Loss of the tumor suppressor PML in human cancers of multiple histologic origins

The PML gene is fused to the RARalpha gene in the vast majority of acute promyelocytic leukemias (APL) and has been implicated in the control of key tumor-suppressive pathways. However, its role in the pathogenesis of human cancers other than APL is still unclear. We therefore assessed the status and expression of the PML gene in solid tumors of multiple histologic origins. We created tumor tissue microarrays (TTMs) with samples from patients with colon adenocarcinoma (n = 109), lung carcinoma (n = 19), prostate adenocarcinoma (n = 36), breast carcinoma (n = 38), central nervous system (CNS) tumors (n = 51), germ cell tumors (n = 60), thyroid carcinoma (n = 32), adrenal cortical carcinoma (n = 12), and non-Hodgkin's lymphoma (n = 251) and from normal tissue corresponding to each histotype and analyzed PML protein and mRNA expression by immunohistochemistry and in situ hybridization, respectively. Tumor cell lines (n = 64) of various histologic origins were analyzed for PML protein and mRNA expression by immunofluorescence and northern blotting, respectively. DNA from microdissected tumor samples and cell lines was analyzed for PML mutations and loss of heterozygosity (LOH). For some tumor types, the association between PML expression and tumor stage and grade was analyzed. Statistical tests were two-sided. All normal tissues expressed PML protein. PML protein expression was reduced or abolished in prostate adenocarcinomas (63% [95% confidence interval [CI] = 48% to 78%] and 28% [95% CI = 13% to 43%], respectively), colon adenocarcinomas (31% [95% CI = 22% to 40%] and 17% [95% CI = 10% to 24%]), breast carcinomas (21% [95% CI = 8% to 34%] and 31% [95% CI = 16% to 46%]), lung carcinomas (36% [95% CI = 15% to 57%] and 21% [95% = 3% to 39%]), lymphomas (14% [95% CI = 10% to 18%] and 69% [95% CI = 63% to 75%]), CNS tumors (24% [95% CI = 13% to 35%] and 49% [95% CI = 36% to 62%]), and germ cell tumors (36% [95% CI = 24% to 48%] and 48% [95% CI = 36% to 60%]) but not in thyroid or adrenal carcinomas. Loss of PML protein expression was associated with tumor progression in prostate cancer (the progression from prostatic intraepithelial neoplasia to invasive carcinoma was associated with complete PML loss; P