BTG2 inhibits the proliferation, invasion, and apoptosis of MDA-MB-231 triple-negative breast cancer cells

BTG2-deficient mast cells remodel the tumor and tumor-draining lymph node microenvironment leading to chemotherapy resistance in breast cancer

Background

Breast cancer is currently the most frequently diagnosed malignancy worldwide, with chemotherapy resistance being a major contributor to breast cancer-related mortality and distant metastasis. The role of lymph nodes as the initial site of immune defense remains controversial, particularly regarding whether complete dissection or preservation is necessary during breast cancer surgery.

Methods

We performed single-cell RNA sequencing (scRNA-seq) on cells derived from metastatic tumor draining lymph nodes and tumor tissue of four breast cancer patients exhibiting either sensitivity or resistance to neoadjuvant chemotherapy (NAC).

Results

Mast cells with low BTG2 expression were identified in the metastatic lymph nodes and in situ tumor of the NAC-resistant group. Mast cells with low BTG2 expression have enhanced migratory capacity and are preferentially recruited to lymph nodes by cytokines such as CCL5, secreted by tumor cells during metastasis. Mechanistically, the mast cells with low BTG2 suppress anti-tumor immunity by inducing Treg cell production through IL-2 secretion, particularly within tumor-draining lymph nodes. Furthermore, the mast cells with low BTG2 promote NAC resistance by inducing fibroblast precursor cells to differentiate into α-SMA-positive fibroblasts via the Tryptase-PAR-2-pERK signaling pathway, leading to excessive collagen fiber production. Finally, we demonstrated that combining radiotherapy upregulating the expression of BTG2 in mast cells with chemotherapy enhances therapeutic efficacy in a murine model.

Conclusions

This study highlights the immunoregulatory role of mast cells in the breast cancer tumor microenvironment and establishes a link between BTG2 expression in mast cells and neoadjuvant chemotherapy response. These findings provide a foundational basis for preserving functional lymph nodes and optimizing combined radiotherapy treatment strategies.

Dynamic analysis of circulating tumor DNA to predict the prognosis and monitor the treatment response of patients with metastatic triple-negative breast cancer: A prospective study

Background

Limited data are available on applying circulating tumor DNA (ctDNA) in metastatic triple-negative breast cancer (mTNBC) patients. Here, we investigated the value of ctDNA for predicting the prognosis and monitoring the treatment response in mTNBC patients.

Methods

We prospectively enrolled 70 Chinese patients with mTNBC who had progressed after ≤2 lines of chemotherapy and collected blood samples to extract ctDNA for 457-gene targeted panel sequencing.

Results

Patients with ctDNA+, defined by 12 prognosis-relevant mutated genes, had a shorter progression-free survival (PFS) than ctDNA- patients (5.16 months vs. 9.05 months, p=0.001), and ctDNA +was independently associated with a shorter PFS (HR, 95% CI: 2.67, 1.2-5.96; p=0.016) by multivariable analyses. Patients with a higher mutant-allele tumor heterogeneity (MATH) score (≥6.316) or a higher ctDNA fraction (ctDNA%≥0.05) had a significantly shorter PFS than patients with a lower MATH score (5.67 months vs.11.27 months, p=0.007) and patients with a lower ctDNA% (5.45 months vs. 12.17 months, p<0.001), respectively. Positive correlations with treatment response were observed for MATH score (R=0.24, p=0.014) and ctDNA% (R=0.3, p=0.002), but not the CEA, CA125, or CA153. Moreover, patients who remained ctDNA +during dynamic monitoring tended to have a shorter PFS than those who did not (3.90 months vs. 6.10 months, p=0.135).

Conclusions

ctDNA profiling provides insight into the mutational landscape of mTNBC and may reliably predict the prognosis and treatment response of mTNBC patients.

Funding

This work was supported by the National Natural Science Foundation of China (Grant No. 81902713), Natural Science Foundation of Shandong Province (Grant No. ZR2019LZL018), Breast Disease Research Fund of Shandong Provincial Medical Association (Grant No. YXH2020ZX066), the Start-up Fund of Shandong Cancer Hospital (Grant No. 2020-PYB10), Beijing Science and Technology Innovation Fund (Grant No. KC2021-ZZ-0010-1).

Gene amplification-driven RNA methyltransferase KIAA1429 promotes tumorigenesis by regulating BTG2 via m6A-YTHDF2-dependent in lung adenocarcinoma

Background

Epigenetic alterations have been shown to contribute immensely to human carcinogenesis. Dynamic and reversible N6‐methyladenosine (m6A) RNA modification regulates gene expression and cell fate. However, the reasons for activation of KIAA1429 (also known as VIRMA, an RNA methyltransferase) and its underlying mechanism in lung adenocarcinoma (LUAD) remain largely unexplored. In this study, we aimed to clarify the oncogenic role of KIAA1429 in the tumorigenesis of LUAD.

