Mitochondrial mutations and mitoepigenetics: Focus on regulation of oxidative stress-induced responses in breast cancers.

Epigenetic regulation of mitochondrial DNA (mtDNA) is an emerging and fast-developing field of research. Compared to regulation of nucler DNA, mechanisms of mtDNA epigenetic regulation (mitoepigenetics) remain less investigated. However, mitochondrial signaling directs various vital intracellular processes including aerobic respiration, apoptosis, cell proliferation and survival, nucleic acid synthesis, and oxidative stress. The later process and associated mismanagement of reactive oxygen species (ROS) cascade were associated with cancer progression. It has been demonstrated that cancer cells contain ROS/oxidative stress-mediated defects in mtDNA repair system and mitochondrial nucleoid protection. Furthermore, mtDNA is vulnerable to damage caused by somatic mutations, resulting in the dysfunction of the mitochondrial respiratory chain and energy production, which fosters further generation of ROS and promotes oncogenicity. Mitochondrial proteins are encoded by the collective mitochondrial genome that comprises both nuclear and mitochondrial genomes coupled by crosstalk. Recent reports determined the defects in the collective mitochondrial genome that are conducive to breast cancer initiation and progression. Mutational damage to mtDNA, as well as its overproliferation and deletions, were reported to alter the nuclear epigenetic landscape. Unbalanced mitoepigenetics and adverse regulation of oxidative phosphorylation (OXPHOS) can efficiently facilitate cancer cell survival. Accordingly, several mitochondria-targeting therapeutic agents (biguanides, OXPHOS inhibitors, vitamin-E analogues, and antibiotic bedaquiline) were suggested for future clinical trials in breast cancer patients. However, crosstalk mechanisms between altered mitoepigenetics and cancer-associated mtDNA mutations remain largely unclear. Hence, mtDNA mutations and epigenetic modifications could be considered as potential molecular markers for early diagnosis and targeted therapy of breast cancer. This review discusses the role of mitoepigenetic regulation in cancer cells and potential employment of mtDNA modifications as novel anti-cancer targets.

Neoadjuvant pyrotinib plus trastuzumab and chemotherapy for HER2-positive breast cancer: a prospective cohort study.

BACKGROUND: This prospective study aims to investigate the efficacy and safety of pyrotinib (P) combined with 4 cycles of epirubicin and cyclophosphamide followed by 4 cycles of taxane and trastuzumab (P + EC-TH) regimen as neoadjuvant therapy for human epidermal growth factor receptor 2 (HER2) positive breast cancer and to investigate the predictive value of p53, p63, and epidermal growth factor receptor (EGFR) status for neoadjuvant efficacy. METHODS: A total of 138 HER2-positive breast cancer patients who received neoadjuvant therapy and underwent surgery were included. Case group: 55 patients received P + EC-TH regimen. CONTROL GROUP: 83 patients received EC-TH regimen. The chi-square test, Fisher's exact test, and logistic regression analysis were applied. The primary endpoint was total pathologic complete response (tpCR), and the secondary endpoints were breast pathologic complete response (bpCR), overall response rate (ORR), and adverse events (AEs). RESULTS: In the case group, the tpCR rate was 63.64% (35/55), the bpCR rate was 69.09% (38/55), and the ORR was 100.00% (55/55). In the control group, the tpCR rate was 39.76% (33/83), the bpCR rate was 44.58% (37/83), and the ORR was 95.18% (79/83). The case group had significantly higher tpCR and bpCR rates than those of the control group (P < 0.05), but there was no significant difference in ORR (P > 0.05). The tpCR was associated with the status of estrogen receptor (ER), progesterone receptor (PR), and androgen receptor (AR), and the patients with any negative ER, PR, AR, or combined, were more likely to achieve tpCR than those with positive results (P < 0.05). The p53-positive patients were more likely to achieve tpCR and bpCR than p53-negative patients (P < 0.05). The incidence of hypokalemia and diarrhea in the case group was higher than that in the control group (P < 0.05). The AEs developed were all manageable, and no treatment-related death occurred. CONCLUSION: The efficacy and safety of the P + EC-TH regimen were verified by this study. The HER2-positive breast cancer patients treated with the EC-TH neoadjuvant regimen were more likely to achieve tpCR or bpCR if pyrotinib was administered simultaneously.

Circular RNA circ_IRAK3 contributes to tumor growth through upregulating KIF2A via adsorbing miR-603 in breast cancer.

