Biodegradable Eri silk nanoparticles as a delivery vehicle for bovine lactoferrin against MDA-MB-231 and MCF-7 breast cancer cells

Abstract

This study used the Eri silk nanoparticles (NPs) for delivering apo-bovine lactoferrin (Apo-bLf) (~2% iron saturated) and Fe-bLf (100% iron saturated) in MDA-MB-231 and MCF-7 breast cancer cell lines. Apo-bLf and Fe-bLf-loaded Eri silk NPs with sizes between 200 and 300 nm (±10 nm) showed a significant internalization within 4 hours in MDA-MB-231 cells when compared to MCF-7 cells. The ex vivo loop assay with chitosan-coated Fe-bLf-loaded silk NPs was able to substantiate its future use in oral administration and showed the maximum absorption within 24 hours by ileum. Both Apo-bLf and Fe-bLf induced increase in expression of low-density lipoprotein receptor-related protein 1 and lactoferrin receptor in epidermal growth factor (EGFR)-positive MDA-MB-231 cells, while transferrin receptor (TfR) and TfR2 in MCF-7 cells facilitated the receptor-mediated endocytosis of NPs. Controlled and sustained release of both bLf from silk NPs was shown to induce more cancer-specific cytotoxicity in MDA-MB-231 and MCF-7 cells compared to normal MCF-10A cells. Due to higher degree of internalization, the extent of cytotoxicity and apoptosis was significantly higher in MDA-MB-231 (EGFR+) cells when compared to MCF-7 (EGFR−) cells. The expression of a prominent anticancer target, survivin, was found to be downregulated at both gene and protein levels. Taken together, all the observations suggest the potential use of Eri silk NPs as a delivery vehicle for an anti-cancer milk protein, and indicate bLf for the treatment of breast cancer.

Silk Particles as Carriers of Therapeutic Molecules for Cancer Treatment

“…An example of such protein is lactoferrin. Bovine lactoferrin and its variants with different iron saturation levels (e.g., apo-bovine lactoferrin that is~2% Fe saturated) were cytotoxic towards breast cancer MDA-MB-231 and MCF-7 cells in the in vitro studies [120]. In contrast, no such activity was reported towards control, non-cancer MCF-10-2A cells.…”

“…The lactoferrin-loaded silk particles showed significantly higher internalization into the MDA-MB-231 and MCF-7 cells than the unloaded silk particles, whereas the apo-bovine lactoferrin showed significantly higher internalization only into the MCF-7 breast cancer cells. Also, both lactoferrin and apo-bovine lactoferrin loaded spheres induced cytotoxicity towards the tested cell lines in the in vitro studies, activating different apoptotic pathways depending on the EGFR status of the tested cell line [120].…”

“…The particles were obtained through chopping, milling, and spray drying of the degummed Eri cocoons. The obtained particles showed round morphology with the diameter ranging from 150 to 250 nm (before the loading of lactoferrin) and 200 to 300 nm after the loading of lactoferrin [120]. The lactoferrin-loaded silk particles showed significantly higher internalization into the MDA-MB-231 and MCF-7 cells than the unloaded silk particles, whereas the apo-bovine lactoferrin showed significantly higher internalization only into the MCF-7 breast cancer cells.…”

“…The particle-like silk carriers can also bind and deliver peptides and proteins (e.g., enzymes, cytokines) [77,[116][117][118][119][120][121]. The encapsulation of enzymes in the carriers may prolong their in vivo stability and help preserve their enzymatic activity over time.…”

Lactoferrin: A Glycoprotein Involved in Immunomodulation, Anticancer, and Antimicrobial Processes

“…On the other hand, it is known that many cancer cells have a high content of proteoglycan, glycosaminoglycan and sialic acid, which are known to interact with Lf, which probably activates other signaling pathways to generate harmful effects to cells [ 66 ]. This possible mechanism will also explain the high cytotoxic selectivity that Lf has on cancer cells and not on healthy cells [ 65 , 67 , 68 , 69 , 70 ]. Despite the fact that various authors showed that Lf has high selective cytotoxicity, not all reported the selective cytotoxicity index (SCI), which gives the ability of a compound to kill cancer cells with minimal toxicity to non-cancer cells.…”