Questiomycin A stimulates sorafenib-induced cell death via suppression of glucose-regulated protein 78

Decoding the roles of heat shock proteins in liver cancer

Hepatocellular carcinoma (HCC) is one of the most common gastrointestinal malignancies, characterized by insidious onset and high propensity for metastasis and recurrence. Apart from surgical resection, there are no effective curative methods for HCC in recent years, due to resistance to radiotherapy and chemotherapy. Heat shock proteins (HSP) play a crucial role in maintaining cellular homeostasis and normal organism development as molecular chaperones for intracellular proteins. Both basic research and clinical data have shown that HSPs are crucial participants in the HCC microenvironment, as well as the occurrence, development, metastasis, and resistance to radiotherapy and chemotherapy in various malignancies, particularly liver cancer. This review aims to discuss the molecular mechanisms and potential clinical value of HSPs in HCC, which may provide new insights for HSP-based therapeutic interventions for HCC.

UDP-glucose 6-dehydrogenase lessens sorafenib sensitivity via modulating unfolded protein response

As the first-generation targeted therapy, sorafenib remains an effective single-drug treatment for advanced hepatocellular carcinoma (HCC). Unfortunately, the existence of resistance restricts the long-term benefit of patients. UDP-glucose 6-dehydrogenase (UGDH) is the key enzyme of glucuronic acid metabolism which was largely reported in mediating drug systemic elimination. In this study, we explore its critical role in regulating sorafenib sensitivity. Here we find sorafenib exposure could activate glucuronic acid metabolism, accompanied with the elevated expression of UGDH. Interference with the route by silencing UGDH could boost HCC cells sensitivity to sorafenib. Meanwhile, the analysis of HCC patients with sorafenib treatment displayed that low UGDH expression predicted superior prognosis. Further screening assay suggested that unfolded protein response (UPR) involves in UGDH silencing-mediated apoptosis. Xenograft model confirmed that combined UGDH intervention could significantly improve sorafenib efficacy. Our results reveal the impact of sorafenib exposure on glucuronic acid metabolism reprogramming and provide UGDH as a promising target to improve sorafenib efficacy.

The natural occurrence of Penicillium spp. metabolites in maize kernels originating from Serbia

Maize can be contaminated with a wide range of fungal secondary metabolites that decrease the quality and safety of maize and maize-derived products. The increase of natural fungal metabolites occurrence in maize, influenced by climate changes, is recognized as a significant issue in recent years. Therefore, the main aim of this study was to investigate the influence of weather conditions on the natural occurrence of Penicillium spp. metabolites in maize kernel samples. The survey was conducted for two maize vegetation seasons 2016 and 2017. In total 458 maize samples were analyzed by liquid chromatography-tandem mass spectrometry method. The samples originated from the Autonomous Province of Vojvodina, and regions of Bačka, Srem, and Banat. Among 45 Penicillium metabolites investigated 16 and 18 were detected in samples from 2016 and 2017, respectively. The most commonly occurring Penicillium metabolite in both years was oxaline, which was detected in more than 90% of analyzed samples. Questiomycin A, 7hydroxypestalotin, pestalotin, and mycophenolic acid were also very frequently detected Penicillium metabolites. This is one of the unique studies in the Republic of Serbia, as well as in this part of Europe, investigating the occurrence of a great number of Penicillium metabolites in maize samples.

The natural occurrence of Penicillium spp. metabolites in maize kernels originating from Serbia

Maize can be contaminated with a wide range of fungal secondary metabolites that decrease the quality and safety of maize and maize-derived products. The increase of natural fungal metabolites occurrence in maize, influenced by climate changes, is recognized as a significant issue in recent years. Therefore, the main aim of this study was to investigate the influence of weather conditions on the natural occurrence of Penicillium spp. metabolites in maize kernel samples. The survey was conducted for two maize vegetation seasons 2016 and 2017. In total 458 maize samples were analyzed by liquid chromatography-tandem mass spectrometry method. The samples originated from the Autonomous Province of Vojvodina, and regions of Bačka, Srem, and Banat. Among 45 Penicillium metabolites investigated 16 and 18 were detected in samples from 2016 and 2017, respectively. The most commonly occurring Penicillium metabolite in both years was oxaline, which was detected in more than 90% of analyzed samples. Questiomycin A, 7hydroxypestalotin, pestalotin, and mycophenolic acid were also very frequently detected Penicillium metabolites. This is one of the unique studies in the Republic of Serbia, as well as in this part of Europe, investigating the occurrence of a great number of Penicillium metabolites in maize samples.

