Endoplasmic Reticulum Stress in Elderly Patients with COVID-19: Potential of Melatonin Treatment.

Aging processes, including immunosenescence, inflammation, inflammasome formation, genomic instability, telomeric attrition, and altered autophagy, are involved in viral infections and they may contribute to increased pathophysiological responses to the SARS-CoV-2 infection in the elderly; this poses additional risks of accelerated aging, which could be found even after recovery. Aging is associated with oxidative damage. Moreover, SARS-CoV-2 infections may increase the production of reactive oxygen species and such infections will disturb the Ca++ balance via an endoplasmic reticulum (ER) stress-mediated unfolded protein response. Although vaccine development and anti-inflammation therapy lower the severity of COVID-19, the prevalence and mortality rates are still alarming in some countries worldwide. In this review, we describe the involvement of viral proteins in activating ER stress transducers and their downstream signals and in inducing inflammation and inflammasome formation. Furthermore, we propose the potential of melatonin as an ER stress modulator, owing to its antioxidant, anti-inflammatory, and immunoregulatory effects in viral infections. Considering its strong safety profile, we suggest that additive melatonin supplementation in the elderly could be beneficial in treating COVID-19.

Anti-cancer therapeutic benefit of red guava extracts as a potential therapy in combination with doxorubicin or targeted therapy for triple-negative breast cancer cells.

Guava extracts purified from leaf and bark have many bio-active molecules with anti-cancer activities. In addition, lycopene-rich extracts obtained from red guava fruit can induce apoptosis in estrogen receptor-positive breast cancers. Triple-negative breast cancer (TNBC) lacks estrogen receptors, progesterone receptors and human epidermal growth factor receptor 2 (HER2) and, therefore, hormone therapy and targeted therapy are not used in the clinic. The purpose of this study was to determine whether red guava fruit extracts can affect the proliferation of TNBC cells. In this study, cell viability was determined by using the MTT assay. Apoptosis and necrosis were analyzed using flow cytometry. Cleaved caspase-3 and PARP were analyzed by western blotting. We found that red guava extracts can, through caspase-3 activation and PARP cleavage signaling, induce apoptotic and necrotic death in TNBC cells. Our results thus show the therapeutic benefit of red guava extracts as a potential cancer treatment for TNBC in combination with doxorubicin or targeted therapy.

Anti-Cancer Effects of Sulfasalazine and Vitamin E Succinate in MDA-MB 231 Triple-Negative Breast Cancer Cells.

Aim: Sulfasalazine (SSZ) displayed anti-cancer activities. Vitamin E succinate (VES) could inhibit cell growth in various cancer cells. However, chemical therapies were often not useful for triple-negative breast cancer cells (TNBCs) treatment. Here, this study investigated the anti-cancer effects and the mechanisms on TNBCs under combination treatment with SSZ and VES. Methods: Cell viability was analyzed by using the MTT assay. The H2O2 levels were determined by using lucigenin-amplified chemiluminescence method. In addition, caspase and MAPs signals were studied by using western blotting. Results: Low-dose VES antagonized the SSZ-induced cytotoxicity effects while high-dose VES promoted the SSZ-induced cytotoxicity effects on TNBCs. In addition, SSZ alone treatment activated both caspase-3 and ERK signals, however, VES alone treatment only activated JNK signals. On the other hand, activation of caspase-3, JNK, and ERK were found in SSZ plus VES-treated cells. Conclusion: Combined SSZ and VES has synergistic or antagonistic cytotoxic effects depending on VES concentration. In addition, different cytotoxic signals are induced on SSZ-treated, VES-treated and SSZ plus VES-treated cells.

Anticancer effects of methotrexate in combination with α­tocopherol and α­tocopherol succinate on triple­negative breast cancer.

