Exploring the Potential of Montmorillonite as an Antiproliferative Nanoagent against MDA-MB-231 and MCF-7 Human Breast Cancer Cells.

Unlike MCF-7 cells, MDA-MB-231 cells are unresponsive to hormone therapy and often show resistance to chemotherapy and radiotherapy. Here, the antiproliferative effect of biocompatible montmorillonite (Mt) nanosheets on MDA-MB-231 and MCF-7 human breast cancer cells was evaluated by MTT assay, flow cytometry, and qRT-PCR. The results showed that the Mt IC50 for MDA-MB-231 and MCF-7 cells in a fetal bovine serum (FBS)-free medium was ~50 and ~200 µg/mL, and in 10% FBS medium ~400 and ~2000 µg/mL, respectively. Mt caused apoptosis in both cells by regulating related genes including Cas-3, P53, and P62 in MDA-MB-231 cells and Bcl-2, Cas-8, Cas-9, P53, and P62 in MCF-7 cells. Also, Mt arrested MCF-7 cells in the G0/G1 phase by altering Cyclin-D1 and P21 expression, and caused sub-G1 arrest and necrosis in both cells, possibly through damaging the mitochondria. However, fewer gene expression changes and more sub-G1 arrest and necrosis were observed in MDA-MB-231 cells, confirming the higher vulnerability of MDA-MB-231 cells to Mt. Furthermore, MDA-MB-231 cells appeared to be much more vulnerable to Mt compared to other cell types, including normal lung fibroblast (MRC-5), colon cancer (HT-29), and liver cancer (HepG2) cells. The higher vulnerability of MDA-MB-231 cells to Mt was inferred to be due to their higher proliferation rate. Notably, Mt cytotoxicity was highly dependent on both the Mt concentration and serum level, which favors Mt for the local treatment of MDA-MB-231 cells. Based on these results, Mt can be considered as an antiproliferative nanoagent against MDA-MB-231 cells and may be useful in the development of local nanoparticle-based therapies.

Considerations about Reducing False-Negative PCR Test for COVID-19.

Polymerase chain reaction (PCR) for the detection of nucleic acids is the gold standard test for the diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, there is the probability of false-negative results with this test, which poses a threat to public health. Here, we highlight some important factors that should be considered for reducing the false-negative results of the SARS-CoV-2 PCR test.

Montmorillonite, a natural biocompatible nanosheet with intrinsic antitumor activity.

Montmorillonite (Mt) nanosheets are used in pharmaceutical products as both excipient and active ingredients. In addition, Mt can be used as a nanocarrier for oral delivery of drugs, including chemotherapy drugs, and as an embolic agent for tumor arterial embolization. It is noteworthy that, there is few conflicting evidence on the intrinsic antitumor activity of Mt. Hence, in this study, the antitumor potential of Mt was investigated using MRC-5, HT-29 and HepG2 cell lines. MTT assay revealed that, Mt possesses antiproliferative effect, which was concentration-dependent and affected by both protein level and cell type. However, this antiproliferative effect was not significantly affected by increasing the exposure time from 24 to 48 h. The results of flow-cytometry and qRT-PCR analyses showed that, Mt induced G0/G1-phase arrest in MRC-5 and HT-29 cells by modulating P21, P27 and Cyclin D1 genes, whereas it induced S-phase arrest in HepG2 cells probably by damaging DNA and up-regulating mTOR gene. The results also indicated that, Mt induced a high rate of apoptosis in all the cell lines by modulating anti/pro-apoptotic genes, as well as a rate of necrosis in HT-29. The apoptosis of MRC-5 and HT-29 cells was accompanied with up-regulation of P62 gene, suggesting autophagy-dependent apoptosis. In addition, in all the cell lines, Mt significantly enhanced the expression of executioner caspase-3. Based on these results, the biocompatible Mt nanosheets can act as antitumor agents. These findings may provide new applications of Mt in the field of cancer therapy.

A quick, efficient, and cost-effective method for isolating high-quality total RNA from tomato fruits, suitable for molecular biology studies.

Tomato (Solanum lycopersicum L.) is the primary model for the study of fleshy fruits, and research on this species has elucidated many aspects of fruit physiology, development, and metabolism. However, for advancing such studies at molecular biology levels, the RNA isolation from fruit tissues is often essential. The RNA isolation from tomato fruits is complicated because of the presence of high levels of polysaccharides, polyphenolics, pigments, and secondary metabolites and also the varying water content during development. Here, we present an optimized protocol for the isolation of total RNA from the fruit tissues at different developmental stages. In comparison to the previous methods described for the RNA isolation from tomato fruit, this method has the advantages that it does not involve the use of guanidine salts, lyophilizers, and commercial reagents, reduces the time and cost of extraction, overcomes the high water content problem, and promotes RNA quality by inhibiting RNA degradation and minimizing the gDNA, polyphenolic and polysaccharide contaminations. Using this method, high yields of high-purity and intact RNA samples were obtained as confirmed by the spectrophotometric readings and the electrophoresis on denaturing agarose gels. The isolated RNA was employed as a robust template for cDNA synthesis, reverse transcriptase-polymerase chain reaction (RT-PCR), and temporal gene expression analysis. The functionality of the isolated RNA was further demonstrated through cloning full-length cDNAs encoding ß-galactosidase proteins by RT-PCR and sequencing.