DCLK1 inhibition attenuates tumorigenesis and improves chemosensitivity in esophageal squamous cell carcinoma by inhibiting β-catenin/c-Myc signaling

DCLK1 in gastrointestinal cancer: A driver of tumor progression and a promising therapeutic target

Cancers of the gastrointestinal (GI) tract, including colorectal, pancreatic, and hepatocellular carcinomas, represent a significant global health burden due to their high incidence and mortality rates. Doublecortin-like kinase 1 (DCLK1), initially identified for its role in neurogenesis, has emerged as a crucial player in GI cancer progression. This review comprehensively examines the multifaceted roles of DCLK1 in GI cancers, focusing on its structural isoforms, functions in normal and inflammatory states, and contributions to cancer progression and metastasis. DCLK1 is overexpressed in various GI cancers and is associated with poor prognosis, enhanced tumorigenic potential, and increased metastatic capacity. The review discusses the molecular mechanisms through which DCLK1 influences cancer stem cell maintenance, epithelial-mesenchymal transition (EMT), and cell survival pathways, as well as its interactions with key signaling pathways such as Notch, WNT/β-catenin, and NF-κB. The potential of DCLK1 as a therapeutic target is also explored, highlighting preclinical and early clinical efforts to inhibit its function using small molecule inhibitors or monoclonal antibodies. Despite significant advancements, further research is needed to fully elucidate DCLK1's role in GI cancers and to develop effective therapeutic strategies targeting this protein.

DCLK1 and its oncogenic functions: A promising therapeutic target for cancers

Doublecortin-like kinase 1 (DCLK1), a significant constituent of the protein kinase superfamily and the doublecortin family, has been recognized as a prooncogenic factor that exhibits a strong association with the malignant progression and clinical prognosis of various cancers. DCLK1 serves as a stem cell marker that governs tumorigenesis, tumor cell reprogramming, and epithelial-mesenchymal transition. Multiple studies have indicated the capable of DCLK1 in regulating the DNA damage response and facilitating DNA damage repair. Additionally, DCLK1 is involved in the regulation of the immune microenvironment and the promotion of tumor immune evasion. Recently, DCLK1 has emerged as a promising therapeutic target for a multitude of cancers. Several small-molecule inhibitors of DCLK1 have been identified. Nevertheless, the biological roles of DCLK1 are mainly ambiguous, particularly with the disparities between its α- and β-form transcripts in the malignant progression of cancers, which impedes the development of more precisely targeted drugs. This article focuses on tumor stem cells, tumor epithelial-mesenchymal transition, the DNA damage response, and the tumor microenvironment to provide a comprehensive overview of the association between DCLK1 and tumor malignant progression, address unsolved questions and current challenges, and project future directions for targeting DCLK1 for the diagnosis and treatment of cancers.

Targeting doublecortin-like kinase 1 reveals a novel strategy to circumvent chemoresistance and metastasis in ovarian cancer

Ovarian cancer (OvCa) has a dismal prognosis because of its late-stage diagnosis and the emergence of chemoresistance. Doublecortin-like kinase 1 (DCLK1) is a serine/threonine kinase known to regulate cancer cell "stemness", epithelial-mesenchymal transition (EMT), and drug resistance. Here we show that DCLK1 is a druggable target that promotes chemoresistance and tumor progression of high-grade serous OvCa (HGSOC). Importantly, high DCLK1 expression significantly correlates with poor overall and progression-free survival in OvCa patients treated with platinum chemotherapy. DCLK1 expression was elevated in a subset of HGSOC cell lines in adherent (2D) and spheroid (3D) cultures, and the expression was further increased in cisplatin-resistant (CPR) spheroids relative to their sensitive controls. Using cisplatin-sensitive and resistant isogenic cell lines, pharmacologic inhibition (DCLK1-IN-1), and genetic manipulation, we demonstrate that DCLK1 inhibition was effective at re-sensitizing cells to cisplatin, reducing cell proliferation, migration, and invasion. Using kinase domain mutants, we demonstrate that DCLK1 kinase activity is critical for mediating CPR. The combination of cisplatin and DCLK1-IN-1 showed a synergistic cytotoxic effect against OvCa cells in 3D conditions. Targeted gene expression profiling revealed that DCLK1 inhibition in CPR OvCa spheroids significantly reduced TGFβ signaling, and EMT. We show in vivo efficacy of combined DCLK1 inhibition and cisplatin in significantly reducing tumor metastases. Our study shows that DCLK1 is a relevant target in OvCa and combined targeting of DCLK1 in combination with existing chemotherapy could be a novel therapeutic approach to overcome resistance and prevent OvCa recurrence.

