MicroRNA-221/222 Inhibits the Radiation-Induced Invasiveness and Promotes the Radiosensitivity of Malignant Meningioma Cells.

The controversy of adjuvant radiotherapy of meningiomas is at least partially due to the insufficient understanding on meningioma cells' response to irradiation and the shortage of radiosensitivity-promotion methods. MicroRNA-221 and microRNA-222 were identified as critical regulators of radiosensitivity in several other tumors. However, their effect in meningiomas has yet to be confirmed. Therefore, the malignant meningioma IOMM-Lee cells were adopted, transfected with microRNA-221/222 mimics or inhibitors, and irradiated with different dosages. The effects of radiation and microRNA-221/222 were then assessed in vitro and in vivo. Radiation dose increases and microRNA-221/222 downregulation synergistically inhibited cell proliferation and colony formation, prevented xenograft tumor progression, and promoted apoptosis, but antagonistically regulated cell invasiveness. Pairwise comparisons revealed that only high-dose radiations (6 and 8 Gy) can significantly promote cell invasiveness in comparison with unirradiated counterparts. Further comparisons exhibited that downregulating the microRNA-221/222 expression can reverse this radiation-induced cell invasiveness to a level of untransfected and unirradiated cells only if cells were irradiated with no more than 6 Gy. In addition, this approach can promote IOMM-Lee's radiosensitivity. Meanwhile, we also detected that the dose rate of irradiation affects cell cycle distribution and cell apoptosis of IOMM-Lee. A high dose rate irradiation induces G0/G1 cell cycle arrest and apoptosis-promoting effect. Therefore, for malignant meningiomas, high-dose irradiation can facilitate cell invasiveness significantly. Downregulating the microRNA-221/222 level can reverse the radiation-induced cell invasiveness while enhancing the apoptosis-promoting and proliferation-inhibiting effects of radiation and promoting cell radiosensitivity.

11C-CHO PET in optimization of target volume delineation and treatment regimens in postoperative radiotherapy for brain gliomas.

OBJECTIVE: We explored the clinical values of (11)C-choline ((11)C-CHO) PET in optimization of target volume delineation and treatment regimens in postoperative radiotherapy for brain gliomas. METHODS: Sixteen patients with the pathological confirmation of the diagnosis of gliomas prior to receiving radiotherapy (postoperative) were included, and on whom both MRI and CHO PET scans were performed at the same position for comparison of residual tumors with the two techniques. (11)C-CHO was used as the tracer in the PET scan. A plain T1-weighted, T2-weighted and contrast-enhanced T1-weighted imaging scans were performed in the MRI scan sequence. The gliomas' residual tumor volume was defined as the area with CHO-PET high-affinity uptake and metabolism (V(CHO)) and one with MRI T1-weighted imaging high signal intensity (V(Gd)), and was determined by a group of experienced professionals and clinicians. RESULTS: (1) In CHO-PET images, the tumor target volume, i.e., the highly metabolic area with a high concentration of isotopes (SUV 1.016-4.21) and the corresponding contralateral normal brain tissues (SUV0.1-0.62), was well contrasted, and the boundary between lesions and surrounding normal brain tissues was better defined compared with MRI and (18)F-FDG PET images. (2) For patients with brain gliomas of WHO Grade II, the SUV was 1.016-2.5; for those with WHO Grades III and IV, SUVs were >26-4.2. (3) Both CHO PET and MRI were positive for 10 patients and negative for 2 patients. The residual tumor consistency between these two studies was 75%. Four of the 10 CHO-PET-positive patients were negative on MRI scans. The maximum distance between V(Gd) and V(CHO) margins was 1.8 cm. (4) The gross tumor volumes (GTVs) and the ensuing treatment regimens were changed for 31.3% (5/16) of patients based on the CHO-PET high-affinity uptake and metabolism, in which the change rate was 80% (4/5), 14.3 % (1/7) and 0% (0/4) for patients with WHO Grade II III, and IV gliomas, respectively. CONCLUSION: Our data demonstrate that difference exists between CHO PET and MRI by which to judge and identify residual tumor for patients with brain gliomas. CHO PET is considered to be a supplementary diagnostic approach for MRI. Biological tumor target volume (BTV) displayed in the CHO PET images is useful in determining or delineating the radiotherapy target volume and making decisions in selecting treatment regimens. Tumor target volume may be defined more accurately and rationally when the CHO PET is combined with MRI.

[Expression and significance of P-glycoprotein, glutathione S-transferase-pi and Topoisomerase II in gastric carcinomas].

BACKGROUND & OBJECTIVE: Multi-drug resistance(MDR) is the most important failing reason of tumor chemotherapy, the substance that P-glycoprotein(P-gp), glutathione S-transferase-pi(GST-pi), Topoisomerase II (Topo II) etc was the fundamental substances producing MDR. Gastric carcinoma is the relatively familiar malignancy, the report was relatively fewness that the expression of P-gp, GST-pi and Topo II by means of immunohistochemistry were associated with in the gastric carcinomas of previously untreated patients. This study was designed to investigate the expression and significance of P-gp, glutathione S-transferase-pi(GST-pi) and Topoisomerase II(Topo II) in gastric carcinomas. METHODS: Seventy-five human gastric carcinomas of previously untreated patients were studied for the expression of P-gp, GST-pi and Topo II by means of immunohistochemistry. RESULTS: The expression of P-gp, GST-pi and Topo II were 76.0%, 85.3% and 68.0% in gastric carcinoma tissues. There was no significant relationship between the expression levels and age, sex, location of tumor and depth of tumor invasion. Positive rate was higher in glandular-form carcinoma than that in mucoid carcinoma, signet-ring cell carcinoma and poorly differentiated carcinoma (P < 0.05). There was a significant relationship between the lymph node involvement and the higher expression of P-gp, GST-pi, lower expression of Topo II. CONCLUSION: There is a correlation between the expression of P-gp, GST-pi, Topo II and histologic subtypes, the expression may also related to the differentiation and metastasis of the gastric carcinomas.