Continuous and bolus intraventricular topotecan prolong survival in a mouse model of leptomeningeal medulloblastoma

Beyond the brain: exploring the impact of animal models of leptomeningeal disease from solid tumors

Leptomeningeal disease (LMD) is a devastating manifestation of late-stage cancer which currently suffers from a lack of effective therapeutics. Unfortunately, a significant obstacle preventing the widespread development and testing of therapeutics for LMD is the lack of biologically accurate animal models. We provide overviews of six types of animal models of leptomeningeal metastasis from solid tumors: injection of tumor cells into the cerebrospinal fluid (CSF), blood, or brain parenchyma; subcutaneous or mammary fat pad injection of tumor cells; the LeptoM/LM-phenotype model; and genetic manipulation. We identify the pros and cons of each model and suggest broad areas of future research that could improve each model in terms of its similarity to human LMD.

The path to leptomeningeal metastasis

The leptomeninges, the cerebrospinal-fluid-filled tissues surrounding the central nervous system, play host to various pathologies including infection, neuroinflammation and malignancy. Spread of systemic cancer into this space, termed leptomeningeal metastasis, occurs in 5-10% of patients with solid tumours and portends a bleak clinical prognosis. Previous, predominantly descriptive, clinical studies have provided few insights. Recent development of preclinical leptomeningeal metastasis models, alongside genomic, transcriptomic and proteomic sequencing efforts, has provided groundwork for mechanistic understanding and identification of long-needed therapeutic targets. Although previously understood as an anatomically isolated compartment, the leptomeninges are increasingly appreciated as a major conduit of communication between the systemic circulation and the central nervous system. Despite the unique nature of the leptomeningeal microenvironment, the general principles of metastasis hold true: cells metastasizing to the leptomeninges must gain access to the new environment, survive within the space and evade the immune system. The study of leptomeningeal metastasis has the potential to uncover novel site-specific metastatic principles and illuminate the physiology of the leptomeningeal space. In this Review, we provide a biology-focused overview of how metastatic cells reach the leptomeninges, thrive in this nutritionally sparse environment and evade the detection of the omnipresent immune system.

The OTX2 Gene Induces Tumor Growth and Triggers Leptomeningeal Metastasis by Regulating the mTORC2 Signaling Pathway in Group 3 Medulloblastomas

Medulloblastoma (MB) encompasses diverse subgroups, and leptomeningeal disease/metastasis (LMD) plays a substantial role in associated fatalities. Despite extensive exploration of canonical genes in MB, the molecular mechanisms underlying LMD and the involvement of the orthodenticle homeobox 2 (OTX2) gene, a key driver in aggressive MB Group 3, remain insufficiently understood. Recognizing OTX2's pivotal role, we investigated its potential as a catalyst for aggressive cellular behaviors, including migration, invasion, and metastasis. OTX2 overexpression heightened cell growth, motility, and polarization in Group 3 MB cells. Orthotopic implantation of OTX2-overexpressing cells in mice led to reduced median survival, accompanied by the development of spinal cord and brain metastases. Mechanistically, OTX2 acted as a transcriptional activator of the Mechanistic Target of Rapamycin (mTOR) gene's promoter and the mTORC2 signaling pathway, correlating with upregulated downstream genes that orchestrate cell motility and migration. Knockdown of mTOR mRNA mitigated OTX2-mediated enhancements in cell motility and polarization. Analysis of human MB tumor samples (N = 952) revealed a positive correlation between OTX2 and mTOR mRNA expression, emphasizing the clinical significance of OTX2's role in the mTORC2 pathway. Our results reveal that OTX2 governs the mTORC2 signaling pathway, instigating LMD in Group 3 MBs and offering insights into potential therapeutic avenues through mTORC2 inhibition.

Medulloblastoma targeted therapy: From signaling pathways heterogeneity and current treatment dilemma to the recent advances in development of therapeutic strategies

Medulloblastoma (MB) is a major pediatric malignant brain tumor that arises in the cerebellum. MB tumors exhibit highly heterogeneous driven by diverse genetic alterations and could be divided into four major subgroups based on their different biological drivers and molecular features (Wnt, Sonic hedgehog (Shh), group 3, and group 4 MB). Even though the therapeutic strategies for each MB subtype integrate their pathogenesis and were developed to focus on their specific target sites, the unexpected drug non-selective cytotoxicity, low drug accumulation in the brain, and complexed MB tumor microenvironment still be huge obstacles to achieving satisfied MB therapeutic efficiency. This review discussed the current advances in modern MB therapeutic strategy development. Through the recent advances in knowledge of the origin, molecular pathogenesis of MB subtypes and their current therapeutic barriers, we particularly reviewed the current development in advanced MB therapeutic strategy committed to overcome MB treatment obstacles, focusing on novel signaling pathway targeted therapeutic agents and their combination discovery, advanced drug delivery systems design, and MB immunotherapy strategy development.

Cytotoxic and Apoptotic Effects of Celecoxib and Topotecan on AGS and HEK 293 Cell Lines

PURPOSE

This study is aimed to assess the anti-cancer effects of Celecoxib and topotecan against Human Gastric cancer cell line (AGS) in comparison to the control in an in-vitro study.

METHODS

In this experimental study, Celecoxib and topotecan was prepared at concentrations of 500, 250, 125, 62.5, 31.2, 15.6 and 7.8 mg/ml. The effect of celecoxib and topotecan separately and in mixed form were investigated on AGS and normal HEK cells. To investigate the cell survival, MTT method was used to study the pathway of apoptosis using flowcytometry and Caspase kits based on colorimetric. Finally, one-way ANOVA and t-test were used to analyze the data.

RESULTS

The results of this study indicated that Celecoxib was cytotoxic against AGS and HEK cell lines. The topotecan indicated a significant cytotoxicity against AGS cells and was not toxic against HEK cell line. Our results indicated that Celecoxib and topotecan have synergist effects against AGS and HEK cell lines and were more effective than separate celecoxib or topotecan.

CONCLUSION

The mixture of clecoxib and topotecan was more effective than celecoxib and topotecan in separate form. Our results indicated that use mixed forms of treatments can cause excellent therapeutic effects and can cause less side effects.