Osteoarthritis is a highly prevalent and debilitating joint disorder. There is no effective medical therapy for osteoarthritis due to limited understanding of osteoarthritis pathogenesis. We show that TGF–β1 is activated in the subchondral bone in response to altered mechanical loading in an anterior cruciate ligament transection (ACLT) osteoarthritis mouse model. TGF–β1 concentrations also increased in human osteoarthritis subchondral bone. High concentrations of TGF–β1 induced formation of nestin+ mesenchymal stem cell (MSC) clusters leading to aberrant bone formation accompanied by increased angiogenesis. Transgenic expression of active TGF–β1 in osteoblastic cells induced osteoarthritis. Inhibition of TGF–β activity in subchondral bone attenuated degeneration of osteoarthritis articular cartilage. Notably, knockout of the TGF–β type II receptor (TβRII) in nestin+ MSCs reduced development of osteoarthritis in ACLT mice. Thus, high concentrations of active TGF–β1 in the subchondral bone initiated the pathological changes of osteoarthritis, inhibition of which could be a potential therapeutic approach.

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Recent large scale genomic studies from the Clinical Lung Cancer Genome Project have identified different driver gene mutations in the subtypes of non-small cell lung carcinoma (NSCLC). These findings not only lead to remarkable progress in targeted therapies for lung cancer patients, but also provide fundamental knowledge for the subclassification of NSCLC. More recently, the advancement and clinical application of immunotherapy have reinforced the need for the accurate subclassification of NSCLC. In 2015, the World Health Organization (WHO) and the International Association for the Study of Lung Cancer (IASLC) updated their guidelines for the subclassification of lung cancers. These guidelines emphasize: (1) the subclassification of NSCLC, (2) the critical role of molecular characterization of tumors for targeted therapy, (3) the unique terminology for subclassifying NSCLC using small biopsy specimens, and (4) the utility of IHC biomarkers in the accurate diagnosis and subclassification of lung cancer. The guidelines have significant prognostic impact on oncologic practice and patient care. In this review, we summarize the current WHO guidelines for the classification of lung cancer, discuss advancements of targeted therapy and immunotherapy, and address the utility and limitation of immunomarkers in the subclassification of NSCLC, as well as the prospective future of the field.