Alternations of NF-κB Signaling by Natural Compounds in Muscle-Derived Cancers.

The NF-κB-signaling pathway plays a crucial role in cancer progression, including muscle-derived cancers such as rhabdomyosarcoma or sarcoma. Several natural compounds have been studied for their ability to alter NF-κB signaling in these types of cancers. This review paper summarizes the current knowledge on the effects of natural compounds, including curcumin, resveratrol, quercetin, epigallocatechin-3-gallate, and berberine, on NF-κB signaling in muscle-derived cancers. These compounds have been shown to inhibit NF-κB signaling in rhabdomyosarcoma cells through various mechanisms, such as inhibiting the activation of the IKK complex and the NF-κB transcription factor. These findings suggest that natural compounds could be potential therapeutic agents for muscle-derived cancers. However, further research is needed to fully understand their mechanisms of action and potential clinical applications.

Wild type and gain of function mutant TP53 can regulate the sensitivity of pancreatic cancer cells to chemotherapeutic drugs, EGFR/Ras/Raf/MEK, and PI3K/mTORC1/GSK-3 pathway inhibitors, nutraceuticals and alter metabolic properties.

TP53 is a master regulator of many signaling and apoptotic pathways involved in: aging, cell cycle progression, gene regulation, growth, apoptosis, cellular senescence, DNA repair, drug resistance, malignant transformation, metastasis, and metabolism. Most pancreatic cancers are classified as pancreatic ductal adenocarcinomas (PDAC). The tumor suppressor gene TP53 is mutated frequently (50-75%) in PDAC. Different types of TP53 mutations have been observed including gain of function (GOF) point mutations and various deletions of the TP53 gene resulting in lack of the protein expression. Most PDACs have point mutations at the KRAS gene which result in constitutive activation of KRas and multiple downstream signaling pathways. It has been difficult to develop specific KRas inhibitors and/or methods that result in recovery of functional TP53 activity. To further elucidate the roles of TP53 in drug-resistance of pancreatic cancer cells, we introduced wild-type (WT) TP53 or a control vector into two different PDAC cell lines. Introduction of WT-TP53 increased the sensitivity of the cells to multiple chemotherapeutic drugs, signal transduction inhibitors, drugs and nutraceuticals and influenced key metabolic properties of the cells. Therefore, TP53 is a key molecule which is critical in drug sensitivity and metabolism of PDAC.

Effects of the Mutant TP53 Reactivator APR-246 on Therapeutic Sensitivity of Pancreatic Cancer Cells in the Presence and Absence of WT-TP53.

The TP53 tumor suppressor is mutated in ~75% of pancreatic cancers. The mutant TP53 protein in pancreatic ductal adenocarcinomas (PDAC) promotes tumor growth and metastasis. Attempts have been made to develop molecules that restore at least some of the properties of wild-type (WT) TP53. APR-246 is one such molecule, and it is referred to as a mutant TP53 reactivator. To understand the potential of APR-246 to sensitize PDAC cells to chemotherapy, we introduced a vector encoding WT-TP53 into two PDAC cell lines, one lacking the expression of TP53 (PANC-28) and one with a gain-of-function (GOF) mutant TP53 (MIA-PaCa-2). APR-246 increased drug sensitivity in the cells containing either a WT or mutant TP53 protein with GOF activity, but not in cells that lacked TP53. The introduction of WT-T53 into PANC-28 cells increased their sensitivity to the TP53 reactivator, chemotherapeutic drugs, and signal transduction inhibitors. The addition of WT-TP53 to PDAC cells with GOF TP53 also increased their sensitivity to the drugs and therapeutics, indicating that APR-246 could function in cells with WT-TP53 and GOF TP53. These results highlight the importance of knowledge of the type of TP53 mutation that is present in cancer patients before the administration of drugs which function through the reactivation of TP53.

APR-246-The Mutant TP53 Reactivator-Increases the Effectiveness of Berberine and Modified Berberines to Inhibit the Proliferation of Pancreatic Cancer Cells.

