The expression pattern of small nucleolar and small cajal body-specific RNAS characterizes distinct molecular subtypes of multiple myeloma

Small nucleolar RNAs (snoRNAs) and small Cajal body-specific RNAs (scaRNAs) are non-coding RNAs involved in the maturation of other RNA molecules and generally located in the introns of host genes. It is now emerging that altered snoscaRNAs expression may have a pathological role in cancer. This study elucidates the patterns of snoscaRNAs expression in multiple myeloma (MM) by profiling purified malignant plasma cells from 55 MMs, 8 secondary plasma cell leukemias (sPCLs) and 4 normal controls. Overall, a global snoscaRNAs downregulation was found in MMs and, even more, in sPCLs compared with normal plasma cells. Whereas SCARNA22 resulted the only snoscaRNA characterizing the translocationcyclin D4 (TC4) MM, TC2 group displayed a distinct snoscaRNA signature overexpressing members of SNORD115 and SNORD116 families located in a region finely regulated by an imprinting center at 15q11, which, however, resulted overall hypomethylated in MMs independently of the SNORD115 and SNORD116 expression levels. Finally, integrative analyses with available gene expression and genome-wide data revealed the occurrence of significant snoscaRNAshost genes co-expression and the putative influence of allelic imbalances on specific snoRNAs expression. Our data extend the current view of snoscaRNAs deregulation in cancer and add novel information to the bio-molecular complexity of plasma cell dyscrasias.