Augmenter of liver regeneration potentiates doxorubicin anticancer efficacy by reducing the expression of ABCB1 and ABCG2 in hepatocellular carcinoma

Mechanisms of drug resistance in breast cancer liver metastases: Dilemmas and opportunities

Breast cancer is the leading cause of cancer-related deaths in females worldwide, and the liver is one of the most common sites of distant metastases in breast cancer patients. Patients with breast cancer liver metastases face limited treatment options, and drug resistance is highly prevalent, leading to a poor prognosis and a short survival. Liver metastases respond extremely poorly to immunotherapy and have shown resistance to treatments such as chemotherapy and targeted therapies. Therefore, to develop and to optimize treatment strategies as well as to explore potential therapeutic approaches, it is crucial to understand the mechanisms of drug resistance in breast cancer liver metastases patients. In this review, we summarize recent advances in the research of drug resistance mechanisms in breast cancer liver metastases and discuss their therapeutic potential for improving patient prognoses and outcomes.

CASK Silence Overcomes Sorafenib Resistance of Hepatocellular Carcinoma Through Activating Apoptosis and Autophagic Cell Death

Hepatocellular carcinoma (HCC) patients usually fail to be treated because of drug resistance, including sorafenib. In this study, the effects of CASK in HCC were investigated using gain- or loss-of-function strategies by performing cell counting kit-8 assay, colony formation assay, flow cytometry, transmission electron microscopy, immunofluorescent confocal laser microscopy, tumor xenograft experiment and immunohistochemistry staining. The current results suggested that CASK expression was positively associated with sorafenib resistance and poor prognosis of HCC. Moreover, inhibition of CASK increased the role of sorafenib partially by promoting apoptosis and autophagy, while CASK overexpression presented the opposite effects. Besides, when treatment with sorafenib, inhibition of apoptosis using the pan-caspase inhibitor Z-VAD-FMK and inhibition of autophagy using autophagy inhibitor 3-Methyladenine (3-MA) or small interfering RNA (siRNA) of LC3B all significantly reversed CASK knockout-induced effects, suggesting that both apoptosis and autophagy were involved in CASK-mediated above functions and autophagy played a pro-death role in this research. Intriguingly, similar results were observed in vivo. In molecular level, CASK knockout activated the c-Jun N-terminal kinase (JNK) pathway, and treatment with JNK inhibitor SP600125 or transiently transfected with siRNA targeting JNK significantly attenuated CASK knockout-mediated autophagic cell death. Collectively, all these results together indicated that CASK might be a promising biomarker and a potential therapeutic target for HCC patients.

ACTL6A knockdown inhibits cell migration by suppressing the AKT signaling pathway and enhances the sensitivity of glioma cells to temozolomide

Molecular-targeted therapy has had a significant impact on glioma. Notably, actin-like 6A (ACTL6A) has been indicated to be essential for embryonic development and tumor progression. However, the role of ACTL6A in glioma remains unclear. The present study aimed to investigate the effects of ACTL6A on glioma cell migration and sensitivity to temozolomide (TMZ). The expression levels of ACTL6A were analyzed in patients with glioma, and survival curves were created using data from The Cancer Genome Atlas. U251 and T98G cells were transfected with short hairpin (sh)RNA for use in loss-of-function experiments to investigate the biological function and molecular mechanisms of ACTL6A. Furthermore, an MTT assay was used to assess the effect of ACTL6A on the sensitivity of glioma cells to TMZ. The results demonstrated that ACTL6A was expressed at higher levels in glioma tissues compared with normal brain tissues. Furthermore, high expression of ACTL6A was associated with a poor prognosis. The knockdown of ACTL6A significantly inhibited the migration phenotype in glioma cells and significantly decreased the levels of phosphorylated AKT in glioma cells. The AKT signaling activator SC79 partly attenuated the inhibitory effects of ACTL6A shRNA on glioma cell migration. Additionally, the knockdown of ACTL6A enhanced the sensitivity of glioma cells to TMZ. In conclusion, these results suggest that ACTL6A knockdown inhibited the migration of human glioma cells, at least in part through inactivation of the AKT signaling pathway, and increased the sensitivity of glioma cells to TMZ. Therefore, ACTL6A may be a potential therapeutic target for glioma.

