Poly-L-lysine (3~7W) is a positively charged synthetic polypeptide polymerized from L-lysine. Poly-L-lysine (3~7W) serves as a non-specific cell attachment factor, promoting cell adhesion to solid substrates by enhancing the electrostatic interaction between the negatively charged cell membrane and the culture surface (for cells capable of digesting poly-L-lysine, poly-D-lysine should be used as the attachment factor instead). Poly-L-lysine (3~7W) can be used as an encapsulating agent for drug formulation and nucleic acid delivery. Poly-L-lysine (3~7W) also exhibits activities that induce apoptosis and inhibit proliferation, thereby blocking tumorigenesis[1].
In vitro, Poly-L-lysine (3~7W) (0-25µg/mL; 24h) exhibited growth inhibitory effects against human cancer cell lines K562, A549, U937, and B16F10, with IC50 values of 3.36±0.16µM, 8.23±0.41µM, 3.53±0.17µM, and 6.04±0.3µM, respectively[2]. Poly-L-lysine (3~7W) (0.5-40µg/mL; 48h) inhibited the proliferation of MCF-7 cells in a dose-dependent manner, with an IC50 value of 4.22µg/mL[1]. Poly-L-lysine (3~7W) (0.5-30.0μg/mL; 24-72h) inhibited the proliferation of HUVEC and DAL cells in a dose- and time-dependent manner, and also altered the cell morphology of DAL cells[3]. Poly-L-lysine (3~7W) (10-120μg/mL; 2-4h) inhibited HeLa cell viability in a dose-dependent manner[4].
In vivo, Poly-L-lysine (3~7W) (20 and 40mg/kg; i.p.; 21 days) significantly reduced solid tumor volume and weight and prolonged survival in a dose-dependent manner in the S-180 solid tumor mouse model[2]. Poly-L-lysine (3~7W) (20-40mg/kg; i.p.; 21 days) significantly inhibited DAL-induced tumor formation in BALB/c mice, with solid tumor volume and weight markedly reduced compared to the control group[3].
References:
[1] Mukherjee A, Debnath S, Bhowmik A, Biswas S. DNA interactive property of poly-L-lysine induces apoptosis in MCF-7 cells through DNA interaction. J Biochem Mol Toxicol. 2023;37(8):e23378.
[2] Debnath S, Karan S, Debnath M, Dash J, Chatterjee TK. Poly-L-Lysine Inhibits Tumor Angiogenesis and Induces Apoptosis in Ehrlich Ascites Carcinoma and in Sarcoma S-180 Tumor. Asian Pac J Cancer Prev. 2017;18(8):2255-2268.
[3] Debnath S, Mukherjee A, Karan S, Debnath M, Chatterjee TK. Induction of apoptosis, anti-proliferation, tumor-angiogenic suppression and down-regulation of Dalton's Ascitic Lymphoma (DAL) induced tumorigenesis by poly-l-lysine: A mechanistic study. Biomed Pharmacother. 2018;102:1064-1076.
[4] Lin CW, et al. Protective role of autophagy in branched polyethylenimine (25K)- and poly(L-lysine) (30-70K)-induced cell death. Eur J Pharm Sci. 2012 Dec 18;47(5):865-74.
Experimental Protocol:
1. Prepare a 1mg/mL poly-lysine stock solution in sterile water, sterilize by filtration through a 0.22μm microporous filter, and store in aliquots at -20°C.
2. Dilute to 0.1mg/mL with sterile ultrapure water before use.
Note: It is recommended to use plastic containers and graduated cylinders when mixing or storing the solution and coating slides. Do not add fresh solution to used solution.
3. Equilibrate the diluted poly-lysine working solution to room temperature (18–26°C) before use.
4. Add the poly-lysine working solution to the culture vessel, gently rock to ensure even coverage, and incubate at room temperature for 5–10 minutes.
5. Aspirate the working solution, wash the culture vessel 1–2 times with PBS, and dry in an oven at 60°C for 1 hour or at room temperature (18–26°C) overnight.
Note: Poly-lysine is cytotoxic; the concentration of the coating solution may be reduced depending on specific experimental requirements.