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Abstract Background Tandem C2 domains, nuclear (TC2N) is a C2 domain-containing protein that belongs to the carboxyl-terminal type (C-type) tandem C2 protein family, and acts as an oncogenic driver in several cancers. Previously, we preliminarily reported that TC2N mediates the PI3K-Akt signaling pathway to inhibit tumor growth of breast cancer (BC) cells. Beyond that, its precise biological functions and detailed molecular mechanisms in BC development and progression are not fully understood. Methods Tumor tissues of 212 BC patients were subjected to tissue microarray and further assessed the associations of TC2N expression with pathological parameters and FASN expression. The protein levels of TC2N and FASN in cell lines and tumor specimens were monitored by qRT-PCR, WB, immunofluorescence and immunohistochemistry. In vitro cell assays, in vivo nude mice model was used to assess the effect of TC2N ectopic expression on tumor metastasis and stemness of breast cancer cells. The downstream signaling pathway or target molecule of TC2N was mined using a combination of transcriptomics, proteomics and lipidomics, and the underlying mechanism was explored by WB and co-IP assays. Results Here, we found that the expression of TC2N remarkedly silenced in metastatic and poorly differentiated tumors. Function-wide, TC2N strongly inhibits tumor metastasis and stem-like properties of BC via inhibition of fatty acid synthesis. Mechanism-wise, TC2N blocks neddylated PTEN-mediated FASN stabilization by a dual mechanism. The C2B domain is crucial for nuclear localization of TC2N, further consolidating the TRIM21-mediated ubiquitylation and degradation of FASN by competing with neddylated PTEN for binding to FASN in nucleus. On the other hand, cytoplasmic TC2N interacts with import proteins, thereby restraining nuclear import of PTEN to decrease neddylated PTEN level. Conclusions Altogether, we demonstrate a previously unidentified role and mechanism of TC2N in regulation of lipid metabolism and PTEN neddylation, providing a potential therapeutic target for anti-cancer.

Identification of cytotoxic T lymphocyte (CTL) epitopes from tumor related antigens is a promising approach for malignant tumor immunotherapy. TC2N, a recently identified tumor associated antigen from human glioblastoma, is regarded as a promising target of tumor-specific immunotherapy. As one of the most widely used histocompatibility molecules in Chinese is HLA-Ap0201, we were able to identify the TC2N peptides that are provided by this molecular type. A panel of antigenic peptides produced from TC2N were predicted by using a computer tool. The binding affinities of three peptides with the highest predicted score to the HLA-Ap0201 molecule were evaluated after synthesis. In vitro and in vivo stimulation of the main T-cell response against the predicted peptides. The results demonstrated that TC2N (152-160) was able to release IFN-? and lyse U251 cells in vitro as well as in vivo by eliciting peptide-specific CTLs. Our results indicated that peptide TC2N (152-160) (RLYGSVCDL) was a novel HLA-A2.1-restricted CTL epitope capable of inducing TC2N specific CTLs in vitro. As TC2N might qualify as a viable target for immunotherapeutic approaches for patients with GBM, we speculated that the newly identified epitope RLYGSVCDL would be of potential use in peptide-based, cancer-specific immunotherapy against GBM. [ABSTRACT FROM AUTHOR]

