The survival benefits of patients with glioblastoma (GBM) remain unsatisfactory due to the intrinsic or acquired resistance to temozolomide (TMZ). We elucidated the mechanisms of sulforaphane (SFN) reverse TMZ resistance in TMZ-inducing cell lines by inhibiting nuclear factor-κB (NF-κB) transcriptional activity. TMZ-resistant cell lines (U87-R and U373-R) were generated by stepwise (6 months) exposure of parental cells to TMZ. Luciferase reporter assay, biochemical assays and subcutaneous tumor establishment were used to characterize the antitumor effect of SFN. MGMT expression and 50% inhibiting concentration (IC50) values of TMZ in GBM cell lines were assessed. Next, we established that U87-R and U373-R cells presenting high IC50 of TMZ, activated NF-κB transcription and significantly increased MGMT expression compared with untreated cells. Furthermore, we revealed that SFN could significantly suppress proliferation of TMZ-resistant GBM cells. In addition, SFN effectively inhibited activity of NF-κB signaling pathway and then reduced MGMT expression to reverse the chemo-resistance to TMZ in T98G, U87-R and U373-R cell lines. Sequential combination with TMZ synergistically inhibited survival capability and increased the induction of apoptosis in TMZ-resistant GBM cells. Finally, a nude mouse model was established with U373-R cell subcutaneous tumor-bearing mice, and results showed that SFN could remarkably suppress cell growth and enhance cell death in chemo-resistant xenografts in the nude mouse model. Collectively, the present study suggests that the clinical efficacy of TMZ-based chemotherapy in TMZ-resistant GBM may be improved by combination with SFN.

/pdf/sulforaphane-reverses-chemo-resistance-to-temozolomide-in-3s6ock6dep.pdf

Sulforaphane reverses chemo-resistance to temozolomide in glioblastoma cells by NF-κB-dependent pathway downregulating MGMT expression.

Temozolomide (TMZ) is the standard of care chemotherapeutic agent used in the treatment of glioblastoma multiforme. Cytotoxic O6-methylguaine lesions formed by TMZ are repaired by O6-methyl-guanine DNA methyltransferase (MGMT), a DNA repair protein that removes alkyl groups located at the O6-position of guanine. Response to TMZ requires low MGMT expression and functional mismatch repair. Resistance to TMZ conferred by MGMT, and tolerance to O6-methylguanine lesions conferred by deficient MMR severely limit TMZ clinical applications. Therefore, development of new TMZ derivatives that can overcome TMZ-resistance is urgent. In this study, we investigated the anti-tumor mechanism of action of two novel TMZ analogs: C8-imidazolyl (377) and C8-methylimidazole (465) tetrazines. We found that analogs 377 and 465 display good anticancer activity against MGMT-overexpressing glioma T98G and MMR deficient colorectal carcinoma HCT116 cell lines with IC50 value of 62.50, 44.23, 33.09, and 25.37 μM, respectively. Analogs induce cell cycle arrest at G2/M, DNA double strand break damage and apoptosis irrespective of MGMT and MMR status. It was established that analog 377, similar to TMZ, is able to ring-open and hydrolyze under physiological conditions, and its intermediate product is more stable than MTIC. Moreover, DNA adducts of 377 with calf thymus DNA were identified: N7-methylguanine, O6-methylguanine, N3-methyladenine, N3-methylthymine, and N3-methylcytidine deoxynucleotides. We conclude that C8 analogs of TMZ share a mechanism of action similar to TMZ and are able to methylate DNA generating O6-methylguanine adducts, but unlike TMZ are able at least in part to thwart MGMT- and MMR-mediated resistance.

/pdf/c8-substituted-imidazotetrazine-analogs-overcome-2c5l906g5x.pdf

C8-Substituted Imidazotetrazine Analogs Overcome Temozolomide Resistance by Inducing DNA Adducts and DNA Damage.

Glioblastoma is the most common and aggressive primary malignant brain tumor. Temozolomide (TMZ), a chemotherapeutic agent combined with radiation therapy, is used as a standard treatment. The infiltrative nature of glioblastoma, however, interrupts effective treatment with TMZ and increases the tendency to relapse. Voltage-gated chloride channels have been identified as crucial regulators of glioma cell migration and invasion by mediating cell shape and volume change. Accordingly, chloride current inhibition by 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB), a chloride channel blocker, suppresses cell movement by diminishing the osmotic cell volume regulation. In this study, we developed a novel compound, TMZ conjugated with NPPB (TMZ-NPPB), as a potential anticancer drug. TMZ-NPPB blocked chloride currents in U373MG, a severely invasive human glioma cell line, and suppressed migration and invasion of U373MG cells. Moreover, TMZ-NPPB exhibited DNA modification activity similar to that of TMZ, and surprisingly showed remarkably enhanced cytotoxicity relative to TMZ by inducing apoptotic cell death via DNA damage. These findings indicate that TMZ-NPPB has a dual function in blocking both proliferation and migration of human glioma cells, thereby suggesting its potential to overcome challenges in current glioblastoma therapy.

Double Blockade of Glioma Cell Proliferation and Migration by Temozolomide Conjugated with NPPB, a Chloride Channel Blocker.

