Peripheral blood mononuclear CD133 mRNA levels correlates with response to treatment in patients with gastrointestinal stromal tumors

Epigenetic Regulation of CD133 in Gastrointestinal Stromal Tumors

OBJECTIVES

This study ascertained the regulation of the stem cell marker CD133 and its potential applicability for prognostication of gastrointestinal stromal tumors (GISTs).

METHODS

A total of 95 resected GISTs were included in the study. CD133 protein expression was assessed immunohistochemically on tissue microarrays. Methylation percentage was quantified by pyrosequencing. Gene expression in cell lines GIST48b and GIST882 upon treatment with DNA demethylation agent 5-aza-2'-deoxycytidine was analyzed by quantitative polymerase chain reaction.

RESULTS

The expression of hypermethylated CD133 could be reactivated in the GIST cell line upon hypomethylation with the drug. Similarly, in patient material, CD133 methylation percentage correlated inversely with the protein expression and reflected tumor size with hypermethylation in small (<2 cm) tumors and virtually no methylation in large (>10 cm) GISTs. The gene's methylation percentage and expression level were clearly specific to anatomic sites and distinct driver mutations. KIT -mutant gastric GISTs exhibited significantly lower methylation degrees and concomitant high CD133 protein abundance compared with KIT -mutant GISTs from the small intestine. CD133 hypermethylation was documented in PDGFRA -mutant gastric GISTs along with low CD133 expression compared with KIT -mutant gastric GISTs. High CD133 expression was a prognosticator of shorter disease-free survival in all patients. In a subgroup of KIT -mutant gastric GISTs, low CD133 methylation degree was correlated with a shorter disease-free survival.

CONCLUSIONS

Our results strongly suggest epigenetic regulation of CD133 expression by promoter methylation in GISTs. Pending further validation studies, high abundance of the protein can serve as a marker for malignant GISTs.

Quantification of peripheral blood CD133 mRNA in identifying metastasis and in predicting recurrence of patients with clear cell renal cell carcinoma

OBJECTIVES

To investigate whether CD133 messenger ribonucleic acid (mRNA) could provide useful information to identify metastasis or predict recurrence in patients with clear cell renal cell carcinoma (cRCC).

METHODS AND MATERIALS

This study included 86 patients with cRCC and 30 healthy controls. Real-time reverse transcriptase-polymerase chain reaction was used to quantify CD133 mRNA in peripheral blood mononuclear cells before nephrectomy.

RESULTS

The average CD133 mRNA in patients with metastatic cRCC (1.546 ± 0.291) was significantly higher than that in those with localized cRCC (1.034 ± 0.316, P = 0.022) or in controls (0.042 ± 0.028, P = 0.001). Metastasis could be identified with a sensitivity of 82.6% at specificity of 69.8% by CD133 mRNA. Among patients with localized cRCC, there was a significant difference in CD133 mRNA between the patients with recurrence (1.136 ± 0.127) and without recurrence (1.010 ± 0.091, P = 0.047). Recurrence could be identified with a sensitivity of 75.0% at specificity of 61.8%. Patients with a higher CD133 mRNA had a significantly higher recurrence rate than those with a low CD133 mRNA (P = 0.019).

CONCLUSIONS

CD133 mRNA can be useful for identifying metastasis, predicting recurrence, and stratifying the patients into different risk groups for possible adjuvant treatment.