Background: Tandem C2 domains, nuclear (TC2N) is a C2 domain-containing protein that belongs to the carboxyl-terminal type (C-type) tandem C2 protein family, and acts as an oncogenic driver in several cancers. Previously, we preliminarily reported that TC2N mediates the PI3K-Akt signaling pathway to inhibit tumor growth of breast cancer (BC) cells. Beyond that, its precise biological functions and detailed molecular mechanisms in BC development and progression are not fully understood. Methods: Tumor tissues of 212 BC patients were subjected to tissue microarray and further assessed the associations of TC2N expression with pathological parameters and FASN expression. The protein levels of TC2N and FASN in cell lines and tumor specimens were monitored by qRT-PCR, WB, immunofluorescence and immunohistochemistry. In vitro cell assays, in vivo nude mice model was used to assess the effect of TC2N ectopic expression on tumor metastasis and stemness of breast cancer cells. The downstream signaling pathway or target molecule of TC2N was mined using a combination of transcriptomics, proteomics and lipidomics, and the underlying mechanism was explored by WB and co-IP assays. Results: Here, we found that the expression of TC2N remarkedly silenced in metastatic and poorly differentiated tumors. Function-wide, TC2N strongly inhibits tumor metastasis and stem-like properties of BC via inhibition of fatty acid synthesis. Mechanism-wise, TC2N blocks neddylated PTEN-mediated FASN stabilization by a dual mechanism. The C2B domain is crucial for nuclear localization of TC2N, further consolidating the TRIM21-mediated ubiquitylation and degradation of FASN by competing with neddylated PTEN for binding to FASN in nucleus. On the other hand, cytoplasmic TC2N interacts with import proteins, thereby restraining nuclear import of PTEN to decrease neddylated PTEN level. Conclusions: Altogether, we demonstrate a previously unidentified role and mechanism of TC2N in regulation of lipid metabolism and PTEN neddylation, providing a potential therapeutic target for anti-cancer. [ABSTRACT FROM AUTHOR]

Objective To investigate the effect and mechanism of TC2N in skin cutaneous melanoma (SKCM). Methods Using the Human Protein Atlas (HPA) and The Cancer Genome Atlas (TCGA) databases to analyze the expression and correlation of clinicopathologic feature of TC2N in SKCM. Human melanoma A375 cells were used to construct an overexpression cell model of TC2N. CCK-8 assay method was used to detect the effect of TC2N on cell proliferation. Cutaneous melanin xenograft model was constructed in TC2N knockout mice, and the tumor growth was observed and measured. Based on the animal model, the expression of Ki67 was detected in transplanted tumor by immunohistochemistry to analyze the proliferation of tumor cells. In addition, Gene Set Enrichment Analysis (GSEA) was performed to investigate the correlation between TC2N expression and ERK/MAPK signaling pathway. RT-qPCR and Western blot assay were used to detect mRNA and protein expression levels of related genes(CyclinD1, c-Myc, CDK2 and CyclinE1 in vitro and in vivo). Results Compared with normal skin tissues, the expression level of TC2N protein in SKCM tissues was higher, which was significantly associated with clinicopathological stages and lymphatic node metastasis in patients with SKCM (P < 0.05). In vitro cell experiments demonstrated that the proliferation ability of A375 cells were significantly increased after TC2N overexpression (P < 0.05). The results of skin melanin xenograft model of knockout mouse revealed that compared with TC2N+/+ mice, the tumor weight and tumor volume of TC2N-/- mice were significantly decreased (P < 0.05), suggesting that TC2N knockout significantly inhibited the growth of SKCM. GSEA enrichment analysis indicated that TC2N was significantly correlated with MAPK signaling pathway (P < 0.01), and TC2N was positively correlated with ERK/MAPK downstream gene expression (all P < 0.01). Experiments in vivo and in vitro showed TC2N expression significantly promoted the expression of ERK and p-ERK, and exerted effect on the mRNA and protein expression levels of ERK-related molecues, CyclinD1, c-Myc, CDK2 and CyclinE1(P < 0.01). Conclusion TC2N gene may promote the growth of cutaneous melanoma through activating ERK/MAPK signaling pathway.

Background: Since breast cancer is the most common type of cancer in women around theworld, finding newbiomarkers for early diagnosis of breast cancer is invaluable. Objectives: This research assessed them RNA expression of triggering receptors expressed onmyeloid cell 2 (TREM2) and tandem C2 domains nuclear protein (TC2N) genes among Iranian patients with breast cancer. Methods: We acquired 50 samples of cancerous breast tumors and corresponding adjacent non-cancerous tissues from Iranian women. The gene expression of TREM2 and TC2N wasmeasured by quantitative real-time polymerase chain reaction (q-RT-PCR). In addition, the association between TREM2 and TC2N levels with various clinicopathologic characteristics was also investigated. Results: The increased levels of TREM2 and TC2NmRNAs were shown in breast cancerous tissues in comparison with adjacent non-cancerous tissues (P < 0.05). Among the clinicopathological characteristics evaluated, tumor size, necrosis, and lymphatic tissue invasionwere significantly associatedwith high TREM2 expression. A significant relationship was also seen between increased TC2N expression and tumor grade. Sensitivity and specificity were shown at 84% and 94%, respectively, for TREM2 and 72% and 100% for TC2N. Conclusions: The data suggest that TREM2 expression, but not TC2N, could be a suitable biomarker for breast cancer diagnosis. [ABSTRACT FROM AUTHOR]

