their efficiency. Nanoscale formulations of bioactive agents have provided a novel platform to address these limitations. This paper reviews recent advances in nanoformulation approaches of polyphenolic drugs, and their effects on improving the delivery of chemotherapy agents to cancer cells.

Silibinin inhibited autophagy and mitochondrial apoptosis in pancreatic carcinoma by activating JNK/SAPK signaling

BACKGROUND

Previous investigation have indicated Silibinin induces apoptosis and JNK/SAPK in human pancreatic cancer cells. This study aims to evaluate the further mechanism of Silibinin in pancreatic cancer treatment.

MATERIALS AND METHODS

Human pancreatic cancer cell lines SW1990 was treated with Silibinin and/or JNK/SAPK inhibitor SP600125 followed by measurement of cell viability, apoptosis, autophagy, ROS and ATP, and western blotting.

RESULTS

Silibinin promoted cell viability and promoted cell apoptosis. The expression of ROS and ATP associated with mitochondrial function was also promoted by the treatment of silibinin. Silibinin also promoted autophagy in pancreatic cancer cells. All these biological effects of Silibinin can be reversed by JNK/SAPK inhibitor.

CONCLUSIONS

The biological effects regulated by Silibinin can be mediated by JNK/SAPK signaling. This provides a solid theoretical basis for the role of Silibinin in the treatment of pancreatic cancer.

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.

Traditional Chinese medicine as a cancer treatment: Modern perspectives of ancient but advanced science

Traditional Chinese medicine (TCM) has been practiced for thousands of years and at the present time is widely accepted as an alternative treatment for cancer. In this review, we sought to summarize the molecular and cellular mechanisms underlying the chemopreventive and therapeutic activity of TCM, especially that of the Chinese herbal medicine-derived phytochemicals curcumin, resveratrol, and berberine. Numerous genes have been reported to be involved when using TCM treatments and so we have selectively highlighted the role of a number of oncogene and tumor suppressor genes in TCM therapy. In addition, the impact of TCM treatment on DNA methylation, histone modification, and the regulation of noncoding RNAs is discussed. Furthermore, we have highlighted studies of TCM therapy that modulate the tumor microenvironment and eliminate cancer stem cells. The information compiled in this review will serve as a solid foundation to formulate hypotheses for future studies on TCM-based cancer therapy.

The anti-cancer effects and mechanisms of Scutellaria barbata D. Don on CL1-5 lung cancer cells

Lung cancer, with a poor prognosis and resistance to chemotherapy, is the most common malignant tumor and has the highest mortality rate worldwide. Scutellaria barbata D. Don (SB), which is derived from the dried whole plant of Labiatae, is a well-known anti-inflammatory and anti-cancer herb. The aim of this study was to examine the anti-cancer effects and precise regulatory mechanisms of SB in CL1-5 lung cancer cells. In an in vitro assay, we found that the anti-tumor mechanism of SB was due to P38/SIRT1-regulated cell apoptosis through G2/M phase arrest and ER stress-, intrinsic mitochondrial-, and extrinsic FAS/FASL-mediated pathways. Autophagy also plays a key role in SB-induced CL1-5 cell cytotoxicity. In addition, SB exerts additive effects with etoposide or cisplatin in lung cancer cells. In an in vivo assay, we found that SB significantly reduces tumor size with decreased proliferation and angiogenesis, as well as increased apoptosis and autophagy in CL1-5 tumor-bearing mice. These findings provided experimental evidence for the application of SB in the treatment of lung cancer.

Tumor-associated NADH oxidase (tNOX)-NAD+-sirtuin 1 axis contributes to oxaliplatin-induced apoptosis of gastric cancer cells

Oxaliplatin belongs to the platinum-based drug family and has shown promise in cancer treatment. The major mechanism of action of platinum compounds is to form platinum–DNA adducts, leading to DNA damage and apoptosis. Accumulating evidence suggests that they might also target non-DNA molecules for their apoptotic activity. We explored the effects of oxaliplatin on a tumor-associated NADH oxidase (tNOX) in gastric cancer lines. In AGS cells, we found that the oxaliplatin-inhibited tNOX effectively attenuated the NAD⁺/NADH ratio and reduced the deacetylase activity of an NAD⁺-dependent sirtuin 1, thereby enhancing p53 acetylation and apoptosis. Similar results were also observed in tNOX-knockdown AGS cells. In the more aggressive MKN45 and TMK-1 lines, oxaliplatin did not inhibit tNOX, and induced only minimal apoptosis and cytotoxicity. However, the downregulation of either sirtuin 1 or tNOX sensitized TMK-1 cells to oxaliplatin-induced apoptosis. Moreover, tNOX-depletion in these resistant cells enhanced spontaneous apoptosis, reduced cyclin D expression and prolonged the cell cycle, resulting in diminished cancer cell growth. Together, our results demonstrate that oxaliplatin targets tNOX and SIRT1, and that the tNOX-NAD⁺-sirtuin 1 axis is essential for oxaliplatin-induced apoptosis.

