Downregulation of lncRNA-MALAT1, Altered Immunohistochemical Expression of Cyclin D1 Protein and E-Cadherin Protein in Correlation to Meningioma Grades.

Objectives: Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is known to be upregulated in the tumors with ability to metastasize. In contrast, long non-coding Ribonuclei acid (lncRNA) MALAT1 was reported by some studies to be downregulated in meningioma cells.  E-cadherin and Cyclin D1 are prognostic indicators and possible attractive targets for the treatment of recurring and aggressive meningioma. This study aimed to evaluate the expression level of lncRNA MALAT1, as well as Cyclin D1 and E-cadherin immunohistochemical expression in meningiomas (Grade 1 and 2) and their association with the clinicopathological parameters of the studied cases.

Material And Methods: Quantitative determination of relative expression levels of lncRNA-MALAT1 in 64 cases of meningioma to 5 controls of normal dura mater was performed, in addition to evaluation of E-cadherin and Cyclin D1 immunohistochemical expression. The results were tested for association with the clinicopathological parameters.

Results: lncRNA-MALAT1 expression were downregulated in 49/64 of the cases of meningioma (76%) in comparison to control. There were significant association of expression of lncRNA-MALAT1 with grade, brain invasion and increased mitosis (p=0.007, 0.04, 0.006 respectively). There were also significant associations of strong E-cadherin and negative Cyclin D1 proteins expression with grade 1 (p = 0.02, 0.004), low mitosis (p=0.03, and 0.04) and brain invasion (p=0.04, 0.03) respectively. Additionally, a significant weak negative correlation between E-cadherin and Cyclin D1 expression was fond, yet no significant correlation between lncRNA MALAT1 expression and either of E-cadherin or Cyclin D1 expression could be achieved.

Conclusion: lncRNA MALAT1 is downregulated in meningiomas and associated with increased aggressiveness. Overexpressed cyclin D1 and decreased E-cadherin expression are also associated with high grade meningioma.