Tumor apoptosis induced by ruthenium(II)‐ketoconazole is enhanced in nonsusceptible carcinoma by monoclonal antibody to EGF receptor

Abstract

KTZ, originally developed as an antifungal agent, exhibits concentration-dependent inhibitory and potentiating effects on microtubule drugs like vinblastine at concentration ranges near plasma levels of KTZ attained in human subjects. 1 KTZ is a cytochrome P-450 inhibitor that inhibits adrenal steroidogenesis 2 and shows antiglucocorticoid activity. 3 KTZ synergizes with docetaxel in the treatment of hormone-dependent cancer. 4 This finding was preceded by a report that KTZ exerts a cytostatic effect on human prostate cancer cell lines resistant to microtubule-active drugs, like vinblastine and paclitaxel, and enhances the response to these drugs. 5 Among the mechanisms involved in its anticarcinoma action, it has been reported that KTZ induces apoptosis through a p53-dependent pathway 6 and induces G 0 /G 1 arrest 7 in colorectal and hepatocellular carcinoma lines. Another azole derivative which shows potentially useful antitumor activity is CTZ, recognized as a calmodulin antagonist and inhibitor of glycolysis and known to be the primary energy source in most cancer cells. 8 CTZ induced significant reduction in glycolysis and ATP levels, which led to tumor cell destruction after 3 hr. 8 There is a need to enhance the efficacy of potentially useful anticancer agents like KTZ and CTZ and to develop new compounds capable of activity against tumor cells refractory to apoptosis since the latter property usually correlates with drug resistance.Since genetic alterations involving p53 mutation frequently correlate with decreased response to cancer chemotherapy, 9,10 we investigated whether Ru(II) complexes with CTZ or KTZ 11-13 are more effective than the parent compounds at promoting cell death in tumors with such genetic changes. The reason for this study with Ru(II)-azole complexes is to expand the range of potentially useful antitumor Ru agents since an Ru(III) complex like NAMI-A, 14 -16 which may require reduction of its Ru(III) moiety to act, has shown promising anticancer activity in initial clinical trials. 15 The effects of NAMI-A are often compared to the widely known anticancer drug cisplatin, similarly based on another transition metal. 17 Interestingly, most of the Ru complexes tested to date, including NAMI-A, have not been strikingly more cytotoxic than cisplatin, the most appropriate reference control. 17 While the effect of NAMI-A on metastasis inhibition was previously described in several models, 14,15 its mechanism of action was demonstrated only recently. In vitro studies showed that 100 M NAMI-A, active on lung tumor metastases, 14 induced apoptosis of a transformed ECV304 human endothelial cell line by promoting caspase-3 activation 16 and release of mitochondrial cytochrome c, 16,18 hallmarks of cellular suicide. The mitochondrial damage induced by NAMI-A 16 is compatible with the effect of 20 -50 M CTZ, which induces glycolysis-related hexokinase detachment from mitochondria and loss of viability in B16 melanoma. 8 Since apoptosis induced by 50 M KTZ is decreased in colorectal and hepatocellu...

The mechanism of antimalarial action of the ruthenium(II)–chloroquine complex [RuCl2(CQ)]2

“…We have previously discussed the concept of enhancing the activity of organic compounds of known therapeutic value by coordination to a metalcontaining fragment through a metal-drug synergy [21,22]. We demonstrated the merit of this approach against Trypanosoma cruzi, the causative agent of Chagas disease, using metal complexes of clotrimazole and ketoconazole [23][24][25][26]; some of those complexes were also found to be active as antitumor agents [27]. We also modified CQ through coordination to metalcontaining fragments, notably ruthenium [28], rhodium [28], and gold [29,30], and found enhanced antimalarial activity in several instances.…”

Cyclin D1 overexpression induces epidermal growth factor-independent resistance to apoptosis linked to BCL-2 in human A431 carcinoma

“…40 Although humanized monoclonal antibodies against the EGF receptor are a promising treatment against EGF-R overexpressing tumors, there are reports of resistance to this treatment. 41 Since cyclin D1 overexpression appears to obviate the need for EGF survival signalling, by inducing bcl-2 in tumors, our results suggest potentiating the efficacy of anti-cancer therapies 41 with antisense strategies directed against bcl-2/bcl-xL 25 to overcome resistance in tumors in which anti-apoptotic signalling through the EGF receptor is bypassed by cyclin D1/bcl-2 overexpression.…”

DN‐R175H p53 mutation is more effective than p53 interference in inducing epithelial disorganization and activation of proliferation signals in human carcinoma cells: Role of E‐cadherin

“…This was investigated by LSC. 28 Whereas wt p53 cells showed a G11S1G2% distribution of 54.2 1 25.6 1 20.9, a G11S1G2 distribution of 34.9 1 35.0 1 31.4, was found in mutant p53 cells (Fig. 2c).…”

“…Every sample was scanned using identical nonsaturating fluorescence settings, to allow quantitative comparisons to be made. 28 To analyze fluorescence changes on individual cells, clustered aggregates were gated, so as to include as many individual contoured cells as possible and quantitate integral (total fluorescence within the integral contour) and maximal pixels (highest localized fluorescence within the threshold contour). After the indicated culture conditions, cells attached to LabTek multiwell plates were fixed in 4% paraformaldehyde in phosphate-buffered saline (PBS), followed by permeabilization with 0.25% Triton X-100, washing in PBS, blocking in 5% albumin (in PBS), then reacted with either: (i) monospecific antibody to the phosphorylated (at Tyr 992) EGF-Receptor (Cat # 2235, from Cell Signaling Technologies, Boston, MA); (ii) rabbit antibody to human cyclin A (SC-751); (iii) rabbit antibody against MMP-9 (SC-10737) from Santa Cruz Biotechnology (Santa Cruz, CA).…”