Tetra-O-Methyl Nordihydroguaiaretic Acid Broadly Suppresses Cancer Metabolism and Synergistically Induces Strong Anticancer Activity in Combination with Etoposide, Rapamycin and UCN-01

Bioelectric pharmacology of cancer: A systematic review of ion channel drugs affecting the cancer phenotype

Cancer is a pernicious and pressing medical problem; moreover, it is a failure of multicellular morphogenesis that sheds much light on evolutionary developmental biology. Numerous classes of pharmacological agents have been considered as cancer therapeutics and evaluated as potential carcinogenic agents; however, these are spread throughout the primary literature. Here, we briefly review recent work on ion channel drugs as promising anti-cancer treatments and present a systematic review of the known cancer-relevant effects of 109 drugs targeting ion channels. The roles of ion channels in cancer are consistent with the importance of bioelectrical parameters in cell regulation and with the functions of bioelectric signaling in morphogenetic signals that act as cancer suppressors. We find that compounds that are well-known for having targets in the nervous system, such as voltage-gated ion channels, ligand-gated ion channels, proton pumps, and gap junctions are especially relevant to cancer. Our review suggests further opportunities for the repurposing of numerous promising candidates in the field of cancer electroceuticals.

Interaction and Collaboration of SP1, HIF-1, and MYC in Regulating the Expression of Cancer-Related Genes to Further Enhance Anticancer Drug Development

Specificity protein 1 (SP1), hypoxia-inducible factor 1 (HIF-1), and MYC are important transcription factors (TFs). SP1, a constitutively expressed housekeeping gene, regulates diverse yet distinct biological activities; MYC is a master regulator of all key cellular activities including cell metabolism and proliferation; and HIF-1, whose protein level is rapidly increased when the local tissue oxygen concentration decreases, functions as a mediator of hypoxic signals. Systems analyses of the regulatory networks in cancer have shown that SP1, HIF-1, and MYC belong to a group of TFs that function as master regulators of cancer. Therefore, the contributions of these TFs are crucial to the development of cancer. SP1, HIF-1, and MYC are often overexpressed in tumors, which indicates the importance of their roles in the development of cancer. Thus, proper manipulation of SP1, HIF-1, and MYC by appropriate agents could have a strong negative impact on cancer development. Under these circumstances, these TFs have naturally become major targets for anticancer drug development. Accordingly, there are currently many SP1 or HIF-1 inhibitors available; however, designing efficient MYC inhibitors has been extremely difficult. Studies have shown that SP1, HIF-1, and MYC modulate the expression of each other and collaborate to regulate the expression of numerous genes. In this review, we provide an overview of the interactions and collaborations of SP1, HIF1A, and MYC in the regulation of various cancer-related genes, and their potential implications in the development of anticancer therapy.

Tetra-O-methyl-nordihydroguaiaretic acid inhibits energy metabolism and synergistically induces anticancer effects with temozolomide on LN229 glioblastoma tumors implanted in mice while preventing obesity in normal mice that consume high-fat diets

Tetra-O-methyl-nordihydroguaiaretic acid (terameprocol; M4N), a global transcription inhibitor, in combination with a second anticancer drug induces strong tumoricidal activity and has the ability to suppress energy metabolism in cultured cancer cells. In this study, we showed that after continuous oral consumption of high-fat (HF) diets containing M4N, the M4N concentration in most of the organs in mice reached ~1 μM (the M4N concentration in intestines and fat pads was as high as 20-40 μM) and treatment with the combination of M4N with temozolomide (TMZ) suppressed glycolysis and the tricarboxylic acid cycle in LN229 human glioblastoma implanted in xenograft mice. Combination treatment of M4N with TMZ also reduced the levels of lactate dehydrogenase A (LDHA), a key enzyme for glycolysis; lactate, a product of LDHA-mediated enzymatic activity; nicotinamide phosphoribosyltransferase, a rate-limiting enzyme for nicotinamide adenine dinucleotide plus hydrogen (NADH)/NAD+ salvage pathway; and NAD+, a redox electron carrier essential for energy metabolism. It was also shown that M4N suppressed oxygen consumption in cultured LN229 cells, indicating that M4N inhibited oxidative phosphorylation. Treatment with M4N and TMZ also decreased the level of hypoxia-inducible factor 1A, a major regulator of LDHA, under hypoxic conditions. The ability of M4N to suppress energy metabolism resulted in induction of the stress-related proteins activating transcription factor 4 and cation transport regulator-like protein 1, and an increase in reactive oxygen species production. In addition, the combination treatment of M4N with TMZ reduced the levels of oncometabolites such as 2-hydroxyglutarate as well as the aforementioned lactate. M4N also induced methylidenesuccinic acid (itaconate), a macrophage-specific metabolite with anti-inflammatory activity, in tumor microenvironments. Meanwhile, the ability of M4N to suppress energy metabolism prevented obesity in mice consuming HF diets, indicating that M4N has beneficial effects on normal tissues. The dual ability of combination treatment with M4N to suppress both energy metabolism and oncometabolites shows that it is potentially an effective therapy for cancer.

