[miRNA-191 promotes proliferation, migration and invasion of prostate cancer by targeting PLCD1].

Objective: To investigate the effects of miRNA-191 on the proliferation, migration and invasion of prostate cancer, and to explore its mechanism. Methods: The expression levels of miRNA-191 in four human prostate cancer cell lines (PC-3, DU-145, LNCa P, 22RU1) and human normal prostate cell line RWPE-2 were detected, and prostate cancer cell line PC-3 was selected as the experimental object. PC-3 cells were divided into three groups: blank control group (no transfection), miRNA-191 NC group (PC-3 cells transfected with Inhibitor NC) and miRNA-191 Inhibitor group (PC-3 cells transfected with miRNA-191 Inhibitor), and each group was provided with three multiple pores. The expression levels of miRNA-191 and PLCD1 were detected by RT-PCR. The cell proliferation was detected by CCK8 assay. Scratch test and invasive test were used to detect cell migration and invasive ability. Through Targetscan target gene prediction website, PLCD1 was screened as the target protein of miRNA-191, and verified by double luciferase target experiment.Western blot assay was used to detect the expression of PLCD1 in cells of each group. Results: Compared with RWPE-2 cells, the expression level of miRNA-191 in human prostate cancer cells was significantly higher (P ＜0.05), and the expression level of miRNA191 in PC-3 was significantly higher than that in other three cell lines (P＜0.05). After inhibiting the expression of miRNA-191, the expression levels of PLCD1 was significantly higher while PC-3 cells' proliferation ability was inhibited, and their migration and invasion ability were significantly lower than those of blank control group and miRNA-191 NC group (P＜ 0.05). The results of double luciferase reporter gene assay showed that PLCD1 gene was a target gene of miRNA-191. Conclusion: miRNA-191 promote the proliferation, migration and invasion of prostate cancer PC-3 cells by targeting PLCD1.

Inactivation of SACE_3446, a TetR family transcriptional regulator, stimulates erythromycin production in Saccharopolyspora erythraea.

Erythromycin A is a widely used antibiotic produced by Saccharopolyspora erythraea; however, its biosynthetic cluster lacks a regulatory gene, limiting the yield enhancement via regulation engineering of S. erythraea. Herein, six TetR family transcriptional regulators (TFRs) belonging to three genomic context types were individually inactivated in S. erythraea A226, and one of them, SACE_3446, was proved to play a negative role in regulating erythromycin biosynthesis. EMSA and qRT-PCR analysis revealed that SACE_3446 covering intact N-terminal DNA binding domain specifically bound to the promoter regions of erythromycin biosynthetic gene eryAI, the resistant gene ermE and the adjacent gene SACE_3447 (encoding a long-chain fatty-acid CoA ligase), and repressed their transcription. Furthermore, we explored the interaction relationships of SACE_3446 and previously identified TFRs (SACE_3986 and SACE_7301) associated with erythromycin production. Given demonstrated relatively independent regulation mode of SACE_3446 and SACE_3986 in erythromycin biosynthesis, we individually and concomitantly inactivated them in an industrial S. erythraea WB. Compared with WB, the WBΔ3446 and WBΔ3446Δ3986 mutants respectively displayed 36% and 65% yield enhancement of erythromycin A, following significantly elevated transcription of eryAI and ermE. When cultured in a 5 L fermentor, erythromycin A of WBΔ3446 and WBΔ3446Δ3986 successively reached 4095 mg/L and 4670 mg/L with 23% and 41% production improvement relative to WB. The strategy reported here will be useful to improve antibiotics production in other industrial actinomycete.

Capturing the target genes of BldD in Saccharopolyspora erythraea using improved genomic SELEX method.

