Up-regulation of Dsg2 confered stem cells with malignancy through wnt/ß-catenin signaling pathway.

In the previous study, we originally developed cancer stem cells (CSCs) models from mouse induced pluripotent stem cells (miPSCs) by culturing miPSCs in the conditioned medium of cancer cell lines, which mimiced as carcinoma microenvironment. However, the molecular mechanism of conversion in detail remains to be uncovered. Microarray analysis of the CSCs models in this study revealed Dsg2, one of the members of the desmosomal cadherin family, was up-regulated when compared with the original miPSCs. Moreover, the expression of key factors in Wnt/ß-catenin signaling pathway were also found up-regulated in one of the CSCs models, named miPS-LLCcm. An autocrine loop was implied between Dsg2 and Wnt/ß-catenin signaling pathway when miPSCs were treated with Wnt/ß-catenin signaling pathway activators, Wnt3a and CHIR99021, and when the CSCs model were treated with inhibitors, IWR-1 and IWP-2. Furthermore, the ability of proliferation and self-renewal in the CSCs model was markedly decreased in vitro and in vivo when Dsg2 gene was knocked down by shRNA. Our results showed that the Wnt/ß-catenin signaling pathway is activated by the up-regulation of Dsg2 expresssion during the conversion of miPSCs into CSCs implying a potential mechanism of the tranformation of stem cells into malignant phenotype.

Mechanisms of resistance to estrogen receptor modulators in ER+/HER2- advanced breast cancer.

Endocrine therapy represents a mainstay adjuvant treatment of estrogen receptor-positive (ER+) breast cancer in clinical practice with an overall survival (OS) benefit. However, the emergence of resistance is inevitable over time and is present in one-third of the ER+ breast tumors. Several mechanisms of endocrine resistance in ER+/HER2- advanced breast cancers, through ERα itself, receptor tyrosine signaling, or cell cycle pathway, have been identified to be pivotal in endocrine therapy. The epigenetic alterations also contribute to ensuring tumor cells' escape from endocrine therapies. The strategy of combined hormone therapy with targeted pharmaceutical compounds has shown an improvement of progression-free survival or OS in clinical practice, including three different classes of drugs: CDK4/6 inhibitors, selective inhibitor of PI3Kα and mTOR inhibitors. Many therapeutic targets of cell cycle pathway and cell signaling and their combination strategies have recently entered clinical trials. This review focuses on Cyclin D-CDK4/6-RB axis, PI3K pathway and HDACs. Additionally, genomic evolution is complex in tumors exposed to hormonal therapy. We highlight the genomic alterations present in ESR1 and PIK3CA genes to elucidate adaptive mechanisms of endocrine resistance, and discuss how these mutations may inform novel combinations to improve clinical outcomes in the future.

Transmembrane E3 ligase RNF183 mediates ER stress-induced apoptosis by degrading Bcl-xL.

The accumulation of misfolded proteins in the endoplasmic reticulum (ER) causes ER stress and triggers the unfolded protein response (UPR). Failure to resolve ER stress leads to apoptotic cell death via a yet unclear mechanism. Here, we show that RNF183, a membrane-spanning RING finger protein, localizes to the ER and exhibits classic E3 ligase activities. Sustained ER stress induced by different treatments increases RNF183 protein levels posttranscriptionally in an IRE1α-dependent manner. Activated IRE1 reduces the level of miR-7, which increases the stability of RNF183 transcripts. In addition, overexpression of RNF183 leads to increased apoptosis and its depletion alleviates ER stress-induced apoptosis. Furthermore, RNF183 interacts with Bcl-xL, an antiapoptotic member of the Bcl-2 family, and polyubiquitinates Bcl-xL for degradation. Thus, RNF183 plays an important role in executing programmed cell death upon prolonged ER stress, likely by inducing apoptosis through Bcl-xL.

Genetic analysis and preliminary function study of miR-423 in breast cancer.

