Sulforaphane inhibits proliferation and invasive activity of everolimus-resistant kidney cancer cells in vitro

The role of natural products versus miRNA in renal cell carcinoma: implications for disease mechanisms and diagnostic markers

Natural products are chemical compounds produced by living organisms. They are isolated and purified to determine their function and can potentially be used as therapeutic agents. The ability of some bioactive natural products to modify the course of cancer is fascinating and promising. In the past 50 years, there have been advancements in cancer therapy that have increased survival rates for localized tumors. However, there has been little progress in treating advanced renal cell carcinoma (RCC), which is resistant to radiation and chemotherapy. Oncogenes and tumor suppressors are two roles played by microRNAs (miRNAs). They are involved in important pathogenetic mechanisms like hypoxia and epithelial-mesenchymal transition (EMT); they control apoptosis, cell growth, migration, invasion, angiogenesis, and proliferation through target proteins involved in various signaling pathways. Depending on their expression pattern, miRNAs may identify certain subtypes of RCC or distinguish tumor tissue from healthy renal tissue. As diagnostic biomarkers of RCC, circulating miRNAs show promise. There is a correlation between the expression patterns of several miRNAs and the prognosis and diagnosis of patients with RCC. Potentially high-risk primary tumors may be identified by comparing original tumor tissue with metastases. Variations in miRNA expression between treatment-sensitive and therapy-resistant patients' tissues and serum allow for the estimation of responsiveness to target therapy. Our knowledge of miRNAs' function in RCC etiology has a tremendous uptick. Finding and validating their gene targets could have an immediate effect on creating anticancer treatments based on miRNAs. Several miRNAs have the potential to be used as biomarkers for diagnosis and prognosis. This review provides an in-depth analysis of the current knowledge regarding natural compounds and their modes of action in combating cancer. Also, this study aims to give information about the diagnostic and prognostic value of miRNAs as cancer biomarkers and their involvement in the pathogenesis of RCC.

Natural Compounds Derived from Plants on Prevention and Treatment of Renal Cell Carcinoma: A Literature Review

Renal cell carcinoma (RCC) accounts for roughly 85% of all malignant kidney cancer. Therapeutic options for RCC have expanded rapidly over the past decade. Targeted therapy and immunotherapy have ushered in a new era of the treatment of RCC, which has facilitated the outcomes of RCC. However, the related adverse effects and drug resistance remain an urgent issue. Natural compounds are optional strategies to reduce mobility. Natural compounds are favored by clinicians and researchers due to their good tolerance and low economic burden. Many studies have explored the anti-RCC activity of natural products and revealed relevant mechanisms. In this article, the chemoprevention and therapeutic potential of natural compounds is reviewed and the mechanisms regarding natural compounds are explored.

Plant-Derived Sulforaphane Suppresses Growth and Proliferation of Drug-Sensitive and Drug-Resistant Bladder Cancer Cell Lines In Vitro

Simple Summary

The natural compound sulforaphane is highly popular among tumor patients, since it is suggested to prevent oncogenesis and cancer progression. However, knowledge about its precise mode of action, particularly when drug resistance has been established, remains poor. The present study demonstrates the proliferation-blocking effects of SFN on a panel of drug-resistant bladder cancer cell lines.

Abstract

Combined cisplatin–gemcitabine (GC) application is standard for treating muscle-invasive bladder cancer. However, since rapid resistance to treatment often develops, many patients turn to supplements in the form of plant-based compounds. Sulforaphane (SFN), derived from cruciferous vegetables, is one such compound, and the present study was designed to investigate its influence on growth and proliferation in a panel of drug-sensitive bladder cancer cell lines, as well as their gemcitabine- and cisplatin-resistant counterparts. Chemo-sensitive and -resistant RT4, RT112, T24, and TCCSUP cell lines were exposed to SFN in different concentrations, and tumor growth, proliferation, and clone formation were evaluated, in addition to apoptosis and cell cycle progression. Means of action were investigated by assaying cell-cycle-regulating proteins and the mechanistic target of rapamycin (mTOR)/AKT signaling cascade. SFN significantly inhibited growth, proliferation, and clone formation in all four tumor cell lines. Cells were arrested in the G2/M and/or S phase, and alteration of the CDK–cyclin axis was closely associated with cell growth inhibition. The AKT/mTOR signaling pathway was deactivated in three of the cell lines. Acetylation of histone H3 was up-regulated. SFN, therefore, does exert tumor-suppressive properties in cisplatin- and gemcitabine-resistant bladder cancer cells and could be beneficial in optimizing bladder cancer therapy.