BldD (SACE_2077), a key developmental regulator in actinomycetes, is the first identified transcriptional factor in Saccharopolyspora erythraea positively regulating erythromycin production and morphological differentiation. Although the BldD of S. erythraea binds to the promoters of erythromycin biosynthetic genes, the interaction affinities are relatively low, implying the existence of its other target genes in S. erythraea. Through the genomic systematic evolution of ligands by exponential enrichment (SELEX) method that we herein improved, four DNA sequences of S. erythraea A226, corresponding to the promoter regions of SACE_0306 (beta-galactosidase), SACE_0811 (50S ribosomal protein L25), SACE_3410 (fumarylacetoacetate hydrolase), and SACE_6014 (aldehyde dehydrogenase), were captured with all three BldD concentrations of 0.5, 1, and 2 µM, while the previously identified intergenic regions of eryBIV-eryAI and ermE-eryCI plus the promoter region of SACE_7115, the amfC homolog for aerial mycelium formation, could be captured only when the BldD's concentration reached 2 µM. Electrophoretic mobility shift assay (EMSA) analysis indicated that BldD specifically bound to above seven DNA sequences, and quantitative real-time PCR (qRT-PCR) assay showed that the transcriptional levels of the abovementioned target genes decreased when bldD was disrupted in A226. Furthermore, SACE_7115 and SACE_0306 in A226 were individually inactivated, showing that SACE_7115 was predominantly involved in aerial mycelium formation, while SACE_0306 mainly controlled erythromycin production. This study provides valuable information for better understanding of the pleiotropic regulator BldD in S. erythraea, and the improved method may be useful for uncovering regulatory networks of other transcriptional factors.

Dissecting and engineering of the TetR family regulator SACE_7301 for enhanced erythromycin production in Saccharopolyspora erythraea.

BACKGROUND: Saccharopolyspora erythraea was extensively utilized for the industrial-scale production of erythromycin A (Er-A), a macrolide antibiotic commonly used in human medicine. Yet, S. erythraea lacks regulatory genes in the erythromycin biosynthetic gene (ery) cluster, hampering efforts to enhance Er-A production via the engineering of regulatory genes. RESULTS: By the chromosome gene inactivation technique based on homologous recombination with linearized DNA fragments, we have inactivated a number of candidate TetR family transcriptional regulators (TFRs) and identified one TFR (SACE_7301) positively controlling erythromycin biosynthesis in S. erythraea A226. qRT-PCR and EMSA analyses demonstrated that SACE_7301 activated the transcription of erythromycin biosynthetic gene eryAI and the resistance gene ermE by interacting with their promoter regions with low affinities, similar to BldD (SACE_2077) previously identified to regulate erythromycin biosynthesis and morphological differentiation. Therefore, we designed a strategy for overexpressing SACE_7301 with 1 to 3 extra copies under the control of PermE* in A226. Following up-regulated transcriptional expression of SACE_7301, eryAI and ermE, the SACE_7301-overexpressed strains all increased Er-A production over A226 proportional to the number of copies. Likewise, when SACE_7301 was overexpressed in an industrial S. erythraea WB strain, Er-A yields of the mutants WB/7301, WB/2×7301 and WB/3×7301 were respectively increased by 17%, 29% and 42% relative to that of WB. In a 5 L fermentor, Er-A accumulation increased to 4,230 mg/L with the highest-yield strain WB/3×7301, an approximately 27% production improvement over WB (3,322 mg/L). CONCLUSIONS: We have identified and characterized a TFR, SACE_7301, in S. erythraea that positively regulated erythromycin biosynthesis, and overexpression of SACE_7301 in wild-type and industrial S. erythraea strains enhanced Er-A yields. This study markedly improves our understanding of the unusual regulatory mechanism of erythromycin biosynthesis, and provides a novel strategy towards Er-A overproduction by engineering transcriptional regulators of S. erythraea.

Comparative study on cancer cell apoptosis between gastric and intestinal-type human gastric carcinoma.