Thrombin induces IL-8/CXCL8 expression by DCLK1-dependent RhoA and YAP activation in human lung epithelial cells

Background

Doublecortin-like kinase 1 (DCLK1) has been recognized as a marker of cancer stem cell in several malignancies. Thrombin is crucial in asthma severity as it can promote IL-8/CXCL8 production in lung epithelial cells, which is a potent chemoattractant for neutrophils. However, the pathologic role of DCLK1 in asthma and its involvement in thrombin-stimulated IL-8/CXCL8 expression remain unknown.

Methods

IL-8/CXCL8, thrombin, and DCLK1 expression were observed in the lung tissues of severe asthma patients and ovalbumin (OVA)-induced asthmatic mice model. A549 and BEAS-2B cells were either pretreated with inhibitors or small interfering RNAs (siRNAs) before being treated with thrombin. IL-8/CXCL8 expression and the molecules involved in signaling pathway were performed using ELISA, luciferase activity assay, Western blot, or ChIP assay.

Results

IL-8/CXCL8, thrombin, and DCLK1 were overexpressed in the lung tissues of severe asthma patients and ovalbumin (OVA)-induced asthmatic mice model. Our in vitro study found that DCLK siRNA or LRKK2-IN-1 (DCLK1 inhibitor) attenuated IL-8/CXCL8 release after thrombin induction in A549 and BEAS-2B cells. Thrombin activated DCLK1, RhoA, and YAP in a time-dependent manner, in which DCLK1 siRNA inhibited RhoA and YAP activation. YAP was dephosphorylated on the Ser127 site after thrombin stimulation, resulting in YAP translocation to the nucleus from the cytosol. DCLK1, RhoA and YAP activation following thrombin stimulation were inhibited by U0126 (ERK inhibitor). Moreover, DCLK1 and YAP siRNA inhibited κB-luciferase activity. Thrombin stimulated the recruitment of YAP and p65 to the NF-κB site of the IL-8/CXCL8 promoter and was inhibited by DCLK1 siRNA.

Conclusions

Thrombin activates the DCLK1/RhoA signaling pathway, which promotes YAP activation and translocation to the nucleus from the cytosol, resulting in YAP/p65 formation, and binding to the NF-κB site, which enhances IL-8/CXCL8 expression. DCLK1 might be essential in thrombin-stimulated IL-8/CXCL8 expression in asthmatic lungs and indicates a potential therapeutic strategy for severe asthma treatment.

KIFC3 promotes proliferation, migration and invasion of esophageal squamous cell carcinoma cells by activating EMT and β-catenin signaling

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is one of the most common malignancies. A total of 45 kinesin superfamily proteins (KIFs) have been identified in humans, among which several family members have demonstrated varied functions in tumor pathobiology via different mechanisms, including regulation of cell cycle progression and metastasis. KIFC3 has microtubule motor activity and is involved in cancer cell invasion and migration, as well as survival. However, the role of KIFC3 in ESCC is still unknown.

AIM

To evaluate the role of KIFC3 in ESCC and the underlying mechanisms.

METHODS

Expression of KIFC3 was evaluated in ESCC tissues and adjacent normal esophageal tissues. The prognostic value of KIFC3 was analyzed using Kaplan–Meier Plotter. Colony formation, EdU assays, cell cycle analysis, Transwell assay, immunofluorescence, and western blotting were performed in ESCC cell lines after transfection with pLVX-Puro-KIFC3-shRNA- and pLVX-Puro-KIFC3-expressing lentiviruses. A xenograft tumor model in nude mice was used to evaluate the role of KIFC3 in tumorigenesis. Inhibitor of β-catenin, XAV-939, was used to clarify the mechanism of KIFC3 in ESCC. To analyze the differences between groups, t test and nonparametric tests were used. P < 0.05 was considered statistically significant.

