Altered PTEN function caused by deletion or gene disruption is associated with poor prognosis in rectal but not in colon cancer

作者：Bohn B A; Mina S; Krohn A; Simon R; Kluth M; Harasimowicz S; Quaas A; Bockhorn M; Izbicki J R; Sauter G; Marx A; Stahl P R^*

来源：Human Pathology, 2013, 44(8): 1524-1533.

DOI：10.1016/j.humpath.2012.12.006

• PTEN phosphohydrolase
• Colorectal neoplasms
• Fluorescence in situ hybridization
• Gene deletion

Colorectal cancer is the third most common malignancy worldwide. Anti-epidermal growth factor receptor (EGFR)-targeted therapy shows clinical evidence in this malignancy and improves outcome. The tumor suppressor gene phosphatase and tensin homologue (PTEN) is considered a potential predictor of nonresponse to anti-EGFR agents. The purpose of this study was to assess whether associations between PTEN alterations (PTEN gene deletion or PTEN gene disruption) and clinical outcome could be caused by a prognostic (and not predictive) effect of PTEN inactivation. Therefore, we analyzed 404 colorectal cancers not previously treated with anti-EGFR drugs in a tissue microarray format. PTEN deletion and PTEN gene rearrangements were analyzed by fluorescence in situ hybridization. Heterogeneity analysis of all available large tissue sections was performed in 6 cases with genomic PTEN alteration. Twenty-seven (8.8%) of 307 analyzable colorectal cancer spots showed genomic PTEN alterations including 24 hemizygous and 1 homozygous deletion as well as 2 PTEN gene disruptions. Genomic PTEN alterations were associated with reduced patient survival in rectal cancer in univariate and multivariate analyses (P = .012; hazard ratio, 2.675; 95% confidence interval, 1.242-5.759) but not in colon cancer. Large-section evaluation revealed a homogeneous distribution pattern in all 4 analyzed cases with PTEN deletion and in both cases with a PTEN gene disruption. In conclusion, genomic PTEN gene alterations caused by deletion or gene disruption characterize a fraction of rectal cancers with particularly poor outcome.

• 出版日期2013-8