BCAR4 facilitates trastuzumab resistance and EMT in breast cancer via sponging miR-665 and interacting with YAP1

Breast cancer antiestrogen resistance 4 (BCAR4) has been suggested that can modulate cell behavior, resulting in tumorigenesis and chemoresistance. However, the underlying mechanisms of BCAR4 in trastuzumab resistance (TR) is still elusive. Here, we explored the function and the underlying mechanism of BCAR4 involving in TR. We found that BCAR4 is significantly upregulated in trastuzumab-resistant BC cells. Knockdown of BCAR4 could sensitize the BC cells to trastuzumab and suppress epithelial-mesenchymal transition (EMT). Mechanically, BCAR4 promotes yes-associated protein 1 (YAP1) expression by competitively sponging miR-665, to activated TGF-β signaling. Reciprocally, YAP1 could occupy the BCAR4 promoter to enhance its transcription, suggesting that there exists a positive feedback regulation between YAP1 and BCAR4. Targeting the BCAR4/miR-665/YAP1 axis may provide a novel insight of therapeutic approaches for TR in BC.

Long Non-Coding RNA BCAR4 Promotes Oxaliplatin Resistance in Colorectal Cancer by Modulating miR-484-3p/RAB5C Expression

BACKGROUND

Oxaliplatin-based chemotherapy resistance is a major cause of recurrence in patients with colorectal cancer (CRC). Increasing evidence indicates that lncRNA BCAR4 is involved in the occurrence and development of various cancers. However, the effect of BCAR4 on CRC chemotherapy resistance remains unclear.

METHODS

Real-time quantitative PCR and Western blotting were used to detect the expression levels of gene and protein, respectively. The role of BCAR4 in drug resistance was evaluated by cell viability and apoptosis experiments. Luciferase reporter assay and Western blot analysis confirmed the relationship between BCAR4, miR-483-3p, and RAB5C.

RESULTS

Luciferase reporter assay and Western blotting analysis confirmed the relationship among BCAR4, miR-483-3p, and RAB5C. The results showed that the expression levels of BCAR4 and RAB5C were increased in CRC tumor tissue. The expression levels of BCAR4 were increased in patients with chemotherapy resistance. Functional analysis showed that knockdown of BCAR4 reduced the expression levels of proteins related to stemness, decreased the activity of cells, and promoted apoptosis of CRC cells, while overexpression of RAB5C reversed these effects. Moreover, the results showed that BCAR4 promoted oxaliplatin resistance by inhibiting cell apoptosis. Mechanistically, BCAR4 sponged miR-483-3p and promoted the expression of RAB5C. Knockdown of BCAR4 reduced tumor size and enhanced cell sensitivity to oxaliplatin in vivo.

CONCLUSION

The results suggested that BCAR4/miR-483-3p/RAB5C axis has the potential to be explored as a novel therapeutic target for CRC treatment.

Downregulation of long noncoding RNA breast cancer anti-estrogen resistance 4 inhibits cell proliferation, invasion, and migration in esophageal squamous cell carcinoma by regulating the microRNA-181c-5p/LIM and SH3 protein 1 axis

Recently, abnormal expression of long non-coding RNAs (lncRNAs) has been observed in esophageal squamous cell carcinoma (ESCC). In various human cancers, breast cancer anti‑estrogen resistance 4 (BCAR4) was reported to be highly expressed, while the biological roles of BCAR4 in ESCC remain unclear. In ESCC cells and tissues, BCAR4 and microRNA −181c-5p (miR-181c-5p) expression, and phosphorylated signal transducer and activator of transcription (p-STAT3) and COX2 expression were evaluated by real-time reverse transcription PCR (qRT-PCR) and Western blot analysis. Cell function was evaluated by colony formation, CCK-8 assay, transwell and flow cytometer assays. Interactions between BCAR4 and miR-181c-5p, as well as miR-181c-5p and LIM and SH3 protein 1 (LASP1) were evaluated by RIP and luciferase reporter assay. ESCC cell malignancy with inhibition of BCAR4 was confirmed by a tumor xenograft model in vivo. In both ESCC tissues and cell lines, BCAR4 was upregulated. Downregulation of BCAR4 effectively induced cell apoptosis and inhibited invasion and migration in vitro, and reduced tumorigenesis in nude mice. BCAR4 was a sponge of miR-181c-5p to upregulate LASP1. Moreover, knockdown of BCAR4 and overexpression of miR-181c-5p inhibited the activation of the STAT3/COX2 signaling, which was reversed by overexpression of LASP1. In conclusion, BCAR4 promotes ESCC tumorigenesis by targeting the miR-181c-5p/LASP1 axis, which may act as a treatment and diagnosis biomarker for ESCC.

