Boric acid impedes glioblastoma growth in a rat model: insights from multi-approach analysis

Abstract

Limited advancements in managing malignant brain tumors have resulted in poor prognoses for glioblastoma (GBM) patients. Standard treatment involves surgery, radiotherapy, and chemotherapy, which lack specificity and damage healthy brain tissue. Boron-containing compounds, such as boric acid (BA), exhibit diverse biological effects, including anticancer properties. This study aimed to examine whether boron supplementation, as BA, can inhibit glioblastoma growth in a xenograft animal model. Using MRI-based tumor size measurement, survival rates, hematological, clinical biochemistry analyses, and genotoxicity parameters, we assessed the impact of BA. Histopathological, immunohistochemical, and immunofluorescence examinations were also conducted. All BA doses (3.25, 6.5, and 13 mg kg^-1 b.w.) extended survival compared to GBM controls after 14 days, with a dose-dependent anti-GBM effect observed in MRI analyses. BA treatment improved hematological (WBC and PLT counts) and biochemical parameters (LDL-C, CREA, and ALP). Histopathological examination revealed a significant reduction in tumor diameter with 6.5 and 13 mg kg^-1 BA. Immunohistochemical and immunofluorescence staining showed modulation of intracytoplasmic Ki67, cytoplasmic CMPK2, and GFAP expressions in tumor cells post-BA treatment. Additionally, BA did not increase micronuclei formations, indicating its non-genotoxic nature. In conclusion, targeting tumor suppressor networks with boron demonstrates significant therapeutic potential for GBM treatment.

Keywords: Anticancer; Boric acid; Boron; Glioblastoma; Xenograft rat model.

Fig. 1

The survival rates of rats within each experimental group

Fig. 2

MRI monitoring of tumor advancement in the GBM model after treatment with different BA doses. Different letters indicate statistically significant differences (p < 0.05)

Fig. 3

MRI images of the rat brain with GBM: A axial T2-weighted MRI image taken on the 14th day post-implantation; B axial T2-weighted MRI image captured on the 28th day post-implantation; C coronal T2-weighted MRI image obtained on the 14th day post-implantation; D coronal T2-weighted MRI image acquired on the 28th day post-implantation

Fig. 4

MRI images of the rat brain with GBM: A Axial T2-weighted MRI image obtained on the 14th day post-implantation; B Axial T2-weighted MRI image following treatment with B1 on the 28th day; C Coronal T2-weighted MRI image taken on the 14th day post-implantation; D Coronal T2-weighted MRI image after treatment with B1 on the 28th day

Fig. 5

MRI images of the rat brain with GBM: A Axial T2-weighted MRI image obtained on the 14th day post-implantation; B Axial T2-weighted MRI image following treatment with B2 on the 28th day; C Coronal T2-weighted MRI image taken on the 14th day post-implantation; D Coronal T2-weighted MRI image after treatment with B2 on the 28th day

Fig. 6

MRI images of the rat brain with GBM: A axial T2-weighted MRI image obtained on the 14th day post-implantation; B Axial T2-weighted MRI image following treatment with B2 on the 28th day; C Coronal T2-weighted MRI image taken on the 14th day post-implantation; D Coronal T2-weighted MRI image after treatment with B2 on the 28th day

Fig. 7

Brain tissue, glioblastoma, tumor foci (thick arrows), H&E staining, scale bar: 70 µm. Ki67 expressions in the tumor cell (thin arrows), CMPK2 expressions in anaplastic cells (arrow heads), and GFAP expressions in astrocytes surrounding the mass (curved arrows) detected via IHC-P, Scale bar: 40 µm

Fig. 8

Histopathological findings observed in brain tissues: tumor mass: (****p < 0.0001, ***p = 0.0007, ns p = 0.3550); Focus of Necrosis: (****p < 0.0001, ns p = 0.9136); Vascular proliferation: (***p = 0.0003, *** p = 0.0002 (GBM vs B3); Cellular proliferation: (***p = 0.0007, ***p = 0.0002 (GBM vs B3)

Fig. 9

Brain tissues with GBM showing NOP10 and H2A.X expressions in neurons, immunofluorescence staining. Scale bar: 50 µm

Fig. 10

Immunohistochemical and immunofluorescence staining data. Ki67: (****p < 0.0001, **p = 0.0010, ns p = 0.8510); CMPK2: (****p < 0.0001, **p = 0.0012, ns p = 0.4314); GFAP: (****p < 0.0001, ns p = 0.2238); NOP10: (****p < 0.0001, ***p = 0.0002, *p = 0.0480); H2A.X: (****p < 0.0001, ***p = 0.0003, ns p = 0.0979); ns indicates no significant difference