Abstract. Allicin, the main active principle associated with Allium sativum chemistry, has various antitumor activities. However, to the best of our knowledge, there is no available information to address the anti-invasive effect and associated mechanism in lung adenocarcinoma. In the present study, cell viability assay, cell adhesion assay, western blot analysis, Transwell migration and invasion assays and reverse transcription-quantitative polymerase chain reaction were performed. Allicin was identified to inhibit the adhesion, invasion and migration of lung adenocarcinoma cells in a dose-dependent manner, accompanied by decreasing mRNA and protein levels of matrix metalloproteinase (MMP)-2 and MMP-9. Conversely, the mRNA and protein levels of tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 were increased in a dose-dependent manner. Furthermore, it was revealed that allicin treatment significantly suppressed the phosphorylation of AKT (P<0.05), but not the total protein expression of AKT. Combined treatment with LY294002, an inhibitor of phosphoinositide 3-kinase (PI3K)/AKT signaling, and allicin led to the synergistic reduction of MMP-2 and MMP-9 expression, followed by an increase in TIMP-1 and TIMP-2 expression. The invasive capabilities of lung adenocarcinoma cells were also suppressed. However, insulin-like growth factor-1 (an activator of PI3K/AKT signaling) reversed the effects of allicin on cell invasion and expression of MMP-2, MMP-9, TIMP-1 and TIMP-2. The present study concluded that allicin may inhibit invasion of lung adenocarcinoma cells by altering TIMP/MMP balance, via reducing the activity of the PI3K/AKT signaling pathway. This indicated that allicin may be recognized as an anti-invasive agent for lung adenocarcinoma treatment.
IntroductionLung cancer is the predominant reason of cancer-associated mortality in developed and developing countries. Lung adenocarcinoma is the most common histological type of lung cancer, and accounts for ~50% of all lung cancers (1). Although the management and treatment of surgery, radiotherapy and chemotherapy have improved, the therapeutic efficacy is poor. One of the major reasons is the lack of adequate treatment against lung adenocarcinoma invasion (2,3). Therefore, the development of novel adjuvant therapeutic strategies specifically targeting the progression of invasion is of critical importance for improving the prognosis of patients with lung adenocarcinoma.Invasion occurs through a complex pathophysiological process involving multiple genetic alterations (4,5). Matrix metalloproteinases (MMPs), particularly MMP-2 and MMP-9, play an important role in the invasion process of numerous malignant tumors by degrading the basement membrane and extracellular matrix (ECM) (6-8). Previous studies have suggested that MMP-2 and MMP-9 are associated with invasion in lung cancer (4,5). In addition, numerous studies have demonstrated that MMPs may be regulated by tissue inhibitor of metalloproteinase (TIMP) (6,9). Disturbing the balance of MMPs and TIMPs ma...