Nucleus Accumbens-associated Protein 1 Research Articles

Co-Targeting Nucleus Accumbens Associate 1 and NF-κB Signaling Synergistically Inhibits Melanoma Growth.

Nucleus-accumbens-associated protein-1 (NAC1) is a cancer-related transcriptional factor encoded by the NACC1 gene, which is amplified and overexpressed in various human cancers and has been appreciated as one of the top potential cancer driver genes. NAC1 has therefore been explored as a potential therapeutic target for managing malignant tumors. Here, we show that NAC1 is a negative regulator of NF-κB signaling, and NAC1 depletion enhances the level of the nuclear NF-κB in human melanoma. Furthermore, the inhibition of NF-κB signaling significantly potentiates the antineoplastic activity of the NAC1 inhibition in both the cultured melanoma cells and xenograft tumors. This study identifies a novel NAC1-NF-κB signaling axis in melanoma, offering a promising new therapeutic option to treat melanoma.

Identification of a NACC1-Regulated Gene Signature Implicated in the Features of Triple-Negative Breast Cancer.

Triple-negative breast cancer (TNBC), characterized by a deficiency in estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor2 (HER2), is among the most lethal subtypes of breast cancer (BC). Nevertheless, the molecular determinants that contribute to its malignant phenotypes such as tumor heterogeneity and therapy resistance, remain elusive. In this study, we sought to identify the stemness-associated genes involved in TNBC progression. Using bioinformatics approaches, we found 55 up- and 9 downregulated genes in TNBC. Out of the 55 upregulated genes, a 5 gene-signature (CDK1, EZH2, CCNB1, CCNA2, and AURKA) involved in cell regeneration was positively correlated with the status of tumor hypoxia and clustered with stemness-associated genes, as recognized by Parametric Gene Set Enrichment Analysis (PGSEA). Enhanced infiltration of immunosuppressive cells was also positively correlated with the expression of these five genes. Moreover, our experiments showed that depletion of the transcriptional co-factor nucleus accumbens-associated protein 1 (NAC1), which is highly expressed in TNBC, reduced the expression of these genes. Thus, the five genes signature identified by this study warrants further exploration as a potential new biomarker of TNBC heterogeneity/stemness characterized by high hypoxia, stemness enrichment, and immune-suppressive tumor microenvironment.

Abstract 2327: Novel role of NAC1 in regulating tumor stem cells and their interaction with immune cells in triple-negative breast cancer

Abstract One of the important features of triple-negative breast cancer (TNBC) is the enrichment of stem-like cells that contribute substantially to the malignant phenotype. Nucleus accumbens associated protein 1 (NAC1), a unique member of the BTB-POZ family, is implicated in tumor development and progression of various types of cancer. The objective of this study was to test the hypothesis that NAC1 plays a critical role in maintaining stemness of TNBC. We found that TNBC cell lines, MDA-MB-231 and HCC-1806, had high NAC1 expressions compared to normal. Hematoxylin-eosin staining of 450 human breast cancer tissues revealed high NAC1 expressions in different stages of breast tumor development. Depletion of NAC1 in TNBC cells decreased their mammosphere formation, migration and invasion abilities, and altered their EMT phenotype. Canonical TNBC stemness markers CD44 and ALDH1A1 were downregulated in TNBC cells subjected to NAC1 depletion. Down-regulation of NAC1 also decreased aldolase activity. RNA sequencing uncovered the enrichment of JAK/STAT3, PI3K/AKT, WNT, stemness and tumor progression-associated genes in TNBC with depletion of NAC1. IHC analysis revealed increased expression of phospho-STAT3 (Y705), β-catenin, PDK1, cyclin D1, cMYC, IL-6 and phosphorylated PTEN in TNBC cells in support of the sequencing data. Immunoprecipitation assays demonstrated the physical association of NAC1 with STAT3 and CD44 and the pulse-chase experiments showed that the proteasome-mediated turnover of STAT3 was faster in the NAC1-depleted cells than the control cells (half-life: 5hrs vs 24hrs, respectively). NAC1-depleted cells had a significantly reduced tumorigenic ability in vivo. TCGA immune cell infiltration analysis revealed that NAC1 expression had a positive correlation with myeloid-derived suppressor cells (MDSCs) infiltration. In vitro co-culture assays with Gr1/CD11b+ cells from NAC1 knockout mice with EO771 tumor cells showed increase of the stemness marker CD44 and aldolase activity, suggesting a role of NAC1 in modulating the stemness-immune interaction in tumor microenvironment. Further, we observed a significant increase of NAC1 in MDSCs from the tumor bearing mice compared to that of the tumor-free mice. The results of this study demonstrate a novel role of NAC1 in regulating tumor stem cells and their crosstalk with immune cells in the tumor microenvironment (TME) and suggest that targeting NAC1 may be exploited as a new approach to reverse immune-suppressive TME and to improve treatment for TNBC. Citation Format: Chrispus M. Ngule, Hami Hemati, Xingcong Ren, Emily Bachert, Xiaoqi Liu, Jin-Ming Yang. Novel role of NAC1 in regulating tumor stem cells and their interaction with immune cells in triple-negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2327.

