Synthesis and anti-OXPHOS, antitumor activities of DLC modified spinosyn derivatives

A series of DLC (delocalized lipophilic cation) modified spinosyn derivatives were synthesized and evaluated for antitumor efficacies both in vitro and in vivo. Cancer cell based antiproliferative assays indicated that the more lipophilic derivatives had stronger inhibitory effects on the tested cancer cell lines. Compound 7b and 8b exhibited strong anti-OXPHOS and apoptosis inducing ability. Notable antitumor efficacies of 7b (5 mg/kg) and 8b (2.5 mg/kg) were observed in the in vivo tumor xenograft experiments, however, lethal toxicities were observed on higher dosages. Our findings indicated that DLC modification is a viable strategy to enhance the anti-OXPHOS and antitumor efficacies of spinosyn derivatives.

A novel delocalized lipophilic cation-chlorambucil conjugate inhibits P-glycoprotein in HepG2/ADM cells

Multidrug resistance (MDR) limits the application of a large number of cancer-fighting agents in clinical therapy. One reason is that P-glycoprotein (Pgp) efflux pumps are usually overexpressed and lead to drug efflux in the cancer cells, which limits the viability of many chemotherapeutics. Current available inhibitors which block the Pgp pump efflux are usually not widely used in clinical practice, because they change other drug pharmacokinetic profiles or increase side effects. Here, through covalent linkage of cancer-targeting delocalized lipophilic cation FF and DNA-damaging drug nitrogen mustard chlorambucil (CLB), we rationally designed and synthesized a tumor-targeting anticancer agent FFCLB. And we found and proved that the FFCLB was capable of reducing the outflow of Pgp substrates efficiently. This conjugate selectively improves adriamycin uptake and toxicity through reducing MDR1 mRNA and Pgp protein expression. Based on molecular targeted strategy, this study can facilitate the discovery of superior MDR reducing agents to provide a more effective and safer way of resensitizing MDR.

Derivatives of alkyl gallate triphenylphosphonium exhibit antitumor activity in a syngeneic murine model of mammary adenocarcinoma

We previously demonstrated that alkyl gallates coupled to triphenylphosphine have a selective and efficient antiproliferative effect by inducing mitochondrial uncoupling in vitro due to the increased mitochondrial transmembrane potential of tumor cells. Therefore, in this work, the in vivo antitumor activities of alkyl gallate triphenylphosphonium derivatives (TPP⁺C₈, TPP⁺C₁₀ and TPP⁺C₁₂) were evaluated in a syngeneic murine model of breast cancer. We found that TPP⁺C₁₀ increased the cytosolic ADP/ATP ratio and significantly increased the AMP levels in a concentration-dependent manner in TA3/Ha murine mammary adenocarcinoma cells. Interestingly, TPP⁺C₁₀ induced a decrease in the levels of cellular proliferation markers and promoted caspase-3 activation in tumor-bearing mice. Additionally, TPP⁺C₁₀ inhibited tumor growth in the syngeneic mouse model. Importantly, 30days of intraperitoneal (i.p.) administration of the combination of TPP⁺C₁₀ (10mg/kg/48h) and the antibiotic doxycycline (10mg/kg/24h) completely eliminated the subcutaneous tumor burden in mice (n=6), without any relapses at 60days post-treatment. This enhancement of the individual activities of TPP⁺C₁₀ and doxycycline is due to the uncoupling of oxidative phosphorylation by TPP⁺C₁₀ and the inhibition of mitochondrial biogenesis by doxycycline, as demonstrated by loss of mitochondrial mass and overexpression of PGC1-α as an adaptive response. Moreover, i.p. administration of TPP⁺C₁₀ (10mg/kg/24h) to healthy mice did not produce toxicity or damage in organs important for drug metabolism and excretion, as indicated by hematological, biochemical and histological assessments. These findings suggest that the combination of TPP⁺C₁₀ with doxycycline is a valuable candidate therapy for breast cancer management.