BACKGROUND: Breast cancer (BC) threatens the health of women around the world. Researchers have proved that hsa_circ_0005505 (circ_IRAK3) facilitates BC cell invasion and migration, but the regulatory mechanisms of circ_IRAK3 in BC remain mostly unknown. We aim to explore a new mechanism by which circ_IRAK3 promotes BC progression. METHODS: Levels of circ_IRAK3, microRNA (miR)-603, and kinesin family member 2A (KIF2A) mRNA in BC tissues and cells were examined by quantitative real-time polymerase chain reaction (qRT-PCR). The cell cycle progression, colony formation, and proliferation of BC cells were evaluated by flow cytometry, plate clone, or 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) assays. The migration, invasion, and apoptosis of BC cells were determined by transwell or flow cytometry assays. Several protein levels were detected using western blotting. The targeting relationship between circ_IRAK3 or KIF2A and miR-603 was verified via dual-luciferase reporter assay. The role of circ_IRAK3 in vivo was verified by xenograft assay. RESULTS: We observed higher levels of circ_IRAK3 in BC tissues and cell lines than their respective controls. Functional experiments presented that circ_IRAK3 silencing induced BC cell apoptosis, curbed cell proliferation, migration, and invasion in vitro, and decreased tumor growth in vivo. Mechanistically, circ_IRAK3 could modulate kinesin family member 2A (KIF2A) expression through acting as a microRNA (miR)-603 sponge. miR-603 silencing impaired the effects of circ_IRAK3 inhibition on the malignant behaviors of BC cells. Also, the repressive effects of miR-603 mimic on the malignant behaviors of BC cells were weakened by KIF2A overexpression. CONCLUSIONS: circ_IRAK3 exerted a promoting effect on BC progression by modulating the miR-603/KIF2A axis, providing a piece of novel evidence for circ_IRAK3 as a therapeutic target for BC.

Retrospective analysis: 5509 cases of "totally implantable venous access port systems implantation (TIVAPS) depth" assisted by digital radiography.

PURPOSE: Modern oncological treatment in breast cancer patients requires the precise delivery of chemotherapy infusion into the central venous systems without toxicity. TIVAPS is the significant method of chemotherapy delivery although certain internal or external complications associated with their placement. However, the long-term use of TIVAPS is still a concern to minimize the complications such as venous thrombosis syndrome (VTS) and cardiac defects. The aim of this study is to investigate the potential disadvantages that may be avoided by digital radiography (DR)-assisted measurement of catheter depth pertinent to TIVAPS implanted system. METHODS: Retrospective analysis related to 5509 TIVAPS recipients of 99% female breast cancer patients and 1% male blood disorder patients registered from April 2013 to November 2017 were included in the study. Patients with TIVAPS catheter tip depth into superior vena cava into upper (group A), middle (group B), and lower (group C) parts were stratified for evaluation during implantation; DR-assisted measurement of TIVAPS was performed to decipher "tip depth of catheter" and determined the relevance of tip depth to complications such as VTS and cardiac defects. RESULTS: Incidence of VTS complications were significantly higher in TIVAPS recipients of group A (82.7%) than group B (16%) and group C (0.12%) in which the "tip depth of TIVAPS was deeper" (P < 0.01). Defects in heart function are higher in group C (59.6%) than group A (15.8%) and group B (24.6%) in which the "tip depth of TIVAPS was deeper" (P < 0.01). CONCLUSION: DR-assisted measurement can more accurately determine the depth of TIVAPS catheter implantation, and avoid the incidence of related complications, and provide a better method for surgeons.

Pyrotinib plus capecitabine versus lapatinib plus capecitabine for the treatment of HER2-positive metastatic breast cancer (PHOEBE): a multicentre, open-label, randomised, controlled, phase 3 trial.

