Abstract
BackgroundATP-binding cassette sub-family G member 2 (ABCG2) is a semi-transport protein that plays a major role in multidrug resistance. We aimed to evaluate the prognostic significance of ABCG2 expression in patients with clear cell renal cell carcinoma.MethodsFrom 2008 to 2013, 120 patients with clear cell kidney cancer underwent surgery with paraffin-embedded specimens and necessary clinical information available. Immunohistochemistry staining was performed to grade the expression of ABCG2 as ABCG2(−): less than 10% of tumor cells stained; ABCG2(+): weak membrane staining; and ABCG2(++): moderate or strong membrane staining. The overall survival was analyzed using Kaplan-Meier method. Multivariable Cox regression evaluated the independent predictors for overall survival.ResultsABCG2(−) was diagnosed in 57 (48%) patients, ABCG2(+) in 52 (43%) patients, and ABCG2 (++) in 11(9.2%) patients. ABCG2 expression significantly correlated with the five-year survival (p < 0.001) and distant metastasis (p = 0.001). In the multivariable analysis, besides Fuhrman grade, the ABCG2 expression was an independent prognostic marker for overall survival (p < 0.001) when incorporating other relevant tumor and clinical parameters (HR = 3.84, 95% CI: 1.92–7.70).ConclusionThe current data suggests that ABCG2 may serve as a prognostic marker for overall survival in patients with clear cell renal cell carcinoma. Further studies with large cohorts of patients will be essential for validating these findings and defining the clinical utility of ABCG2 in the patient population.
Highlights
ATP-binding cassette sub-family G member 2 (ABCG2) is a semi-transport protein that plays a major role in multidrug resistance
In order to explore the expression of ABCG2 in non-Renal cell carcinoma (RCC) tissue, we examined another 10 hydronephrosis patients with noncancer renal tissue and found that ABCG2 was negative in these non-cancer renal parenchyma samples
ABCG2 expression in metastasis cohort We found ABCG2 expression significantly associated with distant metastasis on first diagnosis (p = 0.001) (Table 2)
Summary
ATP-binding cassette sub-family G member 2 (ABCG2) is a semi-transport protein that plays a major role in multidrug resistance. Renal cell carcinoma (RCC) is the most common type of malignant renal cancer in adults, responsible for approximately 90–95% of the diagnosed cases [1]. Surgery is the primary treatment for RCC, and the five-year survival rate is 65–90%; the outcome is considerably reduced in metastatic cases [3]. RCC is relatively resistant to radiotherapy and chemotherapy with only a 4–5% response rate [4, 5]. ATP-binding cassette sub-family G member 2 (ABCG2) was first named as Breast Cancer Resistance Protein in the 1990s when it was discovered in MCF-7 breast cancer cell line co-selected for doxorubicin in the presence of verapamil [9].
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