Methods

Whole‐genome sequencing and transcriptome sequencing of LUAD data were used to analyze the gene amplification of RNA methyltransferase. The in vitro and in vivo functions of KIAA1429 were investigated. Transcriptome sequencing, methylated RNA immunoprecipitation sequencing (MeRIP‐seq), m6A dot blot assays and RNA immunoprecipitation (RIP) were performed to confirm the modified gene mediated by KIAA1429. RNA stability assays were used to detect the half‐life of the target gene.

Results

Copy number amplification drove higher expression of KIAA1429 in LUAD, which was correlated with poor overall survival. Manipulating the expression of KIAA1429 could regulate the proliferation and metastasis of LUAD. Mechanistically, the target genes of KIAA1429‐mediated m6A modification were confirmed by transcriptome sequencing and MeRIP‐seq assays. We also revealed that KIAA1429 could regulate BTG2 expression in an m6A‐dependent manner. Knockdown of KIAA1429 significantly decreased the m6A levels of BTG2 mRNA, leading to enhanced YTH m6A RNA binding protein 2 (YTHDF2, the m6A “reader”)‐dependent BTG2 mRNA stability and promoted the expression of BTG2; thus, participating in the tumorigenesis of LUAD.

Conclusions

Our data revealed the activation mechanism and important role of KIAA1429 in LUAD tumorigenesis, which may provide a novel view on the targeted molecular therapy of LUAD.

BTG2 as a tumor target for the treatment of luminal A breast cancer

As one of the most common breast cancer subtypes, luminal A breast cancer is sensitive to endocrine-based therapy and insensitive to chemotherapy. Patients with luminal A subtype of breast cancer have a relatively good prognosis compared with that of patients with other subtypes of breast cancer. However, with the increased incidence in endocrine resistance and severe side effects, simple endocrine therapy has become unsuitable for the treatment of luminal A breast cancer. Therefore, identifying novel therapeutic targets for luminal A breast cancer may accelerate the development of an effective therapeutic strategy. The bioinformatical analysis of the current study, which included KEGG and GO analyses of the GSE20437 dataset containing 24 healthy and 18 breast cancer tissue samples, identified key target genes associated with breast cancer. Moreover, survival analysis results revealed that a low expression of BTG2 was significantly associated with the low survival rate of patients with breast cancer, indicated that B-cell translocation gene 2 (BTG2) may be a potential target in breast cancer. However, BTG2 may be cancer type-dependent, as overexpression of BTG2 has been demonstrated to suppress the proliferation of pancreatic and lung cancer cells, but promote the proliferation of bladder cancer cells. Since the association between BTG2 and luminal A-subtype breast cancer remains unclear, it is important to understand the biological function of BTG2 in luminal A breast cancer. Based on the expression levels of estrogen receptor, progesterone receptor and human epidermal growth factor receptor, MCF-7 cells were selected in the present study as a luminal A breast cancer cell type. MTT, Transwell invasion and wound healing assays revealed that overexpression of BTG2 suppressed the levels of MCF-7 cell proliferation, migration and invasion. In addition, the downregulation of BTG2 at the mRNA and protein level was also confirmed in luminal A breast tumor tissue, which was consistent with the results in vitro. These results indicated that BTG2 may act as an effective target for the treatment of luminal A breast cancer.

MicroRNA miR-92a-3p regulates breast cancer cell proliferation and metastasis via regulating B-cell translocation gene 2 (BTG2)

MicroRNAs (miRNAs) dysregulation contributes to tumorigenesis, and it is reported that abnormal miR-92a-3p expression participates in multiple cancers’ occurrence and progression. This study focuses on miR-92a-3p’s functions and regulatory mechanism in breast cancer (BC). The current study proved miR-92a-3p expression was enhanced in BC tissues and cells, and its high expression was related to increased TNM stage and larger tumor size of BC patients. Functionally, transfection of miR-92a-3p mimics facilitated BC cell proliferation and metastasis, yet transfection of miR-92a-3p inhibitors functioned oppositely. In addition, BTG2 was verified as a direct miR-92a-3p target in BC cells. This research indicated that miR-92a-3p facilitates BC cell proliferation and metastasis through repressing BTG2 expression.

microRNAs Promoting Growth of Gastric Cancer Xenografts and Correlation to Clinical Prognosis

The annual death toll for gastric cancer is in the range of 700,000 worldwide. Even in patients with early-stage gastric cancer recurrence within five years has been observed after surgical resection and following chemotherapy with therapy-resistant features. Therefore, the identification of new targets and treatment modalities for gastric cancer is of paramount importance. In this review we focus on the role of microRNAs with documented efficacy in preclinical xenograft models with respect to growth of human gastric cancer cells. We have identified 31 miRs (-10b, -19a, -19b, -20a, -23a/b, -25, -27a-3p, -92a, -93, -100, -106a, -130a, -135a, -135b-5p, -151-5p, -187, -199-3p, -215, -221-3p, -224, -340a, -382, -421, -425, -487a, -493, -532-3p, -575, -589, -664a-3p) covering 26 different targets which promote growth of gastric cancer cells in vitro and in vivo as xenografts. Five miRs (miRs -10b, 151-5p, -187, 532-3p and -589) additionally have an impact on metastasis. Thirteen of the identified miRs (-19b, -20a/b, -25, -92a, -106a, -135a, -187, -221-3p, -340a, -421, -493, -575 and -589) have clinical impact on worse prognosis in patients.

