Transcriptome of Breast Tumors With Different Amplification Status of the Long Arm of Chromosome 8.

Background: Amplification of chromosome 8q with locus 8q24 is the most common copy number aberration, and is associated with tumour progression and chemoresistance.

Materials And Methods: The study used paired samples of biopsy and surgical material from 60 patients with breast cancer. The amplification status of 8q was determined using a CytoScan HD Array microarray; complete transcriptomic analysis was performed using a Human Clariom S Assays microarray (Affymetrix, USA).

Results: It was shown that in 65% of cases, amplification of 8q was preserved in the tumour after neoadjuvant chemotherapy (NAC). NAC significantly enhanced the heterogeneity of the transcriptome between tumours with and without amplification of 8q. Compared with a good response, a poor response to NAC also led to increased heterogeneity of the transcriptome of residual tumours. Eight differentially expressed genes of patients with different amplification status of 8q before and after NAC overlapped.

Conclusion: Amplification of 8q leads to a significant shift in the level of transcription of a large number of genes after exposure to chemotherapy.