iDMET: network-based approach for integrating differential analysis of cancer metabolomics

BACKGROUND

Comprehensive metabolomic analyses have been conducted in various institutes and a large amount of metabolomic data are now publicly available. To help fully exploit such data and facilitate their interpretation, metabolomic data obtained from different facilities and different samples should be integrated and compared. However, large-scale integration of such data for biological discovery is challenging given that they are obtained from various types of sample at different facilities and by different measurement techniques, and the target metabolites and sensitivities to detect them also differ from study to study.

RESULTS

We developed iDMET, a network-based approach to integrate metabolomic data from different studies based on the differential metabolomic profiles between two groups, instead of the metabolite profiles themselves. As an application, we collected cancer metabolomic data from 27 previously published studies and integrated them using iDMET. A pair of metabolomic changes observed in the same disease from two studies were successfully connected in the network, and a new association between two drugs that may have similar effects on the metabolic reactions was discovered.

CONCLUSIONS

We believe that iDMET is an efficient tool for integrating heterogeneous metabolomic data and discovering novel relationships between biological phenomena.

Metabolic control of cancer progression as novel targets for therapy

Metabolism is an important part of tumorigenesis as well as progression. The various cancer metabolism pathways, such as glucose metabolism and glutamine metabolism, directly regulate the development and progression of cancer. The pathways by which the cancer cells rewire their metabolism according to their needs, surrounding environment and host tissue conditions are an important area of study. The regulation of these metabolic pathways is determined by various oncogenes, tumor suppressor genes, as well as various constituent cells of the tumor microenvironment. Expanded studies on metabolism will help identify efficient biomarkers for diagnosis and strategies for therapeutic interventions and countering ways by which cancers may acquire resistance to therapy.

Perspectives on the Clinical Development of NRF2-Targeting Drugs

The transcription factor NRF2 (nuclear factor erythroid 2-related factor 2) triggers homeostatic responses against a plethora of environmental or endogenous deviations in redox metabolism, inflammation, proteostasis, etc. Therefore, pharmacological activation of NRF2 is a promising therapeutic strategy for several chronic diseases that are underlined by low-grade oxidative inflammation and dysregulation of redox metabolism, such as neurodegenerative, cardiovascular, and metabolic diseases. While NRF2 activation is useful in inhibiting carcinogenesis, its inhibition is needed in constituted tumors where NRF2 provides a survival advantage in the challenging tumor niche. This review describes the electrophilic and non-electrophilic NRF2 activators with clinical projection in various chronic diseases. We also analyze the status of NRF2 inhibitors, which are for the moment in a proof-of-concept stage. Advanced in silico screening and medicinal chemistry are expected to provide new or repurposing small molecules with increased potential for fostering the development of targeted NRF2 modulators. The nuclear factor erythroid 2 (NFE2)-related factor 2 (NRF2) is rapidly degraded by proteasomes under a basal condition in a Keap1-dependent manner. ROS oxidatively modifies Keap1 to release NRF2 and allow its nuclear translocation. Here it binds to the antioxidant response element to regulate gene transcription. An alternative mechanism controlling NRF2 stability is glycogen synthase kinase 3 (GSK-3)-induced phosphorylation. Indicated in blue are NRF2-activating and NRF2-inhibiting drugs.

The role of RICTOR amplification in targeted therapy and drug resistance

The emergence of tyrosine kinase inhibitors (TKIs) has changed the current treatment paradigm and achieved good results in recent decades. However, an increasing number of studies have indicated that the complex network of receptor tyrosine kinase (RTK) co-activation could influence the characteristic phenotypes of cancer and the tumor response to targeted treatments. One of strategies to blocking RTK co-activation is targeting the downstream factors of RTK, such as PI3K-AKT-mTOR pathway. RICTOR, a core component of mTORC2, acts as a key effector molecule of the PI3K-AKT pathway; its amplification is often associated with poor clinical outcomes and resistance to TKIs. Here, we discuss the biology of RICTOR in tumor and the prospects of targeting RICTOR as a complementary therapy to inhibit RTK co-activation.

