Apoptosis-inducing Properties Research Articles

Cytotoxic and apoptosis-inducing properties of a C21-steroidal glycoside isolated from the roots of Cynanchum auriculatum

The present study aimed to investigate the anti-cancer effect of a C21-steroidal glycoside (CG) isolated from the roots of Cynanchum auriculatum. CG was able to inhibit the growth of human cancer cells (SGC-7901 cells) in a concentration and time-dependent manner in vitro. SGC-7901 cells exposed to CG (10.8 and 21.6 μM) exhibited typical morphological apoptosis characteristics, such as nuclear-chromatin condensation and apoptotic body formation. Flow cytometric analysis showed that after treatment with CG at 10.8 and 21.6 μM for 24 h, the percentage of apoptotic cells increased to 30.4 and 43.2%, respectively, while the number of cells in the G0/G1, S and G2/M phases of the cell cycle decreased (P<0.05). Furthermore, treatment with CG at a concentration of 21.6 μM for 24 h significantly increased the expression of caspase-3 and the activity of caspase-3 was increased ∼3-fold in SGC-7901 cells. These results suggest that CG is the active anticancer component of the total C21-glycosides of the roots of Cynanchum auriculatum which is able to inhibit the growth of cancer cells and induce cancer cell apoptosis through caspase-3-dependent pathways.

Ginger Phytochemicals Exhibit Synergy to Inhibit Prostate Cancer Cell Proliferation

Dietary phytochemicals offer nontoxic therapeutic management as well as chemopreventive intervention for slow-growing prostate cancers. However, the limited success of several single-agent clinical trials suggest a paradigm shift that the health benefits of fruits and vegetables are not ascribable to individual phytochemicals, rather may be ascribed to synergistic interactions among them. We recently reported growth-inhibiting and apoptosis-inducing properties of ginger extract (GE) in in vitro and in vivo prostate cancer models. Nevertheless, the nature of interactions among the constituent ginger biophenolics, viz. 6-gingerol, 8-gingerol, 10-gingerol, and 6-shogoal, remains elusive. Here we show antiproliferative efficacy of the most-active GE biophenolics as single-agents and in binary combinations, and investigate the nature of their interactions using the Chou-Talalay combination index (CI) method. Our data demonstrate that binary combinations of ginger phytochemicals synergistically inhibit proliferation of PC-3 cells with CI values ranging from 0.03 to 0.88. To appreciate synergy among phytochemicals present in GE, the natural abundance of ginger biophenolics was quantitated using LC-UV/MS. Interestingly, combining GE with its constituents (in particular, 6-gingerol) resulted in significant augmentation of GE's antiproliferative activity. These data generate compelling grounds for further preclinical evaluation of GE alone and in combination with individual ginger biophenols for prostate cancer management.

Analysis of the Cytotoxic Potential of Anisomelic Acid Isolated from Anisomeles malabarica

Anisomelic acid (AA), one of the major compounds in Anisomeles malabarica, was tested for its cytotoxicity and apoptosis-inducing potential in breast and cervical cancer cells. The MTT assay for cell viability indicated that AA is cytotoxic to all of the four cell lines tested in a dose- and duration-dependent manner. Acridine Orange & Ethidium Bromide (AO & EB) and Hoechst 33258 staining of AA-treated cells revealed typical apoptotic morphology such as condensed chromatin and formation of apoptotic bodies. The comet assay revealed DNA strand break(s), indicating that AA induces DNA damage which culminates in apoptosis. Thus, the study revealed the anti-proliferative and apoptosis-inducing properties of AA in both breast and cervical cancer cells. Therefore, anisomelic acid offers potential for application in breast and cervical cancer therapy.

Resveratrol Affects Protein Kinase C Activity and Promotes Apoptosis in Human Colon Carcinoma Cells

Resveratrol has been reported to have potential chemopreventive and apoptosis-inducing properties in a variety of tumor cell lines. In this study, to investigate the effects of resveratrol on protein kinase C (PKC) activity and apoptosis in human colon carcinoma cells, we used HT-29 cells and examined the PKCα and ERK1/2 signaling pathways. To test the effects of resveratrol on the growth of HT- 29 cells, the cells were exposed to varying concentrations and assessed with the the MTT cell-viability assay. Fluorescence-activated cell sorter (FACS) analysis was applied to determine the effects of resveratrol on cell apoptosis. Western blotting was performed to determine the protein levels of PKCα and ERK1/2. In inhibition experiments, HT-29 cells were treated with Go?6976 or PD98059 for 30 min, followed by exposure to 200 μM resveratrol for 72 h. Resveratrol had a significant inhibitory effect on HT-29 cell growth. FACS revealed that resveratrol induced apoptosis. Western blotting showed that e phosphorylation of PKCα and ERK1/2 was significantly increased in response to resveratrol treatment. Pre-treatment with PKCα and ERK1/2 inhibitors (Go?6976 and PD98059) promoted apoptosis. Resveratrol has significant anti-proliferative effects on the colon cancer cell line HT-29. The PKC- ERK1/2 signaling pathway can partially mediate resveratrol-induced apoptosis of HT-29 cells.