Mechanistic insights of NAC1 nuclear export and its role in ovarian cancer resistance to docetaxel

In this study, we uncovered the nuclear export of nucleus accumbens-associated protein-1 (NAC1) as a novel mechanism involved in ovarian cancer resistance to taxanes, the chemotherapeutic drugs commonly used in treatment of this malignancy. We showed that NAC1, a nuclear factor of the BTB/POZ gene family, has a nuclear export signal (NES) at the N terminus (aa 17–28), and this NES critically contributes to the NAC1 nuclear-cytoplasmic shuttling when tumor cells were treated with docetaxel. Mechanistically, the nuclear-exported NAC1 bound to cullin3 (Cul3) and Cyclin B1 via its BTB and BOZ domains respectively, and the cyto-NAC1-Cul3 E3 ubiquitin ligase complex promotes the ubiquitination and degradation of Cyclin B1, thereby facilitating mitotic exit and leading to cellular resistance to docetaxel. We also showed in in vitro and in vivo experiments that TP-CH-1178, a membrane-permeable polypeptide against the NAC1 NES motif, blocked the nuclear export of NAC1, interfered with the degradation of Cyclin B1 and sensitized ovarian cancer cells to docetaxel. This study not only reveals a novel mechanism by which the NAC1 nuclear export is regulated and Cyclin B1 degradation and mitotic exit are impacted by the NAC1-Cul3 complex, but also provides the nuclear-export pathway of NAC1 as a potential target for modulating taxanes resistance in ovarian cancer and other malignancies.

Tumorous expression of NAC1 restrains antitumor immunity through the LDHA-mediated immune evasion

BackgroundT cell-mediated antitumor immunity has a vital role in cancer prevention and treatment; however, the immune-suppressive tumor microenvironment (TME) constitutes a significant contributor to immune evasion that weakens antitumor immunity....

Expression of NAC1 Restrains the Memory Formation of CD8+ T Cells during Viral Infection.

Nucleus accumbens-associated protein 1 (NAC1) is a transcription co-factor that has been shown to possess multiple roles in stem cell and cancer biology. However, little is known about its roles in regulation of the immune system. In the current study, we observed that expression of NAC1 impacted the survival of CD8+ T cells in vitro. NAC1−/− CD8+ T cells displayed lower metabolism, including reduced glycolysis and oxidative phosphorylation. In vivo, compared with wild-type (WT) mice, NAC1−/− mice produced a lower response to vaccinia virus (VACV) infection, and viral antigen (Ag)-specific CD8+ T cells decreased more slowly. Additionally, we observed that the NAC1−/− mice demonstrated a stronger memory formation of viral Ag-specific CD8+ T cells post-viral infection. Mechanically, we identified that compared with WT CD8+ T cells, the Interferon Regulatory Factor 4 (IRF4), a key transcription factor in T cell development, was highly expressed in NAC1−/− CD8+ T cells, insinuating that IRF4 could be a critical regulatory target of NAC1 in the memory formation of CD8+ T cells. Our results indicate that NAC1 restrains the memory formation of CD8+ T cells by modulating IRF4, and targeting NAC1 may be exploited as a new approach to boosting CD8+ T cell memory.

NAC1 modulates autoimmunity by suppressing regulatory T cell-mediated tolerance.