Autophagy in Human Health and Disease: Novel Therapeutic Opportunities

SIGNIFICANCE

In eukaryotes, autophagy represents a highly evolutionary conserved process, through which macromolecules and cytoplasmic material are degraded into lysosomes and recycled for biosynthetic or energetic purposes. Dysfunction of the autophagic process has been associated with the onset and development of many human chronic pathologies, such as cardiovascular, metabolic, and neurodegenerative diseases as well as cancer. Recent Advances: Currently, comprehensive research is being carried out to discover new therapeutic agents that are able to modulate the autophagic process in vivo. Recent evidence has shown that a large number of natural bioactive compounds are involved in the regulation of autophagy by modulating several transcriptional factors and signaling pathways.

CRITICAL ISSUES

Critical issues that deserve particular attention are the inadequate understanding of the complex role of autophagy in disease pathogenesis, the limited availability of therapeutic drugs, and the lack of clinical trials. In this context, the effects that natural bioactive compounds exert on autophagic modulation should be clearly highlighted, since they depend on the type and stage of the pathological conditions of diseases.

FUTURE DIRECTIONS

Research efforts should now focus on understanding the survival-supporting and death-promoting roles of autophagy, how natural compounds interact exactly with the autophagic targets so as to induce or inhibit autophagy and on the evaluation of their pharmacological effects in a more in-depth and mechanistic way. In addition, clinical studies on autophagy-inducing natural products are strongly encouraged, also to highlight some fundamental aspects, such as the dose, the duration, and the possible synergistic action of these compounds with conventional therapy.

Antitumor Effects of Nordihydroguaiaretic Acid (NDGA) in Bladder T24 Cancer Cells are Related to Increase in ROS Production and Mitochondrial Leak Respiration

The aim of this study was to evaluate the effect of nordihydroguaiaretic acid (NDGA) on tumor bladder T24 cells. Bladder cancer T24 cells were cultured on Dulbecco's Modified Eagle Medium in presence of NDGA. Cell viability and apoptosis were evaluated after 24, 48 and 72 h by using fluorescein diacetate (FDA) and Alexa fluor 488 annexin-V/propidium iodide solution, respectively. To determine the mitochondrial effects of NDGA (0-24 h), reactive oxygen species (ROS) levels by dihydroethidium fluorescence, mitochondrial membrane potential (ΔΨm) by 5,5’,6,6'-tetrachloro-1,1’,3,3'-tetraethyl-imidacarbocyanine iodide (JC-1) dual fluorescence and cellular respiration states by high resolution respirometry were evaluated. It was found that NDGA reduced T24 cell viability after 72 h of incubation in a concentration-dependent manner and apoptosis increased at 48 h. Furthermore, 20 μM NDGA increased ROS levels, decreased ΔΨm and promoted leak of respiration from mitochondrial respiratory chain in T24 cells which was associated to the death of tumor cells. Taken together these results suggested that antitumor effects of NDGA in T24 cells are related to its ability to induce mitochondrial alteration.

The combination of everolimus and terameprocol exerts synergistic antiproliferative effects in endometrial cancer: molecular role of insulin-like growth factor binding protein 2

Oncogenic PIK3CA mutations are common in endometrial cancers, and the PI3K/AKT/mTOR pathway is targetable by drugs. We sought to investigate whether the combination of an mTOR inhibitor, everolimus (RAD001), and an AKT inhibitor, terameprocol (M4N), exerts better antiproliferative effects in endometrial cancer. The molecular mechanisms underlying their pharmacological action were also examined. The combination of RAD001 and M4N exerted in vitro synergistic effects on cell viability, apoptosis, and expression of IGFBP2 in endometrial cancer cells. Mechanistically, the Sp1 site on the IGFBP2 promoter was required for RAD001- and M4N-induced downregulation. IGFBP2 protein expression was higher in endometrial cancer than in the normal endometrium (P < 0.001). Furthermore, elevated IGFBP2 histoscores were significantly associated with a lower overall survival (P = 0.021). In conclusion, our in vitro results demonstrate that RAD001 and M4N exert synergistic antiproliferative effects against endometrial cancer cells, which appeared to be mediated by the inhibition of IGFBP2, a key anti-apoptotic regulator. Further clinical studies of this drug combination in patients with endometrial cancer may be warranted, especially in the presence of PIK3CA and IGFBP2 aberrations. KEY MESSAGES: RAD001 and M4N synergistically suppress endometrial cancer growth. IGFBP2 is overexpressed in endometrial cancer. The combination of RAD001 and M4N significantly reduces IGFBP2 overexpression. Sp1 binding site on the IGFBP2 promoter is required for RAD001- and M4N-induced downregulation. High IGFBP2 histoscore in endometrial cancer portends a poor prognosis.