BACKGROUND: Despite therapeutic advances in HER2-positive metastatic breast cancer, resistance to trastuzumab inevitably develops. In the PHOEBE study, we aimed to assess the efficacy and safety of pyrotinib (an irreversible pan-HER inhibitor) plus capecitabine after previous trastuzumab. METHODS: This is an open-label, randomised, controlled, phase 3 trial done at 29 hospitals in China. Patients with pathologically confirmed HER2-positive metastatic breast cancer, aged 18-70 years, who had an Eastern Cooperative Oncology Group performance status of 0 or 1, and had been previously treated with trastuzumab and taxanes were randomly assigned (1:1) to receive oral pyrotinib 400 mg or lapatinib 1250 mg once daily plus oral capecitabine 1000 mg/m2 twice daily on days 1-14 of each 21-day cycle. Randomisation was done via a centralised interactive web-response system with a block size of four or six and stratified by hormone receptor status and previous lines of chemotherapy for metastatic disease. The primary endpoint was progression-free survival according to masked independent central review. Efficacy and safety were assessed in all patients who received at least one dose of the study drugs. Results presented here are from a prespecified interim analysis. This study is registered with ClinicalTrials.gov, NCT03080805. FINDINGS: Between July 31, 2017, and Oct 30, 2018, 267 patients were enrolled and randomly assigned. 134 patients received pyrotinib plus capecitabine and 132 received lapatinib plus capecitabine. At data cutoff of the interim analysis on March 31, 2019, median progression-free survival was significantly longer with pyrotinib plus capecitabine (12·5 months [95% CI 9·7-not reached]) than with lapatinib plus capecitabine (6·8 months [5·4-8·1]; hazard ratio 0·39 [95% CI 0·27-0·56]; one-sided p<0·0001). The most common grade 3 or worse adverse events were diarrhoea (41 [31%] in the pyrotinib group vs 11 [8%] in the lapatinib group) and hand-foot syndrome (22 [16%] vs 20 [15%]). Serious adverse events were reported for 14 (10%) patients in the pyrotinib group and 11 (8%) patients in the lapatinib group. No treatment-related deaths were reported in the pyrotinib group and one sudden death in the lapatinib group was considered treatment related. INTERPRETATION: Pyrotinib plus capecitabine significantly improved progression-free survival compared with that for lapatinib plus capecitabine, with manageable toxicity, and can be considered an alternative treatment option for patients with HER2-positive metastatic breast cancer after trastuzumab and chemotherapy. FUNDING: Jiangsu Hengrui Medicine and National Key R&D Program of China. TRANSLATIONS: For the Chinese translation of the abstract see Supplementary Materials section.

CircNOL10 suppresses breast cancer progression by sponging miR-767-5p to regulate SOCS2/JAK/STAT signaling.

BACKGROUND: Circular RNAs (circRNAs) have caught increasing attentions and interests for their important involvement in cancer initiation and progression. This study aims to investigate the biological functions of circNOL10 and its potential molecular mechanisms in breast cancer (BC). MATERIALS AND METHODS: qRT-PCR and western blot assays were performed to measure the expression of related genes. CCK-8, colony formation, flow cytomerty and transwell assays were used to assess cell proliferation, cell cycle, migration and invasion. RNA pull-down, luciferase reporter and RIP assays were applied to address the potential regulatory mechanism of circNOL10. RESULTS: CircNOL10 was down-regulated in BC tissues and cells. Low expression of circNOL10 was associated with larger tumor size, advanced TNM stage, lymph node metastasis and unfavorable prognosis. Overexpression of circNOL10 inhibited cell proliferation, migration, invasion and EMT in vitro and slowed xenograft tumor growth in vivo. Mechanistically, circNOL10 could act as a molecular sponge for miR-767-5p, leading to the up-regulation of suppressors of cytokine signaling 2 (SOCS2) and inactivation of JAK2/STAT5 pathway. Moreover, circNOL10-mediated suppression of malignant phenotypes was attenuated by miR-767-5p. Similar to circNOL10, enforced expression of SOCS2 also resulted in the suppression of cell proliferation and metastasis. Furthermore, knockdown of SOCS2 reversed the tumor-suppressive effect induced by circNOL10. CONCLUSIONS: CircNOL10 repressed BC development via inactivation of JAK2/STAT5 signaling by regulating miR-767-5p/SOCS2 axis. Our findings offer the possibility of exploiting circNOL10 as a therapeutic and prognostic target for BC patients.

Exosome-mediated lncRNA AFAP1-AS1 promotes trastuzumab resistance through binding with AUF1 and activating ERBB2 translation.

