Highly sensitive and specific hybridization assay for quantification of mRNA in mantle cell lymphoma reveals association of mutations with negative and low expression.

SOX11 is a valuable marker to identify biologically and clinically relevant groups of mantle cell lymphoma such as cyclin D1 negative and leukemic non-nodal mantle cell lymphoma (MCL). We aimed to establish a sensitive hybridization analysis of mRNA allowing its quantification within the histopathological context and compare it with immunohistochemistry and real-time quantitative reverse transcription-PCR (RT-qPCR). Furthermore, status was correlated with mRNA levels. Sixty-six cases were investigated; 58 conventional mantle cell lymphomas (cMCL), including six cyclin D1 negative (46 classic, 12 blas-toid) and eight leukemic non-nodal mantle cell lymphomas (nnMCL). RNAscope was used for the hybridization and the results scored as 0 to 4. MCL cases with SOX11 positivity by immunohistochemistry (IHC) were positive by RNA hybridization (RNAscope) but with different scores. RT-qPCR showed a good correlation with the median of the grouped scores but had a wide variation in individual cases. The SOX11 negative leukemic non-nodal mantle cell lymphomas were also negative by RNAscope. was mutated in 13/63 (21%) cases, including 5/7 (71%) leukemic non-nodal and 8/56 (14%) cMCL. Interestingly, of the mutated cases, nine were in the RNAscope negative/low SOX11 group (9/15; 60%) and four in the high SOX11 group (4/36; 11%) (=0.0007). In conclusion, RNAscope is a reliable method to evaluate mRNA levels. This study demonstrates the broad range of mRNA levels in MCL. An important finding is the significant correlation of mutations with negative/low mRNA level both in leukemic nnMCL and cMCL.