Phytochemicals for the Prevention and Treatment of Renal Cell Carcinoma: Preclinical and Clinical Evidence and Molecular Mechanisms

Simple Summary

Renal cell carcinoma (RCC) is the most frequently diagnosed kidney cancer. Once RCC metastasizes, successful treatment is difficult to achieve. There is an apparent need for novel approaches to prevent and treat RCC. Phytochemicals are naturally derived compounds gaining increasing scientific interest due to their cancer preventive and chemotherapeutic properties. These phytochemicals have been shown to exhibit a multitude of anticancer effects against RCC. In this systematic review, we critically evaluate the potential these natural compounds possess for the prevention and treatment of RCC and discuss the future implications this may have in the fight against kidney cancer.

Abstract

Renal cell carcinoma (RCC) is associated with about 90% of renal malignancies, and its incidence is increasing globally. Plant-derived compounds have gained significant attention in the scientific community for their preventative and therapeutic effects on cancer. To evaluate the anticancer potential of phytocompounds for RCC, we compiled a comprehensive and systematic review of the available literature. Our work was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria. The literature search was performed using scholarly databases such as PubMed, Scopus, and ScienceDirect and keywords such as renal cell carcinoma, phytochemicals, cancer, tumor, proliferation, apoptosis, prevention, treatment, in vitro, in vivo, and clinical studies. Based on in vitro results, various phytochemicals, such as phenolics, terpenoids, alkaloids, and sulfur-containing compounds, suppressed cell viability, proliferation and growth, showed cytotoxic activity, inhibited invasion and migration, and enhanced the efficacy of chemotherapeutic drugs in RCC. In various animal tumor models, phytochemicals suppressed renal tumor growth, reduced tumor size, and hindered angiogenesis and metastasis. The relevant antineoplastic mechanisms involved upregulation of caspases, reduction in cyclin activity, induction of cell cycle arrest and apoptosis via modulation of a plethora of cell signaling pathways. Clinical studies demonstrated a reduced risk for the development of kidney cancer and enhancement of the efficacy of chemotherapeutic drugs. Both preclinical and clinical studies displayed significant promise of utilizing phytochemicals for the prevention and treatment of RCC. Further research, confirming the mechanisms and regulatory pathways, along with randomized controlled trials, are needed to establish the use of phytochemicals in clinical practice.

Shikonin Inhibits Cell Growth of Sunitinib-Resistant Renal Cell Carcinoma by Activating the Necrosome Complex and Inhibiting the AKT/mTOR Signaling Pathway

Therapy resistance remains a major challenge in treating advanced renal cell carcinoma (RCC), making more effective treatment strategies crucial. Shikonin (SHI) from traditional Chinese medicine has exhibited antitumor properties in several tumor entities. We, therefore, currently investigated SHI's impact on progressive growth and metastatic behavior in therapy-sensitive (parental) and therapy-resistant Caki-1, 786-O, KTCTL-26, and A498 RCC cells. Tumor cell growth, proliferation, clonogenic capacity, cell cycle phase distribution, induction of cell death (apoptosis and necroptosis), and the expression and activity of regulating and signaling proteins were evaluated. Moreover, the adhesion and chemotactic activity of the RCC cells after exposure to SHI were investigated. SHI significantly inhibited the growth, proliferation, and clone formation in parental and sunitinib-resistant RCC cells by G2/M phase arrest through down-regulation of cell cycle activating proteins. Furthermore, SHI induced apoptosis and necroptosis by activating necrosome complex proteins. Concomitantly, SHI impaired the AKT/mTOR pathway. Adhesion and motility were cell line specifically affected by SHI. Thus, SHI may hold promise as an additive option in treating patients with advanced and therapy-resistant RCC.

