FOXP1 inhibits pancreatic cancer growth by transcriptionally regulating IRF1 expression

The FOXP1-ABCG2 axis promotes the proliferation of cancer stem cells and induces chemoresistance in pancreatic cancer

Pancreatic cancer is an aggressive disease with low survival and high recurrence rates. A major obstacle in treating pancreatic cancer is the frequent development of chemoresistance to the standard therapeutic drug, gemcitabine. One mechanism by which pancreatic cancer develops chemoresistance is through the proliferation of cancer stem cells (CSC). However, the mechanisms regulating stemness in chemoresistant tumors remain unclear. Here, we found that the expression of the transcription factor Forkhead Box P1 (FOXP1) was elevated in chemoresistant pancreatic cancer and crucial for establishing CSC characteristics. Silencing FOXP1 reduced the expressions of stemness-associated genes and diminished the formation of both spheroids and colonies, highlighting the crucial role of FOXP1 in regulating stemness in chemoresistant tumor cells. Mechanistically, we discovered that FOXP1 regulates the expression of ATP-binding cassette superfamily G member 2 (ABCG2), which induces the efflux of gemcitabine. Knockdown of FOXP1 reduced the expression of ABCG2, resulting in decreased proliferation and increased sensitivity to gemcitabine. Moreover, the inhibition of FOXP1 in orthotopic mouse models reduced tumor growth and proliferation, and enhanced sensitivity to gemcitabine. Together, our data reveal FOXP1 as a potent oncogene that promotes CSC growth in chemoresistant pancreatic cancer.

miR-103 promotes esophageal squamous cell carcinoma metastasis by targeting FOXP1

Esophageal squamous cell carcinoma (ESCC), a prevalent malignancy within the digestive tract, is associated with a significantly high mortality rate. MicroRNAs were already demonstrated to work in a wide range of tumors. The objective of the present research was to elucidate the involvement of miR-103 in the pathogenesis of ESCC and to explore its underlying mechanisms of action. Real-time quantitative polymerase chain reaction was used to detect miR-103 expressions in ESCC tissues and cells. The clinical significance of these expressions was assessed by a series of statistical analyses. Transwell assay was used to study the impact of miR-103 on migration and invasion ability of ESCC cells. Furthermore, a dual luciferase reporter gene method was adopted to study the association of miR-103 with the targeting of forkhead box protein 1 (FOXP1). miR-103 was significantly up-regulation in ESCC tissues and cell lines. Clinically, high miR-103 expression was associated with negative prognosis in ESCC. The low miR-103 expression significantly inhibited cell proliferation, migration and invasion in ESCC cell lines. Furthermore, miR-103 regulated the mechanism of action of ESCC by targeting FOXP1. In this study, we found that miR-103 may serve as a biomarker for ESCC prognosis. miR-103 may promote ESCC cell metastasis by targeting FOXP1. These studies may elucidate the potential of miR-103 as a novel target for the treatment of ESCC.

FOXP1 phosphorylation antagonizes its O-GlcNAcylation in regulating ATR activation in response to replication stress

ATR signaling is essential in sensing and responding to the replication stress; as such, any defects can impair cellular function and survival. ATR itself is activated via tightly regulated mechanisms. Here, we identify FOXP1, a forkhead-box-containing transcription factor, as a regulator coordinating ATR activation. We show that, unlike its role as a transcription factor, FOXP1 functions as a scaffold and directly binds to RPA-ssDNA and ATR-ATRIP complexes, facilitating the recruitment and activation of ATR. This process is regulated by FOXP1 O-GlcNAcylation, which represses its interaction with ATR, while CHK1-mediated phosphorylation of FOXP1 inhibits its O-GlcNAcylation upon replication stress. Supporting the physiological relevance of this loop, we find pathogenic FOXP1 mutants identified in various tumor tissues with compromised ATR activation and stalled replication fork stability. We thus conclude that FOXP1 may serve as a potential chemotherapeutic target in related tumors.

An integrated analysis of the anticarcinogenic role of forkhead box protein 1 in oesophageal squamous cell carcinoma

Forkhead box protein 1 (FOXP1) serves as a tumour promoter or suppressor depending on different cancers, but its effect in oesophageal squamous cell carcinoma has not been fully elucidated. This study investigated the role of FOXP1 in oesophageal squamous cell carcinoma through bioinformatics analysis and experimental verification. We determined through public databases that FOXP1 expresses low in oesophageal squamous cell carcinoma compared with normal tissues, while high expression of FOXP1 indicates a better prognosis. We identified potential target genes regulated by FOXP1, and explored the potential biological processes and signalling pathways involved in FOXP1 in oesophageal squamous cell carcinoma through GO and KEGG enrichment, gene co-expression analysis, and protein interaction network construction. We also analysed the correlation between FOXP1 and tumour immune infiltration levels. We further validated the inhibitory effect of FOXP1 on the proliferation of oesophageal squamous cell carcinoma cells through CCK-8, colony formation and subcutaneous tumour formation assays. This study revealed the anticarcinogenic effect of FOXP1 in oesophageal squamous cell carcinoma, which may serve as a novel biological target for the treatment of tumour.

Roles of Interferon Regulatory Factor 1 in Tumor Progression and Regression: Two Sides of a Coin

IRF1 is a transcription factor well known for its role in IFN signaling. Although IRF1 was initially identified for its involvement in inflammatory processes, there is now evidence that it provides a function in carcinogenesis as well. IRF1 has been shown to affect several important antitumor mechanisms, such as induction of apoptosis, cell cycle arrest, remodeling of tumor immune microenvironment, suppression of telomerase activity, suppression of angiogenesis and others. Nevertheless, the opposite effects of IRF1 on tumor growth have also been demonstrated. In particular, the "immune checkpoint" molecule PD-L1, which is responsible for tumor immune evasion, has IRF1 as a major transcriptional regulator. These and several other properties of IRF1, including its proposed association with response and resistance to immunotherapy and several chemotherapeutic drugs, make it a promising object for further research. Numerous mechanisms of IRF1 regulation in cancer have been identified, including genetic, epigenetic, transcriptional, post-transcriptional, and post-translational mechanisms, although their significance for tumor progression remains to be explored. This review will focus on the established tumor-suppressive and tumor-promoting functions of IRF1, as well as the molecular mechanisms of IRF1 regulation identified in various cancers.