Temozolomide alleviates breast carcinoma via the inhibition of EGFR/ERK/ MMP-1 pathway with induction of apoptotic events.

PURPOSE: To evaluate the chemotherapeutic activity of temozolomide counter to mammary carcinoma. METHODS: In-vitro anticancer activity has been conducted on MCF7 cells, and mammary carcinoma has been induced in Wistar rats by introduction of 7, 12-Dimethylbenz(a)anthracene (DMBA), which was sustained for 24 weeks. Histopathology, immunohistochemistry, cell proliferation study and apoptosis assay via TUNEL method was conducted to evaluate an antineoplastic activity of temozolomide in rat breast tissue. RESULTS: IC50 value of temozolomide in MCF7 cell has been obtained as 103 µM, which demonstrated an initiation of apoptosis. The temozolomide treatment facilitated cell cycle arrest in G2/M and S phase dose dependently. The treatment with temozolomide suggested decrease of the hyperplastic abrasions and renovation of the typical histological features of mammary tissue. Moreover, temozolomide therapy caused the downregulation of epidermal growth factor receptor, extracellular signal-regulated kinase, and metalloproteinase-1 expression and upstream of p53 and caspase-3 proliferation to indicate an initiation of apoptotic events. CONCLUSIONS: The occurrence of mammary carcinoma has been significantly decreased by activation of apoptotic pathway and abrogation of cellular propagation that allowable for developing a suitable mechanistic pathway of temozolomide in order to facilitate chemotherapeutic approach.

Dual-targeted delivery of temozolomide by multi-responsive nanoplatform via tumor microenvironment modulation for overcoming drug resistance to treat glioblastoma.

Glioblastoma (GBM) is the most aggressive primary brain tumor with low survival rate. Currently, temozolomide (TMZ) is the first-line drug for GBM treatment of which efficacy is unfortunately hindered by short circulation time and drug resistance associated to hypoxia and redox tumor microenvironment. Herein, a dual-targeted and multi-responsive nanoplatform is developed by loading TMZ in hollow manganese dioxide nanoparticles functionalized by polydopamine and targeting ligands RAP12 for photothermal and receptor-mediated dual-targeted delivery, respectively. After accumulated in GBM tumor site, the nanoplatform could respond to tumor microenvironment and simultaneously release manganese ion (Mn2+), oxygen (O2) and TMZ. The hypoxia alleviation via O2 production, the redox balance disruption via glutathione consumption and the reactive oxygen species generation, together would down-regulate the expression of O6-methylguanine-DNA methyltransferase under TMZ medication, which is considered as the key to drug resistance. These strategies could synergistically alleviate hypoxia microenvironment and overcome TMZ resistance, further enhancing the anti-tumor effect of chemotherapy/chemodynamic therapy against GBM. Additionally, the released Mn2+ could also be utilized as a magnetic resonance imaging contrast agent for monitoring treatment efficiency. Our study demonstrated that this nanoplatform provides an alternative approach to the challenges including low delivery efficiency and drug resistance of chemotherapeutics, which eventually appears to be a potential avenue in GBM treatment.

Glioblastoma stem cells deliver ABCB4 transcribed by ATF3 via exosomes conferring glioblastoma resistance to temozolomide.

Glioblastoma stem cells (GSCs) play a key role in glioblastoma (GBM) resistance to temozolomide (TMZ) chemotherapy. With the increase in research on the tumour microenvironment, exosomes secreted by GSCs have become a new focus in GBM research. However, the molecular mechanism by which GSCs affect drug resistance in GBM cells via exosomes remains unclear. Using bioinformatics analysis, we identified the specific expression of ABCB4 in GSCs. Subsequently, we established GSC cell lines and used ultracentrifugation to extract secreted exosomes. We conducted in vitro and in vivo investigations to validate the promoting effect of ABCB4 and ABCB4-containing exosomes on TMZ resistance. Finally, to identify the transcription factors regulating the transcription of ABCB4, we performed luciferase assays and chromatin immunoprecipitation-quantitative PCR. Our results indicated that ABCB4 is highly expressed in GSCs. Moreover, high expression of ABCB4 promoted the resistance of GSCs to TMZ. Our study found that GSCs can also transmit their highly expressed ABCB4 to differentiated glioma cells (DGCs) through exosomes, leading to high expression of ABCB4 in these cells and promoting their resistance to TMZ. Mechanistic studies have shown that the overexpression of ABCB4 in GSCs is mediated by the transcription factor ATF3. In conclusion, our results indicate that GSCs can confer resistance to TMZ in GBM by transmitting ABCB4, which is transcribed by ATF3, through exosomes. This mechanism may lead to drug resistance and recurrence of GBM. These findings contribute to a deeper understanding of the mechanisms underlying drug resistance in GBM and provide novel insights into its treatment.

