Brusatol, a Nrf2 Inhibitor Targets STAT3 Signaling Cascade in Head and Neck Squamous Cell Carcinoma

Flaming the fight against cancer cells: the role of microRNA-93

There have been attempts to develop novel anti-tumor drugs in cancer therapy. Although satisfying results have been observed at a consequence of application of chemotherapeutic agents, the cancer cells are capable of making resistance into these agents. This has forced scientists into genetic manipulation as genetic alterations are responsible for generation of a high number of cancer cells. MicroRNAs (miRs) are endogenous, short non-coding RNAs that affect target genes at the post-transcriptional level. Increasing evidence reveals the potential role of miRs in regulation of biological processes including angiogenesis, metabolism, cell proliferation, cell division, and cell differentiation. Abnormal expression of miRs is associated with development of a number of pathologic events, particularly cancer. MiR-93 plays a significant role in both physiological and pathological mechanisms. At the present review, we show how this miR dually affects the proliferation and invasion of cancer cells. Besides, we elucidate the oncogenesis or oncosuppressor function of miR-93.

MicroRNAs in cancer therapy: Their involvement in oxaliplatin sensitivity/resistance of cancer cells with a focus on colorectal cancer

The resistance of cancer cells into chemotherapy has restricted the efficiency of anti-tumor drugs. Oxaliplatin (OX) being an anti-tumor agent/drug is extensively used in the treatment of various cancer diseases. However, its frequent application has led to chemoresistance. As a consequence, studies have focused in finding underlying molecular pathways involved in OX resistance. MicroRNAs (miRs) are short endogenous non-coding RNAs that are able to regulate vital biological mechanisms such as cell proliferation and cell growth. The abnormal expression of miRs occurs in pathological events, particularly cancer. In the present review, we describe the involvement of miRs in OX resistance and sensitivity. The miRs are able to induce the oncogene factors and mechanisms, resulting in stimulation OX chemoresistance. Also, onco-suppressor miRs can enhance the sensitivity of cancer cells into OX chemotherapy and trigger apoptosis and cell cycle arrest, leading to reduced viability and progression of cancer cells. MiRs can also enhance the efficacy of OX chemotherapy. It is worth mentioning that miRs affect various down-stream targets in OX resistance/sensitivity such as STAT3, TGF-β, ATG4B, FOXO1, LATS2, NF-κB and so on. By identification of these miRs and their upstream and down-stream mediators, further studies can focus on targeting them to sensitize cancer cells into OX chemotherapy and induce apoptotic cell death.

Targeting the JAK/STAT Signaling Pathway Using Phytocompounds for Cancer Prevention and Therapy

Cancer is a prevalent cause of mortality around the world. Aberrated activation of Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathway promotes tumorigenesis. Natural agents, including phytochemicals, exhibit potent anticancer activities via various mechanisms. However, the therapeutic potency of phytoconstituents as inhibitors of JAK/STAT signaling against cancer has only come into focus in recent days. The current review highlights phytochemicals that can suppress the JAK/STAT pathway in order to impede cancer cell growth. Various databases, such as PubMed, ScienceDirect, Web of Science, SpringerLink, Scopus, and Google Scholar, were searched using relevant keywords. Once the authors were in agreement regarding the suitability of a study, a full-length form of the relevant article was obtained, and the information was gathered and cited. All the complete articles that were incorporated after the literature collection rejection criteria were applied were perused in-depth and material was extracted based on the importance, relevance, and advancement of the apprehending of the JAK/STAT pathway and their relation to phytochemicals. Based on the critical and comprehensive analysis of literature presented in this review, phytochemicals from diverse plant origins exert therapeutic and cancer preventive effects, at least in part, through regulation of the JAK/STAT pathway. Nevertheless, more preclinical and clinical research is necessary to completely comprehend the capability of modulating JAK/STAT signaling to achieve efficient cancer control and treatment.