A Prooxidant Mechanism for the Anticancer and Chemopreventive Properties of Plant Polyphenols

Plant-derived polyphenols, a prominent class of phytochemicals, are considered important components of human diet. A number of them are known to possess chemopreventive and therapeutic properties against various diseases including cancer. Several studies using cancer cell lines and animal models of carcinogenesis have shown that a wide range of polyphenols possess anticancer and apoptosis-inducing properties. Notably, an important aspect of the chemopreventive action of polyphenols is their differential activity in selectively targeting cancer cells while sparing normal cells. However, the mechanism through which polyphenols modulate their cancer cell selective anticancer effects has not been clearly delineated. In this regard, identification of a definitive anticancer mechanism of polyphenols would contribute to establish them as potent lead compounds for the synthesis of novel anticancer drugs. Although polyphenols are generally recognized as antioxidants, they also act as prooxidants inducing DNA degradation in the presence of metal ions such as copper. Based on our own observations and those of others, a mechanism for the anticancer properties of polyphenols that involves mobilization of chromatin-bound copper and consequent prooxidant action leading to cell death, was proposed. Since it is known that tissue and cellular copper levels are significantly elevated in a number of malignancies, cancer cells would be more subject to redox cycling between copper ions and polyphenols to generate reactive oxygen species (ROS) responsible for DNA breakage. This review discusses such a copper-dependent prooxidant mechanism of action of polyphenols that accounts for their observed chemopreventive properties, as also for their preferential cytotoxicity towards cancer cells.

Abstract A70: Ginger phytochemicals exhibit robust synergy to inhibit prostate cancer cell proliferation

Abstract An emerging notion accepts cancer as a preventable lifestyle disease. Fruits and vegetables offer non-toxic therapeutic options for prostate cancer in particular, since its slow growth offers a wide window for chemopreventive intervention. Fruits and vegetables contain various phytochemicals, including polyphenols and flavonoids that are well-known for their anti-inflammatory, and antiproliferative roles. However, the failure of several single-agent clinical trials has fueled a paradigm shift to appreciate that health benefits of fruits and vegetables are not ascribable to individual phytochemicals but rather to synergistic interactions among them. We recently reported the growth-inhibiting and apoptosis-inducing properties of whole ginger extract (GE) in in vitro and in vivo prostate cancer models. Nevertheless, the nature of interactions among the constituent ginger biophenolics, viz. 6-gingerol (6G), 8-gingerol (8G), 10-gingerol (10G), and 6-shogoal (6S), remains elusive. Here we show the antiproliferative efficacy of the most-active biophenolics present in GE as single-agents and in binary combinations, and investigate nature of their interactions using the Chou-Talalay combination-index (CI) method. Our data demonstrate that binary combinations of ginger phytochemicals synergistically inhibit cellular proliferation of human prostate cancer PC-3 cells with CI values ranging from 0.03 to 0.88. To appreciate synergy among ginger phytochemicals present in GE, the natural relative abundance of ginger biophenolics was quantitated using LC-UV/MS methods. Interestingly, combining GE with its constituents (in particular, 6G) resulted in significant augmentation of GE's antiproliferative activity. These data generate compelling grounds for further preclinical evaluation of GE alone and in combination with individual ginger biophenols for prostate cancer management. Citation Format: Sushma Reddy Gundala, Meera Brahmbhatt, Ritu Aneja. Ginger phytochemicals exhibit robust synergy to inhibit prostate cancer cell proliferation. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr A70.

