IMPA2 promotes basal-like breast cancer aggressiveness by a MYC-mediated positive feedback loop.

Basal-like breast cancer (BLBC) is the most aggressive subtype with poor prognosis; however, the mechanisms underlying aggressiveness in BLBC remain poorly understood. In this study, we showed that in contrast to other subtypes, inositol monophosphatase 2 (IMPA2) was dramatically increased in BLBC. Mechanistically, IMPA2 expression was upregulated due to copy number amplification, hypomethylation of IMPA2 promoter and MYC-mediated transcriptional activation. IMPA2 promoted MI-PI cycle and IP3 production, and IP3 then elevated intracellular Ca2+ concentration, leading to efficient activation of NFAT1. In turn, NFAT1 up-regulated MYC expression, thereby fulfilling a positive feedback loop that enhanced aggressiveness of BLBC cells. Knockdown of IMPA2 expression caused the inhibition of tumorigenicity and metastasis of BLBC cells in vitro and in vivo. Clinically, high IMPA2 expression was strongly correlated with large tumor size, high grade, metastasis and poor survival, indicating poor prognosis in breast cancer patients. These findings suggest that IMPA2-mediated MI-PI cycle allows crosstalk between metabolic and oncogenic pathways to promote BLBC progression.

IL11 signaling mediates piR-2158 suppression of cell stemness and angiogenesis in breast cancer.

Emerging evidence has indicated the aberrant expression of PIWI-interacting RNAs (piRNAs) in human cancer cells to regulate tumor development and progression by governing cancer cell stemness. Herein, we identified downregulation of piR-2158 in human breast cancer tumors, especially in ALDH+ breast cancer stem cells (BCSCs) from patients and cell lines, which was further validated in two types of genetically engineered mouse models of breast cancer (MMTV-Wnt and MMTV-PyMT). Enforced overexpression of piR-2158 in basal-like or luminal subtypes of breast cancer cells suppressed cell proliferation, migration, epithelial-mesenchymal transition (EMT) and stemness in vitro. Administration of a dual mammary tumor-targeting piRNA delivery system in mice reduced tumor growth in vivo. RNA-seq, ChIP-seq and luciferase reporter assays demonstrated piR-2158 as a transcriptional repressor of IL11 by competing with AP-1 transcription factor subunit FOSL1 to bind the promoter of IL11. STAT3 signaling mediated piR-2158-IL11 regulation of cancer cell stemness and tumor growth. Moreover, by co-culturing of MDA-MB-231 and HUVECs in vitro and CD31 staining of tumor endothelial cells in vivo, we demonstrated inhibition of angiogenesis by piR-2158-IL11 in breast cancer. In conclusion, the current study not only reveals a novel mechanism through which piR-2158 inhibits mammary gland tumorigenesis via regulating cancer stem cells and tumor angiogenesis, but also provides a novel therapeutic strategy in treatment of breast cancer.

HIST1H1B Promotes Basal-Like Breast Cancer Progression by Modulating CSF2 Expression.

BACKGROUND: Basal-like breast cancer (BLBC) is associated with a poor clinical outcome; however, the mechanism of BLBC aggressiveness is still unclear. It has been shown that a linker histone functions as either a positive or negative regulator of gene expression in tumors. Here, we aimed to investigate the possible involvement and mechanism of HIST1H1B in BLBC progression. EXPERIMENTAL DESIGN: We analyzed multiple gene expression datasets to determine the relevance of HIST1H1B expression with BLBC. We employed quantitative real-time PCR, transwell assay, colony formation assay, and mammosphere assay to dissect the molecular events associated with the expression of HIST1H1B in human breast cancer. We studied the association of HIST1H1B with CSF2 by ChIP assay. Using tumorigenesis assays, we determine the effect of HIST1H1B expression on tumorigenicity of BLBC cells. RESULTS: Here, we show that the linker histone HIST1H1B is dramatically elevated in BLBC due to HIST1H1B copy number amplification and promoter hypomethylation. HIST1H1B upregulates colony-stimulating factor 2 (CSF2) expression by binding the CSF2 promoter. HIST1H1B expression promotes, whereas knockdown of HIST1H1B expression suppresses tumorigenicity. In breast cancer patients, HIST1H1B expression is positively correlated with large tumor size, high grade, metastasis and poor survival. CONCLUSION: HIST1H1B contributes to basal-like breast cancer progression by modulating CSF2 expression, indicating a potential prognostic marker and therapeutic target for this disease.

RNF20 Is Critical for Snail-Mediated E-Cadherin Repression in Human Breast Cancer.

