Low-temperature plasma-activated Ringer's lactate solution induces apoptosis in melanoma cells by downregulating heat shock proteins and by inducing mitochondrial dysfunction.

BACKGROUND

Low-temperature plasma (LTP) is an essential technology in engineering that originated in materials science. Its applications have recently been expanded to biology, where it is referred to as plasma biology. LTP and LTP-activated solutions are now used for wound healing and sterilization. One emerging field is cancer treatment.

OBJECTIVE

To evaluate the effectiveness of LTP-activated Ringer's lactate solution (PAL) against malignant melanoma.

METHODS

Cells of the A375 malignant melanoma line were subcutaneously injected into nude mice. PAL was administered three times weekly, and tumor growth was measured. Cell viability was measured using MTS assay in vitro experiments. Whole transcriptome sequencing and qRT-PCR were conducted to reveal differentially expressed mRNAs. To detect DNA double-strand breaks, immunofluorescence of γ-H2AX foci was performed. Mitochondrial membrane potential and apoptosis were detected by JC-1 probe and caspase-3/7 detection reagents, respectively.

RESULTS

The PAL exhibited an anti-cancer effect in the A375 xenograft mouse model. The PAL also showed in vitro cytotoxicity for a melanoma cell line. Comprehensive RNA expression analysis revealed the downregulation of multiple heat shock proteins (HSPs), especially HSPA1A, HSPA1B, HSPA6, HSPA7 and DNAJB1. HSP insufficiency induced lower mitochondrial membrane potential. The mode of cell death for the melanoma cells was apoptosis.

CONCLUSION

PAL is suggested as a promising new therapeutic agent for malignant melanoma.