Nuclear Transcription Factor Kappa B Downregulation Reduces Chemoresistance in Bone Marrow-derived Cells Through P-glycoprotein Modulation

Development of Polymersomes Co-Delivering Doxorubicin and Melittin to Overcome Multidrug Resistance

Multidrug resistance (MDR) is one of the major barriers in chemotherapy. It is often related to the overexpression of efflux receptors such as P-glycoprotein (P-gp). Overexpressed efflux receptors inhibit chemotherapeutic efficacy by pumping out intracellularly delivered anticancer drugs. In P-gp-mediated MDR-related pathways, PI3K/Akt and NF-kB pathways are commonly activated signaling pathways, but these pathways are downregulated by melittin, a main component of bee venom. In this study, a polymersome based on a poly (lactic acid) (PLA)-hyaluronic acid (HA) (20k-10k) di-block copolymer and encapsulating melittin and doxorubicin was developed to overcome anticancer resistance and enhance chemotherapeutic efficacy. Through the simultaneous delivery of doxorubicin and melittin, PI3K/Akt and NF-κB pathways could be effectively inhibited, thereby downregulating P-gp and successfully enhancing chemotherapeutic efficacy. In conclusion, a polymersome carrying an anticancer drug and melittin could overcome MDR by regulating P-gp overexpression pathways.

Borneol and Tetrandrine Modulate the Blood-Brain Barrier and Blood-Tumor Barrier to Improve the Therapeutic Efficacy of 5-Fluorouracil in Brain Metastasis

The efficacy of chemotherapeutic drugs for the treatment of brain metastasis may be compromised by the blood–brain barrier (BBB) and blood–tumor barrier (BTB). P-glycoprotein (P-gp) is a multidrug resistance protein that potentially limits the penetration of chemotherapeutics through the BBB and BTB. 5-Fluorouracil (5-FU) is widely used to treat cancer. Bioactive constituents of medicinal herbs, such as borneol and tetrandrine, potentially improve drug penetration through the BBB and BTB. We hypothesized that borneol and tetrandrine might modulate the BBB and BTB to enhance 5-FU penetration into the brain. To investigate this, in vitro and in vivo models were developed to explore the modulatory effects of borneol and tetrandrine on 5-FU penetration through the BBB and BTB. In the in vitro models, barrier integrity, cell viability, barrier penetration, P-gp activity, and NF-κB expression were assessed. In the in vivo brain metastasis models, cancer cells were injected into the internal carotid artery to evaluate tumor growth. The experimental results demonstrated that borneol and borneol + tetrandrine reduced BBB integrity. The efflux pump function of P-gp was partially inhibited by tetrandrine and borneol + tetrandrine. In the in vivo experiment, borneol + tetrandrine effectively prolonged survival without compromising body weight. In conclusion, BBB and BTB integrity was modulated by borneol and borneol + tetrandrine. The combination of borneol and tetrandrine could be used to improve the chemotherapeutic control of brain metastasis.

Cajanol Sensitizes A2780/Taxol Cells to Paclitaxel by Inhibiting the PI3K/Akt/NF-κB Signaling Pathway

Ovarian cancer is the second most common gynecological malignancy, and one of the most deadly. The bottleneck restricting the treatment of ovarian cancer is its multi-drug resistance to chemotherapy. Cajanol is an isoflavone from pigeon pea (Cajanus cajan) that has been reported to have anti-tumor activity. In this work, we evaluate the effect of cajanol in reversing paclitaxel resistance of the A2780/Taxol ovarian cancer cell line in vitro and in vivo, and we discuss its mechanism of action. We found that 8 μM cajanol significantly restored the sensitivity of A2780/Taxol cells to paclitaxel, and in vivo experiments demonstrated that the combination of 0.5 mM/kg paclitaxel and 2 mM/kg cajanol significantly inhibited the growth of A2780/Taxol metastatic tumors in mice. Flow cytometry, fluorescence quantitative PCR, western blotting and immunohistochemical staining methods were used to study the mechanism of reversing paclitaxel resistance with cajanol. First, we determined that cajanol inhibits paclitaxel efflux in A2780/Taxol cells by down-regulating permeability glycoprotein (P-gp) expression, and further found that cajanol can inhibit P-gp transcription and translation through the PI3K/Akt/NF-κB pathway. The results of this work are expected to provide a new candidate compound for the development of paclitaxel sensitizers.

Cardamonin inhibits the expression of P-glycoprotein and enhances the anti-proliferation of paclitaxel on SKOV3-Taxol cells

Paclitaxel is widely used in the first-line treatment of ovarian cancer. Nevertheless, the development of acquired resistance to paclitaxel is a major obstacle for the therapy in clinic. Cardamonin is a novel anticancer chalcone which exhibits a wide range of pharmacological activities. However, the effect of cardamonin on paclitaxel-resistant ovarian cancer cells and its underlying molecular mechanisms are unknown. Here, we revealed whether cardamonin had a resensitivity for paclitaxel and furtherly explored the underlying mechanisms on SKOV3-Taxol cells. Our results showed that cardamonin combined with paclitaxel had a synergistic effect of anti-proliferation in SKOV3-Taxol cells, and CI was less than one. Cells apoptosis and G2/M phase arrest were enhanced by cardamonin with paclitaxel in a concentration-dependent way on SKOV3-Taxol cells (P < 0.05). Cardamonin significantly increased drug accumulation in SKOV3-Taxol cells (P < 0.05). Similar to verapamil, cardamonin decreased MDR1 mRNA and P-gp expression (P < 0.05). Cardamonin restrained NF-κB activation in SKOV3-Taxol cells (P < 0.05). Inhibitory effect of P-gp and NF-κB p65 (nuclear protein) expression was enhanced by cardamonin combined with PDTC, a NF-κB inhibitor. Cardamonin significantly inhibited the upregulation of NF-κB p65 (nuclear protein) and P-gp expression induced by TNF-α (P < 0.05). Taken together, cardamonin enhanced the effect of paclitaxel on inhibiting cell proliferation, inducing apoptosis and G2/M phase arrest, and then strengthened the cytotoxic effect of paclitaxel in SKOV3-Taxol cells. The mechanism might be involved in inhibition of P-gp efflux pump, reducing MDR1 mRNA and P-gp expression by cardamonin via suppression of NF-κB activation in SKOV3-Taxol cells.

Ferulic acid reverses P-glycoprotein-mediated multidrug resistance via inhibition of PI3K/Akt/NF-κB signaling pathway

In this study, the modulatory effect of ferulic acid on P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) was examined in KB Ch^R8-5 resistant cells and drug-resistant tumor xenografts. We observed that ferulic acid enhanced the cytotoxicity of doxorubicin and vincristine in the P-gp overexpressing KB Ch^R8-5 cells. Further, ferulic acid enhances the doxorubicin induced γH2AX foci formation and synergistically augmented doxorubicin-induced apoptotic signaling in the drug-resistant cells. It has also been noticed that NF-κB nuclear translocation was suppressed by ferulic acid and that this response might be associated with the modulation of phosphatidyinositol 3-kinase (PI3K)/Akt/signaling pathway. We also found that ferulic acid and doxorubicin combination reduced the size of KB Ch^R8-5 tumor xenograft by threefold as compared to doxorubicin-alone treated group. Thus, ferulic acid contributes to the reversal of the MDR through suppression of P-gp expression via the inhibition of PI3K/Akt/NF-κB signaling pathway.