Role of breast cancer resistance protein in gastrointestinal tumors

The breast cancer resistance protein, also known as ABCG2, is a member of the drug efflux membrane transporters. As a drug discharge pump, ABCG2 can reduce the concentration of intracellular drugs and protect cells from toxic substances. ABCG2 is not only able to protect normal cells, but also to influence the chemotherapy effect by making tumor cells resistant to various anti-cancer drugs. In order to provide a reference for the basic and clinical research of gastrointestinal tumors, we review the physiological function of ABCG2, factors affecting ABCG2 expression, and its relationship with gastrointestinal tumors.

Augmenter of liver regeneration: Essential for growth and beyond

Liver regeneration is a well-orchestrated process that is triggered by tissue loss due to trauma or surgical resection and by hepatocellular death induced by toxins or viral infections. Due to the central role of the liver for body homeostasis, intensive research was conducted to identify factors that might contribute to hepatic growth and regeneration. Using a model of partial hepatectomy several factors including cytokines and growth factors that regulate this process were discovered. Among them, a protein was identified to specifically support liver regeneration and therefore was named ALR (Augmenter of Liver Regeneration). ALR protein is encoded by GFER (growth factor erv1-like) gene and can be regulated by various stimuli. ALR is expressed in different tissues in three isoforms which are associated with multiple functions: The long forms of ALR were found in the inner-mitochondrial space (IMS) and the cytosol. Mitochondrial ALR (23 kDa) was shown to cooperate with Mia40 to insure adequate protein folding during import into IMS. On the other hand short form ALR, located mainly in the cytosol, was attributed with anti-apoptotic and anti-oxidative properties as well as its inflammation and metabolism modulating effects. Although a considerable amount of work has been devoted to summarizing the knowledge on ALR, an investigation of ALR expression in different organs (location, subcellular localization) as well as delineation between the isoforms and function of ALR is still missing. This review provides a comprehensive evaluation of ALR structure and expression of different ALR isoforms. Furthermore, we highlight the functional role of endogenously expressed and exogenously applied ALR, as well as an analysis of the clinical importance of ALR, with emphasis on liver disease and in vivo models, as well as the consequences of mutations in the GFER gene.

Augmenter of Liver Regeneration Protects against Ethanol-Induced Acute Liver Injury by Promoting Autophagy

Alcoholic liver disease is associated with high morbidity and mortality, and treatment options are limited to date. Augmenter of liver regeneration (ALR) may protect against hepatic injury from chemical poisons, including ethanol. Autophagy appears to positively influence survival in cases of liver dysfunction, although the mechanisms are poorly understood. Herein, we investigated effects of ALR-induced autophagy in vitro and in vivo in an ethanol-induced model of acute liver injury. Decreased serum levels of alanine aminotransferase and aspartate aminotransferase and reduced histologic lesions revealed that mice overexpressing ALR experienced less liver damage than wild-type. ALR-knockdown mice experienced more severe liver damage than wild-type. ALR-transfected HepG2 cells showed increased survival rates, improved maintenance of mitochondrial membrane potential, and increased ATP levels after ethanol treatment. The observed protection was associated with up-regulation of autophagy-markers, including light chain 3II, beclin-1, and autophagy-related gene 5, and down-regulation of p62 by ALR. Autophagy was inhibited in ALR-knockdown mice and HepG2 cells, and autophagy inhibitor bafilomycin A1 attenuated the protective effects of ALR. Results showed phosphorylated mammalian target of rapamycin (mTOR) was down-regulated when ALR was overexpressed and up-regulated when ALR was knocked down. These data show that ALR is protective against ethanol-induced acute liver injury by promoting autophagy, probably via repressing the mTOR pathway. These results have potential implications for the clinical treatment of alcoholic liver disease patients.

Exosomes in the Oncobiology, Diagnosis, and Therapy of Hepatic Carcinoma: A New Player of an Old Game

Exosomes are emerging as essential vehicles mediated cross-talk between different types of cells in tumor microenvironment. The extensive exploration of exosomes in hepatocellular carcinoma (HCC) enhances our comprehension of cancer biology referring to tumor growth, metastasis, immune evasion, and chemoresistance. Besides, the versatile roles of exosomes provide reasonable explanations for the propensity for liver metastasis of gastric cancer, pancreatic ductal adenocarcinoma, breast cancer, and colorectal cancer. The selective-enriched components, especially some specific proteins and noncoding RNAs in exosomes, have great potential as noninvasive biomarkers of HCC with high sensitivity and specificity. The characteristics of exosomes further inspire frontier research to interrupt intercellular malignant signals by controlling the biogenesis, release, or contents of exosomes.