Chaihushugan san (CSS), a classic formula for soothing the liver and relieving depression, has been identified to produce rapid antidepressant-like effects in female mice. However, the gender predominance and underlying mechanisms of CSS's antidepressant remain unclear. In this study, we focused on unraveling the gender predominance of CSS in antidepressant and the specific neuronal mechanisms that mediate this predominance. Tail suspension test (TST), forced swimming test (FST) and sucrose preference test (SPT) were used to evaluate depressive phenotypes or antidepressant-like effects of CSS in female and male chronic unpredictable mild stress (CUMS) mice model. RNA-sequencing was used to screen specific target for CSS antidepressant gender dominance. RT-PCR and elisa were used to detect the expressions of specific molecule, hormones, and inflammatory factors in the hippocampus. hippocampal viral overactivation and pharmacological blockade were used to detect the correlation between CSS antidepressant gender dominance and related targets. In the present study, both female and male mice displayed depressive phenotypes including significant increasing immobility time in TST and reducing sucrose preference ratio in SPT after exposing CUMS for 3 weeks. However, acute administration of CSS (2, 4 g/kg) improved the depressive phenotypes only in female mice or not male mice at 2 h later. Moreover, the expressions of TC2N were increased only in female mice after exposing CUMS for 3 weeks, which were also reversed by CSS after a single administration 2 h later, but no alterations in male mice. The hippocampal expressions of estrogen receptor β (Erβ), pro-inflammatory factors (IL-1β and TNF-α) and anti-inflammatory factors (IL-10, TGF-β and IL-1Rα) were all abnormal in female CUMS mice model, which were all normalized by CSS. Furthermore, overactivation of hippocampal TC2N by AAV-TC2N+/+ blocked the antidepressant-like effects of CSS and the up-regulation of hippocampal Erβ in female mice. However, inhibition of Erβ blunted the antidepressant-like effects of CSS and CSS's suppression of pro-inflammatory factors (IL-1β and TNF-α), which had no any effect on hippocampal TC2N and anti-inflammatory factors (IL-10 and TGF-β). The study revealed that CSS had antidepressant superiority in female mice depending on inhibiting hippocampal TC2N and then activating Erβ, further inhibiting the release of pro-inflammatory factors to produce antidepressant effects, which provided a basis for the guidance of CSS in clinical application, new ideas and targets for the development of drugs for depression with gender differences. [Display omitted] • Chaihushugan san (CSS) had a stronger depressive effect in female mice. • Abnormal TC2N was only present in the hippocampus of female depressive model mice. • CSS was able to inhibit hippocampal TC2N and further activate Erβ. • CSS was able to activate hippocampal Erβ to inhibit pro-inflammatory factors. [ABSTRACT FROM AUTHOR]

Several C2 domain-containing proteins play key roles in tumorigenesis, signal transduction, and mediating protein–protein interactions. Tandem C2 domains nuclear protein (TC2N) is a tandem C2 domain-containing protein that is differentially expressed in several types of cancers and is closely associated with tumorigenesis and tumor progression. Notably, TC2N has been identified as an oncogene in lung and gastric cancer but as a tumor suppressor gene in breast cancer. Recently, a large number of tumor-associated antigens (TAAs), such as heat shock proteins, alpha-fetoprotein, and carcinoembryonic antigen, have been identified in a variety of malignant tumors. Differences in the expression levels of TAAs between cancer cells and normal cells have led to these antigens being investigated as diagnostic and prognostic biomarkers and as novel targets in cancer treatment. In this review, we summarize the clinical characteristics of TC2N-positive cancers and potential mechanisms of action of TC2N in the occurrence and development of specific cancers. This article provides an exploration of TC2N as a potential target for the diagnosis and treatment of different types of cancers. [ABSTRACT FROM AUTHOR]

