Guajadial reverses multidrug resistance by inhibiting ABC transporter expression and suppressing the PI3K/Akt pathway in drug-resistant breast cancer cells

Novel isoniazid-hydrazone derivatives induce cell growth inhibition, cell cycle arrest and apoptosis via mitochondria-dependent caspase activation and PI3K/AKT inhibition

In this study, seven isoniazid-hydrazone derivatives (3a-g) were synthesized and their structures elucidated by chromatographic techniques, and then the antiproliferative effects of these compounds on various cancer cells were tested. The advanced anticancer mechanism of the most potent compound was then investigated. Antiproliferative activities of the synthesized compounds were evaluated on human breast cancer MCF-7, lung cancer A-549, colon cancer HT-29, and non-cancerous mouse fibroblast 3T3-L1 cell lines by XTT assay. Flow cytometry analysis were carried out to determine cell cycle distribution, apoptosis, mitochondrial membrane potential, multi-caspase activity, and expression of PI3K/AKT signaling pathway. The XTT results showed that all the title molecules displayed cytotoxic activity at varying strengths in different dose ranges, and among them, the strongest cytotoxic effect and high selectivity were exerted by 3d against MCF-7 cells with the IC50 value of 11.35 µM and selectivity index of 8.65. Flow cytometry results revealed that compound 3d induced apoptosis through mitochondrial membrane disruption and multi-caspase activation in MCF-7 cells. It also inhibited the cell proliferation via inhibition of expression of PI3K/AKT and arrested the cell cycle at G0/G1 phase. In conclusion, all these data disclosed that among the synthesized compounds, 3d is notable for in vivo anticancer studies.

Oestrogen receptor positive breast cancer and its embedded mechanism: breast cancer resistance to conventional drugs and related therapies, a review

Traditional medication and alternative therapies have long been used to treat breast cancer. One of the main problems with current treatments is that there is an increase in drug resistance in the cancer cells owing to genetic differences such as mutational changes, epigenetic changes and miRNA (microRNA) alterations such as miR-1246, miR-298, miR-27b and miR-33a, along with epigenetic modifications, such as Histone3 acetylation and CCCTC-Binding Factor (CTCF) hypermethylation for drug resistance in breast cancer cell lines. Certain forms of conventional drug resistance have been linked to genetic changes in genes such as ABCB1, AKT, S100A8/A9, TAGLN2 and NPM. This review aims to explore the current approaches to counter breast cancer, the action mechanism, along with novel therapeutic methods endowing potential drug resistance. The investigation of novel therapeutic approaches sheds light on the phenomenon of drug resistance including genetic variations that impact distinct forms of oestrogen receptor (ER) cancer, genetic changes, epigenetics-reported resistance and their identification in patients. Long-term effective therapy for breast cancer includes selective oestrogen receptor modulators, selective oestrogen receptor degraders and genetic variations, such as mutations in nuclear genes, epigenetic modifications and miRNA alterations in target proteins. Novel research addressing combinational therapies including maytansine, photodynamic therapy, guajadiol, talazoparib, COX2 inhibitors and miRNA 1246 inhibitors have been developed to improve patient survival rates.

The determinants of metabolic discrepancies in aerobic glycolysis: Providing potential targets for breast cancer treatment

Altered aerobic glycolysis is the robust mechanism to support cancer cell survival and proliferation beyond the maintenance of cellular energy metabolism. Several investigators portrayed the important role of deregulated glycolysis in different cancers, including breast cancer. Breast cancer is the most ubiquitous form of cancer and the primary cause of cancer death in women worldwide. Breast cancer with increased glycolytic flux is hampered to eradicate with current therapies and can result in tumor recurrence. In spite of the low order efficiency of ATP production, cancer cells are highly addicted to glycolysis. The glycolytic dependency of cancer cells provides potential therapeutic strategies to preferentially kill cancer cells by inhibiting glycolysis using antiglycolytic agents. The present review emphasizes the most recent research on the implication of glycolytic enzymes, including glucose transporters (GLUTs), hexokinase (HK), phosphofructokinase (PFK), pyruvate kinase (PK), lactate dehydrogenase-A (LDHA), associated signalling pathways and transcription factors, as well as the antiglycolytic agents that target key glycolytic enzymes in breast cancer. The potential activity of glycolytic inhibitors impinges cancer prevalence and cellular resistance to conventional drugs even under worse physiological conditions such as hypoxia. As a single agent or in combination with other chemotherapeutic drugs, it provides the feasibility of new therapeutic modalities against a wide spectrum of human cancers.

