Turn-folded magainin lipopeptide analog induces cytoplasmic vacuoles in MDA-MB-231 cells through G2-phase arrest

Endocytosis Involved d-Oligopeptide of Tryptophan and Arginine Displays Ordered Nanostructures and Cancer Cell Stereoselective Toxicity by Autophagy

“…The surface of the treated cell was distorted from the normal spindle and grooved morphology and covered with unusual protruding masses that likely originated from the intracellular matrix. It appears that allD HHC36 triggered the extensive formation of cytoplasmic vacuoles in the MDA-MB-231 cell similar to paraptotic death . Compared with the control, the treated cell was shrunk, and the outer membrane surface lost its morphology (cf.…”

“…Accordingly, it seems that the effectiveness of allD HHC36 and retroinverso HHC36 is dependent on the cell type. Even though the d -peptides are less efficient than doxorubicin (DOX) against the lung and breast cell lines (IC 50 ≈ 1.0–5.0 μg/mL), , they have shown higher selectivity than the generic chemotherapeutic drug, given their impacts on the HUVEC viability (IC 50 ≈ 220–270 μM at 24 h).…”

“…The lung and breast cancer cells in the growth medium were incubated in the six flat-bottom well plates at a density of 500,000 ( T = 37 °C, t = 24 h). Next, the cells were treated with 6-FAM-labeled HHC peptides (i.e., HHC36, allD HHC36, and retroinverso HHC36) at 15 μM and/or 45 μM for various time incubation ranging from 15 min to 3 h. If required, the cells were 30 min preincubated with 10 mM NaN 3 /6 mM 2-DG, 5 mM MβCD, and 80 mM NaClO 3 endocytosis inhibitors that, respectively, disrupt the cellular ATP supply, sequesters the plasma membrane CHO, and prevents the sulfation of HSPGs. , Also, the peptide-treated A549 cells (at c pep = 15 μM) were incubated at 4 °C for 1 h to evaluate the effect of temperature on the membrane uptake. Next, the cells were washed with PBS twice, treated with trypsin–EDTA solution 2×, and pelleted at 8,500 g for 10 min.…”

“…In a step-by-step protocol, the cells pellets were postfixed with 1% OsO 4 at r.t. for 1 h, washed with the CAC buffer, solidified in agarose (1–1.5%), cut into fine pieces, dehydrated with a series of 25, 50, 70, 90, and 100% ethanol and rinsed with propylene oxide thrice. ,, In the next steps, the samples were immersed in 25, 50, 75, and 100% epoxy resin mixtures for as long as necessary, ,, transferred to casting blocks, and dried at 60 °C for a few days. The blocks were sliced into sections of <120 nm thick, placed on the copper grids, counterstained with 3% uranyl acetate and 2% lead citrate for a few minutes, and finally washed with water and prepared for imaging using a TEM (ZEISS-EM10C-100 kV, Germany).…”

“…Owing to the failure of current chemotherapeutic mechanisms and their associated health risks, hopes were given up with regard to the treatment of resistant cancer cells . The amphipathic anticancer peptides (ACPs) that selectively target the cell survival signaling are potentially attractive for clinical use. − However, the hydrolytic instability of ACPs along with the altered composition of the cell membrane and defects in the apoptotic machinery may result in peptide ineffectiveness. , In this regard, the redox imbalance or impaired metabolic homeostasis induced by the in vitro self-assembling of ACPs and their accumulation in the endoplasmic reticulum (ER) or inside the mitochondria are considered suitable to treat the resistant cancer cells. ,, Alternatively, the caspase-independent necroptotic or autophagic deaths promoted by the ACP nanostructures via targeting the Golgi apparatus and ER membrane systems are privileged for the selective toxicity. − …”