As the most common tumor of central nervous system in adults, glioma is characterized with poor prognosis. Tac2-N (TC2N) is a newly discovered protein that play potential roles in lung cancer and breast cancer progression. Here we aimed to investigate the expression, clinical significance, and function of TC2N in glioma. The mRNA level of TC2N in glioma patients was extracted from TCGA datasets. Immunohistochemistry staining was conducted to test protein expression of TC2N in glioma tissues. Chi-square test was used to assess correlations between TC2N expression and patients' clinicopathological characteristics. Kaplan-Meier method was used to plot survival curves. The prognostic predictive role of TC2N was evaluated by univariate and multivariate analyses. Knockdown assays were performed in U87 and U251 cell lines, respectively. Cell proliferation, colony formation, and subcutaneous mice xenografts were used to reveal the tumor-related role of TC2N in glioma. Compared with normal brain tissues, the mRNA level of TC2N was significantly higher in glioma tissues, whose dysregulated higher mRNA level was correlated with poorer overall survival. Similarly, higher protein expression of TC2N was observed in cases with larger tumor size and advanced WHO grades. Univariate and multivariate analyses identified TC2N as a novel independent prognostic factor of gliomas. In vitro and in vivo data demonstrated that TC2N interference can remarkably prevent glioma cell proliferation and tumor growth. In conclusion, high TC2N expression is significantly correlated with poor overall survival of glioma patients via enhancing tumor growth. [ABSTRACT FROM AUTHOR]

Several C2 domain-containing proteins play key roles in tumorigenesis, signal transduction, and mediating protein–protein interactions. Tandem C2 domains nuclear protein (TC2N) is a tandem C2 domain-containing protein that is differentially expressed in several types of cancers and is closely associated with tumorigenesis and tumor progression. Notably, TC2N has been identified as an oncogene in lung and gastric cancer but as a tumor suppressor gene in breast cancer. Recently, a large number of tumor-associated antigens (TAAs), such as heat shock proteins, alpha-fetoprotein, and carcinoembryonic antigen, have been identified in a variety of malignant tumors. Differences in the expression levels of TAAs between cancer cells and normal cells have led to these antigens being investigated as diagnostic and prognostic biomarkers and as novel targets in cancer treatment. In this review, we summarize the clinical characteristics of TC2N-positive cancers and potential mechanisms of action of TC2N in the occurrence and development of specific cancers. This article provides an exploration of TC2N as a potential target for the diagnosis and treatment of different types of cancers.

Identification of cytotoxic T lymphocyte (CTL) epitopes from tumor related antigens is a promising approach for malignant tumor immunotherapy. TC2N, a recently identified tumor associated antigen from human glioblastoma, is regarded as a promising target of tumor-specific immunotherapy. As one of the most widely used histocompatibility molecules in Chinese is HLA-A*0201, we were able to identify the TC2N peptides that are provided by this molecular type. A panel of antigenic peptides produced from TC2N were predicted by using a computer tool. The binding affinities of three peptides with the highest predicted score to the HLA-A*0201 molecule were evaluated after synthesis. In vitro and in vivo stimulation of the main T-cell response against the predicted peptides. The results demonstrated that TC2N (152-160) was able to release IFN-γ and lyse U251 cells in vitro as well as in vivo by eliciting peptide-specific CTLs. Our results indicated that peptide TC2N (152-160) (RLYGSVCDL) was a novel HLA-A2.1-restricted CTL epitope capable of inducing TC2N specific CTLs in vitro. As TC2N might qualify as a viable target for immunotherapeutic approaches for patients with GBM, we speculated that the newly identified epitope RLYGSVCDL would be of potential use in peptide-based, cancer-specific immunotherapy against GBM.

