Effects of permeability transition inhibition and decrease in cytochrome c content on doxorubicin toxicity in K562 cells

Abstract

As mitochondria play a key role in the commitment to cell death, we have investigated the mitochondrial consequences of resistance to doxorubicin (DOX) in K562 cells. We found that the permeability transition pore (PTP) inhibitor cyclosporine A (CsA) failed to inhibit PTP opening in the resistant clone. Moreover, the Ca 2 þ loading capacity in the resistant clone was identical to that observed in the parent cells in the presence of CsA, suggesting that the PTP was already inhibited in a CsAlike manner in the resistant cells. In agreement with this proposal, the mitochondrial target of CsA cyclophilin D (CyD) decreased by half in the resistant cells. The levels of adenine nucleotide translocator, voltage anion-dependent channel, Bax, Bcl-2, Bcl-x L , AIF and Smac/Diablo, were similar in both cell lines, whereas cytochrome c content was divided by three in the resistant cells. Since P-glycoprotein inhibition did not restore DOX toxicity in the resistant cells, while DOX-induced cell death in the parent cells was prevented by either PTP inhibition or siRNA-induced decrease in cytochrome c content, we conclude that the inhibition of PTP opening and the decrease in cytochrome c content participate in the mechanism that makes K562 cells resistant to DOX.

Diallyl disulfide causes caspase-dependent apoptosis in human cancer cells through a Bax-triggered mitochondrial pathway

“…Obviously, these changes may be directly related to regulation of mitochondrion membrane permeabilization. Impaired mitochondrion membrane permeabilization may lead to invalidation of the apoptotic response found in cancer [20,21]. Currently, more than 20 mitochondrion-targeted compounds have been reported to induce apoptosis selectively in malignant cell lines, and some of these are already being used in phase II/III clinical trials or are being validated in vitro in preclinical settings [22,23].…”

Restoration of CREB function is linked to completion and stabilization of adaptive cardiac hypertrophy in response to exercise

“…Our laboratory has previously published work on the CREB phosphorylation and bcl-2 gene expression in hypertrophic cardiomyopathy (HCM) transgenic mice and nontransgenic control animals, both sedentary and voluntarily exercising on an exercise wheel (28). Tissue from the same samples used to obtain the CREB and bcl-2 data in our laboratory's previous paper (28) was reanalyzed by Western blot to assess expression of PGC-1, Nrf-1, and cytochrome c, as well as two markers of mitochondrial content, VDAC1 (8,38) and COX IV (18,25,52).…”

“…Additional antisera, obtained from other sources, included mouse monoclonal anti-bcl-2 (BD Transduction Laboratories), rabbit polyclonal antiactive caspase 3 (Biomol), ␤-actin (mouse monoclonal; Sigma Chemical, St. Louis, MO), anti-PGC-1 antibody (rabbit polyclonal; Santa Cruz Biotech, Santa Cruz, CA), anti-cytochrome c antibody (mouse monoclonal; BD Pharmingen), and anti-pyruvate dehydrogenase E1␣ subunit (PDH-E1␣) antibody (mouse monoclonal; MitoSciences, Eugene, OR). Antisera against the voltage-dependent anion channel (VDAC1, or Porin) (8,38) and cytochrome oxidase IV (COX IV) (18,25,52) were obtained from Abcam (Cambridge, MA). These antisera have been used previously as markers of mitochondrial content as their contents parallel changes in mitochondrial density (8,18,25,38,52).…”

“…Antisera against the voltage-dependent anion channel (VDAC1, or Porin) (8,38) and cytochrome oxidase IV (COX IV) (18,25,52) were obtained from Abcam (Cambridge, MA). These antisera have been used previously as markers of mitochondrial content as their contents parallel changes in mitochondrial density (8,18,25,38,52). The anti-nuclear respiratory factor-1 (Nrf-1) rabbit polyclonal antibody was the generous gift of Dr. Richard Scarpulla, Northwestern University.…”

Cytoprotective potential of anti-ischemic drugs against chemotherapy-induced cardiotoxicity in H9c2 myoblast cell line

“…Interestingly, the mitochondrial shift towards a more oxidized state took place parallel with significant mitochondrial depolarization that occurred concurrently with increased mitochondrial Ca 2+ levels (26). It has been well established that the increase in Ca 2+ levels and drop in mitochondrial membrane potential are associated with the production of ROS and that both steps occur prior to the induction of mitochondrial permeability transition and subsequent cell death (27). We have shown that by blocking the calcium channels of H9c2 cells using diltiazem one can significantly reduce the influx of extra-cellular Ca 2+ , which minimizes the detrimental effects of doxorubicin.…”