Immunohistochemical Analysis of Six1 in Hepatocellular Carcinoma: Correlation with Proliferation, Prognostic Parameters, and Outcome
Jason Wang, Diane Lawson, Cynthia Cohen. Emory University, Atlanta
Background: The incidence of hepatocellular carcinoma (HCC) is increasing, both in the U.S. and worldwide. Homeobox genes encode transcription factors which act as regulators of development. Six1 is one such homeobox gene and is overexpressed in breast, ovarian, hepatocellular, and cervical cancers. Increased Six1 protein expression, detected by Western blot, has been shown to be significantly correlated with pTNM stage, vascular invasion, and poor overall survival.
Design: 135 HCCs in 3 tissue microarrays with 2 1mm cores of each tumor were assessed for Six1 expression by immunohistochemistry (IHC). Stains, scored as intensity 0-3+ and nuclear vs cytoplasmic labeling, were compared to proliferation (mitoses/10HPF, MIB-1 visual mean and high, phosphohistone-3[PPH3] visual mean and high), prognostic parameters (size, grade, stage, vascular invasion, metastases, focality), and outcome (recurrence, survival).
Results: Of the 135 HCCs, 108 (77%) had 2-3+ nuclear Six1 expression, 62 (44%) had 3+ nuclear Six1 expression, 78 (56%) had 2-3+ cytoplasmic Six1 expression, and 30 (21%) had 3+ cytoplasmic Six1 expression.
Significant correlations are summarized below:
|Six1 nuclear (2-3+)||Mitoses||0.001|
|Six1 nuclear (3+)||Size||0.01|
|MIB Visual High||0.001|
|MIB Visual Mean||0.001|
|PPH3 Visual High||0.003|
|PPH3 Visual Mean||<0.001|
|Recurrence||see Figure 1|
|Six1 cytoplasmic (2-3+)||Nuclear Grade||0.04|
|Recurrence||see Figure 2|
|Six1 cytoplasmic (3+)||Size||0.002|
|MIB Visual High||0.03|