Chromobox 4 (CBX4) promotes tumor progression and stemness via activating CDC20 in gastric cancer

Abstract

Background: The Chromobox homolog 4 (CBX4) has been found to be overexpressed in multiple malignancies. However, the associations between CBX4 and gastric cancer (GC) have remained unclear. This study aimed to determine the biological roles of CBX4 in GC and identify effective therapeutic targets. Methods:The 3-(4,5-dimethylthiazol-2-yl) (MTT) assays were used to screen CBX family members.Differential analysis was utilized to evaluate the CBX4 levels. Kaplan-Meier analysis was used to perform prognostic analysis. Western blotting assay, quantitative polymerase chain reaction (qPCR) assay and immunohistochemistry (IHC) were used to assess CBX4 expressions. Colony formation assay, Cell Counting Kit-8 (CCK-8) assay, and Transwell assay were used to assess progression features of cells. The tail vein injection model was utilized to determine the metastatic efficacy of GC cells. Tumor sphere formation assay was used to assess tumor stemness maintenance ability. Chromatin immunoprecipitation (ChIP)-qPCR assay was used to evaluate the associations between CBX4 and CDC20. A subcutaneous tumor model was used to assess the in vivo growth ability of GC. Results:The MTT assay revealed that only CBX4 inhibition could lead to notable restriction of GC growth, as compared to others. Differential analysis suggested that CBX4 was upregulated in tumor samples relative to normal tissues. Less favorable overall survival (OS) outcomes were noticed in GC patients with high CBX4 in comparison to those with low CBX4. High CBX4 could notably enhance cell proliferation capacity, migration ability, and in vivo metastatic efficacy. Gene set enrichment analysis (GSEA) indicated the relationships between CBX4 and GC stemness, and CBX4 overexpression could remarkably elevate self-renewal ability of GC cells. In addition, CBX4 could mainly promote CDC20 messenger RNA (mRNA) levels, and targeting CBX4 suppressed the relative CDC20 levels. The ChIP-qPCR assay further demonstrated that CBX4 coordinated with H3K4me3 to bind at the CDC20 promoter region. Additionally, CBX4 depended on CDC20 to drive GC growth. Lastly, downregulated CBX4 could notably inhibit the growth of GC in vivo.Conclusions: This study highlights the oncogenic roles of CBX4 in GC. CBX4 activates CDC20 to maintain stemness features of GC, thereby creating therapeutic vulnerabilities in the treatment of GC.

Chromobox proteins in cancer: Multifaceted functions and strategies for modulation (Review)

“…Expression of CBXs in cancers. Compared with normal tissues or paracancerous tissues, the expression of all or some of the CBX1/2/3/4/5/8 members is upregulated in most cancer tissues, including glioma (67-69), tongue squamous cell carcinoma (TSCC) (70), head and neck squamous cell carcinoma (HNSCC) (71), breast cancer (BC) (15,(72)(73)(74)(75)(76)(77)(78)(79)(80), non-small cell lung cancer (NSCLC) (81)(82)(83)(84)(85), esophageal cancer (EC) (86)(87)(88)(89)(90), gastric cancer (GC) (91)(92)(93)(94)(95)(96)(97)(98), pancreatic adenocarcinoma (PAAD) (99,100), colorectal cancer (CRC) (101-104), urinary bladder cancer (UBC) (105), sarcoma (106) and osteosarcoma (107,108). As a tumor suppressor, CBX7 is expressed at low levels in most tumors, such as glioma, HNSCC (71), EC (87,88), GC (93)(94)(95)(96)(97)(98), PAAD (109), CRC (103,104), clear cell r...…”

“…CBX3 is a poor prognostic factor in as many as 13 tumor types (67,69-71,80 ,81,84,86-88,101,106,110,111,114,116,122,123). CBX4 is of prognostic value in BC (76,80), LUAD (85), EC (86)(87)(88), GC (92,94,95,98), HCC (11) and ccRCC (110). In addition, patients with BC (80), LUAD (84), GC (94)(95)(96)(97)(98), CRC (103), sarcoma (106), SKCM (113) with upregulated CBX5 and HNSCC (71) and ccRCC (110) with downregulated CBX5 have poor prognosis.…”

“…Mechanistically, c-Myc may upregulate CBX3 by directly binding the E-box element in the first intron of the CBX3 gene, and upregulated CBX3 in turn inhibits the expression of miR-451a by enhancing H3K9 methylation at the promoter region (129). CBX4 and histone H3 lysine K4 trimethylation (H3K4me3) coordinate and combine with the cell division cycle (CDC)20 promoter region to promote CDC20 expression and significantly enhance and maintain GC cell proliferation, migration and metastasis in vivo (92). Dicer is upregulated in cholangiocellular carcinoma (CCCA) and its nuclear form may interact with CBX5.…”

The potential role of CDC20 in tumorigenesis, cancer progression and therapy: A narrative review

“…[50] Furthermore, CBX4 mainly promotes CDC20 mRNA levels and notably enhances cell proliferation capacity, migration ability, and in vivo metastatic efficacy. [51] In renal cancer, CDC20 promotes proliferation by increasing the protein levels of securin, cyclin B1, and cyclin A. [55] In addition, CYP1B1 may promote renal cell proliferation, migration, and invasion, and inhibit apoptosis by inducing CDC20 expression.…”

“…[32] Besides, CBX4 promoted CDC20 mRNA levels and notably enhanced cell migration ability and metastatic efficacy as a positive regulatory factor. [51] The lncRNA SpRY-IT4 also promotes cell invasion by regulating CDC20 in pancreatic cancer cells. [53] Furthermore, CYP1B1 may promote renal cell migration and invasion by inducing CDC20 expression.…”