title: Multidrug resistance-associated protein 3 confers resistance to chemoradiotherapy for rectal cancer by regulating reactive oxygen species and caspase-3-dependent apoptotic pathway.
abstract: This study aimed to clarify the role of multidrug resistance-associated protein 3 (MRP3) in resistance to neoadjuvant chemoradiotherapy and long-term prognosis of advanced rectal cancer. Immunohistochemistry was used to measure MRP3 expression in biopsy specimens of 144 stage II-III rectal cancer patients who received preoperative chemoradiotherapy. The effect of MRP3 expression on short-term pathological response and postoperative long-term prognosis were assessed using the Cox proportional hazards model. Short interfering RNAs targeting MRP3 were synthesized and used to transfect human colorectal carcinoma cell lines. The effect of MRP3 down-regulation on cell proliferation and apoptosis in response to 5-fluorouracil and/or irradiation were examined in vitro and in xenograft mouse models, respectively. The content of intracellular reactive oxygen species and the activity of caspase-3-dependent apoptotic pathway in response to irradiation were further evaluated. High expression (immunoreactive score > 6) of MRP3 significantly predicted poor pathological response to chemoradiotherapy (tumor regression grade ≤ 2 vs. ≥3, p = 0.002) in univariate analysis and unfavorable long-term prognosis (5-year overall survival: HR = 1.612, 95% CI, 1.094-2.375, p = 0.016; 5-year disease-free survival: HR = 1.513, 95% CI, 1.041-2.200, p = 0.030) in multivariate Cox analysis. MRP3 down-regulation significantly increased 5-fluorouracil or irradiation-induced cell apoptosis and attenuated tumor growth following irradiation in animal models. MRP3 inhibition significantly reduced intracellular reactive oxygen species exporting from cells following irradiation, and increased expression of cleaved poly ADP-ribose polymerase and caspase-3. Aberrant expression of MRP3 in rectal cancer confers chemo-radioresistance. MRP3 might be a predictive factor and an attractive target in treating advanced rectal cancer.
authors.affiliation: Department of Colorectal Surgery, Changhai Hospital, Second Military Medical University, Shanghai, China; Department of General Surgery, 306 Hospital of PLA, Beijing, China.
authors.forename: Zhiqi
authors.initials: Z
authors.lastname: Yu
authors.affiliation: Department of Colorectal Surgery, Changhai Hospital, Second Military Medical University, Shanghai, China.
authors.forename: Chang
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Colorectal Surgery, Changhai Hospital, Second Military Medical University, Shanghai, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Colorectal Surgery, Changhai Hospital, Second Military Medical University, Shanghai, China.
authors.forename: Junjie
authors.initials: J
authors.lastname: Xing
authors.affiliation: Department of Colorectal Surgery, Changhai Hospital, Second Military Medical University, Shanghai, China.
authors.forename: Haifeng
authors.initials: H
authors.lastname: Gong
authors.affiliation: Department of Colorectal Surgery, Changhai Hospital, Second Military Medical University, Shanghai, China.
authors.forename: Enda
authors.initials: E
authors.lastname: Yu
authors.affiliation: Department of Colorectal Surgery, Changhai Hospital, Second Military Medical University, Shanghai, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Department of Radiotherapy, Changhai Hospital, Second Military Medical University, Shanghai, China.
authors.forename: Xiaoqing
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Epidemiology, Second Military Medical University, Shanghai, China. Electronic address: gcao@smmu.edu.cn.
authors.forename: Guangwen
authors.initials: G
authors.lastname: Cao
authors.affiliation: Department of Colorectal Surgery, Changhai Hospital, Second Military Medical University, Shanghai, China. Electronic address: fugang416@126.com.
authors.forename: Chuangang
authors.initials: C
authors.lastname: Fu
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism*; D049109:Cell Proliferation / Q000187:drug effects; D059248:Chemoradiotherapy; D019008:Drug Resistance, Neoplasm; D005260:Female; D005472:Fluorouracil / Q000494:pharmacology; D019073:HT29 Cells; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008875:Middle Aged; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000502:physiology*; D016016:Proportional Hazards Models; D011836:Radiation Tolerance; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012004:Rectal Neoplasms / Q000378:metabolism* / Q000401:mortality / Q000473:pathology / Q000628:therapy; D016896:Treatment Outcome; D023041:Xenograft Model Antitumor Assays; D055815:Young Adult
chemical_list: D000964:Antimetabolites, Antineoplastic; D053148:Caspase 3; D005472:Fluorouracil; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D017382:Reactive Oxygen Species; C114462:multidrug resistance-associated protein 3; C505407:CASP3 protein, human
keywords: Caspase-3; Multidrug resistance-associated protein 3; Neoadjuvant chemoradiotherapy; Poly ADP-ribose polymerase; Reactive oxygen species; Rectal cancer