Common genetic variants (single nucleotide polymorphisms SNPs) in microRNA (miRNA) genes may alter their maturation or expression and play a role in the formation of human cancer. Recently, the association between the SNP rs6505162 in pre-miR-423 and cancer risk has been frequently evaluated in diverse populations and in a range of cancers. In this study, we determined the genotypes of SNP rs6505162 in 5 matched cell lines (breast cancer cell lines and their corresponding peripheral blood cell lines) and 114 matched clinical specimens (clinical breast carcinoma specimens and their corresponding normal tissues), compared the processing efficiency of pri-miRNA to mature forms between pre-miR-423-12C (wild-type) and pre-miR-423-12A (mutant-type) expression vectors, and evaluated the function of miR-423 on cell proliferation. Our data showed that two out of five breast cancer cell lines and 8.77 % (10/114) of tumors underwent somatic mutations of the rs6505162 SNP, and somatic mutation state was significantly correlated with the expression of clinicopathologic variables, proliferating cell nuclear antigen (PCNA) and mutant p53. The pre-miR-423-12C SNP blocked the endogenous processing of pri-miR-423 to its two mature miRNAs. Interestingly, selected pre-miR-423-12C stable cell population had lower proliferation ability than pre-miR-423-12A stable cell population. Moreover, miR-423 promoted cell proliferation in breast cancer cell lines through its miR-423-3p strand, not miR-423-5p. Taken together, these results suggest that the SNP rs6505162 in pre-miR-423 affects the mature miR expression, and miR-423 plays a potentially oncogenic role in breast tumorigenesis.

Critical role of dendritic cell-derived IL-27 in antitumor immunity through regulating the recruitment and activation of NK and NKT cells.

Critical roles of IL-27 in autoimmune diseases and infections have been reported; however, the contribution of endogenous IL-27 to tumor progression remains elusive. In this study, by using IL-27p28 conditional knockout mice, we demonstrate that IL-27 is critical in protective immune response against methyl-cholanthrene-induced fibrosarcoma and transplanted B16 melanoma, and dendritic cells (DCs) are the primary source. DC-derived IL-27 is required for shaping tumor microenvironment by inducing CXCL-10 expression in myeloid-derived suppressor cells and regulating IL-12 production from DCs, which lead to the recruitment and activation of NK and NKT cells resulting in immunological control of tumors. Indeed, reconstitution of IL-27 or CXCL-10 in tumor site significantly inhibits tumor growth and restores the number and activation of NK and NKT cells. In summary, our study identifies a previous unknown critical role of DC-derived IL-27 in NK and NKT cell-dependent antitumor immunity through shaping tumor microenvironment, and sheds light on developing novel therapeutic approaches based on IL-27.

[Structure and biological functions of mammalian LEM-domain proteins].

During the process of open mitosis in higher eukaryotic cells, the nuclear envelope (NE) is disassembled and reassembled with highly organized and periodical dynamic morphological changes. Recent studies demonstrated that LEM-domain protein family mediates interactions among inner nuclear membrane, nuclear lamina protein and chromatin by interacting with barrier-to-autointegration-factor (BAF). The structure and function of the ternary complex formed by LEM-domain protein, nuclear lamina protein and BAF are dependent on each other. Moreover, the network formation based on this structure and function is critical for the development of basic biological processes of nuclear, and it plays important roles in chromatin separation in late metaphase and anaphase, NE reassembly after mitosis, morphological maintenance of nuclear and NE in interphase, regulation of DNA replication and DNA damage repair, regulation of gene expression and signaling pathway, and infection of retrovirus. Mutations in genes encoding LEM family proteins have important impacts on development and progression of laminopathic diseases and tumorigenesis. This review provides a detailed summary of structural and functional studies of the LEM family proteins.

ROOT HAIR DEFECTIVE3 family of dynamin-like GTPases mediates homotypic endoplasmic reticulum fusion and is essential for Arabidopsis development.

In all eukaryotic cells, the endoplasmic reticulum (ER) forms a tubular network whose generation requires the fusion of ER membranes. In Arabidopsis (Arabidopsis thaliana), the membrane-bound GTPase ROOT HAIR DEFECTIVE3 (RHD3) is a potential candidate to mediate ER fusion. In addition, Arabidopsis has two tissue-specific isoforms of RHD3, namely RHD3-like (RL) proteins, and their function is not clear. Here, we show that a null allele of RHD3, rhd3-8, causes growth defects and shortened root hairs. A point mutant, rhd3-1, exhibits a more severe growth phenotype than the null mutant, likely because it exerts a dominant-negative effect on the RL proteins. Genetic analysis reveals that the double deletion of RHD3 and RL1 is lethal and that the rhd3 rl2 plants produce no viable pollen, suggesting that the RL proteins are redundant to RHD3. RHD3 family proteins can replace Sey1p, the homolog of RHD3 in yeast (Saccharomyces cerevisiae), in the maintenance of ER morphology, and they are able to fuse membranes both in vivo and in vitro. Our results suggest that RHD3 proteins mediate ER fusion and are essential for plant development and that the formation of the tubular ER network is of general physiological significance.