PPAR-γ agonists reactivate the ALDOC-NR2F1 axis to enhance sensitivity to temozolomide and suppress glioblastoma progression.

Glioblastoma (GBM) is a type of brain cancer categorized as a high-grade glioma. GBM is characterized by limited treatment options, low patient survival rates, and abnormal serotonin metabolism. Previous studies have investigated the tumor suppressor function of aldolase C (ALDOC), a glycolytic enzyme in GBM. However, it is unclear how ALDOC regulates production of serotonin and its associated receptors, HTRs. In this study, we analyzed ALDOC mRNA levels and methylation status using sequencing data and in silico datasets. Furthermore, we investigated pathways, phenotypes, and drug effects using cell and mouse models. Our results suggest that loss of ALDOC function in GBM promotes tumor cell invasion and migration. We observed that hypermethylation, which results in loss of ALDOC expression, is associated with serotonin hypersecretion and the inhibition of PPAR-γ signaling. Using several omics datasets, we present evidence that ALDOC regulates serotonin levels and safeguards PPAR-γ against serotonin metabolism mediated by 5-HT, which leads to a reduction in PPAR-γ expression. PPAR-γ activation inhibits serotonin release by HTR and diminishes GBM tumor growth in our cellular and animal models. Importantly, research has demonstrated that PPAR-γ agonists prolong animal survival rates and increase the efficacy of temozolomide in an orthotopic brain model of GBM. The relationship and function of the ALDOC-PPAR-γ axis could serve as a potential prognostic indicator. Furthermore, PPAR-γ agonists offer a new treatment alternative for glioblastoma multiforme (GBM).

HMGA1 regulates trabectedin sensitivity in advanced soft-tissue sarcoma (STS): A Spanish Group for Research on Sarcomas (GEIS) study.

HMGA1 is a structural epigenetic chromatin factor that has been associated with tumor progression and drug resistance. Here, we reported the prognostic/predictive value of HMGA1 for trabectedin in advanced soft-tissue sarcoma (STS) and the effect of inhibiting HMGA1 or the mTOR downstream pathway in trabectedin activity. The prognostic/predictive value of HMGA1 expression was assessed in a cohort of 301 STS patients at mRNA (n = 133) and protein level (n = 272), by HTG EdgeSeq transcriptomics and immunohistochemistry, respectively. The effect of HMGA1 silencing on trabectedin activity and gene expression profiling was measured in leiomyosarcoma cells. The effect of combining mTOR inhibitors with trabectedin was assessed on cell viability in vitro studies, whereas in vivo studies tested the activity of this combination. HMGA1 mRNA and protein expression were significantly associated with worse progression-free survival of trabectedin and worse overall survival in STS. HMGA1 silencing sensitized leiomyosarcoma cells for trabectedin treatment, reducing the spheroid area and increasing cell death. The downregulation of HGMA1 significantly decreased the enrichment of some specific gene sets, including the PI3K/AKT/mTOR pathway. The inhibition of mTOR, sensitized leiomyosarcoma cultures for trabectedin treatment, increasing cell death. In in vivo studies, the combination of rapamycin with trabectedin downregulated HMGA1 expression and stabilized tumor growth of 3-methylcholantrene-induced sarcoma-like models. HMGA1 is an adverse prognostic factor for trabectedin treatment in advanced STS. HMGA1 silencing increases trabectedin efficacy, in part by modulating the mTOR signaling pathway. Trabectedin plus mTOR inhibitors are active in preclinical models of sarcoma, downregulating HMGA1 expression levels and stabilizing tumor growth.

