Albumin-bound paclitaxel augment temozolomide treatment sensitivity of glioblastoma cells by disrupting DNA damage repair and promoting ferroptosis.

BACKGROUND: Temozolomide (TMZ) treatment efficacy in glioblastoma (GBM) patients has been limited by resistance in the clinic. Currently, there are no clinically proven therapeutic options available to restore TMZ treatment sensitivity. Here, we investigated the potential of albumin-bound paclitaxel (ABX), a novel microtubule targeting agent, in sensitizing GBM cells to TMZ and elucidated its underlying molecular mechanism. METHODS: A series of in vivo and in vitro experiments based on two GBM cell lines and two primary GBM cells were designed to evaluate the efficacy of ABX in sensitizing GBM cells to TMZ. Further proteomic analysis and validation experiments were performed to explore the underlying molecular mechanism. Finally, the efficacy and mechanism were validated in GBM patients derived organoids (PDOs) models. RESULTS: ABX exhibited a synergistic inhibitory effect on GBM cells when combined with TMZ in vitro. Combination treatment of TMZ and ABX was highly effective in suppressing GBM progression and significantly prolonged the survival oforthotopic xenograft nude mice, with negligible side effects. Further proteomic analysis and experimental validation demonstrated that the combined treatment of ABX and TMZ can induce sustained DNA damage by disrupting XPC and ERCC1 expression and nuclear localization. Additionally, the combination treatment can enhance ferroptosis through regulating HOXM1 and GPX4 expression. Preclinical drug-sensitivity testing based on GBM PDOs models confirmed that combination therapy was significantly more effective than conventional TMZ monotherapy. CONCLUSION: Our findings suggest that ABX has the potential to enhance TMZ treatment sensitivity in GBM, which provides a promising therapeutic strategy for GBM patients.

IKBIP, a novel glioblastoma biomarker, maintains abnormal proliferation of tumor cells by inhibiting the ubiquitination and degradation of CDK4.

Sustained proliferative signaling is a crucial hallmark and therapeutic target in glioblastoma (GBM); however, new intrinsic regulators and their underlying mechanisms remain to be elucidated. In this study, I kappa B kinase interacting protein (IKBIP) was identified to be correlated with the progression of GBM by analysis of The Cancer Genome Atlas (TCGA) data. TCGA database analysis indicated that higher IKBIP expression was associated with high tumor grade and poor prognosis in GBM patients, and these correlations were subsequently validated in clinical samples. IKBIP knockdown induced G1/S arrest by blocking the Cyclin D1/CDK4/CDK6/CDK2 pathway. Our results showed that IKBIP may bind directly to CDK4, a key cell cycle checkpoint protein, and prevent its ubiquitination-mediated degradation in GBM cells. An in vivo study confirmed that IKBIP knockdown strongly suppressed cell proliferation and tumor growth and prolonged survival in a mouse xenograft model established with human GBM cells. In conclusion, IKBIP functions as a novel driver of GBM by binding and stabilizing the CDK4 protein. IKBIP could be a potential therapeutic target in GBM.

The Ependymal Region Prevents Glioblastoma From Penetrating Into the Ventricle via a Nonmechanical Force.

BACKGROUND: Intraventricular penetration is rare in glioblastoma (GBM). Whether the ependymal region including the ependyma and subventricular zone (SVZ) can prevent GBM invasion remains unclear. METHODS: Magnetic resonance imaging (MRI) and haematoxylin-eosin (HE) staining were performed to evaluate the size and anatomical locations of GBM. Binary logistic regression analysis was used to assess the correlation between tumor-ependyma contact, ventricle penetration and clinical characteristics. Cell migration and invasion were assessed via Transwell assays and an orthotopic transplantation model. RESULTS: Among 357 patients with GBM, the majority (66%) showed ependymal region contact, and 34 patients (10%) showed ventricle penetration of GBM. GBM cells were spread along the ependyma in the orthotopic transplantation model. The longest tumor diameter was an independent risk factor for GBM-ependymal region contact, as demonstrated by univariate (OR = 1.706, p < 0.0001) and multivariate logistic regression analyses (OR = 1.767, p < 0.0001), but was not associated with ventricle penetration. Cerebrospinal fluid (CSF) could significantly induce tumor cell migration (p < 0.0001), and GBM could grow in CSF. Compared with those from the cortex, cells from the ependymal region attenuated the invasion of C6 whether cocultured with C6 or mixed with Matrigel (p = 0.0054 and p = 0.0488). Immunofluorescence analysis shows a thin gap with GFAP expression delimiting the tumor and ependymal region. CONCLUSION: The ependymal region might restrict GBM cells from entering the ventricle via a non-mechanical force. Further studies in this area may reveal mechanisms that occur in GBM patients and may enable the design of new therapeutic strategies.