Prognostic and clinicopathological significance of SIRT1 expression in NSCLC: a meta-analysis

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer. The prognosis of NSCLC is extremely poor and it is urgently to find a new marker. Numerous studies have confirmed that silent mating type information regulation 2 homolog-1 (sirtuin1; SIRT1) is abnormally expressed in NSCLC. This meta-analysis was performed to investigate the prognostic and clinicopathological significance of SIRT1 in NSCLC. A total of seven eligible studies, including 6 on clinicopathological features, 7 on prognosis were identified from the databases. Pooled hazard ratios (HRs) or odds ratios (OR) and 95% confidence intervals (95% CIs) were calculated using random- or fixed-effects models. Results revealed that high expression of SIRT1 was associated with poor overall survival in NSCLC patients (HR=1.99, 95% CI: 1.33-2.98, P=0.0009). Moreover, SIRT1 were related to histological grade (OR= 2.00, 95% CI= 1.05–3.78, P= 0.02) of NSCLC patients. In conclusion, our present meta-analysis indicated that SIRT1 may serve as a promising marker for prognosis of patients with NSCLC.

β2-AR activation induces chemoresistance by modulating p53 acetylation through upregulating Sirt1 in cervical cancer cells

It has been suggested that β2‐adrenergic receptor (β2‐AR)‐mediated signaling induced by catecholamines regulates the degradation of p53. However, the underlying molecular mechanisms were not known. In the present study, we demonstrated that catecholamines upregulated the expression of silent information regulator 1 (Sirt1) through activating β2‐AR‐mediated signaling pathway, since selective β2‐AR antagonist ICI 118, 551 and non‐selective β‐blocker proprenolol effectively repressed isoproterenol (ISO)‐induced Sirt1 expression. Catecholamines inhibited doxorubicin (DOX)‐induced p53 acetylation and transcription‐activation activities by inducing the expression of Sirt1. Knockdown of the Sirt1 expression by the specific siRNA remarkably blocked the inhibitory effects of ISO on DOX‐induced p53 acetylation. In addition, we demonstrated that catecholamines induced resistance of cervical cancer cells to chemotherapeutics both in vitro and in vivo and that β2‐AR was overexpressed in cervical cancer tissues. Our data suggest that the p53‐dependent, chemotherapeutics‐induced cytotoxicity in cervical cancer cells may be compromised by catecholamines‐induced upregulation of the Sirt1 expression through activating the β2‐AR signaling.

[SIRT1 Influences the Sensitivity of A549 Non-small Cell Lung Cancer Cell Line to Cisplatin via Modulating the Noxa Expression]

背景与目的

非小细胞肺癌的顺铂耐药是常见的临床现象，严重制约了患者的化疗效果，是亟待解决的问题。SIRT1和Noxa的表达变化影响肿瘤细胞对化疗药物的敏感性。本研究旨在研究SIRT1表达对非小细胞肺癌对顺铂的敏感性的影响，并探讨其涉及Noxa表达的机制，以求为提高非小细胞肺癌细胞对顺铂敏感性提供希望。

方法

利用实时荧光定量PCR和Western blot分析A549细胞及顺铂耐药的A549/DDP细胞SIRT1及Noxa mRNA和蛋白水平的表达差异。利用siRNA干扰技术抑制A549/DDP细胞的SIRT1表达，进而使用Cell Titer Blue试验、流式细胞术从细胞增殖、细胞周期和细胞凋亡方面分析SIRT1沉默对A549/DPP细胞顺铂敏感性的影响。同时利用实时荧光定量PCR和Western blot分析SIRT1抑制对A549/DPP细胞Noxa表达的影响。

结果

A549细胞和A549/DDP细胞对顺铂的敏感性有显著差异，与A549细胞相比，A549/DDP细胞的SIRT1表达较高，但Noxa表达较低。使用siRNA抑制A549/DPP细胞的SIRT1表达后，与未抑制SIRT1细胞相比，4 μg/mL顺铂处理后的细胞存活率降低，G2期/M期阻滞比例增加，凋亡率提高。同时，SIRT1沉默导致A549/DPP细胞的Noxa表达增加。