Artesunate Inhibits Growth of Sunitinib-Resistant Renal Cell Carcinoma Cells through Cell Cycle Arrest and Induction of Ferroptosis

Simple Summary

Renal cell carcinoma (RCC) is the most common kidney malignancy. Due to development of therapy resistance, efficacy of conventional drugs such as sunitinib is limited. Artesunate (ART), a drug originating from Traditional Chinese Medicine, has exhibited anti-tumor effects in several non-urologic tumors. ART inhibited growth, reduced metastatic properties, and curtailed metabolism in sunitinib-sensitive and sunitinib–resistant RCC cells. In three of four tested cell lines, ART’s growth inhibitory effects were accompanied by cell cycle arrest and modulation of cell cycle regulating proteins. In a fourth cell line, KTCTL-26, ART evoked ferroptosis, an iron-dependent cell death, and exhibited stronger anti-tumor effects than in the other cell lines. The regulatory protein, p53, was only detectable in the KTCTL-26 cells, possibly making p53 a predictive marker of cancer that may respond better to ART. ART, therefore, may hold promise as an additive therapy option for selected patients with advanced or therapy-resistant RCC.

Abstract

Although innovative therapeutic concepts have led to better treatment of advanced renal cell carcinoma (RCC), efficacy is still limited due to the tumor developing resistance to applied drugs. Artesunate (ART) has demonstrated anti-tumor effects in different tumor entities. This study was designed to investigate the impact of ART (1–100 µM) on the sunitinib-resistant RCC cell lines, Caki-1, 786-O, KTCTL26, and A-498. Therapy-sensitive (parental) and untreated cells served as controls. ART’s impact on tumor cell growth, proliferation, clonogenic growth, apoptosis, necrosis, ferroptosis, and metabolic activity was evaluated. Cell cycle distribution, the expression of cell cycle regulating proteins, p53, and the occurrence of reactive oxygen species (ROS) were investigated. ART significantly increased cytotoxicity and inhibited proliferation and clonogenic growth in both parental and sunitinib-resistant RCC cells. In Caki-1, 786-O, and A-498 cell lines growth inhibition was associated with G0/G1 phase arrest and distinct modulation of cell cycle regulating proteins. KTCTL-26 cells were mainly affected by ART through ROS generation, ferroptosis, and decreased metabolism. p53 exclusively appeared in the KTCTL-26 cells, indicating that p53 might be predictive for ART-dependent ferroptosis. Thus, ART may hold promise for treating selected patients with advanced and even therapy-resistant RCC.

Research progress of mTOR inhibitors

Mammalian target of rapamycin (mTOR) is a highly conserved Serine/Threonine (Ser/Thr) protein kinase, which belongs to phosphatidylinositol-3-kinase-related kinase (PIKK) protein family. mTOR exists as two types of protein complex: mTORC1 and mTORC2, which act as central controller regulating processes of cell metabolism, growth, proliferation, survival and autophagy. The mTOR inhibitors block mTOR signaling pathway, producing anti-inflammatory, anti-proliferative, autophagy and apoptosis induction effects, thus mTOR inhibitors are mainly used in cancer therapy. At present, mTOR inhibitors are divided into four categories: Antibiotic allosteric mTOR inhibitors (first generation), ATP-competitive mTOR inhibitors (second generation), mTOR/PI3K dual inhibitors (second generation) and other new mTOR inhibitors (third generation). In this article, these four categories of mTOR inhibitors and their structures, properties and some clinical researches will be introduced. Among them, we focus on the structure of mTOR inhibitors and try to analyze the structure-activity relationship. mTOR inhibitors are classified according to their chemical structure and their contents are introduced systematically. Moreover, some natural products that have direct or indirect mTOR inhibitory activities are introduced together. In this article, we analyzed the target, binding mode and structure-activity relationship of each generation of mTOR inhibitors and proposed two hypothetic scaffolds (the inverted-Y-shape scaffold and the C-shape scaffold) for the second generation of mTOR inhibitors. These findings may provide some help or reference for drug designing, drug modification or the future development of mTOR inhibitor.