Endoplasmic reticulum stress: Multiple regulatory roles in hepatocellular carcinoma

BACKGROUND

Endoplasmic reticulum (ER) stress is a basic cellular stress response that maintains cellular protein homeostasis under endogenous or exogenous stimuli, which depends on the stimulus, its intensity, and action time. The ER produces a corresponding cascade reaction for crosstalk of adaptive and/or pro-death regulation with other organelles. Hepatocellular carcinoma(HCC) is one of the most common malignant solid tumors with an extremely poor prognosis. Viral hepatitis infection, cirrhosis, and steatohepatitis are closely related to the occurrence and development of HCC, and ER stress has gradually been shown to be a major mechanism. Moreover, an increasing need for protein and lipid products and relative deficiencies of oxygen and nutrients for rapid proliferation and endoplasmic reticulum stress are undoubtedly involved. Therefore, to fully and comprehensively understand the regulatory role of endoplasmic reticulum stress in the occurrence and progression of HCC is of vital importance to explore its pathogenesis and develop novel anti-cancer strategies.

METHODOLOGY

We searched for relevant publications in the PubMed databases using the keywords "Endoplasmic reticulum stress", "hepatocellular carcinoma" in last five years,and present an overview of the current knowledge that links ER stress and HCC, which includes carcinogenesis, progression, and anti-cancer strategies, and propose directions of future research.

RESULT

ER stress were confirmed to be multiple regulators or effectors of cancer, which also be confirmed to drive tumorigenesis and progression of HCC. Targeting ER stress signaling pathway and related molecules could play a critical role for anti-HCC and has become a research hotspot for anti-cancer in recent years.

CONCLUSION

ER stress are critical for the processes of the tumorigenesis and progression of tumors. For HCC, ER stress was associated with tumorigenesis, development, metastasis, angiogenesis and drug resistance, targeting ER stress has emerged as a potential anti-tumor strategy.

Pharmacological Activities of Aminophenoxazinones

Aminophenoxazinones are degradation products resulting from the metabolism of different plant species, which comprise a family of natural products well known for their pharmacological activities. This review provides an overview of the pharmacological properties and applications proved by these compounds and their structural derivatives during 2000-2021. The bibliography was selected according to our purpose from the references obtained in a SciFinder database search for the Phx-3 structure (the base molecule of the aminophenoxazinones). Compounds Phx-1 and Phx-3 are among the most studied, especially as anticancer drugs for the treatment of gastric and colon cancer, glioblastoma and melanoma, among others types of relevant cancers. The main information available in the literature about their mechanisms is also described. Similarly, antibacterial, antifungal, antiviral and antiparasitic activities are presented, including species related directly or indirectly to significant diseases. Therefore, we present diverse compounds based on aminophenoxazinones with high potential as drugs, considering their levels of activity and few adverse effects.

PERK/ATF4-Dependent ZFAS1 Upregulation Is Associated with Sorafenib Resistance in Hepatocellular Carcinoma Cells

Sorafenib, a multi-kinase inhibitor, is the first-line treatment for advanced hepatocellular carcinoma (HCC) patients. However, this drug only provides a short improvement of patients' overall survival, and drug resistance is commonly developed. Thus, the identification of resistant factor(s) or biomarker(s) is needed to develop more efficient therapeutic strategies. Long, non-coding RNAs (lncRNAs) have recently been viewed as attractive cancer biomarkers and drive many important cancer phenotypes. A lncRNA, ZFAS1 (ZNFX1 antisense RNA 1) has been found to promote HCC metastasis. This study found that sorafenib induced ZFAS1 expression specifically in sorafenib-resistant HCC cells. Although ZFAS1 knockdown did not restore the sensitivity of HCC cells to sorafenib, its expression may act as a resistant biomarker for sorafenib therapy. Bioinformatics analysis predicted that sorafenib tended to induce pathways related to endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) in sorafenib-resistant HCC cells. In vitro experimental evidence suggested that sorafenib induced protein kinase RNA-like ER kinase (PERK)/activating transcription factor 4 (ATF4)-dependent ZFAS1 expression, and sorafenib resistance could be overcome by PERK/ATF inhibitors. Therefore, PERK/ATF4/ZFAS1 signaling axis might be an attractive therapeutic and prognostic biomarker for sorafenib therapy in HCC.

Bacteria and bacterial anticancer agents as a promising alternative for cancer therapeutics

Cancer is the leading cause of deaths worldwide, though significant advances have occurred in its diagnosis and treatment. The development of resistance against chemotherapeutic agents, their side effects, and non-specific toxicity urge to screen for the novel anticancer agent. Hence, the development of novel anticancer agents with a new mechanism of action has become a major scientific challenge. Bacteria and bacterially produced bioactive compounds have recently emerged as a promising alternative for cancer therapeutics. Bacterial anticancer agents such as antibiotics, bacteriocins, non-ribosomal peptides, polyketides, toxins, etc. These are adopted different mechanisms of actions such as apoptosis, necrosis, reduced angiogenesis, inhibition of translation and splicing, and obstructing essential signaling pathways to kill cancer cells. Also, live tumor-targeting bacteria provided a unique therapeutic alternative for cancer treatment. This review summarizes the anticancer properties and mechanism of actions of the anticancer agents of bacterial origin and antitumor bacteria along with their possible future applications in cancer therapeutics.

