Cytokines in Renal Cell Carcinoma : With emphasis on Vascular Endothelial Growth Factor (VEGF) and Interleukin 6 (IL-6)

Abstract

Aims: In the first three papers we aimed to investigate if different circulating cytokines in blood drawn preoperatively can predict outcome after surgery in patients with renal cell carcinoma (RCC). The last paper aimed to evaluate the volatility of different cytokines and their receptors before, during and after surgery.

Material and Methods: In the three first studies (paper I-III), we used data from our kidney cancer database at Haukeland University Hospital. From the database, we identified 159 patients treated with partial, radical or a cyto-reductive nephrectomy at our institution between January 2007 and March 2010, who had signed informed consent forms and a preoperative drawn frozen blood sample were available. In the last study (paper IV), 40 patients with renal tumors who were scheduled for open surgery with partial or radical nephrectomy were prospectively included between April 2018 and June 2019. Blood samples were taken pre-operatively, intra- operatively (simultaneously from the renal vein (RV) and a peripheral vein) and at control 4-6 weeks post-surgery. The blood samples in all papers were analyzed and cytokines detected and measured using Luminex immune-bead technology and high-sensitivity kit from Invitrogen/Biosource. In paper I-III, the patients were followed up until death or the end of each study period.

Results: In paper I, a high level of circulating VEGF were an independent predictor (p=0.017) for cancer specific survival (CSS) in a multivariate analysis. Furthermore, VEGF together with the well-established prognostic factors tumor T-stage and nuclear grade, predicted disease recurrence in patients presumed to be radically treated (p=0.03, p=0.011 and p=0.008, respectively). In paper II, a high level of IL-6 and IL-27 predicted disease recurrence in presumed radically treated patients (p=0.001 and p=0.026, respectively). In particular, the predictions among patients with large tumors (>7 cm) were excellent for both IL-6 and IL-27 (p=0.014 and p=0.001, respectively). In paper III, higher circulating levels of IL-33Rα are associated with worse prognosis (p=0.034). However, the demonstrated impact of IL-33Rα was dependent on the overall cytokine profile, including seven IL6 family members (IL-6, IL-6Rα, gp130, IL-27, IL-31, CNTF, and OSM), two IL-1 subfamily members (IL-1Rα and IL-33Rα), and TNFα. In paper IV, among clear-cell RCC patients, the intraoperative RV concentration of IL-6 was significantly higher than in both the pre- and postoperative samples (p=0.005 and p=0.032, respectively). Furthermore, the intraoperatively ratio between the RV and the peripheral sample differed significantly from the expected value of 1, indicating that at least a fraction of the increased IL-6 levels intraoperatively originates from the tumor cells or the tumor environment. Other cytokines and receptors remained stable across all measurements.

Conclusions: In paper I, preoperative high levels of circulating VEGF predicted both an increased risk of disease recurrence and a worse CSS. In paper II, among presumed radically treated RCC patients, higher levels of circulating IL-6 and IL-27, predicted both disease recurrence and impaired CSS. In paper III, based on differences in the overall acute phase cytokine profile, we were able to classify RCC patients into two main subsets that differed significantly with regard to prognosis. In addition, a high IL-33Rα predicted worse survival. In paper IV, while most cytokines and receptors remained remarkably stable, serum levels of IL-6 increased during renal tumor surgery. This increase may at least in part be attributed to the RCC tumor cells or the immediate tumor environment. In conclusion, the studied cytokines seem to play an important biological role in RCC and may be useful for outcome prediction in RCC patients.