Temozolomide resistance mechanisms: unveiling the role of translesion DNA polymerase kappa in glioblastoma spheroids in vitro.

Temozolomide (TMZ) is the leading therapeutic agent for combating Glioblastoma Multiforme (GBM). Nonetheless, the persistence of chemotherapy-resistant GBM cells remains an ongoing challenge, attributed to various factors, including the translesion synthesis (TLS) mechanism. TLS enables tumor cells to endure genomic damage by utilizing specialized DNA polymerases to bypass DNA lesions. Specifically, TLS polymerase Kappa (Polκ) has been implicated in facilitating DNA damage tolerance against TMZ-induced damage, contributing to a worse prognosis in GBM patients. To better understand the roles of Polκ in TMZ resistance, we conducted a comprehensive assessment of the cytotoxic, antiproliferative, antimetastatic, and genotoxic effects of TMZ on GBM (U251MG) wild-type (WTE) and TLS Polκ knockout (KO) cells, cultivated as three-dimensional (3D) tumor spheroids in vitro. Initial results revealed that TMZ: (i) induces reductions in GBM spheroid diameter (10-200 µM); (ii) demonstrates significant cytotoxicity (25-200 µM); (iii) exerts antiproliferative effects (≤25 µM) and promotes cell cycle arrest (G2/M phase) in Polκ KO spheroids when compared with WTE counterparts. Furthermore, Polκ KO spheroids exhibit elevated levels of cell death (Caspase 3/7) and display greater genotoxicity (53BP1) than WTE following TMZ exposure. Concerning antimetastatic effects, TMZ impedes invadopodia (3D invasion) more effectively in Polκ KO than in WTE spheroids. Collectively, the results suggest that TLS Polκ plays a vital role in the survival, cell death, genotoxicity, and metastatic potential of GBM spheroids in vitro when subjected to TMZ treatment. While the precise mechanisms underpinning this resistance remain elusive, TLS Polκ emerges as a potential therapeutic target for GBM patients.

Combination low-dose cyclophosphamide with check-point blockade and ionizing radiation promote an abscopal effect in mouse models of melanoma.

PURPOSE: The complex strategy of hypo-fractionated radiotherapy (HFRT) in combination with an immune checkpoint inhibitor (ICI) can stimulate a potential systemic antitumor response; however, the abscopal effect is always precluded by the tumor microenvironment, which may limit sufficient T-cell infiltration of distant nonirradiated tumors for certain kinds of inhibitory factors, such as regulatory T-cells (Tregs). Additionally, low-dose cyclophosphamide (LD-CYC) can specifically kill regulatory Tregs and strongly synergize antigen-specific immune responses, which could promote an abscopal effect. MATERIALS AND METHODS: We explored whether a triple regimen consisting of HFRT, ICI, and LD-CYC could achieve a better systemic antitumor response in bilateral mouse tumor models. RESULT: Our data demonstrate that LD-CYC combined with HFRT and antiprogrammed cell death ligand 1 (PDL-1) therapy could enhance the abscopal effect than only HFRT/antiPDL-1 or HFRT alone. Surprisingly, repeat CYC doses cannot further restrain tumor proliferation but can prolong murine overall survival, as revealed by the major pathologic responses. These results are associated with increased CD8 + effector T-cell infiltration, although LD-CYC did not upregulate PDL-1 expression in the tumor. CONCLUSIONS: Compared with traditional strategies, for the first time, we demonstrated that a triple treatment strategy remarkably increased the number of radiation-induced tumor-infiltrating CD8 + T-cells, effectively decreasing infiltrating Tregs, and promoting an abscopal effect. Thus, we describe a novel and effective therapeutic approach by combining multiple strategies to target several tumor-mediated immune inhibitory mechanisms.

Lidocaine attenuates TMZ resistance and inhibits cell migration by modulating the MET pathway in glioblastoma cells.