Versatile role of curcumin and its derivatives in lung cancer therapy

Lung cancer is a main cause of death all over the world with a high incidence rate. Metastasis into neighboring and distant tissues as well as resistance of cancer cells to chemotherapy demand novel strategies in lung cancer therapy. Curcumin is a naturally occurring nutraceutical compound derived from Curcuma longa (turmeric) that has great pharmacological effects, such as anti-inflammatory, neuroprotective, and antidiabetic. The excellent antitumor activity of curcumin has led to its extensive application in the treatment of various cancers. In the present review, we describe the antitumor activity of curcumin against lung cancer. Curcumin affects different molecular pathways such as vascular endothelial growth factors, nuclear factor-κB (NF-κB), mammalian target of rapamycin, PI3/Akt, microRNAs, and long noncoding RNAs in treatment of lung cancer. Curcumin also can induce autophagy, apoptosis, and cell cycle arrest to reduce the viability and proliferation of lung cancer cells. Notably, curcumin supplementation sensitizes cancer cells to chemotherapy and enhances chemotherapy-mediated apoptosis. Curcumin can elevate the efficacy of radiotherapy in lung cancer therapy by targeting various signaling pathways, such as epidermal growth factor receptor and NF-κB. Curcumin-loaded nanocarriers enhance the bioavailability, cellular uptake, and antitumor activity of curcumin. The aforementioned effects are comprehensively discussed in the current review to further direct studies for applying curcumin in lung cancer therapy.

Inhibitory effects of brusatol delivered using glycosaminoglycan‑placental chondroitin sulfate A‑modified nanoparticles on the proliferation, migration and invasion of cancer cells

Breakthroughs in cancer management result from the development of drugs that can be used for early diagnosis and effective treatment. Surgery, chemotherapy, radiotherapy and hormone therapy are the main anticancer therapies. However, traditional cancer chemotherapy is associated with serious systemic side effects. Nanoparticles (NPs) provide an effective solution for cancer treatment via the targeted delivery of drugs to cancer cells, while minimizing injury to normal cells. Glycosaminoglycan-placental chondroitin sulfate A (plCSA) is expressed in a number of tumor cells and trophoblasts. A plCSA-binding peptide (plCSA-BP) was isolated from malaria protein VAR2CSA, which can effectively promote the binding of lipid polymer NPs to tumor cells, thereby significantly enhancing the anticancer effect of encapsulated drugs. Brusatol is an important compound derived from Brucea javanica that exerts a multitude of biological effects, including inhibiting tumor cell growth, reducing the reproduction of malaria parasites, reducing inflammation and resisting virus invasion. In the present study, brusatol-loaded NPs (BNPs) or coumarin 6 NPs (CNPs), plCSA-BP and scrambled control peptide-bound BNPs or CNPs were prepared. Ovarian cancer cells (SKOV3), endometrial cancer cells (HEC-1-A) and lung cancer cells (A549) were treated with the NPs. The uptake of plCSA-CNPs by tumor cells was found to be markedly higher compared with that of other types of NPs. Further studies demonstrated that the plCSA-BNPs promoted the apoptosis of cancer cells more effectively and inhibited their proliferation, invasion and migration, accompanied by downregulation of matrix metalloproteinase (MMP)-2, MMP-9 and B-cell CLL/lymphoma 2 (BCL2) levels, but upregulation of BCL2-associated X protein BAX and cleaved caspase-3 levels. The results demonstrated the potential of brusatol delivered by plCSA-modified NPs as a chemotherapeutic agent for the targeted therapy of tumors by regulating the BCL2, BAX, cleaved caspase-3, MMP-2 and MMP-9 pathways, and indicated that it may be an effective and safe strategy for the treatment of various tumors.