Pancreatic ductal adenocarcinoma (PDAC) is the most common form of pancreatic cancer. In ~75% of PDAC, the tumor suppressor TP53 gene is mutated. Novel approaches to treat cancer involve compounds called mutant TP53 reactivators. They interact with mutant TP53 proteins and restore some of their growth suppressive properties, but they may also interact with other proteins, e.g., TP63 and TP73. We examined the ability of the TP53 reactivator APR-246 to interact with eleven modified berberine compounds (NAX compounds) in the presence and absence of WT-TP53 in two PDAC cell lines: the MIA-PaCa-2, which has gain of function (GOF) TP53 mutations on both alleles, and PANC-28, which lacks expression of the WT TP53 protein. Our results indicate the TP53 reactivator-induced increase in therapeutic potential of many modified berberines.

GSK3 as a Regulator of Cytoskeleton Architecture: Consequences for Health and Disease.

Glycogen synthase kinase 3 (GSK3) was initially isolated as a critical protein in energy metabolism. However, subsequent studies indicate that GSK-3 is a multi-tasking kinase that links numerous signaling pathways in a cell and plays a vital role in the regulation of many aspects of cellular physiology. As a regulator of actin and tubulin cytoskeleton, GSK3 influences processes of cell polarization, interaction with the extracellular matrix, and directional migration of cells and their organelles during the growth and development of an animal organism. In this review, the roles of GSK3-cytoskeleton interactions in brain development and pathology, migration of healthy and cancer cells, and in cellular trafficking of mitochondria will be discussed.

GSK-3ß Can Regulate the Sensitivity of MIA-PaCa-2 Pancreatic and MCF-7 Breast Cancer Cells to Chemotherapeutic Drugs, Targeted Therapeutics and Nutraceuticals.

Glycogen synthase kinase-3 (GSK-3) is a regulator of signaling pathways. KRas is frequently mutated in pancreatic cancers. The growth of certain pancreatic cancers is KRas-dependent and can be suppressed by GSK-3 inhibitors, documenting a link between KRas and GSK-3. To further elucidate the roles of GSK-3ß in drug-resistance, we transfected KRas-dependent MIA-PaCa-2 pancreatic cells with wild-type (WT) and kinase-dead (KD) forms of GSK-3ß. Transfection of MIA-PaCa-2 cells with WT-GSK-3ß increased their resistance to various chemotherapeutic drugs and certain small molecule inhibitors. Transfection of cells with KD-GSK-3ß often increased therapeutic sensitivity. An exception was observed with cells transfected with WT-GSK-3ß and sensitivity to the BCL2/BCLXL ABT737 inhibitor. WT-GSK-3ß reduced glycolytic capacity of the cells but did not affect the basal glycolysis and mitochondrial respiration. KD-GSK-3ß decreased both basal glycolysis and glycolytic capacity and reduced mitochondrial respiration in MIA-PaCa-2 cells. As a comparison, the effects of GSK-3 on MCF-7 breast cancer cells, which have mutant PIK3CA, were examined. KD-GSK-3ß increased the resistance of MCF-7 cells to chemotherapeutic drugs and certain signal transduction inhibitors. Thus, altering the levels of GSK-3ß can have dramatic effects on sensitivity to drugs and signal transduction inhibitors which may be influenced by the background of the tumor.

Sensitivity of pancreatic cancer cells to chemotherapeutic drugs, signal transduction inhibitors and nutraceuticals can be regulated by WT-TP53.

Pancreatic ductal adenocarcinoma (PDAC) is a highly metastatic malignancy. Approximately 85% of pancreatic cancers are classified as PDACs. The survival of PDAC patients is very poor and only 5-10% of patients survive 5 years after diagnosis. Mutations at the KRAS and TP53 gene are frequently observed in PDAC patients. The PANC-28 cell line lacks wild-type (WT) TP53. In the following study, we have investigated the effects of restoration of WT TP53 activity on the sensitivity of PANC-28 pancreatic cancer cells to various drugs which are used to treat PDAC patients as well as other cancer patients. In addition, we have examined the effects of signal transduction inhibitors which target critical pathways frequently deregulated in cancer. The effects of the anti-diabetes drug metformin and the anti-malarial drug chloroquine were also examined as these drugs may be repurposed to treat other diseases. Finally, the effects of certain nutraceuticals which are used to treat various ailments were also examined. Introduction of WT-TP53 activity in PANC-28 PDAC cells, can increase their sensitivity to various drugs. Attempts are being made clinically to increase TP53 activity in various cancer types which will often inhibit cell growth by multiple mechanisms.

