Meet the BCL-2 Family

Video originally posted by Genetech. From their site:

“Apoptosis is often evaded in cancer cells via overexpression of anti-apoptotic Bcl-2 family proteins and dysregulation of pro-apoptotic proteins. The Bcl-2 family members bind pro-apoptotic proteins to prevent apoptosis mediated by the intrinsic apoptotic pathway.

Bcl-2 is overexpressed in several hematologic malignancies, including non-Hodgkin’s lymphoma. Preclinical studies demonstrate that Bcl-2 acts as a key regulator of the intrinsic apoptotic signaling pathway by sequestering and neutralizing pro-apoptotic molecules, such as Bax.7 Thus, the anti-apoptotic protein promotes B-cell survival by inhibiting apoptosis, which may result in oncogenic chemotherapy resistance in hematologic malignancies”.

 

This cool image is also Genetech’s.

apoptosis-hr-lg

Impact of bone marrow stromal cells on Bcl-2 family members in chronic lymphocytic leukemia

The BCL-2 Family Reunion

Bodyguards and assassins: Bcl-2 family proteins and apoptosis control in chronic lymphocytic leukaemia

A new face of BCL-2 inhibition in CLL – inhibiting BCL-2 can promote cell death by perturbing calcium signaling!

“Zhong et al focus on a different facet of BCL-2, the BH4 domain that is involved in the interaction with IP3R. Using an oligopeptide derived from a site on IP3R found to be involved in binding BCL-2, the authors had previously demonstrated the ability to disrupt the BCL-2:IP3R complex and alter calcium signaling. This current report is noteworthy in two ways: first, it reports a modification of the peptide that increased cytoplasmic calcium concentrations; and second, it finds that CLL cells are selectively susceptible to death induced by the calcium signaling…”

Shikonin – another natural mitocan

“Shikonin, a natural naphthoquinone, was used in traditional Chinese medicine for the treatment of different inflammatory diseases and recent studies revealed the anticancer activities of shikonin. We found that shikonin has strong cytotoxic effects on 15 cancer cell lines, including multidrug-resistant cell lines. Transcriptome-wide mRNA expression studies showed that shikonin induced genetic pathways regulating cell cycle, mitochondrial function, levels of reactive oxygen species, and cytoskeletal formation. Taking advantage of the inherent fluorescence of shikonin, we analyzed its uptake and distribution in live cells with high spatial and temporal resolution using flow cytometry and confocal microscopy. Shikonin was specifically accumulated in the mitochondria, and this accumulation was associated with a shikonin-dependent deregulation of cellular Ca2+ and ROS levels. This deregulation led to a breakdown of the mitochondrial membrane potential, dysfunction of microtubules, cell-cycle arrest, and ultimately induction of apoptosis. Seeing as both the metabolism and the structure of mitochondria show marked differences between cancer cells and normal cells, shikonin is a promising candidate for the next generation of chemotherapy”.

Shikonin Directly Targets Mitochondria and Causes Mitochondrial Dysfunction in Cancer Cells

Shikonin circumvents cancer drug resistance by induction of a necroptotic death

shikonin

Metabolic Targets in the Crosshairs

“Mitochondria are emerging as idealized targets for anti-cancer drugs. One reason for this is that although these organelles are inherent to all cells, drugs are being developed that selectively target the mitochondria of malignant cells without adversely affecting those of normal cells. Such anticancer drugs destabilize cancer cell mitochondria and these compounds are referred to as mitocans, classified into several groups according to their mode of action and the location or nature of their specific drug targets. Many mitocans selectively interfere with the bioenergetic functions of cancer cell mitochondria, causing major disruptions often associated with ensuing overloads in ROS production leading to the induction of the intrinsic apoptotic pathway. This in-depth review describes the bases for the bioenergetic differences found between normal and cancer cell mitochondria, focusing on those essential changes occurring during malignancy that clinically may provide the most effective targets for mitocan development. A common theme emerging is that mitochondrially mediated ROS activation as a trigger for apoptosis offers a powerful basis for cancer therapy. Continued research in this area is likely to identify increasing numbers of novel agents that should prove highly effective against a variety of cancers with preferential toxicity towards malignant tissue, circumventing tumor resistance to the other more established therapeutic anti-cancer approaches”. Follow the links:

Bioenergetic pathways in tumor mitochondria as targets for cancer therapy and the importance of the ROS-induced apoptotic trigger

Choosing between glycolysis and oxidative phosphorylation: A tumor’s dilemma?

Targeting Cell Metabolism In Chronic Lymphocytic Leukaemia (CLL); A Viable Therapeutic Approach?

Stalling the Engine of Resistance: Targeting Cancer Metabolism to Overcome Therapeutic Resistance

Is Cancer a Metabolic Disease?