Chronic Sulforaphane Administration Inhibits Resistance to the mTOR-Inhibitor Everolimus in Bladder Cancer Cells

Progressive bladder cancer growth is associated with abnormal activation of the mammalian target of the rapamycin (mTOR) pathway, but treatment with an mTOR inhibitor has not been as effective as expected. Rather, resistance develops under chronic drug use, prompting many patients to lower their relapse risk by turning to natural, plant-derived products. The present study was designed to evaluate whether the natural compound, sulforaphane (SFN), combined with the mTOR inhibitor everolimus, could block the growth and proliferation of bladder cancer cells in the short- and long-term. The bladder cancer cell lines RT112, UMUC3, and TCCSUP were exposed short- (24 h) or long-term (8 weeks) to everolimus (0.5 nM) or SFN (2.5 µM) alone or in combination. Cell growth, proliferation, apoptosis, cell cycle progression, and cell cycle regulating proteins were evaluated. siRNA blockade was used to investigate the functional impact of the proteins. Short-term application of SFN and/or everolimus resulted in significant tumor growth suppression, with additive inhibition on clonogenic tumor growth. Long-term everolimus treatment resulted in resistance development characterized by continued growth, and was associated with elevated Akt-mTOR signaling and cyclin-dependent kinase (CDK)1 phosphorylation and down-regulation of p19 and p27. In contrast, SFN alone or SFN+everolimus reduced cell growth and proliferation. Akt and Rictor signaling remained low, and p19 and p27 expressions were high under combined drug treatment. Long-term exposure to SFN+everolimus also induced acetylation of the H3 and H4 histones. Phosphorylation of CDK1 was diminished, whereby down-regulation of CDK1 and its binding partner, Cyclin B, inhibited tumor growth. In conclusion, the addition of SFN to the long-term everolimus application inhibits resistance development in bladder cancer cells in vitro. Therefore, sulforaphane may hold potential for treating bladder carcinoma in patients with resistance to an mTOR inhibitor.

Tumor hypoxia directed multimodal nanotherapy for overcoming drug resistance in renal cell carcinoma and reprogramming macrophages

Drug resistance is one of the significant clinical burden in renal cell carcinoma (RCC). The development of drug resistance is attributed to many factors, including impairment of apoptosis, elevation of carbonic anhydrase IX (CA IX, a marker of tumor hypoxia), and infiltration of tumorigenic immune cells. To alleviate the drug resistance, we have used Sorafenib (Sor) in combination with tumor hypoxia directed nanoparticle (NP) loaded with a new class of apoptosis inducer, CFM 4.16 (C4.16), namely CA IX-C4.16. The NP is designed to selectively deliver the payload to the hypoxic tumor (core), provoke superior cell death in parental (WT) and Everolimus-resistant (Evr-res) RCC and selectively downmodulate tumorigenic M2-macrophage. Copper-free 'click' chemistry was utilized for conjugating SMA-TPGS with Acetazolamide (ATZ, a CA IX-specific targeting ligand). The NP was further tagged with a clinically approved NIR dye (S0456) for evaluating hypoxic tumor core penetration and organ distribution. Imaging of tumor spheroid treated with NIR dye-labeled CA IX-SMA-TPGS revealed remarkable tumor core penetration that was modulated by CA IX-mediated targeting in hypoxic-A498 RCC cells. The significant cell killing effect with synergistic combination index (CI) of CA IX-C4.16 and Sor treatment suggests efficient reversal of Evr-resistance in A498 cells. The CA IX directed nanoplatform in combination with Sor has shown multiple benefits in overcoming drug resistance through (i) inhibition of p-AKT, (ii) upregulation of tumoricidal M1 macrophages resulting in induction of caspase 3/7 mediated apoptosis of Evr-res A498 cells in macrophage-RCC co-culturing condition, (iii) significant in vitro and in vivo Evr-res A498 tumor growth inhibition as compared to individual therapy, and (iv) untraceable liver and kidney toxicity in mice. Near-infrared (NIR) imaging of CA IX-SMA-TPGS-S0456 in Evr-res A498 RCC model exhibited significant accumulation of CA IX-oligomer in tumor core with >3-fold higher tumor uptake as compared to control. In conclusion, this proof-of-concept study demonstrates versatile tumor hypoxia directed nanoplatform that can work in synergy with existing drugs for reversing drug-resistance in RCC accompanied with re-education of tumor-associated macrophages, that could be applied universally for several hypoxic tumors.