Apoptosis of cancer cells between the gastric and intestinal-type human gastric carcinoma were compared in terms of the expression of oncogene MDM2 and CD68, the histological types, the infiltration depth, and lymph node metastasis. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) assay was employed to stain apoptotic cells. Histochemical method(AB-PAS) was applied to stain mucus that is neutral or acidic in nature. Immunohistochemical method (SABC) was used to detect expression of MDM2 and CD6. The results showed that the mean apoptosis index (AI) of total 48 cases was 8.60+/-2.60. AI in the 30 intestinal type cases was significantly higher than that in the 18 gastric type cases (t=4.67, P<0.01). In the 30 intestinal type cases, the spontaneous apoptosis index of MDM2 negative cases was significantly higher than that of the positive cases (t=7.16, P<0.01). And in the 18 gastric type cases, the same result was found. (t=11.39, P<0.01). The MDM2 positive ratio in gastric type cases was higher than that in intestinal type cases (chi2=4.68, P<0.05). There is no significant difference in AI between cases of lymph node metastasis and non-metastasis cases in intestinal type cases (t=0.26, P>0.05). But in the gastric type cases, a significant difference existed (t=5.87, P<0.01). A significant difference in lymph node metastasis ratio was found between the two gastric carcinoma types (chi2=4.48, P<0.05). The CD68 expression ratio in the 30 intestinal type cases was much lower than that in the 18 gastric type cases (t=4.29, P<0.01). AI of 25 MDM2-positive cases was much lower than that of the 23 MDM2-negative cases (t=7.80, P<0.01). CD68 positive ratio in the 25 MDM2-negative cases was much lower than that in the 23 negative cases. The difference was statistically significant (t=10.90, P<0.01). Except for few cells scattering within the cancer nest, most CD68 positive cells infiltrated in the interstitium around the cancer tissue. In the high-AI cases, CD68-positive cells increased. And the CD68-positive cells decreased in low-AI cases (r=0.96, P<0.01). Logistic regression analysis suggested that among the control variables, only AI was a statistically significant factor in the regression model (chi2=9.64, P<0.01). We concluded that (1) the spontaneous apoptosis index in gastric-type cases of gastric carcinoma was significantly lower than that in intestinal type cases; (2) AI in the two types was influenced by the expression of MDM2 and lymph node metastasis, but no visible connection was found between AI and the infiltration depth or histological types; (3) in the intestinal type cases, AI and the CD68-positive cells increased in MDM2-negative cases.

Expression of cell proliferating genes in patients with non-small cell lung cancer by immunohistochemistry and cDNA profiling.

Thymidine kinase 1 (TK1) is a key enzyme involved in the synthesis of DNA precursors and thus, cell proliferation-dependent. Antibodies against TK1 have provided attractive tools for cancer diagnosis. Expression of TK1 in 158 non-small cell lung cancer (NSCLC) patients with 59 adenocarcinoma (AC) and 99 squamous cell carcinoma (SCC) was determined by anti-TK1 monoclonal antibody (mAb) 1E3 (AC, n=50; SCC, n=70). Parallel tumor sections were stained for Ki-67 (MIB-1), and TK1 expression was also investigated with anti-TK1 chicken IgY Ab (AC, n=9; SCC, n=29; normal lung tissues, n=10). In one AC and one SCC patient, gene profiling was done by cDNA array. Using the mAb 1E3, a significantly higher TK1 labeling index (LI) of AC patients was found (68%) compared to the LI of Ki-67 (36%). This difference was due to a significantly higher TK1 LI of tumor stage II and grade 2. Although no difference in the LI of TK1 and Ki-67 of SCC patients was found (54 vs. 53%), significantly higher TK1 LI of SCC patients of tumor grade 1 was found. Using the anti-TK1 IgY Ab, a higher TK1 LI of AC patients (78%) and SCC patients (66%) was found compared to staining with mAb 1E3 (68 vs. 54%), but it was not significantly different. Samples stained only for TK1 represented mostly tumor stages I and II and grades 1 and 2 of both AC and SCC. AC patients whose samples stained only for Ki-67 were found to be in stage I and grade 1. cDNA profiling showed that the expression of BRCA1, cyclin B1 and cdc2p34 was higher in AC compared to SCC, while the expression of IGFBP-3 and EGFR was higher in SCC. TK1 is apparently a more reliable marker in AC patients than Ki-67. However, a combination of the two markers may help identify patients of different stages and grades more efficiently, and cyclin/kinase complexes and growth factors/receptors may be useful markers in distinguishing AC from SCC.

Cytosolic thymidine kinase is a specific histopathologic tumour marker for breast carcinomas.

