Post-translational modifications such as phosphorylation, methylation, ubiquitination, and acetylation are crucial regulatory modules at the heart of biological processes in the cell and are tightly regulated by a multitude of enzymes. Histones are the chief protein components of chromatin, acting as spools around which DNA winds. The balance of histone acetylation and deacetylation is a critical role in the regulation of gene expression. Histone acetylation induced by histone acetyl transferases (HATs) is associated with gene transcription, while histone hypoacetylation induced by histone deacetylase (HDAC) activity is associated with gene silencing. Unlike acetylation, histone lysine methylation can signal either activation or repression, depending on the site and degree (mono-, di-, or tri-) of methylation.
HDACs also regulate the acetylation status of a variety of other non-histone substrates, including key tumor suppressor proteins and oncogenes. Altered expression and mutations of genes that encode HDACs have been linked to tumor development since they both induce the aberrant transcription of key genes regulating important cellular functions such as cell proliferation, cell-cycle regulation and apoptosis. Thus, HDACs are among the most promising therapeutic targets for cancer treatment. HDAC inhibitors have been shown to change the expression pattern of genes involved in differentiation, cell cycle arrest, and apoptosis, and have demonstrated anti-cancer efficacy in clinical trials.
HDAC inhibitor-based therapies and haematological malignancy.
Histone deacetylases and cancer.
The biology of HDAC in cancer: the nuclear and epigenetic components.
Overlapping functions of Hdac1 and Hdac2 in cell cycle regulation and haematopoiesis.
Epigenetic therapy in lung cancer.
The role of histone deacetylases in prostate cancer.
Lipids, LXRs and prostate cancer: Are HDACs a new link?
Histone deacetylase inhibition: an important mechanism in the treatment of lymphoma.
HDAC inhibitor-based therapies: can we interpret the code?
Valproic acid, a commonly prescribed antiepileptic agent with histone deacetylase (HDAC) inhibitory activity, inhibits almost all class I and II histone deacetylase enzymes and causes significant dose-dependent accumulation of hyperacetylated histones. Valproic acid, being a HDAC inhibitor, induces differentiation, cell cycle arrest, and/or sensitizes cancer and leukemia cells to apoptosis and restores the apoptotic pathway. Both mitochondrial and death receptor pathways are involved in valproic acid-induced apoptosis. Most importantly, valproic acid induces differentiation of carcinoma cells or transformation of transformed hematopoietic progenitor cells and leukemic blasts from acute myeloid leukemia back to normal. Carcinoma cells can also be reverted to a normal phenotype.
Valproic acid sensitizes K562 erythroleukemia cells to TRAIL/Apo2L-induced apoptosis.
Angiogenesis (blood vessel growth) is critical for invasive tumor growth and metastasis. Valproic acid inhibits angiogenesis by a mechanism involving a decrease in eNOS expression preceded by HDAC inhibition. Endothelial dysfunction could be due to decreased eNOS expression. HDAC inhibition also inhibits angiogenesis through promoting a pericyte phenotype associated with stabilization/maturation of blood vessels. Valproic acid also inhibits invasion and migration of tumor cell through different mechanisms.
Valproic acid inhibits angiogenesis in vitro and in vivo.
Effects of the histone deacetylase inhibitor valproic acid on human pericytes in vitro.
Valproic acid inhibits prostate cancer cell migration by up-regulating E-cadherin expression.
Unfortunately, HDAC inhibitors are limited in their ability to induce apoptosis in cancer cells despite their ability to effectively inhibit deacetylase activity. Because HDAC inhibitors activate the major anti-apoptotic transcription factor NF-κB in cancer cells. NF-kB provides a critical mechanistic link between inflammation and cancer. NF-κB has been shown to be under the control of HDAC-mediated repression. The intricate involvement of histone acetyltransferases and histone deacetylases modulates both the NF-kB-signaling pathway and the transcriptional transactivation of NF-kB-dependent genes.
The ineffectiveness of HDAC inhibitors to induce apoptosis in cancer cells is associated with the ability of these molecules to stimulate NF-κB-dependent transcription and cell survival. Thus, we need to block NF-kB activity by using GSK-3 inhibitor lithium. GSK-3 (glycogen synthase kinase 3) promotes NF-kB induced gene transcription and enhances inflammation primarily by activating NF-kB activity in the nucleus. Thus, inhibition of GSK-3 results in inhibition of the NF-kB pathway and reduction of NF-kB-mediated transcription. Furthermore, GSK-3 inhibitor lithium modulates cancer cell growth, apoptosis, gene expression and cytokine production in many different types of cancer and leukemia. Lithium, the simplest drug in the modern pharmacopoeia, extends from its complex actions in cells to its therapeutic effects as an anti-cancer agent. Therefore, valproic acid and lithium are tremendously synergistic.
But there is a problem. Valproic acid, an excellent HDAC inhibitor, is a prescription drug. If valproic acid is not available, you can use ButterZym. ButterZym contains both valproic acid and parthenolide, the main extracts of sesquiterpene lactone isolated from medicinal herbs such as feverfew (Tanacetum parthenium). Parthenolide is another powerful HDAC inhibitor. Importantly, Parthenolide also blocks NF-kB activation. The following study shows that parthenolide powerfully synergises with valproic acid to induce cancer cell apoptosis.