Sulforaphane inhibits growth and blocks Wnt/β-catenin signaling of colorectal cancer cells

The naturally occurring isothiocyanate sulforaphane (SFN) from cruciferous vegetables is associated with growth inhibition of various cancer types, including colorectal cancer. Colorectal cancer is most frequently driven by hyperactive Wnt/β-catenin signaling. Here, we show that SFN treatment reduced growth of three unrelated colorectal cancer cell lines (SW480, DLD1 and HCT116) via induction of cell death and inhibition of proliferation. Importantly, SFN inhibits Wnt/β-catenin signaling in colorectal cancer cells as shown by inhibition of β-catenin-dependent luciferase reporters and repression of β-catenin target genes (AXIN2, LGR5). SFN inhibits Wnt signaling downstream of β-catenin degradation and induces the formation of nuclear β-catenin structures associated with closed chromatin. Co-expression of the transcription factors LEF1 or TCF4 prevented formation of these structures and rescued inhibition of Wnt/β-catenin signaling by SFN. Our findings provide a molecular basis explaining SFN effects in colorectal cancer cells and underline its potential for prevention and therapy of colorectal cancer.

SMYD3-associated pathway is involved in the anti-tumor effects of sulforaphane on gastric carcinoma cells

Sulforaphane (SFN), a natural compound derived from cruciferous vegetables, has been proved to possess potent anti-cancer activity. SMYD3 is a histone methyltransferase which is closely related to the proliferation and migration of cancer cells. This study showed that SFN could dose-dependently induce cell cycle arrest, stimulate apoptosis, and inhibit proliferation and migration of gastric carcinoma cells. Accompanied with these anti-cancer effects, SMYD3 and its downstream genes, myosin regulatory light chain 9, and cysteine-rich angiogenic inducer 61, was downregulated by SFN. Furthermore, overexpression of SMYD3 via transfection could abolish the effects of SFN, suggesting that SMYD3 might be an important mediator of SFN. To the best of our knowledge, this is the first report describing the role of SMYD3 in the anti-cancer of SFN. These findings might throw light on the development of novel anti-cancer drugs and functional food using SFN-rich cruciferous vegetables.

Sulforaphane protects granulosa cells against oxidative stress via activation of NRF2-ARE pathway

Sulforaphane (SFN) has been considered as an indirect antioxidant and potential inducer of the Nrf2-ARE pathway. This study was conducted to investigate the protective role of SFN against oxidative stress in bovine granulosa cells (GCs). GCs were collected from antral follicles (4-8 mm) and cultured according to the experimental design where group 1 = control, group 2 = treated with SFN, group 3 = treated with hydrogen peroxide (H₂O₂), group 4 = pretreated with SFN and then with H₂O₂ (protective) and group 5 = treated with H₂O₂ followed by SFN treatment (rescuing). Results showed that SFN pretreatment significantly increases cell viability and reduces cytotoxicity in GCs under oxidative stress. Following H₂O₂ exposure, expression of NRF2 was found to be significantly increased (p < 0.05) in SFN-pretreated cells, while no significant differences were observed between group 3 and group 5, although the expression was significantly increased compared to the control group. Moreover, the relative abundance of the NRF2 downstream target antioxidant genes (CAT, PRDX1, SOD1 and TXN1) were higher (fold change ranged from 7 to 14, p < 0.05) in sulforaphane pretreated GCs. Low level of ROS and lipid accumulation and higher mitochondrial activity were observed in GCs pretreated with SFN, whereas no such changes were observed in GCs treated with SFN after exposure to oxidative stress (group 5). Thus, we suggest that SFN pretreatment effectively protects GCs against oxidative damage through the activation of the NRF2-ARE pathway, whereas addition of SFN during oxidative insult failed to rescue GCs.

Relevance of the natural HDAC inhibitor sulforaphane as a chemopreventive agent in urologic tumors

Due to an increased understanding of molecular biology and the genomics of cancer, new and potent agents have been approved by the Food and Drug Administration (FDA) to fight this disease. However, all of these drugs cause severe side effects and resistance inevitably develops, re-activating tumor growth and dissemination. For this reason, patients turn to natural compounds as alternative or complementary treatment options, since it has been found that natural plant products may block, inhibit, or reverse cancer development. The present review focusses on the role of the natural compound sulforaphane (SFN) as an anti-tumor agent in urologic cancer. SFN is a natural compound found in cruciferous vegetables from the Brassicaceae family such as broccoli, cauliflower and cabbage. Several epidemiologic and clinical studies have documented chemopreventive properties of SFN, making it an interesting candidate for additive cancer treatment. SFN shows remarkable anti-tumor effects in vitro and in vivo without exerting toxicity. The review summarizes the current understanding of SFN and provides insights into its molecular mode of action with particular emphasis on epigenetic tumor control.

