Targeting JARID1B’s demethylase activity blocks a subset of its functions in oral cancer

Abstract

Upregulation of the H3K4me3 demethylase JARID1B is linked to acquisition of aggressive, stem cell-like features by many cancer types. However, the utility of emerging JARID1 family inhibitors remains uncertain, in part because JARID1B’s functions in normal development and malignancy are diverse and highly context-specific. In this study, responses of oral squamous cell carcinomas (OSCCs) to catalytic inhibition of JARID1B were assessed using CPI-455, the first tool compound with true JARID1 family selectivity. CPI-455 attenuated clonal sphere and tumor formation by stem-like cells that highly express JARID1B while also depleting the CD44-positive and Aldefluor-high fractions conventionally used to designate OSCC stem cells. Silencing JARID1B abrogated CPI-455’s effects on sphere formation, supporting that the drug acted through this isoform. To further delineate CPI-455’s capacity to block JARID1B’s functions, its biologic effects were compared against those indicated by pathway analysis of the transcriptional profile produced by JARID1B knockdown. Downregulation of multiple gene sets related to stem cell function was consistent with the drug’s observed actions. However, strong E-Cadherin upregulation seen upon silencing JARID1B surprisingly could not be reproduced using CPI-455. Expressing a demethylase-inactive mutant of JARID1B demonstrated suppression of this transcript to be demethylase-independent, and the capacity of mutant JARID1B but not CPI-455 to modulate invasion provided a functional correlate of this finding. These results show that JARID1B catalytic inhibition effectively targets some stem cell-like features of malignancy but also reveal demethylase-independent actions refractory to inhibition. Future application of JARID1 inhibitors in combinatorial use for cancer therapy may be guided by these findings.

Biology and targeting of the Jumonji-domain histone demethylase family in childhood neoplasia: a preclinical overview

“…Identification of the KDM5-dependent drug-tolerant persister state motivated the development of the KDM5-specific pharmacologic inhibitor CPI-455 124 . This inhibitor has been shown to have efficacy against drug-resistant NSCLC, melanoma, colon, and breast cancer cells 124 , as well as KDM5B-high oral cancer 125 . Other inhibitors targeting the demethylase activity of the KDM5 family have also been developed, as recently reviewed 126 .…”

Chemical Inhibitors Targeting the Histone Lysine Demethylase Families with Potential for Drug Discovery

“…The crystal structure of the KDM5A/CPI-455 complex reveals that the inhibitor occupies the binding site of 2-OG, with the nitrile group interacting with the active site metal ion, the carbonyl oxygen forming a hydrogen bond with Nδ of N575, and the central aromatic core forming stacking with the side chains of Y472 and F480 [ 64 ] ( Figure 2 C). With the inhibition of KDM5B, CPI-455 reduces the stem-like properties of oral squamous cell carcinomas [ 105 ]. It also inhibits KDM5A.…”

JMJD family proteins in cancer and inflammation

“… 265 Likewise, CPI-455, the first tool compound selectively targeting the JARID1 family, inhibited the stem cell-like properties of oral cancer. 266 …”

“… 426 The inhibition of JARID1B by CPI-455 reduced the stem cell-like features of oral squamous cell carcinoma cells, but cells also displayed demethylase-independent activities refractory to inhibition. 266 JARID1A is highly expressed in drug tolerant persister (DTP) cells, a subpopulation of tumor cells that contributes to the growing number of drug resistant cells 427 such as TMZ-resistant glioblastoma cells. 428 Given that drug tolerance of tumor cells was partially dependent on demethylase activity, CPI-455 was used to reduce DTPs in multiple models.…”