Pu-erh Tea Inhibits Tumor Cell Growth by Down-Regulating Mutant p53

Lanjun Zhao,Shuting Jia,Ying Luo,Wenru Tang,Jun Sheng

doi:10.3390/ijms12117581

Abstract

Pu-erh tea is a kind of fermented tea with the incorporation of microorganisms’ metabolites. Unlike green tea, the chemical characteristics and bioactivities of Pu-erh tea are still not well understood. Using water extracts of Pu-erh tea, we analyzed the tumor cell growth inhibition activities on several genetically engineered mouse tumor cell lines. We found that at the concentration that did not affect wild type mouse embryo fibroblasts (MEFs) growth, Pu-erh tea extracts could inhibit tumor cell growth by down-regulated S phase and cause G1 or G2 arrest. Further study showed that Pu-erh tea extracts down-regulated the expression of mutant p53 in tumor cells at the protein level as well as mRNA level. The same concentration of Pu-erh tea solution did not cause p53 stabilization or activation of its downstream pathways in wild type cells. We also found that Pu-erh tea treatment could slightly down-regulate both HSP70 and HSP90 protein levels in tumor cells. These data revealed the action of Pu-erh tea on tumor cells and provided the possible mechanism for Pu-erh tea action, which explained its selectivity in inhibiting tumor cells without affecting wild type cells. Our data sheds light on the application of Pu-erh tea as an anti-tumor agent with low side effects.

Highlights

Pu-erh tea is produced in the Yunnan province of China
We found that 0.25 mg/mL of water extracts of green tea, black tea or Pu-erh tea have similar activity in inhibiting the growth of tumor cells SCID-3B-1 (Figure 1A)
The results showed that different batches of Pu-erh tea had very similar activity in tumor cell growth inhibition (Figure 1B, SCID22-3B-1), and the concentration we used (0.25 mg/mL) did not inhibit the growth of wild type cells (Figure 1B, wild type)

Summary

Introduction

The key process of Pu-erh preparation includes the step of fermentation, in which microorganisms play a very important role in producing the taste, color, fragrances, as well as the functional components. It is believed in Chinese tradition that the taste, as well as the function of Pu-erh tea gets better with increasing shelf time, mainly because the fermentation process is still ongoing during storage. This leads to a very interesting hypothesis, that the bioactivity components of Pu-erh tea are produced during the fermentation process

Results

Discussion

Conclusion