TP53 genomic status regulates sensitivity of gastric cancer cells to the histone methylation inhibitor 3-deazaneplanocin A (DZNep).
OBJECTIVE
DZNep (3-deazaneplanocin A) depletes EZH2, a critical component of polycomb repressive complex 2 (PRC2), which is frequently deregulated in cancer. Despite exhibiting promising anticancer activity, the specific genetic determinants underlying DZNep responsiveness in cancer cells remain largely unknown. We sought to determine molecular factors influencing DZNep response in gastric cancer.


METHODS
Phenotypic effects of DZNep were evaluated in a panel of gastric cancer cell lines. Sensitive lines were molecularly interrogated to identify potential predictors of DZNep responsiveness. The functional importance of candidate predictors was evaluated using short hairpin RNA (shRNA) and siRNA technologies.


RESULTS
DZNep depleted PRC2 pathway components in almost all gastric cancer lines, however, only a subset of lines exhibited growth inhibition upon treatment. TP53 genomic status was significantly associated with DZNep cellular responsiveness, with TP53 wild-type (WT) lines being more sensitive (P < 0.001). In TP53-WT lines, DZNep stabilized p53 by reducing ubiquitin conjugation through USP10 upregulation, resulting in activation of canonical p53 target genes. TP53 knockdown in TP53-WT lines attenuated DZNep sensitivity and p53 target activation, showing the functional importance of an intact p53 pathway in regulating DZNep cellular sensitivity. In primary human gastric cancers, EZH2 expression was negatively correlated with p53 pathway activation, suggesting that higher levels of EZH2 may repress p53 activity.


CONCLUSIONS
Our results highlight an important role for TP53 genomic status in influencing DZNep response in gastric cancer. Clinical trials evaluating EZH2-targeting agents such as DZNep should consider stratifying patients with gastric cancer by their TP53 genomic status.
Cancer and Stem Cell Biology Program, Duke-NUS Graduate Medical School, Singapore.
Lai Ling
LL
Cheng
Yoko
Y
Itahana
Zheng Deng
ZD
Lei
Na-Yu
NY
Chia
Yonghui
Y
Wu
Yingnan
Y
Yu
Shen Li
SL
Zhang
Aye Aye
AA
Thike
Anuradha
A
Pandey
Steve
S
Rozen
Pieter Mathijs
PM
Voorhoeve
Qiang
Q
Yu
Puay Hoon
PH
Tan
Boon Huat
BH
Bay
Koji
K
Itahana
Patrick
P
Tan
D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D000071221:Enhancer of Zeste Homolog 2 Protein; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006657:Histones / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D008297:Male; D008745:Methylation / Q000187:drug effects; D008875:Middle Aged; D009154:Mutation; D063151:Polycomb Repressive Complex 2 / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013274:Stomach Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D016159:Tumor Suppressor Protein p53 / Q000235:genetics* / Q000378:metabolism; D054875:Ubiquitination / Q000187:drug effects; D055815:Young Adult
D006657:Histones; D016159:Tumor Suppressor Protein p53; C048460:3-deazaneplanocin; C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein; D063151:Polycomb Repressive Complex 2; D000241:Adenosine