The functional role of oncogenic lncRNA BCAR4 for cancer outcome

BACKGROUND

Long non-coding RNA (lncRNA) breast cancer anti-estrogen resistance 4 (BCAR4) is a characterized oncogenic lncRNA in different cancers. This review is dedicated to summarize various molecular mechanisms of BCAR4 and demonstrate that the biological functions exerted by BCAR4 are good entry points for therapy.

METHODS

The molecular mechanism of BCAR4 acting on tumors is summarized by reviewing PubMed.

RESULTS

The expression of lncRNA BCAR4 is abnormally increased in all kinds of tumors, including colorectal cancer, prostate cancer, bladder cancer, gastric cancer, chondrosarcoma, glioma, breast cancer, glioma, gastric cancer, liver cancer, cervical cancer, lung cancer, etc. Besides, BCAR4 mediates multiple processes involved in carcinogenesis, including proliferation, invasion, anti-apoptosis, migration.

CONCLUSION

BCAR4 may show great clinical value in this direction as a therapeutic cancer target.

The role of long non-coding RNA BCAR4 in human cancers

Long non-coding RNA (lncRNA) is a type of non-coding RNA with length of nucleotides > 200 bp. Increasing evidences show that lncRNA breast cancer antiestrogen resistance 4 (BCAR4) plays an important role in the occurrence and development of various human cancers. It is found that BCAR4 is highly expressed in diverse tumor tissues and cells, and the high expression of BCAR4 is usually associated with poor prognosis. BCAR4 is considered as an oncogene in human cancers. By competing endogenous RNA (ceRNA) mechanism and regulating different signaling pathways, BCAR4 participates in the proliferation, apoptosis, migration, invasion, epithelial-mesenchymal transition (EMT), metastasis and tumorigenesis of different cancers. In addition, overexpression of BCAR4 promotes drug resistance of tumor cells. Therefore, BCAR4 is a promising biomarker for cancer diagnosis and prognosis, and it is a potential target for cancer therapy. This paper reviews studies focusing on the relationship between BCAR4 and cancers in recent years and aims to summarize the effect and mechanism of BCAR4 in human cancers.

Variant in BCAR4 gene correlated with the breast cancer susceptibility and mRNA expression of lncRNA BCAR4 in Chinese Han population

BACKGROUND

Long non-coding RNA (LncRNA) Breast cancer anti-estrogen resistance 4 (BCAR4) has been shown to participate in the biological progress of various cancers including breast cancer. Genetic Polymorphisms in BCAR4 may have an influence on the progress of breast cancer, but it is rarely studied.

METHODS

In our epidemiology study, three tagging SNPs (rs4561483, rs11649623 and rs13334967) in lncRNA BCAR4 were selected for genotyping among 487 breast cancer cases and 489 healthy controls. And quantitative real-time PCR (qRT-PCR) was performed to evaluate the relative mRNA expression of BCAR4 in different genotypes of the significant locus rs13334967.

