Hypophyllanthin and Phyllanthin from Phyllanthus niruri Synergize Doxorubicin Anticancer Properties against Resistant Breast Cancer Cells

Doxorubicin (DOX) is a cornerstone chemotherapeutic agentfor the treatment of several malignancies such as breast cancer; however,its activity is ameliorated by the development of a resistant phenotype. Phyllanthus species have been studied previouslyfor their potential anticancer properties. The current work is aimedto study the potential cytotoxicity and chemomodulatory effects ofhypophyllanthin (PN4) and phyllanthin (PN5) isolated from Phyllanthus niruri to DOX against the adriamycin multidrug-resistant breast cancercells (MCF-7(ADR)) and elucidate their mechanism of action.The major compounds of the active methylene chloride fraction wereisolated and assessed for their potential cytotoxicity and chemomodulatoryeffects on DOX against nai''ve (MCF-7) and resistant breast (MCF-7(ADR)) cancer cells. The mechanism of action of both compoundsin terms of their impacts on programmed/non-programmed cell death(apoptosis and autophagy/necrosis), cell cycle progression/arrest,and tumor cell migration/invasion was investigated. Both compounds PN4 and PN5 showed a moderate but similar potencyagainst MCF-7 as well as MCF-7(ADR) and significantly synergizedDOX-induced anticancer properties against MCF-7(ADR). Thechemomodulatory effect of both compounds to DOX was found to be viapotentiating DOX-induced cell cycle interference and apoptosis induction.It was found that PN4 and PN5 blocked theapoptosis-escape autophagy pathway in MCF-7(ADR). On themolecular level, both compounds interfered with SIRT1 expression andconsequently suppressed Akt phosphorylation, and PN5 blockedapoptosis escape. Furthermore, PN4 and PN5 showed promising antimigratory and anti-invasive effects againstMCF-7(ADR), as confirmed by suppression of N-cadherin/& beta;-cateninexpression. In conclusion, for the first time, hypophyllanthin andphyllanthin isolated from P. niruri showed promising chemomodulatory effects to the DOX-induced chemotherapeuticactivity against MCF-7(ADR). Both compounds significantlysynergized DOX-induced anticancer properties against MCF-7(ADR). This enhanced activity was explained by further promoting DOX-inducedapoptosis and suppressing the apoptosis-escape autophagy feature ofthe resistant breast cancer cells. Both compounds (hypophyllanthinand phyllanthin) interfered with the SIRT1/Akt pathway and suppressedthe N-cadherin/& beta;-catenin axis, confirming the observed antiproliferative,cytotoxic, and anti-invasive effects of hypophyllanthin and phyllanthin.

Automated summary

This study aimed to investigate the cytotoxicity and chemomodulatory effects of PN4 and PN5 isolated from Phyllanthus niruri on adriamycin multidrug-resistant breast cancer cells (MCF-7(ADR)) and elucidate their mechanism of action. The results showed that both compounds exhibited moderate potency against MCF-7 and MCF-7(ADR), and significantly synergized the anticancer properties of DOX. The chemomodulatory effect of both compounds was achieved through promoting DOX-induced cell cycle interference and apoptosis induction.