It isn't over ‘till it’s over: A continuing concern of the SARS-CoV-2 variants, and miRNAs targeting the S protein as a probable absolute cure

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak which still continues to affect the general population, has mutated day by day and new variants have emerged. More than 40 variants, usually caused by mutations in the spike (S) protein, have been recorded. Observation of S protein mutations in the development of t herapeutic agents will increase success rates. As we identify the three-dimensional (3D) conformation of viruses, it is more and more possible to work on models for understanding molecular interactions. Development of agents for arrays and 3D sequencing of proteins paves the way for potential therapeutic studies against variants. MicroRNAs (miRNAs) seemingly act as a potentially important group of biomolecules in combating uncontrolled cytokine release. Besides antiviral response, miRNAs promise to be  powerful therapeutic agents against infections. Studies have shown that miRNAs are able to inhibit the genome directly by miRNA-based treatments as they are sprecific to the SARS-CoV-2 genome. In order to expose this potential, in silico studies before continuing with lab studies are helpful. In our bioinformatics analysis, we proposed to compare the S protein similarities of Delta and Omicron, two of the most common variants, and to detect miRNAs targeting the S protein. The S proteins and coding sequences were compared between the two variants, and differences were determined. Within our analysis, 105 and 109 miRNAs for the Delta and Omicron variants, respectively, were detected. We believe that our study will be a potential guide for deciding on the miRNAs that may most likely have an effect on the management of the infection caused by both variants

Two different docetaxel resistant MCF-7 sublines exhibited different gene expression pattern

The objective of the present study was to investigate gene expression pattern of two docetaxel resistant MCF-7 breast carcinoma sublines step wisely selected in 30 and 120 nM docetaxel. Cell proliferation assay was performed in order to demonstrate development of docetaxel resistance. cDNA microarray analysis was performed using Affymetrix(A (R)) Human Genome U133 Plus 2.0 Arrays in duplicate experiments. Quantitative and semi-quantitative gene expression analysis was also performed to confirm gene expression analysis for selected genes. XTT results demonstrated that 30 (MCF-7/30nM DOC) and 120 nM (MCF-7/120nM DOC) docetaxel selected cells were 13- and 47-fold resistant, respectively. cDNA microarray analysis demonstrated that expression profiles of MCF-7 and MCF-7/30nM DOC were more similar to each other where expression profile of MCF-7/120nM DOC was different as examined by line graphs and scatter plots. 2,837 and 4,036 genes were significantly altered in 30 and 120 nM docetaxel resistant sublines, respectively. Among these, 849 genes were altered in common in two docetaxel resistant sublines. Antiapoptotic gene expression (e.g., Bcl-2 and APRIL) were noticeably altered in MCF-7/30nM DOC. However, docetaxel resistance in MCF-7/120nM DOC were more complicated with the involvement of ECM related gene expression, cytokine and growth factor signaling, ROS metabolism and EMT related gene expression together with higher level of MDR1 expression. Expression profiles in 30 and 120 nM docetaxel resistant sublines changed gradually with increasing resistance index. Drug resistance development seems to be step wise event in MCF-7 cells

Drug resistant breast cancer cells overexpress ETS1 gene

Purpose. - Multidrug resistance (MDR) is resistance to wide range of structurally unrelated anticancer agents. MDR is a serious limitation to the effective chemotherapy. Involvement of ETS1 overexpression in upregulation of MDR1 gene expression is implicated. In the present study the aim was to assess the involvement of ETS1 and the genes, which encode the proteins interacting with ETS1 in drug resistant MCF-7 breast cancer cells

A microarray based expression profiling of paclitaxel and vincristine resistant MCF-7 cells

Resistance to the broad spectrum of chemotherapeutic agents in cancer cell lines and tumors has been called multiple drug resistance (MDR). In this study, the molecular mechanisms of resistance to two anticancer agents (paclitaxel and vincristine) in mammary carcinoma cell line MCF-7 were investigated. Drug resistant sublines to paclitaxel (MCF-7/Pac) and vincristine (MCF-7/Vinc) that were developed from sensitive MCF-7 cells (MCF-7/S) were used. cDNA microarray analysis was performed for the RNA samples of sensitive and resistant cells in duplicate experiments. GeneSpring GX 7.3.1 Software was used in data analysis. The results indicated that the upregulation of MDR] gene is the dominating mechanism of the paclitaxel and vincristine drug resistance. Additionally the upregulation of the genes encoding the detoxifying enzymes (i.e. GSTP1) was observed. Significant downregulation of apoptotic genes (i.e. PDCD2/4/6/8) and upregulation of some cell cycle regulatory genes (CDKN2A, CCNA2 etc.) was seen which may be in close relation to MDR in breast cancer. Drug resistant cancer cells exhibit different gene expression patterns depending on drug treatment, and each drug resistance phenotype is probably genetically different. Further functional studies are needed to demonstrate the complete set of genes contributing to the drug resistance phenotype in breast cancer cells