Platelet microparticles-derived miR-25-3p promotes the hepatocyte proliferation and cell autophagy via reducing B-cell translocation gene 2

Platelets are critical regulators of liver regeneration, but the mechanisms are still not fully understood. Platelets have been shown to contain a wide variety of microRNAs (miRNAs) and play an important role in many diseases. However, the mechanism that how the platelet microparticles (PMPs)-derived miRNA regulate the hepatocyte proliferation is not very clear. In this study, we have successfully isolated and identified PMPs. We also found that PMPs, which could be well integrated into the HHL-5 cells, could upregulate the level of miR-25-3p in HHL-5 cells. Meanwhile, we found that PMPs-derived miR-25-3p promoted HHL-5 cells proliferation by accelerating cells into the S phase, and enhanced the autophagy by increasing the LC3II expression and reducing the P62 expression. Then, we proved that the miR-25-3p could target the B-cell translocation gene 2 (BTG2) and downregulate the expression levels of the BTG2 gene in HHL-5 cells. In addition, the overexpression of BTG2 significantly inhibited the proliferation and autophagy abilities of HHL-5 cells, while cotransfected miR-25-3p mimics or PMPs could partially rescue HHL-5 cells proliferation and autophagy. Furthermore, we proved that PMPs accelerated hepatocyte proliferation by regulating autophagy pathways. Therefore, PMPs-derived miR-25-3p promoted HHL-5 cell proliferation and autophagy by targeting BTG2, which may be a new therapeutic method for liver regeneration.

MicroRNA-27a-3p Reverses Adriamycin Resistance by Targeting BTG2 and Activating PI3K/Akt Pathway in Breast Cancer Cells

Aim

This study aimed to explore the regulative mechanisms of miR-27a-3p in chemo-resistance of breast cancer cells.

Materials and Methods

qRT-PCR was employed to determine miR-27a-3p expression in two breast cancer cell lines, MCF-7 and MCF-7/adriamycin-resistant cell line (MCF-7/ADR). The two cell lines were treated with miR-27a-3p mimics or inhibitors or corresponding negative control (NC), respectively. The changes were investigated by qRT-PCR, CCK-8 assay, Western blot (WB), colony formation assay, and flow cytometry assay. Moreover, luciferase reporter assay was analyzed to verify the downstream target gene of miR-27a-3p. Further investigation in the correlation between miR-27a-3p and BTG2 was launched by WB, flow cytometry assay, and CCK-8 assay. The expression of Akt and p-Akt was detected by WB.

Key Findings

Significantly higher miR-27a-3p expression was confirmed in MCF-7/ADR as compared with sensitive cell line MCF-7 (P<0.05). The down-regulation of miR-27a-3p in MCF-7/ADR enhanced the sensitivity of cancer cells to adriamycin treatment, decreased multidrug resistance gene 1/P-glycoprotein (MDR1/P-gp) expression, enhanced the apoptosis-related proteins expression, increased adriamycin-induced apoptosis, and inhibited cell proliferation as compared to NC groups (P<0.05). The up-regulation of miR-27a-3p in MCF-7 showed the opposite results. BTG2 is identified as a direct target of miR-27a-3p and its down-regulation reversed ADR-resistance. BTG2 treatment exhibited inhibitory effect on PI3K/Akt pathway in MCF-7/ADR cells.

Significance

miR-27a-3p might be associated with resistance of breast cancer cells to adriamycin treatments, modulating cell proliferation and apoptosis by targeting BTG2 and promoting the PI3K/Akt pathway in breast cancer cells. miR-27a-3p/BTG2 axis might be a potential therapeutic target for clinical BC resistance.

