Calphostin C

790.8

790.22615588

Red to brown powder

29209010

log Kow = 7.65

DMF /dimethylformamide/ 1 mg/mL; DMSO /dimethylsulfoxide/ 1 mg/mL; ethanol 1 mg/mL|In water, 7.48X10-7 mg/L at 25 °C (est)

When stored at -20 °C and protected from light, calphostin C should have a minimum shelf-life of two years.

pKa1 = 5.46; pKa2 = 6.52; pKa3 = 9.41 (phenols) (est)

Requires light for activation|Hydroxyl radical reaction rate constant = 3.19X10-12 cu cm/molec-sec at 25 °C (est)

SRP: At the time of review, criteria for land treatment or burial (sanitary landfill) disposal practices are subject to significant revision. Prior to implementing land disposal of waste residue (including waste sludge), consult with environmental regulatory agencies for guidance on acceptable disposal practices.

Wear appropriate chemical resistant gloves, safety goggles and other protective clothing to prevent contact with eyes and skin. Laboratory should be equipped with a safety shower and eye wash station. Avoid prolonged or repeated exposure. Do not breathe dust. Do not get in eyes, on skin or on clothing. Wash thoroughly after handling.

Wear appropriate protective clothing. Cover spillage with suitable absorbent material. Using non-spark tools, sweep up material and place in an appropriate container. Decontaminate spill site with with 10% caustic solution and ventilate area until after disposal is complete. Hold all material for appropriate disposal ....

SRP: The scientific literature for the use of contact lenses in industry is conflicting. The benefit or detrimental effects of wearing contact lenses depend not only upon the substance, but also on factors including the form of the substance, characteristics and duration of the exposure, the uses of other eye protection equipment, and the hygiene of the lenses. However, there may be individual substances whose irritating or corrosive properties are such that the wearing of contact lenses would be harmful to the eye. In those specific cases, contact lenses should not be worn. In any event, the usual eye protection equipment should be worn even when contact lenses are in place.|Due to the nature of this material. It must only be handled by suitably qualified experienced scientists in appropriately equipped and authorized facilities.|Use in a chemical fume hood, with air supplied by an independent system. Avoid inhalation, contact with eyes, skin and clothing. Avoid prolonged or repeated exposure.|SRP: Local exhaust ventilation should be applied wherever there is an incidence of point source emissions or dispersion of regulated contaminants in the work area. Ventilation control of the contaminant as close to its point of generation is both the most economical and safest method to minimize personnel exposure to airborne contaminants.|For more Preventive Measures (Complete) data for CALPHOSTIN C (6 total), please visit the HSDB record page.

Exposure may cause irritation to eyes, mucous membranes, upper respiratory tract and skin.