GRP78 and next generation cancer hallmarks: An underexplored molecular target in cancer chemoprevention research

Glucose regulated protein 78 (GRP 78), a master regulator of endoplasmic reticulum stress has been reported to be up regulated in various cancers and remains a crucial link between tumor glycolysis and tumor microenvironment. Overexpressed GRP78 has also shown to induce immune suppressive molecules and thereby tumor immune evasion. On the other hand emerging reports indicates that the next generation hallmarks viz., metabolic reprogramming and immune evasion, the two distinct processes are suggested to be fundamentally linked which is yet to be explored. Our concern is, if GRP78 is considered as a connecting link between these two different processes then targeting this triangle would be a promising approach in anticancer drug discovery. Lack of sufficient literature on this aspect represents GRP78 as an under explored target in anti-cancer research. The objective of this review is to provide a concise and integrated information on GRP78 and its association with tumor glycolysis and immune evasion which will revive and draw attention of the researchers to consider GRP78 as a potential drug target for cancer intervention and it also highlights few potential natural products investigated so far as GRP78 inhibitors.

Kuanoniamine C stimulates bortezomib-induced cell death via suppression of glucose-regulated protein 78 in osteosarcoma

Osteosarcoma is the most frequent and intractable malignancy of the bone in children and young adults. Surgical operation requires extensive excision of the cancer tissue and neighboring normal tissues. In addition, anticancer drugs and radiation therapy are thought to be almost ineffective. Glucose-regulated protein 78 (GRP78), a cell-protective endoplasmic reticulum (ER) chaperone protein, is one of the most promising anticancer targets for osteosarcoma. Here, by analyzing the molecular mechanisms of kuanoniamine C, we report that kuanoniamine C suppresses GRP78 expression via GRP78 mRNA degradation in an ER stress response-independent manner. Interestingly, kuanoniamine C-induced cell death and downregulation of GRP78 expression was regulated by p53 signaling. Moreover, co-treatment with bortezomib, which is a newly identified anticancer drug for osteosarcoma, and kuanoniamine C suppressed GRP78 protein expression, which is essential for the stimulation of bortezomib-induced cell death. These results suggest that co-treatment with bortezomib and kuanoniamine C is a novel therapeutic strategy for the treatment of osteosarcoma that enhances bortezomib-dependent cell death by the downregulation of GRP78, and this combination selectively targets the major cell population of osteosarcoma, which expresses wild-type p53.

Proteomic Profile of Sorafenib Resistance in Hepatocellular Carcinoma; GRP78 Expression Is Associated With Inferior Response to Sorafenib

BACKGROUND/AIM

The outcome of patients with advanced hepatocellular carcinoma (HCC) remains poor and therapeutic options, including sorafenib, the first anti-cancer drug proved to prolong survival in patients with advanced HCC, are limited. However, no clinically useful predictive biomarker for sorafenib has been reported.

MATERIALS AND METHODS

We exploited two-dimensional gel electrophoresis coupled with mass spectrometry to find de-regulated proteins by using conditioning of a sorafenib-resistant HCC cell line, Huh7. Tumor samples from 60 patients with HCC treated with sorafenib were analyzed and correlated with survival outcome.

RESULTS

Comparative proteomics indicated three proteins including, 78 kDa glucose related protein (GRP78), 14-3-3ε, and heat shock protein 90β (HSP90β). The three proteins were over-expressed in sorafenib-resistant Huh7 cells. In HCC tumor samples from patients treated with sorafenib, 73% of tumor samples had a high expression of GRP78, 18% had high 14-3-3ε expression and 85% had high HSP90β expression. Among these, GRP78 was associated with the shortest progression-free survival of HCC patients treated with sorafenib.

CONCLUSION

GRP78 can be a predictive biomarker in HCC patients treated with sorafenib. Strategies designed to inhibit the GRP78-related pathway may overcome sorafenib resistance.

Pharmacological effectors of GRP78 chaperone in cancers

The protein chaperone GRP78 is a master regulator of endoplasmic reticulum (ER) functions and is frequently over-expressed at the surface of cancer cells where it contributes to chemo-resistance. It represents a well-studied ER stress marker but an under-explored target for new drug development. This review aims to untangle the structural and functional diversity of GRP78 modulators, covering over 130 natural products, synthetic molecules, specific peptides and monoclonal antibodies that target GRP78. Several approaches to promote or to incapacitate GRP78 are presented, including the use of oligonucleotides and specific cell-delivery peptides often conjugated to cytotoxic payloads to design GRP78-targeted therapeutics. A repertoire of drugs that turn on/off GRP78 is exposed, including molecules which bind directly to GRP78, principally to its ATP site. There exist many options to regulate positively or negatively the expression of the chaperone, or to interfere with its cellular trafficking. This review provides a molecular cartography of GRP78 pharmacological effectors and adds weight to the notion that GRP78 repressors could represent promising anticancer therapeutics, notably as regards limiting chemo-resistance of cancer cells. The potential of GRP78-targeting drugs in other therapeutic modalities is also evoked.