Natural medicinal compounds target signal transduction pathways to overcome ABC drug efflux transporter-mediated multidrug resistance in cancer

ATP-binding cassette (ABC) transporters such as ABCB1, ABCG2, and ABCC1 are the major players in drug efflux-mediated multidrug resistance (MDR), which severely affects the efficacy of chemotherapy. Several synthetic compounds block the drug transport by ABC transporters; however, they exhibit a narrow therapeutic window, and produce side effects in non-target normal tissues. Conversely, the downregulation of the expression of ABC drug transporters seems to be a promising strategy to reverse MDR in cancer cells. Several signaling pathways, such as NF-κB, STAT3, Gli, NICD, YAP/TAZ, and Nrf2 upregulate the expression of ABC drug transporters in drug-resistant cancers. Recently, natural medicinal compounds have gained importance to overcome the ABC drug-efflux pump-mediated MDR in cancer. These compounds target transcription factors and the associated signal transduction pathways, thereby downregulating the expression of ABC transporters in drug-resistant cancer cells. Several potent natural compounds have been identified as lead candidates to synergistically enhance chemotherapeutic efficacy, and a few of them are already in clinical trials. Therefore, modulation of signal transduction pathways using natural medicinal compounds for the reversal of ABC drug transporter-mediated MDR in cancer is a novel approach for improving the efficiency of the existing chemotherapeutics. In this review, we discuss the modulatory role of natural medicinal compounds on cellular signaling pathways that regulate the expression of ABC transporters in drug-resistant cancer cells.

Addition of PI3K/AKT/mTOR inhibitors to fulvestrant for advanced HR+/HER2- breast cancer: a systematic review and meta-analysis

Purpose: To analyze whether adding PI3K/AKT/mTOR inhibitors to fulvestrant could restore endocrine therapy sensitivity for the treatment of postmenopausal patients with HR+, HER2- breast cancer. Methods: This meta-analysis was performed using RevMan 5.4 analysis software. Results: Nine studies that included a total of 3199 patients were analyzed. Compared with fulvestrant alone, the addition of PI3K/AKT/mTOR inhibitors significantly prolonged progression-free survival, overall survival and objective response rate of patients in both the total and PI3K-pathway-activated population. The number of grade 3-5 adverse events was also significantly higher. Conclusion: The addition of PI3K/AKT/mTOR to fulvestrant resulted in potential benefits; however, there may be a higher risk, which needs to be carefully managed.

ATP-binding cassette efflux transporters and MDR in cancer

Of the many known multidrug resistance (MDR) mechanisms, ATP-binding cassette (ABC) transporters expelling drug molecules out of cells is a major factor limiting the efficacy of present-day anticancer drugs. In this review, we highlights updated information on the structure, function, and regulatory mechanisms of major MDR-related ABC transporters, such as P-glycoprotein (P-gp), multidrug resistance protein 1 (MRP1), and breast cancer resistance protein (BCRP), and the effect of modulators on their functions. We also provide focused information on different modulators of ABC transporters that could be utilized against the emerging MDR crisis in cancer treatment. Finally, we discuss the importance of ABC transporters as therapeutic targets in light of future strategic planning for translating ABC transporter inhibitors into clinical practice.

