Expression of 58-kD Microspherule Protein (MSP58) is Highly Correlated with PET Imaging of Tumor Malignancy and Cell Proliferation in Glioma Patients.

BACKGROUND/AIMS: The nucleolar 58-kDa microspherule protein (MSP58) has important transcriptional regulation functions and plays a crucial role in the tumorigenesis and progression of cancers. 3'-deoxy-3'-[18F]fluorothymidine (FLT) has emerged as a promising positron emission tomography (PET) tracer for evaluating tumor malignancy and cell proliferation.

METHODS

In the present study, the expression of MSP58 was evaluated by immunohistochemistry and the corresponding PET image was examined using FLT-PET in 55 patients with various grades of gliomas.

RESULTS

The immunoreactivity score (IRS) of MSP58 increased with tumor grade with grade IV gliomas exhibiting the highest expression and showed a highly significant positive correlation with the Ki-67 index (r = 0.65, P < 0.001). The IRS of MSP58 in the tumor showed a highly significant positive correlation with corresponding FLT uptake value (r = 0.61, P < 0.001). The correlation between MSP58 expression and glioma malignancy was also confirmed by immunofluorescence, RT-PCR and western blot analysis. FLT uptake value also exhibited a highly significant positive correlation with the Ki-67 index (r = 0.59, P < 0.001). Kaplan-Meier analysis revealed that MSP58 expression has a significant prognostic ability for the overall survival time similar to that found in the uptake value of FLT-PET.

CONCLUSION

These results indicate that MSP58 plays an important role in cell proliferation and will be one of the potential candidates of molecular therapy targeting proliferation. FLT-PET might be used as an early measure of treatment response in the proliferation-targeted therapy.