We report here that nucleus accumbens–associated protein-1 (NAC1), a nuclear factor of the Broad-complex, Tramtrack, Bric-a-brac/poxvirus and zinc finger (BTB/POZ) gene family, is a negative regulator of FoxP3 in regulatory T cells (Tregs) and a critical determinant of immune tolerance. Phenotypically, NAC1−/− mice showed substantial tolerance to the induction of autoimmunity and generated a larger amount of CD4+ Tregs that exhibit a higher metabolic profile and immune-suppressive activity, increased acetylation and expression of FoxP3, and slower turnover of this transcription factor. Treatment of Tregs with the proinflammatory cytokines interleukin-1β or tumor necrosis factor–α induced a robust up-regulation of NAC1 but evident down-regulation of FoxP3 as well as the acetylated FoxP3. These findings imply that NAC1 acts as a trigger of the immune response through destabilization of Tregs and suppression of tolerance induction, and targeting of NAC1 warrants further exploration as a potential tolerogenic strategy for treatment of autoimmune disorders.

Tumoral Expression of NAC1 Restrains Antitumor Immunity through the LDHA-mediated Immune Evasion

Abstract T cell-mediated antitumor immunity has an important role in cancer prevention and treatment; however, immunosuppressive tumor microenvironment (TME) constitutes a major contributor to immune evasion that weakens antitumor immunity. We report here that tumoral expression of nucleus accumbens-associated protein-1 (NAC1), a nuclear factor of the broad complex, tramtrack, bric-a-brac/poxvirus and zinc finger (BTB/POZ) gene family, negatively impacts the CD8+ T cell - mediated antitumor immunity via through LDHA-mediated suppressive tumor microenvironment. We show that NAC1 could positively regulate the expression of lactate dehydrogenase A (LDHA) at transcriptional level, and LDHA-mediated lactic acid accumulation only inhibited cytokine production but also induced the exhaustion and apoptosis of CD8+ cytotoxic T lymphocytes (CTLs), impairing their cell-killing ability. We further show that in the immunocompetent and immunodeficient mice bearing melanoma, tumors with NAC1 depletion grew significantly slower and had elevated infiltration of tumor antigen specific CTLs following adoptive cell transfer, as compared with the control groups. These findings imply that tumor expression of NAC1 contributes substantially to immune evasion through its regulatory role in LDHA expression and lactic production. Thus, therapeutic targeting of NAC1 warrants further exploration as a potential strategy to reinforce cancer immunotherapy such as adoptive cell transfer of CTLs.

Activating transcription factor 3-activated long noncoding RNA forkhead box P4-antisense RNA 1 aggravates colorectal cancer progression by regulating microRNA-423-5p/nucleus accumbens associated 1 axis

ABSTRACT Long noncoding RNAs (lncRNAs) have vital roles in the progression of colorectal cancer (CRC). Forkhead box P4-antisense RNA 1 (FOXP4-AS1) showed a potential unfavorable prognostic factor for CRC, while its underlying mechanism remains elusive. Thus, the goal of this research is to determine mechanism of FOXP4-AS1 in CRC occurrence and development. Herein, a Dual-luciferase reporter assay was performed to assess the regulation of miR-423-5p to nucleus accumbens-associated protein 1 (NACC1) and activating transcription factor 3 (ATF3) to FOXP4-AS1 promoter. Hematoxylin-eosin (H&E) staining was performed to detect the pathological changes of tumor tissues. Flow cytometry, cell counting kit 8, Transwell, and wound healing assays were conducted to assess apoptosis, proliferation, migration, and invasion of CRC cells, respectively. The results showed that FOXP4-AS1 was highly expressed in CRC cell lines and tissues. CRC progression was promoted by the overexpression of FOXP4-AS1 in HTC116 cells and animal models. Furthermore, FOXP4-AS1 served as a molecular sponge for miR-423-5p, and NACC1 is a direct target of miR-423-5p. MiR-423-5p silencing or overexpression of NACC1 increased proliferation, migration, and invasion of HCT116 cells while suppressing apoptosis. We also found that the upregulation of FOXP4-AS1 was activated by ATF3 in CRC cells. Collectively, our results demonstrated that ATF3-activated FOXP4-AS1 aggravates CRC progression by regulating miR-423-5p/NACC1 axis, indicating a new target for CRC treatment.

Silencing of NACC1 inhibits the proliferation, migration and invasion of nasopharyngeal carcinoma cells via regulating the AKT/mTOR signaling pathway.