GSK-3 and miRs: Master regulators of therapeutic sensitivity of cancer cells.

Glycogen synthetase kinase-3 (GSK-3) and microRNAs (miRs) affect many critical signaling pathways important in cell growth. GSK-3 is a serine/threonine (S/T) protein kinase. Often when GSK-3 phosphorylates other proteins, they are inactivated and the signaling pathway is shut down. The PI3K/PTEN/AKT/GSK3/mTORC1 pathway plays key roles in regulation of cell growth, apoptosis, drug resistance, malignant transformation and metastasis and is often deregulated in cancer. When GSK-3 is phosphorylated by AKT it is inactivated and this often leads to growth promotion. When GSK-3 is not phosphorylated by AKT or other kinases at specific negative-regulatory residues, it can modify the activity of many proteins by phosphorylation, some of these proteins promote while others inhibit cell proliferation. This is part of the conundrum regarding GSK-3. The central theme of this review is the ability of GSK-3 to serve as either a tumor suppressor or a tumor promoter in cancer which is likely due to its diverse protein substrates. The effects of multiple miRs which bind mRNAs encoding GSK-3 and other signaling molecules and how they affect cell growth and sensitivity to various therapeutics will be discussed as they serve to regulate GSK-3 and other proteins important in controlling proliferation.

Targeting GSK3 and Associated Signaling Pathways Involved in Cancer.

Glycogen synthase kinase 3 (GSK-3) is a serine/threonine (S/T) protein kinase. Although GSK-3 originally was identified to have functions in regulation of glycogen synthase, it was subsequently determined to have roles in multiple normal biochemical processes as well as various disease conditions. GSK-3 is sometimes referred to as a moonlighting protein due to the multiple substrates and processes which it controls. Frequently, when GSK-3 phosphorylates proteins, they are targeted for degradation. GSK-3 is often considered a component of the PI3K/PTEN/AKT/GSK-3/mTORC1 pathway as GSK-3 is frequently phosphorylated by AKT which regulates its inactivation. AKT is often active in human cancer and hence, GSK-3 is often inactivated. Moreover, GSK-3 also interacts with WNT/ß-catenin signaling and ß-catenin and other proteins in this pathway are targets of GSK-3. GSK-3 can modify NF-κB activity which is often expressed at high levels in cancer cells. Multiple pharmaceutical companies developed small molecule inhibitors to suppress GSK-3 activity. In addition, various natural products will modify GSK-3 activity. This review will focus on the effects of small molecule inhibitors and natural products on GSK-3 activity and provide examples where these compounds were effective in suppressing cancer growth.

GSK3 and miRNA in neural tissue: From brain development to neurodegenerative diseases.

MicroRNAs (miRs) are small RNAs modulating gene expression and creating intricate regulatory networks that are dysregulated in many pathological states, including neurodegenerative disorders. In silico analyses denote a multifunctional kinase glycogen synthase kinase-3 (GSK3) as a putative target of numerous miRs identified in neural tissue. GSK3 is engaged in almost all aspects of neuronal development and functioning. Moreover, there is an autoregulatory feedback between GSK3 and miRNAs as the kinase can influence biogenesis of miRs. Members of the miR-GSK3 axes might thus represent convenient therapeutic targets in neuropathologies that display its abnormal regulation. This review summarizes the present knowledge about direct interactions of GSK3 and miRs in brain, and their putative roles in pathogenesis of neurodegenerative and neuropsychiatric disorders. This article is part of a Special Issue entitled: GSK-3 and related kinases in cancer, neurological and other disorders edited by James McCubrey, Agnieszka Gizak and Dariusz Rakus.

The Reverse Warburg Effect is Associated with Fbp2-Dependent Hif1α Regulation in Cancer Cells Stimulated by Fibroblasts.