RESULTS

We found that BCAR4 rs13334967 is associated with lower breast cancer risk both in codominant model (AT vs AA, OR 0.632, 95% CI 0.429-0.931, TT vs AA, OR 0.731, 95% CI 0.511-0.990) and dominant model (AT + TT vs AA, OR 0.798, 95% CI 0.571-0.970). The further results of qRT-PCR displayed that carriers with rs13334967 AT, TT genotype have lower BCAR4 mRNA expression compared with AA genotype.

CONCLUSION

The research study implied that BCAR4 rs13334967 was correlated with the susceptibility to breast cancer and may impact the mRNA expression of BCAR4. LncRNA BCAR4 may be a potential biomarker and therapeutic target for breast cancer.

Long non-coding RNA BCAR4 promotes liver cancer progression by regulating proliferation, migration and invasion

Liver cancer (LC) is one of the primary contributors of cancer-associated death worldwide. Long non-coding RNAs (lncRNAs) have been shown to participate in almost every aspect of cell biology and serve fundamental roles in carcinogenesis and cancer progression, including in LC. However, the clinical significance and functional role of the lncRNA breast cancer anti-estrogen resistance 4 (BCAR4) in LC have not yet been identified. The present study measured the expression levels of BCAR4 in LC cells and tissues, and discovered that BCAR4 was upregulated in LC tissues compared with adjacent normal tissues. Furthermore, high BCAR4 expression was associated with the presence of multiple tumors and advanced Tumor-Node-Metastasis stages (III/IV). Survival analysis found that high BCAR4 expression indicated poor overall survival (OS) and progression-free survival (PFS). By analyzing the risk factors of poor OS and PFS using univariate analysis and multivariate analysis, high BCAR4 expression was revealed to be an independent risk factor of poor prognosis. In addition, the role of BCAR4 was further investigated in vitro, which revealed overexpression of BCAR4 to markedly promote the proliferation, migration and invasion of LC cells. Conversely, the loss of BCAR4 expression repressed the proliferation, migration and invasion of LC cells. In conclusion, BCAR4 is overexpressed in LC and is associated with LC progression. Therefore, BCAR4 may be used as a potential prognostic marker in LC.

Long Non-Coding RNA BCAR4 Binds to miR-644a and Targets TLX1 to Promote the Progression of Bladder Cancer

Background

Bladder cancer is a serious threat to human health. It is meaningful to study the pathogenesis of bladder cancer. Long non-coding RNAs (lncRNAs) are reported to promote or inhibit bladder cancer development. However, the role of lncRNA BCAR4 in the regulation of bladder cancer remains unclear.

Purpose

This study was to explore the role of lncRNA BCAR4 in the progression of bladder cancer cell.

Methods

RT-PCR was used to examine the expression of BCAR4 and miR-644a. CCK8 assay, colony formation assay, Transwell assay were used to detect the progression of bladder cancer cells after transfecting of indicated plasmids.

Results

The expression of BCAR4 was higher in bladder cancer cell lines than normal urothelial cell line. Moreover, the expression of BCAR4 was associated with the advanced stage and metastasis of bladder cancer. Through knockdown of BCAR4, we discovered that knockdown of BCAR4 significantly decreased the proliferation, migration and invasive abilities of bladder cancer cells. Mechanically, we showed that BCAR4 can bind to miR-644a directly and targets TLX1. Moreover, we also showed that miR-644a was also highly expressed in bladder cancer cells and inhibition of miR-644a or overexpression of TLX1 can increased the migration abilities of bladder cancer caused by knockdown of BCAR4.

Conclusion

We showed that BCAR4 sponged miR-644a to modulate the expression of TLX1 and promote bladder cancer development.

Long Non-Coding RNA BCAR4 Promotes Growth, Invasion and Tumorigenicity by Targeting miR-2276 to Upregulate MMP7 Expression in Glioma

Objective

Long non-coding RNA breast cancer anti-estrogen resistance 4 (BCAR4) has been recognized as a proto-oncogene in various malignancies. It has been reported to be highly expressed and promote cell proliferation in glioma. However, its additional roles in gliomagenesis remain largely unclear. This research intends to investigate the impact and internal molecular mechanism of BCAR4 on glioma cell growth, invasion and tumorigenesis.