Nucleus accumbens-associated protein 1 (NACC1) has been reported to serve as an oncogenic role in several types of cancer; however, its role in nasopharyngeal carcinoma (NPC) remains to be determined. The present study aimed to investigate the role of NACC1 in NPC and elucidate the underlying mechanisms. Therefore, NACC1 expression in the normal nasopharyngeal epithelial cell line, NP69, and various NPC cell lines was determined by reverse transcription-quantitative PCR and western blot analyses. NACC1 expression was silenced in the NPC SUNE-1 cell line by transfection with a short hairpin RNA. Cell viability, proliferation, migration, invasion and epithelial-mesenchymal transition (EMT) were then evaluated using MTT, colony formation, wound healing, Transwell and western blot assays, respectively. SC79 was employed to activate AKT expression in NACC1-silenced SUNE-1 cells, and the aforementioned cellular processes were observed. The results revealed that NACC1 expression was upregulated in NPC cell lines. NACC1-knocdown inhibited SUNE-1 cell proliferation, migration, invasion and EMT. Moreover, the levels of phosphorylated AKT and mTOR were decreased upon NACC1 silencing. Mechanistically, the presence of SC79 significantly blocked all the effects of NACC1-knockdown on SUNE-1 cells. The findings of the present study demonstrated that NACC1-knockdown effectively suppressed NPC cell proliferation, migration and invasion by inhibiting the activation of the AKT/mTOR signaling pathway. NACC1 may thus serve as a potential target for the diagnosis and therapy of NPC.

Circ_0027089 regulates NACC1 by targeting miR-136-5p to aggravate the development of hepatitis B virus-related hepatocellular carcinoma.

Hepatitis B virus (HBV) infection is the main trigger of hepatocellular carcinoma (HCC). Circular RNA plays an indispensable role in cancer development, and this study aimed to disclose the function and mechanism of circ_0027089 in HBV-related HCC. The expression levels of circ_0027089, miR-136-5p and nucleus accumbens associated protein 1 (NACC1) mRNA were measured by quantitative real-time PCR, and the protein level of NACC1 was detected by western blot. For functional analyses, cell proliferation was assessed by cell counting kit-8 assay and colony formation assay. Cell apoptosis and cell cycle were detected by flow cytometry assay, and cell apoptosis was also assessed by caspase 3/7 activity. The capacities of migration and invasion were evaluated by wound healing assay and transwell assay, respectively. The predicted relationship between miR-136-5p and circ_0027089 or NACC1 was validated by dual-luciferase reporter assay and RNA binding protein immunoprecipitation assay. Animal experiments were performed in nude mice to explore the role of circ_0027089 in vivo. Circ_0027089 expression and NACC1 expression were elevated, while miR-136-5p expression was decreased in HBV-related HCC tissues and cells. In function, circ_0027089 knockdown inhibited HepG2.2.15 and HepAD38 (tet-off) cell proliferation, migration and invasion but induced cell cycle arrest and apoptosis, while circ_0027089 overexpression played the reversed effects. For mechanism exploration, miR-136-5p was a target of circ_0027089, and miR-136-5p deficiency could reverse the role of circ_0027089 knockdown. Circ_0027089 functioned as an oncogene to promote the development of HBV-related HCC by regulating NACC1 via competitively targeting miR-136-5p.

Nucleus Accumbens-Associated Protein 1 Binds DNA Directly through the BEN Domain in a Sequence-Specific Manner.

Nucleus accumbens-associated protein 1 (NAC1) is a nuclear protein that harbors an amino-terminal BTB domain and a carboxyl-terminal BEN domain. NAC1 appears to play significant and diverse functions in cancer and stem cell biology. Here we demonstrated that the BEN domain of NAC1 is a sequence-specific DNA-binding domain. We selected the palindromic 6 bp motif ACATGT as a target sequence by using a PCR-assisted random oligonucleotide selection approach. The interaction between NAC1 and target DNA was characterized by gel shift assays, pull-down assays, isothermal titration calorimetry (ITC), chromatin-immunoprecipitation assays, and NMR chemical shifts perturbation (CSP). The solution NMR structure revealed that the BEN domain of human NAC-1 is composed of five conserved α helices and two short β sheets, with an additional hitherto unknown N-terminal α helix. In particular, ITC clarified that there are two sequential events in the titration of the BEN domain of NAC1 into the target DNA. The ITC results were further supported by CSP data and structure analyses. Furthermore, live cell photobleaching analyses revealed that the BEN domain of NAC1 alone was unable to interact with chromatin/other proteins in cells.

