TIGAR knockdown enhanced the anticancer effect of aescin via regulating autophagy and apoptosis in colorectal cancer cells.

Our previous study showed that TP53-induced glycolysis and apoptosis regulator (TIGAR) regulated ROS, autophagy, and apoptosis in response to hypoxia and chemotherapeutic drugs. Aescin, a triterpene saponin, exerts anticancer effects and increases ROS levels. The ROS is a key upstream signaling to activate autophagy. Whether there is a crosstalk between TIGAR and aescin in regulating ROS, autophagy, and apoptosis is unknown. In this study, we found that aescin inhibited cell viability and colony formation, and induced DNA damage, cell cycle arrest, and apoptosis in cancer cell lines HCT-116 and HCT-8 cells. Concurrently, aescin increased the expression of TIGAR, ROS levels, and autophagy activation. Knockdown of TIGAR enhanced the anticancer effects of aescin in vitro and in vivo, whereas overexpression of TIGAR or replenishing TIGAR downstream products, NADPH and ribose, attenuated aescin-induced apoptosis. Furthermore, aescin-induced ROS elevation and autophagy activation were further strengthened by TIGAR knockdown in HCT-116 cells. However, autophagy inhibition by knockdown of autophagy-related gene ATG5 or 3-methyladenine (3-MA) exaggerated aescin-induced apoptosis when TIGAR was knocked down. In conclusion, TIGAR plays a dual role in determining cancer cell fate via inhibiting both apoptosis and autophagy in response to aescin, which indicated that inhibition of TIGAR and/or autophagy may be a junctional therapeutic target in treatment of cancers with aescin.

Aescin-induced reactive oxygen species play a pro-survival role in human cancer cells via ATM/AMPK/ULK1-mediated autophagy.

Aescin, a natural mixture of triterpene saponins, has been reported to exert anticancer effect. Recent studies show that aescin increases intracellular reactive oxygen species (ROS) levels. However, whether the increased ROS play a role in the anticancer action of aescin remains to be explored. In this study, we demonstrated that aescin (20-80 µg/mL) dose-dependently induced apoptosis and activated mammalian target of rapamycin (mTOR)-independent autophagy in human hepatocellular carcinoma HepG2 cells and colon carcinoma HCT 116 cells. The activation of autophagy favored cancer cell survival in response to aescin, as suppression of autophagy with ATG5 siRNAs or 3-methyladenine (3-MA), a selective inhibitor of autophagy, promoted aescin-induced apoptosis in vitro, and significantly enhanced the anticancer effect of aescin in vivo. Meanwhile, aescin dose-dependently elevated intracellular ROS levels and activated Ataxia-telangiectasia mutated kinase/AMP-activated protein kinase/UNC-51-like kinase-1 (ATM/AMPK/ULK1) pathway. The ROS and ATM/AMPK/ULK1 pathway were upstream modulators of the aescin-induced autophagy, as N-acetyl-L-cysteine (NAC) or ATM kinase inhibitor (KU-55933) remarkably suppressed aescin-induced autophagy and consequently promoted aescin-induced apoptosis, whereas overexpression of ATG5 partly attenuated NAC-induced enhancement in aescin-induced apoptosis. In conclusion, this study provides new insights into the roles of aescin-mediated oxidative stress and autophagy in cancer cell survival. Our results suggest that combined administration of the antioxidants or autophagic inhibitors with aescin might be a potential strategy to enhance the anticancer effect of aescin.

Rottlerin upregulates DDX3 expression in hepatocellular carcinoma.

Rottlerin has been reported to exert its anti-tumor activity in various types of human cancers. However, the underlying molecular mechanism has not been fully elucidated. In the current study, we explored whether rottlerin exhibits its tumor suppressive function in hepatocellular carcinoma cells. Our MTT assay results showed that rottlerin inhibited cell growth in hepatocellular carcinoma cells. Moreover, we found that rottlerin induced cell apoptosis and caused cell cycle arrest at G1 phase. Furthermore, our wound healing assay result demonstrated that rottlerin retarded cell migration in hepatocellular carcinoma cells. Additionally, rottlerin suppressed cell migration and invasion. Notably, we found that rottlerin upregulated DDX3 expression and subsequently downregulated Cyclin D1 expression and increased p21 level. Importantly, down-regulation of DDX3 abrogated the rottlerin-mediated tumor suppressive function, whereas overexpression of DDX3 promoted the anti-tumor activity of rottlerin. Our study suggests that rottlerin exhibits its anti-cancer activity partly due to upregulation of DDX3 in hepatocellular carcinoma cells.

