Potentiation of Cisplatin Activity in Colorectal Cancer Cells by Lovastatin

Cisplatin (CIS) is an anticancer drugs used in the treatment of several solid tumors with nephrotoxicity as its main toxic effect. The current study was directed to assess the role of hypolipidemic drug (lovastatin) on sensitization of human colorectal cancer cells (HCT -116) to the action of CIS. This study assessed the action of lovastatin on sensitization of colorectal cancer cells to cisplatin by examining cisplatin cytotoxicity, cisplatin cellular uptake and P-glycoprotein (P-gp) activity in presence and absence of Lovastatin 10 and 30 ug/ml. Lovastatin treatment at dose level of 10 and 30 µg/ml potentiated the cytocidal effect of cisplatin against the growth of HCT-116 cells with IC50 7.3 and 5.4 µg/ml, respectively compare to 18 µg/ml after treatment with cisplatin alone. Moreover, lovastatin increased the uptake of cisplatin into colorectal cancer cells with marked inhibition of P-glycoprotein pump. On conclusion Lovastatin treatment increases the antiproliferative activity of cisplatin against the growth of colorectal cancer cells due to inhibition the activity P-glycoprotein pump with marked increase in its cellular uptake.

Lovastatin interferes with the infarct size-limiting effect of ischemic preconditioning and postconditioning in rat hearts

Statins have been shown to be cardioprotective; however, their interaction with endogenous cardioprotection by ischemic preconditioning and postconditioning is not known. In the present study, we examined if acute and chronic administration of the 3-hydroxy-3-methylglutaryl CoA reductase inhibitor lovastatin affected the infarct size-limiting effect of ischemic preconditioning and postconditioning in rat hearts. Wistar rats were randomly assigned to the following three groups: 1) vehicle (1% methylcellulose per os for 12 days), 2) chronic lovastatin (15 mg·kg−1·day−1 per os for 12 days), and 3) acute lovastatin (1% methylcellulose per os for 12 days and 50 μmol/l lovastatin in the perfusate). Hearts isolated from the three groups were either subjected to a nonconditioning (aerobic perfusion followed by 30-min coronary occlusion and 120-min reperfusion, i.e., test ischemia-reperfusion), preconditioning (three intermittent periods of 5-min ischemia-reperfusion cycles before test ischemia-reperfusion), or postconditioning (six cycles of 10-s ischemia-reperfusion after test ischemia) perfusion protocol. Preconditioning and postconditioning significantly decreased infarct size in vehicle-treated hearts. However, preconditioning failed to decrease infarct size in acute lovastatin-treated hearts, but the effect of postconditioning remained unchanged. Chronic lovastatin treatment abolished postconditioning but not preconditioning; however, it decreased infarct size in the nonconditioned group. Myocardial levels of coenzyme Q9 were decreased in both acute and chronic lovastatin-treated rats. Western blot analysis revealed that both acute and chronic lovastatin treatment attenuated the phoshorylation of Akt; however, acute but not chronic lovastatin treatment increased the phosphorylation of p42 MAPK/ERK. We conclude that, although lovastatin may lead to cardioprotection, it interferes with the mechanisms of cardiac adaptation to ischemic stress.

Influences of Lovastatin on membrane ion flow and intracellular signaling in breast cancer cells