Bioavailable Parthenolide is a specific Histone Deacetylase (HDAC) Inhibitor, Part 1
Bioavailable Parthenolide is a specific Histone Deacetylase (HDAC) Inhibitor, Part 2
The mTOR (mammalian target of rapamycin) is the hub of the PI3-K→Akt→mTOR pathway, which is one of the most commonly mutated pathways in cancer. The mTOR pathway is involved in cancer and leukemia cell growth. Blocking mTOR activity is a therapeutic priority. The following study shows that mTOR inhibitor powerfully synergises with HDAC inhibitor valproic acid and parthenolide to inhibit cancer cell growth, migration and invasion. Caffeine, quercetin and fisetin inhibit mTOR activity. Fisetin, a dietary flavonoid, is found in fruits and vegetables, such as strawberry, apple, persimmon, grape, onion and cucumber. Fisetin has been reported to inhibit cell cycle progression in colon cancer cells. It has also been shown to have antiproliferative effect on the prostate and breast cancer cells
Overcoming acquired resistance to anticancer therapy: focus on the PI3K/AKT/mTOR pathway.
Novel mTOR inhibitory activity of ciclopirox enhances parthenolide antileukemia activity.
Farnesylthiosalicylic acid blocks mammalian target of rapamycin signaling in breast cancer cells.
Inhibition of mTOR Signaling by Quercetin in Cancer Treatment and Prevention.
Inhibition of Akt/mTOR Signaling by the Dietary Flavonoid Fisetin.
The proteasome is an enzyme complex in the cell and plays a critical role in regulation of cell division in both normal as well as cancer cells. In cancer cells this homeostatic function is deregulated leading to the hyperactivation of the proteasomes. The ubiquitin-proteasome pathway is a major pathway for degradation of intracellular proteins. Loss of muscle mass in cancer patients, called cachexia, is also associated with enhanced protein degradation via the ubiquitin proteasome pathway.
Proteasome inhibitors block the activity of proteasomes and induce cancer cell death. Interference of proteasome inhibitors with the ubiquitin-proteasome pathway involved in protein turnover in the cell leads to the accumulation of proteins engaged in cell cycle progression, which ultimately put a halt to cancer cell division and induce apoptosis. Upregulation of many tumor suppressor proteins involved in cell cycle arrest are known to play a role in proteasome inhibitors induced cell cycle arrest in a variety of cancer cells. Moreover, the inhibition of the proteasome blocks the activation of NF-kB.
EGCG, the major polyphenolic compound found in green tea, is a powerful proteasome inhibitor at very low doses. The combination of proteasome inhibitor EGCG and HDAC inhibitor valproic acid appear to be the most potent to produce synergistic cytotoxicity in clinical trials. Interestingly, L-carnitine also works as a HDAC inhibitor in the cell and synergistically exerts anti-tumor activity with proteasome inhibitor. Unfortunarely, there isn’t enough EGCG produced in the world to make it useful as a natural treatment for all cancers. EGCG products in supplement form are worthless due to low-purity and (or) low-bioavailability. EGCG is poorly bioavailable orally and extremely unstable. Commercially available EGCG capsules are worthless because the EGCG concentrates in the intestines, and doesn’t enter the body effectively, which means that most of what you swallow goes directly into your gastrointestinal area and is expelled.
In addition, presently commercially available liquid green tea extracts contain low-purity EGCG. Other green tea polyphenols can antagonize the medicinal efficacy of EGCG, so it’s important to use a highly pure form of EGCG. In order to introduce the highest purity EGCG into the blood via absorption and maximize the activity in the body, EGCG-MAX can be used. EGCG-MAX is the one and only product in the entire world that has the highest purity and perfect bioavailability of EGCG enough to induce apoptosis of the cancer cells. EGCG-MAX is pure liquid 95% EGCG. This is the most concentrated form of liquid EGCG on the market (95%).
Targeting the ubiquitin-proteasome pathway: an emerging concept in cancer therapy.
Therapeutic targeting of cancer cell cycle using proteasome inhibitors.
Revisiting the role of EGCG-MAX (Pure Liquid 95% EGCG) in the treatment of all cancers and leukemias
Efficacious proteasome/HDAC inhibitor combination therapy for primary effusion lymphoma.
Our goal is to develop one unified synergistic treatment protocol for the treatment of a variety of cancers, including cancers of prostate, breast, colon, stomach, pancreas, lung, liver, and brain, and acute and chronic leukemias. The combined synergistic use of HDAC inhibitor, GSK-3 inhibitor, mTOR inhibitor and proteasome inhibitor exert powerful anti-tumor activity and could have a profound effect on the promotion of cancer cell death. The good news is that you can use all of these four powerful inhibitors from the single product CellZym. CellZym is a unique all-in-one anticancer product. CellZym has been clinically designed to stop, reverse and possibly even cure cancer.
