LRIG1 enhances chemosensitivity by modulating BCL-2 expression and receptor tyrosine kinase signaling in glioma cells

Transcriptomics, molecular docking, and cross-resistance profiling of nobiletin in cancer cells and synergistic interaction with doxorubicin upon SOX5 transfection

BACKGROUND

Nobiletin is a polymethoxylated flavone from citrus fruit peels. Among other bioactivities, it acts antioxidative, anti-inflammatory, neuroprotective, and cardiovascular-protective. Nobiletin exerts profound anticancer activity in vitro and in vivo but the underlying mechanisms are not well understood.

PURPOSE

The aim was to unravel the multiple modes of action against cancer cells by bioinformatic and transcriptomic techniques and their verification by molecular pharmacological methods.

METHODS

The in silico methods used were COMPARE analysis of transcriptomic data, signaling pathway analysis, transcription factor binding motif analysis in promoter sequences of target genes, and molecular docking. The in vitro methods used were resazurin assay, isobologram analysis, generation of stably SOX5-tranfected cells, and Western blotting.

RESULTS

Nobiletin was cytotoxic against a wide range of cell lines from different tumor types, including diverse phenotypes to established anticancer drugs (e.g., P-glycoprotein, ABCB5, p53, EGFR). Cross-resistance profiling with 83 standard anticancer drugs revealed a correlation to antihormonal anticancer drugs, which can be explained by the phytoestrogenic features of nobiletin. Transcriptomic analysis showed that the responsiveness of tumor cells was predictable by their specific mRNA expression profile. Nobiletin bound to the transcription factor SOX5 in silico. SOX5 conferred resistance to the control drug doxorubicin but collateral sensitivity to nobiletin in HEK293 cells transfected with a lentiviral GFP-tagged pLOCORF-SOX5 vector. The combination of nobiletin and doxorubicin synergistically killed HEK293-SOX5 cells in isobologram analyses, implying attractive new treatment options.

CONCLUSION

Nobiletin represents an interesting candidate for cancer therapy with broad-spectrum activity and multiple modes of action. The identification of novel targets (i.e., SOX5) may allow its use for targeted tumor therapy in individualized treatment protocols.

The Intestinal Redox System and Its Significance in Chemotherapy-Induced Intestinal Mucositis

Chemotherapy-induced intestinal mucositis (CIM) is a significant dose-limiting adverse reaction brought on by the cancer treatment. Multiple studies reported that reactive oxygen species (ROS) is rapidly produced during the initial stages of chemotherapy, when the drugs elicit direct damage to intestinal mucosal cells, which, in turn, results in necrosis, mitochondrial dysfunction, and ROS production. However, the mechanism behind the intestinal redox system-based induction of intestinal mucosal injury and necrosis of CIM is still undetermined. In this article, we summarized relevant information regarding the intestinal redox system, including the composition and regulation of redox enzymes, ROS generation, and its regulation in the intestine. We innovatively proposed the intestinal redox “Tai Chi” theory and revealed its significance in the pathogenesis of CIM. We also conducted an extensive review of the English language-based literatures involving oxidative stress (OS) and its involvement in the pathological mechanisms of CIM. From the date of inception till July 31, 2021, 51 related articles were selected. Based on our analysis of these articles, only five chemotherapeutic drugs, namely, MTX, 5-FU, cisplatin, CPT-11, and oxaliplatin were shown to trigger the ROS-based pathological mechanisms of CIM. We also discussed the redox system-mediated modulation of CIM pathogenesis via elaboration of the relationship between chemotherapeutic drugs and the redox system. It is our belief that this overview of the intestinal redox system and its role in CIM pathogenesis will greatly enhance research direction and improve CIM management in the future.