结论

较高的SIRT1可能引起A549细胞对顺铂的耐药性，抑制SIRT1可以提高A549/DDP细胞对顺铂的敏感性，其机制可能涉及SIRT1对Noxa的调节。

Molecular and Cellular Changes During Cancer Progression Resulting From Genetic and Epigenetic Alterations

Tumorigenesis is a complex process that involves a persistent dismantling of cellular safeguards and checkpoints. These molecular and cellular changes that accumulate over months or decades lead to a change in the fundamental identity of a cell as it transitions from normal to malignant. In this chapter, we will examine some of the molecular changes in the evolving relationship between the genome and epigenome and highlight some of the key changes that occur as normal cells progress to tumor cells. For many years tumorigenesis was almost exclusively attributed to mutations in protein-coding genes. This notion that mutations in protein-coding genes were a fundamental driver of tumorigenesis enabled the development of several novel therapeutics that targeted the mutant protein or overactive pathway responsible for driving a significant portion of the tumor growth. However, because many therapeutic challenges remained in the face of these advances, it was clear that other pieces to the puzzle had yet to be discovered. Advances in molecular and genomics techniques continued and the study of epigenetics began to expand and helped reshape the view that drivers of tumorigenesis extended beyond mutations in protein-coding genes. Studies in the field of epigenetics began to identify aberrant epigenetic marks which created altered chromatin structures and enabled protein expression in tissues that defied rules governing tissue-specificity. Not only were epigenetic alterations found to enable overexpression of proto-oncogenes, they also led to the silencing of tumor suppressor genes. With these discoveries, it became clear that tumor growth could be stimulated by much more than mutations in protein-coding genes. In fact, it became increasingly clear that much of the human genome, while transcribed, did not lead to proteins. This discovery further led to studies that began to uncover the role of noncoding RNAs in regulating chromatin structure, gene transcription, and tumor biology. In this chapter, some of the key alterations in the genome and epigenome will be explored, and some of the cancer therapies that were developed as a result of these discoveries will be discussed.

Food-based natural products for cancer management: Is the whole greater than the sum of the parts?

The rise in cancer incidence and mortality in developing countries together with the human and financial cost of current cancer therapy mandates a closer look at alternative ways to overcome this burgeoning global healthcare problem. Epidemiological evidence for the association between cancer and diet and the long latency of most cancer progression have led to active exploration of whole and isolated natural chemicals from different naturally occurring substances in various preclinical and clinical settings. In general the lack of systemic toxicities of most 'whole' and 'isolated' natural compounds, their potential to reduce toxic doses and potential to delay the development of drug-resistance makes them promising candidates for cancer management. This review article examines the suggested molecular mechanisms affected by these substances focusing to a large extent on prostate cancer and deliberates on the disparate results obtained from cell culture, preclinical and clinical studies in an effort to highlight the use of whole extracts and isolated constituents for intervention. As such these studies underscore the importance of factors such as treatment duration, bioavailability, route of administration, selection criteria, standardized formulation and clinical end points in clinical trial design with both entities. Overall lack of parallel comparison studies between the whole natural products and their isolated compounds limits decisive conclusions regarding the superior utility of one over the other. We suggest the critical need for rigorous comparative research to identify which one of the two or both entities from nature would be best qualified to take on the mantle of cancer management.

Repositioning antipsychotic chlorpromazine for treating colorectal cancer by inhibiting sirtuin 1

Investigating existing drugs for repositioning can enable overcoming bottlenecks in the drug development process. Here, we investigated the effect and molecular mechanism of the antipsychotic drug chlorpromazine (CPZ) and identified its potential for treating colorectal cancer (CRC). Human CRC cell lines harboring different p53 statuses were used to investigate the inhibitory mechanism of CPZ. CPZ effectively inhibited tumor growth and induced apoptosis in CRC cells in a p53-dependent manner. Activation of c-jun N-terminal kinase (JNK) was crucial for CPZ-induced p53 expression and the subsequent induction of tumor apoptosis. Induction of p53 acetylation at lysine382 was involved in CPZ-mediated tumor apoptosis, and this induction was attenuated by sirtuin 1 (SIRT1), a class III histone deacetylase. By contrast, knocking down SIRT1 sensitized tumor cells to CPZ treatment. Moreover, CPZ induced the degradation of SIRT1 protein participating downstream of JNK, and JNK suppression abrogated CPZ-mediated SIRT1 downregulation. Clinical analysis revealed a significant association between high SIRT1 expression and poor outcome in CRC patients. These data suggest that SIRT1 is an attractive therapeutic target for CRC and that CPZ is a potential repositioned drug for treating CRC.

