Marine Cyclic Dipeptide Cyclo (L-Leu-L-Pro) Protects Normal Breast Epithelial Cells from tBHP-induced Oxidative Damage by Targeting CD۱۵۱

Background: Oxidative stress plays a key role in breast carcinogenesis. Cyclo(L-Leu-L-Pro) (CLP) is a homodetic cyclic dipeptide with ۲,۵-diketopiperazinescaffold isolated from marine actinobacteria. This study aimed to evaluate theprotective activity of CLP and linear - (L-Leu-L-Pro) (LP) from tert-butylhydroperoxide (tBHP)-induced damage using normal breast epithelial cell linemodel (MCF-۱۲A).Methods: The cytoprotective activity was evaluated by detecting the changesin intracellular ROS, mitochondrial superoxide, hydroxyl radical, hydrogenperoxide, and lipid peroxidation detection assays as well as cytotoxic assays ofMTT, LDH assays and phase contrast microscopy. Genoprotective activity wasevaluated by (Apurinic/Apyrimidinic) AP site, alkaline Comet, and ۸-hydroxy-۲-deoxyguanosine assays.Results: The marine cyclic peptide, CLP, significantly protected MCF-۱۲Acells by scavenging tBHP induced intracellular ROS such as super oxide, hydroxylradicals and hydrogen peroxide, and by reducing the cytotoxicity and genotoxicityeffect compared to LP. Moreover, the results showed that CD۱۵۱ gene silencing byshRNA significantly reduced the overexpression of CD۱۵۱, tBHP-induced ROSgeneration, cytotoxicity and genotoxicity in MCF-۱۲A cells. The overexpressionof CD۱۵۱ caused increased levels of cytochrome P۴۵۰, but was reduced followingthe application of CD۱۵۱shRNA and CLP which led to elevated levels ofintracellular ROS.Conclusion: In the present study we noticed that CD۱۵۱ gene silencing byshRNA and treatment with CLP have similar effects on reducing the intracellularROS. This study uncovers the protective activity of CLP against a CD۱۵۱-mediated oxidative stress-induced cellular damage. Our observations suggest thatthe anti-stress and anti-inflammation properties of CLP might have implications incancer and are worth testing in cancer cell lines and tumor cells.

Keywords:

Actinobacteria , apoptosis , cytoprotective , DNA damage , MCF-۱۲A cells