Study of the chemical structure of exopolysaccharide produced from streptomycete and its effect as an attenuate for antineoplastic drug 5-fluorouracil that induced gastrointestinal toxicity in rats

Chemotherapeutic medications, including 5 - fluorouracil (5FU), are the same old technique to most cancers and are associated with numerous peripheral toxicities. We investigated exopolysaccharide (EPSST) produced from the isolated streptomycete of the Mediterranean Sea for the capability to lower the severity of mucositis in vivo. The streptomycete was isolated from Mediterranean Sea sediment from the beaches of Port Said Governorates, Egypt and identified morphologically, physiologically, and biochemically and confirmed by molecularly 16S rDNA analysis. The EPSST was extracted from the supernatant of streptomycete by using 4 volumes chilled ethanol and then the functional groups, MW, and chemical evaluation have been detected via Fourier-transform infrared (FTIR), and high-performance liquid chromatography (HPLC). In addition, antioxidant activity was measured through the usage of 2, 2-diphenyl-1-picrylhydrazyl (DPPH). Thirty-two male rats (180-200 g) were randomly divided into a control group (normal saline), intraperitoneal injection of 5-fluorouracil (5-FU, 150 mg/kg), normal rats were treated with EPSST and 5-FU + EPSST group. These groups were continued up to the day of sacrifice (28 days post treatments). The isolated strain became recognized based totally on 16S rDNA sequence as Streptomyce sp. with accession number SAMN08349905. The chemical evaluations of EPSST were galacturonic, glucose, galactose, mannose, and arabinose with a relative ratio of 2.1: 1: 5.37: 1.62: 1.29 individually, with an average molecular weight (Mw) 9.687 × 10³ g/mol. Also, the EPSST contained uronic acid (16%) and sulfate (12.149%) and no protein was detected. EPSST inhibited the DPPH radical activity. The findings of this study propose that EPSST inhibits 5-FU-induced mucositis through adjustment of oxidative stress, apoptosis, inflammatory factors, activation of antioxidant enzymes. The clinical administration of EPSST may recover the chemotherapy-induced intestinal dysfunction, consequently increasing the clinical efficiency of chemotherapy. In addition, the administration of EPSST reduced 5-FU-induced histopathological incongruities such as neutrophil infiltration, loss of cellular integrity, and villus and crypt distortion. The clinical administration of EPSST may recover the chemotherapy-induced intestinal dysfunction, consequently increasing the clinical efficiency of chemotherapy.

Antineoplastic effect of pectic polysaccharides from green sweet pepper (Capsicum annuum) on mammary tumor cells in vivo and in vitro

The present study investigated the antineoplastic effects of pectic polysaccharides that were extracted from green sweet pepper (Capsicum annuum [CAP]) in the Ehrlich carcinoma in mice and in human mammary tumor lineages. After the subcutaneous inoculation of 2 × 10⁶ Ehrlich tumor cells, Female Swiss mice received 50, 100, or 150 mg/kg CAP or vehicle orally once daily or methotrexate (2.5 mg/kg, i.p., every 5 days) for 21 days. CAP dose-dependently reduced Ehrlich tumor growth. It also reduced the viability of MCF-7, MDA-MB-231, and MDA-MB-436 human mammary cell lineages. Treatment with CAP reduced the gene expression of vascular endothelial growth factor in vivo and in vitro, reduced vessel areas of the tumors, and induced necrosis in Ehrlich solid tumors. CAP treatment significantly increased Interleukin-6 in tumors. The antineoplastic effect of CAP appears to depend on the regulation of inflammation and angiogenesis. Further studies are encouraged to better understand the CAP potential for the treatment of breast tumors.

