title: Overexpression of CD133 enhances chemoresistance to 5-fluorouracil by activating the PI3K/Akt/p70S6K pathway in gastric cancer cells.
abstract: CD133 has been reported to be associated with chemoresistance in various cancer cells. The efficacy of 5-fluorouracil (5-FU), an important chemotherapeutic agent for advanced gastric cancer (GC), is limited by 5-FU resistance. Hence, the present study investigated the function of CD133 in 5-FU resistance in human GC cells. We isolated CD133+ GC cells by immunomagnetic cell sorting and CD133 expression was modulated by transfection of CD133 gene or CD133 small interfering ribonucleic acid. To assess the 5-FU cytotoxicity, Cell Counting Kit-8 was used. Expression of CD133, P-glycoprotein (P-gp), B-cell lymphoma 2 (Bcl‑2), Bcl-2-associated X protein (Bax), phospho-Akt (p-Akt) and phospho-p70S6 kinase (p-p70S6K) were analyzed by western blotting. CD133, P-gp, Bcl-2 and Bax messenger ribonucleic acids were evaluated using semi-quantitative reverse transcriptase-polymerase chain reaction. Cell apoptosis was assessed by Hoechst 33258 staining. CD133+ cells were more resistant to 5-FU than CD133- cells, and showed higher expression of P-gp and Bcl-2 with lower expression of Bax. Furthermore, CD133 silencing enhanced 5-FU cytotoxicity and apoptotic characteristics, whereas CD133 overexpression increased 5-FU resistance. CD133 silencing and activation directly decreased and increased the expression of P-gp, Bcl‑2, p-Akt and p-p70S6K, respectively. Notably, Akt inhibition by LY294002 restored the 5-FU cytotoxicity suppressed by CD133 overexpression, while Akt activation by epidermal growth factor reversed the 5-FU cytotoxicity enhanced by CD133 silencing. Therefore, CD133 may inhibit 5-FU-induced apoptosis by regulating the expression of P-gp and Bcl-2 family mediated by phosphoinositide 3-kinase/Akt/p70S6K pathway in GC cells.
authors.affiliation: Department of First General Surgery, Shanghai Third People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 201900, P.R. China.
authors.forename: Youlong
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Department of First General Surgery, Shanghai Third People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 201900, P.R. China.
authors.forename: Jiwei
authors.initials: J
authors.lastname: Yu
authors.affiliation: Department of First General Surgery, Shanghai Third People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 201900, P.R. China.
authors.forename: Shoulian
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of First General Surgery, Shanghai Third People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 201900, P.R. China.
authors.forename: Ruiqi
authors.initials: R
authors.lastname: Lu
authors.affiliation: Department of First General Surgery, Shanghai Third People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 201900, P.R. China.
authors.forename: Jugang
authors.initials: J
authors.lastname: Wu
authors.affiliation: Department of First General Surgery, Shanghai Third People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 201900, P.R. China.
authors.forename: Bojian
authors.initials: B
authors.lastname: Jiang
mesh_terms: D000071916:AC133 Antigen; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism*; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D019008:Drug Resistance, Neoplasm; D005472:Fluorouracil / Q000494:pharmacology*; D015870:Gene Expression; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D010455:Peptides / Q000235:genetics / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D015398:Signal Transduction; D013274:Stomach Neoplasms
chemical_list: D000071916:AC133 Antigen; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D015703:Antigens, CD; D000964:Antimetabolites, Antineoplastic; D006023:Glycoproteins; C000606023:PROM1 protein, human; D010455:Peptides; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D005472:Fluorouracil