shikonin and Adenocarcinoma-of-Lung

Increasing evidence indicates that the inflammatory tumor microenvironment can lead to cancer cell metastasis. Shikonin, which is extracted from the Chinese herb Zicao (the dried root of Lithospermum erythrorhizon), possesses various pharmacological effects, but its effect on tumor metastasis in the inflammatory microenvironment remains unknown. In the present study, we aimed to investigate the potential effect of shikonin on tumor metastasis in an inflammatory microenvironment as well as the underlying molecular mechanisms. It was found that, in the inflammatory microenvironment simulated by THP‑1 cell conditioned medium (THP‑1‑CM) in vitro, shikonin significantly inhibited the epithelial‑mesenchymal transition (EMT), migration and invasion of human lung adenocarcinoma cell lines A549 and H1299. In addition, we found that interleukin‑6 (IL‑6), which is expressed in THP‑1‑CM, promoted the EMT of lung adenocarcinoma cells, and shikonin markedly inhibited IL‑6‑induced EMT and cell motility. Moreover, shikonin inhibited IL‑6‑induced phosphorylation of signal transducer and activator of transcription 3 (STAT3), prevented phosphorylated STAT3 (p‑STAT3) translocation into the nucleus, and suppressed p‑STAT3 transactivation activity. Additionally, it was found that shikonin inhibited lung metastasis, EMT and expression of p‑STAT3 of A549 cells in vivo. Furthermore, IL‑6 levels in human lung adenocarcinoma tissues were significantly associated with tumor‑node‑metastasis stage and lymph node metastasis, and its expression was correlated with tumor‑associated macrophage (TAM) infiltration. Together, these results suggest that shikonin suppresses the migration and invasion of human lung adenocarcinoma cells in an inflammatory microenvironment involving the IL‑6/STAT3 signaling pathway.

Topics: A549 Cells; Adenocarcinoma of Lung; Cell Movement; Drugs, Chinese Herbal; Epithelial-Mesenchymal Transition; Female; Humans; Interleukin-6; Lung; Lung Neoplasms; Lymphatic Metastasis; Male; Middle Aged; Naphthoquinones; Neoplasm Invasiveness; Signal Transduction; STAT3 Transcription Factor; THP-1 Cells; Tumor Microenvironment; Tumor-Associated Macrophages; Xenograft Model Antitumor Assays

Shikonin, a natural naphthoquinone isolated from a traditional Chinese medicinal herb, can exert inhibitory effect on tumor cell growth. However, little has been known concerning the effect of shikonin on lung adenocarcinoma cell and underlying mechanisms. In the present study, we investigated the effect of shikonin on the proliferation, cell cycle arrest, and apoptosis in human lung adenocarcinoma cells. We found that shikonin significantly suppressed the proliferation of lung adenocarcinoma cells compared with control in dose- and time-dependent manner (P < 0.05). In the meantime, our results showed that shikonin markedly increased the proportion of A549 cells at stage G1 as well as induced apoptosis in A549 cells. Furthermore, suppressed CCND1 and elevated caspase3 and caspase7 expression levels at mRNA were found in this study, indicating that shikonin may inhibit the growth of lung adenocarcinoma cell by changing cell cycle and promoting cell apoptosis through the regulation of CCND1, caspase3, and caspase7. Although more studies are needed, this study suggests that shikonin has the potential to be used as an anti-cancer agent in the treatment of lung adenocarcinoma.

Topics: Adenocarcinoma; Adenocarcinoma of Lung; Antineoplastic Agents; Apoptosis; Caspases; Cell Line, Tumor; Cell Proliferation; Enzyme Activation; G1 Phase Cell Cycle Checkpoints; Gene Expression Regulation, Neoplastic; Humans; Lung Neoplasms; Naphthoquinones; Resting Phase, Cell Cycle