/EXPTL THER/: The development of novel therapeutic agents to modulate programmed cell death independent of genetic background or malignant potential is a primary goal of modern cancer therapy. In this report, the light activation- and concentration-dependent cytotoxicity of calphostin C, a photoactivatable perylenequinone, is carefully evaluated using a series of nine well-characterized human and rodent prostate cancer cell lines representing the spectrum of disease progression (e.g., variations in metastatic ability, ploidy, and tumor suppressor gene status). Treatment of these cancer cell lines with nanomolar concentrations of calphostin C in combination with increasing amounts of light exposure established a relationship between light and dose dependence of calphostin C cytotoxicity. The induction of apoptosis is rapid, as evidenced by the fact that immediately after treatment, cells exposed to calphostin C with light activation exhibit both morphological and biochemical changes consistent with apoptosis (cellular and nuclear shrinkage and chromatin condensation). For example, 78% of cells treated with 100 nM calphostin C in combination with 2 hr of light activation underwent apoptosis within 24 h of treatment. DNA ladder formation could be detected within 12 hr of treatment. In the absence of light activation, treatment with calphostin C at all concentrations tested had no acute or durable cytotoxic effects in any of the cell lines. ... Calphostin C cytotoxicity is strictly light dependent. Furthermore, its efficacy is independent of the genetic background, p53 status, or in vivo malignant potential of a cell, making it a suitable candidate for the treatment of heterogeneous tumor cell populations.|/EXPTL THER/: Calphostin C, a highly specific protein kinase C inhibitor, induces apoptosis in the presence of visible light. ... The human bladder cancer cell lines RT4, UM-UC-3, and 5637 were chosen on the basis of their p53, pRb and 9p21 deletion status. Using standard tissue culture techniques, the cytotoxicity of 10 to 100 nM calphostin C in combination with increasing exposures of visible light was examined. Controls consisted of cells treated with calphostin C without visible light and cells exposed to visible light without calphostin C treatment. Cell viability was determined by MTT assay. ... In the absence of light, calphostin C did not demonstrate a cytotoxic effect on any of the cell lines tested. Increasing the duration of light exposure resulted in a concomitant decrease in cell viability. Significant cell death was seen with calphostin C concentrations as low as 10 nM. These studies also demonstrated that calphostin C induced apoptosis by a mechanism independent of p53 and pRb status and the presence or absence of 9p21 deletions. ... Further development of calphostin C as a photosensitizer for photodynamic therapy of superficial bladder cancer may be warranted.|/EXPTL THER/: ... To assess the effectiveness of /calphostin C/ this agent in killing doxorubicin- or paclitaxel-resistant breast tumor cells and to explore its mode of action, MCF-7 cells were exposed to increasing concentrations of either doxorubicin or paclitaxel until maximum resistance was obtained. This resulted in the creation of isogenic drug-resistant MCF-7TAX and MCF-7DOX cell lines, which were approximately 50- and 65-fold resistant to paclitaxel and doxorubicin, respectively. Interestingly, calphostin C was able to kill MCF-7TAX cells as efficiently as wildtype MCF-7 cells (IC50s were 9.2 and 13.2 nM, respectively), while MCF-7DOX cells required a 5-fold higher concentration of calphostin C to achieve the same killing (IC50 = 64.2 nM). ... Consequently, calphostin C may prove useful clinically to combat tumor growth in breast cancer patients whose tumors have become unresponsive to anthracyclines or taxanes, particularly in association with photodynamic therapy.|/EXPL THER/: Recent studies have suggested that the proliferation of malignant gliomas may result from activation of protein kinase C (PKC)-mediated pathways; conversely, inhibition of PKC may provide a strategy for blocking tumor growth. In the current studies, /the investigators/examined the effect of a novel PKC inhibitor, calphostin C, which is a selective, highly potent, photo-activatable inhibitor of the PKC regulatory domain, on the proliferation and viability of three established and three low-passage malignant glioma cell lines, four low-passage low-grade glioma cell lines, and in adult human and neonatal rat non-neoplastic astrocyte cell lines in vitro. Under light-treated conditions, calphostin C consistently inhibited cell proliferation in each of the tumor cell lines and in the neonatal rat astrocyte cell line with a 50% effective concentration of 30 to 50 ng/ml (40 to 60 nm), which was comparable to the previously reported median inhibitory concentration (IC50) for PKC inhibition by calphostin C. Complete elimination of proliferation was achieved at concentrations of 50 to 100 ng/ml (60 to 125 nM). Cell viability decreased sharply with calphostin C concentrations of 100 to 300 ng/ml (125 to 380 nM). In contrast, under light-shielded conditions, calphostin C had a comparatively modest effect on cell proliferation and viability, with a median effective concentration of approximately 300 ng/ml. No significant inhibition of proliferation was noted in the non-neoplastic adult astrocyte cell line under either light-treated or light-shielded conditions.

Chemical substances, produced by microorganisms, inhibiting or preventing the proliferation of neoplasms. (See all compounds classified as Antibiotics, Antineoplastic.)|Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction. (See all compounds classified as Enzyme Inhibitors.)

Calphostin is a perylenequinone metabolite of the fungus Cladosporium cladosporioides.