Upregulation of ATBF1 by progesterone-PR signaling and its functional implication in mammary epithelial cells.

Progesterone (Pg) is an essential steroid hormone during mammary gland development and tumorigenesis, including the maintenance of epithelial stem/progenitor cells. Pg functions through interaction with the progesterone receptors (PR) and Pg-PR signaling is thought to be mediated by key transcription factors, which are largely unidentified. In this study, we have identified the ATBF1 transcription factor as a transcriptional target of Pg-PR signaling in mammary epithelial cells. Pg treatment dramatically increased ATBF1 expression at both mRNA and protein levels in cultured cells and mammary tissues. As expected, the induction of ATBF1 was PR-dependent, as it only occurred in PR-positive but not in PR-negative cells, and pretreatment with the Pg antagonist RU-486 or RNAi-mediated knockdown of PR abolished the upregulation of ATBF1 by Pg. Promoter-reporter and ChIP assays further showed that Pg-activated PR directly binds to the ATBF1 promoter to induce its transcription. Prevention of ATBF1 induction inhibited the function of Pg in promoting progenitor cell transition, as indicated by colony formation in a Matrigel culture assay and expression of stem cell markers CD49f and CD44. These findings suggest that ATBF1 plays a crucial role in the Pg-PR signaling pathway in mammary epithelial cells.

Role of ERRF, a novel ER-related nuclear factor, in the growth control of ER-positive human breast cancer cells.

Whereas estrogen-estrogen receptor α (ER) signaling plays an important role in breast cancer growth, it is also necessary for the differentiation of normal breast epithelial cells. How this functional conversion occurs, however, remains unknown. Based on a genome-wide sequencing study that identified mutations in several breast cancer genes, we examined some of the genes for mutations, expression levels, and functional effects on cell proliferation and tumorigenesis. We present the data for C1orf64 or ER-related factor (ERRF) from 31 cell lines and 367 primary breast cancer tumors. Whereas mutation of ERRF was infrequent (1 of 79 or 1.3%), its expression was up-regulated in breast cancer, and the up-regulation was more common in lower-stage tumors. In addition, increased ERRF expression was significantly associated with ER and/or progesterone receptor (PR) positivity, which was still valid in human epidermal growth factor receptor 2 (HER2)-negative tumors. In ER-positive tumors, ERRF expression was inversely correlated with HER2 status. Furthermore, higher ERRF protein expression was significantly associated with better disease-free survival and overall survival, particularly in ER- and/or PR-positive and HER2-negative tumors (luminal A subtype). Functionally, knockdown of ERRF in two ER-positive breast cancer cell lines, T-47D and MDA-MB-361, suppressed cell growth in vitro and tumorigenesis in xenograft models. These results suggest that ERRF plays a role in estrogen-ER-mediated growth of breast cancer cells and could, thus, be a potential therapeutic target.

Reprogramming of ovarian aging epigenome by resveratrol.

Resveratrol is an antiaging, antioxidant, and anti-inflammatory natural polyphenolic compound. Growing evidence indicates that resveratrol has potential therapeutic effects for improving aging ovarian function. However, the mechanisms underlying prolonged reproductive longevity remain elusive. We found that resveratrol ameliorates ovarian aging transcriptome, some of which are associated with specific changes in methylome. In addition to known aging transcriptome of oocytes and granulosa cells such as decline in oxidoreductase activity, metabolism and mitochondria function, and elevated DNA damage and apoptosis, actin cytoskeleton are notably downregulated with age, and these defects are mostly rescued by resveratrol. Moreover, the aging-associated hypermethylation of actin cytoskeleton is decreased by resveratrol. In contrast, deletion of Tet2, involved in DNA demethylation, abrogates resveratrol-reprogrammed ovarian aging transcriptome. Consistently, Tet2 deficiency results in additional altered pathways as shown by increased mTOR and Wnt signaling, as well as reduced DNA repair and actin cytoskeleton with mouse age. Moreover, genes associated with oxidoreductase activity and oxidation-reduction process were hypermethylated in Tet2-deficient oocytes from middle-age mice treated with resveratrol, indicating that loss of Tet2 abolishes the antioxidant effect of resveratrol. Taking together, our finding provides a comprehensive landscape of transcriptome and epigenetic changes associated with ovarian aging that can be reprogrammed by resveratrol administration, and suggests that aberrantly increased DNA methylation by Tet2 deficiency promotes additional aging epigenome that cannot be effectively restored to younger state by resveratrol.