Hepatocellular carcinoma (HCC), one of the most prevalent types of cancer worldwide, has an exceedingly poor prognosis. Tandem C2 domain nuclear protein (TC2N) has been implicated in tumorigenesis and serves as an oncogene or tumor suppressor in different types of cancer. Here, we explore the possible regulatory activities and molecular mechanisms of TC2N in HCC progression. However, TC2N expression was significantly upregulated in HCC tissues and hepatoma cell lines, and this upregulation was positively correlated with tumor progression in HCC patients. The ectopic overexpression of TC2N accelerated the proliferation, migration, and invasion of HCC cells, whereas its knockdown showed the opposite effects. Bioinformatics analysis showed that TC2N participates in the regulation of the Wnt/β-catenin signaling pathway. Mechanistically, TC2N activated the Wnt/β-catenin signaling pathway by regulating the expression levels of β-catenin and its downstream targets CyclinD1, MMP7, c-Myc, c-Jun, AXIN2, and glutamine synthase. Furthermore, the deletion of β-catenin effectively neutralized the regulation of TC2N in HCC proliferation and metastasis. Overall, this study showed that TC2N promotes HCC proliferation and metastasis by activating the Wnt/β-catenin signaling pathway, indicating that TC2N might be a potential molecular target for the treatment of HCC., (Copyright © 2023 United States & Canadian Academy of Pathology. Published by Elsevier Inc. All rights reserved.)

The regulatory mechanism of mammary gland development and lactation is important, as lactation not only provides healthy milk for infants, but also provides health benefits to mothers. Circular RNAs (circRNAs) have recently received much attention, but only a few have been functionally characterized. In the present study, the structure and expression profile of a rat Tc2n-derived circular RNA (cTc2n) was investigated by several protocols. The cTc2n comprised exons10 and 11 of the Tc2ngeneandhad no poly(A)structure. The expression of cTc2n was significantly higher in the mammary gland of rat than in other tissues, including the heart, liver, spleen, lung, kidney, uterus and ovary. The abundance of cTc2n was the highest on day 1, and significantly declined on day 7, slightly increasing on day 21 postpartum. This finding indicates that cTc2n might play an important role in lactation.

The regulatory mechanism of mammary gland development and lactation is important, as lactation not only provides healthy milk for infants, but also provides health benefits to mothers. Circular RNAs (circRNAs) have recently received much attention, but only a few have been functionally characterized. In the present study, the structure and expression profile of a rat Tc2n-derived circular RNA (cTc2n) was investigated by several protocols. The cTc2n comprised exons 10 and 11 of the Tc2n gene and had no poly(A) structure. The expression of cTc2n was significantly higher in the mammary gland of rat than in other tissues, including the heart, liver, spleen, lung, kidney, uterus and ovary. The abundance of cTc2n was the highest on day 1, and significantly declined on day 7, slightly increasing on day 21 postpartum. This finding indicates that cTc2n might play an important role in lactation. [ABSTRACT FROM AUTHOR]

As the most common tumor of central nervous system in adults, glioma is characterized with poor prognosis. Tac2-N (TC2N) is a newly discovered protein that play potential roles in lung cancer and breast cancer progression. Here we aimed to investigate the expression, clinical significance, and function of TC2N in glioma. The mRNA level of TC2N in glioma patients was extracted from TCGA datasets. Immunohistochemistry staining was conducted to test protein expression of TC2N in glioma tissues. Chi-square test was used to assess correlations between TC2N expression and patients' clinicopathological characteristics. Kaplan-Meier method was used to plot survival curves. The prognostic predictive role of TC2N was evaluated by univariate and multivariate analyses. Knockdown assays were performed in U87 and U251 cell lines, respectively. Cell proliferation, colony formation, and subcutaneous mice xenografts were used to reveal the tumor-related role of TC2N in glioma. Compared with normal brain tissues, the mRNA level of TC2N was significantly higher in glioma tissues, whose dysregulated higher mRNA level was correlated with poorer overall survival. Similarly, higher protein expression of TC2N was observed in cases with larger tumor size and advanced WHO grades. Univariate and multivariate analyses identified TC2N as a novel independent prognostic factor of gliomas. In vitro and in vivo data demonstrated that TC2N interference can remarkably prevent glioma cell proliferation and tumor growth. In conclusion, high TC2N expression is significantly correlated with poor overall survival of glioma patients via enhancing tumor growth.

