Downregulation of Inhibition of Apoptosis-Stimulating Protein of p53 (iASPP) Suppresses Cisplatin-Resistant Gastric Carcinoma In Vitro

Downregulation of iASPP Expression Suppresses Proliferation, Invasion and Increases Chemosensitivity to Paclitaxel of Head and Neck Squamous Cell Carcinoma In Vitro

Objective Our previous study has revealed that iASPP is elevated in human head and neck squamous cell carcinoma (HNSCC) and iASPP overexpression signifcantly correlates with tumor malignant progression and poor survival of HNSCC. This study investigated the function of iASPP playing in proliferation and invasion of HNSCC in vitro. Methods HNSCC cell line Tu686 transfected with Lentiviral vector-mediated iASPP-specific shRNA and control shRNA were named the shRNA-iASPP group and shRNA-NC group, respectively. The non-infected Tu686 cells were named the CON group. CCK-8 assay, flow cytometry, transwell invasion assay were performed to detect the effects of iASPP inhibition in vitro. Results Our results demonstrated that the proliferation of shRNA-iASPP cells at the time of 72 h (F=32.459, P=0.000), 96 h (F=51.407, P=0.000), 120 h (F=35.125, P=0.000) post-transfection, was significantly lower than that of shRNA-NC cells and CON cells. The apoptosis ratio of shRNA-iASPP cells was 9.42% ± 0.39% (F=299.490, P=0.000), which was significantly higher than that of CON cells (2.80% ± 0.42%) and shRNA-NC cells (3.18% ± 0.28%). The percentage of shRNA-iASPP cells in G0/G1 phase was 74.65% ± 1.09% (F=388.901, P=0.000), which was strikingly increased, compared with that of CON cells (55.19% ± 1.02%) and shRNA-NC cells (54.62% ± 0.88%). The number of invading cells was 56 ± 4 in the shRNA-iASPP group (F=84.965, P=0.000), which decreased significantly, compared with the CON group (111 ± 3) and the shRNA-NC group (105 ± 8). The survival rate of shRNA-iASPP cells administrated with paclitaxel was highly decreased, compared with CON cells and shRNA-NC cells (F=634.841, P=0.000). Conclusion These results suggest iASPP may play an important role in progression and aggressive behavior of HNSCC and may be an efficient chemotherapeutic target for the treatment of HNSCC.

Oridonin Sensitizes Cisplatin-Induced Apoptosis via AMPK/Akt/mTOR-Dependent Autophagosome Accumulation in A549 Cells

AMPK-mediated autophagy and Akt/mTOR pathways play important roles in current cancer treatments. Oridonin (Ori), an ent-kaurane diterpenoid isolated from Isodon rubescens, exerts extensive anti-tumor potential and controversial effects on autophagy. In this study, we investigated the effect of Ori on the autophagy, apoptosis, and AMPK/Akt/mTOR pathways and determined whether Ori was related to the increased cisplatin sensitivity observed in A549 cells. First, we found that Ori suppressed Akt/mTOR, Bcl2 and autophagy flux with enhanced levels of Atg3, P62, and LC3II, which was also shown as the accumulation of autophagosomes. AMPK and pro-apoptotic proteins (caspase3, Bax, and PARP) were activated in Ori-treated cells. With the pretreatment of compound c (AMPK inhibitor), the activation of autophagosomes, apoptosis and the inhibition of Akt/mTOR pathways induced by Ori were all reversed. The Ori-activated apoptosis-related markers mentioned previously and the cell-killing effect were restrained by 3-MA (inhibitor of autophagosomes) treatment. Therefore, we hypothesized that the Ori-induced pro-apoptotic effect was mediated by AMPK/Akt/mTOR-dependent accumulation of impaired autophagosomes. Furthermore, Ori could increase the sensitivity of cisplatin through its increased cell-killing, autophagy-suppressing and apoptosis-inducing activities. In addition to sensitizing cisplatin, Ori also alleviated cisplatin-induced acute renal injury in vivo, manifested as depleted BUN, CRE, kidney index, and weight loss compared to the cisplatin group. In summary, apart from its protective effect on cisplatin-induced nephrotoxicity, Ori enhanced cisplatin sensitivity via its pro-apoptotic activity mediated by AMPK/Akt/mTOR-dependent autophagosome activation, which may be a potential therapeutic target for non-small cell lung cancer.

Adapting and Surviving: Intra and Extra-Cellular Remodeling in Drug-Resistant Gastric Cancer Cells

Despite the significant recent advances in clinical practice, gastric cancer (GC) represents a leading cause of cancer-related deaths in the world. In fact, occurrence of chemo-resistance still remains a daunting hindrance to effectiveness of the current approach to GC therapy. There is accumulating evidence that a plethora of cellular and molecular factors is implicated in drug-induced phenotypical switching of GC cells. Among them, epithelial-mesenchymal transition (EMT), autophagy, drug detoxification, DNA damage response and drug target alterations, have been reported as major determinants. Intriguingly, resistant GC phenotype may be the result of GC cell-induced tumor microenvironment (TME) remodeling, which is currently emerging as a key player in promoting drug resistance and overcoming cytotoxic effects of drugs. In this review, we discuss the possible mechanisms of drug resistance and their involvement in determining current GC therapies failure.