Calphostin C is a potent inhibitor of protein kinase C (IC50 = 0.05 mM). Calphostin C also inhibits protein kinase A at much higher concentrations (IC50>50mM).|Calphostin-c inhibits protein kinase C (PKC) isoenzymes by covalent modification of the lipid binding regulatory domain. Exposure of cells to calphostin-c elicits PKC independent effects including disruption of intracellular transport, growth inhibition, and stimulation of apoptosis suggesting actions at additional targets. Phospholipase D (PLD) enzymes are targets for activation by PKC /so/ ... the PKC isoenzyme selectivity for activation of two mammalian PLD enzymes, PLD1 and PLD2, by PKC /were investigated/. ..../Examining/ the sensitivity of this process to widely used PKC inhibitors /resulted in/ the surprising finding that calphostin-c is a potent direct inhibitor of PLD1 and PLD2. In vitro, calphostin-c inhibits activity of both PLD1 and PLD2 with an IC(50) of approximately 100 nM. Inhibition is not overcome by protein and lipid activators of these enzymes and does not involve blockade of phosphatidylinositol 4,5-bisphosphate-dependent PLD binding to substrate containing liposomes. Studies using a series of deletion and point mutants of the enzymes suggest that calphostin-c targets the PLD catalytic domain. Inhibition of PLD by calphostin-c in vitro involves stable and apparently irreversible modification of the enzyme. Activity of both PLD1 and PLD2 can be inhibited by calphostin-c treatment of intact cells in a manner that is independent of upstream actions of PKC. Our results suggest that inhibition of PLD1 and PLD2 may explain some of the PKC-independent effects of calphostin-c observed when the compound is applied to intact cells.|Vascular smooth muscle cells (VSMCs) play a major role in the development of atherosclerotic and restenotic lesions. The apoptotic process has been implicated in the development of this pathology. ... This study ... characterized the induction of apoptosis by calphostin C (CC), a protein kinase C (PKC) inhibitor, in primary human coronary artery smooth muscle cells in the presence and absence of insulin-like growth factor-I (IGF-I). Additionally, ... signal transduction pathways important for IGF-I mediated protection /were investigated/. Calphostin C induced apoptosis, as measured by terminal deoxy-UTP nick-end labeling (TUNEL), in a time- and dose-dependent manner, approaching 20% within 6 hr of 50 nM calphostin C treatment. The amount of apoptosis increased to 44.58+/-8.08%, 47.54+/-1.66% and 78.1+/-11.9% after 8, 10 and 12 hr of treatment, respectively (p<0.01 vs. control). IGF-I offered significant protection (p<0.05) at 8 and 10 hr of treatment (60.6% and 52.5% protection, respectively). DNA ELISA confirmed the apoptotic effect of calphostin C and the protective effect of IGF-I. After 6 hr of calphostin C treatment, DNA ELISA revealed 11.20+/-1.53 fold greater apoptosis as compared to baseline values. IGF-I treatment offered a level of protection of 46.6% as measured by DNA ELISA (p=0.06). Apoptosis was further qualitatively confirmed by time-lapse video microscopy and scanning electron microscopy. Interestingly, inhibitors of phosphatidylinositol-3-kinase (PI-3-K), p38 and extracellular regulated kinase (ERK) activation significantly (p<0.05 vs. calphostin C only treatment) increased apoptosis when used in conjunction with calphostin C. Inhibitors of phospatidylinositol-3-kinase and ERK activation reversed IGF-I protection. However, the p38 inhibitor SB203580 failed to reverse IGF-I protection. ...|...Tissue transglutaminase (tTG) has been recognized as a mediator of apoptosis in various experimental models. ... Activation of tTG in cells exposed to the apoptotic inducer calphostin C triggers the crosslinking of dual leucine zipper-bearing kinase (DLK), a proapoptotic kinase acting as an essential component of the c-Jun amino-terminal kinase (JNK) signaling pathway. As a consequence of this observation, ... experiments to investigate the functional relevance of DLK oligomerization in tTG-mediated apoptosis /were undertaken/. /The/ results indicate that, in cells undergoing calphostin C-induced apoptosis, tTG-dependent DLK oligomerization occurs early in the apoptotic response. Both immunocomplex kinase assays and immunoblotting with phosphospecific antibodies revealed that oligomer formation by tTG-mediated crosslinking reactions significantly enhanced the kinase activity of DLK and its ability to activate the JNK pathway. Moreover, functional studies demonstrate that tTG-mediated oligomerization of wild-type DLK sensitizes cells to calphostin C-induced apoptosis, while crosslinking of a kinase-inactive variant of DLK does not. Collectively, these data strongly suggest that tTG facilitates apoptosis, at least partly, by oligomerization and activation of the proapoptotic kinase DLK.|For more Mechanism of Action (Complete) data for CALPHOSTIN C (11 total), please visit the HSDB record page.

/OTHER TOXICITY INFORMATION/ Potent, selective and photo-dependent inhibitor of protein kinase C that targets the regulatory domain (IC50 = 50 nM). Displays > 1000-fold selectivity over other protein kinases such as cAMP-dependent protein kinase and tyrosine-specific protein kinase. Inhibits cell proliferation of malignant glioma cells in light-treated conditions in vitro (IC50 ~ 40-60 nM).

calphostin C

Calphostin C from Cladosporium cladosporioides|Stock solutions of calphostin C are typically made in DMSO up to 1 mg per mL. Solutions should be prepared fresh.