Silencing of aquaporin 5 inhibits the growth of A549 lung cancer cells in vitro and in vivo

The water channel protein aquaporin 5 (AQP5) is highly expressed in numerous tumors. However, its expression pattern and functions in lung cancer in humans remain unknown. In the present study, the role of AQP5 in the development of lung malignancies was examined. A short hairpin RNA construct targeting AQP5 mRNA was transfected into A549 cells to generate a lung cancer cell line in which AQP5 expression was stably silenced. In vitro and in vivo experiments were then performed to establish the effects of AQP5 on A549 cell apoptosis, proliferation and cell cycle progression. The results demonstrated that AQP5 silencing significantly inhibited the proliferation and promoted the apoptosis of A549 lung cancer cells in vitro and in vivo. In addition, it resulted in decreased activation of the extracellular signal-regulated kinase 1/2 signaling pathway in A549 cells, and reduced levels of the downstream proteins c‑Fos and phosphorylated cAMP response element-binding protein. Furthermore, inhibition of AQP5 expression effectively reduced the tumorigenicity of A549 cells in vivo. In conclusion, silencing of AQP5 suppressed the growth of A549 cells in vitro and in vivo, suggesting that it may serve as a therapeutic target in lung cancer.

Angelica polysaccharides inhibit the growth and promote the apoptosis of U251 glioma cells in vitro and in vivo

BACKGROUND

Angelica sinensis (Oliv) Diels (Apiaceae) is a traditional medicine that has been used for more than 2000 years in China. It exhibits various therapeutic effects including neuroprotective, anti-oxidant, anti-inflammatory, and immunomodulatory activities. Angelica polysaccharides (APs), bioactive constituents of Angelica have been shown to be responsible for these effects; however, the utility of APs for the treatment of glioma and their mechanism of action remain to be elucidated.

PURPOSE

In this study, we investigated the inhibitory effects of APs on a glioma cell line and their molecular mechanism of action.

STUDY DESIGN

U251 cells were utilized to confirm the effects of APs on glioma.

METHODS

The human glioblastoma cell line U251 was utilized for both in vitro and in vivo models, in which we tested the effects of APs. Flow cytometry, gene expression analysis, western blotting, and MTT assays were used to elucidate the effects of APs on cell proliferation, cell cycle, and apoptosis.

RESULTS

The results demonstrated that APs significantly inhibited the growth and proliferation of U251 cells and induced their apoptosis. Furthermore, APs effectively reduced the expression of several cell cycle regulators: cyclins D1, B, and E. The apoptosis suppressor protein Bcl-2 was also downregulated, and the expression of pro-apoptotic proteins Bax and cleaved-caspase-3 increased. Additionally, APs inhibited the transforming growth factor (TGF)-β signaling pathway and stimulated the expression of E-cadherin, thus prohibiting cell growth.

CONCLUSION

In conclusion, the results indicate that APs attenuate the tumorigenicity of glioma cells and promote their apoptosis by suppressing the TGF-β signaling pathway. The present study therefore provides evidence of the inhibitory effects of APs against glioma progression, and proposes their potential application as alternative therapeutic agents for glioma.

MicroRNA-590-3p enhances the radioresistance in glioblastoma cells by targeting LRIG1

microRNA (miR)-590 has been found to serve potential roles in cancer development; however, the expression and function of miR-590 in human gliomas remains to be elucidated. The present study aimed to investigate the expression of miR-590 in human glioma tissues and radioresistant human glioblastoma cells (U251R), and to determine the effect and related molecular mechanism of miR-590-3p on the radiosensitivity of U251R cells in vitro. The results from reverse transcription-quantitative polymerase chain reaction indicated that miR-590-3p was upregulated in human glioma tissues and radioresistant human glioblastoma cells, and that miR-590-3p expression was higher in high grade than in low grade gliomas. In vitro experiments revealed that the miR-590-3p inhibitor enhanced the radiosensitivity of U251R cells by suppressing cell viability, decreasing colony formation capacity and increasing cell apoptosis rate, as demonstrated by MTT, colony formation and flow cytometry analyses. A luciferase reporter assay demonstrated that leucine-rich repeats and immunoglobulin-like domains protein 1 (LRIG1) was a direct target of miR-590-3p. Furthermore, it was demonstrated that the effect of miR-590-3p suppression on cell viability, colony formation capacity and cell apoptosis rate was attenuated by the knockdown of LRIG1 in the U251R cells. In conclusion, the present study revealed that miR-590-3p was upregulated in human glioma tissues and radioresistant human glioblastoma cells, and miR-590-3p contributes to the radioresistance of human glioblastoma cells by directly targeting LRIG1. These findings may provide potential therapeutic strategies to prevent radioresistance in human gliomas.