Systemic Delivery of NAC-1 siRNA by Neuropilin-Targeted Polymersomes Sensitizes Antiangiogenic Therapy of Metastatic Triple-Negative Breast Cancer.

Antiangiogenic therapy with bevacizumab while being interesting for metastatic triple-negative breast cancer (mTNBC) is restrained by tumor hypoxia elevation and cancer stem cell enrichment. Here, we find that neuropilin-1 (NRP-1)-targeted delivery of nucleus accumbens-associated protein-1 (NAC-1) siRNA mediated by tLyP-1 peptide-functionalized chimaeric polymersomes (tLyP-1-Ps) effectively sensitizes antiangiogenic therapy of mTNBC in vivo. tLyP-1-Ps showed good encapsulation (up to 14.4 wt. %) of siNAC-1, giving robust tLyP-1-Ps-siNAC-1 nanoformulation with a defined size of 48.5 nm (PDI = 0.13) and a surface charge of -9.2 mV, and mediated efficient cytoplasmic transportation of siNAC-1 in MDA-MB-231 TNBC cells, resulting in significant silencing of NAC-1 mRNA and the corresponding oncoprotein. Transwell invasion and wound healing assays revealed that tLyP-1-Ps-siNAC-1 potently inhibited MDA-MB-231 cell invasion and migration. Intriguingly, tLyP-1-Ps-siNAC-1 was shown to markedly improve the bevacizumab therapy of mTNBC, significantly curbing lung metastasis and prolonging the survival time of the MDA-MB-231 metastatic model. The combination of targeted NAC-1 gene silencing and antiangiogenic therapy appears to be an innovative treatment for mTNBC.

Circular RNA hsa_circ_0001588 promotes the malignant progression of lung adenocarcinoma by modulating miR-524-3p/NACC1 signaling

AimsPrevious studies have demonstrated that circular RNAs play significant roles in several tumors, including lung adenocarcinoma; however, specific biological functions and molecular mechanisms underlying this process remain unclear. Materials and methodsHere, we conducted real-time quantitative PCR (qRT-PCR) to measure hsa_circ_0001588 expression levels in 60 paired lung adenocarcinoma tissues and cell lines. Furthermore, the association between hsa_circ_0001588 and clinical features of lung adenocarcinoma was analyzed. Functional experiments were conducted to assess the influence of hsa_circ_0001588 on proliferation, migration, and invasion in lung adenocarcinoma cells. We detected possible downstream targets of hsa_circ_0001588 using bioinformatics analysis. Luciferase reporter assays, qRT-PCR, and western blotting assays were performed to verify the molecular mechanism underlying hsa_circ_0001588 functions. Key findingsWe found that hsa_circ_0001588 was prominently upregulated in lung adenocarcinoma tissues and cell lines; elevated expression of hsa_circ_0001588 was positively correlated with poor clinicopathological features of lung adenocarcinoma. Functional experiments revealed that hsa_circ_0001588 acts as an oncogene to promote the proliferation, migration, and invasion of lung adenocarcinoma in vitro. Mechanistically, hsa_circ_0001588 promoted the proliferation, migration, and metastasis of lung adenocarcinoma by binding to miR-524-3p to promote nucleus accumbens-associated protein 1(NACC1) expression.Significance: Together, our results revealed that hsa_circ_0001588 upregulated the expression of NACC1 by combining with miR-524-3p to promote the proliferation, migration, and invasion of lung adenocarcinoma cells, suggesting that hsa_circ_0001588 may be an underlying therapeutic target for lung adenocarcinoma.

NAC1 attenuates BCL6 negative autoregulation and functions as a BCL6 coactivator of FOXQ1 transcription in cancer cells.