Pancreatic cancer cell-derived exosomal microRNA-27a promotes angiogenesis of human microvascular endothelial cells in pancreatic cancer via BTG2

Pancreatic cancer (PC) remains a primary cause of cancer-related deaths worldwide. Existing literature has highlighted the oncogenic role of microRNA-27a (miR-27a) in multiple cancers. Hence, the current study aimed to clarify the potential therapeutic role of PC cell-derived exosomal miR-27a in human microvascular endothelial cell (HMVEC) angiogenesis in PC. Initially, differentially expressed genes (DEGs) and miRs related to PC were identified by microarray analysis. Microarray analysis provided data predicting the interaction between miR-27a and BTG2 in PC, which was further verified by the elevation or depletion of miR-27a. Next, the expression of miR-27a and BTG2 in the PC tissues was quantified. HMVECs were exposed to exosomes derived from PC cell line PANC-1 to investigate the effects associated with PC cell-derived exosomes carrying miR-27a on HMVEC proliferation, invasion and angiogenesis. Finally, the effect of miR-27a on tumorigenesis and microvessel density (MVD) was analysed after xenograft tumour inoculation in nude mice. Our results revealed that miR-27a was highly expressed, while BTG2 was poorly expressed in both PC tissues and cell lines. miR-27a targeted BTG2. Moreover, miR-27a silencing inhibited PC cell proliferation and invasion, and promoted apoptosis through the elevation of BTG2. The in vitro assays revealed that PC cell-derived exosomes carrying miR-27a stimulated HMVEC proliferation, invasion and angiogenesis, while this effect was reversed in the HMVECs cultured with medium containing GW4869-treated PANC-1 cells. Furthermore, in vivo experiment revealed that miR-27a knockdown suppressed tumorigenesis and MVD. Taken together, cell-derived exosomes carrying miR-27a promotes HMVEC angiogenesis via BTG2 in PC.

Transcriptomic Pattern of Genes Regulating Protein Response and Status of Mitochondrial Activity Are Related to Oocyte Maturational Competence-A Transcriptomic Study

This paper aims to identify and describe new genetic markers involved in the processes of protein expression and modification reflected in the change of mitochondrial activity before and after in vitro maturation of the oocyte. Porcine oocytes collected from the ovaries of slaughtered landrace gilts were subjected to the process of in vitro maturation. Transcriptomic changes in the expression profile of oocyte genes involved in response to hypoxia, the transmembrane protein receptor serine threonine kinase signaling pathway, the “transforming growth factor β receptor signaling pathway”, “response to protein stimulus”, and “response to organic substance” were investigated using microarrays. The expression values of these genes in oocytes was analyzed before (immature) and after (mature) in vitro maturation, with significant differences found. All the significantly altered genes showed downregulation after the maturation process. The most changed genes from these gene ontologies, FOS, ID2, VEGFA, BTG2, CYR61, ESR1, AR, TACR3, CCND2, CHRDL1, were chosen to be further validated, described and related to the literature. Additionally, the mitochondrial activity of the analyzed oocytes was measured using specific dyes. We found that the mitochondrial activity was higher before the maturation process. The analysis of these results and the available literature provides a novel insight on the processes that occur during in vitro oocyte maturation. While this knowledge may prove to be useful in further research of the procedures commonly associated with in vitro fertilization procedures, it serves mostly as a basic reference for further proteomic, in vivo, and clinical studies that are necessary to translate it into practical applications.

MiR-6875-3p promotes the proliferation, invasion and metastasis of hepatocellular carcinoma via BTG2/FAK/Akt pathway

Background

Increasing evidence supports the association of microRNA with tumor occurrence and development. However, the expression of miR-6875-3p and its role in cell proliferation, invasion and metastasis in hepatocellular carcinoma (HCC) remains elusive.

Methods

The expression of miR-6875-3p and BTG2 in HCC tissues and cell lines was detected by using in situ hybridization, immunohistochemistry and qRT-PCR, respectively. A western blot assay, qRT-PCR and Luciferase reporter assay were employed to study the interaction between miR-6875-3p and BTG2. Cell proliferation invasion and metastasis were measured by MTT, transwell and matrigel analyses in vitro. In vivo, tumorigenicity and metastasis assays were performed in nude mice.

Results

We found that miR-6875-3p were elevated expressed in HCC tissues and cell lines, and negatively correlated with BTG2 expression, while positively correlated with tumor staging, size, degree of differentiation, and vascular invasion of HCC. Moreover, in vitro and in vivo assays showed that miR-6875-3p regulates EMT and improve the proliferation, metastasis and stem cell-like properties of HCC cells. BTG2 was identified as a direct and functional target of miR-6875-3p via the 3’-UTR of BTG2. We also confirmed that miR-6875-3p plays its biological functions via the BTG2/FAK/Akt pathway.

Conclusion

Our study provides evidence that high expression of miR-6875-3p can promote tumorigenesis of HCC in vitro and in vivo, so as to function as a novel oncogene in HCC. In mechanism, we found that miR-6875-3p plays its biological functions via the BTG2/FAK/Akt pathway.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-1020-z) contains supplementary material, which is available to authorized users.