Culture conditions of mouse ESCs impact the tumor appearance in vivo.

Various culture conditions by small molecules have been explored to extend pluripotency of stem cells, but their impacts on cell fate in vivo remain elusive. We systematically compared the effects of various culture conditions on the pluripotency and cell fate in vivo of mouse embryonic stem cells (ESCs) by tetraploid embryo complementation assay. Conventional ESC cultures in serum/LIF-based condition produced complete ESC mice and also the survival to adulthood at the highest rates of all other chemical-based cultures. Moreover, long-term examination of the survived ESC mice demonstrated that conventional ESC cultures did not lead to visible abnormality for up to 1.5-2 years, whereas the prolonged chemical-based cultures developed retroperitoneal atypical teratomas or leiomyomas. The chemical-based cultures exhibited transcriptomes and epigenomes that typically differed from those of conventional ESC cultures. Our results warrant further refinement of culture conditions in promoting the pluripotency and safety of ESCs in future applications.

Chromodomain helicase DNA binding protein 5 plays a tumor suppressor role in human breast cancer.

INTRODUCTION: The chromodomain helicase DNA binding protein 5 (CHD5) has recently been identified as a tumor suppressor in a mouse model. The CHD5 locus at 1p36 is deleted, and its mutation has been detected in breast cancer. We, therefore, evaluated whether CHD5 plays a role in human breast cancer. METHODS: We screened mutations in 55 tumors, determined promoter methylation in 39 tumors, measured RNA expression in 90 tumors, analyzed protein expression in 289 tumors, and correlated expression changes with clinicopathological characteristics of breast cancer. Functional effects of CHD5 on cell proliferation, invasion and tumorigenesis were also tested. RESULTS: Although only one mutation was detected, CHD5 mRNA expression was significantly reduced, accompanied by frequent genomic deletion and promoter methylation, in breast cancer. The extent of methylation was significantly associated with reduced mRNA expression, and demethylating treatment restored CHD5 expression. Lower CHD5 mRNA levels correlated with lymph node metastasis (P = 0.026). CHD5 protein expression was also reduced in breast cancer, and lack of CHD5 expression significantly correlated with higher tumor stage, ER/PR-negativity, HER2 positivity, distant metastasis and worse patient survival (P ≤ 0.01). Functionally, ectopic expression of CHD5 in breast cancer cells inhibited cell proliferation and invasion in vitro and tumorigenesis in nude mice. Consistent with the inhibition of invasion, CHD5 down-regulated mesenchymal markers vimentin, N-cadherin and ZEB1 in breast cancer cells. CONCLUSION: Down-regulation of CHD5, mediated at least in part by promoter methylation, contributes to the development and progression of human breast cancer.

Ovarian aging: mechanisms and intervention strategies.

Ovarian reserve is essential for fertility and influences healthy aging in women. Advanced maternal age correlates with the progressive loss of both the quantity and quality of oocytes. The molecular mechanisms and various contributing factors underlying ovarian aging have been uncovered. In this review, we highlight some of critical factors that impact oocyte quantity and quality during aging. Germ cell and follicle reserve at birth determines reproductive lifespan and timing the menopause in female mammals. Accelerated diminishing ovarian reserve leads to premature ovarian aging or insufficiency. Poor oocyte quality with increasing age could result from chromosomal cohesion deterioration and misaligned chromosomes, telomere shortening, DNA damage and associated genetic mutations, oxidative stress, mitochondrial dysfunction and epigenetic alteration. We also discuss the intervention strategies to delay ovarian aging. Both the efficacy of senotherapies by antioxidants against reproductive aging and mitochondrial therapy are discussed. Functional oocytes and ovarioids could be rejuvenated from pluripotent stem cells or somatic cells. We propose directions for future interventions. As couples increasingly begin delaying parenthood in life worldwide, understanding the molecular mechanisms during female reproductive aging and potential intervention strategies could benefit women in making earlier choices about their reproductive health.

