A multivariate statistical analysis of the effects of styrene maleic acid encapsulated RL71 in a xenograft model of triple negative breast cancer.

We have previously shown that the curcumin derivative 3,5-bis(3,4,5-trimethoxybenzylidene)-1-methylpiperidine-4-one (RL71), when encapsulated in styrene maleic acid micelles (SMA-RL71), significantly suppressed the growth of MDA-MB-231 xenografts by 67%. Univariate statistical analysis showed that pEGFR/EGFR, pAkt/Akt, pmTOR/mTOR and p4EBP1/4EPBP1 were all significantly decreased in tumors from treated mice compared to SMA controls. In this study, multivariate statistical analyses (MVAs) were performed to identify the molecular networks that worked together to drive tumor suppression, with the aim to determine if this analysis could also be used to predict treatment outcome. Linear discriminant analysis correctly predicted, to 100% certainty, mice that received SMA-RL71 treatment. Additionally, results from multiple linear regression showed that the expression of Ki67, PKC-α, PP2AA-α, PP2AA-ß and CaD1 networked together to drive tumor growth suppression. Overall, the MVAs provided evidence for a molecular network of signaling proteins that drives tumor suppression in response to SMA-RL71 treatment, which should be explored further in animal studies of cancer.

Periplocymarin is a potential natural compound for drug development: highly permeable with absence of P-glycoprotein efflux and cytochrome P450 inhibitions.

Periplocymarin, a cardiac glycoside isolated from Periploca sepium (P. sepium) and Periploca graeca (P. graeca), is a potential anti-cancer compound. The aim of the study was to investigate the potential for periplocymarin to interact with P-glycoprotein (P-gp) and to inhibit cytochrome P450s known to be expressed in the human small intestine. The in vitro and in situ permeability of periplocymarin were studied using Madin-Darby canine kidney (MDCK-II-WT) cells transfected with or without the human multidrug resistance (MDR1) gene and the single-pass perfused rat intestinal model. The cell system exhibited high functional activity and a net efflux ratio (NER) of 4.32 after transport of Rhodamine 123 (R123) (the P-gp substrate). Periplocymarin is highly permeable (Papp > 10 × 10(-6) cm/s; Peff(rat) > 5.09 × 10(-5) cm/s) and independent of P-gp influences. The NER at 100 µm periplocymarin (0.8) was unchanged in the presence of cyclosporine A (a non-specific P-gp inhibitor) (0.82). In the single-pass intestinal model, the Peff (rat) of 5 µg/ml periplocymarin (5.490 × 10(-5) cm/s) did not change in the presence of cyclosporine A (5.394 × 10(-5) cm/s). In the R123-inhibition assay, periplocymarin did not competitively inhibit P-gp. The inhibitory potential of periplocymarin on cytochrome P450 (CYP450s) was also studied. Periplocymarin (5, 50 µm) did not inhibit CYP1A2, CYP2C9, CYP2C19, CYP2D6 or CYP3A4. Thus, periplocymarin is unlikely to encounter drug-drug interactions with P-gp and CYP450s. Periplocymarin could be taken forward for further studies in drug development to test bioavailability, Phase II enzyme interactions and additional transporter interactions.