Methods

BCAR4 expression was examined by qPCR in 30 cases of graded glioma specimens and 7 glioblastoma (GBM) cell lines compared with respective controls. Its potential prognostic value was evaluated by Kaplan-Meier survival analysis. The biological roles of BCAR4 in gliomagenesis were verified by CCK-8, transwell and intracranial xenograft assays successively. qPCR and RNA pull-down assays were applied to study the relationship between BCAR4 and miR-2276. Then, qPCR, Western blot and luciferase reporter assays were used to validate the targeting of matrix metallopeptidase 7 (MMP7) by miR-2276 and the regulation of MMP7 by BCAR4. Finally, MMP7 was restored in BCAR4-silenced GBM cells and the rescue effects were determined by CCK-8 and transwell assays.

Results

BCAR4 expression was increased in glioma tissues and GBM cell lines, and its high expression positively correlated with advanced grades and worse prognosis. Functional assays verified that knockdown of BCAR4-inhibited cell growth and invasion in vitro, and impaired tumor formation in vivo. Mechanistically, we found that BCAR4 could act as a competing endogenous RNA (ceRNA) by targeting miR-2276 to upregulate MMP7 expression. Importantly, MMP7 restoration effectively rescued the inhibitory modulations on GBM cell growth and invasion caused by BCAR4 knockdown.

Conclusion

Our findings identified the essential roles of the BCAR4/miR-2276/MMP7 axis in gliomagenesis and provided novel insights on glioma therapy.

BCAR4 activates GLI2 signaling in prostate cancer to contribute to castration resistance

Long non-coding RNAs (lncRNAs) have been found essential for tumorigenesis of prostate cancer (PC), but its role in the regulation of castration-resistant prostate cancer (CRPC) is poorly identified. Here, we showed that a lncRNA, Breast-Cancer Anti-Estrogen Resistance 4 (BCAR4), which plays a pivotal role in the tamoxifen-resistance of breast cancer, was significantly upregulated in CRPC, but not in castration-sensitive prostate cancer (CSPC), compared to normal prostate tissue. High BCAR4 levels in CRPC were correlated with poor patients' overall survival. Androgen increased growth and migration of androgen receptor (AR)-positive PC346 cells, which was abolished by the antagonist of androgen. Overexpression of BCAR4 in PC346 cells increased cell growth and migration, but turned the cells insensitive to androgen. On the other hand, growth and migration of AR-negative DU145 cells are insensitive to androgen, while depletion of BCAR4 in DU145 cells not only decreased cell growth, but also turned the cells sensitive again to androgen. Moreover, BCAR4 activated GLI2 downstream genes, and correlated with the levels of these GLI2-target genes in CRPC. Depletion of GLI2 abolished the effects of BCAR4 on cell growth and migration. Together, our data suggest that BCAR4 may activate GLI2 signaling in PC to contribute to castration resistance.

The Value of LncRNA BCAR4 as a Prognostic Biomarker on Clinical Outcomes in Human Cancers