DNMT1 mediates chemosensitivity by reducing methylation of miRNA-20a promoter in glioma cells

Although methyltransferase has been recognized as a major element that governs the epigenetic regulation of the genome during temozolomide (TMZ) chemotherapy in glioblastoma multiforme (GBM) patients, its regulatory effect on glioblastoma chemoresistance has not been well defined. This study investigated whether DNA methyltransferase (DNMT) expression was associated with TMZ sensitivity in glioma cells and elucidated the underlying mechanism. DNMT expression was analyzed by western blotting. miR-20a promoter methylation was evaluated by methylation-specific PCR. Cell viability and apoptosis were assessed using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) and TdT-mediated dUTP-biotin nick end labeling assays, respectively. The results showed that compared with parental U251 cells, DNMT1 expression was downregulated, miR-20a promoter methylation was attenuated and miR-20a levels were elevated in TMZ-resistant U251 cells. Methyltransferase inhibition by 5-aza-2′-deoxycytidine treatment reduced TMZ sensitivity in U251 cells. In U251/TM cells, DNMT1 expression was negatively correlated with miR-20a expression and positively correlated with TMZ sensitivity and leucine-rich repeats and immunoglobulin-like domains 1 expression; these effects were reversed by changes in miR-20a expression. DNMT1 overexpression induced an increase in U251/TM cell apoptosis that was inhibited by the miR-20a mimic, whereas DNMT1 silencing attenuated U251/TM cell apoptosis in a manner that was abrogated by miR-20a inhibitor treatment. Tumor growth of the U251/TM xenograft was inhibited by pcDNA-DNMT1 pretreatment and boosted by DNMT1-small hairpin RNA pretreatment. In summary, DNMT1 mediated chemosensitivity by reducing methylation of the microRNA-20a promoter in glioma cells.

Adenovirus-mediated LRIG1 expression enhances the chemosensitivity of bladder cancer cells to cisplatin

Cisplatin (cis-diaminodichloroplatinum, CDDP) is one of the most effective chemotherapeutic agents that has been widely used in the treatment of many malignancies, including muscle invasive bladder cancer. However, development of CDDP resistance in cancer cells is a major obstacle to the effective treatment of bladder cancer. Therefore, the development of chemosensitizers to overcome the acquired resistance to chemotherapeutic agents is crucial. Previous studies have confirmed that the epidermal growth factor receptor (EGFR) and its signaling pathways are important in the chemoresistance of cancer cells against CDDP‑induced cell apoptosis. In a preliminary study we showed that leucine-rich repeats and immunoglobulin-like domains 1 (LRIG1) is the natural ligand of EGFR, and that the extracellular leucine-rich repeat (LRR) domain and immunoglobulin-like domains of LRIG1 were able to bind to the extracellular domain of EGFR, resulting in the downregulation of EGFR expression. Based on these findings, we hypothesized that LRIG1 may enhance the chemosensitivity of bladder cancer cells to CDDP. In the present study, LRIG1 was overexpressed by the adenovirus vector to determine the effect of LRIG1 on chemosensitivity in the T24 bladder cancer cell line and explored the possible mechanisms. The results showed that CDDP inhibited the growth of the T24 cell line and induced activation of EGFR. Overexpression of LRIG1 increased the inhibitory effect of CDDP on the T24 cell line, which may be associated with inactivation of the EGFR signaling pathway, followed by the decrease of Bcl-2 expression and a concomitantly induced expression of Bax. Based on these results, we concluded that the upregulation of LRIG1 expression inhibited the EGFR signaling pathway, activated the mitochondrial pathway of apoptosis and eventually increased the sensitivity of bladder cancer cells to CDDP.