Expression of centromere protein F (CENP-F) associated with higher FDG uptake on PET/CT, detected by cDNA microarray, predicts high-risk patients with primary breast cancer

Abstract

Background: Higher standardized uptake value (SUV) detected by 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) correlates with proliferation of primary breast cancer. The purpose of this study is to identify specific molecules upregulated in primary breast cancers with a high SUV and to examine their clinical significance.

Methods: We compared mRNA expression profiles between 14 tumors with low SUVs and 24 tumors with high SUVs by cDNA microarray. We identified centromere protein F (CENP-F) and CDC6 were upregulated in tumors with high SUVs. RT-PCR and immunohistochemical analyses were performed to validate these data. Clinical implication of CENP-F and CDC6 was examined for 253 archival breast cancers by the tissue microarray.

Results: The relative ratios of CENP-F and CDC6 expression levels to beta-actin were confirmed to be significantly higher in high SUV tumors than in low SUV tumors (p = 0.027 and 0.025, respectively) by RT-PCR. In immunohistochemical analysis of 47 node-negative tumors, the CENP-F expression was significantly higher in the high SUV tumors (74%) than the low SUV tumors (45%) (p = 0.04), but membranous and cytoplasmic CDC6 expressions did not significantly differ between both groups (p = 0.9 each). By the tissue microarray, CENP-F (HR = 2.94) as well as tumor size (HR = 4.49), nodal positivity (HR = 4.1), and Ki67 (HR = 2.05) showed independent impact on the patients' prognosis.

Conclusion: High CENP-F expression, correlated with high SUV, was the prognostic indicators of primary breast cancer. Tumoral SUV levels may serve as a pretherapeutic indicator of aggressiveness of breast cancer.

Figure 1

The relative expression levels were calculated against the levels of β-actin expression. Mann-Whitney test was performed to confirm the statistical significance of expression levels of CENP-F and CDC6 in breast cancer tissues between patients in low SUV group and those in high SUV group. The bars represent (A) the ratio of the expression level of CENP-F to that of β-actin expression level and (B) the ratio of the expression level of CDC6 to that of β-actin. Empty and filled bars represent a case of the low SUV group and high SUV group, respectively.

Figure 2

CENP-F (A) and Ki67 (D) exhibited immunohistochemically positive staining of nucleus in invasive ductal cancer of the breast. CDC6 revealed 2 patterns of nuclear and cytoplasmic expressions in invasive ductal carcinoma of the breast. Positive nuclear and cytoplasmic stainings of CDC6 are presented in (B) and (C), respectively.

Figure 3

Kaplan-Meier curves of disease-free survival in 253 patients and overall survival in 251 patients with primary breast cancer as having low or high rates of CENP-F positive cancer cells. A cut-off point of 10% positive nuclei was used. The P value was calculated using the log-rank test.

Figure 4

This figure shows the relationship of SUV with breast cancer subtypes including ER+/HER2- (luminal-A) tumors, HER2-overexpressing tumors (HER2 subtype), and ER-/PR-/HER2- (triple-negative, including basal-like and normal breast types) tumors. Only tumors with diameter between 1.5 cm and 2.5 cm were examined. HER2- tumors and triple-negative tumors exhibit higher SUV levels of 5.0 (5.3 SD) and 5.0 (1.9 SD), respectively, compared to luminal-A tumors with SUV of 3.6 (2.7 SD) (p = 0.05 and 0.002, respectively).