Abstract
F-box and WD repeat domain-containing 5 (FBXW5), with WD40 repeats, can bind to the PPxY sequence of the large tumor suppressor kinases 1/2 (LATS1/2) kinase domain, resulting in ubiquitination. Ubiquitination and the subsequent degradation of LATS1/2 abrogate the Hippo pathway and worsen gastric cancer (GC). However, the effects and molecular mechanisms of FBXW5 in GC remain unexplored. To elucidate the clinical significance of FBXW5, immunohistochemistry was conducted to reveal the positive correlation between FBXW5 expression and lymph node metastasis (p < 0.001) and TNM stage (training cohort: p = 0.018; validation cohort: p = 0.001). Further, patients with high FBXW5 expression were found to have poor prognosis (training cohort: log-rank p = 0.020; validation cohort: log-rank p = 0.025). Cell experiments revealed the promoting effects of FBXW5 on the proliferation, invasion, metastasis, and chemoresistance of GC cells. Blocking LATS1-YAP1 leads to the loss of FBXW5-mediated regulation of the Hippo pathway and partial functions. Further, co-immunoprecipitation and in vivo ubiquitination assays revealed the interaction between FBXW5 and LATS1, which promoted the ubiquitination and degradation of LATS1. Based on mouse xenograft assays, FBXW5 silencing attenuated the growth of subcutaneous tumor xenografts. Altogether, FBXW5 was found to inactivate the Hippo signaling pathway by enhancing LATS1 ubiquitination and degradation, which promoted the invasion, metastasis, and drug resistance of GC cells.
Highlights
670,000 new gastric cancer (GC) cases and 490,000 GC-related deaths are reported each year in China [1]
Abrogating the Hippo pathway signal impairs large tumor suppressor kinases 1/2 (LATS1/2)-mediated phosphorylation of yes-associated protein (YAP) or WW domaincontaining transcription regulator 1 (TAZ) [6], which acts as a transcriptional coactivator with TEA domain-containing sequencespecific transcription factors after translocation to the nucleus to activate the transcription of downstream target genes, degrading GC [7]
By searching the Human Protein Atlas Image Classification database, we found that F-box and WD repeat domain-containing 5 (FBXW5) is broadly expressed in human cancers, including GC
Summary
670,000 new gastric cancer (GC) cases and 490,000 GC-related deaths are reported each year in China [1]. FBXW5 was reported to interact with cullin 4A–RING ubiquitin ligase–DNA damagebinding protein 1 (CUL4A–DDB1) and act as a major substrate recognition component for the ubiquitination and degradation of deleted in liver cancer 1 (DLC1), which promotes tumor progression. A high level of FBXW5 underlies tumor FBXW5 promotes chemoresistance in GC cells invasion, lymph node metastasis, TNM stage, and poor prognosis We conducted CCK8 assays using gradient concentrations of in GC patients. Degradation, which in turn promoted the invasion, metastasis, fluorouracil, whereas the upregulation of FBXW5 increased the and chemoresistance of GC cells. The findings of this study resistance of cells to 5-fluorouracil (Fig. 3A) Similar results to those provide novel insights into targeted therapy for GC. Obtained for 5-fluorouracil were found using cisplatin (Fig. 3B)
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