Plumbagin Enhances the Anticancer Effects of PF Chemotherapy via Downregulation of the PI3K/AKT/mTOR/p70S6K Pathway in Human Tongue Squamous Cell Carcinoma

Cisplatin plus 5-fluorouracil (PF) is used as the standard neoadjuvant chemotherapy (also called preoperative chemotherapy) in the treatment of tongue squamous cell carcinoma (TSCC). Although PF chemotherapy reduces the distant metastasis of TSCC, the five-year survival rate has not significantly improved. In recent years, components considered in traditional Chinese medicine have been researched as adjuvant drugs for radiotherapy and chemotherapy. Plumbagin (PB) is a quinone component isolated from Plumbago zeylanica L. Notably, PB demonstrates numerous anticancer properties. In order to examine the chemosensitization effect of PB on PF and its associated mechanisms, in vitro experiments using TSCC Cal27 and cisplatin (CDDP)-resistant Cal27/CDDP cells were carried out in the present study, and the results were subsequently verified using nude mice xenografts. Results of the present study demonstrated that PB enhanced the anticancer effects of PF on the proliferation, migration, and invasion of Cal27 and Cal27/CDDP cells. Cell cycle assays demonstrated that both Cal27 and Cal27/CDDP cells were arrested in the S phase following the combined treatment of PF and PB. Moreover, the PF and PB combination group induced higher levels of apoptosis in Cal27 and Cal27/CDDP cells compared with the group treated with PF alone. In addition, the results of the present study demonstrated that combined PB and PF inhibited the PI3K/AKT/mTOR/p70S6K pathway in TSCC cells. Moreover, the weight and volumes of tumors in nude mice were reduced following treatment with a combination of PF and PB. Results of the present study also demonstrated that the expression levels of Ki67 were markedly reduced in the combined treatment group compared with the group treated with PF alone. In summary, the results of the present study demonstrated that PB enhanced the PF sensitivity of TSCC through induction of S-phase arrest and apoptosis via the PI3K/AKT/mTOR/p70S6K pathway.

Structure-Based Drug Design and Synthesis of Novel N-Aryl-2,4-bithiazole-2-amine CYP1B1-Selective Inhibitors in Overcoming Taxol Resistance in A549 Cells

As a promising therapeutic target for cancer, CYP1B1 is overexpressed in Taxol-resistant A549 cells; however, its role in drug resistance still remains unclear. Bioinformatic analysis data indicated that CYP1B1 was closely correlated with AKT/ERK1/2 and focal adhesion pathways, thereby playing an important role in Taxol resistance and cancer migration/invasion. Along similar lines, the AhR agonist 7,12-dimethylbenz[a]anthracene (DMBA) enhanced Taxol resistance and promoted migration/invasion of A549 and H460 cells likely stemming from CYP1B1 upregulation. Moreover, 83 novel N-aryl-2,4-bithiazole-2-amine CYP1B1-selective inhibitors were designed and synthesized to verify the role of CYP1B1 in Taxol-resistant A549 cells. Impressively, the most potent and selective one, namely, 77, remarkably inhibited AKT/ERK1/2 and FAK/SRC pathways and thereby reversed Taxol resistance as well as inhibited both migration and invasion of A549/Taxol cells. Collectively, this study not only displayed the role of CYP1B1 in Taxol resistance and cancer migration/invasion but also helped unlock the CYP1B1-oriented anticancer discovery.

Hydroxygenkwanin Improves the Efficacy of Cytotoxic Drugs in ABCG2-Overexpressing Multidrug-Resistant Cancer Cells

Hydroxygenkwanin, a flavonoid isolated from the leaves of the Daphne genkwa plant, is known to have pharmacological properties; however, its modulatory effect on multidrug resistance, which is (MDR) mediated by ATP-binding cassette (ABC) drug transporters, has not been investigated. In this study, we examine the interaction between hydroxygenkwanin, ABCB1, and ABCG2, which are two of the most well-characterized ABC transporters known to contribute to clinical MDR in cancer patients. Hydroxygenkwanin is not an efflux substrate of either ABCB1 or ABCG2. We discovered that, in a concentration-dependent manner, hydroxygenkwanin significantly reverses ABCG2-mediated resistance to multiple cytotoxic anticancer drugs in ABCG2-overexpressing multidrug-resistant cancer cells. Although it inhibited the drug transport function of ABCG2, it had no significant effect on the protein expression of this transporter in cancer cells. Experimental data showing that hydroxygenkwanin stimulates the ATPase activity of ABCG2, and in silico docking analysis of hydroxygenkwanin binding to the inward-open conformation of human ABCG2, further indicate that hydroxygenkwanin sensitizes ABCG2-overexpressing cancer cells by binding to the substrate-binding pocket of ABCG2 and attenuating the transport function of ABCG2. This study demonstrates the potential use of hydroxygenkwanin as an effective inhibitor of ABCG2 in drug combination therapy trials for patients with tumors expressing higher levels of ABCG2.