Glioblastoma multiforme (GBM) is the most aggressive type of malignant brain tumor. Currently, the predominant clinical treatment is the combination of surgical resection with concurrent radiotherapy and chemotherapy, using temozolomide (TMZ) as the primary chemotherapy drug. Lidocaine, a widely used amide­based local anesthetic, has been found to have a significant anticancer effect. It has been reported that aberrant hepatocyte growth factor (HGF)/mesenchymal­epithelial transition factor (MET) signaling plays a role in the progression of brain tumors. However, it remains unclear whether lidocaine can regulate the MET pathway in GBM. In the present study, the clinical importance of the HGF/MET pathway was analyzed using bioinformatics. By establishing TMZ­resistant cell lines, the impact of combined treatment with lidocaine and TMZ was investigated. Additionally, the effects of lidocaine on cellular function were also examined and confirmed using knockdown techniques. The current findings revealed that the HGF/MET pathway played a key role in brain cancer, and its activation in GBM was associated with increased malignancy and poorer patient outcomes. Elevated HGF levels and activation of its receptor were found to be associated with TMZ resistance in GBM cells. Lidocaine effectively suppressed the HGF/MET pathway, thereby restoring TMZ sensitivity in TMZ­resistant cells. Furthermore, lidocaine also inhibited cell migration. Overall, these results indicated that inhibiting the HGF/MET pathway using lidocaine can enhance the sensitivity of GBM cells to TMZ and reduce cell migration, providing a potential basis for developing novel therapeutic strategies for GBM.

[99mTc]Tc-labeled HYNIC conjugated chlorambucil as a tumor targeting Agent: Synthesis, characterization and ex-vivo evaluation.

Chlorambucil is an alkylating drug that finds application towards chemotherapy of different types of cancers. In order to explore the possibility of utilization of this drug as an imaging agent for early diagnosis of solid tumors, attempt was made to synthesize a 99mTc complex of chlorambucil and evaluate its potential in tumor bearing small animal model. HYNIC-chlorambucil was synthesized by conjugation of HYNIC with chlorambucil via an ethylenediamine linker. All the intermediates and final product were purified and characterized by standard spectroscopic techniques viz. FT-IR, 1H/13C-NMR as well as by mass spectrometry. HYNIC-chlorambucil conjugate was radiolabeled with [99mTc]Tc and found to be formed with > 95 % radiochemical purity via RP-HPLC studies. The partition coefficient (Log10Po/w) of the synthesized complex was found to be -0.78 ± 0.25 which indicated the moderate hydrophilic nature for the complex. Biological behaviour of [99mTc]Tc-HYNIC-chlorambucil, studied in fibrosarcoma bearing Swiss mice, revealed a tumor uptake of about 4.16 ± 1.52 %IA/g at 30 min post-administration, which declined to 1.91 ± 0.13 % IA/g and 1.42 ± 0.14 %IA/g at 1 h and 2 h post-administration, respectively. A comparison of different [99mTc]Tc-chlorambucil derivatives (reported in the contemporary literature) formulated using different methodologies revealed that tumor uptake and pharmacokinetics exhibited by these agents strongly depend on the lipophilicity/hydrophilicity of such agents, which in turn is dependent on the bifunctional chelators used for formulating the radiolabeled chlorambucils.

A new schedule of one week on/one week off temozolomide as second-line treatment of advanced neuroendocrine carcinomas (TENEC-TRIAL): a multicenter, open-label, single-arm, phase II trial.