Development of a novel prognostic score for breast cancer patients using mRNA expression of CHAC1

AIM

To develop a prognostic score for primary breast cancer patients integrating conventional predictors and the novel biomarker CHAC1 to aid adjuvant chemotherapy decisions.

PATIENTS & METHODS

A prognostic score for overall survival was developed using: conventional predictors from a dataset of 1777 patients and the weight of CHAC1 mRNA expression from an independent dataset of 106 patients using multivariate Cox regression.

RESULTS

The new score includes: CHAC1 mRNA expression, age, tumor size, HER2 neu status, lymph node status and degree of malignancy. Using a cut-off value of 11 score points, 10-year survival was 82% in low-risk (n = 34) and 43% in high-risk patients (n = 72). The addition of CHAC1 resulted in 16% reclassification.

CONCLUSION

Including CHAC1 in prognostic prediction may aid (and change) personalized treatment selection.

Antiviral Activity of Nordihydroguaiaretic Acid and Its Derivative Tetra-O-Methyl Nordihydroguaiaretic Acid against West Nile Virus and Zika Virus

Flaviviruses are positive-strand RNA viruses distributed all over the world that infect millions of people every year and for which no specific antiviral agents have been approved. These viruses include the mosquito-borne West Nile virus (WNV), which is responsible for outbreaks of meningitis and encephalitis. Considering that nordihydroguaiaretic acid (NDGA) has been previously shown to inhibit the multiplication of the related dengue virus and hepatitis C virus, we have evaluated the effect of NDGA, and its methylated derivative tetra-O-methyl nordihydroguaiaretic acid (M₄N), on the infection of WNV. Both compounds inhibited the infection of WNV, likely by impairing viral replication. Since flavivirus multiplication is highly dependent on host cell lipid metabolism, the antiviral effect of NDGA has been previously related to its ability to disturb the lipid metabolism, probably by interfering with the sterol regulatory element-binding proteins (SREBP) pathway. Remarkably, we observed that other structurally unrelated inhibitors of the SREBP pathway, such as PF-429242 and fatostatin, also reduced WNV multiplication, supporting that the SREBP pathway may constitute a druggable target suitable for antiviral intervention against flavivirus infection. Moreover, treatment with NDGA, M₄N, PF-429242, and fatostatin also inhibited the multiplication of the mosquito-borne flavivirus Zika virus (ZIKV), which has been recently associated with birth defects (microcephaly) and neurological disorders. Our results point to SREBP inhibitors, such as NDGA and M₄N, as potential candidates for further antiviral development against medically relevant flaviviruses.

Drugs currently under investigation for the treatment of invasive candidiasis

INTRODUCTION

The widespread implementation of immunosuppressants, immunomodulators, hematopoietic stem cell transplantation and solid organ transplantation in clinical practice has led to an expanding population of patients who are at risk for invasive candidiasis, which is the most common form of fungal disease among hospitalized patients in the developed world. The emergence of drug-resistant Candida spp. has added to the morbidity associated with invasive candidiasis and novel therapeutic strategies are urgently needed. Areas covered: In this paper, we explore investigational agents for the treatment of invasive candidiasis, with particular attention paid to compounds that have recently entered phase I or phase II clinical trials. Expert opinion: The antifungal drug development pipeline has been severely limited due to regulatory hurdles and a systemic lack of investment in novel compounds. However, several promising drug development strategies have recently emerged, including chemical screens involving Pathogen Box compounds, combination antifungal therapy, and repurposing of existing agents that were initially developed to treat other conditions, all of which have the potential to redefine the treatment of invasive candidiasis.

Targeting survivin for therapeutic discovery: past, present, and future promises

Survivin, the smallest member of the inhibitor of apoptosis protein (IAP) family, is overexpressed in cells of almost all cancers but not in most normal tissues in adults. Survivin expression is required for cancer cell survival and knocking down its expression or inhibiting its function using molecular approaches results in spontaneous apoptosis. Thus, survivin is an attractive and perhaps ideal target for cancer drug discovery. However, a US Food and Drug Administration (FDA)-approved drug targeting survivin has yet to emerge. In this Foundation Review, we examine and evaluate various strategies that have been used to target survivin and the stages of each survivin inhibitor to help understand this lack of success. We also provide future perspectives moving forward in targeting survivin for drug discovery.