Anticancer Activity of Sulforaphane: The Epigenetic Mechanisms and the Nrf2 Signaling Pathway

Sulforaphane (SFN), a compound derived from cruciferous vegetables that has been shown to be safe and nontoxic, with minimal/no side effects, has been extensively studied due to its numerous bioactivities, such as anticancer and antioxidant activities. SFN exerts its anticancer effects by modulating key signaling pathways and genes involved in the induction of apoptosis, cell cycle arrest, and inhibition of angiogenesis. SFN also upregulates a series of cytoprotective genes by activating nuclear factor erythroid-2- (NF-E2-) related factor 2 (Nrf2), a critical transcription factor activated in response to oxidative stress; Nrf2 activation is also involved in the cancer-preventive effects of SFN. Accumulating evidence supports that epigenetic modification is an important factor in carcinogenesis and cancer progression, as epigenetic alterations often contribute to the inhibition of tumor-suppressor genes and the activation of oncogenes, which enables cells to acquire cancer-promoting properties. Studies on the mechanisms underlying the anticancer effects of SFN have shown that SFN can reverse such epigenetic alterations in cancers by targeting DNA methyltransferases (DNMTs), histone deacetyltransferases (HDACs), and noncoding RNAs. Therefore, in this review, we will discuss the anticancer activities of SFN and its mechanisms, with a particular emphasis on epigenetic modifications, including epigenetic reactivation of Nrf2.

Prognostic Value of RNASEH2A-, CDK1-, and CD151-Related Pathway Gene Profiling for Kidney Cancers

The nucleotide degrading enzyme gene RNASEH2A (ribonuclease H2 subunit A) has been found to be overexpressed in cancers. Our aim was to understand the role of RNASEH2A in cancer prognostication and to establish a scoring system based on the expressions of genes interacting with RNASEH2A. We screened the nucleotide degrading enzyme gene expression in RNAseq data of 14 cancer types derived from The Cancer Genome Atlas (TCGA) and found that RNASEH2A overexpression was associated with poor patient survival only in renal cell carcinomas (RCCs). Further cluster analyses of samples with poor outcomes revealed that cluster of differentiation 151 (CD151) upregulation correlated with low cyclin dependent kinase 1 (CDK1) and high RNASEH2A expression. The combination of low CD151 expression and high RNASEH2A expression resulted in impaired proliferation in four kidney cancer cell lines, suggesting potential synthetic dosage lethality (SDL) interactions between the two genes. A prognostication scoring system was established based on the expression levels of RNASEH2A-, CDK1-, and CD151-related genes, which could effectively predict the overall survival in a TCGA clear cell RCC cohort (n = 533, 995.3 versus 2242.2 days, p < 0.0001), in another clear cell renal cell carcinoma (ccRCC) cohort E-GEOD-22541 (n = 44, 390.0 versus 1889.2 days, p = 0.0007), and in a TCGA papillary RCC (pRCC) cohort (n = 287, 741.6 versus 1623.7 days, p < 0.0001). Our results provide a clinically applicable prognostication scoring system for renal cancers.

Sulforaphane for the chemoprevention of bladder cancer: molecular mechanism targeted approach

The clinical course for both early and late stage Bladder Cancer (BC) continues to be characterized by significant patient burden due to numerous occurrences and recurrences requiring frequent surveillance strategies, intravesical drug therapies, and even more aggressive treatments in patients with locally advanced or metastatic disease. For these reasons, BC is also the most expensive cancer to treat. Fortunately, BC offers an excellent platform for chemoprevention interventions with potential to optimize the systemic and local exposure of promising agents to the bladder mucosa. However, other than smoking cessation, there is a paucity of research that systematically examines agents for chemoprevention of bladder cancers. Adopting a systematic, molecular-mechanism based approach, the goal of this review is to summarize epidemiological, in vitro, and preclinical studies, including data regarding the safety, bioavailability, and efficacy of agents evaluated for bladder cancer chemoprevention. Based on the available studies, phytochemicals, specifically isothiocyanates such as sulforaphane, present in Brassicaceae or “cruciferous” vegetables in the precursor form of glucoraphanin are: (a) available in standardized formulations; (b) bioavailable- both systemically and in the bladder; (c) observed to be potent inhibitors of BC carcinogenesis through multiple mechanisms; and (d) without toxicities at these doses. Based on available evidence from epidemiological, in vitro, preclinical, and early phase trials, phytochemicals, specifically isothiocyanates (ITCs) such as sulforaphane (SFN) represent a promising potential chemopreventitive agent in bladder cancer.