BACKGROUND: There is no consensus on the second-line treatment of patients with progressive high-grade neuroendocrine neoplasms (NENs G3) and large-cell lung neuroendocrine carcinoma. These patients generally have poor performance status and low tolerance to combination therapy. In this trial, we aim to evaluate the efficacy and safety of temozolomide given every other week in patients with advanced platinum-pretreated NENs G3. PATIENTS AND METHODS: This trial is an open-label, non-randomized, phase II trial. Patients with platinum-pretreated metastatic neuroendocrine carcinoma were treated with 75 mg/m2/day of temozolomide for 7 days, followed by 7 days of no treatment (regimen one week on/one week off). The primary endpoint was the overall response rate. Secondary endpoints included progression-free survival (PFS), overall survival (OS), safety and tolerability. This study is registered with ClinicalTrials.gov, NCT04122911. RESULTS: From 2017 to 2020, 38 patients were enrolled. Among the patients with determined Ki67, 12 out of 36 (33.3%) had a Ki67 index <55% and the remaining 24 out of 36 (66.6%) had an index ≥55%. Overall response rate was 18% (7/38), including one complete response and six partial responses. The median PFS was 5.86 months [95% confidence interval (CI) 4.8 months-not applicable) and the median OS was 12.1 months (95% CI 5.6-20.4 months). The 1-year PFS rate was 37%. No statistically significant difference in median PFS [hazard ratio 1.3 (95% CI 0.6-2.8); P = 0.44] and median OS [hazard ratio 1.1 (95% CI 0.5-2.4); P = 0.77] was observed among patients with Ki67 <55% versus ≥55%. Only G1-G2 adverse events were registered, the most common being G1 nausea, diarrhea and abdominal pain. CONCLUSION: One week on/one week off temozolomide shows promising activity in patients with poorly differentiated NEN. The good safety profile confirmed the possibility of using this scheme in patients with poor performance status.

Noni enhances the anticancer activity of cyclophosphamide and suppresses myelotoxicity and hepatotoxicity in tumor-bearing mice.

BACKGROUND AND AIM: Morinda citrifolia fruit juice (noni) is an herbal remedy documented to have antioxidant properties. It has been suggested that prevention of carcinogen-DNA adduct formation and the antioxidant activity of NJ may contribute to the cancer preventive effect. In the present study, the antitumor activity of noni was investigated in the presence of cyclophosphamide (CYL) in vitro and in vivo. METHODS: In vitro breast cancer cells (MDA-MB-468) were used to measure the percentage of inhibition and the IC50. The in vivo antitumor activity of noni was studied by monitoring the mean survival time (MST), percentage increase in life span (%ILS), viable and non-viable cell count, tumor volume, body weight, and hematological and serum biochemical parameters in mice. Treatment with noni and CYL exhibited dose- and time-dependent cytotoxicity toward breast cancer cells. RESULTS: Individual treatment of noni and CYL exhibited dose- and time-dependent cytotoxicity on breast cancer cell lines, while in combination therapy of noni and CYL, noni enhances cytotoxic effect of CYL at 48 h than that at 24 h. Similar result was found in in vivo studies, the results of which revealed that alone treatment of CYL and noni suppressed tumor growth. However, combination treatment with CYL and noni presented better tumor inhibition than that of alone treatment of CYL and noni. On the contrary, CYL alone drastically attenuated hematological parameters, i.e., RBC, WBC, and Hb compared to normal and control groups, and this change was reversed and normalized by noni when given as combination therapy with CYL. Moreover, the levels of serum biochemical markers, i.e., AST, ALP, and ALT, were significantly increased in the control and CYL-treated groups than those in the normal group. In the combination treatment of noni and CYL, the above biochemical marker levels significantly decreased compared to CYL alone-treated group. CONCLUSIONS: The present study suggested that CYL treatment can cause serious myelotoxicity and hepatic injury in cancer patients. In conclusion, the combined use of noni with CYL potentially enhances the antitumor activity of CYL and suppresses myelotoxicity and hepatotoxicity induced by CYL in tumor-bearing mice.

A Novel Approach for Glioblastoma Treatment by Combining Apoptosis Inducers (TMZ, MTX, and Cytarabine) with E.V.A. (Eltanexor, Venetoclax, and A1210477) Inhibiting XPO1, Bcl-2, and Mcl-1.