Apoptosis initiation of β-ionone in SGC-7901 gastric carcinoma cancer cells via a PI3K-AKT pathway

β-ionone has been shown to hold potent anti-proliferative and apoptosis induction properties in vitro and in vivo. To investigate the effects of β-ionone on apoptosis initiation and its possible mechanisms of action, we qualified cell apoptosis, proteins related to apoptosis and a phosphatidylinositol 3-kinase (PI3K)-AKT pathway in human gastric adenocarcinoma cancer SGC-7901 cells. The results demonstrated that β-ionone-induced apoptosis in a dose-dependent manner in SGC-7901 cells treated with β-ionone (25, 50, 100 and 200μmol/L) for 24h. β-ionone was also shown to induce the expression of cleaved-caspase-3 and inhibit bcl-2 expression in SGC-7901 cells in a dose-dependent manner. The significantly decreased levels of p-PI3K and p-AKT expression were observed in SGC-7901 cells after β-ionone treatments in a time- and dose-dependent manner (P<0.01). Thus, the apoptosis induction in SGC-7901 cells by β-ionone may be regulated through a PI3K-AKT pathway. These results demonstrate a potential mechanism by which β-ionone to induce apoptosis initiation in SGC-7901 cells.

Geraniol modulates cell proliferation, apoptosis, inflammation, and angiogenesis during 7,12-dimethylbenz[a]anthracene-induced hamster buccal pouch carcinogenesis

Oral carcinogenesis, a multistep process with multifaceted etiology, arises due to accumulation of heterogeneous genetic changes in the genes involved in the basic cellular functions including cell division, differentiation, and cell death. These genetic changes in the affected cell progressively increase the cell proliferation, angiogenesis, and inhibition of apoptosis. The present study investigated the modulating effect of geraniol on the expression pattern of cell proliferative (PCNA, cyclin D1, c-fos), inflammatory (NF-κB, COX-2), apoptotic (p53, Bax, Bcl-2, caspase-3 and -9), and angiogenic (VEGF) markers in 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch carcinogenesis. Topical application of 0.5 % DMBA in liquid paraffin, three times a week, for 14 weeks, developed well-differentiated squamous cell carcinoma (SCC) in the buccal pouch of golden Syrian hamsters. All the hamsters treated with DMBA alone (100 %) developed oral tumors in the buccal pouch after 14 weeks. Over-expression of mutant p53, PCNA, Bcl-2, and VEGF accompanied by decreased expression of Bax were noticed in hamsters treated with DMBA alone. Increased expression of c-fos, COX-2, NF-κB, and cyclin D1 and decreased activities of caspase-3 and -9 were also noticed in hamsters treated with DMBA alone. Oral administration of geraniol at a dose of 250 mg/kg bw (body weight) not only completely prevented the formation of oral tumors but also prevented the deregulation in the expression of above mentioned molecular markers in hamsters treated with DMBA. The present results thus suggest that geraniol has potent anti-inflammatory, anti-angiogenic, anti-cell proliferative, and apoptosis-inducing properties in DMBA-induced hamster buccal pouch carcinogenesis.

Enhancement of cell permeabilization apoptosis-inducing activity of selenium nanoparticles by ATP surface decoration

A simple method for preparation of adenosine triphosphate (ATP) surface-functionalized selenium nanoparticles (SeNPs@ATP) with enhanced cell permeabilization and anticancer activity has been demonstrated in the study reported in this article. Spherical SeNPs were decorated with ATP by strong adsorption through an Se-N bond, leading to the highly stable structure of the conjugates. ATP surface decoration significantly enhanced the cellular uptake and anticancer activity of SeNPs. Induction of apoptosis in HepG2 human hepatocellular carcinoma cells by SeNPs@ATP was evidenced by accumulation of the sub-G1 cell population, phosphatidylserine exposure, DNA fragmentation, PARP cleavage and caspase activation. Further studies found that SeNPs@ATP treatment triggered the depletion of mitochondrial membrane potential and reactive oxygen species (ROS) overproduction. Our results demonstrate that the use of ATP as a surface decorator of SeNPs is a novel strategy to achieve anticancer synergy. SeNPs@ATP may be a candidate for further evaluation as a chemotherapeutic agent for human cancers. From the Clinical EditorIn this paper, adenosine triphosphate (ATP) surface-functionalized selenium nanoparticles are discussed as cell-penetrating anticancer agents. Conjugates are stable and ATP functionalization greatly enhances the apoptosis induction properties of the selenium nanoparticles in HepG2 human hepatocellular carcinoma cells.