RAPTOR up-regulation contributes to resistance of renal cancer cells to PI3K-mTOR inhibition

The outlook for patients with advanced renal cell cancer (RCC) has been improved by targeted agents including inhibitors of the PI3 kinase (PI3K)-AKT-mTOR axis, although treatment resistance is a major problem. Here, we aimed to understand how RCC cells acquire resistance to PI3K-mTOR inhibition. We used the RCC4 cell line to generate a model of in vitro resistance by continuous culture in PI3K-mTOR kinase inhibitor NVP-BEZ235 (BEZ235, Dactolisib). Resistant cells were cross-resistant to mTOR inhibitor AZD2014. Sensitivity was regained after 4 months drug withdrawal, and resistance was partially suppressed by HDAC inhibition, supporting an epigenetic mechanism. BEZ235-resistant cells up-regulated and/or activated numerous proteins including MET, ABL, Notch, IGF-1R, INSR and MEK/ERK. However, resistance was not reversed by inhibiting or depleting these pathways, suggesting that many induced changes were passengers not drivers of resistance. BEZ235 blocked phosphorylation of mTOR targets S6 and 4E-BP1 in parental cells, but 4E-BP1 remained phosphorylated in resistant cells, suggesting BEZ235-refractory mTORC1 activity. Consistent with this, resistant cells over-expressed mTORC1 component RAPTOR at the mRNA and protein level. Furthermore, BEZ235 resistance was suppressed by RAPTOR depletion, or allosteric mTORC1 inhibitor rapamycin. These data reveal that RAPTOR up-regulation contributes to PI3K-mTOR inhibitor resistance, and suggest that RAPTOR expression should be included in the pharmacodynamic assessment of mTOR kinase inhibitor trials.

The Role of Compounds Derived from Natural Supplement as Anticancer Agents in Renal Cell Carcinoma: A Review

Renal Cell Carcinoma (RCC) is the most prominent kidney cancer derived from renal tubules and accounts for roughly 85% of all malignant kidney cancer. Every year, over 60,000 new cases are registered, and about 14,000 people die from RCC. The incidence of this has been increasing significantly in the U.S. and other countries. An increased understanding of molecular biology and the genomics of RCC has uncovered several signaling pathways involved in the progression of this cancer. Significant advances in the treatment of RCC have been reported from agents approved by the Food and Drug Administration (FDA) that target these pathways. These agents have become drugs of choice because they demonstrate clinical benefit and increased survival in patients with metastatic disease. However, the patients eventually relapse and develop resistance to these drugs. To improve outcomes and seek approaches for producing long-term durable remission, the search for more effective therapies and preventative strategies are warranted. Treatment of RCC using natural products is one of these strategies to reduce the incidence. However, recent studies have focused on these chemoprevention agents as anti-cancer therapies given they can inhibit tumor cell grow and lack the severe side effects common to synthetic compounds. This review elaborates on the current understanding of natural products and their mechanisms of action as anti-cancer agents. The present review will provide information for possible use of these products alone or in combination with chemotherapy for the prevention and treatment of RCC.

Sulforaphane and myricetin act synergistically to induce apoptosis in 3T3‑L1 adipocytes

The aim of the present study was to investigate whether sulforaphane (SFN) and myricetin (Myr) synergistically induce apoptosis in adipocytes. The viability of mature 3T3-L1 adipocytes treated with 40 µM SFN and/or 100 µM Myr was assessed using an MTT assay. Apoptosis was assessed by Hoechst 33258 nuclear staining, and by detection of single-stranded DNA using an enzyme-linked immunosorbent assay. Compared with the effects of each compound alone, the combination of SFN and Myr synergistically reduced cell viability, induced apoptosis, increased pro-apoptotic Bcl-2 associated X protein expression, decreased anti-apoptotic B-cell lymphoma-2 expression, enhanced Bcl-2-associated death promoter (Bad) translocation from the cytoplasm to the mitochondria, and reduced Bad phosphorylation at Ser112. These effects were accompanied by increased cleavage of caspase 3 and poly-ADP-ribose-polymerase. In addition, combined SFN and Myr treatment significantly decreased the protein expression levels of phosphorylated AKT serine/threonine kinase 1 (Akt) at Ser473, as well as the phosphorylation of the downstream protein ribosomal protein, S6 kinase β-1. Therefore, SFN plus Myr was a more potent inducer of apoptosis in 3T3-L1 adipocytes than either compound alone. The results of the present study suggest that the mechanism of SNF/Myr-induced apoptosis involved activation of the Akt-mediated mitochondrial apoptotic pathway. This may aid treatment of animal models of obesity and preclinical testing.

