Cutaneous squamous cell carcinoma (cSCC) is a malignant skin cancer which is derived from epidermal keratinocytes, and long-term exposure to ultraviolet rays is its main risk factor. Procollagen-lysine, 2-oxoglutarate 5-dioxygenase 2 (PLOD2) is a crucial gene for the formation and stability of collagen intermolecular cross-links, being vital in the development of cancer. Nevertheless, the interaction between cSCC and PLOD2 has not been elucidated. Here, we found PLOD2 upregulated in human cSCC. Its knockdown in cSCC cells suppressed proliferation, migration, invasion, and angiogenesis while inducing apoptosis and cell cycle arrest; overexpression promoted these malignant phenotypes. In mouse xenografts, PLOD2 knockdown inhibited tumor growth and collagen deposition. Furthermore, in a DMBA/TPA-induced carcinogenesis model, topical PLOD2 inhibition by minoxidil suppressed tumor development as well. Mechanistically, our studies revealed that PLOD2 acts as a key downstream effector of STAT3 to activate ERK and AKT signaling evidenced by rescue experiments. As a result, our study not only establishes the STAT3/PLOD2/ERK-AKT axis as a key driver of cSCC but also identifies the clinically approved drug minoxidil as a potent PLOD2 inhibitor, demonstrating immediate promise as a repurposed therapeutic agent.
Xian et al. (Sun,) studied this question.