Introduction: Cell proliferation, drug resistance, and invasion are the main reasons for the severity of metastatic Melanoma. The aforementioned features have been attained by the over activation of several signaling pathways such as Notch. Recent studies have shown that Notch suppression using γ-secretase inhibitors has an effective role in decreasing cancer properties.Materials and methods: In our study, we analyzed the primary effect of Notch pathway inhibition by
DAPT on A375(Melanoma metastatic cell line). In the in vitro phase of the study, the effect of Notch inhibition on self-renewal properties of the cells was assessed. Also, in order to investigate cells behavior, we applied several tests such as colony formation, sphere formation, cell migration, Notch1 and Nestin protein expression. Furthermore, the expression of Notch down-stream genes (Notch1, Hes1, Hes5) and
stemness genes (Oct4, Nanog, NESTIN) were examined by RT-PCR. In the in vivo model, every 72h, Notch inhibitor was injected via Intra tumoural(IT) and Intravenous(IV) to nude mice. Ki67, c-Myc, tumor cell death, and tumor pathology were measured after sacrificing the animals. What followed this, was designing a
mathematical model for each tumor.Results: we found the inhibitory effective dose of
DAPT by MTS test and measuring both the down-stream genes of Notch and Notch1 protein expression in A375 cell line. Our study showed, in short period of time
DAPT reduced migration and
stemness properties. however, an increase of
stemness property have observed after using
DAPT for long period. Xenograft and mathematical models demonstrated that some tumors had reduction in growth with IT and IV injections, on the other hand, some other showed drug resistancy. We realized, lower dosage of
DAPT as well as stop using it, lead
melanoma tumors to drug resistancy. following our observation, we offered an appropriate dose of
DAPT for the other tumors with the result that there were not any or bad effects, and all animals faced an effective cure.Conclusions: This results showed that
DAPT can be a unsafe choice in clinical stage for melanoma. because if the using dose of so-called treatment is not appropriate for cure, the drug resistancy and bad effects would appear. With
mathematical model we can establish the best reduction in tumor size and abolish the drug resistancy. In addition, we can use this method for other drugs in chemotherapy and increase the health condition of most patients.