Fluorine-18-deoxyglucose positron emission tomography/computed tomography with Ki67 and GLUT-1 immunohistochemistry for evaluation of the radiosensitization effect of oleanolic acid on C6 rat gliomas

Exploring the efficacy of 18F-FDG PET/CT in hepatocellular carcinoma diagnosis: role of Ki-67 index and tumor differentiation

PURPOSE

The sensitivity of [18F] fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG PET/CT) for detecting hepatocellular carcinoma (HCC) has not been clarified thoroughly. Our study seeks to explore the association between the Ki-67 index and FDG-avidity in HCC tumors using 18F-FDG PET/CT.

METHODS

112 HCC lesions from 109 patients detected by 18F-FDG PET/CT were included retrospectively between August 2017 and May 2022, comprising 82 lesions in the training cohort and 30 in the validation cohort to simulate prospective studies. In the training cohort, lesions were stratified by a lesion-to-liver maximum standardized uptake value (SUVmax) ratio cut-off of 1.59. The relationships between lesion-to-liver SUVmax ratios and several clinical factors including tumor differentiation, alpha fetoprotein (AFP), carcinoembryonic antigen (CEA), hepatitis B virus (HBV) infection, Ki-67 index et al. were assessed. These findings were subsequently validated in the independent validation cohort.

RESULTS

In the training cohort, group A1 lesions demonstrated a higher Ki-67 index (%, 40.00 [30.00, 57.50] vs. 10.00 [5.00, 28.75], p<0.001) than group A0, the positive correlation between FDG-avidity and Ki-67 index was revealed by multivariate analysis, OR=1.040, 95% CI of OR [1.004-1.077], p=0.030. The calculated cut-off value was 17.5% using the receiver operating characteristic (ROC) curve, with an area under curve (AUC) of 0.834 and 95% CI [0.742-0.926], p<0.001. These findings were further validated in the independent validation cohort, with similar results (AUC=0.875, 95% CI [0.750-1.000], p<0.001).

CONCLUSION

In comparison to tumor differentiation, Ki-67 index demonstrates a stronger association with FDG-avidity in HCC tumors, and when the Ki-67 index exceeds 17.5%, 18F-FDG PET/CT might serve as a useful indicator for HCC.

Progress and Viewpoints of Multifunctional Composite Nanomaterials for Glioblastoma Theranostics

The most common malignant tumor of the brain is glioblastoma multiforme (GBM) in adults. Many patients die shortly after diagnosis, and only 6% of patients survive more than 5 years. Moreover, the current average survival of malignant brain tumors is only about 15 months, and the recurrence rate within 2 years is almost 100%. Brain diseases are complicated to treat. The reason for this is that drugs are challenging to deliver to the brain because there is a blood–brain barrier (BBB) protection mechanism in the brain, which only allows water, oxygen, and blood sugar to enter the brain through blood vessels. Other chemicals cannot enter the brain due to their large size or are considered harmful substances. As a result, the efficacy of drugs for treating brain diseases is only about 30%, which cannot satisfy treatment expectations. Therefore, researchers have designed many types of nanoparticles and nanocomposites to fight against the most common malignant tumors in the brain, and they have been successful in animal experiments. This review will discuss the application of various nanocomposites in diagnosing and treating GBM. The topics include (1) the efficient and long-term tracking of brain images (magnetic resonance imaging, MRI, and near-infrared light (NIR)); (2) breaking through BBB for drug delivery; and (3) natural and chemical drugs equipped with nanomaterials. These multifunctional nanoparticles can overcome current difficulties and achieve progressive GBM treatment and diagnosis results.

Hypoxia Imaging and Biological Evaluation of the Radiosensitizing Effect of Oleanolic Acid

Background and Purpose

The aim of this study was to evaluate the radiosensitizing effect of oleanolic acid (OA) on C6 rat glioma and the changes in tumor biology during radiosensitization therapy on ¹⁸F-fluoromisonidazole (¹⁸F-FMISO) positron emission tomography/computed tomography (PET/CT).

Methods

The radiosensitizing effect of OA on C6 tumors was assessed in vivo by measuring the tumor inhibitory rate and rat survival time. Meanwhile, rats with C6 tumors were imaged with ¹⁸F-FMISO PET/CT during radiosensitization therapy. Tumor-to-muscle ratio (TMR) of ¹⁸F-FMISO maximum uptake was calculated by region of interest analysis. Changes in tumor biology after therapy were assessed with immunohistochemical staining. ¹⁸F-FMISO uptake was analyzed in relation to expression of tumor biomarkers including hypoxia-inducible factor (HIF)-1α, glucose transporter (Glut-1), the proliferation antigen Ki67, tumor suppressor P53, and microvessel density (MVD).

