Pre-clinical and retrospective studies of patients using statins to reduce plasma cholesterol have suggested that statins may be useful to treat cancer. However, prospective clinical trials have yet to demonstrate significant efficacy. We have previously shown that this is in part because a hydrophobic statin with a long half-life is necessary. Pitavastatin, the only statin with this profile, has not undergone clinical evaluation in oncology. The target of pitavastatin, hydroxymethylglutarate coenzyme-A reductase (HMGCR), was found to be over-expressed in all ovarian cancer cell lines examined and upregulated by mutated TP53, a gene commonly altered in ovarian cancer. Pitavastatin-induced apoptosis was blocked by geranylgeraniol and mevalonate, products of the HMGCR pathway, confirming that pitavastatin causes cell death through inhibition of HMGCR. Solvent extracts of human and mouse food were also able to block pitavastatin-induced apoptosis, suggesting diet might influence the outcome of clinical trials. When nude mice were maintained on a diet lacking geranylgeraniol, oral pitavastatin caused regression of Ovcar-4 tumour xenografts. However, when the animal diet was supplemented with geranylgeraniol, pitavastatin failed to prevent tumour growth. This suggests that a diet containing geranylgeraniol can limit the anti-tumour activity of pitavastatin and diet should be controlled in clinical trials of statins.

Statins are widely used to treat hypercholesterolaemia. However, by inhibiting the production of mevalonate, they also reduce the production of several isoprenoids that are necessary for the function of small GTPase oncogenes such as Ras. As such, statins offer an attractive way to inhibit an "undruggable" target, suggesting that they may be usefully repurposed to treat cancer. However, despite numerous studies, there is still no consensus whether statins are useful in the oncology arena. Numerous preclinical studies have provided evidence justifying the evaluation of statins in cancer patients. Some retrospective studies of patients taking statins to control cholesterol have identified a reduced risk of cancer mortality. However, prospective clinical studies have mostly not been successful. We believe that this has occurred because many of the prospective clinical trials have been poorly designed. Many of these trials have failed to take into account some or all of the factors identified in preclinical studies that are likely to be necessary for statins to be efficacious. We suggest an improved trial design which takes these factors into account. Importantly, we suggest that the design of clinical trials of drugs which are being considered for repurposing should not assume it is appropriate to use them in the same way as they are used in their original indication. Rather, such trials deserve to be informed by preclinical studies that are comparable to those for any novel drug.

Only 40% of patients with advanced ovarian cancer survive more than 5 years. We have previously shown that pitavastatin induces regression of ovarian cancer xenografts in mice. To evaluate whether the response of ovarian cancer cells to pitavastatin is potentiated by farnesyl diphosphate synthase inhibitors or geranylgeraniol transferase I inhibitors, we evaluated combinations of pitavastatin with zoledronic acid, risedronate and GGTI-2133 in a panel of ovarian cancer cells. Pitavastatin (IC50 = 0.6–14 μM), zoledronic acid (IC50 = 21–57 μM), risedronate (IC50 > 100 μM) or GGTI-2133 (IC50 > 25 μM) inhibited the growth of ovarian cancer cell cultures. Combinations of pitavastatin with zoledronic acid displayed additive or synergistic effects in cell growth assays in 10 of 11 cell lines evaluated as well as in trypan blue exclusion, cellular ATP or caspase 3/7, 8 and 9 assays. Pitavastatin reduced levels of GGT-IIβ and the membrane localization of several small GTPases and this was potentiated by zoledronic acid. siRNA to GGT-Iβ and GGT-IIβ used in combination, but not when used individually, significantly increased the sensitivity of cells to pitavastatin. These data suggest that zoledronic acid, a drug already in clinical use, may be usefully combined with pitavastatin in the treatment of ovarian cancer.

Hepatocellular carcinoma is an aggressive form of liver cancer that displays minimal symptoms until its late stages. Unfortunately, patient prognosis still remains poor with only 10% of patients surviving more than five years after diagnosis. Current chemotherapies alone are not offering efficient treatment, hence alternative therapeutic approaches are urgently required. In this work, we highlight the potential of combination of treatment of hepatocellular carcinoma with existing chemotherapies in combination with pro-apoptotic factor cytochrome C. In order to allow cytochrome C to cross the cellular membrane and become internalized, it has been immobilised onto the surface of hybrid iron oxide-gold nanoparticles. This novel approach has been tested in vitro on HepG2, Huh-7D and SK-hep-1 cell lines in order to elucidate potential as a possible alternative therapy with greater efficacy. The data from our studies show consistently that combining treatment of clinically used anticancer agents (doxorubicin, paclitaxel, oxaliplatin, vinblastine and vincristine) significantly increases the levels of apoptosis within the cell lines, which leads to cellular death. Hence, this combined approach may hold promise for future treatment regimes.