RESULTS

Immunohistochemical staining indicated that KIFC3 was upregulated in ESCC tissues compared with adjacent normal tissues. Kaplan–Meier Plotter revealed that overexpressed KIFC3 was associated with poor prognosis in ESCC patients. Colony formation and EdU assay showed that KIFC3 overexpression promoted cell proliferation, while KIFC3 knockdown inhibited cell proliferation in ESCC cell lines. In addition, cell cycle analysis showed that KIFC3 overexpression promoted cell cycle progression. KIFC3 knockdown suppressed ESCC tumorigenesis in vivo. Transwell assay and western blotting revealed that KIFC3 overexpression promoted cell migration and invasion, as well as epithelial–mesenchymal transition (EMT), while KIFC3 knockdown showed the opposite results. Mechanistically, KIFC3 overexpression promoted β-catenin signaling in KYSE450 cells; however, the role of KIFC3 was abolished by XAV-939, the inhibitor of β-catenin signaling.

CONCLUSION

KIFC3 was overexpressed in ESCC and was associated with poor prognosis. Furthermore, KIFC3 promoted proliferation, migration and invasion of ESCC via β-catenin signaling and EMT.

Targeting DCLK1 overcomes 5-fluorouracil resistance in colorectal cancer through inhibiting CCAR1/β-catenin pathway-mediated cancer stemness

Background

To date, 5‐fluorouracil‐based chemotherapy is very important for locally advanced or metastatic colorectal cancer (CRC). However, chemotherapy resistance results in tumor recurrence and metastasis, which is a major obstacle for treatment of CRC.

Methods

In the current research, we establish 5‐fluorouracil resistant cell lines and explore the potential targets associated with 5‐fluorouracil resistance in CRC. Moreover, we perform clinical specimen research, in vitro and in vivo experiments and molecular mechanism research, to reveal the biological effects and the mechanism of DCLK1 promoting 5‐fluorouracil resistance, and to clarify the potential clinical value of DCLK1 as a target of 5‐fluorouracil resistance in CRC.

Results

We discover that doublecortin‐like kinase 1 (DCLK1), a cancer stem cell maker, is correlated with 5‐fluorouracil resistance, and functionally promotes cancer stemness and 5‐fluorouracil resistance in CRC. Mechanistically, we elucidate that DCLK1 interacts with cell cycle and apoptosis regulator 1 (CCAR1) through the C‐terminal domain, and phosphorylates CCAR1 at the Ser343 site, which is essential for CCAR1 stabilisation. Moreover, we find that DCLK1 positively regulates β‐catenin signalling via CCAR1, which is responsible for maintaining cancer stemness. Subsequently, we prove that blocking β‐catenin inhibits DCLK1‐mediated 5‐fluorouracil resistance in CRC cells. Importantly, we demonstrate that DCLK1 inhibitor could block CCAR1/β‐catenin pathway‐mediated cancer stemness and consequently suppresses 5‐fluorouracil resistant CRC cells in vitro and in vivo.

Conclusions

Collectively, our findings reveal that DCLK1 promotes 5‐fluorouracil resistance in CRC by CCAR1/β‐catenin pathway‐mediated cancer stemness, and suggest that targeting DCLK1 might be a promising method to eliminate cancer stem cells for overcoming 5‐fluorouracil resistance in CRC.

SPINOPHILIN: a multiplayer tumor suppressor

SPINOPHILIN (SPN, PPP1R9B or NEURABIN-2) is a multifunctional protein that regulates protein-protein interactions in different cell signaling pathways. SPN is also one of the regulatory subunits of protein phosphatase 1 (PP1), implicated in the dephosphorylation of retinoblastoma protein (pRB) during cell cycle. The SPN gene has been described as a tumor suppressor in different human tumor contexts, in which low levels of SPN are correlated with a higher grade and worse prognosis. In addition, mutations of the SPN protein have been reported in human tumors. Recently, an oncogenic mutation of SPN, A566V, was described, which affects both the SPN-PP1 interaction and the phosphatase activity of the holoenzyme, and promotes p53-dependent tumorigenesis by increasing the cancer stem cell (CSC) pool in breast tumors. Thus, the loss or mutation of SPN could be late events that promotes tumor progression by increasing the CSC pool and, eventually, the malignant behavior of the tumor.

