Downregulation of miR-204 expression defines a highly aggressive subset of Group 3/Group 4 medulloblastomas

Abstract

Genome-wide expression profiling studies have identified four core molecular subgroups of medulloblastoma: WNT, SHH, Group 3 and Group 4. Molecular markers are necessary for accurate risk stratification in the non-WNT subgroups due to the underlying heterogeneity in genetic alterations and overall survival. MiR-204 expression was evaluated in molecularly classified 260 medulloblastomas from an Indian cohort and in 763 medulloblastomas from the MAGIC cohort, SickKids, Canada. Low expression of miR-204 in the Group 3 / Group 4 tumors identify a highly aggressive subset of tumors having poor overall survival, in the two independent cohorts of medulloblastomas. Downregulation of miR-204 expression correlates with poor survival within the Group 4 as well indicating it as a valuable risk-stratification marker in the subgroup. Restoration of miR-204 expression in multiple medulloblastoma cell lines was found to inhibit their anchorage-independent growth, invasion potential and tumorigenicity. IGF2R was identified as a novel target of miR-204. MiR-204 expression resulted in downregulation of both M6PR and IGF2R that transport lysosomal proteases from the Golgi apparatus to the lysosomes. Consistent with this finding, miR-204 expression resulted in reduction in the levels of the lysosomal proteases in medulloblastoma cells. MiR-204 expression also resulted in inhibition of autophagy that is known to be dependent on the lysosomal degradation pathway and LC3B, a known miR-204 target. Treatment with HDAC inhibitors resulted in upregulation of miR-204 expression in medulloblastoma cells, suggesting therapeutic role for these inhibitors in the treatment of medulloblastomas. In summary, miR-204 is not only a valuable risk stratification marker in the combined cohort of Group 3 / Group 4 medulloblastomas as well as in the Group 4 itself, that has paucity of good prognostication markers, but also has therapeutic potential as indicated by its tumor suppressive effect on medulloblastoma cells. Electronic supplementary material The online version of this article (10.1186/s40478-019-0697-3) contains supplementary material, which is available to authorized users.

The Role of Noncoding RNAs in the Regulation of Anoikis and Anchorage-Independent Growth in Cancer

“…The expression of miR-204-5p is epigenetically silenced in medulloblastoma, and low levels of this miRNA are correlated with the dismal prognosis of patients [ 151 ]. The evaluation of miR-204-5p activity denoted that miR-204-5p reduces the number of cells growing anchorage-independently, at least in part owing to its capability to inhibit autophagy via targeting microtubule-associated proteins 1A/1B light chain 3B (MAP1LC3B, also called LC3B) [ 151 ] ( Figure 2 and Table 2 ).…”

Restoration of miR-193a expression is tumor-suppressive in MYC amplified Group 3 medulloblastoma

“…For the induction of miR-193a expression, the cells were treated with 4 μg/ml doxycycline for 48 h and the expression levels of miR-193a were evaluated by the real-time RT-PCR analysis. The effect of miR-193a expression on the growth and radiation sensitivity of the medulloblastoma cells was studied by the MTT assay as described [17]. The medium containing doxycycline was replenished at 2-day intervals.…”

“…The genes significantly downregulated upon expression of miR-193a in medulloblastoma cells were analyzed for the presence of a miR-193a binding site in their 3′-untranslated regions (3′-UTRs) using the TargetScan software (www.targetscan.org). 3′-UTRs of known miR-193a targets ERBB4, KMT2A, and that of the putative novel targets MAX, DCAF7, STMN1, and MAP3K3 were cloned downstream of the firefly luciferase cDNA in the pcDNA 3.0 vector (Thermo Fischer Scientific, Waltham, MA, USA) and the reporter activity was assayed as described [17]. The miR-193a binding sites in the 3′-UTRs were altered by the site-directed mutagenesis using the overlap extension PCR as described [15].…”

Combined In Situ Hybridization and Immunohistochemistry on Archival Tissues Reveals Stromal microRNA-204 as Prognostic Biomarker for Oral Squamous Cell Carcinoma

“…As an example of putative tumor suppressor miR, miR-204 expression has been shown to decrease in several cancers [ 15 , 16 , 17 , 18 , 19 ]. In favor of its role as a tumor suppressor there are several studies showing anti-tumorigenic effects of miR-204 in both in vitro and in vivo animal studies [ 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. Decreased expression of miR-204 has been associated with poor survival in breast cancer [ 17 ], gastric cancer [ 16 ], endometrial cancer [ 19 ], acute myeloid leukemia [ 22 ], medulloblastoma [ 20 ], and neuroblastoma [ 23 ].…”

“…In favor of its role as a tumor suppressor there are several studies showing anti-tumorigenic effects of miR-204 in both in vitro and in vivo animal studies [ 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. Decreased expression of miR-204 has been associated with poor survival in breast cancer [ 17 ], gastric cancer [ 16 ], endometrial cancer [ 19 ], acute myeloid leukemia [ 22 ], medulloblastoma [ 20 ], and neuroblastoma [ 23 ]. Expression of miR-204 in neuroblastoma cells and gastric cancer cell lines increased their sensitivity to cisplatin [ 23 ], 5-fluorouracil, and oxaloplatin, respectively [ 16 ].…”