ABC transporters in breast cancer: their roles in multidrug resistance and beyond

ATP-binding cassette (ABC) transporters are membrane-spanning proteins involved in cholesterol homeostasis, transport of various molecules in and out of cells and organelles, oxidative stress, immune recognition, and drug efflux. They are long implicated in the development of multidrug resistance in cancer chemotherapy. Existing clinical and molecular evidence has also linked ABC transporters with cancer pathogenesis, prognostics, and therapy. In this review, we aim to provide a comprehensive update on all ABC transporters and their roles in drug resistance in breast cancer (BC). For solid tumours such as BC, various ABC transporters are highly expressed in less differentiated subtypes and metastases. ABCA1, ABCB1 and ABCG2 are key players in BC chemoresistance. Restraining these transporters has evolved as a possible mechanism to reverse this phenomenon. Further, ABCB1 and ABCC1 are important in BC prognosis. Newer therapeutic approaches have been developed to target all these molecules to dysregulate their effect, reduce cell viability, induce apoptosis, and increase drug sensitivity. In the future, targeted therapy for specific genetic variations and upstream or downstream molecules can help improve patient prognosis.

TSPAN1, a novel tetraspanin member highly involved in carcinogenesis and chemoresistance

The tetraspanin (TSPAN) family constitutes a poorly explored family of membrane receptors involved in various physiological processes, with relevant roles in anchoring multiple proteins, acting as scaffolding proteins, and cell signaling. Recent studies have increasingly demonstrated the involvement of TSPANs in cancer. In particular, tetraspanin 1 (also known as TSPAN1, NET-1, TM4C, C4.8 or GEF) has been implicated in cell survival, proliferation and invasion. Recently, our laboratory revealed a key role of TSPAN1 in the acquired resistance of tumor cells to conventional chemotherapy (e.g., cisplatin). In this review, we summarize and discuss the latest research on the physiological mechanisms of TSPANs in cancer and, in particular, on TSPAN1 regulating resistance to chemotherapy. A model of TSPAN1 action is proposed, and the potential of targeting TSPAN1 in anticancer therapeutic strategies is discussed.

Developing a Novel Indium(III) Agent Based on Liposomes to Overcome Cisplatin-Induced Resistance in Breast Cancer by Multitargeting the Tumor Microenvironment Components

To overcome the resistance of cancer cells to platinum-based drugs and effectively suppress tumor growth, we developed a novel indium (In) agent based on liposomes (Lips). Thus, we not only obtained an In(III) thiosemicarbazone agent (5b) with remarkable cytotoxicity by optimizing a series of In(III) thiosemicarbazone agents (1b-5b) but also successfully constructed a novel 5b-loaded Lip (5b-Lip) delivery system. Importantly, in vitro and in vivo results revealed that 5b/5b-Lip overcame the tumor cell resistance and effectively inhibited MCF-7/DDP tumor growth. In addition, Lips improved the intracellular accumulation of 5b. We also confirmed the mechanism by which 5b/5b-Lip overcomes breast cancer cell resistance. 5b/5b-Lip cannot act against DNA in cancer cells but attacks the two cell components in the tumor microenvironment, namely, by inducing apoptosis and lethal autophagy of cancer cells and resetting tumor-promoting M2 macrophages to the tumor-killing M1 phenotype.