BACKGROUND: Although trastuzumab provides significant clinical benefit for HER2-positive breast cancers, responses are limited by the emergence of resistance. Recent evidence suggests that long noncoding RNAs (lncRNAs) play important roles in tumorigenesis and chemoresistance. However, the regulatory mechanism of lncRNAs in trastuzumab resistance is not well established to date. In this research, we identified the differentially expressed lncRNA and investigated its regulatory role in trastuzumab resistance of breast cancer. METHODS: LncRNA microarray and qRT-PCR were performed to identify the dysregulated lncRNAs. Transmission electron microscopy, differential ultracentrifugation and qRT-PCR were used to verify the existence of exosomal AFAP1-AS1 (actin filament associated protein 1 antisense RNA 1). Bioinformatics prediction, RNA fluorescence in situ hybridization (RNA-FISH) and immunoprecipitation assays were performed to identify the direct interactions between AFAP1-AS1 and other associated targets, such as AU-binding factor 1 (AUF1) and ERBB2. Finally, a series gain- or loss-functional assays were done to prove the precise role of AFAP1-AS1 in trastuzumab resistance. RESULTS: AFAP1-AS1 was screened out due to its higher expression in trastuzumab-resistant cells compared to sensitive cells. Increased expression of AFAP1-AS1was associate with poorer response and shorter survival time of breast cancer patients. AFAP1-AS1 was upregulated by H3K27ac modification at promoter region, and knockdown of AFAP1-AS1 reversed trastuzumab resistance. Moreover, extracellular AFAP1-AS1 secreted from trastuzumab resistant cells was packaged into exosomes and then disseminated trastuzumab resistance of receipt cells. Mechanically, AFAP1-AS1 was associated with AUF1 protein, which further promoted the translation of ERBB2 without influencing the mRNA level. CONCLUSION: Exosomal AFAP1-AS1 could induce trastuzumab resistance through associating with AUF1 and promoting ERBB2 translation. Therefore, AFAP1-AS1 level may be useful for prediction of trastuzumab resistance and breast cancer treatment.

CircZFR functions as a sponge of miR-578 to promote breast cancer progression by regulating HIF1A expression.

BACKGROUND: Breast cancer (BC) is the most common malignancy among women. Emerging studies have demonstrated that circular RNA (circRNA) zinc finger RNA binding protein (circZFR) serves as a crucial regulator in many human cancers. However, the role and mechanism of circZFR in BC tumorigenesis remain unclear. METHODS: The levels of circZFR, miR-578 and hypoxia-inducible factor 1α (HIF1A) were detected by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot. Cell viability, colony formation, apoptosis, migration and invasion capacities in vitro were determined by using the Cell Counting Kit-8 (CCK-8), standard colony formation, flow cytometry and transwell assays, respectively. Glucose uptake, lactate product and adenosine triphosphate (ATP) levels of cells in vitro were measured using the commercial human assay kits. Targeted relationships among circZFR, miR-578 and HIF1A in BC cell lines were verified by dual-luciferase reporter and RNA pulldown assays. Animal studies were performed to assess the effect of circZFR on tumor growth in vivo. RESULTS: Our data indicated that circZFR was overexpressed in BC tissues and cells, and the increased circZFR level predicted poor prognosis of BC patients. CircZFR silencing or miR-578 overexpression repressed BC cell viability, colony formation, migration, invasion, and glycolysis and enhanced cell apoptosis in vitro. CircZFR silencing also hampered tumor growth in vivo. Mechanistically, circZFR acted as a sponge of miR-578, and circZFR silencing hindered BC cell malignant behaviors by miR-578. HIF1A was a functional target of miR-578 in regulating BC cell viability, colony formation, migration, invasion, glycolysis and apoptosis in vitro. Furthermore, circZFR modulated HIF1A expression through sponging miR-578. CONCLUSION: Our findings first identified that the silencing of circZFR suppressed BC malignant progression in vitro via the regulation of the miR-578/HIF1A axis, providing evidence for the crucial involvement of circZFR in BC pathogenesis.

CircUBE2D2 (hsa_circ_0005728) promotes cell proliferation, metastasis and chemoresistance in triple-negative breast cancer by regulating miR-512-3p/CDCA3 axis.

