Discrepancy Between Clinical Diagnosis and Whole-exome Sequencing-based Clonality Analysis of Synchronous Multiple Oral Cancers.

BACKGROUND/AIM: The definition of multiple oral cancers is based on the distances between the tumors. However, it is not possible to accurately predict tumor origins based only on clinical criteria. PATIENTS AND METHODS: We performed whole-exome sequencing (WES) to analyze the genetic alterations in five tumors of two patients who underwent surgery in our hospital. RESULTS: In case 1, the distances between tumors on the right mandibular gingiva and buccal mucosa were more than 15 mm, leading to a clinical diagnosis of multiple primary tumors. WES revealed common mutations between tumors, suggesting that the tumors were derived from the same clone. In contrast, in case 2, the distance between tumors on the right side of the tongue was only 10 mm, but the tumors were diagnosed as double primary tumors because their mutations were completely different. CONCLUSION: WES, rather than the available clinical criteria, can clarify the clonal origins of multiple oral cancers.

miR-1293, a Candidate for miRNA-Based Cancer Therapeutics, Simultaneously Targets BRD4 and the DNA Repair Pathway.

BRD4, a member of the bromodomain and extra-terminal domain (BET) protein family, plays a role in the organization of super-enhancers and transcriptional activation of oncogenes in cancer and is recognized as a promising target for cancer therapy. microRNAs (miRNAs), endogenous small noncoding RNAs, cause mRNA degradation or inhibit protein translation of their target genes by binding to complementary sequences. miRNA mimics simultaneously targeting several tumor-promoting genes and BRD4 may be useful as therapeutic agents of tumor-suppressive miRNAs (TS-miRs) for cancer therapy. To investigate TS-miRs for the development of miRNA-based cancer therapeutics, we performed function-based screening in 10 cancer cell lines with a library containing 2,565 human miRNA mimics. Consequently, miR-1293, miR-876-3p, and miR-6571-5p were identified as TS-miRs targeting BRD4 in this screening. Notably, miR-1293 also suppressed DNA repair pathways by directly suppressing the DNA repair genes APEX1 (apurinic-apyrimidinic endonuclease 1), RPA1 (replication protein A1), and POLD4 (DNA polymerase delta 4, accessory subunit). Concurrent suppression of BRD4 and these DNA repair genes synergistically inhibited tumor cell growth in vitro. Furthermore, administration of miR-1293 suppressed in vivo tumor growth in a xenograft mouse model. These results suggest that miR-1293 is a candidate for the development of miRNA-based cancer therapeutics.