Fibroblasts are important contributors to cancer development. They create a tumor microenvironment and modulate our metabolism and treatment resistance. In the present paper, we demonstrate that healthy fibroblasts induce metabolic coupling with non-small cell lung cancer cells by down-regulating the expression of glycolytic enzymes in cancer cells and increasing the fibroblasts' ability to release lactate and thus support cancer cells with energy-rich glucose-derived metabolites, such as lactate and pyruvate-a process known as the reverse Warburg effect. We demonstrate that these changes result from a fibroblasts-stimulated increase in the expression of fructose bisphosphatase (Fbp) in cancer cells and the consequent modulation of Hif1α function. We show that, in contrast to current beliefs, in lung cancer cells, the predominant and strong interaction with the Hif1α form of Fbp is not the liver (Fbp1) but in the muscle (Fbp2) isoform. Since Fbp2 oligomerization state and thus, its role is regulated by AMP and NAD+-crucial indicators of cellular metabolic conditions-we hypothesize that the Hif1α-dependent regulation of the metabolism in cancer is modulated through Fbp2, a sensor of the energy and redox state of a cell.

Abilities of ß-Estradiol to interact with chemotherapeutic drugs, signal transduction inhibitors and nutraceuticals and alter the proliferation of pancreatic cancer cells.

Improving the effects of chemotherapy and reducing the side effects are important goals in cancer research. Various approaches have been examined to enhance the effectiveness of chemotherapy. For example, signal transduction inhibitors or hormonal based approaches have been included with chemo- or radio-therapy. MIA-PaCa-2 and BxPC-3 pancreatic ductal adenocarcinoma (PDAC) cells both express the estrogen receptor (ER). The effects of ß-estradiol on the growth of PDAC cells has not been examined yet the ER is expressed in PDAC cells. We have examined the effects of combining ß-estradiol with chemotherapeutic drugs, signal transcription inhibitors, natural products and nutraceuticals on PDAC. In most cases, inclusion of ß-estradiol with chemotherapeutic drugs increased chemosensitivity. These results indicate some approaches involving ß-estradiol which may be used to increase the effectiveness of chemotherapeutic and other drugs on the growth of PDAC.

Targeting a moonlighting function of aldolase induces apoptosis in cancer cells.

Muscle fructose-1,6-bisphosphate aldolase (ALDOA) is among the most abundant glycolytic enzymes in all cancer cells. Here, we show that the enzyme plays a previously unknown and critical role in a cancer cell survival. Simultaneous inhibition of ALDOA activity and interaction with F-actin cytoskeleton using ALDOA slow-binding inhibitor UM0112176 leads to a rapid cofilin-dependent loss of F-actin stress fibers which is associated with elevated ROS production, inhibition of ATP synthesis, increase in calcium levels, caspase activation and arrested cellular proliferation. These effects can be reproduced by silencing of ALDOA. The mechanism of pharmacological action is, however, independent of the catalytic function of the enzyme, specific to cancer cells, and is most deleterious to cells undergoing the epithelial-mesenchymal transition, a process facilitating cancer cell invasion. Our results demonstrate that the overabundance of ALDOA in cancer cells is associated with its moonlighting rather than catalytic functions. This may have significant implications for development of novel broad-based anti-cancer therapies.

Abilities of berberine and chemically modified berberines to interact with metformin and inhibit proliferation of pancreatic cancer cells.

Pancreatic cancer is devastating cancer worldwide with few if any truly effective therapies. Pancreatic cancer has an increasing incidence and may become the second leading cause of death from cancer. Novel, more effective therapeutic approaches are needed as pancreatic cancer patients usually survive for less than a year after being diagnosed. Control of blood sugar levels by the prescription drug metformin in diseases such as diabetes mellitus has been examined in association with pancreatic cancer. While the clinical trials remain inconclusive, there is hope that certain diets and medications may affect positively the outcomes of patients with pancreatic and other cancers. Other natural compounds may share some of the effects of metformin. One "medicinal" fruit consumed by millions worldwide is berberine (BBR). Metformin and BBR both activate AMP-activated protein kinase (AMPK) which is a key mediator of glucose metabolism. Glucose metabolism has been shown to be very important in cancer and its significance is increasing. In the following studies, we have examined the effects of metformin, BBR and a panel of modified BBRs (NAX compounds) and chemotherapeutic drugs on the growth of four different human pancreatic adenocarcinoma cell lines (PDAC). Interestingly, the effects of metformin could be enhanced by BBR and certain modified BBRs. Upon restoration of WT-TP53 activity in MIA-PaCa-2 cells, an altered sensitivity to the combination of certain NAX compounds and metformin was observed compared to the parental cells which normally lack WT-TP53. Certain NAX compounds may interact with WT-TP53 and metformin treatment to alter the expression of key molecules involved in cell growth. These results suggest a therapeutic approach by combining certain pharmaceutical drugs and nutraceuticals to suppress the growth of cancer cells.

