Quantitative tissue analysis reveals AK2, COL1A1, and PLG protein signatures: targeted therapeutics for meningioma
Authors: Sharma Swati , Shamjetsabam Nandibala Devi , Chauhan Kirti , Yashavarddhan M.H. , Gautam Poonam , Prakash Prem , Choudhary Priyanka , Chhabra Satnam S. , Acharya Rajesh , Kalra Samir K. , Gupta Anshul , Jain Sunila , Ganguly Nirmal K. , Rana Rashmi 
Published: September 2024

Background:
Meningioma is the most prevalent primary intracranial brain tumor and accounts for one-third of all CNS tumors. Meningioma is known to be the most common yet life-threatening brain tumor with a higher recurrence rate. Globally, there is an increase in the healthcare burden due to meningioma and hence in its research. The present clinical approach includes surgical resection, chemotherapy, and radiation therapies to which the malignancy does not seem to respond efficiently. Targeted therapies and molecular markers provide elite patient treatment and care for individuals suffering from meningiomas as compared to conventional measures. Although there is proteomic data on meningioma the knowledge of potential biomarkers differentiating the grades is scarce. To identify the best set of biomarkers, validation of reported markers in large and independent sample cohorts in the future is necessary.

Methods:
A total of 12 samples, 3 each of control (which made pool 1) meningioma grade I (which made 2 sets: pool 2 and pool 3), and meningioma grade II (which made pool 4) were taken for LC-MS/MS. After this, the expression of three proteins was checked by immunocytochemistry, flow cytometry, and western blotting.

Results:
Protein expression was analyzed using various techniques like mass spectrometry, immunocytochemistry, flow cytometry, and western blotting. Mass spectrometry is the most commonly used standard and reliable technique for identifying and quantifying protein expression. We got three highly upregulated proteins namely AK2, COL1A1, and PLG using this technique. The biomarker potential of these proteins was further checked by ICC, western blotting, and flow cytometry. Three important proteins were found to be upregulated namely, AK2 (Adenylate kinase 2), COL1A1 (collagen 1A1), and PLG (plasminogen). The order of increased protein expression was control < MG grade I < MG grade II according to mass spectrometry and western blotting. In immunocytochemistry, we found that COL1A1 expression increases significantly with grades in comparison to control. Similarly, AK2 and PLG also showed little increase but not as much as COL1A1. In flow cytometry, PLG showed higher upregulation in grades than control. While AK2 and COL1A1 showed little increase in expression in grades than control. All techniques, especially mass spectrometry and western blotting, presented higher expression of these proteins in grades as compared to control.

Conclusions:
In the quest to find a suitable therapeutic marker, this study incorporates quantitative labeling and detection followed by flow cytometry, immunocytochemistry, and western blotting for early diagnosis and treatment of meningioma. The article further explores the efficacy of some proteins namely AK2, COL1A1, and PLG to be the targeted molecules.