DCLK1-Short Splice Variant Promotes Esophageal Squamous Cell Carcinoma Progression via the MAPK/ERK/MMP2 Pathway

Cancer stem cell (CSC) marker doublecortin-like kinase 1 (DCLK1) contributes greatly to the malignancy of gastrointestinal cancers, and DCLK1-targeted agents have potential therapeutic value. However, the molecular pathways regulated by DCLK1-S (DCLK1 isoform 4), a shortened splice variant of DCLK1, still remain obscure. Here we found that the expression of DCLK1-S is significantly increased in human esophageal squamous cell carcinoma (ESCC) tissues and associated with malignant progression and poor prognosis. Functional studies indicated that silencing total of DCLK1 mediated by CRISPR/Cas9 inhibited ESCC cell proliferation, migration, and invasion. Conversely, these changes were largely reversed after DCLK1-S rescue or overexpression. More importantly, DCLK1-S significantly enhanced primary tumor formation and metastatic lung colonization in vivo. The Cancer Genome Atlas database and molecular analysis showed that DCLK1-S was closely related to the epithelial-mesenchymal transition (EMT) process in patients with ESCC. Further RNA sequencing and Kyoto Encyclopedia of Genes and Genomes analysis demonstrated that MAPK signaling pathway was significantly enriched. Our in vitro study proclaimed that DCLK1-S induced MMP2 expression in ESCC cells via MAPK/ERK signaling, leading to the activation of EMT. In addition, administration of ERK1/2 blocker SCH772984 attenuated the proliferative and migratory phenotype induced by DCLK1-S. In conclusion, these findings suggest that DCLK1-S may be a key molecule in MAPK/ERK/MMP2 pathway-mediated progression of ESCC, and that it has potential as a biomarker or therapeutic target to improve outcomes in patients with ESCC. IMPLICATIONS: : DCLK1-S induces ESCC progression by activating the MAPK/ERK/MMP2 axis and may serve as a prognostic biomarker or therapeutic target for patients with ESCC.

Comprehensive Analysis and Identification of Key Driver Genes for Distinguishing Between Esophageal Adenocarcinoma and Squamous Cell Carcinoma

Background: Esophageal cancer (EC) is one of the deadliest cancers in the world. However, the mechanism that drives the evolution of EC is still unclear. On this basis, we identified the key genes and molecular pathways that may be related to the progression of esophageal adenocarcinoma and squamous cell carcinoma to find potential markers or therapeutic targets. Methods: GSE26886 were obtained from Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) among normal samples, EA, and squamous cell carcinoma were determined using R software. Then, potential functions of DEGs were determined using the Database for Annotation, Visualization and Integrated Discovery (DAVID). The STRING software was used to identify the most important modules in the protein-protein interaction (PPI) network. The expression levels of hub genes were confirmed using UALCAN database. Kaplan-Meier plotters were used to confirm the correlation between hub genes and outcomes in EC. Results: In this study, we identified 1,098 genes induced in esophageal adenocarcinoma (EA) and esophageal squamous cell carcinoma (ESCC), and 669 genes were reduced in EA and ESCC, suggesting that these genes may play an important role in the occurrence and development of EC tumors. Bioinformatics analysis showed that these genes were involved in cell cycle regulation and p53 and phosphoinositide 3-kinase (PI3K)/Akt signaling pathway. In addition, we identified 147 induced genes and 130 reduced genes differentially expressed in EA and ESCC. The expression of ESCC in the EA group was different from that in the control group. By PPI network analysis, we identified 10 hub genes, including GNAQ, RGS5, MAPK1, ATP1B1, HADHA, HSDL2, SLC25A20, ACOX1, SCP2, and NLN. TCGA validation showed that these genes were present in the dysfunctional samples between EC and normal samples and between EA and ESCC. Kaplan-Meier analysis showed that MAPK1, ACOX1, SCP2, and NLN were associated with overall survival in patients with ESCC and EA. Conclusions: In this study, we identified a series of DEGs between EC and normal samples and between EA and ESCC samples. We also identified 10 key genes involved in the EC process. We believe that this study may provide a new biomarker for the prognosis of EA and ESCC.