Background Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused the recent global COVID-19 outbreak, which led to a public health emergency. Entry of SARS-CoV-2 into human cells is dependent on the SARS-CoV receptor, angiotensin converting enzyme 2 (ACE2) receptor, and cathepsin. Cathepsin degrades the spike protein (S protein), which results in the entry of viral nucleic acid into the human host cell. Methods We explored the susceptibility of the central nervous system (CNS) to SARS-CoV-2 infection using single-cell transcriptome analysis of glioblastoma. Results The results showed that ACE2 expression is relatively high in endothelial cells (ECs), bone marrow mesenchymal stem cells (BMSCs), and neural precursor cells (NPCs). Cathepsin B (Cat B) and cathepsin (Cat L) were also strongly expressed in various cell clusters within the glioblastoma microenvironment. Immunofluorescence staining of glioma and normal brain tissue chips further confirmed that ACE2 expression co-localized with CD31, CD73, and nestin, which confirmed the susceptibility to SARS-CoV-2 of nervous system cells, including ECs, BMSCs, and NPCs, from clinical specimens. Conclusions These findings reveal the mechanism of SARS-CoV-2 neural invasion and suggest that special attention should be paid to SARS-CoV-2-infected patients with neural symptoms, especially those who suffered a glioma.

/pdf/single-cell-sequencing-of-glioblastoma-reveals-central-2i62osao23.pdf

Single-Cell Sequencing of Glioblastoma Reveals Central Nervous System Susceptibility to SARS-CoV-2

Background Existence of acquired or intrinsic resistance to Temozolomide (TMD) remains a point of concern in treating glioblastoma (GBM). Here we established mechanism by which Phenethyl isothiocyanate (PEITC) reverses TMD resistance in T98G cell lines both in vitro and in vivo. Methods For the study TMD-resistant cell lines were generated by stepwise exposing the parental cell lines (U87 and U373) to TMD. The 50% inhibitory concentration (IC50) values were established. MTT assay was done for cell survival studies, apoptosis assay by FITC Annexin V/PI staining, luciferase reporter assay for NF-κB transcription activity, cell colony survival and cell invasion assay, protein expression by western blot was done. For in vivo studies nude mouse model of GBM was established, TUNEL assay was done for apoptosis in tumor specimens. Results We established that T98G, U87-R and U373-R showed higher NF-κB activity and exhibited higher IC50 of TMD with significantly increased MGMT expression compared to untreated cells. Next, we found that PEITC suppressed proliferation of resistant GBM cells, inhibited NF-κB activity, decreased expression of MGMT and reversed the resistance in U373-R, U87-R and T98G cells. Exposure to PEITC followed by sequential treatment of TMD produced synergistic effect. In U373-R grafted xenografts mouse model PEITC suppressed cell growth and enhanced cell death. Conclusion Altogether, the present research established that combination of PEITC with TMD could enhance its clinical efficacy in resistant GBM by suppressing MGMT via inhibiting NF-κB activity.

Sequential treatment of phenethyl isothiocyanate increases sensitivity of Temozolomide resistant glioblastoma cells by decreasing expression of MGMT via NF-κB pathway.

The aim of this study is to investigate the inhibitory effects of 2T-P400, a derivative of temozolomide (TMZ), on glioma growth. SHG-44 and U373 human glioblastoma cell lines and SHG-44 cell subcutaneous and intracranial xenograft mouse models were used as the model system for these studies. Cell growth was analyzed using MTT assay. For intracranial glioma xenograft model, mouse brains were obtained and made as paraffin section for immunohistochemical staining. Tumor volume was calculated with this formula: tumor volume = length × width2/ 2. The results showed that 2T-P400 or TMZ significantly inhibits cell growth in a concentration dependent manner with the IC50 values of 12.90 ± 1.05 or 9.73 ± 2.12 μg/ml on SHG-44 cell line and 13.12 ± 0.86 or 10.13 ± 1.02 μg/ml on U373 cell line respectively. In SHG-44 cell subcutaneous xenograft model, the tumor volume of 2T-P400 or TMZ treated group was 1,062.12 ± 204.76 or 803.59 ± 110.32 mm3 respectively, which was significantly smaller than that in physiological saline (with volume of 1,968.85 ± 348.37 mm3) treated group. In intracranial xenograft model, the tumor volume of 2T-P400 or TMZ group was 6.12 ± 1.69 or 5.58 ± 1.45 mm3 respectively, significantly smaller than that in physiological saline group of 33.08 ± 6.88 mm3. Moreover, polyethylene glycol 400 (PEG400) exhibited no significant tumor growth inhibition. Our results indicated that 2T-P400 posses the same growth inhibitory effect as TMZ on glioblastoma cell lines and the subcutaneously and intracranially transplanted gliomas in xenograft mouse models. It may be a suitable alternate of TMZ for the treatment of glioma via intravenous administration route.

The temozolomide derivative 2T-P400 inhibits glioma growth via administration route of intravenous injection

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Ling Wang

Author Tools

Chat about Author

Papers

The temozolomide derivative 2T-P400 inhibits glioma growth via administration route of intravenous injection