Apoptosis induced by pneumolysin in human endothelial cells involves mitogen-activated protein kinase phosphorylation

Pneumolysin (Ply) is an essential virulence factor of S.pneumoniae, which can induce apoptosis in a variety of host cells to facilitate infection of pathogenic bacteria by as yet unclear mechanisms. To confirm the apoptosis-inducing properties of pneumolysin in endothelial cells, human umbilical vein endothelial cells (HUVECs) were exposed to pneumolysin. The proliferation of HUVECs was inhibited by pneumolysin in a dose- and time-dependent manner. Flow cytometry analysis and ultrastructural changes of the cells indicated the apoptotic response. Exposure to pneumolysin significantly increased the number of apoptotic cells and the activities of caspases-3 and -8. This change was associated with activation of p38 mitogen-activated protein kinase (MAPK) and suppression of extracellular signaling regulation kinase (ERK)1/2. Pre-exposure to the p38 MAPK inhibitor SB-203850 prevented human endothelial cells from apoptosis induced by pneumolysin. In conclusion, these findings demonstrate that pneumolysin induces apoptosis in endothelial cells and the involvement of p38 MAPK activation and ERK1/2 deactivation.

α-Santalol derivatives from Santalum album and their cytotoxic activities

A bioassay-guided fractionation of the heartwood of Santalum album led to the isolation of seven α-santalol derivatives including (9S,10E)-9-hydroxy-α-santalal, (10R,11S)-10,11-dihydroxy-α-santalol, (9E)-11,13-dihydroxy-α-santalol, and (10E)-12-hydroxy-α-santalic acid. Their structures were determined on the basis of results of spectroscopic analysis, including two-dimensional (2D) NMR spectroscopic data. The isolated compounds and derivatives were evaluated for cytotoxicity against HL-60 human promyelocytic leukemia cells and TIG-3 normal human diploid fibroblasts. Of these (9S,10E)-9-hydroxy-α-santalal, exhibited tumor-selective cytotoxicity. The apoptosis induction properties of sesquiterpenes with cytotoxic potency in HL-60 cells are also described.

DFNA5, a Gene Involved in Hearing Loss and Cancer: A Review

The DFNA5 gene was identified in 1998 as a gene that causes an autosomal dominant form of hearing impairment. Five different DFNA5 mutations have been found; each results in skipping of exon 8 at the messenger RNA level. This finding indicates that DFNA5-associated hearing loss is attributable to a highly specific gain-of-function mutation. Interestingly, later reports revealed that DFNA5 also plays a role in tumor biology. Recent data have shed more light on the biological function of DFNA5. Through a literature search, the current knowledge of this gene is reviewed. DFNA5 is the first gene for monogenic deafness that is known to involve apoptosis as a disease mechanism--a mechanism that was shown to be involved in frequent types of hearing loss caused by age, noise, or drugs. In line with its apoptosis-inducing properties, DFNA5 is a tumor suppressor gene with an important role in major types of tumors. DFNA5 is a tumor suppressor gene that is involved in apoptosis pathways and as such performs a basic role in cell survival. In view of the known role of apoptosis in several forms of hearing loss, DFNA5 may be a player in the underlying disease mechanisms.

Studies on the Secondary Metabolites of a Pseudoalteromonas sp. Isolated from Sediments Collected at the Northeastern Coast of Brazil

Continuing search for anticancer compounds from the marine environment, we have studied microorganisms that inhabit intertidal sediments of the northeastern Brazilian coast. Of the 32 strains isolated, 13 were selected for biological evaluation of their crude extracts. The acetate extract obtained from a Gram-negative bacterium was strongly active against cancer cell lines with IC(50) values that ranged from 0.04 (HL60 leukemia cells) to 0.26 μg/ml (MDA MB-435 melanoma cells). The bacterium was identified as a Pseudoalteromonas sp. based on 16S rRNA gene sequencing. A bioassay-guided fractionation of the active extract led to the isolation of prodigiosin, a well-known tripyrrole red pigment with immunosuppressive and anticancer activities. Further experiments with ErbB-2 overexpressing cell lines, including HB4a-C3.6 (moderate overexpression), HB4a-C5.2 (high overexpression), and the parental HB4a cell line, were performed. Prodigiosin was moderately active toward HB4a cells with an IC(50) of 4.6 μg/ml, while it was 115 and 18 times more active toward HB4a-C3.6 cells (IC(50) of 0.04 μg/ml) and HB4a-C5.2 (IC(50) of 0.26 μg/ml) cells, respectively. These data suggest that, in spite of its previously described apoptosis-inducing properties, prodigiosin can selectively recognize cells overexpressing ErbB-2, which could be highly appealing in human breast cancer therapy.

