PRMT2ß, a C-terminal splice variant of PRMT2, inhibits the growth of breast cancer cells.

Our previous study reported several alternative splicing variants of arginine N-methyltransferase 2 (PRMT2), which lose different exons in the C-terminals of the wild-type PRMT2 gene. Particularly, due to frame-shifting, PRMT2ß encodes a novel amino acid sequence at the C-terminus of the protein, the function of which is not understood. In the present study, we determined the role of PRMT2ß in breast cancer cell proliferation, apoptosis and its effect on the Akt signaling pathway. Stable breast cancer MCF7 cell line with lentivirus-mediated PRMT2ß overexpression was obtained after selection by puromycin for 2 weeks. The effect of lentivirus-mediated PRMT2ß overexpression on breast cancer cellular oncogenic properties was evaluated by MTT, colony formation, cell cycle analysis and apoptosis assays in MCF7 cells. Luciferase activity assay and western blot analysis were performed to characterize the effects of PRMT2ß on cyclin D1 promoter activities and the Akt signaling pathway. Tissue microarray was performed to investigate the association of PRMT2ß with breast cancer progression. Lentivirus-mediated PRMT2ß overexpression suppressed the cell proliferation and colony formation of breast cancer MCF7 cells. PRMT2ß overexpression induced cell cycle arrest and apoptosis of MCF7 cells. Furthermore, PRMT2ß was revealed to suppress the transcription activity of the cyclin D1 promoter, and PRMT2ß was also found to inhibit cyclin D1 expression via the suppression of Akt/GSK-3ß signaling in breast cancer cells. Clinically, it was revealed that PRMT2ß expression was negatively correlated with human epidermal growth factor receptor 2 (HER2) (p=0.033) in breast tumors. Our results revealed that PRMT2ß, a novel splice variant of PRMT2, plays potential antitumor effect by suppressing cyclin D1 expression and inhibiting Akt signaling activity. This also opens a new avenue for treating breast cancer.

TGF-ß1 induces HMGA1 expression: The role of HMGA1 in thyroid cancer proliferation and invasion.

The role of transforming growth factor-ß1 (TGF-ß1) is complicated and plays a different role in the development of cancer. High mobility group A (HMGA1) participates in multiple cellular biology processes, and exerts important roles in the epithelial-mesenchymal transition (EMT). However, the correlation of TGF-ß1 and HMGA1 in cancer cells is not yet fully understood. In this study, we determined the effects of TGF-ß1 on HMGA1 expression in thyroid cancer cells and examined the role of HMGA1 in thyroid cancer progression. With real-time PCR and immunofluorescence staining, our study demonstrated that TGF-ß1 induced the expression of HMGA1 through phosphoinositide 3-kinase (PI3K) and the extracellular signal-related kinase (ERK) signaling in thyroid cancer cells. With luciferase reported assay, the HMGA1 promoter activity was activated by TGF-ß1 in the SW579 cells. Furthermore, lentivirus-mediated HMGA1 knockdown inhibits cellular oncogenic properties of thyroid cancer cells. Clinically, tissue microarray revealed that HMGA1 was expressed in thyroid carcinoma more than that in normal thyroid tissues (P<0.001); expression of HMGA1 and MMP-2 was identified to be positively correlated (P=0.017). The present study established the first link between HMGA1 and TGF-ß1 in the regulation of thyroid cancer proliferation and invasion, and provided evidence for the pivotal role of HMGA1 in the progression of thyroid cancer, indicating HMGA1 to be potential biological marker for the diagnosis of thyroid cancer.

The association between S100A13 and HMGA1 in the modulation of thyroid cancer proliferation and invasion.

BACKGROUND: S100A13 and high mobility group A (HMGA1) are known to play essential roles in the carcinogenesis and progression of cancer. However, the correlation between S100A13 and HMGA1 during cancer progression is not yet well understood. In this study, we determined the effects of S100A13 on HMGA1 expression in thyroid cancer cells and examined the role of HMGA1 in thyroid cancer progression. METHODS: Stable ectopic S100A13 expression TT cellular proliferation was evaluated by nude mice xenografts assays. The effect of lentivirus-mediated S100A13 knockdown on thyroid cancer cellular oncogenic properties were evaluated by MTT, colony formation assays and transwell assays in TPC1 and SW579 cells. The effect of siRNA-mediated HMGA1 knockdown on thyroid cancer cellular proliferation and invasion were evaluated by MTT, colony formation assays and transwell assays. The tissue microarray was performed to investigate the correlation between S100A13 and HMGA1 expression in tumor tissues. RESULTS: The ectopic expression of S100A13 could increase tumor growth in a TT cell xenograft mouse model. Moreover, lentivirus-mediated S100A13 knockdown led to the inhibition of cellular oncogenic properties in thyroid cancer cells, and HMGA1 was found to be involved in the effect of S100A13 on thyroid cancer growth and invasion. Furthermore, siRNA-mediated HMGA1 knockdown was proved to inhibit the growth of TPC1 cells and invasive abilities of SW579 cells. Clinically, it was revealed that both S100A13 and HMGA1 showed a higher expression levels in thyroid cancer cases compared with those in matched normal thyroid cases (P = 0.007 and P = 0.000); S100A13 and HMGA1 expressions were identified to be positively correlated (P = 0.004, R = 0.316) when analyzed regardless of thyroid cancer types. CONCLUSIONS: This is the first report for the association between HMGA1 and S100A13 expression in the modulation of thyroid cancer growth and invasion. Those results would provide an essential insight into the effect of S100A13 on carcinogenesis of thyroid tumor, rending S100A13 to be potential biological marker for the diagnosis of thyroid cancer.