BACKGROUND: E-cadherin, a hallmark of epithelial-mesenchymal transition (EMT), is often repressed due to Snail-mediated epigenetic modification; however, the exact mechanism remains unclear. There is an urgent need to understand the determinants of tumor aggressiveness and identify potential therapeutic targets in breast cancer. EXPERIMENTAL DESIGN: We studied the association of RNF20 with Snail and G9a by co-immunoprecipitation. We employed quantitative real-time PCR, ChIP, transwell assay, colony formation assay, and mammosphere assay to dissect the molecular events associated with the repression of E-cadherin in human breast cancer. We used a proteogenomic dataset that contains 105 breast tumor samples to determine the clinical relevance of RNF20 by Kaplan-Meier analyses. RESULTS: In this study, we identified that Snail interacted with RNF20, an E3 ubiquitin-protein ligase responsible for monoubiquitination of H2BK120, and G9a, a methyltransferase for H3K9me2. RNF20 expression led to the inhibition of E-cadherin expression in the human breast cancer cells. Mechanically, we showed that RNF20 and H3K9m2 were enriched on the promoter of E-cadherin and knockdown of Snail reduced the enrichment of RNF20, showing a Snail-dependent manner. RNF20 expression enhanced breast cancer cell migration, invasion, tumorsphere and colony formation. Clinically, patients with high RNF20 expression had shorter overall survival. CONCLUSION: RNF20 expression contributes to EMT induction and breast cancer progression through Snail-mediated epigenetic suppression of E-cadherin expression, suggesting the importance of RNF20 in breast cancer.

Nuclear translocation of PLSCR1 activates STAT1 signaling in basal-like breast cancer.

Rationale: Basal-like breast cancer (BLBC) is associated with high grade, distant metastasis, and poor prognosis; however, the mechanism underlying aggressiveness of BLBC is still unclear. Emerging evidence has suggested that phospholipid scramblase 1 (PLSCR1) is involved in tumor progression. Here, we aimed to study the possible involvement and molecular mechanisms of PLSCR1 contributing to the aggressive behavior of BLBC. Methods: The potential functions of PLSCR1 in breast cancer cells were assessed by Western blotting, colony formation, migration and invasion, Cell Counting Kit-8 assay, mammosphere formation and flow cytometry. The relationship between nuclear translocation of PLSCR1 and transactivation of STAT1 was examined by immunostaining, co-IP, ChIP, and quantitative reverse transcription PCR. The effect of PLSCR1 expression on BLBC cells was determined by in vitro and in vivo tumorigenesis and a lung metastasis mouse model. Results: Compared to other subtypes, PLSCR1 was considerably increased in BLBC. Phosphorylation of PLSCR1 at Tyr 69/74 contributed to the nuclear translocation of this protein. PLSCR1 was enriched in the promoter region of STAT1 and enhanced STAT3 binding to the STAT1 promoter, resulting in transactivation of STAT1; STAT1 then enhanced cancer stem cell (CSC)-like properties that promoted BLBC progression. The knockdown of PLSCR1 led to significant inhibitory effects on proliferation, migration, invasion, tumor growth and lung metastasis of BLBC cells. Clinically, high PLSCR1 expression was strongly correlated with large tumor size, high grade, metastasis, chemotherapy resistance, and poor survival, indicating poor prognosis in breast cancer patients. Conclusions: Our data show that overexpression and nuclear translocation of PLSCR1 provide tumorigenic and metastatic advantages by activating STAT1 signaling in BLBC. This study not only reveals a critical mechanism of how PLSCR1 contributes to BLBC progression, but also suggests potential prognostic indicators and therapeutic targets for this challenging disease.

Meta-analytic method reveal a significant association of theBDNF Val66Met variant with smoking persistence based on a large samples.

Although numerous genetic studies have reported the link between Val66Met in BDNF gene with smoking, the findings remain controversial, mainly due to small-to-moderate sample sizes. The main aim of current investigation is to explore whether the variant of Val66Met has any genetic functions in the progress of smoking persistence. The Val-based dominant genetic model considering Val/* (namely, Val/Val + Val/Met) and Met/Met as two genotypes with comparison of the frequency of each genotype in current smokers and never smokers. There were seven genetic association articles including eight independent datasets with 10,160 participants were chosen in current meta-analytic investigation. In light of the potent effects of ethnicity on homogeneity across studies, we carried out separated meta-analyses according to the ancestry origin by using the wide-used tool of Comprehensive Meta-analysis software (V 2.0). Our meta-analyses results indicated that the Val66Met polymorphism was significantly linked with smoking persistence based on either all the chosen samples (N = 10,160; Random and fixed models: pooled OR = 1.23; 95% CI = 1.03-1.46; P value = 0.012) or Asian samples (N = 2,095; Fixed model: pooled OR = 1.25; 95% CI = 1.01-1.54; P value = 0.044; Random model: pooled OR = 1.25; 95% CI = 1.001-1.56; P value = 0.049). No significant clue of bias in publications or heterogeneity across studies was detected. Thus, we conclude that the Val66Met (rs6265) variant conveys genetic susceptibility to maintaining smoking, and smokers who carry Val/* genotypes have a higher possibility of maintaining smoking than those having Met/Met genotype.

Loss of ABAT-Mediated GABAergic System Promotes Basal-Like Breast Cancer Progression by Activating Ca2+-NFAT1 Axis.