BACKGROUND: Triple-negative breast cancer (TNBC) is a clinically aggressive subtype of breast cancer with a bad prognosis. Chemotherapy is still the standard of care for TNBC treatment. Circular RNAs (CircRNAs) have been recently discovered to be closely involved in the initiation and development of human cancers. Herein, we focus our attention on the functions and underlying mechanisms of circUBE2D2 in TNBC progression and chemoresistance. METHODS: The expression of circUBE2D2, miR-512-3p, and cell division cycle associated 3 (CDCA3) mRNA were determined by qRT-PCR. CCK-8, colony formation, transwell and flow cytometry assays were performed to detect cell proliferation, migration, invasion and apoptosis. Western blot assay was utilized to measure the protein level of CDCA3. RNA pull-down, luciferase reporter and RIP experiments were employed to examine the possible regulatory mechanism of circUBE2D2. RESULTS: CircUBE2D2 expression was elevated in TNBC tissues and cells. TNBC patients with high circUBE2D2 expression are inclined to present advanced TNM stage, lymph node metastasis and adverse prognosis. Knockdown of circUBE2D2 repressed cell proliferation, migration and invasion in vitro, and impeded tumor growth in vivo. Moreover, silencing of circUBE2D2 reduced doxorubicin resistance of TNBC cells. In-depth mechanism analysis revealed that circUBE2D2 served as a miRNA sponge to protect CDCA3 from the attack of miR-512-3p. Additionally, the tumor-suppressive effect induced by circUBE2D2 depletion was greatly impaired upon miR512-3p down-regulation or CDCA3 overexpression. Also, depletion of circUBE2D2 decreased the resistance to doxorubicin through regulating miR-512-3p/CDCA3 axis. CONCLUSION: CircUBE2D2 promoted TNBC progression and doxorubicin resistance through acting as a sponge of miR-512-3p to up-regulate CDCA3 expression. Targeting circUBE2D2 combine with doxorubicin might be exploited as a novel therapy for TNBC.

Inhibitory role of large intergenic noncoding RNA-ROR on tamoxifen resistance in the endocrine therapy of breast cancer by regulating the PI3K/Akt/mTOR signaling pathway.

Breast cancer (BC) is the second-leading cause of central nervous system metastases among severe malignancies. This study aimed at investigating the underlying mechanism by which large intergenic noncoding RNA-regulator of reprogramming (lincRNA-ROR) affects the tamoxifen (TAM) resistance of BC cells by regulating the PI3K/Akt/mTOR signaling pathway. Immortalized human mammary epithelial cell line (MCF10A) and BC cell lines (MCF-7, MDA-MB-231, T47D, BCAP-37, and ZK-75-1) were cultured, and BC tissues and adjacent normal breast tissues were collected from 152 BC patients. LincRNA-ROR expression in tissues and cells were detected using reverse transcription quantitative polymerase chain reaction. RNA interference was used to silence lincRNA-ROR in MDA-MB-231 cells, and then the cell proliferation and apoptosis were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and annexin-V and propidium iodide (PI) double staining respectively. The expression of apoptosis-related proteins and PI3K/Akt/mTOR signaling pathway-related proteins was measured by performing western blot assay. The BC tissues and cells presented a higher expression of lincRNA-ROR. MAD-MB-231 cells exhibited the highest lincRNA-ROR expression. After lincRNA-ROR silencing, MAD-MB-231 cells showed decreased proliferation, and increased sensitivity to TAM. Besides, the apoptosis-promoting effect of TAM on MAN-MB-231 cells significantly increased. The expression of PI3K/Akt/mTOR signaling pathway-related proteins and the PI3K/Akt/mTOR signaling pathway were repressed by TAM after silencing lincRNA-ROR. Our study demonstrated that silencing lincRNA-ROR could increase the sensitivity of BC MAD-MB-231 cells to TAM by suppressing the activation of P13K/Akt/mTOR signaling pathway.

LINC01857 as an oncogene regulates CREB1 activation by interacting with CREBBP in breast cancer.

Breast cancer is a one of the most malignant threats among women worldwide. However, the mechanism underlying breast cancer development remains unclear. Long noncoding RNAs (lncRNAs) have been reported to participate in breast cancer. Whether lncRNA LINC01857 is involved in breast cancer requires investigation. In this study, we found that LINC01857 was highly expressed in breast cancer tissues and cells (p < 0.05). High LINC01857 expression predicted poor prognosis in breast cancer patients. Functionally, LINC01857 silencing impaired proliferation and enhanced apoptosis of breast cancer cells ( p < 0.05). Decreased LINC01857 inhibited breast cancer cells migration and invasion ability ( p < 0.05). In terms of mechanism, LINC01857 promoted H3K27Ac deposition on CREB1 promoter and initiated its transcription by recruiting CREBBP. Overexpression of CREB1 reversed the biological behavior of breast cancer cells induced by LINC01857 silencing ( p < 0.05). Taken together, our findings demonstrated that LINC01857 promoted breast cancer development by promoting H3K27Ac and CREB1 transcription via enhancing CREBBP enrichment in the CREB1 promoter region.

