Expression of interferon-gamma in human adrenal gland and kidney tumours

Abstract

It is known that interferon-gamma (IFN-gamma) is produced by activated T and NK lymphoid cells, mononuclear cells, and macrophage and dendritic cells. Our previous studies have shown that IFN-gamma-like immunoreactivity also appears in human adrenal cortical tumour and phaeochromocytoma. To investigate whether human tumour cells can produce IFN-gamma, we examined 429 biopsy specimens of 30 kinds of tumour and tumour-surrounding tissues in adrenal glands and in kidneys by using immunohistochemistry and in situ hybridisation. IFN-gamma immunoactivity was shown in 34.3% of the adrenal cortical adenomas, 50% of the adrenal cortical carcinomas, 26.7% of the phaeochromocytomas, 26.7% of the clear cell renal cell carcinomas (RCCs), 22% of the adrenal cortexes and 40% of medullas adjacent to tumours. The positive samples and expression areas were well overlapped between the IFN-gamma mRNA and the immunohistochemistry staining. Western blot analysis has further confirmed the immunohistochemistry results by showing a distinct IFN-gamma band corresponding to 17.4 kDa in tissue extracts from adrenal cortical adenoma, phaeochromocytoma and clear cell RCCs. These results indicate that IFN-gamma is produced by some types of tumour cells, suggesting it may play a dual role in the development of these tumours.

Figure 1

IFN-γ immunoreactivity in (A) adrenal cortical adenoma, (B) cortical carcinoma, (C) phaeochromocytoma, (D) clear cell RCC, tumour adjacent tissue in (E) adrenal cortex (F) and medulla. The immunoreactive IFN-γ-positive cells show distinct brown staining. The immunoreactive materials often appear as densely packed granules filling the entire or focal of cytoplasm of tumour cells (arrow) and the interstitial tissue is negative (arrowhead). No IFN-γ immunoreactivity is seen in (G) kidney. Clear cell RCC (same case as in D) matched (H) negative control staining do not show any positive staining. Bar=50 μm.

Figure 2

In situ hybridisation for IFN-γ mRNA. The IFN-γ mRNA signals are seen in adrenal (A) cortical adenoma, (B) cortical carcinoma, (C) phaeochromocytoma, (D) clear cell RCC, tumour adjacent tissue (E) in adrenal cortex (F) and medulla. IFN-γ mRNA is apparent in the cytoplasm of parenchyma cells (arrow), not in interstitial tissue (arrowhead). IFN-γ mRNA signals are not seen in HCC (G). Adrenal cortical carcinoma (same case as in B) matched negative control with (H) mRNase do not show any positive staining. Bar=50 μm.

Figure 3

Western blot analysis for IFN-γ. A 17.4 kDa IFN-γ protein band appears in the extracts from adrenal cortical adenomas (lanes 1 and 2), clear cell RCC (lane 3) and pheochromocytoma (lane 4). Negative control (lane 5, same case as in lane 1) and colonic adenocarcinoma (lane 6) do not show any band.