TABLE 2.
IMMUNOHISTOCHEMICAL AND GENETIC ANALYSES OF p16 TUMOR SUPPRESSOR GENE INACTIVATION IN PHEOCHROMOCYTOMA TUMOR SPECIMENS
| Specimen* | Expression of p16 Evaluated by IHC† | Genetic Analysis of the p16 Gene | |||
|---|---|---|---|---|---|
| Deletion‡ | Methylation | Point Mutation | Genetic Inactivation | ||
| T1 | P16-low | +/+ | no | no | no |
| T2 | P16-negative | +/+ | no | no | no |
| T3 | P16-low | +/+ | no | no | no |
| T4 | P16-negative | +/− | no | no | yes |
| T5 | P16-low | +/− | no | no | yes |
| T6 | P16-negative | +/+ | no | no | no |
| T7 | P16-low | +/− | no | no | yes |
| T8 | P16-low | +/+ | no | no | no |
| T9R§ | P16-low | +/+ | no | no | no |
| T9L§ | P16-negative | +/+ | yes | no | yes |
| T10 | P16-low | +/+ | yes | no | yes |
| T11 | P16-low | −/− | no | no | yes |
| T12 | P16-negative | +/− | no | no | yes |
| T13 | P16-negative | −/− | no | no | yes |
| T14 | P16-low | +/+ | yes | no | yes |
| T15 | P16-negative | +/+ | yes | no | yes |
| T16R§ | P16-low | +/+ | no | no | no |
| T16L§ | P16-high | +/+ | no | Ala 20 (GCT)/Pro (CCT) | yes |
| T17 | P16-negative | +/+ | yes | no | yes |
| T18R§ | P16-negative | −/− | no | no | yes |
| T18L§ | P16-low | +/+ | yes | no | yes |
| T19 | P16-negative | +/+ | yes | no | yes |
| T20 | P16-negative | +/− | no | no | yes |
| T21 | P16-low | −/− | no | no | yes |
| T22 | P16-negative | +/+ | no | no | no |
| T23 | P16-negative | +/+ | no | no | no |
| T24R§ | P16-low | +/+ | no | no | no |
| T24L§ | P16-low | +/+ | yes | no | yes |
| T25 | P16-low | +/+ | yes | no | yes |
| T26 | P16-low | +/+ | yes | no | yes |
| T27 | P16-low | +/+ | yes | no | yes |
| C3 | P16-high | +/+ | no | no | no |
| C4 | P16-low | +/+ | no | no | no |
| C9R | P16-high | +/+ | no | no | no |
| C9L | P16-high | +/+ | no | no | no |
| C22 | P16-high | +/+ | no | no | no |
| C25 | P16-high | +/+ | no | no | no |
| C27 | P16-low | +/+ | no | no | no |
*
T and C represent tumor and control “normal” specimens, respectively.
†
IHC immunohistochemistry. Based on the percentage of positive nuclear P16 staining by immunohistochemis-try, the samples were categorized as P16-negative (complete absence of nuclear immunostaining), P16-low (1–25% of positive nuclei) or P16-high (>25% of positive nuclei), as previously described.
‡
+/+ wild-type, +/− hemizygous deletion, −/− homozygous deletion.
§
R: right-sided tumor, L: left-sided tumor.