HDAC inhibition as a treatment concept to combat temsirolimus-resistant bladder cancer cells

Introduction

Although the mechanistic target of rapamycin (mTOR) might be a promising molecular target to treat advanced bladder cancer, resistance develops under chronic exposure to an mTOR inhibitor (everolimus, temsirolimus). Based on earlier studies, we proposed that histone deacetylase (HDAC) blockade might circumvent resistance and investigated whether HDAC inhibition has an impact on growth of bladder cancer cells with acquired resistance towards temsirolimus.

Results

The HDAC inhibitor valproic acid (VPA) significantly inhibited growth, proliferation and caused G0/G1 phase arrest in RT112^res and UMUC-3^res. cdk1, cyclin B, cdk2, cyclin A and Skp1 p19 were down-regulated, p27 was elevated. Akt-mTOR signaling was deactivated, whereas acetylation of histone H3 and H4 in RT112^res and UMUC-3^res increased in the presence of VPA. Knocking down cdk2 or cyclin A resulted in a significant growth blockade of RT112^res and UMUC-3^res.

Materials And Methods

Parental (par) and resistant (res) RT112 and UMUC-3 cells were exposed to the HDAC inhibitor VPA. Tumor cell growth, proliferation, cell cycling and expression of cell cycle regulating proteins were then evaluated. siRNA blockade was used to investigate the functional impact of the proteins.

Conclusions

HDAC inhibition induced a strong response of temsirolimus-resistant bladder cancer cells. Therefore, the temsirolimus-VPA-combination might be an innovative strategy for bladder cancer treatment.

A CARP-1 functional mimetic loaded vitamin E-TPGS micellar nano-formulation for inhibition of renal cell carcinoma

Current treatments for Renal Cell Carcinoma (RCC) include a combination of surgery, targeted therapy, and immunotherapy. Emergence of resistant RCCs contributes to failure of drugs and poor prognosis, and thus warrants development of new and improved treatment options for RCCs. Here we generated and characterized RCC cells that are resistant to Everolimus, a frontline mToR-targeted therapy, and tested whether our novel class of CARP-1 functional mimetic (CFM) compounds inhibit parental and Everolimus-resistant RCC cells. CFMs inhibited RCC cell viability in a dose-dependent manner that was comparable to Everolimus treatments. The GI₅₀ dose of Everolimus for parental A498 cells was ∼1.2μM while it was <0.02μM for the parental UOK262 and UOK268 cells. The GI₅₀ dose for Everolimus-resistant A498, UOK262, and UOK268 cells were ≥10.0μM, 1.8-7.0μM, and 7.0-≥10.0μM, respectively. CFM-4 and its novel analog CFM-4.16 inhibited viabilities of Everolimus resistant RCC cells albeit CFM-4.16 was more effective than CFM-4. CFM-dependent loss of RCC cell viabilities was due in part to reduced cyclin B1 levels, activation of pro-apoptotic, stress-activated protein kinases (SAPKs), and apoptosis. CFM-4.16 suppressed growth of resistant RCC cells in three-dimensional suspension cultures. However, CFMs are hydrophobic and their intravenous administration and dose escalation for in-vivo studies remain challenging. In this study, we encapsulated CFM-4.16 in Vitamin-E TPGS-based- nanomicelles that resulted in its water-soluble formulation with higher CFM-4.16 loading (30% w/w). This CFM-4.16 formulation inhibited viability of parental and Everolimus-resistant RCC cells in vitro, and suppressed growth of parental A498 RCC-cell-derived xenografts in part by stimulating apoptosis. These findings portent promising therapeutic potential of CFM-4.16 for treatment of RCCs.