[1006] Immunohistochemical Profile of Stem/Progenitor Cell Marker C133 in Variants of Renal Tumors

John D Schwartz, Mitual B Amin, Ping L Zhang. William Beaumont Hospital, Royal Oak, MI; Oakland University William Beaumont School of Medicine, Rochester, MI

Background: CD133, a stem/progenitor cell marker, is expressed diffusely in normal glomerular parietal epithelium (GPE) as well as in a small percent of normal renal tubular epithelium. Cancer stem cells have been proposed to undergo malignant transformation from benign stem cells, since only stem cells may carry sufficient genetic properties for unlimited tumor proliferation. The intent of this study was to investigate the immunohistochemical expression of CD133 in variants of renal tumors.
Design: Seven groups of renal tumors (n = 84, tumor cross sections) were immunohistochemically stained for CD133 (monoclonal AC133 antibody at 1:20 and rabbit polyclonal CD133 antibody at 1:500, in order to achieve similar positivity in normal GPE). The percent of membranous CD133 expression in tumor cells was graded as follows: 1+ <33%, 2+, 33-66% and 3 + >66%.
Results: Using monoclonal CD133, diffuse membranous positivity was found in clear cell papillary renal cell carcinoma (CCP-RCC) (10/10, 100%, 3+ in 8, 2+ in 1 and 1+ in 1) (Panel A), and often in XP11.2 translocation carcinoma (5/9, 56%, 3+ in 1, 2+ in 1 and 1+ in 3) and papillary RCC (8/15, 53%, 3+ in 2, 2+ in 1 and 1+ in 5). CD133 was also expressed in a small percent of Wilms' tumor (4/14, 28%, 1+ in epithelial component of 4 cases), clear cell RCC (3/21, 14%, 3+ in 1 and 1+ in 2), chromophobe RCC (1/7, 14%, 1+ in 1), and oncocytoma (1/5, 20%, 1+ in 1). Polyclonal CD133 staining confirmed the above findings. Stem cell transcription factor OCT3/4 staining revealed nuclear positivity in 9/10 CCP-RCC (90%, 3+ in 4, 2+ in 4, 1+ in 1 and 0 in 1) (Panel B) but it was rarely positive in the remaining types of renal tumors.

Conclusions: Our findings support the notion that cancer stem cells exist in the majority of renal tumors, although positive staining rates varied among different tumor types. In addition, CD133 and OCT3/4 expression in the majority of CCP-RCCs further support that this tumor is an independent entity of RCC derived from distal nephron tubules (taken together with its positive CK7 but negative P504S stains reported by others, and negative kidney injury molecule-1 staining found in our previous study).
Category: Genitourinary (including renal tumors)

Tuesday, March 20, 2012 9:30 AM

Poster Session III # 168, Tuesday Morning


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