The relationship between bone marrow characteristics and the clinical prognosis of antithyroid drug-induced agranulocytosis.

This study is aimed to explore the relationship between bone marrow characteristics and clinical prognosis of antithyroid drug (ATD) induced agranulocytosis. A retrospective study was conducted in the first affiliated hospital of the University of South China. A total of 33 hospitalized patients diagnosed with ATD-induced agranulocytosis were analyzed. The bone marrow characteristics were classified into two types. Type I was characterized by reduction or absence of granulocytic precursors and type II was recognized as hypercellular bone marrow with dysmaturity of granulocytic cells. Bone marrow of 20 cases (61%) were characterized with type I whereas 13 cases (39%) with type II. The median duration of neutrophil recovery and high-grade fever were 4.7 ± 1.0 days and 3.6 ± 2.5 days respectively for type II, compared to 8.0 ± 2.8 days and 8.6 ± 3.1 days for type I (p < 0.01 in both compared groups). However, there was no significant difference between the two types in terms of age, median duration of drug administration before the diagnosis of agranulocytosis, the amount of neutrophil count on admission and the total administration dose of granulocyte-colony stimulating factor (G-CSF) before bone marrow examination. Two cases of type I died of complications from infection. This study showed that the bone marrow characteristics of ATD-induced agranulocytosis could be classifed into two types. Also, the clinical prognosis was closely related to the bone marrow features. Type I is the dominant type which is usually associated with worse clinical prognosis compared to type II.

An involvement of SR-B1 mediated PI3K-Akt-eNOS signaling in HDL-induced cyclooxygenase 2 expression and prostacyclin production in endothelial cells.

It is well-known that sphingosine-1-phosphate (S1P), the phospholipid content of HDL, binding to S1P receptors can raise COX-2 expression and PGI(2) release through p38MAPK/CREB pathway. In the present study we assess the action of SR-B1 initiated PI3K-Akt-eNOS signaling in the regulation of COX-2 expression and PGI(2) production in response to HDL. We found that apoA1 could increase PGI(2) release and COX-2 expression in ECV 304 endothelial cells. Furthermore, SR-B1 was found to be involved in HDL induced up-regulation of COX-2 and PGI(2). Over-expressed SR-B1 did not significantly increase the expression of COX-2 and the PGI(2) levels, but knock-down of SR-B1 by siRNA could significantly attenuate COX-2 expression and PGI(2) release together with p38MAPK and CREB phosphorylation. Consistently, the declines of p-p38MAPK, p-CREB, COX-2 and PGI(2) were also observed after incubation with LY294002 (25µmol/L; PI3K special inhibitor) or L-NAME (50µmol/L; eNOS special inhibitor). In addition, we demonstrated the increases of PGI(2) release, COX-2 expression and p38MAPK phosphorylation, when nitric oxide level was raised through the incubation of L-arginine (10 or 20nmol/L) in endothelial cells. Taking together, our data support that SR-B1 mediated PI3K-Akt-eNOS signaling was involved in HDL-induced COX-2 expression and PGI(2) release in endothelial cells.

ATP citrate lyase inhibitors as novel cancer therapeutic agents.

ATP citrate lyase (ACL or ACLY) is an extra-mitochondrial enzyme widely distributed in various human and animal tissues. ACL links glucose and lipid metabolism by catalyzing the formation of acetyl-CoA and oxaloacetate from citrate produced by glycolysis in the presence of ATP and CoA. ACL is aberrantly expressed in many immortalized cells and tumors, such as breast, liver, colon, lung and prostate cancers, and is correlated reversely with tumor stage and differentiation, serving as a negative prognostic marker. ACL is an upstream enzyme of the long chain fatty acid synthesis, providing acetyl-CoA as an essential component of the fatty acid synthesis. Therefore, ACL is a key enzyme of cellular lipogenesis and potent target for cancer therapy. As a hypolipidemic strategy of metabolic syndrome and cancer treatment, many small chemicals targeting ACL have been designed and developed. This review article provides an update for the research and development of ACL inhibitors with a focus on their patent status, offering a new insight into their potential application.