Background: Nucleus accumbens-associated protein 1 (NAC1) has multifaceted roles in cancer pathogenesis and progression, including the development of drug resistance, promotion of cytokinesis, and maintenance of “stem cell-like” phenotypes. NAC1 is a transcriptional co-regulator belonging to the bric-a-brac tramtrack broad (BTB) family of proteins, although it lacks the characteristic DNA binding motif of the BTB family. The formation of higher-order transcription complexes likely depends on its interaction with other DNA-binding co-factors.Results: NAC1 interacts with BCL6 via its C-terminal BEN domain and forms a complex that binds the promoter region and activates transcription of the NAC1 target gene, FOXQ1. NAC1 and BCL6 were coordinately upregulated. Our analysis also identified a novel function of NAC1 in attenuating BCL6 auto-downregulation in ovarian cancer. Lastly, we found a significant overlap among NAC1- and BCL6-regulated genes in tumor cells, suggesting that NAC1 and BCL6 coordinately control transcription in cancer.Conclusions: The results of this study provide a novel mechanistic insight into the oncogenic roles of NAC1 and underline the importance of developing the NAC1/BCL6-targeted cancer therapy.Methods: Using the Cistrome database and Chromatin Immunoprecipitation (ChIP) analyses, we identified BCL6 as a potential NAC1- interacting molecule. Co-immunoprecipitation (Co-IP), luciferase reporter assay, immunohistochemistry and microarray analysis were performed to analyze the interaction between NAC1 and BCL6 and the mechanisms by which they regulate the downstream genes including FOXQ1.

NACC-1 regulates hepatocellular carcinoma cell malignancy and is targeted by miR-760

Hepatocellular carcinoma (HCC) is the most prominent form of presentation in liver cancer. It is also the fourth most common cause of cancer-associated deaths globally. The role of nucleus accumbens associated protein-1 (NACC-1) has been evaluated in several cancers. This protein is a transcriptional regulator that regulates a number of significant cellular processes. In the current study, we aimed to understand the role of NACC-1 in HCC. Primarily, we measured the expression of NACC-1 using quantitative real time polymerase chain reaction and western blot analysis. We knocked down the expression of NACC-1 in HCC cell lines Huh7 and HepG2 by transferring a commercially synthesized small interfering RNA and explored the impact of NACC-1 knockdown on cellular growth, migration, invasion, and chemoresistance to doxorubicin. Through bioinformatic analysis, we identified NACC-1 as a potential target of miR-760. Using a dual reporter luciferase assay, we confirmed the predicted target and assessed miR-760-mediated regulation of NACC-1 and rescue of tumorigenic phenotypes. We observed increased expression of NACC-1 in HCC. Furthermore, knockdown of NACC-1 resulted in reduced cell proliferation and invasion and increased susceptibility to doxorubicin-mediated chemosensitivity. Overexpression of miR-760 in HCC cell lines rescued NACC-1-mediated migration and invasion. We revealed that miR-760 regulated NACC-1 expression in HCC. Our data indicated that both miR-760 and NACC-1 could be used as prognostic markers, and miR-760 may have therapeutic benefits for HCC and other cancers.

Identification of a small-molecule compound that inhibits homodimerization of oncogenic NAC1 protein and sensitizes cancer cells to anticancer agents

Nucleus accumbens-associated protein-1 (NAC1) is a transcriptional repressor encoded by the NACC1 gene, which is amplified and overexpressed in various human cancers and plays critical roles in tumor development, progression, and drug resistance. NAC1 has therefore been explored as a potential therapeutic target for managing malignant tumors. However, effective approaches for effective targeting of this nuclear protein remain elusive. In this study, we identified a core unit consisting of Met7 and Leu90 in NAC1's N-terminal domain (amino acids 1-130), which is critical for its homodimerization and stability. Furthermore, using a combination of computational analysis of the NAC1 dimerization interface and high-throughput screening (HTS) for small molecules that inhibit NAC1 homodimerization, we identified a compound (NIC3) that selectively binds to the conserved Leu-90 of NAC1 and prevents its homodimerization, leading to proteasomal NAC1 degradation. Moreover, we demonstrate that NIC3-mediated down-regulation of NAC1 protein sensitizes drug-resistant tumor cells to conventional chemotherapy and enhances the antimetastatic effect of the antiangiogenic agent bevacizumab both in vitro and in vivo These results suggest that small-molecule inhibitors of NAC1 homodimerization may effectively sensitize cancer cells to some anticancer agents and that NAC1 homodimerization could be further explored as a potential therapeutic target in the development of antineoplastic agents.

NACC1, as a Target of MicroRNA-331-3p, Regulates Cell Proliferation in Urothelial Carcinoma Cells.