Adjuvant treatment for Glioblastoma Grade 4 with Temozolomide (TMZ) inevitably fails due to therapeutic resistance, necessitating new approaches. Apoptosis induction in GB cells is inefficient, due to an excess of anti-apoptotic XPO1/Bcl-2-family proteins. We assessed TMZ, Methotrexate (MTX), and Cytarabine (Ara-C) (apoptosis inducers) combined with XPO1/Bcl-2/Mcl-1-inhibitors (apoptosis rescue) in GB cell lines and primary GB stem-like cells (GSCs). Using CellTiter-Glo® and Caspase-3 activity assays, we generated dose-response curves and analyzed the gene and protein regulation of anti-apoptotic proteins via PCR and Western blots. Optimal drug combinations were examined for their impact on the cell cycle and apoptosis induction via FACS analysis, paralleled by the assessment of potential toxicity in healthy mouse brain slices. Ara-C and MTX proved to be 150- to 10,000-fold more potent in inducing apoptosis than TMZ. In response to inhibitors Eltanexor (XPO1; E), Venetoclax (Bcl-2; V), and A1210477 (Mcl-1; A), genes encoding for the corresponding proteins were upregulated in a compensatory manner. TMZ, MTX, and Ara-C combined with E, V, and A evidenced highly lethal effects when combined. As no significant cell death induction in mouse brain slices was observed, we conclude that this drug combination is effective in vitro and expected to have low side effects in vivo.

USP19 regulates DNA methylation damage repair and confers temozolomide resistance through MGMT stabilization.

OBJECTIVE: To elucidate the relationship between USP19 and O(6)-methylguanine-DNA methyltransferase (MGMT) after temozolomide treatment in glioblastoma (GBM) patients with chemotherapy resistance. METHODS: Screening the deubiquitinase pannel and identifying the deubiquitinase directly interacts with and deubiquitination MGMT. Deubiquitination assay to confirm USP19 deubiquitinates MGMT. The colony formation and tumor growth study in xenograft assess USP19 affects the GBM sensitive to TMZ was performed by T98G, LN18, U251, and U87 cell lines. Immunohistochemistry staining and survival analysis were performed to explore how USP19 is correlated to MGMT in GBM clinical management. RESULTS: USP19 removes the ubiquitination of MGMT to facilitate the DNA methylation damage repair. Depletion of USP19 results in the glioblastoma cell sensitivity to temozolomide, which can be rescued by overexpressing MGMT. USP19 is overexpressed in glioblastoma patient samples, which positively correlates with the level of MGMT protein and poor prognosis in these patients. CONCLUSION: The regulation of MGMT ubiquitination by USP19 plays a critical role in DNA methylation damage repair and GBM patients' temozolomide chemotherapy response.

p53/E2F7 axis promotes temozolomide chemoresistance in glioblastoma multiforme.

BACKGROUND: Glioblastoma multiforme (GBM) is the most aggressive form of brain cancer, and chemoresistance poses a significant challenge to the survival and prognosis of GBM. Although numerous regulatory mechanisms that contribute to chemoresistance have been identified, many questions remain unanswered. This study aims to identify the mechanism of temozolomide (TMZ) resistance in GBM. METHODS: Bioinformatics and antibody-based protein detection were used to examine the expression of E2F7 in gliomas and its correlation with prognosis. Additionally, IC50, cell viability, colony formation, apoptosis, doxorubicin (Dox) uptake, and intracranial transplantation were used to confirm the role of E2F7 in TMZ resistance, using our established TMZ-resistance (TMZ-R) model. Western blot and ChIP experiments provided confirmation of p53-driven regulation of E2F7. RESULTS: Elevated levels of E2F7 were detected in GBM tissue and were correlated with a poor prognosis for patients. E2F7 was found to be upregulated in TMZ-R tumors, and its high levels were linked to increased chemotherapy resistance by limiting drug uptake and decreasing DNA damage. The expression of E2F7 was also found to be regulated by the activation of p53. CONCLUSIONS: The high expression of E2F7, regulated by activated p53, confers chemoresistance to GBM cells by inhibiting drug uptake and DNA damage. These findings highlight the significant connection between sustained p53 activation and GBM chemoresistance, offering the potential for new strategies to overcome this resistance.

GINS2 regulates temozolomide chemosensitivity via the EGR1/ECT2 axis in gliomas.