MEG3 overexpression inhibits the tumorigenesis of breast cancer by downregulating miR-21 through the PI3K/Akt pathway.

Increasing studies have highlighted the critical role of lncRNAs in cancer pathogenesis and development. LncRNA maternally expressed gene 3 (MEG3) was reported to function as a tumor suppressor in breast cancer. However, the detailed molecular mechanism of MEG3 involved in breast cancer progression remains far from being addressed. Our findings showed that MEG3 was downregulated and miR-21 was upregulated in breast cancer patient tissues and cells. MEG3 overexpression suppressed cell proliferation and glycolysis, and induced apoptosis in breast cancer cells. MEG3 was demonstrated to function as a molecular sponge of miR-21 and suppress its expression. Moreover, miR-21 upregulation partially abolished the effects of MEG3 overexpression on cell proliferation, glycolysis, and apoptosis in breast cancer cells. Additionally, enforced expression of MEG3 reversed miR-21-mediated activation of PI3K/Akt pathway in breast cancer cells. In vivo experiment demonstrated that overexpression of MEG3 inhibited tumor growth in breast cancer by suppressing miR-21. In summary, MEG3 overexpression inhibited the tumorigenesis of breast cancer by downregulating miR-21 through the PI3K/Akt pathway.

Effects of long non-coding RNA HOST2 on cell migration and invasion by regulating MicroRNA let-7b in breast cancer.

The study intends to investigate the effects of long non-coding RNA HOST2 (lncRNA HOST2) on cell migration and invasion by regulating microRNA let-7b (let-7b) in breast cancer. Breast cancer and adjacent normal tissues were collected from 98 patients with breast cancer. Breast cancer MCF-7 cells were divided into the blank, negative control (NC), pcDNA3-Mock, siHOST2, let-7b inhibitor, pcDNA3-HOST2, let-7b mimic, pcDNA3-HOST2 + let-7b mimic, and siHOST2 + let-7b inhibitor groups. RT-qPCR was used to detect the mRNA expressions of HOST2, let-7b, and c-Myc. Western blotting was conducted to measure the c-Myc expression. Scratch test and Transwell assay were applied to detect the cell motility, migration, and invasion. Xenograft tumor in nude mice was performed to evaluate the effect of different transfection on the tumor growth. Compared with adjacent normal tissues, HOST2 expression was higher but let-7b expression lower in breast cancer tissues. HOST2 expression in breast cancer cells was remarkably increased compared with that in the normal breast epithelial MCF-10A cells. In MCF-7 cells, in comparison with the blank and NC groups, expressions of HOST2 and c-Myc were reduced, but let-7b expression was remarkably elevated in the siHOST2 and let-7b mimic groups; the let-7b inhibitor group exhibited higher expressions of HOST2 and c-Myc but lower let-7b expression. Overexpression of HOST2 could promote cell motility, migration and invasion, thus enhancing the growth of breast cancer tumor. By inhibiting HOST2, opposite trends were found. LncRNA HOST2 promotes cell migration and invasion by inhibiting let-7b in breast cancer patients.

microRNA-30d mediated breast cancer invasion, migration, and EMT by targeting KLF11 and activating STAT3 pathway.

miR-30d has been shown to play pivotal roles in cancer development, and has the potential to act as a diagnostic biomarker and therapeutic target in breast cancer. However, the specific function and molecular mechanism of miR-30d in breast cancer cell growth and metastasis is still unknown. The present study seeks to shed light on the potential contribution of the MiR-30d-KLF-11-STAT3 pathway in breast cancer. The results revealed that miR-30d levels were markedly increased in the breast cancer cell lines BT474, MDA-MB-231, HCC197, and MDA-MB-468 compared with the non-tumor mammary gland MCF10A cell line. Furthermore, the miR-30d mimic increased BT474 and MDA-MB-231 breast cancer cell survival, inhibited apoptosis and increased Bcl-2 expression, whilst inhibited Bax protein levels. miR-30d mimics promote BT474 and MDA-MB-231 cell migration, invasion, and mediate the EMT phenotype. However, miR-30d inhibitors reverse all of the effects of miR-30d mimics on breast cancer cell biology. Also, we observed that KLF-11 is a direct target of miR-30d and KLF-11 and pSTAT3 expression are determined by miR-30d. Finally, the results suggest that miR-30d plays essential roles in breast cancer cells in a manner that is dependent on the levels of KLF-1 and pSTAT3. In summary, miR-30d appears to be a novel diagnostic biomarker and treatment target in breast cancer.