Lovastatin, an inhibitor of cellular cholesterol synthesis, has an apparent anti-cancer property, but the detailed mechanisms of its anti-cancer effects remain poorly understood. We investigated the molecular mechanism of Lovastatin anti-tumor function through the study of its effect on membrane ion flow, gap junctional intercellular communication (GJIC), and the pathways of related signals in MCF-7 mammary cancer cells. After treatment for 24–72 h with 4, 8 or 16 μmol/L Lovastatin, cellular proliferation was examined via the MTT assay, and changes in membrane potential and cellular [Ca2+]i were monitored using confocal laser microscopy. In addition, the expression of plasma membrane calcium ATPase isoform 1 (PMCA1) mRNA was analyzed via RT-PCR, the GJIC function was examined using the scrape-loading dye transfer (SLDT) technique, and MAPK phosphorylation levels were tested with the kinase activity assay. The results showed that Lovastatin treatment significantly inhibited the growth of MCF-7 breast cancer cells. It also increased the negative value of the membrane potential, leading to the hyperpolarization of cells. Moreover, Lovastatin treatment continuously enhanced [Ca2+]i, although the levels of PMCA1 mRNA were unchanged. GJIC was also upregulated in MCF-7 cells, with transfer of LY Fluorescence reaching 4 to 5 rows of cells from the scraped line after treatment with 16 μmol/L Lovastatin for 72 h. Finally, downregulation of ERK1 and p38MAPK phosphorylation were found in Lovastatin-treated MCF-7 cells. It could be deduced that Lovastatin can induce changes in cellular hyperpolarization and intracellular Ca2+ distributions, and increase GJIC function. These effects may result in changes in the downstream signal cascade, inhibiting the growth of MCF-7 cells.

Targeting RAS Signaling in Multiple Myeloma (MM): Synergistic Inhibition by Co-Treatment with the MEK Inhibitor U0126 and Prenylation Inhibitors.

Multiple myeloma (MM) is a fatal hematological malignancy associated with disruption of RAS-to-MAP kinase (MAPK/ERK) signaling. Prenylation inhibitors such as farnesyltransferase inhibitors (FTIs) and the competitive HMG-CoA reductase inhibitor lovastatin have been shown to block RAS post-translational modification and thus transforming ability. Targeting down-stream members of the RAS signaling cascade with compounds such as the MEK inhibitor U0126 is another strategy used to successfully disrupt oncogenic RAS signal transduction. In order to assess the effects of co-treating MM cells with U0126 and prenylation inhibitors (e.g. FTI L-744,832 and lovastatin), six MM cell lines were assayed for viability using the MTT assay, induction of apoptosis by TUNEL assay, and MEK activation by a phospho-MEK-specific FACS assay. Treated cells were also subjected to Western blotting to determine levels of phosphorylated MAP kinase as well as processed and unprocessed RAS and RAS-related proteins. Co-treating MM cells with U0126 and FTI L-744,832 or lovastatin synergistically inhibited MM cell proliferation. Incubation of NCI-H929 cells with U0126 caused a concentration dependent increase of cells in the G0/G1 phase of the cell cycle. Accordingly, 48 h treatment of NCI-H929 cells with 20 μM U0126 caused a reduction in activated MEK in both G0/G1 and G2/M cell cycle phases (41.9 and 39.5%, respectively) while 50 μM reduced activated MEK levels by 64.8% in G0/G1 and 74.5% in G2/M. Lovastatin treatment (48 h, 10 μM) of NCI-H929 led to an accumulation of cells at the G1/S boundary of the cell cycle and >90% loss of activated MEK in both G0/G1 and G2/M. Lovastatin-induced changes in cell cycle distribution and loss of MEK activation could not be rescued by farnesyl pyrophosphate, but were restored to levels similar to those measured in untreated cells by geranylgeranyl pyrophosphate or mevalonate. Co-treating OPM-2 cells 48 h with 10 μM lovastatin and 50 μM U0126 led to >96% decrease in activated MEK in G0/G1 and >76% reduction in G2/M. Lovastatin treatment also caused a loss of prenylated RAS and RAS-family proteins as demonstrated by Western blot analyses. Additionally, Western blotting showed that U0126 treatment (5 μM, 30 min) alone or in combination with lovastatin (5 μM, 30 min) blocked IL-6 stimulated activation of MAP kinase in OPM-2 cells but had no effect on pAKT levels. Our results support that inhibition of RAS processing and down-stream signaling are the major mechanisms of action through which U0126 and lovastatin synergistically inhibit MM cell growth. Furthermore, these data demonstrate the potential therapeutic usefulness of these compounds in the treatment of multiple myeloma.