Background: Tac2-N (TC2N) is a tandem C2 domain-containing protein, acting as a novel oncogene or suppressor in different kinds of cancers. However, the status of TC2N expression and its significance in gastric cancer (GC) is still unclear. The present study is aimed to elucidate the clinicopathological significance and prognostic value of TC2N level in GC. Methods: We used sequencing data from the Cancer Genome Atlas (TCGA) database to analyze TC2N expression in GC by UALCAN database and Gene Expression Profiling Interactive Analysis tools (GEPIA). TC2N expression level in 12 pairs of fresh GC tissues and adjacent nontumorous tissues was detected by quantitative real-time reverse-transcription polymerase chain reaction (RT-PCR) and Western blot (WB) assays. Immunohistochemical (IHC) staining was used to detect TC2N protein expression in Paraffin-embedded tissues in our center. In vitro proliferation, migration and invasion assays were used to evaluate the effect of TC2N on functional capability of gastric cancer cells. LinkedOmics was used to identify gene expressions associated with TC2N . Results: The mRNA and protein expression of TC2N in gastric cancer were both significantly higher than normal gastric mucosa. It was also elevated in gastric cancer cells compared with normal gastric epithelium cell. In vitro assays suggested that TC2N facilitated proliferation, migration and invasion of gastric cancer cells. Bioinformatic analysis showed a widespread impact of TC2N on the transcriptome and a strong interaction with tumor associated genes. We also found that TC2N was an independent prognostic factor for long-term survival in GC patients and its high expression was evidently associated with poor overall survival and recurrence-free survival. Conclusions: Our results show that high level of TC2N correlates with poor prognosis in patients with gastric cancer and promotes the development of gastric cancer. Thus, TC2N expression can serve as a prognostic biomarker for patients with gastric cancer., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Background: Role of TC2N in carcinogenesis has been largely unfathomed until recently when it was identified as a novel oncogene in lung cancer. Subsequently, a tumour suppressor role of TC2N was reported in breast cancer. It is therefore highly relevant to investigate TC2N molecular partners/mechanisms on a larger scale including a wider range of tumour types., Methods: We investigated TC2N mRNA expression, its promoter methylation levels, effects of TC2N transcription on overall patient survival, somatic mutations in TC2N gene and correlation between TC2N mRNA expression and other cancer genes in pan-cancer by using data available from the Cancer Genome Atlas (TCGA) and the Genotype Tissue Expression (GTEx) databases., Results: TC2N mRNA expression was differentially regulated in 9/33 TCGA tumour types. Of these 9 tumours, 5 tumour types (cholangiocarcinoma, ovarian-serous-cystadenocarcinoma, rectal-adenocarcinoma, stomach-adenocarcinoma and thymoma) had significantly higher TC2N mRNA expression while 4 (pheochromocytoma-and-paraganglioma, skin-cutaneous-melanoma, thyroid-carcinoma and uterine-carcinosarcoma) had significantly lower TC2N mRNA expression compared to matched and normal controls. TC2N promoter was hypermethylated in most cancers while hypomethylated in head-and-neck-squamous-cell-carcinoma and kidney-renal-clear-cell carcinoma. TC2N transcription was positively correlated with transcription of several other cancer genes including genes from Myc, cell-cycle, Nrf2, Wnt, PI3K, Hippo, Notch, TGFβ and RAS/RTK pathways. Poor prognosis was associated with higher TC2N mRNA levels in pancreatic-adenocarcinoma and brain-lower-grade-glioma and lower TC2N mRNA levels in kidney-renal-clear-cell-carcinoma, mesothelioma, sarcoma and skin-cutaneous melanoma. Functional protein partners of TC2N were identified as STX2, SMEK1, SMEK2, STXBP5, SCARA5, MMRN1, CATSPER2, CATSPERB, CLEC4M and STAB2. Many of these proteins are key players in carcinogenesis of various cancers. Highest pathogenic somatic mutation rates in TC2N were found in skin-cutaneous-melanoma, uterine-corpus-endometrial-carcinoma, colon-endocervical-adenocarcinoma, bladder-urothelial-carcinoma and breast-invasive-carcinoma., Conclusion: Our findings unravel several un-explored avenues related to the role of TC2N in tumourigenesis of several cancers, suggesting TC2N as an important player and a potential candidate for tumour-therapy.