Cannabinoid Combination Induces Cytoplasmic Vacuolation in MCF-7 Breast Cancer Cells

This study evaluated the synergistic anti-cancer potential of cannabinoid combinations across the MDA-MB-231 and MCF-7 human breast cancer cell lines. Cannabinoids were combined and their synergistic interactions were evaluated using median effect analysis. The most promising cannabinoid combination (C6) consisted of tetrahydrocannabinol, cannabigerol (CBG), cannabinol (CBN), and cannabidiol (CBD), and displayed favorable dose reduction indices and limited cytotoxicity against the non-cancerous breast cell line, MCF-10A. C6 exerted its effects in the MCF-7 cell line by inducing cell cycle arrest in the G2 phase, followed by the induction of apoptosis. Morphological observations indicated the induction of cytoplasmic vacuolation, with further investigation suggesting that the vacuole membrane was derived from the endoplasmic reticulum. In addition, lipid accumulation, increased lysosome size, and significant increases in the endoplasmic reticulum chaperone protein glucose-regulated protein 78 (GRP78) expression were also observed. The selectivity and ability of cannabinoids to halt cancer cell proliferation via pathways resembling apoptosis, autophagy, and paraptosis shows promise for cannabinoid use in standardized breast cancer treatment.

Synergistic Antitumor Effects of Berbamine and Paclitaxel through ROS/Akt Pathway in Glioma Cells

In our preliminary study, Berbamine (BA), one of the most commonly used traditional Chinese medicines, was effective in inducing the intracellular ROS levels. Since the regulation of cellular antioxidant capacity is crucial to the sensitivity of Ptx, it is feasible to propose that sensitizing cells to Ptx can be achieved through increasing the antioxidant capacity by codelivering BA. Cytotoxicity test demonstrates that either single or combinational treatment of BA and Ptx dose-dependently inhibits the proliferation of U-87 cells. Median-effect analysis clearly proves the synergistic anticancer effect between BA and Ptx. Combinational treatment of both drugs induced more intracellular ROS generation than either of the drugs did. Cotreatment of NAC could partially reverse the ROS generation and ameliorate the cytotoxicity induced by BA plus Ptx. Moreover, sequential activation of ROS-dependent phosphor-Akt expression was dose-dependently inhibited by the combinational application of BA and Ptx, which was more significantly effective than the single treatment of either BA or Ptx. Additionally, the coadministration of BA and Ptx shows the strongest tumor delaying effect in a U87 xenograft model, demonstrating the synergism between two drugs. Therefore, BA is a promising adjuvant to traditional chemotherapy, especially in combination with Ptx, to treat malignant glioma.

Pre-Clinical Development of Suberoylanilide Hydroxamic Acid (SAHA, Vorinostat ™) for the Treatment of Pediatric Acute Leukemias.

Acute leukemia is the most common malignancy of childhood and despite a good outcome for the majority of patients, a proportion of patients has high-risk features, and a very poor prognosis for ultimate cure. As such, novel approaches to therapy and new agents are clearly needed to improve the efficacy and quality of treatment available. We are investigating the utility of several histone deacetylase inhibitors (HDACIs) in the treatment of pediatric acute leukemias. Two HDACIs, suberoylanilide hydroxamic acid (SAHA, Vorinostat™) and MS-275, exhibited broad spectrum anti-tumor activity against a panel of 12 pediatric ALL and 8 AML cell lines representing different cell lineages and stages of development, with clinically achievable IC50 values of approximately 200–900nM. Both agents induced apoptosis in a dose-dependent manner. However, SAHA and MS-275 had differential effects on cell cycle progression and differentiation. Treatment with MS-275 resulted in sustained accumulation of cells in G1 phase and cell line-specific changes in the expression of multiple hematopoietic differentiation markers, including HLA-DR, CD11b, CD13, CD33, and CD61. Differentiation of both AML and ALL cell lines was induced. In contrast, treatment with SAHA either had no effect on cell cycle distribution or caused a transient arrest in G1 phase, which was reversible within 24–48 hours. In addition, only minimal changes in the expression of defined hematopoietic differentiation markers were observed following treatment with SAHA. These data suggest that the anti-leukemia effects mediated by SAHA and MS-275 occur by different biochemical and cellular mechanisms. Consistent with this hypothesis, SAHA and MS-275 exhibited synergistic anti-leukemic activity in vitro in a sequence dependent-manner, with a mean combination index of 0.666 +/− 0.048 based on median effect analysis. Sequence-dependent synergy was noted in a variety of T-cell and pre-B cell lines, including cell lines possessing MLL translocations. Both SAHA and MS-275 exhibited synergistic interactions with drugs representing the topoisomerase II, DNA methyltransferase, and proteosome inhibitor classes based on median effect analysis and/or the universal response surface approach. Detailed data demonstrating the mechanism(s) of HDACI-mediated anti-leukemic synergy and sequence-dependence with these other agents will be presented.