The role of natural products in revealing NRF2 function

Covering: up to 2020The transcription factor NRF2 is one of the body's major defense mechanisms, driving transcription of >300 antioxidant response element (ARE)-regulated genes that are involved in many critical cellular processes including redox regulation, proteostasis, xenobiotic detoxification, and primary metabolism. The transcription factor NRF2 and natural products have an intimately entwined history, as the discovery of NRF2 and much of its rich biology were revealed using natural products both intentionally and unintentionally. In addition, in the last decade a more sinister aspect of NRF2 biology has been revealed. NRF2 is normally present at very low cellular levels and only activated when needed, however, it has been recently revealed that chronic, high levels of NRF2 can lead to diseases such as diabetes and cancer, and may play a role in other diseases. Again, this "dark side" of NRF2 was revealed and studied largely using a natural product, the quassinoid, brusatol. In the present review, we provide an overview of NRF2 structure and function to orient the general reader, we will discuss the history of NRF2 and NRF2-activating compounds and the biology these have revealed, and we will delve into the dark side of NRF2 and contemporary issues related to the dark side biology and the role of natural products in dissecting this biology.

Anticancer effects of brusatol in nasopharyngeal carcinoma through suppression of the Akt/mTOR signaling pathway

PURPOSE

Brusatol, a natural quassinoid that is isolated from a traditional Chinese herbal medicine known as Bruceae Fructus, possesses biological activity in various types of human cancers, but its effects in nasopharyngeal carcinoma (NPC) have not been reported. This study aimed to explore the effect and molecular mechanism of brusatol in NPC in vivo and in vitro.

METHODS

The antiproliferative effect of brusatol was assessed by MTT and colony formation assays. Apoptosis was determined by flow cytometry. The expression of mitochondrial apoptosis, cell cycle arrest, and Akt/mTOR pathway proteins were determined by western blot analysis. Further in vivo confirmation was performed in a nude mouse model.

RESULTS

Brusatol showed antiproliferative activity against four human NPC cell lines (CNE-1, CNE-2, 5-8F, and 6-10B) in a dose-dependent manner. This antiproliferative effect was accompanied by mitochondrial apoptosis and cell cycle arrest through the modulation of several key molecular targets, such as Bcl-xl, Bcl-2, Bad, Bax, PARP, Caspase-9, Caspase-7, Caspase-3, Cdc25c, Cyclin B1, Cdc2 p34, and Cyclin D1. In addition, we found that brusatol inhibited the activation of Akt, mTOR, 4EBP1, and S6K, suggesting that the Akt/mTOR pathway is a key underlying mechanism by which brusatol inhibits growth and promotes apoptosis. Further in vivo nude mouse models proved that brusatol significantly inhibited the growth of CNE-1 xenografts with no significant toxicity.

CONCLUSIONS

These observations indicate that brusatol is a promising antitumor drug candidate or a supplement to current chemotherapeutic therapies to treat NPC.

Modulation of STAT3 Signaling, Cell Redox Defenses and Cell Cycle Checkpoints by β-Caryophyllene in Cholangiocarcinoma Cells: Possible Mechanisms Accounting for Doxorubicin Chemosensitization and Chemoprevention

Cholangiocarcinoma (CCA) is an aggressive group of biliary tract cancers, characterized by late diagnosis, low effective chemotherapies, multidrug resistance, and poor outcomes. In the attempt to identify new therapeutic strategies for CCA, we studied the antiproliferative activity of a combination between doxorubicin and the natural sesquiterpene β-caryophyllene in cholangiocarcinoma Mz-ChA-1 cells and nonmalignant H69 cholangiocytes, under both long-term and metronomic schedules. The modulation of STAT3 signaling, oxidative stress, DNA damage response, cell cycle progression and apoptosis was investigated as possible mechanisms of action. β-caryophyllene was able to synergize the cytotoxicity of low dose doxorubicin in Mz-ChA-1 cells, while producing cytoprotective effects in H69 cholangiocytes, mainly after a long-term exposure of 24 h. The mechanistic analysis highlighted that the sesquiterpene induced a cell cycle arrest in G2/M phase along with the doxorubicin-induced accumulation in S phase, reduced the γH2AX and GSH levels without affecting GSSG. ROS amount was partly lowered by the combination in Mz-ChA-1 cells, while increased in H69 cells. A lowered expression of doxorubicin-induced STAT3 activation was found in the presence of β-caryophyllene in both cancer and normal cholangiocytes. These networking effects resulted in an increased apoptosis rate in Mz-ChA-1 cells, despite a lowering in H69 cholangiocytes. This evidence highlighted a possible role of STAT3 as a final effector of a complex network regulated by β-caryophyllene, which leads to an enhanced doxorubicin-sensitivity of cholangiocarcinoma cells and a lowered chemotherapy toxicity in nonmalignant cholangiocytes, thus strengthening the interest for this natural sesquiterpene as a dual-acting chemosensitizing and chemopreventive agent.

