Collapsin response mediator protein 4 promotor methylation level as a potential predictor for diagnosing primary malignant lymphoma of the prostate

Abstract

Background: Primary malignant lymphoma of the prostate (PMLP) is prone to occur in the elderly, and it has no significant correlation with lactate dehydrogenase (LDH) and prostate specific antigen (PSA). Clinical symptoms and imaging data of PMLP remain unspecific, and its prognosis is poor. A previous result showed that collapsin response mediator protein 4 (CRMP4) promotor methylation can be used as a predictor for lymph node metastases in prostate biopsies. However, the relationship between CRMP4 promotor methylation and PMLP has not been studied.

Methods: We investigated the clinicopathological features of PMLP and the significance of CRMP4 methylation in PMLP. The clinical data and diagnosis information of 10 patients with PMLP were retrospectively analyzed. The CRMP4 promotor methylation level in paraffin-embedded tissues of the 10 patients with PMLP were determined and then compared to limited prostate cancer (LPCa) and its negative lymph node tissue [LPCa-LN (-) (10 cases)] and also to metastatic prostate adenocarcinoma (mPCa) and its positive lymph node tissue [mPCa-LN (+) (10 cases)]. Methylation of the CRMP4 promotor in each group was analyzed statistically. A receiver operating characteristic (ROC) curve was used to analyze the diagnostic value of CRMP4 methylation in PMLP.

Results: The average methylation value of CRMP4 in 10 PMLP patients, 20 cases of prostate adenocarcinoma tissue, 10 cases LPCa-LN (-) and 10 cases mPCa-LN (+) were 42.3, 30.6, 6.7 and 20.3%, respectively. A Kruskal-Wallis test showed that the difference of CRMP4 methylation was significant (X² = 38.0, P < 0.001). An ROC curve analysis found that CRMP4 methylation > 40.9% could diagnose PMLP. This method had 90% sensitivity and 95% specificity under conditions of CRMP4 methylation > 40.9%. The area under the curve (AUC) was 0.957.

Conclusions: Methylation of the CRMP4 gene was significantly increased in PMLP, and it is expected to become a new predictor for PMLP.

Keywords: Collapsin response mediator protein 4 (CRMP4); Methylation; Predictor; Primary malignant lymphoma prostate (PMLP); ROC curve.

Fig. 1

Preoperative diagnosis was performed by pelvic CT or MRI examination. The results suggested that the prostate was significantly augmented, the internal density of the prostate was uneven and spot-like calcified. Pelvic CT figure: a plane scan, b curve arterial phase, c curve vein; MRI figure: d T1W1, e T2W1, f DWI

Fig. 2

IHC results of DLBCL. a Hematoxylin and eosin (H&E) stain, ×200. b CD20 (positive), IHC, ×200, c CD10 (negative), IHC, ×200. d CD3 (background small lymphocytes positive, tumor cell negative). IHC, ×200. e MUM1 (positive), IHC, ×200; f Ki-67 (70% +), IHC, ×200

Fig. 3

IHC results of MCL. a H&E stain, ×200. b CD20 (positive), IHC, ×200. c CD5 (negative), IHC, ×200. d CD10 (negative), IHC, ×200. e Cyclin D1 (positive), IHC, ×200; f Ki-67 (30% +), IHC, ×200

Fig. 4

Quantitative pyrosequencing of methylation sites within CRMP4 promoter region. The CRMP4 gene promoter region A S1 (methylation sites − 848 and − 841) and region B S2 (methylation sites − 680, − 678, − 674, − 671, − 665, − 660, and − 658) was significantly methylated, and the methylation of site S3–S6 was not significant

Fig. 5

The CRMP4 methylation site was detected in each group. A1/A2 methylation values of the unmethylated control group. B1/B2 was histometric methylation values of 10 cases of PMLP tissue. C1/C2 was histometric methylation values of 20 patients with prostate adenocarcinoma (10 patients with LPCa and 10 patients with mPCa). D1/D2 was histometric methylation value of 10 cases of LPCa-LN (−). E1/E2 was histometric methylation value of 10 cases of mPCa-LN (+). F1/F2 was the methylation value of the control group. The red dotted frame represents S1 and S2 and is listed in the analyzed methylation site of CRMP4

Fig. 6

The box pattern shows the difference in CRMP4 methylation values for each group. The average methylation of CRMP4 promoter at nine sites (methylation sites − 680, − 678, − 674, − 671, − 665, − 660, − 658, − 848, and − 841) in PMLP, prostate adenocarcinoma (including LPCa and mPCa), LPCa-LN (−) and mPCa-LN (+) were 42.3, 30.6, 6.7, 20.3%, respectively. The difference was clear. PMLP Primary malignant lymphoma of the prostate, LPCa localized prostate cancer, LPCa-LN (−) negative lymph nodes of the localized prostate cancer, mPCa metastatic prostate cancer, and mPCa-LN (+) positive lymph nodes of the metastatic prostate cancer

Fig. 7

ROC curve analysis of predictive value of CRMP4 methylation in PMLP diagnosis. ROC curve analysis showed that the sensitivity of predicting PMLP was 90% when CRMP4 methylation > 40.9%. The predictive specificity was 95% and the area under curve (AUC) was 0.957