Role Of NOTCH Pathway In Targeted Therapy Against The Esophageal Cancer StemCells

Esophageal cancer is the 6th leading cancer related deaths in the world. It is divided to twosubtypes histologically: Esophageal squamous cell and Adeno carcinoma. Squamous type involvesmore than 90% of Asian cases. It has been shown that the survival in ESCC cases is 10% lower thanthat in the patients with adeno carcinoma. Cancer stem cells (CSCs) are the main reason of tumorrelapse in ESCC patients. These cells have stem cell characteristics and are resistant toward thecommon chemo radio therapeutic treatments. Regarding the importance of NOTCH pathway inpreservation of CSCs, it can be possible to target such cells via the NOTCH pathway. In the presentstudy we isolated the CD44+ ESCC CSCs and designed a targeted therapy against them via thetargeting MAML1 as the main transcription factor of NOTCH signaling pathway. Isolation of CSCswas performed using the magnetic cell sorting (MACS) based on CD44 cell surface marker. Theisolated CD44+-CSCs were characterized using the molecular technics in the levels of protein andmRNA expression (Real time PCR, IHC, ICC, and WB). Moreover, the isolated cells werecharacterized in-vivo by NUDE mice injection. Role of MAML1 and NOTCH pathway was assessed inbiology of isolated CSC-CD44+ via the MAML1 ectopic expression and silencing by the cellular andmolecular technics such as real time PCR, scratch assay, MTT assay, and cell cycle analysis. Finally,drug resistance assay also perform to assess the role of NOTCH pathway in 5FU resistance of CSCs-CD44+. The present study has shown that, the CSC-CD44+ has ability to form sphere in specificmedium and form tumor in NUDE mice. MAML1 silencing resulted in a significant decrease in cellmigration (p=0.019) and MAML1 ectopic expression resulted in a significant increase in migrationof CSCs-CD44+ (p=0.012). Moreover, MAML1 silencing and ectopic expression caused a significantincrease and decrease in 5FU resistance, respectively (p<0.05). MAML1 silencing resulted in asignificant increase in numbers of G1 cells (p=0.008) and its ectopic expression significantlyincreased numbers of CSC-CD44+ in S phase (p=0.037). Moreover, we showed that the ABCG2 has themain role in resistance of CD44+ cancer stem cells against the 5FU. Regarding the present study theNOTCH pathway has an important role in preservation of CSC-CD44+ and their drug resistance.Therefore, NOTCH pathway can be used as an efficient targeted therapy in elimination of CSC-CD44+in ESCC patients with the lowest side effects.C