HB0030

By lysing cells, releasing RNA, and removing impurities such as proteins and DNA, high-purity RNA products are finally obtained. The commonly used traditional method is the guanidine isothiocyanate/phenol/chloroform method (Trizol), which is suitable for a variety of animal materials including animal tissues, microorganisms, cultured cells, etc., and most plant materials.

Cytotoxicity assays are usually based on the assessment of cell membrane damage, which can also be indirectly detected by measuring cell viability. Detection methods include MTT assay, CKK-8 assay, LDH assay and ATP assay, etc.

Live/dead viability and cytotoxicity staining assays are based on the simultaneous detection of intracellular esterase activity in metabolically active (viable) cells and membrane integrity loss in non-viable cells. In commonly used dual-staining approaches, membrane-permeant fluorogenic substrates are converted by intracellular esterases into fluorescent products in live cells, while impermeant DNA-binding dyes selectively enter cells with compromised plasma membranes and label nucleic acids in dead or dying cells, enabling discrimination between viable and non-viable populations by fluorescence microscopy or flow cytometry.

Naïve CD4+ T-cell subset differentiation/polarization is an in vitro assay in which purified naïve CD4+ T cells are activated through TCR and CD28 costimulation and cultured with defined cytokines and neutralizing antibodies to generate Th0, Th1, Th2, Th17, or induced Treg-like populations. Differentiation is detected by subset-associated cytokines and transcription factors: IFN-γ/T-bet for Th1, IL-4/GATA3 for Th2, IL-17A/RORγt for Th17, and Foxp3 for induced Treg cells. The assay readout is usually generated by intracellular cytokine staining after restimulation, transcription-factor staining by flow cytometry, ELISA of secreted cytokines, or gene-expression analysis. The result reflects cytokine-directed lineage commitment or polarization rather than antigen-specific immune protection by itself.

Liver cancer can be classified into primary liver cancer and secondary liver cancer. Secondary liver cancer is the metastatic liver cancer. Primary liver cancer includes hepatocellular carcinoma (HCC), intrahepatic cholangiocarcinoma (ICC) and fibrolamellar HCC, of which HCC is the most common form, accounting for approximately 90% of primary liver cancers^[1]. HCC mouse models include chemical agent-induced models, transplanted tumor models, and genetic engineered models.

Breast cancer is a heterogeneous cancer, and it has been distinguished into four subtypes: luminal A, luminal B, HER2-positive and basal-like. Molecular mutations, epigenetic alterations, hormone exposure and immune microenvironment are related to the progression of breast cancer.

The following protocol uses the MTT colorimetric assay as a classic literature-established method for assessing cell viability/metabolic activity in cultured mammalian cells. MTT[3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] is reduced by metabolically active cells to a colored formazan product; the amount of formazan is quantified spectrophotometrically and provides an indirect measure of metabolically active viable cells. Importantly, MTT reduction reflects cellular oxidoreductase/metabolic activity rather than an absolute direct count of living cells, so changes in cellular metabolism can alter the signal independently of cell number.