Results

The results showed that OA combined with radiation inhibited the growth rates of tumors and prolonged the survival period of tumor-bearing rats effectively (χ² = 12.5, p < 0.01). ¹⁸F-FMISO PET/CT indicated decreases in hypoxia after radiosensitization therapy. Statistical differences were observed in TMR of the irradiation group and OA combined with irradiation group (t = 3.32, p < 0.05). HIF-1α, Glut-1, Ki67, P53, and MVD expressions in tumors were downregulated by OA combined with radiation as well as with radiation alone. Additionally, there was a significant positive linear correlation between TMR and HIF-1α, Glut-1, Ki67, P53, and MVD.

Conclusions

These results suggest that OA has a radiosensitizing effect on C6 tumors in terms of tumor volume inhibition, survival extension, and multiple poor prognosis biological markers downregulation. ¹⁸F-FMISO PET/CT can be of value for tumor biology noninvasive capture and radiosensitization response evaluation.

Investigation of hypoxia conditions using oxygen-enhanced magnetic resonance imaging measurements in glioma models

The objective of this study was to determine whether using oxygen-enhanced magnetic resonance imaging (OE-MRI) to assess hypoxia is feasible and whether historical measurements, pO2 changes, and percentage of signal intensity changes (PSIC) are correlated in an animal model of glioma. A total of 25 Sprague-Dawley rats were used to establish C6 brain or subcutaneous glioma model. Nine rats with brain gliomas underwent OE-MRI followed by histopathologic analysis to assess microvessel density and hypoxia. Another 11 rats were underwent OE-MRI and were followed for a survival analysis. Time-T1-weighted MR signal intensity (SI) curves and PSIC maps were derived from the OE-MRI data. High-regions of interests (ROI-h; PSIC > 10%) and low-ROIs (ROI-l; PSIC < 10%) were defined on the PSIC maps. To validate the PSIC map for identifying tumor hypoxia, we subjected an additional 5 rats with subcutaneous glioma to OE-MRI and pO2 measurements. All tumors showed regional heterogeneity on the PSIC maps. For the brain tumors, the time-SI curves for the ROIs-h showed a greater increase in SI than those for the ROIs-l did. The percentage of tumor area with a low PSIC was significantly correlated with the percentage of hypoxia staining and necrosis (r =0.71; P<0.05). ROIs with a higher PSIC typically had more vessels (r=0.88; P<0.05). A significant difference in survival was shown (log-rank P = 0.035). The time-pO2 curves of the subcutaneous tumors were similar to the time-SI curves. PSIC was significantly correlated with pO2 changes (r =0.82; P<0.05). These findings suggest that OE-MRI measurements can be used to assess hypoxia in C6 glioma models. In these models, the PSIC value was correlated with survival, indicating that PSIC could serve as a prognostic marker for glioma.

Breast cancer subtype specific biochemical responses to radiation

External beam radiotherapy is a common form of treatment for breast cancer.

A study of the synergistic effect of folate-decorated polymeric micelles incorporating Hydroxycamptothecin with radiotherapy on xenografted human cervical carcinoma

In this study, Hydroxycamptothecin (HCPT)-loaded micelles were formed in water by the self-assembly of folate (FA)-decorated amphiphilic block copolymer, methoxy poly(ethylene glycol)-poly(ε-caprolactone) (MPEG-PCL), and achieved a hydrodynamic diameter about of 132 nm. HCPT release from the micelles exhibited no initial burst but showed a sustained release profile. The cytotoxicity and targeting ability of FA conjugated polymeric micelles was investigated by using methylthiazoletetrazolium (MTT) and fluorescence microscopy. We found that FA-conjugated micelles had superior cytotoxicity against HeLa cells compared to non-conjugated micelles, and that they exerted this effect by folate receptor (FR)-mediated endocytosis. In addition, HeLa cells were xenografted into nude mice and subjected to radiotherapy (RT) and/or HCPT-loaded micelle treatment. The antitumor efficacy was detected by analysis of tumor growth delay (TGD) and median survival time. Micro fluorine-18-deoxyglucose PET/computed tomography ((18)F-FDG PET/CT) was performed to assess early tumor response to HCPT-loaded micelles in combination with RT. Analysis of cell cycle redistribution, apoptosis and expression of histone H2AX phosphorylation (λ-H2AX) was used to evaluate the mechanism by which HCPT loaded micelles led to radiosensitization. Taken together, the results showed that HCPT-loaded FA decorated micelles efficiently sensitized xenografts in mice to RT, and induced G2/M phase arrest, apoptosis and expression of λ-H2AX.