Basal-like breast cancer (BLBC) is the most aggressive subtype with a poor clinical outcome; however, the molecular mechanisms underlying aggressiveness in BLBC remain poorly understood. Methods: The effects of gamma-aminobutyrate aminotransferase (ABAT) on GABA receptors, Ca2+-NFAT1 axis, and cancer cell behavior were assessed by Ca2+ imaging, Western blotting, immunostaining, colony formation, and migration and invasion assays. We elucidated the relationship between ABAT and Snail by luciferase reporter and ChIP assays. The effect of ABAT expression on BLBC cells was determined by in vitro and in vivo tumorigenesis and a lung metastasis mouse model. Results: We showed that, compared to other subtypes, ABAT was considerably decreased in BLBC. Mechanistically, ABAT expression was downregulated due to Snail-mediated repression leading to increased GABA production. GABA then elevated intracellular Ca2+ concentration by activating GABA-A receptor (GABAA), which contributed to the efficient activation of NFAT1 in BLBC cells. ABAT expression resulted in inhibition of tumorigenicity, both in vitro and in vivo, and metastasis of BLBC cells. Thus, loss of ABAT contributed to BLBC aggressiveness by activating the Ca2+-NFAT1 axis. In breast cancer patients, loss of ABAT expression was strongly correlated with large tumor size, high grade and metastatic tendency, poor survival, and chemotherapy resistance. Conclusions: Our findings have provided underlying molecular details for the aggressive behavior of BLBC. The Snail-mediated downregulation of ABAT expression in BLBC provides tumorigenic and metastatic advantages by activating GABA-mediated Ca2+-NFAT1 axis. Thus, our results have identified potential prognostic indicators and therapeutic targets for this challenging disease.

ME1 promotes basal-like breast cancer progression and associates with poor prognosis.

Basal-like breast cancer (BLBC) is associated with a poor clinical outcome due to the few treatment options and absence of effective targeted agents. Here, we show that malic enzyme 1 (ME1) is dramatically upregulated in BLBC due to ME1 copy number amplification. ME1 expression increases glucose uptake and lactate production, and reduces oxygen consumption, leading to aerobic glycolysis. ME1 expression promotes, whereas knockdown of ME1 expression suppresses tumorigenicity. In breast cancer patients, ME1 expression is positively correlated with large tumor size, high grade, poor survival, and chemotherapy resistance. Our study not only contributes to a new understanding of how metabolic reprogramming contributes to BLBC progression, but also provides a potential prognostic marker and therapeutic target for this challenging disease.

Inhibition of UGT8 suppresses basal-like breast cancer progression by attenuating sulfatide-αVß5 axis.

Basal-like breast cancer (BLBC) is associated with a poor clinical outcome as a result of the few treatment options and poor therapeutic response. Here, we report that elevated expression of urine diphosphate-galactose ceramide galactosyltransferase (UGT8) specifically occurs in BLBC and predicts poor prognosis in breast cancer patients. UGT8 expression is transcriptionally up-regulated by Sox10, triggering the sulfatide biosynthetic pathway; increased sulfatide activates integrin αVß5-mediated signaling that contributes to BLBC progression. UGT8 expression promotes, whereas UGT8 knockdown suppresses tumorigenicity and metastasis. Importantly, we identify that zoledronic acid (ZA), a marketed drug for treating osteoporosis and bone metastasis, is a direct inhibitor of UGT8, which blocks the sulfatide biosynthetic pathway. Significantly, a clinically achievable dosage of ZA exhibits apparent inhibitory effect on migration, invasion, and lung metastasis of BLBC cells. Together, our study suggests that UGT8 is a potential prognostic indicator and druggable target of BLBC and that pharmacologic inhibition of UGT8 by ZA offers a promising opportunity for treating this challenging disease.

AKR1B1 promotes basal-like breast cancer progression by a positive feedback loop that activates the EMT program.

Basal-like breast cancer (BLBC) is associated with high-grade, distant metastasis and poor prognosis. Elucidating the determinants of aggressiveness in BLBC may facilitate the development of novel interventions for this challenging disease. In this study, we show that aldo-keto reductase 1 member B1 (AKR1B1) overexpression highly correlates with BLBC and predicts poor prognosis in breast cancer patients. Mechanistically, Twist2 transcriptionally induces AKR1B1 expression, leading to nuclear factor κB (NF-κB) activation. In turn, NF-κB up-regulates Twist2 expression, thereby fulfilling a positive feedback loop that activates the epithelial-mesenchymal transition program and enhances cancer stem cell (CSC)-like properties in BLBC. AKR1B1 expression promotes, whereas AKR1B1 knockdown inhibits, tumorigenicity and metastasis. Importantly, epalrestat, an AKR1B1 inhibitor that has been approved for the treatment of diabetic complications, significantly suppresses CSC properties, tumorigenicity, and metastasis of BLBC cells. Together, our study identifies AKR1B1 as a key modulator of tumor aggressiveness and suggests that pharmacologic inhibition of AKR1B1 has the potential to become a valuable therapeutic strategy for BLBC.