Temozolomide (TMZ), a DNA alkylating agent, has become the primary treatment for glioma, the most common malignancy of the central nervous system. Although TMZ-containing regimens produce significant clinical response rates, some patients inevitably suffer from inferior treatment outcomes or disease relapse, likely because of poor chemosensitivity of glioma cells due to a robust DNA damage response (DDR). GINS2, a subunit of DNA helicase, contributes to maintaining genomic stability and is highly expressed in various cancers, promoting their development. Here, we report that GINS2 was upregulated in TMZ-treated glioma cells and co-localized with γH2AX, indicating its participation in TMZ-induced DDR. Furthermore, GINS2 regulated the malignant phenotype and TMZ sensitivity of glioma cells, mostly by promoting DNA damage repair by affecting the mRNA stability of early growth response factor 1 (EGR1), which in turn regulates the transcription of epithelial cell-transforming sequence 2 (ECT2). We constructed a GINS2-EGR1-ECT2 prognostic model, which accurately predicted patient survival. Further, we screened Palbociclib/BIX-02189 which dampens GINS2 expression and synergistically inhibits glioma cell proliferation with TMZ. These findings delineate a novel mechanism by which GINS2 regulates the TMZ sensitivity of glioma cells and propose a promising combination therapy to treat glioma.

Therapy for Vitreous Seeding Caused by Retinoblastoma. A Review.

Retinoblastoma is the most common primary malignant intraocular tumor in children. Seeding, specifically the dispersion of the tumor into the adjacent compartments, represents a major parameter determining the degree of retinoblastoma according to the International Classification of Retinoblastoma. In this article we focused on vitreous seeding, one of the main limiting factors in the successful "eye preservation treatment" of retinoblastoma. This article presents an overview of the history of vitreous seeding of retinoblastoma, established treatment procedures and new-research modalities. The introduction of systemic chemotherapy in the treatment of retinoblastoma at the end of the 1990s represented a significant breakthrough, which enabled the progressive abandonment of radiotherapy with its attendant side effects. However, the attained concentrations of chemotherapeutics in the vitreous space during systemic chemotherapy are not sufficient for the treatment of vitreous seeding, and the toxic effects of systemic chemotherapy are not negligible. A significant change came with the advent of chemotherapy in situ, with the targeted administration of chemotherapeutic drugs, namely intra-arterial and intravitreal injections, contributing to the definitive eradication of external radiotherapy and a reduction of systemic chemotherapy. Although vitreous seeding remains the most common reason for the failure of intra-arterial chemotherapy, this technique has significantly influenced the original treatment regimen of children with retinoblastoma. However, intravitreal chemotherapy has made the greatest contribution to increasing the probability of preservation of the eyeball and visual functions in patients with advanced findings. Novel local drug delivery modalities, gene therapy, oncolytic viruses and immunotherapy from several ongoing preclinical and clinical trials may represent promising approaches in the treatment of vitreous retinoblastoma seeding, though no clinical trials have yet been completed for routine use.

Histone H3K9 Lactylation Confers Temozolomide Resistance in Glioblastoma via LUC7L2-Mediated MLH1 Intron Retention.

Temozolomide (TMZ) resistance remains the major obstacle in the treatment of glioblastoma (GBM). Lactylation is a novel post-translational modification that is involved in various tumors. However, whether lactylation plays a role in GBM TMZ resistance remains unclear. Here it is found that histone H3K9 lactylation (H3K9la) confers TMZ resistance in GBM via LUC7L2-mediated intron 7 retention of MLH1. Mechanistically, lactylation is upregulated in recurrent GBM tissues and TMZ-resistant cells, and is mainly concentrated in histone H3K9. Combined multi-omics analysis, including CUT&Tag, SLAM-seq, and RNA-seq, reveals that H3K9 lactylation is significantly enriched in the LUC7L2 promoter and activates LUC7L2 transcription to promote its expression. LUC7L2 mediates intron 7 retention of MLH1 to reduce MLH1 expression, and thereby inhibit mismatch repair (MMR), ultimately leading to GBM TMZ resistance. Of note, it is identified that a clinical anti-epileptic drug, stiripentol, which can cross the blood-brain barrier and inhibit lactate dehydrogenase A/B (LDHA/B) activity, acts as a lactylation inhibitor and renders GBM cells more sensitive to TMZ in vitro and in vivo. These findings not only shed light on the mechanism of lactylation in GBM TMZ resistance but also provide a potential combined therapeutic strategy for clinical GBM treatment.