Abilities of berberine and chemically modified berberines to inhibit proliferation of pancreatic cancer cells.

Berberine (BBR) is a common nutraceutical consumed by millions worldwide. BBR has many different effects on human health, e.g., diabetes, diarrhea, inflammation and now more recently it has been proposed to have potent anti-cancer effects. BBR has been shown to suppress the growth of cancer cells more than normal cells. BBR has been proposed to exert its growth-inhibitory effects by many different biochemical mechanisms including: suppression of cell cycle progression, induction of reactive oxygen species, induction of apoptosis and autophagy and interactions with DNA potentially leading to DNA damage, and altered gene expression. Pancreatic cancer is a leading cancer worldwide associated with a poor prognosis. As our population ages, pancreatic cancer has an increasing incidence and will likely become the second leading cause of death from cancer. There are few truly-effective therapeutic options for pancreatic cancer. Surgery and certain chemotherapeutic drugs are used to treat pancreatic cancer patients. Novel approaches to treat pancreatic cancer patients are direly needed as they usually survive for less than a year after being diagnosed. In the following manuscript, we discuss the abilities of BBR and certain chemically-modified BBRs (NAX compounds) to suppress growth of pancreatic cancer cells.

Metformin influences drug sensitivity in pancreatic cancer cells.

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive, highly metastatic malignancy and accounts for 85% of pancreatic cancers. PDAC patients have poor prognosis with a five-year survival of only 5-10% after diagnosis and treatment. Pancreatic cancer has been associated with type II diabetes as the frequency of recently diagnosed diabetics that develop pancreatic cancer within a 10-year period of initial diagnosis of diabetes in increased in comparison to non-diabetic patients. Metformin is a very frequently prescribed drug used to treat type II diabetes. Metformin acts in part by stimulating AMP-kinase (AMPK) and results in the suppression of mTORC1 activity and the induction of autophagy. In the following studies, we have examined the effects of metformin in the presence of various chemotherapeutic drugs, signal transduction inhibitors and natural products on the growth of three different PDAC lines. Metformin, by itself, was not effective at suppressing growth of the pancreatic cancer cell lines at concentration less than 1000 nM, however, in certain PDAC lines, a suboptimal dose of metformin (250 nM) potentiated the effects of various chemotherapeutic drugs used to treat pancreatic cancer (e.g., gemcitabine, cisplatin, 5-fluorouracil) and other cancer types (e.g., doxorubicin, docetaxel). Furthermore, metformin could increase anti-proliferative effects of mTORC1 and PI3K/mTOR inhibitors as well as natural products such as berberine and the anti-malarial drug chloroquine in certain PDAC lines. Thus, metformin can enhance the effects of certain drugs and signal transduction inhibitors which are used to treat pancreatic and various other cancers.

Effects of berberine, curcumin, resveratrol alone and in combination with chemotherapeutic drugs and signal transduction inhibitors on cancer cells-Power of nutraceuticals.

Over the past fifty years, society has become aware of the importance of a healthy diet in terms of human fitness and longevity. More recently, the concept of the beneficial effects of certain components of our diet and other compounds, that are consumed often by different cultures in various parts of the world, has become apparent. These "healthy" components of our diet are often referred to as nutraceuticals and they can prevent/suppress: aging, bacterial, fungal and viral infections, diabetes, inflammation, metabolic disorders and cardiovascular diseases and have other health-enhancing effects. Moreover, they are now often being investigated because of their anti-cancer properties/potentials. Understanding the effects of various natural products on cancer cells may enhance their usage as anti-proliferative agents which may be beneficial for many health problems. In this manuscript, we discuss and demonstrate how certain nutraceuticals may enhance other anti-cancer drugs to suppress proliferation of cancer cells.