RecQ-like helicase 4 (RECQL4) exacerbates resistance to oxaliplatin in colon adenocarcinoma via activation of the PI3K/AKT signaling pathway

Oxaliplatin (OXA) resistance is a great challenge for colon adenocarcinoma (COAD) chemotherapy. The promoting role of RecQ-Like Helicase 4 (RECQL4) in chemoresistance to platinum-based drugs has been identified, whereas the effect and specific mechanism of RECQL4 in regulating OXA resistance within COAD have not been explicated yet. In this work, RECQL4 mRNA expression was detected by RT-qPCR. RECQL4, phosphorylated PI3K (p-PI3K), PI3K, phosphorylated AKT (p-AKT), and AKT protein expression were measured by western blotting. CCK-8, flow cytometry, wound healing, and transwell assays were utilized to analyze OXA resistance, cell proliferation, apoptosis, cell cycle, migration and invasion. Herein, we found RECQL4 was upregulated in COAD, especially in OXA-resistant COAD tissues and cells. RECQL4 overexpression facilitated proliferation and metastasis of OXA-resistant COAD cells; on the contrary, RECQL4 knockdown attenuated proliferative and metastatic capabilities in OXA-resistant COAD cells. Moreover, RECQL4 promoted OXA resistance in OXA-resistant COAD cells via activating the P13 K/AKT signaling. To sum up, the results suggest that RECQL4 depletion may be a crucial mechanism to reverse OXA resistance in COAD via inhibition of the P13 K/AKT pathway in vitro, thereby providing a novel target for overcoming OXA resistance in COAD.

Clinically-Relevant ABC Transporter for Anti-Cancer Drug Resistance

Multiple drug resistance (MDR), referring to the resistance of cancer cells to a broad spectrum of structurally and mechanistically unrelated drugs across membranes, severely impairs the response to chemotherapy and leads to chemotherapy failure. Overexpression of ATP binding cassette (ABC) transporters is a major contributing factor resulting in MDR, which can recognize and mediate the efflux of diverse drugs from cancer cells, thereby decreasing intracellular drug concentration. Therefore, modulators of ABC transporter could be used in combination with standard chemotherapeutic anticancer drugs to augment the therapeutic efficacy. This review summarizes the recent advances of important cancer-related ABC transporters, focusing on their physiological functions, structures, and the development of new compounds as ABC transporter inhibitors.

A New Chalcone Derivative C49 Reverses Doxorubicin Resistance in MCF-7/DOX Cells by Inhibiting P-Glycoprotein Expression

Objective: C49 is a chalcone derivative. The aim of the current study is to illuminate the efficacy of C49 in reversing multidrug resistance (MDR) in MCF-7/DOX cells and its underlying molecular mechanism. Methods: The cytotoxic effects of C49 on MCF-7/DOX cells were evaluated by MTT assay using different concentration (0-250 μmol/L) of C49. Cell proliferation was evaluated by colony formation assay. Cell death was examined by morphological analysis using Hoechst 33,258 staining. Flow cytometry and immunofluorescence were utilized to evaluate the intracellular accumulation of doxorubicin (DOX) and cell apoptosis. The differentially expressed genns between MCF-7 and MCF-7/DOX cells were analyzed by GEO database. The expression of PI3K/Akt pathway proteins were assessed by Western blot The activities of C49 combined with DOX was evaluated via xenograft tumor model in female BALB/c nude mice. Results: C49 inhibited the growth of MCF-7 cells (IC50 = 59.82 ± 2.10 μmol/L) and MCF-7/DOX cells (IC50 = 65.69 ± 8.11 μmol/L) with dosage-dependent and enhanced the cellular accumulation of DOX in MCF-7/DOX cells. The combination of C49 and DOX inhibited cell proliferation and promoted cell apoptosis. MCF-7/DOX cells regained drug sensibility with the combination treatment through inhibiting the expression of P-gp, p-PI3K and p-Akt proteins. Meanwhile, C49 significantly increased the anticancer efficacy of DOX in vivo. Conclusion: C49 combined with DOX restored DOX sensitivity in MCF-7/DOX cells through inhibiting P-gp protein.

PI3K/AKT pathway as a key link modulates the multidrug resistance of cancers

Multidrug resistance (MDR) is the dominant challenge in the failure of chemotherapy in cancers. Phosphatidylinositol 3-kinase (PI3K) is a lipid kinase that spreads intracellular signal cascades and regulates a variety of cellular processes. PI3Ks are considered significant causes of chemoresistance in cancer therapy. Protein kinase B (AKT) is also a significant downstream effecter of PI3K signaling, and it modulates several pathways, including inhibition of apoptosis, stimulation of cell growth, and modulation of cellular metabolism. This review highlights the aberrant activation of PI3K/AKT as a key link that modulates MDR. We summarize the regulation of numerous major targets correlated with the PI3K/AKT pathway, which is further related to MDR, including the expression of apoptosis-related protein, ABC transport and glycogen synthase kinase-3 beta (GSK-3β), synergism with nuclear factor kappa beta (NF-κB) and mammalian target of rapamycin (mTOR), and the regulation of glycolysis.