Reversal of multidrug resistance by synthetic and natural compounds in drug-resistant MCF-7 cell lines

Background: Ineffectiveness of anticancer drugs is frequently observed in cancer chemotherapy. The resistance of tumor cells to various cytotoxic drugs is defined as multidrug resistance (MDR). The purpose of this study is to investigate the potential reversal effect of some synthetic and natural chemicals on drug-resistant MCF-7 cell lines. The effects of potential MDR modulators combined with some anticancer drugs were also studied. Methods: Flow cytometry, MTT cytotoxicity assays and checkerboard combination assays were performed to study the reversal of drug resistance and to investigate the antiproliferative effects of the combination of anticancer drugs and the potential modulators. The results indicated that verapamil, capsanthin, zeaxanthin and promethazine inhibited P-gp effectively, but chrysin was not effective at reversing the resistance in MCF-7 sublines. Four selective anticancer drugs ( paclitaxel, docetaxel, doxorubicin and vincristine) and 4 effective MDR modulators ( verapamil, capsanthin, zeaxanthin and promethazine) were applied to the sublines in combination. Results and Conclusion: Fractional inhibitory indices show that verapamil and zeaxanthin seem to be the most effective MDR reversal agents that may be used together with paclitaxel, docetaxel, vincristine and doxorubicin in drug-resistant mammary carcinoma sublines. In conclusion, this report represents the importance to find out active and efficient drug resistance modulators for improving the efficacy of chemotherapy. Copyright (C) 2008 S. Karger AG, Basel

High salt induced oxidative damage and antioxidant response in tomato grafted on tobacco

One of the major limitations on agricultural development in many countries is the high salinity of the groundwater used in irrigation. Grafted plants may exhibit phenotypic variations from scion and rootstock plants in terms of abiotic stress tolerance, and be a method for improvement of tolerance in agricultural practices. The aim of the present study was to investigate response of Solanum lycopersicum L. ('Elazig') grafted on Nicotiana tabacum L. ('Samsun') and Nicotiana rustica L. ('Hasankeyf'), namely "Tomacco" plant (patent nr TR-2008-05391-B), to 10-d high NaCl irrigation. Physical development, chlorophyll a and b, total chlorophyll, total carotenoid, and anthocyanin levels were evaluated. Proline, lipid peroxidation, and electrolyte leakage levels were assayed in roots and leaves together with ascorbate peroxidase (APX) and catalase (CAT) activities. Considering alterations in chlorophyll contents, proline, malondialdehyde (MDA), and conductivity levels, and antioxidant enzyme activity levels scion and self-grafted plants seem to be more affected by salt treatments than tobacco and rootstock grafted plants. Tobacco roots seem to have better adaptive responses against salt stress in comparison to tomato as supported by changes in proline, APX, and CAT levels. Self-grafting experiments further supported grafting tomato onto tobacco rootstocks enhanced salt tolerance and adaptive response of scions and these changes seem to be dependent on rootstock rather than graft-induced changes. In conclusion, we demonstrated that previously defined graft unions of tomato on tobacco, which have increased fruit yield, had also enhanced tolerance to high salt stress and a promising technique for the cultivation of more salt tolerant varieties