Cancer as a Metabolic Disease

Targeting mitochondria for cancer therapy

Mitochondrial permeability transition pore as a selective target for anti-cancer therapy

Mitochondrial uncoupling and the reprograming of intermediary metabolism in leukemia cells

Mitocans as Novel Agents for Anticancer Therapy: An Overview

Apoptosis: from biology to therapeutic targeting

 

Metabolic targets in the crosshairs

Metabolic targets in the cross hairs

 

 

 

 

DCA – turning on OxPhos

“Inhibition of mitochondrial pyruvate dehydrogenase kinase (PDK) by dichloroacetate may be exploited to reverse the abnormal metabolism of cancer cells from glycolysis to glucose oxidation. As PDK negatively regulates pyruvate dehydrogenase, dichloroacetate indirectly stimulates the pyruvate to acetyl-CoA conversion. Dichloroacetate has been shown to downregulate the aberrantly high mitochondrial membrane potential of cancer cells, increase mitochondrial ROS generation and activate K+ channels in malignant, but not in normal cells143. Dichloroacetate also upregulated the expression of the K+ channel Kv1.5, which is often underexpressed by tumour cells, through the transcription factor nuclear factor of activated T cells (NFAT1). Dichloroacetatenormalized mitochondrial functions were accompanied by reduced proliferation, increased apoptosis and suppressed tumour growth without apparent toxicity, suggesting that the mitochondria–NFAT–Kv axis and PDK represent promising anticancer drug targets”.

Sodium dichloroacetate exhibits anti-leukemic activity in B-chronic lymphocytic leukemia (B-CLL) and synergizes with the p53 activator Nutlin-3

The anti-leukemic activity of sodium dichloroacetate in p53mutated/null cells is mediated by a p53-independent ILF3/p21 pathway

Targeting mitochondria for cancer therapy

738px-Dichloroacetic-acid-2D-skeletal

Sodium dichloroacetate exhibits anti-leukemic activity in B-chronic lymphocytic leukemia (B-CLL) and synergizes with the p53 activator Nutlin-3

Sodium dichloroacetate selectively targets cells with defects in the mitochondrial ETC

Combination of Sulindac and Dichloroacetate Kills Cancer Cells via Oxidative Damage

CLL, BH3 Mimetics, and Apoptosis Round II – Meet Hyperforin

Time for another natural anti-cancer compound that works in a manner similar to gossypol; it up-regulates the pro-apoptotic BH3 protein Noxa. It comes from St. John’s Wort.

“We previously reported that hyperforin, a phloroglucinol purified from Hypericum perforatum, induces the mitochondrial pathway of caspase-dependent apoptosis in chronic lymphocytic leukemia (CLL) cells ex vivo, and that this effect is associated with upregulation of Noxa, a BH3-only protein of the Bcl-2 family. Here, we investigated the role of this upregulation in the pro-apoptotic activity of hyperforin in the cells of CLL patients and MEC-1 cell line. We found that the increase in Noxa expression is a time- and concentration-dependent effect of hyperforin occurring without change in Noxa mRNA levels. A post-translational regulation is suggested by the capacity of hyperforin to inhibit proteasome activity in CLL cells. Noxa silencing by siRNA reduces partially hyperforin-elicited apoptosis. Furthermore, treatment with hyperforin, which has no effect on the expression of the prosurvival protein Mcl-1, induces the interaction of Noxa with Mcl-1 and the dissociation of Mcl-1/Bak complex, revealing that upregulated Noxa displaces the proapoptotic protein Bak from Mcl-1. This effect is accompanied with Bak activation, known to allow the release of apoptogenic factors from mitochondria. Our data indicate that Noxa upregulation is one of the mechanisms by which hyperforin triggers CLL cell apoptosis. They also favor that new agents capable of mimicking specifically the BH3-only protein Noxa should be developed for apoptosis-based therapeutic strategy in CLL”.

 

Hyperforin structure

Hyperforin structure

Hyperforin induces apoptosis of chronic lymphocytic leukemia cells through upregulation of the BH3-only protein Noxa

Noxa upregulation is associated with apoptosis of chronic lymphocytic leukemia cells induced by hyperforin but not flavopiridol

Green Tea/Curcumin – a one-two punch for CLL

Once again we have natural compounds that have strong anti-cancer activity and effect multiple pathways. There’s quite a bit of overlap between these two, but also some antagonism as well, so if you decide to supplement these pay attention to the required dosing schedule.

EGCG curcumin

Curcumin Inhibits Pro-survival Pathways in CLL B-cells and has the Potential to Overcome Stromal Protection of CLL B-cells in Combination with EGCG

Turmeric and green tea: a recipe for B-Chronic Lymphocytic Leukemia

VEGF receptor phosphorylation status and apoptosis is modulated by a green tea component, epigallocatechin-3-gallate (EGCG), in B-cell chronic lymphocytic leukemia

Phase 2 Trial of Daily, Oral Polyphenon E in Patients with Asymptomatic, Rai Stage 0-II Chronic Lymphocytic Leukemia(CLL)