Identification and characterization of novel spliced variants of PRMT2 in breast carcinoma.

Protein N-arginine methyltransferases (PRMTs) participate in a number of cellular processes, including cell growth, nuclear/cytoplasmic protein shuttling, differentiation, RNA splicing and post-transcriptional regulation. PRMT2 (also known as HRMT1L1) is clearly involved in lung function, the inflammatory response, apoptosis promotion, Wnt signaling and leptin signaling regulation through different mechanisms. In this study, we report the molecular and cell biological characterization of three novel PRMT2 splice variants isolated from breast cancer cells and referred to as PRMT2α, PRMT2ß and PRMT2γ. Compared with the wild-type PRMT2, these variants lack different motifs and therefore generate distinct C-terminal domains. Confocal microscopy scanning revealed a distinct intracellular localization of PRMT2 variants, suggesting that the alternatively spliced C-terminus of PRMT2 can directly influence its subcellular localization. Our findings reveal that these variants are capable of binding to estrogen receptor alpha (ERα) both in vitro and in vivo, and the N-terminal regions of these variants contribute to ERα-PRMT2 interactions. Furthermore, these variants were proved to be able to enhance ERα-mediated transactivation activity. Luciferase reporter assays showed that PRMT2s could modulate promoter activities of the ERα-targeted genes of Snail and E-cadherin. In addition, PRMT2 silencing could enhance 17ß-estradiol-induced proliferation by regulating E2F1 expression and E2F1-responsive genes in ERα-positive breast cancer cells. Real-time PCR and immunohistochemistry showed that overall PRMT2 expression was upregulated in breast cancer tissues and significantly associated with ERα positivity status both in breast cancer cell lines and breast cancer tissues. We speculate that PRMT2 and its splice variants may directly modulate ERα signaling and play a role in the progression of breast cancer.

Identification and expression analysis of a novel transcript of the human PRMT2 gene resulted from alternative polyadenylation in breast cancer.

The arginine N-methyltransferase 2 protein (PRMT2, also known as HRMT1L1) is thought to act as a coactivator of ERα. The present results show the occurrence of a novel transcript by alternative polyadenylation in the human PRMT2 gene. We demonstrated that the newly identified intron-retaining PRMT2L2 transcript is functionally intact, efficiently translated into protein in vivo. PRMT2 and PRMT2L2 mRNA expression profiles overlap with the distribution of ERα, with the strongest abundance in estrogen target tissues. Transient co-transfection assays demonstrated that PRMT2L2 enhance ERα-mediated transactivation activity of ERE-Luc in a ligand-dependent manner. Confocal microscopy scanning revealed a distinct intra-cellular localization of their fusion proteins, suggesting that the C-terminal region absent in PRMT2L2 is critical for the localization. Statistical analysis further showed that both PRMT2 and PRMT2L2 mRNAexpressions were up-regulated in breast cancer tissues, and significantly associated with ERα positivity status. Thus, post-transcriptional processing mechanism as alternative polyadenylation and splicing may play a crucial role in regulating human PRMT2 gene expression.

[Overexpressing exogenous S100A13 gene and its effect on proliferation of human thyroid cancer cell line TT].

BACKGROUND & OBJECTIVE: S100A13 is involved in tumor formation, and is highly expressed in human thyroid gland. This study was to investigate the effect of exogenous S100A13 overexpression on the proliferation of human thyroid cancer cell line TT. METHODS: The eukaryotic expression plasmid pCDNA3.1/NT-GFP-S100A13 and empty vector pCDNA3.1/NT-GFP were transfected into TT cells. The cells were selected by G418. The expression of green fluorescent protein (GFP) was observed under laser scanning microscope, and the expression of S100A13 mRNA and protein was detected by real-time reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. The effects of S100A13 on cell proliferation and cell cycle progression were measured by cell growth curve and flow cytometry. RESULTS: TT-S100A13-GFP and TT-GFP cells, which separately expressed S100A13 and pCDNA3.1/NT-GFP, were constructed successfully. TT-S100A13-GFP cells grew faster than TT-GFP and TT cells [(2.30+/-0.24) x 10(5) vs. (1.40+/-0.25) x 10(5) and (1.50+/-0.22) x 10(5) at the 7th day of cell culture, P<0.05]; both S phase proportion and G2/M phase proportion were significantly higher in TT-S100A13-GFP cells than in TT-GFP and TT cells [(6.47+/-0.14)% vs. (5.86+/-0.23)% and (5.99+/-0.28)% at S phase, P<0.05; (50.27+/-0.66)% vs. (39.39+/-0.23)% and (39.64+/-0.64)% at G2/M phase, P<0.05]. CONCLUSION: Exogenous S100A13 gene overexpression could accelerate cell proliferation, and promote cell cycle progression of TT cells from G0/G1 phase to S and G2/M phase.