Regulation of GSK-3 activity by curcumin, berberine and resveratrol: Potential effects on multiple diseases.

Natural products or nutraceuticals promote anti-aging, anti-cancer and other health-enhancing effects. A key target of the effects of natural products may be the regulation of the PI3K/PTEN/Akt/mTORC1/GSK-3 pathway. This review will focus on the effects of curcumin (CUR), berberine (BBR) and resveratrol (RES), on the PI3K/PTEN/Akt/mTORC1/GSK-3 pathway, with a special focus on GSK-3. These natural products may regulate the pathway by multiple mechanisms including: reactive oxygen species (ROS), cytokine receptors, mirco-RNAs (miRs) and many others. CUR is present the root of turmeric (Curcuma longa). CUR is used in the treatment of many disorders, especially in those involving inflammatory processes which may contribute to abnormal proliferation and promote cancer growth. BBR is also isolated from various plants (Berberis coptis and others) and is used in traditional medicine to treat multiple diseases/conditions including: diabetes, hyperlipidemia, cancer and bacterial infections. RES is present in red grapes, other fruits and berries such as blueberries and raspberries. RES may have some anti-diabetic and anti-cancer effects. Understanding the effects of these natural products on the PI3K/PTEN/Akt/mTORC1/GSK-3 pathway may enhance their usage as anti-proliferative agent which may be beneficial for many health problems.

Effects of resveratrol, curcumin, berberine and other nutraceuticals on aging, cancer development, cancer stem cells and microRNAs.

Natural products or nutraceuticals have been shown to elicit anti-aging, anti-cancer and other health-enhancing effects. A key target of the effects of natural products may be the regulation of microRNA (miR) expression which results in cell death or prevents aging, diabetes, cardiovascular and other diseases. This review will focus on a few natural products, especially on resveratrol (RES), curcumin (CUR) and berberine (BBR). RES is obtained from the skins of grapes and other fruits and berries. RES may extend human lifespan by activating the sirtuins and SIRT1 molecules. CUR is isolated from the root of turmeric (Curcuma longa). CUR is currently used in the treatment of many disorders, especially in those involving an inflammatory process. CUR and modified derivatives have been shown to have potent anti-cancer effects, especially on cancer stem cells (CSC). BBR is also isolated from various plants (e.g., Coptis chinensis) and has been used for centuries in traditional medicine to treat diseases such as adult- onset diabetes. Understanding the benefits of these and other nutraceuticals may result in approaches to improve human health.

Roles of TP53 in determining therapeutic sensitivity, growth, cellular senescence, invasion and metastasis.

TP53 is a critical tumor suppressor gene that regulates cell cycle progression, apoptosis, cellular senescence and many other properties critical for control of normal cellular growth and death. Due to the pleiotropic effects that TP53 has on gene expression and cellular physiology, mutations at this tumor suppressor gene result in diverse physiological effects. T53 mutations are frequently detected in numerous cancers. The expression of TP53 can be induced by various agents used to treat cancer patients such as chemotherapeutic drugs and ionizing radiation. Radiation will induce Ataxia telangiectasia mutated (ATM) and other kinases that results in the phosphorylation and activation of TP53. TP53 is also negatively regulated by other mechanisms, such as ubiquitination by ligases such as MDM2. While TP53 has been documented to control the expression of many "classical" genes (e.g., p21Cip-1, PUMA, Bax) by transcriptional mechanisms for quite some time, more recently TP53 has been shown to regulate microRNA (miR) gene expression. Different miRs can promote oncogenesis (oncomiR) whereas others act to inhibit tumor progression (tumor suppressor miRs). Targeted therapies to stabilize TP53 have been developed by various approaches, MDM2/MDM4 inhibitors have been developed to stabilize TP53 in TP53-wild type (WT) tumors. In addition, small molecules have been isolated that will reactivate certain mutant TP53s. Both of these types of inhibitors are in clinical trials. Understanding the actions of TP53 may yield novel approaches to suppress cancer, aging and other health problems.