Circular RNA circMYO9B facilitates breast cancer cell proliferation and invasiveness via upregulating FOXP4 expression by sponging miR-4316.

Recently, circular RNAs (circRNAs) have been demonstrated as essential regulators in human cancers. However, the function and mechanism of circRNAs in breast cancer (BC) remain largely unknown and require to be investigated. In the present study, we found that circMYO9B was highly expressed in BC tissues by bioinformatics analysis. And we showed that circMYO9B expression was positively correlated with patients' prognosis. Moreover, we found that circMYO9B knockdown significantly suppressed the proliferation, migration and invasion of BC cells in vitro. In vivo assays also indicated that circMYO9B silence delayed tumor growth. In mechanism, we found that circMYO9B promoted the expression of FOXP4 by sponging miR-4316 in BC cells. We showed that the expression of miR-4316 was inversely associated with that of circMYO9B or FOXP4 in BC tissues. Finally, we found that restoration of FOXP4 expression significantly reversed the effects of circMYO9B knockdown on BC cell proliferation, migration and invasion. In conclusion, our findings demonstrated a key role of circMYO9B/miR-4316/FOXP4 axis in regulating BC progression.

Sonic hedgehog stimulates glycolysis and proliferation of breast cancer cells: Modulation of PFKFB3 activation.

Sonic hesgehog (Shh) signaling has been reported to play an essential role in cancer progression. The mechanism of Shh involved in breast cancer carcinogenesis remains unclear. The present study sought to explore whether Shh signaling could regulate the glycolytic metabolism in breast cancers. Overexpression of the smoothed (Smo) and Gli-1 was found in human primary breast cancers. The expressions of Shh and Gli-1 correlated significantly with tumor size and tumor stage. In vitro, human recombinant Shh (rShh) triggered Smo and Gli-1 expression, promoted glucose utilization and lactate production, and accelerated cell proliferation in MCF-7 and MDA-MB-231 cells. Notably, rShh did not alter 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3) expression but augmented PFKFB3 phosphorylation on ser(461), along with elevated fructose-2,6-bisphosphate (F2,6BP) generation by MCF-7 and MDA-MB-231 cells. This effect could be dampened by Smo siRNA but not by Gli-1 siRNA. In addition, our data showed the upregulated expressions of MAPK by rShh and elevatory PFKFB3 phosphorylation by p38/MAPK activated kinase (MK2). In conclusion, our study characterized a novel role of Shh in promoting glycolysis and proliferation of breast cancer cells via PFKFB3 phosphorylation, which was mediated by Smo and p38/MK2.

Overexpression of miR-206 suppresses glycolysis, proliferation and migration in breast cancer cells via PFKFB3 targeting.

miRNAs, sorting as non-coding RNAs, are differentially expressed in breast tumor and act as tumor promoters or suppressors. miR-206 could suppress the progression of breast cancer, the mechanism of which remains unclear. The study here was aimed to investigate the effect of miR-206 on human breast cancers. We found that miR-206 was down-regulated while one of its predicted targets, 6-Phosphofructo-2-kinase (PFKFB3) was up-regulated in human breast carcinomas. 17ß-estradiol dose-dependently decreased miR-206 expression as well as enhanced PFKFB3 mRNA and protein expression in estrogen receptor α (ERα) positive breast cancer cells. Furthermore, we identified that miR-206 directly interacted with 3'-untranslated region (UTR) of PFKFB3 mRNA. miR-206 modulated PFKFB3 expression in MCF-7, T47D and SUM159 cells, which was influenced by 17ß-estradiol depending on ERα expression. In addition, miR-206 overexpression impeded fructose-2,6-bisphosphate (F2,6BP) production, diminished lactate generation and reduced cell proliferation and migration in breast cancer cells. In conclusion, our study demonstrated that miR-206 regulated PFKFB3 expression in breast cancer cells, thereby stunting glycolysis, cell proliferation and migration.