Astragaloside IV enhances cisplatin chemosensitivity in hepatocellular carcinoma by suppressing MRP2

Decreased chemosensitivity among tumor cells is often an obstacle in cisplatin (Cis) chemotherapy. Overexpression of multidrug resistance-associated protein 2 (MRP2) is a key mechanism underlying decreased Cis chemosensitivity and resistance. Astragaloside IV (AS IV) is an important component derived from the well-known traditional Chinese herb Astragalus membranaceus. The aim of this study was to explore the role of AS IV in enhancing the antitumor effect of Cis by suppressing MRP2 expression in HepG2 cells and H22 tumor-bearing mice. After co-treatment of HepG2 cells with Cis and AS IV, we assessed the effects on cell proliferation and apoptosis. Tumor growth and apoptosis assessment were performed to assess chemosensitivity in H22 tumor-bearing mice. We used western blotting, immunofluorescence assays, and immunohistochemistry assays to detect MRP2 expression in HepG2 cells, H22 tumor tissues and mouse kidney tissues. AS IV enhanced Cis chemosensitivity by increasing tumor cell apoptosis and slowing tumor growth in vitro and in vivo. MRP2 overexpression in tumor cells was induced by Cis, which contributes to decreased chemosensitivity and Cis resistance. Co-administration of AS IV suppressed MRP2 expression in tumor tissues, which might be an important mechanism for enhancing Cis chemosensitivity in hepatocellular carcinoma. Moreover, AS IV alleviated Cis-induced kidney injury in mice without changing MRP2 expression. In total, AS IV enhanced the antitumor effect of Cis against hepatocellular carcinoma by suppressing MRP2 expression in tumor cells. The results provide a new insight into the combined use of a chemotherapy drug and natural ingredients to treat cancer.

Abnormal expression of ABCD3 is an independent prognostic factor for colorectal cancer

ATP binding cassette subfamily D member 3 (ABCD3) is a member of the superfamily of ATP-binding cassette (ABC) transporters, which serve crucial roles in the process of tumor cell resistance to chemotherapy. The present study investigated the diagnostic and prognostic capabilities of ABCD3 in colorectal cancer (CRC) by bioinformatics analysis. Gene expression data and corresponding clinical information of patients with CRC were collected from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. The results demonstrated that ABCD3 mRNA level was decreased in CRC tissues compared with normal tissues following Wilcoxon test analysis. Furthermore, ABCD3 protein expression was significantly higher in normal colon tissues compared with colon adenocarcinoma tissues according to the Human Protein Atlas. In addition, the area under the Receiver Operating Characteristic curve based on comparison between the tumor and normal groups derived from TCGA and GEO databases demonstrated that the use of ABCD3 mRNA level may be used for the diagnosis of CRC. ABCD3 expression was significantly associated with clinical stage, T stage, and lymph node status following Kruskal-Wallis test or Wilcoxon rank sum test, logistic regression and χ² test. Furthermore, the results from Kaplan-Meier survival analysis indicated that low ABCD3 mRNA expression had a poorer prognosis value compared with ABCD3 high expression in patients with CRC. In addition, results from univariate Cox regression analysis indicated that ABCD3 mRNA expression was associated with overall survival (OS), and results from multivariate Cox analysis indicated that ABCD3 mRNA expression may be considered an independent prognostic factor from other clinical factors, such as clinical stage, sex and age. The results from Gene Set Enrichment Analysis demonstrated that the ABCD3 high-expression phenotype was differentially enriched in five biological processes, including apoptosis, cell cycle, renal cell carcinoma, thyroid cancer and colorectal cancer. The findings from this study demonstrated that ABCD3 mRNA expression may be considered as a potential diagnostic and prognostic biomarker in patients with CRC. ABCD3 expression levels may participate in the regulation of cell apoptosis and cell cycle. In addition, GSEA analysis identified Kyoto Encyclopaedia of Genes and Genomes pathways for renal cell carcinoma, thyroid cancer and CRC involving ABCD3.

