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Aberrant activation of the CD45-Wnt signaling axis promotes stemness and therapy resistance in colorectal cancer cells.

ABSTRACT: Rationale: Chemoradiation (CRT) is commonly used as an adjuvant or neoadjuvant treatment for colorectal cancer (CRC) patients. However, resistant cells manage to survive and propagate after CRT, increasing the risk of recurrence. Thus, better understanding the mechanism of resistant cancer cells is required to achieve better clinical outcomes. Methods: Here, we explored gene expression profiling of CRC patient tumors to identify therapy resistance genes and discovered that protein tyrosine phosphatase receptor type C (PTPRC), which encodes CD45, was increased in remnant tumor tissues after CRT and correlated with metastasis. Through multiple validations using patient tumors and CRC cell lines, we found for the first time the increase of CD45 expression in CRC (EpCAM+) epithelial cells surviving after CRT. Thus, we investigated the biological role and downstream events of CD45 were explored in human CRC cells and CRC mouse models. Results: Increased CD45 expression in cancer cells in pretreated primary tumors accounts for poor regression and recurrence-free survival in CRT-treated patients. High CD45 expression promotes CRC cell survival upon 5-fluorouracil or radiation treatment, while CD45 depletion sensitizes CRC cells to CRT. Intriguingly, CD45 is preferentially expressed in cancer stem-like cells (CSCs), as determined by spheroid culture and the expression of CSC markers, and is required for the distinct functions of CSCs, such as cancer initiation, repopulation, and metastasis. Mechanistically, CD45 phosphatase activity promotes Wnt transcriptional activity by stabilizing the β-catenin protein, which collectively enhances stemness and the therapy-resistant phenotype. Conclusions: Our results highlight a novel function of CD45 as a mediator of CRT resistance and provide a potential therapy strategy for CRC therapy.

SUBMITTER: Park SY

PROVIDER: S-EPMC8419050 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Distant metastasis is, unfortunately, the leading cause of death in colorectal cancer (CRC). Approximately 50% of CRC patients develop liver metastases, while 10-30% of patients develop pulmonary metastases. The occurrence of metastasis is considered to be almost exclusively driven by cancer stem cells (CSCs) formation. However, the key molecules that confer the transformation to stem cells in CRC, and subsequent metastasis, remain unclear. Far upstream element-binding protein 1 (FUBP1), a transcriptional regulator of c-Myc, was screened in CSCs of CRC by mass spectrometry and was examined by immunohistochemistry in a cohort of CRC tissues. FUBP1 was upregulated in 85% of KRAS-mutant and 25% of wild-type CRC patients. Further, whether in KRAS-mutant or wild-type patients, elevated FUBP1 was positively correlated with CRC lymph node metastasis and clinical stage, and negatively associated with overall survival. Overexpression of FUBP1 significantly enhanced CRC cell migration, invasion, tumor sphere formation, and CD133 and ALDH1 expression in vitro, and tumorigenicity in vivo. Mechanistically, FUBP1 promoted the initiation of CSCs by activating Wnt/β-catenin signaling via directly binding to the promoter of DVL1, a potent activator of β-catenin. Knockdown of DVL1 significantly inhibited the transformation to stem cells in, as well as the tumorigenicity of, CRC. Activation of Wnt/β-catenin signaling by DVL1 increased pluripotent transcription factors, including c-Myc, NANOG, and SOX2. Moreover, FUBP1 was upregulated at the post-transcriptional level. Elevated FUBP1 levels in KRAS wild-type CRC patients is due to the decrease in Smurf2, which promotes ubiquitin-mediated degradation of FUBP1. In contrast, FUBP1 was upregulated in KRAS-mutant patients through both inhibition of caspase 3-dependent cleavage and decreased Smurf2. Our results demonstrate, for the first time, that FUBP1 is an oncogene, initiating the development of CSCs, as well as a new powerful endogenous Wnt-signaling agonist that could provide an important prognostic factor and therapeutic target for metastasis in both KRAS-mutant and wild-type CRC.

Project description:BACKGROUND:Aberrant expression of transcription Factor AP-2 Gamma (TFAP2C) has been reported to be implicated in malignant process of many cancers. The purpose of this study is to investigate the clinical significance and biological roles of TFAP2C in colorectal cancer (CRC). METHODS:TFAP2C expression was evaluated by real-time PCR, Western blot and immunohistochemistry (IHC) respectively in clinical CRC tissues. Statistical analysis was performed to explore the correlation between TFAP2C expression and clinicopathological features, and overall and progression-free survival in CRC patients. In vitro and in vivo assays were performed to assess the biological roles of TFAP2C in CRC cells. Western blot, luciferase and Chromatin immunoprecipitation (ChIP) assays were used to identify the underlying pathway mediating the biological roles of TFAP2C in CRC. RESULTS:TFAP2C is robustly upregulated in CRC tissues and cells, and high expression of TFAP2C correlates with advanced clinicopathological features, poor prognosis and disease progression in CRC patients. Furthermore, upregulating TFAP2C enhances spheroids formation ability, the fraction of SP cells, expression of stem cell factors and the mitochondrial potential, and reduces the apoptosis induced by 5-fluorouracil in colorectal cancer cells in vitro, and promotes stemness and chemoresistance of CRC cells in vivo; while silencing TFAP2C yields an opposite effect. Importantly, downregulation of TFAP2C dramatically restores chemotherapeutic sensitivity of CRC cells to 5-FU in vivo. Our results further demonstrate that TFAP2C promotes stemness and chemoresistance of CRC cells to 5-FU by inhibiting Hippo signaling via transcriptionally upregulating ROCK1 and ROCK2 in CRC cells. CONCLUSION:Our findings indicate that TFAP2C may serve as a novel prognostic factor in CRC patients, and a therapeutic target for the treatment of CRC, suggesting that silencing TFAP2C in combination with 5-FU may be an effective therapeutic strategy to improve survival in CRC patients.

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Aberrant activation of the CD45-Wnt signaling axis promotes stemness and therapy resistance in colorectal cancer cells.

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