Long-term ethanol exposure causes human liver cancer cells to become resistant to mitomycin C treatment through the inactivation of bad-mediated apoptosis

Alcohol Metabolism Enriches Squamous Cell Carcinoma Cancer Stem Cells That Survive Oxidative Stress via Autophagy

BACKGROUND

Alcohol (ethanol) consumption is a major risk factor for head and neck and esophageal squamous cell carcinomas (SCCs). However, how ethanol (EtOH) affects SCC homeostasis is incompletely understood.

METHODS

We utilized three-dimensional (3D) organoids and xenograft tumor transplantation models to investigate how EtOH exposure influences intratumoral SCC cell populations including putative cancer stem cells defined by high CD44 expression (CD44H cells).

RESULTS

Using 3D organoids generated from SCC cell lines, patient-derived xenograft tumors, and patient biopsies, we found that EtOH is metabolized via alcohol dehydrogenases to induce oxidative stress associated with mitochondrial superoxide generation and mitochondrial depolarization, resulting in apoptosis of the majority of SCC cells within organoids. However, CD44H cells underwent autophagy to negate EtOH-induced mitochondrial dysfunction and apoptosis and were subsequently enriched in organoids and xenograft tumors when exposed to EtOH. Importantly, inhibition of autophagy increased EtOH-mediated apoptosis and reduced CD44H cell enrichment, xenograft tumor growth, and organoid formation rate.

CONCLUSIONS

This study provides mechanistic insights into how EtOH may influence SCC cells and establishes autophagy as a potential therapeutic target for the treatment of EtOH-associated SCC.

TIPE‑2 suppresses growth and aggressiveness of hepatocellular carcinoma cells through downregulation of the phosphoinositide 3‑kinase/AKT signaling pathway

Rapid proliferation and migration are the main features of hepatocellular carcinoma (HCC) cells, which serve an essential role in carcinogenesis and are a hallmark of cancer therapy resistance. Previous studies have reported that tumor necrosis factor-α-induced protein-8 like-2 (TIPE-2) is involved in cancer initiation and the progression of HCC. The present study aimed to clarify the role of TIPE-2 in HCC carcinogenesis, growth and aggressiveness. The effects of TIPE-2 on HCC were determined using colony forming and cell cycle analyses. Cell apoptosis, and growth and aggressiveness of HCC cells, were investigated following TIPE-2 treatment. Treatment with TIPE-2 markedly suppressed HCC cell proliferation and increased the number of cells in S phase of the cell cycle. The results demonstrated that TIPE-2 significantly inhibited growth, migration and invasion of HCC cells via the downregulation of tumor metastasis-associated genes. Flow cytometric analysis indicated that TIPE-2 promoted apoptosis of HCC cells via regulation of apoptosis-associated gene transcription. In addition, TIPE-2 administration downregulated the expression of phosphoinositide 3-kinase (PI3K) and protein kinase B (AKT) in HCC cells. In addition, TIPE-2 selectively decreased neuroblastoma Ras viral oncogene and p27 expression in HCC cells. In vivo assays revealed that TIPE-2 significantly inhibited tumor growth and prolonged animal survival by promoting apoptosis of tumor cells. The results of the present study indicated that TIPE-2 acts as an inhibitor of HCC cell growth and aggressiveness, and promotes apoptosis, thus suggesting that TIPE-2 may inhibit the metastasis-associated PI3K/AKT signaling cascade and may arrest the tumor cell cycle. These findings provide a potential molecular mechanism by which TIPE-2 promotes apoptosis of HCC cells.

Protein-protein interactions among signaling pathways may become new therapeutic targets in liver cancer (Review)

Numerous signaling pathways have been shown to be dysregulated in liver cancer. In addition, some protein-protein interactions are prerequisite for the uncontrolled activation or inhibition of these signaling pathways. For instance, in the PI3K/AKT signaling pathway, protein AKT binds with a number of proteins such as mTOR, FOXO1 and MDM2 to play an oncogenic role in liver cancer. The aim of the present review was to focus on a series of important protein-protein interactions that can serve as potential therapeutic targets in liver cancer among certain important pro-carcinogenic signaling pathways. The strategies of how to investigate and analyze the protein-protein interactions are also included in this review. A survey of these protein interactions may provide alternative therapeutic targets in liver cancer.

Long-term ethanol exposure-induced hepatocellular carcinoma cell migration and invasion through lysyl oxidase activation are attenuated by combined treatment with pterostilbene and curcumin analogues

Ethanol consumption induces hepatocellular carcinoma (HCC) cell metastasis by changing the extracellular matrix (ECM). Lysyl oxidase (LOX) catalyzes the cross-linkage of collagen or elastin in the ECM. LOX protein and mRNA overexpression (>21-fold compared with controls, n = 6) was detected in cirrhotic HCC patients with a history of alcoholism. LOX protein expression was induced in HCC cells after long-term treatment with ethanol (10 mM) for 20-40 passages (denoted E20-E40 cells). Pterostilbene (PSB, 1 μM) displayed significant potency to reduce LOX-mediated activity in E40 cells when combined with curcumin and its analogues. The ability of E40 cells to form colonies in soft agar was reduced by both genetic depletion of LOX and by chemical inhibitors of LOX expression. This study suggests that targeting LOX expression with food components such as PSB and curcumin may be a novel strategy to overcome ethanol-induced HCC cell metastasis in liver cancer patients.