6p22.3

amp(6)(p22)

Medium-to-high-level genomic amplification sometimes resulting in HSR formation and believed to target E2F3 which lies within the common amplified region (see image below). Genomic amplification may not be required for over-expression.

Notably, bladder and prostate cancers.

Associated with invasiveness in bladder cancer, and with poor survival in prostate cancer. Circa 33% of primary transitional cell carcinomas of the bladder overexpress nuclear E2F3 protein.

Presumptive target of genomic amplification at 6p22 in bladder cancer where it effects E2F3 overexpression (as exemplified by the bladder cancer cell lines 5637 and HT-1367). However, E2F3 may not be the only target gene inside the common amplified region.

Not yet reported

t(6;9)(p22;p13)

Observed in a DLBCL cell line: yet to be described clinically.

Diffuse large B-cell lymphoma (DLBCL).

Unknown

Breakpoint lies upstream of E2F3 and juxtaposes upstream (regulatory) region of PAX5.

Not yet reported

E2F3 behaves like a classical oncogene and is subject to upregulation via genomic amplification in bladder and prostate cancers. Upregulated E2F3 stimulates cycle progression and proliferation. E2F3 transcription is induced by MYC and these together conspire to promote G1/S-phase transition. This activity is negatively regulated by binding of the E2F transactivation domain to RB1 or p107. In prostate cancer, oncogenesis directed by E2F3 may be mediated by the polycomb group protein Enhancer of Zeste Homolog gene 2 (EZH2). E2F3 may also activate survivin transcription.
In Hodgkin lymphoma which, though lacking recurrent chromosomal rearrangements at 6p22, shows a pattern of gene dysregulation reminiscent of prostate cancer, E2F3 regulates HLXB9 expression which in turn drives IL-6 expression thought to play a central role in this enigmatic tumor.
E2F3 may also act as a tumor suppressor though the supporting evidence is tentative. Thus, while E2F3 loss results in centrosome defects associated with aneuploidy and promotes metastasis of medullary thyroid carcinoma, E2F3 -/- mice show no excess tumor incidence. Furthermore, loss of E2F3 has been associated with suppression of pituitary tumors.