Targets and mechanisms of sulforaphane derivatives obtained from cruciferous plants with special focus on breast cancer - contradictory effects and future perspectives

Breast cancer is the most common type of cancer among women. Therefore, discovery of new and effective drugs with fewer side effects is necessary to treat it. Sulforaphane (SFN) is an organosulfur compound obtained from cruciferous plants, such as broccoli and mustard, and it has the potential to treat breast cancer. Hence, it is vital to find out how SFN targets certain genes and cellular pathways in treating breast cancer. In this review, molecular targets and cellular pathways of SFN are described. Studies have shown SFN inhibits cell proliferation, causes apoptosis, stops cell cycle and has anti-oxidant activities. Increasing reactive oxygen species (ROS) produces oxidative stress, activates inflammatory transcription factors, and these result in inflammation leading to cancer. Increasing anti-oxidant potential of cells and discovering new targets to reduce ROS creation reduces oxidative stress and it eventually reduces cancer risks. In short, SFN effectively affects histone deacetylases involved in chromatin remodeling, gene expression, and Nrf2 anti-oxidant signaling. This review points to the potential of SFN to treat breast cancer as well as the importance of other new cruciferous compounds, derived from and isolated from mustard, to target Keap1 and Akt, two key regulators of cellular homeostasis.

Olean-28,13b-olide 2 plays a role in cisplatin-mediated apoptosis and reverses cisplatin resistance in human lung cancer through multiple signaling pathways

Lung cancer, similar to other chronic diseases, occurs due to perturbations in multiple signaling pathways. Mono-targeted therapies are not ideal since they are not likely to be effective for the treatment and prevention of lung cancer, and are often associated with drug resistance. Therefore, the development of multi-targeted agents is required for novel lung cancer therapies. Thioredoxin reductase (TrxR or TXNRD1) is a pivotal component of the thioredoxin (Trx) system. Various types of tumor cells are able to overexpress TrxR/Trx proteins in order to maintain tumor survival, and this overexpression has been shown to be associated with clinical outcomes, including irradiation and drug resistance. Emerging evidence has indicated that oleanolic acid (OA) and its derivatives exhibit potent anticancer activity, and are able to overcome drug resistance in cancer cell lines. In the present study, it was demonstrated that a novel synthesized OA family compound, olean-28,13b-olide 2 (OLO-2), synergistically enhanced cisplatin (CDDP)-mediated apoptosis, led to the activation of caspase-3 and the generation of reactive oxygen species (ROS), induced DNA damage, and inhibited the activation of the extracellular-signal-regulated kinase (ERK), signal transducer and activator of transcription 3 (STAT3), AKT and nuclear factor-κB (NF-κB) pathways in human multidrug-resistant A549/CDDP lung adenocarcinoma cells. Subsequent analyses revealed that OLO-2 inhibited P-glycoprotein (P-gp or ABCB1) and TrxR by reducing their expression at the protein and mRNA levels, and by suppressing P-gp ATPase and TrxR activities. Further biological evaluation indicated that OLO-2 significantly reduced Trx and excision repair cross-complementary1 (ERCC1) protein expression and significantly inhibited the proliferation of drug-sensitive (A549) and multidrug-resistant (A549/CDDP) non-small cell lung cancer (NSCLC) cells, but had no effect on non-tumor lung epithelial-like cells. In addition, the present study demonstrated, for the first time, to the best of our knowledge, that overexpressing or knocking down TrxR in NSCLC cells enhanced or attenuated, respectively, the resistance of NSCLC cells against CDDP, which indicated that TrxR plays an important role in CDDP resistance and functions as a protector of NSCLC against chemotherapeutic drugs. OLO-2 treatment also exhibited up to 4.6-fold selectivity against human lung adenocarcinoma cells. Taken together, the results of the present study shed light on the drug resistance-reversing effects of OLO-2 in lung cancer cells.