Anti-breast cancer effects of Enterococcus faecium MBT05

다국어 초록 (Multilingual Abstract)

Triple-negative breast cancer (TNBC), a specific subtype of breast cancer that does not express estrogen receptor (ER), progesterone receptor (PR), or human epidermal growth factor receptor 2 (HER2), has clinical features that include high invasiveness, high metastatic potential, propensity to relapse, and poor prognosis. Because TNBC tumors lack ER, PR, and HER2 expression, they are not sensitive to endocrine therapy or HER2 treatment, and standardized TNBC treatment regimens are lacking. Therefore, development of new TNBC treatment strategies has become an urgent clinical need.
Microorganisms have advantages, challenges, and novel functions for tumor therapy, and combinations of bacteria with conventional compounds can be applied with high therapeutic potential. We identified Enterococcus faecium MBT05 as a microorganism that showed the highest cytotoxicity to MDA-MB-231 and MCF-7 cells and isolated its active ingredient, 5-oxo-2-pyrrolidinepropanoic acid, which induced apoptosis, as demonstrated by cleavage of PARP and increase of phosphorylated p53. The compound 5-oxo-2-pyrrolidinepropanoic acid blocks the Raf/Erk pathway by inhibiting phosphorylation of epidermal growth factor receptor (EGFR), which is overexpressed in triple-negative breast cancer (TNBC).
Additionally, Enterococcus faecium MBT05 and 5-oxo-2-pyrrolidinepropanoic acid inhibited estrogen receptor α (ERα) and estrogen receptor β (ERβ), which are overexpressed in luminal A type disease.
These findings suggest the potential of 5-oxo-2-pyrrolidinepropanoic acid as an anti-tumor therapeutic agent for TNBC and luminal A that functions by targeting EGFR and inhibiting ERα and ERβ.

목차 (Table of Contents)

• Ⅰ. Introduction 1
• Ⅱ. Materials and Methods 4
• Reagents and antibodies 4
• Microorganism culture 4
• Cell lines and culture 5
• Cell viability assay 5
• Identification of microorganisms 6
• Western blot analysis 6
• Quantitative real-time PCR 7
• NMR and GC/MS analysis 9
• Isolation and structural elucidation of active components from E. faecium 10
• In vivo hollow fiber assay 11
• Statistical analysis 12
• Ⅲ. Results 13
• Screening of microorganisms with cytotoxic effect on breast cancer cells 13
• Isolation and identification of microorganism strains with cytotoxic effects on breast cancer cells 19
• Inhibition of overexpressed genes in the TNBC cell line MDA-MB-231 by CFS of E. faecium MBT05 22
• CFS of E. faecium MBT05 regulates the EGFR/Raf/Erk signaling pathway in MDA-MB-231 cells 25
• CFS of E. faecium MBT05 regulates PARP and caspase-9 in MDA-MB-231 cells 28
• CFS of E. faecium MBT05 regulates the ERα/ERβ signaling pathway in MCF-7 cells 30
• Isolation of anti-tumorigenic compounds from the CFS of E. faecium MBT05 33
• Cytotoxic effect of 5-oxo-2-pyrrolidinepropanoic acid on breast cancer cells 38
• 5-oxo-2-pyrrolidinepropanoic acid suppressed the EGFR/Raf/Erk pathway in MDA-MB-231 cells 40
• Inhibition of overexpressed genes in MCF-7 by 5-oxo-2-pyrrolidinepropanoic acid 43
• 5-oxo-2-pyrrolidinepropanoic acid suppressed the ERα/ERβ pathway in MCF-7 cells 46
• 5-oxo-2-pyrrolidinepropanoic acid with EGF did not inhibit ERα/ERβ in MCF-7 cells 49
• Evaluation of the MDA-MB-231 HFA model with E. faecium in-vivo 51
• Ⅳ. Discussion 53
• References 58
• Abstract in Korean 63