Prothymosin-alpha mRNA expression correlates with that of c-myc in human colon cancer.

Prothymosin alpha (PT-alpha) is a nuclear protein involved in cell proliferation. Transcription of PT-alpha has been reported to be regulated by the c-myc gene in vitro. We identified PT-alpha as being overexpressed in a human colon cancer minus normal mucosa subtraction cDNA library. Northern blot (messenger RNA) analysis showed that both PT-alpha and c-myc genes were overexpressed in human colorectal cancers compared with adjacent normal tissues. Immunohistochemical studies for PT-alpha and c-myc supported these findings. There was no correlation between PT-alpha or c-myc messenger RNA expression and Dukes' stage of colorectal cancer; or between either of these two and actin messenger RNA expression. There was, however, a significant correlation between the PT-alpha expression and c-myc expression (P < 0.001). These findings support the hypothesis that PT-alpha gene transcription may be associated with, and possibly under the control of, the c-myc gene in human colorectal cancers.