Immunohistochemical Study of NR2C2, BTG2, TBX19, and CDK2 Expression in 31 Paired Primary/Recurrent Nonfunctioning Pituitary Adenomas

This study investigated potential markers for predicting nonfunctioning pituitary adenoma (NFPA) invasion and recurrence by high-throughput tissue microarray analyses. We retrospectively studied two groups of patients: 60 nonrecurrent NFPA cases that included noninvasion and invasion subtypes and 43 recurrent cases that included primary NFPA. A total of 31 paired patient samples were evaluated (12 patients with one surgery and 31 who had undergone two operations, with both tumors analyzed). Expressions of nuclear receptor subfamily 2 group C member 2 (NR2C2), B cell translocation gene 2, T-box-19 (TBX19), and cyclin-dependent kinase 2 (CDK2) in surgically resected specimens were assessed by immunohistochemistry. The relationships between marker expression and clinical characteristics including age, sex, tumor volume, and follow-up time were analyzed. Tumor volume and invasion as well as follow-up time were significantly associated with invasion and recurrence (P < 0.01). Of the 60 nonrecurrent samples, 15/41 and 13/19 showed high NR2C2 expression in the noninvasion and invasion groups, respectively (χ ² =5.287, P = 0.021). NR2C2 was also overexpressed in 43 primary recurrent cases (χ ² =5.433, P = 0.02), whereas CDK2 (χ ² = 11.242, P = 0.001) and TBX19 (χ ² = 4.875, P = 0.027) were downregulated. In the 31 paired samples, NR2C2 was more highly expressed in the recurrent as compared to the primary tumor. High NR2C2 expression was associated with NFPA invasion, recurrence, and progression, while TBX19 and CDK2 were associated with NFPA recurrence.

A multi-omic study reveals BTG2 as a reliable prognostic marker for early-stage non-small cell lung cancer

B-cell translocation gene 2 (BTG2) is a tumour suppressor protein known to be downregulated in several types of cancer. In this study, we investigated a potential role for BTG2 in early-stage non-small cell lung cancer (NSCLC) survival. We analysed BTG2 methylation data from 1230 early-stage NSCLC patients from five international cohorts, as well as gene expression data from 3038 lung cancer cases from multiple cohorts. Three CpG probes (cg01798157, cg06373167, cg23371584) that detected BTG2 hypermethylation in tumour tissues were associated with lower overall survival. The prognostic model based on methylation could distinguish patient survival in the four cohorts [hazard ratio (HR) range, 1.51-2.21] and the independent validation set (HR = 1.85). In the expression analysis, BTG2 expression was positively correlated with survival in each cohort (HR range, 0.28-0.68), which we confirmed with meta-analysis (HR = 0.61, 95% CI 0.54-0.68). The three CpG probes were all negatively correlated with BTG2 expression. Importantly, an integrative model of BTG2 methylation, expression and clinical information showed better predictive ability in the training set and validation set. In conclusion, the methylation and integrated prognostic signatures based on BTG2 are stable and reliable biomarkers for early-stage NSCLC. They may have new applications for appropriate clinical adjuvant trials and personalized treatments in the future.

MiR-27a-3p functions as an oncogene in gastric cancer by targeting BTG2

microRNA-27a (miR-27a) is frequently dysregulated in human carcinoma, including gastric cancer. The B-cell translocation gene 2 (BTG2) has been implicated in gastric carcinogenesis. However, till now, the link between miR-27a and BTG2 in gastric cancer has not been reported. Here, we found that two isoforms of mature miR-27a, miR-27a-5p and miR-27-3p, were both frequently overexpressed in gastric cancer tissues and cell lines, whereas the expression level of miR-27-3p in gastric cancer was significantly higher than that of miR-27a-5p. And overexpression of miR-27a-3p, but not miR-27a-5p, markedly promoted gastric cancer cell proliferation in vitro as well as tumor growth in vivo. Further experiments revealed that BTG2 was a direct and functional target of miR-27a-3p in gastric cancer and miR-27a-3p inhibition obviously up-regulated the expression of BTG2. In turn, overexpression of BTG2 triggered G1/S cell cycle arrest, induced subsequent apoptosis, and inhibited C-myc activation following Ras/MEK/ERK signaling pathway, which involved in the biological effects of miR-27a-3p/BTG2 axis on gastric carcinogenesis and cancer progression. Overall, these results suggested that the miR-27a-3p/BTG2 axis might represent a promising diagnostic biomarker for gastric cancer patients and could be a potential therapeutic target in the management of gastric cancer.

MiR-25-3p promotes the proliferation of triple negative breast cancer by targeting BTG2

Background

Triple-negative breast cancer (TNBC) is highly invasive and aggressive and lacks specific molecular targets to improve the prognosis. MiR-25-3p promotes proliferation of many tumors and its role and underlying mechanisms in TNBC remain to be well elucidated.

Methods

Differential expression of miR-25-3p in TNBC was measured with quantitative real-time PCR (qRT-PCR) in both TNBC tissues and cell lines and was validated in the Cancer Genome Atlas (TCGA) database. The effects of miR-25-3p on proliferation, apoptosis capacity of TNBC were evaluated using Cell counting kit-8 (CCK-8), colony formation assay and Annexin V-FITC/PI analyses. The tumor growth in vivo was observed in xenograft model. Luciferase reporter assay, qPCR and western blot were performed to validate a potential target of miR-25-3p in TNBC. Involvement of the AKT and MAPK pathways was investigated by western blot.