Silibinin: a potential old drug for cancer therapy

INTRODUCTION

Silibinin is mixture of flavonolignans extracted from milk thistle and often has been used in the treatment of acute and chronic liver disorders caused by toxins, drug, alcohol and hepatitis and gall bladder disorders for its antioxidant and hepatoprotective properties. Areas covered: However, increasing evidence suggest that silibinin is not solely limited in the treatment of these diseases. Further research suggests that silymarin may function diversely and may serve as a novel therapy for cancer therapy, such as lung cancer, prostatic cancer, colon cancer, breast cancer, bladder cancer and hepatocellular carcinoma by regulating cancer cells growth, proliferation, apoptosis, angiogenesis and many other mechanism. Expert commentary: In this review, in order to provide potential new treatment for these cancer, we summarize the recent anti-cancer findings of silibinin in these cancer and clarify the mechanisms of this effect.

Icariin displays anticancer activity against human esophageal cancer cells via regulating endoplasmic reticulum stress-mediated apoptotic signaling

In this study, we investigated the antitumor activity of icariin (ICA) in human esophageal squamous cell carcinoma (ESCC) in vitro and in vivo and explored the role of endoplasmic reticulum stress (ERS) signaling in this activity. ICA treatment resulted in a dose- and time-dependent decrease in the viability of human EC109 and TE1 ESCCs. Additionally, ICA exhibited strong antitumor activity, as evidenced by reductions in cell migration, adhesion, and intracellular glutathione (GSH) levels and by increases in the EC109 and TE1 cell apoptotic index, Caspase 9 activity, reactive oxygen species (ROS) level, and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity. Furthermore, ICA treatments upregulated the levels of ERS-related molecules (p-PERK, GRP78, ATF4, p-eIF2α, and CHOP) and a pro-apoptotic protein (PUMA) and simultaneously downregulated an anti-apoptotic protein (Bcl2) in the two ESCC cell lines. The downregulation of ERS signaling using eIF2α siRNA desensitized EC109 and TE1 cells to ICA treatment, and the upregulation of ERS signaling using thapsigargin sensitized EC109 and TE1 cells to ICA treatment. In summary, ERS activation may represent a mechanism of action for the anticancer activity of ICA in ESCCs, and the activation of ERS signaling may represent a novel therapeutic intervention for human esophageal cancer.

Novel Investigations of Flavonoids as Chemopreventive Agents for Hepatocellular Carcinoma

We would like to highlight the application of natural products to hepatocellular carcinoma (HCC). We will focus on the natural products known as flavonoids, which target this disease at different stages of hepatocarcinogenesis. In spite of the use of chemotherapy and radiotherapy in treating HCC, patients with HCC still face poor prognosis because of the nature of multidrug resistance and toxicity derived from chemotherapy and radiotherapy. Flavonoids can be found in many vegetables, fruits, and herbal medicines that exert their different anticancer effects via different intracellular signaling pathways and serve as antioxidants. In this review, we will discuss seven common flavonoids that exert different biological effects against HCC via different pathways.

Liver-targeting self-assembled hyaluronic acid-glycyrrhetinic acid micelles enhance hepato-protective effect of silybin after oral administration

In order to enhance oral bioavailability and liver targeting delivery of silybin, two amphiphilic hyaluronic acid derivatives, hyaluronic acid-deoxycholic acid (HA-adh-DOCA) and hyaluronic acid-glycyrrhetinic acid (HA-adh-GA) conjugates, were designed and synthesized. Silybin was successfully loaded in HA-adh-DOCA and HA-adh-GA micelles with high drug-loading capacities (20.3% ± 0.5% and 20.6% ± 0.6%, respectively). The silybin-loaded micelles were spherical in shape with the average size around 130 nm. In vitro release study showed that two silybin-loaded micelles displayed similar steady continued-release pattern in simulated gastrointestinal fluids and PBS. Single-pass intestinal perfusion studies indicated that silybin-loaded micelles were absorbed in the whole intestine and transported via a passive diffusion mechanism. Compared with suspension formulation, silybin-loaded HA-adh-DOCA and HA-adh-GA micelles achieved significantly higher AUC and Cmax level. Moreover, liver targeting drug delivery of micelles was confirmed by in vivo imaging analysis. In comparison between the two micellar formulations, HA-adh-GA micelles possessed higher targeting capacity than HA-adh-DOCA micelles, owing to the active hepatic targeting properties of glycyrrhetinic acid. In the treatment of acute liver injury induced by CCl4, silybin-loaded HA-adh-GA micelles displayed better effects over suspension control and silybin-loaded HA-adh-DOCA micelles. Overall, pharmaceutical and pharmacological indicators suggested that the HA-adh-GA conjugates can be successfully utilized for liver targeting of orally administered therapeutics.