Triple­negative breast cancers (TNBCs) lack the estrogen receptor, progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2). Therefore, hormone or targeted therapies are not effective in the treatment of TNBC and thus the development of novel therapeutic strategies is crucial. Methotrexate (MTX), a folate antagonist, has been used in the treatment of various types of cancer; however, the anticancer effects of MTX treatment on breast cancer have thus far been ineffective. Vitamin E variants and derivatives have been applied for cancer therapy. Previous studies have indicated that vitamin E variants and derivatives exert distinct anticancer effects on different types of cancer. However, whether MTX plus vitamin E variants or its derivatives can inhibit TNBC remains unclear. The aim of the present study was to examine the anticancer effects and mechanisms of action of MTX in combination with vitamin E variants (α­tocopherol) and derivatives (α­tocopherol succinate) on TNBC. In the present study, MTT assay and western blot analysis were used to determine the cell survival rates and protein levels. The results demonstrated that combination treatment with MTX and α­tocopherol suppressed TNBC cell proliferation. In addition, various concentrations of MTX exerted distinct cytotoxic effects on α­tocopherol succinate­treated cells. Furthermore, high­dose MTX enhanced α­tocopherol succinate­induced anticancer activity; however, low­dose MTX inhibited α­tocopherol succinate­induced anticancer activity. The present study also demonstrated that caspase­3 activation and poly(adenosine diphosphate­ribose) polymerase cleavage were observed in the α­tocopherol succinate/MTX­treated cells. In conclusion, the findings of the present study demonstrated that high­dose MTX enhanced anticancer activity in α­TOS­treated TNBC, while low­dose MTX reduced anticancer activity in α­TOS­treated TNBC.

Combined treatment with vitamin E and gefitinib has synergistic effects to inhibit TGF-ß1-induced renal fibroblast proliferation.

Renal fibroblast proliferation is key in renal fibrosis and chronic kidney disease. Transforming growth factor-ß1 (TGF-ß1) has been demonstrated to be an important factor that induces cell proliferation in renal fibroblasts. Epidermal growth factor receptor (EGFR) is also recognized as a factor promoting renal fibroblast proliferation. In addition, mitogen­activated protein kinase signaling pathways are associated with TGF­ß1­ and EGFR­induced cell proliferation. Gefitinib, an EGFR tyrosine kinase inhibitor, is predominantly used as an anti­tumor therapeutic agent in clinical therapeutic strategies. However, gefitinib has been suggested to exert anti­proliferative effects on renal fibroblasts, however, high­dose gefitinib may result in serious side effects. The present study aims to determine whether low­dose gefitinib reduces gefitinib­induced side effects and maintains the anti­proliferative effects on renal fibroblasts. TGF­ß1 promotes cell proliferation in renal fibroblasts, and the current study demonstrates that low­dose gefitinib treatment exhibits anti­proliferative effects similar to those of high­dose gefitinib treatment. Thus, although high­dose gefitinib is a conventional anti­tumor drug, low­dose gefitinib may be of use in renal fibrosis treatment. Furthermore, the present study demonstrates that a combined treatment with low-dose gefitinib and vitamin E has synergistic effects that reduce TGF­ß1­induced fibroblast proliferation, cell-cycle arrest and the ERK phosphorylation pathway.

Ascorbic acid inhibits TPA-induced HL-60 cell differentiation by decreasing cellular H2O2 and ERK phosphorylation.

Retinoic acid (RA), vitamin D and 12-O­tetradecanoyl phorbol-13-acetate (TPA) can induce HL-60 cells to differentiate into granulocytes, monocytes and macrophages, respectively. Similar to RA and vitamin D, ascorbic acid also belongs to the vitamin family. High­dose ascorbic acid (>100 µM) induces HL­60 cell apoptosis and induces a small fraction of HL­60 cells to express the granulocyte marker, CD66b. In addition, ascorbic acid exerts an anti­oxidative stress function. Oxidative stress is required for HL­60 cell differentiation following treatment with TPA, however, the effect of ascorbic acid on HL­60 cell differentiation in combination with TPA treatment remains to be fully elucidated. The aim of the present study was to investigate the cellular effects of ascorbic acid treatment on TPA-differentiated HL-60 cells. TPA-differentiated HL-60 cells were used for this investigation, this study and the levels of cellular hydrogen peroxide (H2O2), caspase activity and ERK phosphorylation were determined following combined treatment with TPA and ascorbic acid. The results demonstrated that low­dose ascorbic acid (5 µM) reduced the cellular levels of H2O2 and inhibited the differentiation of HL­60 cells into macrophages following treatment with TPA. In addition, the results of the present study further demonstrated that low­dose ascorbic acid inactivates the ERK phosphorylation pathway, which inhibited HL­60 cell differentiation following treatment with TPA.

