Novel bioactive cationic cubosomes enhance the cytotoxic effect of paclitaxel against a paclitaxel resistant prostate cancer cell-line.

Hypothesis The study aimed to use molecular hybridization of a cationic lipid with a known pharmacophore to produce a bifunctional lipid having a cationic charge to enhance fusion with the cancer cell surface and biological activity via the pharmacophoric head group. Experiments The novel cationic lipid DMP12 [N-(2-(3-(3,4-dimethoxyphenyl) propanamido) ethyl)-N-dodecyl-N-methyldodecan-1-aminium iodide] was synthesised by conjugating 3-(3,4-dimethoxyphenyl) propanoic acid (or 3,4-dimethoxyhydrocinnamic acid) to twin 12 carbon chains bearing a quaternary ammonium group [N-(2-aminoethyl)-N-dodecyl-N-methyldodecan-1-aminium iodide]. The physicochemical and biological properties of DMP12 were investigated. Cubosome particles consisting of monoolein (MO) doped with DMP12 and paclitaxel were characterized using Small-angle X-ray Scattering (SAXS), Dynamic Light Scattering (DLS), and Cryo-Transmission Electron Microscopy (Cryo-TEM). Combination therapy using these cubosomes was assessed in vitro against the gastric (AGS) and prostate (DU-145 and PC-3) cancer cell lines using cytotoxicity assay. Findings Monoolein (MO) cubosomes doped with DMP12 were observed to be toxic against the AGS and DU-145 cell-lines at higher cubosome concentrations (≥100 µg/ml) but had limited activity against the PC-3 cell-line. However, combination therapy consisting of 5 mol% DMP12 and 0.5 mol% paclitaxel (PTX) significantly increased the cytotoxicity against the PC-3 cell-line which was resistant to either DMP12 or PTX individually. The results demonstrate that DMP12 has a prospective role as a bioactive excipient in cancer therapy.

A lipid-modified estrogen derivative that treats breast cancer independent of estrogen receptor expression through simultaneous induction of autophagy and apoptosis.

It is a challenge to develop a universal single drug that can treat breast cancer at single- or multiple-stage complications, yet remains nontoxic to normal cells. The challenge is even greater when breast cancer-specific, estrogen-based drugs are being developed that cannot act against multistaged breast cancer complications owing to the cells differential estrogen receptor (ER) expression status and their possession of drug-resistant and metastatic phenotypes. We report here the development of a first cationic lipid-conjugated estrogenic derivative (ESC8) that kills breast cancer cells independent of their ER expression status. This ESC8 molecule apparently is nontoxic to normal breast epithelial cells, as well as to other noncancer cells. ESC8 induces apoptosis through an intrinsic pathway in ER-negative MDA-MB-231 cells. In addition, ESC8 treatment induces autophagy in these cells by interfering with the mTOR activity. This is the first example of an estrogen structure-based molecule that coinduces apoptosis and autophagy in breast cancer cells. Further in vivo study confirms the role of this molecule in tumor regression. Together, our results open new perspective of breast cancer chemotherapy through a single agent, which could provide the therapeutic benefit across all stages of breast cancer.

17ß-estradiol-linked nitro-L-arginine as simultaneous inducer of apoptosis in melanoma and tumor-angiogenic vascular endothelial cells.

Aggressive melanoma is commonly associated with rapid angiogenic growth in tumor mass, tumor cells acquiring apoptosis resistance, inhibition of cellular differentiation etc. Designing a single anticancer molecule which will target all these factors simultaneously is challenging. In the pretext of inciting anticancer effect through inhibiting nitric oxide synthase (NOS) via estrogen receptors (ER) in ER-expressing skin cancer cells, we developed an estrogen-linked L-nitro-arginine molecule (ESAr) for inciting anticancer effect in melanoma cells. ESAr showed specific anticancer effect through diminishing aggressiveness and metastatic behavior in melanoma cells and tumor. In comparison, ESAr showed significantly higher antiproliferative effect than parent molecule L-nitroarginine methyl ester (L-NAME, a NOS inhibitor) through induction of prominent apoptosis in melanoma cells. ESAr-pretreated aggressive melanoma cells could not form tumor possibly because of transformation/differentiation into epithelial-type cells. Furthermore, its antiangiogenic effect was demonstrated through ESAr-induced antiproliferation in HUVEC cells and apoptosis-induction in tumor-associated vascular endothelial cells, thereby significantly restricting severe growth in melanoma tumor. The targeting moiety, estrogen, at the therapeutic concentration of ESAr has apparently no effect in tumor-growth reduction. Albeit, no specific NOS-inhibition was observed, but ESAr could simultaneously induce these three cancer-specific antiaggressiveness factors, which the parent molecule could not induce. Our data rationalize and establish a new use of estrogen as a ligand for potentially targeting multiple cellular factors for treating aggressive cancers.

Histidylated lipid-modified Sendai viral envelopes mediate enhanced membrane fusion and potentiate targeted gene delivery.

Recent studies have demonstrated that covalent grafting of a single histidine residue into a twin-chain aliphatic hydrocarbon compound enhances its endosome-disrupting properties and thereby generates an excellent DNA transfection system. Significant increase in gene delivery efficiencies has thus been obtained by using endosome-disrupting multiple histidine functionalities in the molecular architecture of various cationic polymers. To take advantage of this unique feature, we have incorporated L-histidine (N,N-di-n-hexadecylamine) ethylamide (L(H)) in the membrane of hepatocyte-specific Sendai virosomes containing only the fusion protein (F-virosomes (Process for Producing a Targeted Gene (Sarkar, D. P., Ramani, K., Bora, R. S., Kumar, M., and Tyagi, S. K. (November 4, 1997) U. S. Patent 5,683,866))). Such L(H)-modified virosomal envelopes were four times more (p < 0.001) active in terms of fusion with its target cell membrane. On the other hand, the presence of L(H) in reconstituted influenza and vesicular stomatitis virus envelopes failed to enhance spike glycoprotein-induced membrane fusion with host cell membrane. Circular dichroism and limited proteolysis experiments with F-virosomes indicated that the presence of L(H) leads to conformational changes in the F protein. The molecular mechanism associated with the increased membrane fusion induced by L(H) has been addressed in the light of fusion-competent conformational change in F protein. Such enhancement of fusion resulted in a highly efficient gene delivery system specific for liver cells in culture and in whole animals.