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Published on: October 27, 2014
TC2N maintains stem cell-like characteristics to accelerate lung carcinogenesis by blockade of dual specificity
Jing Gu1, Yang-Fan Lv2, Ji-Ying Xia2
1Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing, 400038, PR China.
Background:
Tandem C2 domains, nuclear (TC2N) is a protein that has been characterized to contain C2A domain, C2B domain, and a short C-terminus with a WHXL motif. In previous studies, we have uncovered the oncogenic role and mechanisms of TC2N in lung cancer: TC2N achieves this by inhibiting the p53 signaling pathway and activating the NF-kappaB signaling pathway. Beyond that, its precise function in tumorigenesis is not fully understood.
Methods:
TC2N-engineered mice model was used to assess the effect of TC2N knockout on normal lung and urethane-induced carcinogenesis. Tumor tissues of 395 lung cancer patients were subjected to tissue microarray and further assessed the associations of TC2N expression with tumor differentiation degree. The protein levels of TC2N and stem cell markers in cell lines and tissue specimens were monitored by WB and immunohistochemistry. In vitro cell assays were performed to assess the effect of TC2N ectopic expression on the stem cell-like characteristics of lung cancer cells. The downstream signaling pathway or target molecule of TC2N was mined using a combination of transcriptomics and proteomics, and the underlying mechanism was explored by WB and co-IP assays.
Results:
Herein, TC2N appeared to have a strong effect in promoting lung tumorigenesis caused by urethane, whereas it seemed to lose its function in the normal lung. Meanwhile, we found that the functional differences of TC2N between lung tumor and normal lung were linked to its potential role in cancer cell stemness. Function-wise, TC2N overexpression maintained stem-like properties of lung cancer cell. Mechanism-wise, TC2N upregulated the phosphorylation of EGFR, ERK, STAT3 and FAK1 to activate these signaling pathways by the inhibition of DUSP3 phosphatase via a dual mechanism. Firstly, TC2N competes with EGFR, ERK, STAT3 and FAK1 for binding to DUSP3. This competition prevents these signaling molecules from being dephosphorylated by DUSP3, resulting in their sustained activation. Secondly, TC2N bind to DUSP3 and restrict the enzyme's ability to dephosphorylate the signaling molecules.
Conclusions:
Overall, this study revealed a previously unknown role and mechanism of TC2N in the regulation of tumorigenesis and stemness in lung cancer cells.
Insights
Tandem C2 domains, nuclear (TC2N) protein promotes lung cancer by maintaining cancer stemness. It activates key signaling pathways by inhibiting DUSP3 phosphatase, revealing a novel mechanism in tumorigenesis.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Research
Background:
- Tandem C2 domains, nuclear (TC2N) is implicated in lung cancer, potentially through p53 and NF-kappaB pathways.
- Its precise role in tumorigenesis and cancer stemness remains incompletely understood.
Purpose of the Study:
- To elucidate the function and mechanism of TC2N in lung cancer development and progression.
- To investigate the link between TC2N, lung tumorigenesis, and cancer cell stemness.
Main Methods:
- Utilized TC2N-engineered mice models for assessing knockout effects on normal lung and carcinogenesis.
- Analyzed lung cancer patient tissues (n=395) for TC2N expression correlation with differentiation.
- Employed Western blot, immunohistochemistry, cell assays, transcriptomics, proteomics, and co-IP to explore TC2N's mechanisms.
Main Results:
- TC2N significantly promotes urethane-induced lung tumorigenesis but has minimal effect on normal lung tissue.
- TC2N overexpression maintains stem-like properties in lung cancer cells.
- TC2N upregulates EGFR, ERK, STAT3, and FAK1 signaling by inhibiting DUSP3 phosphatase through competitive binding and restricted dephosphorylation.
Conclusions:
- TC2N plays a critical role in regulating lung cancer stemness and tumorigenesis.
- TC2N's mechanism involves the dual inhibition of DUSP3 phosphatase, leading to sustained activation of oncogenic signaling pathways.
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