Gene Dosage Is Not Responsible for the Upregulation of MRP1 Gene Expression in Adult Leukemia Patients

Effects of codon optimization, N-terminal truncation and gene dose on the heterologous expression of berberine bridge enzyme

Morphine, sanguinarine and chelerythrine are benzylisoquinoline alkaloids (BIAs), and these compounds possess strong biological activities. (S)-scoulerine is a commonly shared precursor of these compounds, and berberine bridge enzyme (BBE) is a key rate-limiting enzyme in the synthesis of (S)-scoulerine. We isolated the BBE gene from Macleaya cordata (McBBE) and used CEN.PK2-1C as a chassis strain. We compared the catalytic efficiency of five codon-optimized McBBE genes in Saccharomyces cerevisiae and finally obtained a yeast strain (YH03) that exhibited a 58-fold increase in yield (1.12 mg/L). Then, we truncated the N-terminus of McBBE by 8 and 22 amino acids and found that with the increase in the number of N-terminal truncated amino acids, the production of (S)-scoulerine gradually decreased. Additionally, we used CRISPR-Cas9 to integrate the McBBE gene at the delta site of the S. cerevisiae genome to achieve stable genetic inheritance and found that the yield of (S)-scoulerine was not significantly increased in the integrated strain. In conclusion, our work achieved high-efficiency expression of McBBE in S. cerevisiae, explored the influence of N-terminal truncation on the yield of (S)-scoulerine, and obtained a genetically stable S. cerevisiae strain with high McBBE expression. This study provides a reference for further complex metabolic engineering optimization and lays a foundation for the efficient biosynthesis of BIAs.

met1 DNA Methyltransferase Controls TERT Gene Expression: A New Insight to The Role of Telomerase in Development

Objective:

DNA methylation systems are essential for proper embryo development. Methylation defects lead to developmental abnormalities. Furthermore, changes in telomerase gene expression can affect stability of chromosomes and produces abnormal growth. Therefore, defects in both methylation and telomerase gene expression can lead to developmental abnormalities. We hypothesized that mutation in the methylation systems may induce developmental abnormalities through changing telomerase gene expression.

Materials and Methods:

In this experimental study, we used Arabidopsis thaliana (At) as a developmental model. DNA was extracted from seedlings leaves. The grown plants were screened using polymerase chain reaction (PCR) reactions. Total RNA was isolated from the mature leaves, stems and flowers of wild type and met1 mutants. For gene expression analysis, cDNA was synthesized and then quantitative reverse transcription PCR (qRT-PCR) was performed.

Results:

Telomerase gene expression level in homozygous met1 mutant plants showed ~14 fold increase compared to normal plants. Furthermore, TERT expression in met1 heterozygous was~ 2 fold higher than the wild type plants.

Conclusion:

Our results suggested that TERT is a methyltransferase-regulated gene which may be involved in developmental abnormities causing by mutation in met1 methyltransferase system.

New insights into the roles of the FOXO3 and P27Kip1 genes in signaling pathways

Background: The forkhead box O3 (FOXO3) and p27Kip1 are two important genes in breast cancer progression. In the present study we analyzed the effect of simultaneous FOXO3 silencing and p27Kip1 activation on breast cancer cell survival and the potential targets of these changes in cancer molecular pathways. Materials and methods: The present study involved the cloning of FOXO3a shRNA and p27Kip1 genes under the control of the bidirectional survivin promoter to down- and up-regulate FOXO3 and p27Kip1 genes, respectively. After transfection of the recombinant expression vector into the breast cancer cell line, the inhibition of cell growth was assessed by MTS and flow cytometry assays. Following the extraction of total mRNA and protein, the expression of target genes was evaluated by qPCR and Western blotting in both treated and untreated cell lines. Then, the downstream protein responses were examined by 2 D electrophoresis. The differentially expressed proteins were also identified by mass spectrometry. Results: Rates of cell proliferation were significantly inhibited in the transfected cell line 72 h post-transfection. Proteomic profiling of the cell line resulted in the identification of seven novel protein markers in breast cancer responsive to these changes in expression of FOXO3 and p27Kip1. The changes in expression of these markers suggested that certain signaling pathways contribute to the development of breast cancer. Conclusion: Simultaneous silencing of FOXO3 and activation of p27Kip1 in MDA-MB-231 cells caused alterations in the expression level of several genes involved in apoptosis, cell proliferation, cell cycle control, tissue invasion, drug resistance, and metastasis. It seems that the identified genes might serve as useful biomarkers for breast cancer.

Expression of LRP Gene in Breast Cancer Patients Correlated with MRP1 as Two Independent Predictive Biomarkers in Breast Cancer

Background:

Breast cancer is the most common malignancy in women. Multidrug resistance (MDR) is still a great obstacle of breast cancer chemotherapy. We have previously shown that multidrug resistance-associated protein 1 (MRP1) is associated with response to neoadjuvant chemotherapy. The lung resistance-related protein (LRP) is identified as a prognostic marker and response to treatment factor which has been studied mainly in hematological malignancy and leukemia. In this study, we aimed to analyze LRP expression and possible correlation between the expression level of this gene with MRP1 as a candidate marker for chemotherapy resistance.

Materials and Methods:

We collected 54 breast tumors and adjacent normal tissues from Iranian breast cancer patients and Real time RT-PCR was employed to measure the gene expression level in our samples.

Results:

MRP1 and LRP expression level were significantly lower in tumor tissues of the patients responding to chemotherapy compared to non-responding patients. No relation between the expression level of either of these genes and clinicopathology markers was found.

Conclusion:

Our results suggest that LRP gene expression is correlated to MRP1 in human breast cancer cells and may affect the clinical response to treatment.

Effect of MDR1 polymorphism on multidrug resistance expression in breast cancer patients

One of the limitations in the treatment of cancer patients with chemotherapy is the development of multidrug resistance (MDR). A well-known mechanism responsible for drug resistance is over-expression of ABC-transporter genes such as MDR1. This gene encodes p-glycoprotein (P-gp), a transmembrane glycoprotein that transports many hydrophobic substrates and anti-cancer drugs out of the cell. MDR1 gene polymorphisms could alter the expression level of P-gp and consequently result in drug resistance. We investigated a possible association between MDR1 gene C3435T polymorphism and its expression in Iranian breast cancer patients. PCR-RFLP was used for the detection of C3435T single nucleotide polymorphism in 54 breast cancer patients and 50 healthy individuals. The expression level of MDR1 was determined by real-time quantitative PCR. We observed no difference in the frequency of C3435T polymorphism between breast cancer patients and healthy controls. However, there was a significant association between MDR1 expression levels and C3435T polymorphism in the patients. C3435T polymorphism may play a role in inducing drug resistance by altering the expression level of the MDR1 gene.