Off-target messenger RNAs with partial complementarity to B7 homolog 3 (B7-H3) short hairpin RNA seed region

Off-target messenger RNAs with partial complementarity to B7 homolog 3 (B7-H3) short hairpin RNA (shRNA) seed region refer to a diverse set of unintended genetic transcripts that are downregulated during the use of RNA interference (RNAi) tools directed against B7-H3 (CD276). This phenomenon is driven by the 'seed region' of the shRNA guide strand (nucleotides 2–8), which can bind to the 3' untranslated regions (UTRs) of non-target mRNAs with partial complementarity, mimicking the action of endogenous microRNAs (Jackson et al., 2003; Birmingham et al., 2006). B7-H3 is a member of the B7 family of immunoregulatory proteins and is a significant target in oncology due to its overexpression in various solid tumors and its role in inhibiting T-cell mediated immune responses (NCBI Gene ID: 80381). However, research utilizing shRNAs to knock down B7-H3 has often encountered 'off-target toxicity,' where the observed phenotypic changes—such as reduced cell proliferation or increased apoptosis—are actually caused by the unintended silencing of these off-target mRNAs rather than the loss of B7-H3 itself (Lin et al., 2019). This highlights a critical challenge in functional genomics and the development of RNAi-based therapeutics, necessitating rigorous validation through rescue experiments or the use of multiple independent shRNA sequences to ensure specificity. These off-target interactions are not therapeutic goals but represent technical artifacts that can lead to false-positive results in drug target validation studies.

Other names

Seed-sequence-dependent off-targetsRNAi off-target effectsmiRNA-like off-target silencingB7-H3 shRNA off-targets

Unintended sequence-specific downregulation of mRNAs via the RNA-induced silencing complex (RISC) triggered by seed-region complementarity in the 3' UTR.