In vitro evaluation of zoledronic acid resistance developed in MCF-7 cells

Background: Zoledronic acid is an important osteotropic compound used in combination with anticancer agents to reduce the incidence of hypercalcemia and skeletal morbidity in patients with advanced breast cancer and bone metastases. Ineffectiveness of anticancer drugs during chemotherapy is a frequently observed situation in cancer chemotherapy. The resistance of tumor cells to more than one cytotoxic drugs is defined as multidrug resistance. Drug resistance may be caused by altered gene expression levels and altered activities of proteins related to drug transport or cell death. Materials and Methods: To investigate the potential development of zoledronic acid resistance in breast cancer, parental MCF-7 cells were selected by increasing doses of zoledronic acid. MTT cytotoxicily assays, RT-PCR and Western blot were performed. The anticancer drugs paclitaxel, docetaxel, vincristine and doxorubicin were tested in combination to assess their combined antiproliferative effects and cross-resistance profiles. Results: Results demonstrated that the drug-adapted cells are resistant to zoledronic acid compared to parental MCF-7 and de novo expression of resistance genes, such as BCRP and LRP, were found. Up-regulation of Bcl-2 gene expression in resistant cells was also found. Synergistic cytotoxic effects of the combination of zoledronic acid with paclitaxel, docetaxel and vincristine were confirmed by fractional inhibitory indices, and zoledronic acid resistant cells were also found to be cross-resistant to these agents. Conclusion: Zoledronic acid may cause resistance in MCF-7 cells. Overexpression of BCRP and LRP genes and an increase in Bcl-2 gene expression may have roles in the development of zoledronic acid resistance in the MCF-7 cell line. On the other hand, MDR1 and MRP1 genes do not seem to contribute to the zoledronic acid resistance significantly

Effect of doxorubicin on telomerase activity and apoptotic gene expression in doxorubicin-resistant and -sensitive MCF-7 cells

Background: Dose-and time-dependent effects of doxorubicin on telomerase activity ( TA) and expression levels of hTERT, Bcl-2, Bcl-x(L) and Bax were investigated in doxorubicin-resistant and -sensitive MCF-7 cells. Methods: Doxorubicin-resistant MCF-7/R was developed from sensitive MCF-7 breast carcinoma cell line and acquired resistance was demonstrated by XTT and mRNA analysis of MDR1 and MRP1 genes. Expression levels were determined by RT-PCR. Newly developed rapid and simple TRAP-silver staining assay was used to assess TA levels. Results: Doxorubicin-selected MCF-7 cells were 107-fold resistant to the drug and overexpress MDR1 and MRP1 genes. 72 h doxorubicin incubation caused a decrease in TA in parallel with a small decrease in hTERT level in both sensitive and resistant cells. Bcl-2 expression level decreased upon doxorubicin application in sensitive cells. However, the Bcl-x(L) level increased in sensitive cells after 72 h of doxorubicin incubation. Conclusion: This report demonstrates the inhibitory effects of doxorubicin on TA in both resistant and sensitive MCF-7 cells possibly through modulation of the apoptotic pathway genes. Copyright (C) 2008 S. Karger AG, Basel

Effect of MDR modulators verapamil and promethazine on gene expression levels of MDR1 and MRP1 in doxorubicin-resistant MCF-7 cells

One of the major problems of cancer chemotherapy is the development of multidrug resistance (MDR) phenotype. Among the numerous mechanisms of MDR, a prominent one is the increased expression of membrane transporter proteins, the action of which leads to decreased intracellular drug concentration and cytotoxicity of drugs. Among them, P-gp and MRP1, encoded by MDR1 and MRP1 genes, respectively, have been associated with MDR phenotype. Chemical modulators can be used to reverse MDR. These chemicals can either modulate MDR due to their substrate analogy (such as calcium channel blocker verapamil) or interact with phospholipid membranes (such as antihistaminic drug promethazine). This study focuses on the effect of verapamil and promethazine on the expression levels of MDR1 and MRP1 genes and the drug transport activity in doxorubicin-resistant MCF-7 breast carcinoma cell line

Epigallocatechin 3-gallate applications on HT-29 and MCF-7 cell lines and evaluation of tumor suppressor gene methylation

Epigallocatechin 3-gallate (EGCG) is an antitumor molecule and shows this activity by binding to the active center of a methyltransferase enzyme (DNMT1). The methylation of DNA sequences of tumor suppressor and DNA repair genes is observed in different stages of carcinogenesis. In this study, we analyzed the effect of EGCG on the methylation status of 25 tumor suppressor genes in cancer cell lines HT-29 and MCF-7. HT-29 and MCF-7 cells were incubated with 10 mu M, 20 mu M, and 50 mu M and 1 mu M, 5 mu M, and 10 mu M EGCG for 48 h, respectively. We found promoter hypermethylation of (1) CDH13, GATA5, and RAR beta genes in MCF-7 cell line and (2) RAR beta, ESR1, PAX6, WT1, CADM1, CHFR, CDH13, and GATA5 genes in HT-29 cell line. However, (3) after EGCG application, no changes in methylation status were detected in our samples. Our results suggest that methylation status of tumor suppressor genes did not change with different EGCG doses