Inability of human adipose tissue cells to differenciate between triiodothyronine (T3) and thyroxine (T4)

Long noncoding RNAs and exosomal lncRNAs: classification, and mechanisms in breast cancer metastasis and drug resistance

Breast cancer is the most common cancer, and the second cause of cancer-related deaths (after lung cancer) among women. Developing tumor metastasis and invasion is the most important cause of death in breast cancer patients. Several key factors participate in breast cancer metastasis including long noncoding RNAs (lncRNAs). lncRNAs are a category of cellular RNAs that are longer than 200 nucleotides in length. Accumulating evidence suggests that lncRNAs have the potential to be promising diagnostic, prognostic biomarkers and therapeutic targets in breast cancer. Understanding the role of lncRNAs and their mechanisms of functions might help to further discovery of breast cancer biological characteristics. In this review, we discuss physiological functions, epigenetic regulation, transcriptional regulation of lncRNAs, and their important role in tumor progression and metastasis. Some lncRNAs function as oncogenes and some function as tumor suppressors. Interestingly, recent reports depict that hypomethylation of promoters of lncRNAs play a pivotal role in cancer progression, suggesting the importance of epigenetic regulation. Furthermore, we discuss the role of lncRNAs in exosomes and their function in drug resistance, and therapeutic importance of exosomal lncRNAs in cancer biology. In summary, lncRNAs have a great potential to consider them as novel prognostic biomarkers as well as new therapeutic targets in breast cancer.

MOde of entry of steroid and thyroid hormones into cells

Characteristics of the processes by which steroid and thyroid hormones enter tissues, cells and membrane vesicles are reviewed. Several authors suggest that entry is by passive diffusion: the accumulation within cells is attributed to cytoplasmic binding proteins. Other authors, however, propose a membrane-mediated process of entry. The involvement of saturability, high specificity, sensitivity to temperature, sulfhydryl and cell-surface-perturbing reagents and hydrolytic enzymes support the latter view. Purified plasma-membrane vesicle preparations retain several characteristics of entry shown by intact cells. Intracellular hormone-binding protein would not contribute to processes observed with these preparations.