Human malignant melanoma is an aggressive skin cancer which has been rising at a greater rate than any other cancers. Although various new therapeutic methods have been developed in previous studies, this disease has properties of high proliferation and metastasis rate which remain obstacles that have lead to a poor prognosis in patients. It has been reported that a specific Lactobacillus extract has anti-cancer and –metastasis effect in vitro and in vivo. However, previous research has not specified precisely what effect the Lactobacillus rhamnosus GG (LGG) extract has had on human malignant melanomas. In this study, we showed that the LGG extract has anti-cancer and –metastasis effects on the human malignant melanoma cell lines, A375P and A375SM. At first, it was found that, while the LGG extract affects human neonatal dermal fibroblasts slightly, it induced the dose-dependent anti-cancer effect on A375P and A375SM by a WST-1 proliferation assay. As a result of a real-time PCR analysis, the expression patterns of several genes related to cell cycle, proliferation, and apoptosis were modulating in a manner that inhibited the growth of both malignant melanoma cell lines after the treatment of the LGG extract. Furthermore, genes related to the epithelialmesenchymal transition were down-regulated, and migration rates were also decreased significantly by the LGG extract. Our study showed that the LGG extract could be used as a potential therapeutic source.

L. rhamnosus GG 유산균은 1983년 건강한 성인의 장관에서 분리된 이래 인체의 수많은 건강효과에 관한 연구들이 진행되었다. 전세계의 연구자들이 이 프로바이오틱 유산균에 관심을 갖게 되었고, 인체에 대한 다양한 임상시험과 흥미로운 연구들이 진행되었다. 지난 20여 년간 프로바 이오틱 시장이 급격히 성장했음에도 불구하고, L. rhamnosus GG는 아직도 세계에서 가장 연구가 많이 진행된 유산균이다. 비록 in vitro와 실험적 연구들을 인체와 직접적으로 관련시킬 수는 없지만, 위의 연구들을 통해 L. rhamnosus GG가 장관에서 병원성 미생물을 억제하고, 이들이 혈관이나 세포조직으로 침투하는 것을 억제하며, 시스템적인 또는 국소적인 면역반응을 증강시키고, 감염 억제와 감염으로부터의 회복을 빠르게 하는 등의 역할을 하고 있음을 알 수 있다.