An Overview of Cancer Chemopreventive Potential and Safety of Proanthocyanidins

Cancer is a major public health problem worldwide. Over two-thirds of cancer-related deaths could most probably be prevented through lifestyle modification, particularly through dietary means. Proanthocyanidins (PAs), the most abundant polyphenolic substances after lignin in the plant kingdom, have been widely investigated for their chemopreventive potential. The PAs literature has, however, been mostly concerned with positive cardiovascular activities, and recent reviews about cancer chemoprevention are scarce. The present review highlights a series of in vitro and in vivo studies indicating (1) that PAs can act as anticarcinogenic agents through their antioxidant, apoptosis-inducing, immuno-modulating, and/or enzyme modulating properties, effects on epigenetics; and (2) that PAs could be particularly safe dietary compounds. These convergent data encourage further research to better understand the many aspects of cancer chemoprevention by PAs.

Eugenol Enhances the Chemotherapeutic Potential of Gemcitabine and Induces Anticarcinogenic and Anti-inflammatory Activity in Human Cervical Cancer Cells

Administration of natural or synthetic agents to inhibit, delay, block, or reverse the initiation and promotional events associated with carcinogenesis opens a new avenue for cancer prevention and treatment to reduce cancer morbidity and mortality. Eugenol, a potential chemopreventive agent, is a component of clove and several other spices such as basil, cinnamon, and bay leaves. A number of reports have shown that eugenol possesses antiseptic, analgesic, antibacterial, and anticancer properties. The present study was undertaken to evaluate the chemopreventive potential of eugenol alone and in combination with a chemotherapeutic agent such as gemcitabine. Eugenol showed dose-dependent selective cytotoxicity toward HeLa cells in comparison to normal cells, pointing to its safe cytotoxicity profile. A combination of eugenol and gemcitabine induced growth inhibition and apoptosis at lower concentrations, compared with the individual drugs. The analysis of the data using a combination index showed combination index values of <1 indicating strong synergistic interaction. The combination thus may enhance the efficacy of gemcitabine at lower doses and minimize the toxicity on normal cells. In addition, the expression analysis of genes involved in apoptosis and inflammation revealed significant downregulation of Bcl-2, COX-2, and IL-1β on treatment with eugenol. Thus, the results suggest that eugenol exerts its anticancer activities via apoptosis induction and anti-inflammatory properties and also provide the first evidence demonstrating synergism between eugenol and gemcitabine, which may enhance the therapeutic index of prevention and/or treatment of cervical cancer.

Effects of zerumbone on cisplatin-induced clastogenesis in Sprague-Dawley rats bone marrow cells

Zerumbone (ZER) is derived from Zingiber zerumbet smith from the Zingiberaceae family. It has been shown to have anti-cancer and apoptosis-inducing properties against various human tumour cells. The aim of our study was to assess the effect of ZER on cisplatin-induced clastogenesis in Sprague-Dawley rat bone marrow polychromatic erythrocytes (PCEs) using micronucleus test (MN). Animals treated with two ZER doses for 4 consecutive days plus a single dose of cisplatin following treatment, presented a non-significant effects of ZER on cisplatin-induced clastogenesis. The results also indicated that ZER has no clastogenic effects on rat bone marrow polychromatic erythrocytes after 4 days treatment with 250 and 500 mg/kg body weight when compared to one dose cisplatin of 45 mg/kg body weight. On the other hand, significant decrease in the number of PCE was observed in all treatment groups, indicating cytotoxicity of ZER and cisplatin. Under the present experimental conditions, ZER could not prevent cisplatin-induced clastogenesis in rat.

Anticancer Properties of an Important Drug Lead Podophyllotoxin Can Be Efficiently Mimicked by Diverse Heterocyclic Scaffolds Accessible via One-Step Synthesis

Structural simplification of an antimitotic natural product podophyllotoxin with mimetic heterocyclic scaffolds constructed using multicomponent reactions led to the identification of compounds exhibiting low nanomolar antiproliferative and apoptosis-inducing properties. The most potent compounds were found in the dihydropyridopyrazole, dihydropyridonaphthalene, dihydropyridoindole, and dihydropyridopyrimidine scaffold series. Biochemical mechanistic studies performed with dihydropyridopyrazole compounds showed that these heterocycles inhibit in vitro tubulin polymerization and disrupt the formation of mitotic spindles in dividing cells at low nanomolar concentrations, in a manner similar to podophyllotoxin itself. Separation of a racemic dihydropyridonaphthalene into individual enantiomers demonstrated that only the optical antipode matching the absolute configuration of podophyllotoxin possessed potent anticancer activity. Computer modeling, performed using the podophyllotoxin binding site on β-tubulin, provided a theoretical understanding of these successful experimental findings.