The efficacy of PI3Kγ and EGFR inhibitors on the suppression of the characteristics of cancer stem cells.

Cancer stem cells (CSCs) are capable of continuous proliferation, self-renewal and are proposed to play significant roles in oncogenesis, tumor growth, metastasis and cancer recurrence. We have established a model of CSCs that was originally developed from mouse induced pluripotent stem cells (miPSCs) by proposing miPSCs to the conditioned medium (CM) of cancer derived cells, which is a mimic of carcinoma microenvironment. Further research found that not only PI3K-Akt but also EGFR signaling pathway was activated during converting miPSCs into CSCs. In this study, we tried to observe both of PI3Kγ inhibitor Eganelisib and EGFR inhibitor Gefitinib antitumor effects on the models of CSCs derived from miPSCs (miPS-CSC) in vitro and in vivo. As the results, targeting these two pathways exhibited significant inhibition of cell proliferation, self-renewal, migration and invasion abilities in vitro. Both Eganelisib and Gefitinib showed antitumor effects in vivo while Eganelisib displayed more significant therapeutic efficacy and less side effects than Gefitinib on all miPS-CSC models. Thus, these data suggest that the inhibitiors of PI3K and EGFR, especially PI3Kγ, might be a promising therapeutic strategy against CSCs defeating cancer in the near future.

Oncogenic function of microtubule end-binding protein 1 in breast cancer.

Microtubule end-binding protein 1 (EB1) is an evolutionarily conserved protein that regulates microtubule dynamics and participates in diverse cell activities. Here, we demonstrate that EB1 expression is up-regulated in human breast cancer specimens and cell lines. The level of EB1 correlates with clinicopathological parameters indicating the malignancy of breast cancer, including higher histological grade, higher pathological tumour node metastasis (pTNM) stage, and higher incidence of lymph node metastasis. Knockdown of EB1 expression remarkably inhibits cancer cell proliferation, and conversely, elevation of its expression promotes cell proliferation. Our data further show that EB1 promotes colony formation and enhances tumour growth in nude mice. In addition, EB1 stimulates Aurora-B activity in breast cancer cells, and EB1 expression correlates with increased Aurora-B activity in clinical samples of breast cancer. These findings thus suggest an oncogenic role for EB1 in breast cancer.

Down-regulation of tumor suppressor gene FEZ1/LZTS1 in breast carcinoma involves promoter methylation and associates with metastasis.

FEZ1/LZTS1 is a tumor suppressor gene located in chromosomal band 8p22, and methylation has been identified as a mechanism for its loss of function in tumors. Chromosomal deletion at 8p22 is also frequent in breast cancer. We therefore examined whether LZTS1 plays a role in breast cancer. We analyzed expression of LZTS1 at both the RNA and protein levels, and promoter methylation in a number of primary tumors and cell lines from breast cancer. We also examined the association between LZTS1 expression and different clinicopathological parameters of breast cancer. We found that the expression of LZTS1 mRNA was reduced in 25 of 50 (50%) primary tumors and 29 of 30 (97%) breast cancer cell lines. Immunohistochemical staining showed that LZTS1 protein was absent or down-regulated in 72 (72%) of 100 primary breast carcinomas. Reduced expression of LZTS1 at either the RNA or protein level was significantly correlated with lymph node metastases (P < 0.05). DNA methylation analysis revealed that the LZTS1 gene was frequently methylated in both cell lines and primary tumors from breast cancer, and the extent of DNA methylation was correlated with reduced expression of the gene. These findings suggest that LZTS1 plays a role in the development and progression of breast cancer at least through promoter methylation-mediated transcriptional downregulation.

Zfhx3 is essential for progesterone/progesterone receptor signaling to drive ductal side-branching and alveologenesis in mouse mammary glands.

