Metastasis Associated in Colorectal Cancer 1 (MACC1) mRNA Expression Is Enhanced in Sporadic Vestibular Schwannoma and Correlates to Deafness

SIMPLE SUMMARY: Vestibular schwannoma (VS), benign cranial nerve sheath tumors of the vestibulocochlear nerve, lack efficacious systemic therapies, especially if they develop in a NF2-related schwannomatosis (NF2) background. They cause hearing loss, tinnitus and balance problems. Metastasis associated in colon cancer 1 (MACC1) is a key driver of metastasis. Although MACC1 expression is associated with highly malignant tumors and VS are considered benign, both are attached to the HGF/MET signaling pathway and MACC1 is a candidate gene localized at a hearing loss-related gene locus. Therefore, it was investigated whether MACC1 might be involved in VS pathogenesis. Surprisingly, MACC1 expression was not increased in the more aggressive NF2-associated VS but in sporadic VS. Its expression correlated with deafness of the patients during their clinical course. Thus, these data are a rationale for further investigation of the putative role of MACC1 in VS pathogenesis, especially VS cell invasion and concomitant deafness of patients. ABSTRACT: Vestibular schwannoma (VS) are benign cranial nerve sheath tumors of the vestibulocochlear nerve. Their incidence is mostly sporadic, but they can also be associated with NF2-related schwannomatosis (NF2), a hereditary tumor syndrome. Metastasis associated in colon cancer 1 (MACC1) is known to contribute to angiogenesis, cell growth, invasiveness, cell motility and metastasis of solid malignant cancers. In addition, MACC1 may be associated with nonsyndromic hearing impairment. Therefore, we evaluated whether MACC1 may be involved in the pathogenesis of VS. Sporadic VS, recurrent sporadic VS, NF2-associated VS, recurrent NF2-associated VS and healthy vestibular nerves were analyzed for MACC1 mRNA and protein expression by quantitative polymerase chain reaction and immunohistochemistry. MACC1 expression levels were correlated with the patients’ clinical course and symptoms. MACC1 mRNA expression was significantly higher in sporadic VS compared to NF2-associated VS (p < 0.001). The latter expressed similar MACC1 concentrations as healthy vestibular nerves. Recurrent tumors resembled the MACC1 expression of the primary tumors. MACC1 mRNA expression was significantly correlated with deafness in sporadic VS patients (p = 0.034). Therefore, MACC1 might be a new molecular marker involved in VS pathogenesis.