Loss of the Orphan Nuclear Receptor SHP Is More Pronounced in Fibrolamellar Carcinoma than in Typical Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) remains a major problem in oncology. The molecular mechanisms which underlie its pathogenesis are poorly understood. Recently the Small Heterodimer Partner (SHP), an orphan nuclear receptor, was suggested to be involved as a tumor suppressor in hepatocellular carcinoma development. To date, there are no such studies regarding fibrolamellar carcinoma, a less common variant of HCC, which usually affects young people and displays distinct morphological features. The aim of our project was to evaluate the SHP levels in typical and fibrolamellar hepatocellular carcinoma with respect to the levels of one of the cell cycle regulators, cyclin D1. We assessed the immunoreactivity levels of SHP and cyclin D1 in 48 typical hepatocellular carcinomas, 9 tumors representing the fibrolamellar variant, 29 non malignant liver tissues and 7 macroregenerative nodules. We detected significantly lower SHP immunoreactivity in hepatocellular carcinoma when compared to non malignant liver tissue. Moreover, we found that SHP immunoreactivity is reduced in fibrolamellar carcinoma when compared to typical hepatocellular carcinoma. We also found that SHP is more commonly lost in HCC which arises in the liver with steatosis. The comparison between the cyclin D1 and SHP expression revealed the negative correlation between these proteins in the high grade HCC. Our results indicate that the impact of loss of SHP protein may be even more pronounced in fibrolamellar carcinoma than in a typical form of HCC. Further investigation of mechanisms through which the loss of SHP function may influence HCC formation may provide important information in order to design more effective HCC therapy

SHP immunoreactivity in normal liver.

<p>A, B – immunohistochemical staining of the normal hepatic lobule; C, D- immunofluorescence staining showing exclusively nuclear (C) or cytoplasmic (D) SHP localization in different lobules; scale bar: A 100 µm; B 20 µm; C,D 25 µm. E- result of the SHP immunohistochemistry preceded with (lower image) or without (upper image) anti-SHP blocking antibody; F- Western blot analysis of three liver (LV1–LV3) lysates, the SHP protein present in a single band; G- Result of the RT-PCR study showing the SHP mRNA in the normal liver; GAPDH mRNA was used as a control.</p

The cyclin D1 expression in hepatocellular carcinoma.

<p>A- the immunoreactivity of cyclin D1 in HCC tumor; B- the cyclin D1 immunoreactivity in fibrolamellar carcinoma; scale bar 5 µm; C- Spearman's rank graph showing a negative correlation between the SHP and cyclin D1 immunoreactivity in G3 hepatocellular carcinoma.</p

SHP immunoreactivity in macroregenerative nodules.

<p>Note uniform staining of all hepatocytes; scale bar A-100 µm, B-50 µm.</p

Clinicopathological characteristic of patients with results of the immunostaining.

<p>Abbreviations: Ca cm maximal tumor size in cm; Inflamm inflammation; G tumor grade; S stage; N normal; C cirrhosis; R HCC recurrence;</p><p>*data not available; n/a not applicable.</p