Fig. 8.

A schematic diagram showing how cigarette smoke increases OPN expression and stimulates the recruitment of MSCs to lung cancer cells. Our model illustrates the potential mechanisms that facilitate cigarette smoke-induced promotion of OPN expression and MSC recruitment by lung cancer cells. Arrow 1 refers to the effects of long-term CSE and B[α]P exposure, with subsequent increases in OPN expression in lung cancer cells via the JAK2/STAT3 signaling pathway. Arrow 2 refers to the process whereby integrin-positive and CD44-positive MSC cells are recruited to the lung TME and adhere to lung cancer cells. Arrow 3 refers to the events that occur when OPN induces MSC formation to TA-MSCs, which stimulates the invasiveness of lung cancer cells in vitro and lung tumor metastasis in vivo (3).