Thymidine kinase 1 (TK1), an enzyme involved in the synthesis of precursors for DNA, and thus proliferation dependent, has been suggested as a good tumour marker. We have recently developed poly/monoclonal antibodies against TK1, which proved useful for diagnostics in both serum and immunohistochemistry of cancer patients. The anti-TK1 monoclonal antibodies (mAbs) 1D11 and 1E3 were characterized by Western blot, immunoprecipitation and flow cytometry. TK1 mAbs and Ki-67 mAb were then used for immunohistochemistry staining of tumour sections from 54 patients with ductal infiltrated breast carcinoma. Results showed the relative number of patients with positively stained tumours for TK1 (mAb 1D11) and for Ki-67 (mAb MIB-1) were 47 and 41%, respectively, significantly related (p=0.007). Combination of TK1 mAbs 1D11 and 1E3 increased this number to 56%, due to detection of a significantly higher number of patients with grade 2 tumours. Patients with stage II and grade 2 tumours showed significantly higher TK1 staining when compared to stage I and grade 1. Ki-67 staining was significantly higher in stage III and grade 3. The tumours only stained for TK1 represented higher stages and grades, while tumours staining only for Ki-67 were of lower stages and grades. Combining TK1 and Ki-67 increased the number of patients with positively stained tumours to 69%. In conclusion, TK1 is a reliable marker for identification of patients with grade 2 tumours. The highest number of patients with positively stained tumours were obtained when both TK1 and Ki-67 markers were used.

Production and characterisation of a novel chicken IgY antibody raised against C-terminal peptide from human thymidine kinase 1.

Egg yolk is a good source of highly specific antibodies against mammalian antigens because of the phylogenetic distance between birds and mammals. Chicken egg yolk immunoglobulins (IgY) were generated to a synthetic 31-amino acid peptide from the C-terminal of human HeLa thymidine kinase 1 (TK1) enzyme. The anti-TK1 IgY antibody was purified using affinity chromatography against the 31-amino acid peptide. The purified antibody inhibited the catalytic activity of the TK1 enzyme in the CEM TK1(+) cells and recognized the 25-kDa subunit and tetrameric form of TK1, which has a pI value of 8.3. No immunoreaction was observed in CEM TK1(-) cells. Western blot of the serum TK1 (S-TK1) also showed that only a single band was found in the serum of patients with malignancies. No band was seen in healthy serum. Furthermore, dot blots and enhanced chemiluminescence (ECL) detection of S-TK1 performed on sera of preoperative patients with gastric cancer (GC) (n=31) and healthy controls (n=62) showed that the levels of S-TK1 in the sera of cancer patients were significantly different (P<0.01). Using ECL dot blots, 0.1 pg of TK1 in 3 microl sera could be detected. Immunohistostaining of tissues in the 11 advanced-stage cancer patients (four breast carcinomas, three hepatocarcinomas and four thyroid carcinomas) indicated that a strong staining of TK1 enzyme was found in the cytoplasm of malignant cells. No staining or weak staining was seen in normal tissues. We suggest that screening for TK1 using anti-TK1 IgY may be potentially useful for serological and immunohistochemical detection of TK1 as an early prognosis and for monitoring patients undergoing treatment.

A comparative study: immunohistochemical detection of cytosolic thymidine kinase and proliferating cell nuclear antigen in breast cancer.

To explore the expression of cytosolic thymidine kinase 1 (TK1) as a cell proliferative marker in human breast cancers, immunohistochemistry was used to detect the expression of TK1 in 52 malignant breast lesions, 20 benign breast lesions, and 16 normal breast tissues. The results were compared to the expression of proliferating cell nuclear antigen (PCNA) in the same specimens. The TK1-labelling index (TK1-LI) and PCNA-labeling index (PCNA-LI) were significantly higher in malignant lesions than in nonmalignant lesions (p < 0.0001 and p < 0.0013, respectively). The TK1-LI (78.9%) in malignant lesions was higher compared to PCNA-LI (64.5%). No significant difference was found for TK1-LI and PCNA-LI between benign lesions and normal tissues. Concerning the tumor stages and the tumor grades, TK1-LI showed a significant correlation with the increased tumor stages (p = 0.023) and tumor grades (p = 0.009). However, PCNA-LI was neither significantly different in tumor stages (p = 0.062) nor in tumor grades (p = 0.073). We conclude that TK1 might be a more accurate marker than PCNA for estimation of cell proliferation and malignant potentials in breast carcinomas.