DNA Repair Biosensor-Identified DNA Damage Activities of Endophyte Extracts from Garcinia cowa.

Tassanee Lerksuthirat,Sermsiri Chitphuk,Somponnat Sampattavanich,Siwanon Jirawatnotai,Rakkreat Wikiniyadhanee,Donniphat Dejsuphong,Wasana Stitchantrakul,Juangjun Jumpathong

doi:10.3390/biom10121680

Tassanee Lerksuthirat, Sermsiri Chitphuk + Show 6 more

Open Access

https://doi.org/10.3390/biom10121680

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Abstract

Recent developments in chemotherapy focus on target-specific mechanisms, which occur only in cancer cells and minimize the effects on normal cells. DNA damage and repair pathways are a promising target in the treatment of cancer. In order to identify novel compounds targeting DNA repair pathways, two key proteins, 53BP1 and RAD54L, were tagged with fluorescent proteins as indicators for two major double strand break (DSB) repair pathways: non-homologous end-joining (NHEJ) and homologous recombination (HR). The engineered biosensor cells exhibited the same DNA repair properties as the wild type. The biosensor cells were further used to investigate the DNA repair activities of natural biological compounds. An extract from Phyllosticta sp., the endophyte isolated from the medicinal plant Garcinia cowa Roxb. ex Choisy, was tested. The results showed that the crude extract induced DSB, as demonstrated by the increase in the DNA DSB marker γH2AX. The damaged DNA appeared to be repaired through NHEJ, as the 53BP1 focus formation in the treated fraction was higher than in the control group. In conclusion, DNA repair-based biosensors are useful for the preliminary screening of crude extracts and biological compounds for the identification of potential targeted therapeutic drugs.

Highlights

It is well known that conventional chemotherapy relies on inhibiting cell proliferation
We further explored whether the crude extracts affected the downstream level of non-homologous end-joining (NHEJ), since 53BP1 is the initial player in the NHEJ pathway
We constructed a biosensor based on the double strand break (DSB) repair pathways to investigate the bioactivity, with particular focus on DNA damage and repair, of crude extracts from the medicinal plant Garcinia cowa and its endophyte Phyllosticta sp

Summary

Introduction

It is well known that conventional chemotherapy relies on inhibiting cell proliferation. This mode of action can target cancer cells, the side effects are frequently intolerable and treatment is not optimally effective in all patients [1]. Targeting DNA double strand break (DSB) repair pathways has proved to be effective in cancer treatments [3,4]. Two major DNA DSB repair pathways are homologous recombination (HR) and non-homologous end-joining (NHEJ). Olaparib is the well-known example of targeted drugs to treat ovarian or breast cancer patients with BRCA germline mutations [5]. Current models for drug development are limited in terms of the identification and targeting of DNA repair activity

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