Cholesterol level determines viability and mitogenicity, but it does not affect sodium butyrate-dependent sensitization of Colo 205 cells to TNF-α-induced apoptosis.

Transient treatment of human adenocarcinoma COLO 205 cells with lipit raft (LR) modulators (MßCD, NY, IMP) was followed by the challenge with metabolic inhibitors and selected anti-cancer drugs. To overturn cholesterol chelation, the MßCD, NY treatment was followed by cholesterol conjugates (CHOL-MßCD or CHOL-PEG). The TNF-α- and P(Ser473)-PKB/Akt1/2-mediated effects initiated at LR were evaluated with regard to cell viability and mitogenicity. Cholesterol chelators reversibly reduced cell survival, whereas some of the tested compounds had weak effects (CIS, CLA), stimulated (EGCG) or reduced (NaB) cell survival. Cellular localizations of LR-associated molecules (ceramides, Gαi-2 heterotrimeric protein, and TNF-R1) in different cellular compartments including the plasma membrane were observed in the respective photographs from TEM and SEM. Evidence from SEM also showed that TNF-R1 is clustered on the surface of COLO 205 cells without presence of cognate ligand but clustering is promoted by TNF-α, while it vanished after IMP treatment. COLO 205 cells remained immune to TNF-α-induced apoptosis unless NaB was added, in which case NaB-induced cell death was further potentiated by TNF-α. Combined NaB and TNF-α treatment was associated with marked changes in the expression of pro- and antiapoptotic proteins. In this study, we demonstrated that initial excess of prosurvival signals could be diminished by cholesterol chelators, whereas LR-independent cell survival could be targeted by NaB. Apparently, lipid rafts do not participate in NaB-dependent cell death.

Bisindolylmaleimides in anti-cancer therapy - more than PKC inhibitors.

Bisindolylmaleimide derivatives were originally described as protein kinase C inhibitors. However, several studies have shown that bisindolylmaleimides target several other signaling molecules. The review presents bisindolylmaleimide-mediated PKC-dependent and PKC-independent biological effects, such as reversal of MDR and modulation of Wnt signaling through GSK-3b and b-catenin. Importantly, the potent proapoptotic properties of bisindolylmaleimides are also described. Bis-IX appears as the most efficient activator of intrinsic apoptotic pathway and additionally, facilitates extrinsic apoptosis. Presented molecular mechanisms indicate that bisindolylmaleimides could be useful agents in anticancer therapy. They repress uncontrolled proliferation and restore the sensitivity to chemotherapy which allows eradication of cancer cells.

Crossroads of cytokine signaling--the chase to stop muscle cachexia.

There is no universal approach to stop muscle cachexia in a number of life-threatening diseases. Accordingly, it is uncertain why the body mass is so critical to keep alive patients with cancer, congestive heart failure (CHF), AIDS or sepsis. At present, it is widely believed that excess muscle wasting diminishes lean body mass to the risky level accompanied by anorexia, anemia, lipolysis, acute phase response and insulin resistance. If missed and/or untreated muscle cachexia inevitably leads to death due to cardiac and respiratory failure (almost one-third of all cancer deaths). This complex metabolic disorder is suited by the elevated levels of inflammatory cytokines (TNF-alpha, IFN-gamma, IL-1-beta, IL-6, IL-2) and low levels of anti-inflammatory/ other cytokines (IL-15, leptin). Concurrently, tissue sensitivity to insulin is considerably reduced. Recent findings indicate that entirely few muscle-specific genes (i.e. MyoD and myosin heavy chain, MyHC) and their products must be targeted to initiate muscle wasting. Muscle atrophy occurs at different levels, starting from repressed gene expression and ended with accelerated protein degradation. Muscle growth (myogenesis) is severely compromised and disruption of sarcomere architecture heralds the proteolysis of contractile apparatus. This review aims to synthesize our present knowledge of intracellular mechanisms and molecular regulation of muscle cachexia with respect to cytokine signaling.