Background: This updated meta-analysis aimed to analyze available data to explore the prognostic value of long noncoding RNA breast cancer anti-estrogen resistance 4 (BCAR4) in various human malignancies. Methods: Literature retrieval was performed by systematic searching several authoritative databases, including Pubmed, PMC database, Web of Science, the Cochrane Library, Embase, and CNKI database up to Feb 10, 2019. Data were extracted and subsequently crosschecked, and discrepancies were discussed to reach consensus. Quality of the eligible studies was evaluated by Newcastle-Ottawa Scale (NOS). The fixed- or random-effects model was used to calculate the pooled the hazard ratios (HRs) or odds ratios (ORs) and the 95% confidence interval (95% CI). Publication bias was detected by using Begg's funnel plot and Egger's test. Results: A total 1,128 cancer patients from thirteen studies were included and pooled in the present meta-analysis. High expression levels of BCAR4 were correlated with unfavorable overall survival (OS) (HR=2.23, 95% CI: 1.84-2.71), but not progression-free survival (PFS) (HR=1.30, 95% CI: 0.80-2.11). Subgroup stratified analysis showed that tumor type, sample size, follow-up months, and survival analysis method did not alter the predictive value of BCAR4 on OS in various cancers. Furthermore, elevated BCAR4 level was markedly correlated with advanced clinical stage (III/IV) (OR=3.28, 95% CI: 2.33-4.60), and dramatically predicted lymph node metastasis (OR=3.00, 95% CI: 1.95-4.63, P<0.00001) and distant metastasis (OR=3.36, 95% CI: 1.88-5.98, P<0.0001), but not associated with age, gender or tumor size. No obvious heterogeneity was noted for correlation between BCAR4 expression and OS across these studies. Conclusions: High expression of BCAR4 was correlated with unfavorable overall survival outcome and clinical features including metastasis and progression, implicating an independent prognostic value for BCAR4 in human cancers.

Long noncoding RNA Breast cancer antiestrogen resistance 4 is associated with cancer progression and its significant prognostic value

Breast cancer antiestrogen resistance 4 (BCAR4) is a novel long noncoding RNA. It was originally identified in a screen for genes responsible for the development of resistance to antiestrogens in breast cancer cells and plays a major role in various tumors. However, the clinical diagnostic role of BCAR4 in tumors is not completely understood. This current meta-analysis aimed to comprehensively explore the potential role of BCAR4 as a prognostic biomarker in a number of cancers. Five public databases PubMed, EMBASE, Web of Science, Wiley Online Library, and Medline were used to search for articles. Nine studies comprising 1,293 patients were included in this meta-analysis. The results of analysis showed that BCAR4 expression in human cancer was significantly associated with poor overall survival (hazard ratio [HR] = 1.98, confidence interval [CI]: [1.71-2.29]), p < 0.00001, and high BCAR4 expression was associated with clinical stage (OR and its 95% CI was 3.30 [1.99-5.46], p < 0.00001), distant metastasis (OR = 3.83, 95% CI: 2.15-6.82, p < 0.00001), and lymph node metastasis (OR and its 95% CI was 2.91 [1.62-5.25], p = 0.0004) in patients with cancer. Furthermore, the results revealed the prognostic significance of BCAR4 in gastrointestinal malignancy, breast cancer, and osteosarcoma (HR and its 95% CI were 2.05 [1.56-2.68], p < 0.00001; 1.78 [1.46-2.16], p < 0.00001; and 2.47 [1.41-4.34], p < 0.00001, respectively). This meta-analysis indicated the potential value of BCAR4 as a biomarker for predicting a poor prognosis in patients with cancer.

Up-regulated BCAR4 contributes to proliferation and migration of cervical cancer cells

OBJECTIVES

Recently, thousands of long non-coding RNAs (lncRNAs) involved in development and metastasis of malignant tumors have been identified. Long non-coding RNA (lncRNA) breast cancer anti-estrogen resistance 4 (BCAR4) has been proved to promote proliferation and metastasis in multiple tumors. However, the function and significance of BCAR4 in cervical cancer are still unclear.

METHODS

In this study, we concentrated on the biological function and clinical significance of BCAR4 in cervical cancer. More specifically, BCAR4 expression was evaluated in cervical cancer tissues and cell lines by qRT-PCR. Moreover, the prognostic factors were assessed by Kaplan-Meier analysis and Cox proportional hazards models. Additionally, functional assays were conducted and the potential mechanism was explored.