Results

MiR-25-3p was found to be upregulated in TNBC in tissues and cell lines. MiR-25-3p promoted TNBC cell proliferation in vitro and tumor growth in xenograft model, while suppression of miR-25-3p induced cell apoptosis. The luciferase reporter assay confirmed that B-cell translocation gene 2 (BTG2) might be a direct target of miR-25-3p, and its expression was negatively regulated by miR-25-3p. Moreover, inhibition of BTG2 expression accounted for the role of miR-25-3p in TNBC. Furthermore, BTG2 suppression might indirectly activate the AKT and ERK-MAPK signaling pathways to mediate the downstream effects of miR-25-3p.

Conclusions

This study demonstrates that miR-25-3p promotes proliferation by targeting tumor suppressor BTG2 and may identify new diagnostic and therapeutic targets in TNBC.

Electronic supplementary material

The online version of this article (10.1186/s12943-017-0754-0) contains supplementary material, which is available to authorized users.

Gamma Irradiation Upregulates B-cell Translocation Gene 2 to Attenuate Cell Proliferation of Lung Cancer Cells Through the JNK and NF-κB Pathways

Gamma ray can promote cancer cell apoptosis and cell cycle arrest. It is often used in the clinical treatment of tumors, including lung cancer. In this study, we aimed to explore the role of gamma ray treatment and its correlation with BTG2 in cell proliferation, apoptosis, and cell cycle arrest regulation in a lung cancer cell line. A549 cell viability, apoptosis rate, and cell cycle were investigated after gamma ray treatment. We then used siRNA for BTG2 to detect the effect of BTG2 knockdown on the progress of gamma ray-treated lung cancer cells. Finally, we investigated the signaling pathway by which gamma ray might regulate BTG2. We found that gamma ray inhibited A549 cell viability and promoted apoptosis and cell cycle arrest, while BTG2 knockdown could relieve the effect caused by gamma ray on A549 cells. Moreover, we confirmed that the effect of BTG2 partly depends on p53 expression and gamma ray-promoting BTG2 expression through the JNK/NF-κB signaling pathway. Our study assessed the possible mechanism of gamma ray in tumor treatment and also investigated the role of BTG2 in gamma ray therapy. All these findings might give a deep understanding of the effect of gamma ray on the progression of lung cancer involving BTG2.

Screening key genes and miRNAs in early-stage colon adenocarcinoma by RNA-sequencing

Colon adenocarcinoma is the third leading cause of cancer-related deaths across the world, developing novel and non-invasive diagnostic and prognostic biomarkers for the early-stage colon adenocarcinoma at molecular level is essential. In our study, RNA-sequencing was performed to identify the differentially expressed genes and miRNAs (DEmiRNAs) in early-stage colon adenocarcinoma compared to tissues of precancerous lesions, colonic intraepithelial neoplasia. The DEmiRNA-target interaction network was constructed and functional annotation of targets of DEmiRNAs was performed. The Cancer Genome Atlas was used to verify the expression of selected differentially expressed genes. The receiver operating characteristic analyses of selected differentially expressed genes was performed. In total, 865 differentially expressed genes, 26 DEmiRNAs, and 329 DEmiRNA-target pairs were obtained. Based on the early-stage colon adenocarcinoma network, miR-548c-5p, miR-548i, and miR-548am-5p were the top three DEmiRNAs that covered most differentially expressed genes. NTRK2, DTNA, and BTG2 were the top three differentially expressed genes regulated by most DEmiRNAs. Cancer and colorectal cancer pathways were two significantly enriched pathways in early-stage colon adenocarcinoma. The common differentially expressed genes in both the pathways were AXIN2, Smad2, Smad4, PIK3R1, and BCL2. The expression levels of eight differentially expressed genes (NTRK2, DTNA, BTG2, COL11A1, Smad2, Smad4, PIK3R1, and BCL2) in The Cancer Genome Atlas database were compatible with our RNA-sequencing. All these eight differentially expressed genes and AXIN2 had the potential diagnosis value for Colon adenocarcinoma. In conclusion, a total of ten differentially expressed genes (NTRK2, DTNA, BTG2, COLCA1, COL11A1, AXIN2, Smad2, Smad4, PIK3R1, and BCL2) and four DEmiRNAs (miR-548c-5p, miR-548i, mir-424-5p, and miR-548am-5p) may be involved in the pathogenesis of early-stage colon adenocarcinoma which may make a contribution for developing new diagnostic and therapeutic strategies for early-stage colon adenocarcinoma.

