In
colorectal cancer (CRC) with
microsatellite instability (MSI), >90% of cases are affected by inactivating frameshift mutations of
transforming growth factor β receptor type 2 (
TGFBR2).
TGFBR2 deficiency is considered to drive MSI
tumor progression by abrogating downstream TGF‑β signaling. This pathway can alter the expression of coding and non‑coding RNAs, including
microRNAs (
miRNAs), which are also present in extracellular vesicles (EVs) as post‑transcriptional modulators of gene expression. In our previous study, it was shown that
TGFBR2 deficiency alters the
protein composition and function of EVs in MSI
tumors. To investigate whether mutant
TGFBR2 may also affect the
miRNA cargo of EVs, the present study characterized
miRNAs in EVs and their parental MSI
tumor cells that differed only in
TGFBR2 expression status. The HCT116‑TGFBR2 MSI cell line model enables the
doxycycline (dox)‑inducible reconstituted expression of
TGFBR2 in an isogenic background (‑dox,
TGFBR2 deficient; +dox,
TGFBR2 proficient). Small
RNA sequencing of cellular and EV
miRNAs showed that the majority of the
miRNAs (263/471; 56%) were shared between MSI
tumor cells and their EVs. Exploratory data analysis revealed the TGBFR2‑dependent cluster separation of
miRNA profiles in EVs and MSI
tumor cells. This segregation appeared to result from two subsets of
miRNAs, the expression of which were regulated in a TGFBR2‑dependent manner (EVs: n=10; MSI cells: n=15). In the EV subset, 7/10
miRNAs were downregulated and 3/10 were upregulated by
TGFBR2 deficiency. In the cellular subset, 13/15
miRNAs were downregulated and 2/15
miRNAs were upregulated in the TGFBR2‑deficient cells. The present study emphasizes the general overlap of
miRNA profiles in MSI
tumor cells and their EVs, but also highlights the impact of a single
tumor driver mutation on the expression of individual
miRNAs, as exemplified by the downregulation of miR‑381‑3p in TGFBR2‑deficient MSI
tumor cells and their secreted EVs.