Gallic acid suppresses the progression of clear cell renal cell carcinoma through inducing autophagy via the PI3K/Akt/Atg16L1 signaling pathway

Clear cell renal cell carcinoma (ccRCC), the most common type of renal cell carcinoma (RCC), is not sensitive to traditional radiotherapy and chemotherapy. The polyphenolic compound Gallic acid (GA) can be naturally found in a variety of fruits, vegetables and plants. Autophagy, an intracellular catabolic process, regulates the lysosomal degradation of organelles and portions in cytoplasm. It was reported that autophagy and GA could affect the development of several cancers. Therefore, the aim of the present study was to evaluate the effects of GA on ccRCC development and clarify the role of autophagy in this process. In the present study, the effects of GA on the proliferation, migration and invasion of ccRCC cells were investigated in vitro by Cell Counting Kit-8, colony formation, flow cytometry, wound healing and Transwell migration assays, respectively. Additionally, the effects of GA on ccRCC growth and metastasis were evaluated using hematoxylin-eosin and immunohistochemical staining in vivo. Moreover, it was sought to explore the underlying molecular mechanisms using transmission electron microscopy, western blotting and reverse transcription-quantitative PCR analyses. In the present study, it was revealed that GA had a more potent viability inhibitory effect on ccRCC cells (786-O and ACHN) than the effect on normal renal tubular epithelial cell (HK-2), which demonstrated that GA selectively inhibits the viability of cancer cells. Furthermore, it was identified that GA dose-dependently inhibited the proliferation, migration and invasion of ccRCC cells in vitro and in vivo. It was demonstrated that GA promoted the release of autophagy markers, which played a role in regulating the PI3K/Akt/Atg16L1 signaling pathway. All the aforementioned data provided evidence for the great potential of GA in the treatment of ccRCC.