BackgroundBH3 mimetics are a class of drugs that antagonize the Bcl-2 family of apoptosis inhibitors. We have previously shown that these compounds can potentiate the activity of carboplatin against several ovarian cancer cell lines. However, recent clinical studies have highlighted that BH3 mimetics which antagonise Bcl-XL are associated with significant thrombocytopenia. This has led to the development of ABT-199 which specifically inhibits Bcl-2. Unfortunately, Bcl-XL appears to be more frequently deregulated in ovarian cancer than Bcl-2. We therefore compared the ability of ABT-199, and the Bcl-XL selective compound WEHI-539, to potentiate the activity of carboplatin in ovarian cancer cell lines.MethodsWEHI-539, ABT-737 and ABT-199 were tested in combination with carboplatin using a panel of 6 ovarian cancer cell lines. The activity of the drugs was evaluated using cell growth assays, staining with trypan bue and measurement of apoptosis by measuring caspase 3/7 activity, PARP cleavage and annexin-V/propidium iodide staining.ResultsWe found that WEHI-539 and ABT-737, but not ABT-199, were synergistic with carboplatin in cell growth assays and potentiated cell death when assessed by trypan blue staining. Furthermore, WEHI-539 and ABT-737 augmented carboplatin induced caspase 3/7 activity, PARP cleavage and annexin V labelling, but ABT-199 failed to do so.ConclusionsThese observations suggest that compounds which target Bcl-XL are necessary if BH3 mimetics are to be successfully used to treat patients with ovarian cancer and this highlights the need to develop strategies to minimize thrombocytopenia induced by such compounds.

The survival rate for patients with ovarian cancer has changed little in the past three decades since the introduction of platinum-based chemotherapy and new drugs are needed. Statins are drugs used for the treatment and prevention of cardiovascular diseases. Recent work from our laboratory has shown that pitavastatin has potential as a treatment for ovarian cancer if dietary geranylgeraniol is controlled. However, relatively high doses of statins are required to induce apoptosis in cancer cells, increasing the risk of myopathy, the most common adverse effect associated with statins. This makes it desirable to identify drugs which reduce the dose of pitavastatin necessary to treat cancer. A drug-repositioning strategy was employed to identify suitable candidates. Screening a custom library of 100 off-patent drugs for synergistic activity with pitavastatin identified prednisolone as the most prominent hit. Prednisolone potentiated the activity of pitavastatin in several assays measuring the growth, survival or apoptosis in several ovarian cancer cells lines. Prednisolone, alone or in some cases in combination with pitavastatin, reduced the expression of genes encoding enzymes in the mevalonate pathway, providing a mechanistic explanation for the synergy.

Triclisia subcordata Oliv (Menispermeaceae) is used in herbal medicine for the treatment of cancer and other diseases in Africa. This study aims to isolate minor alkaloids present in this plant and assay their cytotoxic activities. Isochondodendrine and 2 0 -norcocsuline as two minor alkaloids together with the abundant cycleanine were isolated and identified by mass spectrometry and NMR spectroscopy. Both isochondodendrine and 2 0 -norcocsuline exhibited in vitro cytotoxicity in four ovarian cancer cell lines (A2780, IGROV-1, OVCAR-8, and OVCAR-4) with IC 50 ranges of 3.5-17 mM and 0.8-6.2 mM respectively.These alkaloids showed mostly slightly weaker potencies when tested using normal human ovarian epithelial cells, IC 50 ¼ 10.5 AE 1.2 mM and 8.0 AE 0.2 mM for isochondodendrine and 2 0 -norcocsuline, respectively. The alkaloids induced apoptosis in ovarian cancer cells because they activated caspases 3/7, induced cleavage of PARP, increased the subG 1 population in cell cycle analysis and increased Annexin V/propidium iodide staining. These observations suggest that isochondodendrine and 2 0 -norcocsuline contributing to the cytotoxic activity of T. subcordata may be suitable starting points for the future development of novel therapeutics to treat ovarian cancer.

Triclisia subcordata Oliv (Menispermeaceae) is an African medicinal plant traditionally used for the treatment of various diseases, including cancer. This study aims to isolate and identify minor alkaloids present in this plant and assayed their anticancer activities. Isochondodendrine (1) and 2′-norcocsuline (2) as two minor alkaloids together with the abundant cycleanine (3) [1] were isolated and identified by mass spectrometry and nuclear magnetic resonance spectroscopy. Both isochondodendrine and 2′-norcocsuline exhibited potent in vitro cytotoxicity in four ovarian cancer cell lines (A2780, Igrov-1, Ovcar-8, and Ovcar-4) with IC 50 range of 3.5-17 M and 0.8-2.9 µM by use of sulforhodamine B dye assay, respectively. The IC 50 in cell growth assays using normal human ovarian epithelial cells were 10.5±1.2 µM and 8.0±0.2 µM for isochondodendrine and 2′-norcocsuline, respectively. These alkaloids showed greater potencies for the cancer cells compared to normal cells. Apoptosis induction of these alkaloids was studied by caspase activity assay, western blot, and flow cytometry. They induced apoptosis in ovarian cancer cells by activations of caspases 3/7, cleavage of PARP, increase in subG 1 cell cycle phase and increase in both early and late apoptotic cells. Therefore, isochondodendrine and 2′norcocsuline are among the less abundant in T. subcordata, which also contribute to its cytotoxic activity and can be potential hit compounds for future development for the treatment of ovarian cancer.