Glyoxalase 2 drives tumorigenesis in human prostate cells in a mechanism involving androgen receptor and p53-p21 axis

Glyoxalase 2 (Glo2), a metabolic enzyme, is overexpressed in some human cancers which suggests this enzyme may play a role in human tumorigenesis. In prostate cancer (PCa), the role of Glo2 has been scarcely investigated and there are no studies addressing a causative involvement of this protein in this neoplasia. Here, we examined the immunohistochemical profile of Glo2 in human PCa and benign adjacent tissues and investigated Glo2 involvement in PCa development in human prostate cell lines. PCa and matched adjacent normal tissues were obtained from paraffin sections of primary PCa from 20 patients who had undergone radical prostatectomy. Histopathological diagnosis was confirmed for each sample. Glo2 expression analysis was performed by immunohistochemistry in prostate tissues, and by qRT-PCR and immunoblotting in prostate cell lines. The causative and mechanistic role of Glo2 in prostate tumorigenesis was demonstrated by Glo2 ectopic expression/silencing and employing specific activators/inhibitors. Our results showed that Glo2 was selectively expressed in PCa but not in the luminal compartment of the adjacent benign epithelium consistently in all the examined 20 cases. Glo2 expression in PCa was dependent on androgen receptor (AR) and was aimed at stimulating cell proliferation and eluding apoptosis through a mechanism involving the p53-p21 axis. Glo2 was intensely expressed in the basal cells of benign glands but was not involved in PCa genesis. Our results demonstrate for the first time that Glo2 drives prostate tumorigenesis and suggest that it may represent a novel adjuvant marker in the pathological diagnosis of early PCa.

Anti-anaphylactic action of nordihydroguaiaretic acid in antigen sensitized guinea pigs

Therapeutic natural products and medicinal herbs has gained popularity. The anti-antigenic action of the plant alkaloid nordihydroguaiaretic acid (NDGA) was studied in ovalbumin (OA)-sensitized guinea pigs. In one series of experiments conscious, non-sedated guinea pigs were challenged with OA aerosol. Specific airway resistance (SR_AW) was monitored using a two-chambered whole-body plethysmograph. OA aerosol increased SR_AW above that produced by vehicle administration. Prior NDGA administration by a 1min 0.9% aerosol (w/vol) attenuated the increase in SR_AW resulting from OA challenge. In the anesthetized guinea pig pretreated with indomethacin, pyrilamine and propranolol, intravenous OA injection increased intra-tracheal pressure above vehicle injection. Intravenous NDGA administration (5mg/kg) reduced the intra-tracheal pressure increases. In a third series of experiments plasma leukotriene C₄ was measured by radio-immunoassay in 3 groups challenged with OA aerosol: vehicle-treated OA-sensitized, OA-sensitized receiving NDGA and vehicle treated guinea pigs. NDGA pretreatment reduced plasma LTC₄ in response to OA challenge in OA sensitized guinea pigs. This study demonstrates that NDGA is an effective antigenic agent when given by aerosol or intravenous injection in either conscious or anesthetized guinea pigs, respectively. The mechanism of action of NDGA is presumed primarily be due to the blockage of 5-lipoxygenase and therefore the synthesis of leukotrienes.

An overview of rapamycin: from discovery to future perspectives

Rapamycin is an immunosuppressive metabolite produced from several actinomycete species. Besides its immunosuppressive activity, rapamycin and its analogs have additional therapeutic potentials, including antifungal, antitumor, neuroprotective/neuroregenerative, and lifespan extension activities. The core structure of rapamycin is derived from (4R,5R)-4,5-dihydrocyclohex-1-ene-carboxylic acid that is extended by polyketide synthase. The resulting linear polyketide chain is cyclized by incorporating pipecolate and further decorated by post-PKS modification enzymes. Herein, we review the discovery and biological activities of rapamycin as well as its mechanism of action, mechanistic target, biosynthesis, and regulation. In addition, we introduce the many efforts directed at enhancing the production of rapamycin and generating diverse analogs and also explore future perspectives in rapamycin research. This review will also emphasize the remarkable pilot studies on the biosynthesis and production improvement of rapamycin by Dr. Demain, one of the world's distinguished scientists in industrial microbiology and biotechnology.