Bufalin inhibits pancreatic cancer by inducing cell cycle arrest via the c-Myc/NF-κB pathway.
BACKGROUND
Bufalin, a cardiotonic steroid isolated from toad venom (bufo gargarizans Cantor or B. melanotictus Schneider), has widely demonstrated antitumor effects and exhibits potential antitumor activity in various human cancer cells lines.


OBJECTIVE
The main characteristic of cancers including pancreatic cancer is the ability of uncontrolled proliferation. The aim of this study is to clarify the underlying mechanism by which bufalin inhibits pancreatic cancer cell proliferation.


METHODS
The effect of bufalin on the suppression of tumor growth in vivo was studied in a bioluminescent mouse model generated using the pancreatic cancer cell line BxPC3-luc2 and the cytotoxicity was evaluated in BcPc3 and Sw1990 cells with MTT. Flow cytometry and western blotting analyses were utilized to detect the effect of bufalin on the cell cycle and to detect the cell cycle-related proteins, respectively. Then, a luciferase reporter assay was applied to screen the activity of potent transcription factors following bufalin exposure and their expression was detected by western blotting.


RESULTS
Bufalin suppressed tumor growth in a bioluminescence mouse model generated using BxPC3-luc2 cells and inhibited cell proliferation in vitro through inducing cell cycle arrest at S phase. Bufalin treatment inhibited cyclin D1 and cyclin E1 expression and therefore increased expression of p27, a regulatory molecular that controls cell cycle transition from S to G2 phase. Furthermore, luciferase reporter screening studies revealed that bufalin inhibited the expression and activity of the transcription factors c-Myc and NF-κB, which might cause cell cycle arrest at S phase and the inhibition of cell proliferation.


CONCLUSIONS
Taken together, our results indicate that bufalin can inhibit pancreatic cancer by targeting c-Myc, thus suggesting that the mechanism of c-Myc regulation by bufalin might be worthy of further study regarding its potential as a therapeutic target for pancreatic cancer treatment.
The Second Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou 310005, China.
Xia
X
Liu
The Second Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou 310005, China.
Xiang-Yang
XY
Xiao
Experimental Animal Research Center, Zhejiang Chinese Medical University, Hangzhou 310053, China.
Qi-Yang
QY
Shou
The Second Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou 310005, China.
Jun-Feng
JF
Yan
The Second Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou 310005, China.
Long
L
Chen
The Second Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou 310005, China. Electronic address: fhy131@126.com.
Hui-Ying
HY
Fu
The Second Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou 310005, China. Electronic address: xhwangjianchao@163.com.
Jian-Chao
JC
Wang
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002018:Bufanolides / Q000494:pharmacology*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D002945:Cisplatin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D015972:Gene Expression Regulation, Neoplastic; D017930:Genes, Reporter; D006801:Humans; D008156:Luciferases / Q000096:biosynthesis / Q000235:genetics; D008297:Male; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism*; D059807:S Phase Cell Cycle Checkpoints / Q000187:drug effects*; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D014162:Transfection; D047368:Tumor Burden / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
D000970:Antineoplastic Agents; D002018:Bufanolides; D018797:Cell Cycle Proteins; C489427:MYC protein, human; D016328:NF-kappa B; D016271:Proto-Oncogene Proteins c-myc; D008156:Luciferases; D002945:Cisplatin; C022777:bufalin
Bufalin; Cell cycle arrest; Pancreatic cancer; Traditional Chinese medicines; c-Myc/NF- κB pathway