Progesterone (Pg)/progesterone receptor (PR) signaling drives mammary gland side-branching and alveologenesis, but the mechanisms through which Pg/PR signaling functions remain to be clarified. Using in vitro and in vivo models and histological and molecular analyses, we determined the role of Zfhx3 transcription factor in mammary gland development driven by Pg/PR signaling. Postnatal deletion of Zfhx3 in mouse mammary epithelial cells attenuated side-branching morphogenesis and alveologenesis. These effects were undetectable in the absence of Pg/PR signaling. During the estrus cycle, Zfhx3 expression corresponded to that of Pg, being at the highest level at the diestrus stage; Zfhx3 deletion inhibited mammary gland branching more potently at diestrus than estrus stage. Loss of Zfhx3 not only attenuated the expansion of stem/progenitor cells driven by Pg/PR signaling, but also impaired the function of Pg/PR signaling in the transcriptional activation of multiple genes. In addition, Pg/PR signaling significantly expanded PR- and Zfhx3-positive epithelial cells, and induced the physical association of ZFHX3 with PR. These findings establish Zfhx3 as an integral transcription factor of Pg/PR signaling in driving side-branching and alveologenesis during mammary gland development.

Telomere Maintenance-Associated PML Is a Potential Specific Therapeutic Target of Human Colorectal Cancer.

Telomere length maintenance is essential for cell proliferation, which is particularly prominent in cancer. We validate that the primary colorectal tumors exhibit heterogeneous telomere lengths but mostly (90%) short telomeres relative to normal tissues. Intriguingly, relatively short telomeres are associated with tumor malignancy as indicated by poorly differentiated state, and these tumors contain more cancer stem-like cells (CSLCs) identified by several commonly used markers CD44, EPHB2 or LGR5. Moreover, promyelocytic leukemia (PML) and ALT-associated PML nuclear bodies (APBs) are frequently found in tumors with short telomeres and high proliferation. In contrast, distant normal tissues rarely or only minimally express PML. Inhibition of PML and APBs by an ATR inhibitor decreases proliferation of CSLCs and organoids, suggesting a potential therapeutic target to progressive colorectal tumors. Together, telomere maintenance underling tumor progression is connected with CSLCs.

Characterization, expression profiles, intracellular distribution and association analysis of porcine PNAS-4 gene with production traits.

BACKGROUND: In a previous screen to identify differentially expressed genes associated with embryonic development, the porcine PNAS-4 gene had been found. Considering differentially expressed genes in early stages of muscle development are potential candidate genes to improve meat quality and production efficiency, we determined how porcine PNAS-4 gene regulates meat production. Therefore, this gene has been sequenced, expression analyzed and associated with meat production traits. RESULTS: We cloned the full-length cDNA of porcine PNAS-4 gene encoding a protein of 194 amino acids which was expressed in the Golgi complex. This gene was mapped to chromosome 10, q11-16, in a region of conserved synteny with human chromosome 1 where the human homologous gene was localized. Real-time PCR revealed that PNAS-4 mRNA was widely expressed with highest expression levels in skeletal muscle followed by lymph, liver and other tissues, and showed a down-regulated expression pattern during prenatal development while a up-regulated expression pattern after weaning. Association analysis revealed that allele C of SNP A1813C was prevalent in Chinese indigenous breeds whereas A was dominant allele in Landrace and Large White, and the pigs with homozygous CC had a higher fat content than those of the pigs with other genotypes (P < 0.05). CONCLUSION: Porcine PNAS-4 protein tagged with green fluorescent protein accumulated in the Golgi complex, and its mRNA showed a widespread expression across many tissues and organs in pigs. It may be an important factor affecting the meat production efficiency, because its down-regulated expression pattern during early embryogenesis suggests involvement in increase of muscle fiber number. In addition, the SNP A1813C associated with fat traits might be a genetic marker for molecular-assisted selection in animal breeding.

ZNF121 interacts with ZBRK1 and BRCA1 to regulate their target genes in mammary epithelial cells.

The novel zinc finger protein 121 (ZNF121) has been demonstrated to physically and functionally associate with the MYC oncoprotein to regulate cell proliferation and likely breast cancer development. To further understand how ZNF121 functions in cell proliferation and carcinogenesis, we identified and characterized the interaction of ZNF121 with zinc finger and BRCA1-interacting protein with a KRAB domain 1 (ZBRK1), a breast and ovarian cancer susceptibility protein 1 (BRCA1)-interacting protein, using the yeast two-hybrid assay and other approaches. We also found that ZNF121 bound to BRCA1. Functionally, ZFN121 suppressed the expression of ANG1 and HMGA2, two common downstream targets of ZBRK1 and BRCA1. Interestingly, ZNF121 also regulated the expression of BRCA1 and ZBRK1. These findings suggest that ZNF121 is likely a member of the BRCA1/CtIP/ZBRK1 repressor complex that plays a role in breast cancer.