Aquaporin-3 deletion in mice results in renal collecting duct abnormalities and worsens ischemia-reperfusion injury

Aquaporin-3 (AQP3), a transporter of water, glycerol and H₂O₂, is expressed in basolateral membranes of principal cells in kidney collecting duct. Here, we report that AQP3 deletion in mice affects renal function and modulates renal injury. We found collecting duct hyperplasia and cell swelling in kidneys of adult AQP3 null mice. After mild renal ischemia-reperfusion (IR), AQP3 null mice had significantly greater blood urea nitrogen (57mg/dl) and creatinine (136μM) than wild-type mice (35mg/dl and 48μM, respectively), and showed renal morphological changes, including tubular dilatation, erythrocyte diapedesis and collecting duct incompletion. MPO, MDA and SOD following IR in AQP3 null mice were significantly different from that in wild-type mice (1.7U/g vs 0.8U/g, 3.9μM/g vs 2.4μM/g, 6.4U/mg vs 11U/mg, respectively). Following IR, AQP3 deletion inhibited activation of mitogen-activated protein kinase (MAPK) signaling and produced an increase in the ratios of Bax/Bcl-2, cleaved caspase-3/caspase-3 and p-p53/p53. Studies in transfected MDCK cells showed that AQP3 expression attenuated reduced cell viability following hypoxia-reoxygenation, with reduced apoptosis and increased MAPK signaling. Our results support a novel role for AQP3 in modulating renal injury and suggest the mechanisms involved in protection against hypoxic injury.

Tumor suppressor BTG1 promotes PRMT1-mediated ATF4 function in response to cellular stress

Cancer cells are frequently exposed to physiological stress conditions such as hypoxia and nutrient limitation. Escape from stress-induced apoptosis is one of the mechanisms used by malignant cells to survive unfavorable conditions. B-cell Translocation Gene 1 (BTG1) is a tumor suppressor that is frequently deleted in acute lymphoblastic leukemia and recurrently mutated in diffuse large B cell lymphoma. Moreover, low BTG1 expression levels have been linked to poor outcome in several solid tumors. How loss of BTG1 function contributes to tumor progression is not well understood. Here, using Btg1 knockout mice, we demonstrate that loss of Btg1 provides a survival advantage to primary mouse embryonic fibroblasts (MEFs) under stress conditions. This pro-survival effect involves regulation of Activating Transcription Factor 4 (ATF4), a key mediator of cellular stress responses. We show that BTG1 interacts with ATF4 and positively modulates its activity by recruiting the protein arginine methyl transferase PRMT1 to methylate ATF4 on arginine residue 239. We further extend these findings to B-cell progenitors, by showing that loss of Btg1 expression enhances stress adaptation of mouse bone marrow-derived B cell progenitors. In conclusion, we have identified the BTG1/PRMT1 complex as a new modifier of ATF4 mediated stress responses.

MicroRNA‑21 regulates the expression of BTG2 in HepG2 liver cancer cells

B-cell translocation gene 2 (BTG2) is a tumor suppressor gene, which belongs to the anti-proliferation gene family. Our previous study demonstrated that microRNA (miR)-21 and the expression of BTG2 were negatively correlated during hepatocarcinogenesis. The aim of the present study was to investigate the effects of miR-21 on the growth and progression of liver cancer cells, and to determine the underlying mechanism. A luciferase reporter assay was used to demonstrate that the BTG2 gene was a direct target of miR-21. In addition, the effects of miR-21 on cell growth and gene expression in HepG2 human hepatocellular carcinoma (HCC) cells were analyzed using reverse transcription-quantitative polymerase chain reaction, western blotting, an MTT assay, flow cytometry, a Transwell invasion assay and a wound healing assay. The expression levels of miR-21 in the HepG2 cells were significantly higher, compared with those in L02 normal liver cells. The expression levels of BTG2 in liver cancer cell lines (HepG2 and Huh7) were significantly lower, compared with that in the L02 cells. These results suggested that BTG2 was the direct target gene of miR-21. The protein expression levels of BTG2 were inhibited by high expression levels of miR-21, and increased by inhibition of the expression of miR-21 in the HepG2 cells. Inhibition of miR-21 reduced cell proliferation and invasion, and increased the rate of apoptosis in the HepG2 cells. These results indicated that miR-21 regulates cell proliferation, invasion, migration and apoptosis in HepG2 cells, which may be associated with its effects on the expression of BTG2. The results of the present study may provide a basis for targeting the miR-21/BTG2 interaction for the treatment of HCC.