The nucleus accumbens-associated protein 1 (NACC1) is a transcription factor constitutively expressed in the urothelium, where it regulates cell growth, senescence, autophagy, and epithelial-mesenchymal transition. microRNA (miRNA) constitutes a class of small non-coding RNAs which are involved in cell proliferation, differentiation, and progression of tumors. miRNAs and their target molecules are utilized for molecular diagnosis of urothelial carcinoma. NACC1 is one of several putative target molecules of miR-331-3p, and is associated with cell proliferation in cancers such as prostate and cervical cancer. Functional experiments involving miR-331-3p and its target molecule NACC1 were conducted using the urothelial carcinoma (UC) cell lines, T24, UMUC6, and KU7. Furthermore, quantitative reverse transcription polymerase chain reaction and immunostaining were performed to evaluate the expression of NACC1 in UC derived from transurethral resection of bladder tumor (TUR-Bt) specimens. The methane thiosulfonate (MTS) assay revealed that cell proliferation was significantly reduced after transient transfection of miR-331-3p precursor and/or NACC1 siRNA in UC cells. Cell senescence via cell cycle arrest at the G1 phase was induced by NACC1 inhibition. On the other hand, suppression of NACC1 induced cell migration and invasion abilities. Immunohistochemical analysis of TUR-Bt specimens revealed that over 70% of UC cells presented strongly positive results for NACC1. In contrast, normal urothelial cells were weakly positive for NACC1. It was also found that NACC1 expression was lower in invasive UC cells than in non-invasive UC cells. Loss of NACC1 induced vessel invasion in invasive UC tissues. The present results indicate that NACC1 regulated by miR-331-3p contributes to cell proliferation, and is involved in cell migration and invasion. This suggests that NACC1 can serve as a potential target molecule for the prediction and prognosis of UC, and can contribute to effective treatment strategies.

NAC1 promotes the migration of prostate cancer cells and participates in osteoclastogenesis by negatively regulating IFNβ.

Nucleus accumbens-associated protein 1 (NAC1), a transcriptional co-regulator, is overexpressed in advanced prostate cancer. However, the NAC1-regulated transcriptome has not been completely explored. In the present study, the functional silencing of NAC1 blocked the migration of prostate cancer cells and suppress osteoclastogenesis. The present study also determined that NAC1 was overexpressed in the highly aggressive prostate cancer cell lines PC-3, DU-145 and LNCaP. NAC1 small interfering RNA treatment of DU-145 cells decreased cell migration, but interestingly had no significant effects on cell proliferation. Furthermore, microarray analysis showed that a group of genes may be associated with the development of prostate cancer after NAC1 knockdown, including interferon-β (IFNβ), which is reported to be involved in osteoclastogenesis, an important factor affecting bone metastasis. The mechanisms of NAC1 function were further explored by co-culture studies using PC-3 and RAW264.7 osteoclast precursor cells, which demonstrated that silencing NAC1 downregulated the genes associated with the activation of osteoclasts. Furthermore, it was revealed that NAC1 had the ability to affect the release of IFNβ into the extracellular environment. Together, these findings indicated that NAC1 promoted cell migration, and that NAC1 may have a key role in osteoclastogenesis.

NAC1 Regulates Somatic Cell Reprogramming by Controlling Zeb1 and E-cadherin Expression.

SummaryReprogramming somatic cells to induced pluripotent stem cells (iPSCs) is a long and inefficient process. A thorough understanding of the molecular mechanisms underlying reprogramming is paramount for efficient generation and safe application of iPSCs in medicine. While intensive efforts have been devoted to identifying reprogramming facilitators and barriers, a full repertoire of such factors, as well as their mechanistic actions, is poorly defined. Here, we report that NAC1, a pluripotency-associated factor and NANOG partner, is required for establishment of pluripotency during reprogramming. Mechanistically, NAC1 is essential for proper expression of E-cadherin by a dual regulatory mechanism: it facilitates NANOG binding to the E-cadherin promoter and fine-tunes its expression; most importantly, it downregulates the E-cadherin repressor ZEB1 directly via transcriptional repression and indirectly via post-transcriptional activation of the miR-200 miRNAs. Our study thus uncovers a previously unappreciated role for the pluripotency regulator NAC1 in promoting efficient somatic cell reprogramming.