Downregulation of MACC1 inhibits the viability, invasion and migration and induces apoptosis in esophageal carcinoma cells through the phosphatase and tensin homolog/phosphoinositide 3-kinase/protein kinase B signaling pathway.

As an oncogene, MACC1 serves an important function in cancer progression and metastasis. However, the effect of MACC1 in esophageal carcinoma (EC) remains to be fully understood. The present study assessed the association between MACC1 expression and the progression of EC cells. A small interfering (si)RNA was delivered into EC cells to downregulate MACC1 expression. The MTT assay demonstrated that EC cell viability was reduced by siRNA-MACC1. Decreasing MACC1 expression increased the apoptotic rate of EC cells compared with control cells. Transwell and Matrigel assays demonstrated that EC cell migration and invasion, respectively, were downregulated by siRNA-MACC1. Furthermore, knocking down MACC1 suppressed the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway by upregulating the expression of phosphatase and tensin homolog (PTEN), a tumor suppressor. The results of the present study revealed that MACC1 expression affected cellular functions of the EC cells through the PTEN/PI3K/Akt signaling pathway. Therefore, MACC1 may potentially serve as a novel biomarker and therapeutic target for EC.

Transcription factor EB is involved in autophagy-mediated chemoresistance to doxorubicin in human cancer cells.

Transcription factor EB (TFEB) is a master regulator of autophagy activity and lysosomal biogenesis, but its role in autophagy-mediated cell survival and chemotherapy resistance is not completely understood. In this study, we explored whether TFEB played an important role in autophagy-mediated chemotherapy resistance in human cancer LoVo and HeLa cells in vitro. Treatment of human colon cancer LoVo cells with doxorubicin (0.5 µmol/L) induced autophagy activation and nuclear translocation of TFEB, which resulted from inactivation of the mTOR pathway. In both LoVo and HeLa cells, overexpression of TFEB enhanced doxorubicin-induced autophagy activation and significantly decreased doxorubicin-induced cell death, whereas knockdown of TFEB with small interfering RNA blocked doxorubicin-induced autophagy and significantly enhanced the cytotoxicity of doxorubicin. In LoVo cells, autophagy inhibition by 3-methyladenine (3-MA) or knockdown of autophagy-related gene Atg5 increased cell death in response to doxorubicin, and abolished TFEB overexpression-induced chemotherapy resistance, suggesting that the inhibition of autophagy made cancer cells more sensitive to doxorubicin. The results demonstrate that TFEB-mediated autophagy activation decreases the sensitivity of cancer cells to doxorubicin.

The prognostic importance of jaundice in surgical resection with curative intent for gallbladder cancer.

BACKGROUND: Preoperative jaundice is frequent in gallbladder cancer (GBC) and indicates advanced disease. Resection is rarely recommended to treat advanced GBC. An aggressive surgical approach for advanced GBC remains lacking because of the association of this disease with serious postoperative complications and poor prognosis. This study aims to re-assess the prognostic value of jaundice for the morbidity, mortality, and survival of GBC patients who underwent surgical resection with curative intent. METHODS: GBC patients who underwent surgical resection with curative intent at a single institution between January 2003 and December 2012 were identified from a prospectively maintained database. RESULTS: A total of 192 patients underwent surgical resection with curative intent, of whom 47 had preoperative jaundice and 145 had none. Compared with the non-jaundiced patients, the jaundiced patients had significantly longer operative time (p < 0.001) and more intra-operative bleeding (p = 0.001), frequent combined resections of adjacent organs (23.4% vs. 2.8%, p = 0.001), and postoperative complications (12.4% vs. 34%, p = 0.001). Multivariate analysis showed that preoperative jaundice was the only independent predictor of postoperative complications. The jaundiced patients had lower survival rates than the non-jaundiced patients (p < 0.001). However, lymph node metastasis and gallbladder neck tumors were the only significant risk factors of poor prognosis. Non-curative resection was the only independent predictor of poor prognosis among the jaundiced patients. The survival rates of the jaundiced patients with preoperative biliary drainage (PBD) were similar to those of the jaundiced patients without PBD (p = 0.968). No significant differences in the rate of postoperative intra-abdominal abscesses were found between the jaundiced patients with and without PBD (n = 4, 21.1% vs. n = 5, 17.9%, p = 0.787). CONCLUSIONS: Preoperative jaundice indicates poor prognosis and high postoperative morbidity but is not a surgical contraindication. Gallbladder neck tumors significantly increase the surgical difficulty and reduce the opportunities for radical resection. Gallbladder neck tumors can independently predict poor outcome. PBD correlates with neither a low rate of postoperative intra-abdominal abscesses nor a high survival rate.