RESULTS

Our study showed that BCAR4 expression was significantly up-regulated in cervical cancer tissue and cell lines. Moreover, patients with high BCAR4 expression showed worse survival outcomes and overexpression of BCAR4 might be an independent prognostic factor in cervical cancer. Furthermore, overexpression of BCAR4 remarkably promoted the proliferation, motility of cervical cancer cells and silencing BCAR4 significantly suppressed the proliferation, migration and invasion of cervical cancer cells. Additionally, overexpression of BCAR4 promoted epithelial-mesenchymal transition (EMT) process and silencing BCAR4 suppressed EMT process in cervical cancer cells.

CONCLUSIONS

The results indicated that BCAR4 might play a crucial role in cervical cancer progression and act as an underlying biomarker for the diagnosis and prognosis of cervical cancer.

LncRNA BCAR4 promotes colon cancer progression via activating Wnt/β-catenin signaling

BCAR4 (Breast Cancer Anti-Estrogen Resistance 4) is a long noncoding RNA that was identified as an oncogene in breast cancer. In our research, we found that the expression level of BCAR4 was upregulated in colon cancer tissues compared to paired normal tissues. What's more, higher BCAR4 expression was correlated with lower survival rate in patients with colon cancer. Mechanistically, we showed that BCAR4 activated Wnt/β-catenin signaling in colon cancer by protecting β-catenin from degradation. We also showed that BCAR4 overexpression promoted cell proliferation and migration in colon cancer. However, silencing BCAR4 inhibited cell growth and promoted apoptosis. Besides, BCAR4 knockdown decreased tumor growth in vivo. These findings indicate that BCAR4 facilitated colon cancer progression by enhancing cell proliferation and inhibiting apoptosis via BCAR4/β-catenin axis. BCAR4 may be a useful new target for treatment of patients with colon cancer.

Long non-coding RNA BCAR4 promotes chondrosarcoma cell proliferation and migration through activation of mTOR signaling pathway

BACKGROUND

Chondrosarcoma is one of the common malignant histologic tumors, very difficult to treat, but the concrete cause and mechanism have not yet been elucidated. The present study aimed to investigate the functional involvement of BCAR4 in chondrosarcoma and its potentially underlying mechanism. QRT-PCR and western blot were used to determine the expression of BCAR4 and mTOR signaling pathway proteins both in chondrosarcoma tissues and cells. Chondrosarcoma cell proliferation and migration were assessed by MTT assay and transwell migration assay, respectively. The expression vectors were constructed and used to modulate the expression of BCAR4 and mTOR. Chondrosarcoma xenograft mouse model was established by subcutaneous injection with chondrosarcoma cell lines. The tumor volume was monitored to evaluate the effect of BCAR4 on chondrosarcoma cell tumorigenicity. The expressions of BCAR4, p-mTOR and p-P70S6K were up-regulated in chondrosarcoma tissues and cell lines. Moreover, BCAR4 overexpression had significant promoting effect on cell proliferation and migration in chondrosarcoma cells. Furthermore, mTOR signaling pathway was epigenetically activated by BCAR4-induced hyperacetylation of histone H3. We also found that mTOR overexpression abolished the decrease of chondrosarcoma cell proliferation and migration induced by BCAR4 knockdown. In vivo experiments confirmed that BCAR4 overexpression significantly accelerated tumor growth, while the knockdown of BCAR4 significantly inhibited tumor growth. BCAR4 promoted chondrosarcoma cell proliferation and migration through activation of mTOR signaling pathway, and thus contributed to chondrosarcoma progression. Impact statement LncRNA BCAR4 promoted chondrosarcoma cell proliferation and migration through activation of mTOR signaling pathway, and thus contributed to chondrosarcoma progression.

Unraveling the therapeutic potential of the LncRNA-dependent noncanonical Hedgehog pathway in cancer

Acquired resistance to Hedgehog pathway inhibitors has been reported in the clinical setting and upregulation of noncanonical Hedgehog signaling is one of the major underlying mechanisms behind this resistance. As demonstrated in our recent study, greater clinical efficacy might be achieved by focusing on downstream targets of the chemokine-activated noncanonical Hedgehog signaling pathway such as BCAR4 and phospho-GLI2 (Ser149).