MiR-21 Protected Cardiomyocytes against Doxorubicin-Induced Apoptosis by Targeting BTG2

Doxorubicin (DOX) is an anthracycline drug with a wide spectrum of antineoplastic activities. However, it causes cardiac cytotoxicity, and this limits its clinical applications. MicroRNA-21 (miR-21) plays a vital role in regulating cell proliferation and apoptosis. While miR-21 is preferentially expressed in adult cardiomyocytes and involved in cardiac development and heart disease, little is known regarding its biological functions in responding to DOX-induced cardiac cytotoxicity. In this study, the effects of DOX on mouse cardiac function and the expression of miR-21 were examined in both mouse heart tissues and rat H9C2 cardiomyocytes. The results showed that the cardiac functions were more aggravated in chronic DOX injury mice compared with acute DOX-injury mice; DOX treatment significantly increased miR-21 expression in both mouse heart tissue and H9C2 cells. Over-expression of miR-21 attenuated DOX-induced apoptosis in cardiamyocytes whereas knocking down its expression increased DOX-induced apoptosis. These gain- and loss- of function experiments showed that B cell translocation gene 2 (BTG2) was a target of miR-21. The expression of BTG2 was significantly decreased both in myocardium and H9C2 cells treated with DOX. The present study has revealed that miR-21 protects mouse myocardium and H9C2 cells against DOX-induced cardiotoxicity probably by targeting BTG2.

Transcriptome analysis in prenatal IGF1-deficient mice identifies molecular pathways and target genes involved in distal lung differentiation

Background

Insulin-like Growth Factor 1 (IGF1) is a multifunctional regulator of somatic growth and development throughout evolution. IGF1 signaling through IGF type 1 receptor (IGF1R) controls cell proliferation, survival and differentiation in multiple cell types. IGF1 deficiency in mice disrupts lung morphogenesis, causing altered prenatal pulmonary alveologenesis. Nevertheless, little is known about the cellular and molecular basis of IGF1 activity during lung development.

Methods/Principal Findings

Prenatal Igf1^−/− mutant mice with a C57Bl/6J genetic background displayed severe disproportional lung hypoplasia, leading to lethal neonatal respiratory distress. Immuno-histological analysis of their lungs showed a thickened mesenchyme, alterations in extracellular matrix deposition, thinner smooth muscles and dilated blood vessels, which indicated immature and delayed distal pulmonary organogenesis. Transcriptomic analysis of Igf1^−/− E18.5 lungs using RNA microarrays identified deregulated genes related to vascularization, morphogenesis and cellular growth, and to MAP-kinase, Wnt and cell-adhesion pathways. Up-regulation of immunity-related genes was verified by an increase in inflammatory markers. Increased expression of Nfib and reduced expression of Klf2, Egr1 and Ctgf regulatory proteins as well as activation of ERK2 MAP-kinase were corroborated by Western blot. Among IGF-system genes only IGFBP2 revealed a reduction in mRNA expression in mutant lungs. Immuno-staining patterns for IGF1R and IGF2, similar in both genotypes, correlated to alterations found in specific cell compartments of Igf1^−/− lungs. IGF1 addition to Igf1^−/− embryonic lungs cultured ex vivo increased airway septa remodeling and distal epithelium maturation, processes accompanied by up-regulation of Nfib and Klf2 transcription factors and Cyr61 matricellular protein.

Conclusions/Significance

We demonstrated the functional tissue specific implication of IGF1 on fetal lung development in mice. Results revealed novel target genes and gene networks mediators of IGF1 action on pulmonary cellular proliferation, differentiation, adhesion and immunity, and on vascular and distal epithelium maturation during prenatal lung development.

A high-throughput screen identifies miRNA inhibitors regulating lung cancer cell survival and response to paclitaxel

microRNAs (miRNAs) are small RNAs endogenously expressed in multiple organisms that regulate gene expression largely by decreasing levels of target messenger RNAs (mRNAs). Over the past few years, numerous studies have demonstrated critical roles for miRNAs in the pathogenesis of many cancers, including lung cancer. Cellular miRNA levels can be easily manipulated, showing the promise of developing miRNA-targeted oligos as next-generation therapeutic agents. In a comprehensive effort to identify novel miRNA-based therapeutic agents for lung cancer treatment, we combined a high-throughput screening platform with a library of chemically synthesized miRNA inhibitors to systematically identify miRNA inhibitors that reduce lung cancer cell survival and those that sensitize cells to paclitaxel. By screening three lung cancer cell lines with different genetic backgrounds, we identified miRNA inhibitors that potentially have a universal cytotoxic effect on lung cancer cells and miRNA inhibitors that sensitize cells to paclitaxel treatment, suggesting the potential of developing these miRNA inhibitors as therapeutic agents for lung cancer. We then focused on characterizing the inhibitors of three miRNAs (miR-133a/b, miR-361-3p, and miR-346) that have the most potent effect on cell survival. We demonstrated that two of the miRNA inhibitors (miR-133a/b and miR-361-3p) decrease cell survival by activating caspase-3/7-dependent apoptotic pathways and inducing cell cycle arrest in S phase. Future studies are certainly needed to define the mechanisms by which the identified miRNA inhibitors regulate cell survival and drug response, and to explore the potential of translating the current findings into clinical applications.