EPIC-0628 abrogates HOTAIR/EZH2 interaction and enhances the temozolomide efficacy via promoting ATF3 expression and inhibiting DNA damage repair in glioblastoma.

The efficacy of temozolomide (TMZ) treatment in glioblastoma (GBM) is influenced by various mechanisms, mainly including the level of O6-methylguanine-DNA methyltransferase (MGMT) and the activity of DNA damage repair (DDR) pathways. In our previous study, we had proved that long non-coding RNA HOTAIR regulated the GBM progression and mediated DDR by interacting with EZH2, the catalytic subunit of PRC2. In this study, we developed a small-molecule inhibitor called EPIC-0628 that selectively disrupted the HOTAIR-EZH2 interaction and promoted ATF3 expression. The upregulation of ATF3 inhibited the recruitment of p300, p-p65, p-Stat3 and SP1 to the MGMT promoter. Hence, EPIC-0628 silenced MGMT expression. Besides, EPIC-0628 induced cell cycle arrest by increasing the expression of CDKN1A and impaired DNA double-strand break repair via suppressing the ATF3-p38-E2F1 pathway. Lastly, EPIC-0628 enhanced TMZ efficacy in GBM in vitro and vivo. Hence, this study provided evidence for the combination of epigenetic drugs EPIC-0628 with TMZ for GBM treatment through the above mechanisms.

Exploring Regorafenib Responsiveness and Uncovering Molecular Mechanisms in Recurrent Glioblastoma Tumors through Longitudinal In Vitro Sampling.

Glioblastoma, a deadly brain tumor, shows limited response to standard therapies like temozolomide (TMZ). Recent findings from the REGOMA trial underscore a significant survival improvement offered by Regorafenib (REGO) in recurrent glioblastoma. Our study aimed to propose a 3D ex vivo drug response precision medicine approach to investigate recurrent glioblastoma sensitivity to REGO and elucidate the underlying molecular mechanisms involved in tumor resistance or responsiveness to treatment. Three-dimensional glioblastoma organoids (GB-EXPs) obtained from 18 patients' resected recurrent glioblastoma tumors were treated with TMZ and REGO. Drug responses were evaluated using NAD(P)H FLIM, stratifying tumors as responders (Resp) or non-responders (NRs). Whole-exome sequencing was performed on 16 tissue samples, and whole-transcriptome analysis on 13 GB-EXPs treated and untreated. We found 35% (n = 9) and 77% (n = 20) of tumors responded to TMZ and REGO, respectively, with no instances of TMZ-Resp being REGO-NRs. Exome analysis revealed a unique mutational profile in REGO-Resp tumors compared to NR tumors. Transcriptome analysis identified distinct expression patterns in Resp and NR tumors, impacting Rho GTPase and NOTCH signaling, known to be involved in drug response. In conclusion, recurrent glioblastoma tumors were more responsive to REGO compared to TMZ treatment. Importantly, our approach enables a comprehensive longitudinal exploration of the molecular changes induced by treatment, unveiling promising biomarkers indicative of drug response.

A chloromethyl-triazole fluorescent chemosensor for O6-methylguanine DNA methyltransferase.

Fluorescent chemosensors offer a direct means of measuring enzyme activity for cancer diagnosis, predicting drug resistance, and aiding in the discovery of new anticancer drugs. O6-methylguanine DNA methyltransferase (MGMT) is a predictor of resistance towards anticancer alkylating agents such as temozolomide. Using the fluorescent molecular rotor, 9-(2-carboxy-2-cyanovinyl)julolidine (CCVJ), we synthesized, and evaluated a MGMT fluorescent chemosensor derived from a chloromethyl-triazole covalent inhibitor, AA-CW236, a non-pseudosubstrate of MGMT. Our fluorescence probe covalently labelled the MGMT active site C145, producing a 18-fold increase in fluorescence. Compared to previous fluorescent probes derived from a substrate-based inhibitor, our probe had improved binding and reaction rate. Overall, our chloromethyl triazole-based fluorescence MGMT probe is a promising tool for measuring MGMT activity to predict temozolomide resistance.