Gene Expression of TGF-α, EGF and IL-6 in Cultured Renal Tubular Cells and Renal Cell Carcinoma

Background: Renal cell carcinoma (RCC) is thought to arise from the renal tubular cells (RTC). Assuming that proliferating RTC imply a premalignant change of RTC into RCC, messenger RNA expressions of growth factors in cultured RTC were compared to both cultured and frozen noncultured RCC.
Methods: The expression of transforming growth factor-alpha (TGF-α), epidermal growth factor (EGF), EGF receptor (EGFR) and Interleukin-6 (IL-6) were studied in surgically obtained RCC (n=17), cultured RCC (n=10), and autologous cultured RTC (n = 15). Quantitation of the PCR product was performed using a computer image analyzer which evaluated the intensity of each cytokine relative to β-actin.
Results: TGF-α, EGFR and IL-6 were detected in most of the cultured RTC, and both cultured and noncultured RCC were also expressed at high levels. In contrast to a high positivity of TGF-α, EGF was not strongly positive in all specimens.
Conclusions: Our results show that there is a predominant autocrine production of TGF-α in RCC and RTC, suggesting that TGF-α plays a distinct role in the proliferation of these cells. These studies also indicate that the mechanisms of proliferation and cytokine production of RCC and RTC are similar.