A pilot study on the DNA-protective, cytotoxic, and apoptosis-inducing properties of olive-leaf extracts

Leaves of olive trees are an abundant raw material in the Mediterranean basin. They contain large amounts of potentially useful phytochemicals and could play beneficial roles in health care. In the present study, the principal bioactive phenols in olive-leaf extracts (OLEs) have been identified and quantified, and their genotoxic/antigenotoxic, cytotoxic and apoptotic effects have been assessed. The Somatic Mutation and Recombination Test (SMART) in wing imaginal discs of Drosophila melanogaster has been performed to test the possible genotoxicity of overall OLE and the individual components oleuropein and luteolin at different concentrations. The same assay was able to detect antigenotoxic activity against hydrogen peroxide as oxidative genotoxicant. None of the extracts/phenols tested showed significant mutagenic activity. This fact, together with the antigenotoxic activity against H 2O 2 detected for all these extracts/phenols, confirmed the safety of OLE, oleuropein and luteolin in terms of DNA protection. HL60 human promyelocytic leukemia cells were used to assess the cytotoxic effects of the extracts/phenols. OLE, oleuropein and luteolin showed a dose-dependent cytotoxic effect with different IC50 (10 μl/ml, 170 μM, and 40 μM, respectively). DNA fragmentation patterns and cell staining with acridine orange and ethidium bromide indicated that the mechanism for the cytotoxic effect of OLE, oleuropein and luteolin was the apoptotic pathway, with DNA laddering and cytoplasmic and nuclear changes. These results could help explain the mechanism of action that underlies the beneficial effect of OLE, proposed as a nutraceutical in the prevention of human cancer.

Structural Simplification of Bioactive Natural Products with Multicomponent Synthesis. 3. Fused Uracil-Containing Heterocycles as Novel Topoisomerase-Targeting Agents

After the initial discovery of antiproliferative and apoptosis-inducing properties of a camptothecin-inspired pentacycle based on a 1H-indeno[2',1':5,6]dihydropyrido[2,3-d]pyrimidine scaffold, a library of its analogues as well as their oxidized planar counterparts were prepared utilizing a practical multicomponent synthetic protocol. The synthesized compounds exhibited submicromolar to low micromolar antiproliferative potencies toward a panel of human cancer cell lines. Biochemical experiments are consistent with the dihydropyridine library members undergoing intracellular oxidation to the corresponding planar pyridines, which then inhibit topoisomerase II activity, leading to inhibition of proliferation and cell death. Because of facile synthetic preparation and promising antitopoisomerase activity, both the dihydropyridine and planar pyridine-based compounds represent a convenient starting point for anticancer drug discovery.

Antileukemic activity and cellular effects of rhodium(III) crown thiaether complexes

The cytostatic properties of novel rhodium(III) thiacrown ether complexes [RhCl(LL)([9]aneS(3))](n+) with either aromatic κ(2)N ligands (n = 2) or anionic chelate ligands (n = 1) have been investigated for the human cancer cell lines HT-29 and MCF-7 and for immortalized HEK-293 cells. Taken together with literature IC(50) values for analogous complexes with polypyridyl ligands or 1,4-dithiane, the in vitro assays indicate that dicationic complexes with soft κ(2)N (imino) or κ(2)S (thiaether) ligands exhibit significantly higher antiproliferative effects than those with hard κ(2)N (amino) ligands. Dicationic complexes are more active than monocationic complexes with similar ligands. Pronounced apoptosis-inducing properties towards Jurkat cells were established for complexes with LL = bpm, dpq, and 1,4-dithiane. The order of activity (bpm > 1,4-dithiane > dpq > bpy) contrasts to that observed for adhesive cancer cells (bpm > bpy, 1,4-dithiane > dpq). Necrosis is insignificant in all cases. The percentage of Jurkat cells exhibiting apoptosis after 24 or 48 h incubation periods is directly correlated to the percentage of cells exhibiting high levels of reactive oxygen species. As established by online monitoring with a sensor chip system, treatment of MCF-7 cells with the bpm and 1,4-dithiane complexes leads to a significant and permanent concentration-dependent decrease in oxygen consumption and cellular adhesion.