Evodiamine Mitigates Cellular Growth and Promotes Apoptosis by Targeting the c-Met Pathway in Prostate Cancer Cells

Evodiamine (EVO) is an indoloquinazoline alkaloid that exerts its various anti-oncogenic actions by blocking phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt), mitogen-activated protein kinase (MAPK), c-Met, and nuclear factor kappa B (NF-κB) signaling pathways, thus leading to apoptosis of tumor cells. We investigated the ability of EVO to affect hepatocyte growth factor (HGF)-induced c-Met/Src/STAT3 activation cascades in castration-resistant prostate cancer (CRPC). First, we noted that EVO showed cytotoxicity and anti-proliferation activities in PC-3 and DU145 cells. Next, we found that EVO markedly inhibited HGF-induced c-Met/Src/STAT3 phosphorylation and impaired the nuclear translocation of STAT3 protein. Then, we noted that EVO arrested the cell cycle, caused apoptosis, and downregulated the expression of various carcinogenic markers such as B-cell lymphoma 2 (Bcl-2), B-cell lymphoma-extra large (Bcl-xL), cyclin D1, cyclooxygenase 2 (COX-2), survivin, vascular endothelial growth factor (VEGF), and matrix metallopeptidases 9 (MMP-9). Moreover, it was observed that in cPC-3 and DU145 cells transfected with c-Met small interfering RNA (siRNA), Src/STAT3 activation was also mitigated and led to a decrease in EVO-induced apoptotic cell death. According to our results, EVO can abrogate the activation of the c-Met/Src/STAT3 signaling axis and thus plays a role as a robust suppressor of tumor cell survival, proliferation, and angiogenesis.

The IκB Kinase Inhibitor ACHP Targets the STAT3 Signaling Pathway in Human Non-Small Cell Lung Carcinoma Cells

STAT3 is an oncogenic transcription factor that regulates the expression of genes which are involved in malignant transformation. Aberrant activation of STAT3 has been observed in a wide range of human malignancies and its role in negative prognosis is well-documented. In this report, we performed high-throughput virtual screening in search of STAT3 signaling inhibitors using a cheminformatics platform and identified 2-Amino-6-[2-(Cyclopropylmethoxy)-6-Hydroxyphenyl]-4-Piperidin-4-yl Nicotinonitrile (ACHP) as the inhibitor of the STAT3 signaling pathway. The predicted hit was evaluated in non-small cell lung cancer (NSCLC) cell lines for its STAT3 inhibitory activity. In vitro experiments suggested that ACHP decreased the cell viability and inhibited the phosphorylation of STAT3 on Tyr705 of NSCLC cells. In addition, ACHP imparted inhibitory activity on the constitutive activation of upstream protein tyrosine kinases, including JAK1, JAK2, and Src. ACHP decreased the nuclear translocation of STAT3 and downregulated its DNA binding ability. Apoptosis was evidenced by cleavage of caspase-3 and PARP with the subsequent decline in antiapoptotic proteins, including Bcl-2, Bcl-xl, and survivin. Overall, we report that ACHP can act as a potent STAT3 signaling inhibitor in NSCLC cell lines.