Acetaminophen induces JNK/p38 signaling and activates the caspase-9-3-dependent cell death pathway in human mesenchymal stem cells.

Acetaminophen (APAP) is a widely used analgesic and antipyretic drug. Generally, the therapeutic dose of APAP is clinically safe, however, high doses of APAP can cause acute liver and kidney injury. Therefore, the majority of previous studies have focussed on elucidating the mechanisms of APAP-induced hepatotoxicity and nephrotoxicity, in addition to examining ways to treat these conditions in clinical cases. However, few studies have reported APAP-induced intoxication in human stem cells. Stem cells are important in cell proliferation, differentiation and repair during human development, particularly during fetal and child development. At present, whether APAP causes cytotoxic effects in human stem cells remains to be elucidated, therefore, the present study aimed to investigate the cellular effects of APAP treatment in human stem cells. The results of the present study revealed that high-dose APAP induced more marked cytotoxic effects in human mesenchymal stem cells (hMSCs) than in renal tubular cells. In addition, increased levels of hydrogen peroxide (H2O2), phosphorylation of c-Jun N-terminal kinase and p38, and activation of caspase-9/-3 cascade were observed in the APAP-treated hMSCs. By contrast, antioxidants, including vitamin C reduced APAP-induced augmentations in H2O2 levels, but did not inhibit the APAP-induced cytotoxic effects in the hMSCs. These results suggested that high doses of APAP may cause serious damage towards hMSCs.

Vitamin C enhances anticancer activity in methotrexate­treated Hep3B hepatocellular carcinoma cells.

Methotrexate (MTX) has been widely used for rheumatoid arthritis therapy for a long time. MTX is also used as an anticancer drug for various tumors. However, many studies have shown that high-dose MTX treatment for cancer therapy may cause liver and renal damage. Alhough the mechanisms involved in MTX-induced liver and renal damage require further research, many studies have indicated that MTX-induced cytotoxicity is associated with increases in oxidative stress and caspase activation. In order to reduce MTX-induced side-effects and increase anticancer efficiency, currently, combination treatments of low-dose MTX and other anticancer drugs are considered and applied for various tumor treatments. The present study showed that MTX induces increases in H2O2 levels and caspase-9/-3 activation leading to cell death in hepatocellular carcinoma Hep3B cells. Importantly, this study is the first to demonstrate that vitamin C can efficiently aid low-dose MTX in inducing cell death in Hep3B cells. Therefore, the present study provides a possible powerful therapeutic method for tumors using a combined treatment of vitamin C and low-dose MTX.

RC-RNase-induced cell death in estrogen receptor positive breast tumors through down-regulation of Bcl-2 and estrogen receptor.

RC-RNase exerts anti-cancer effects on many tumors. However, the mechanisms by which RC-RNase induces cytotoxicity in different tumor cells are unclear. Currently, estrogen receptor (ER)-positive and negative breast tumors are treated with RC-RNase. Our data demonstrate that RC-RNase induces cell death on ER-positive but not on ER-negative breast tumors. This study also shows that down-regulation of ER and Bcl-2 is found on RC-RNase-treated ER-positive breast tumors. Additionally, Bcl-2 overxpression can prevent ER-positive breast tumors from cell death treated with RC-RNase. In summary, this study demonstrates that RC-RNase-induced cell death of ER-positive breast tumors is through regulation of ER and Bcl-2.