Investigating intra-tumor heterogeneity and expression gradients of miR-21, miR-92a and miR-200c and their potential of predicting lymph node metastases in early colorectal cancer

TY - JOUR

T1 - Investigating intra-tumor heterogeneity and expression gradients of miR-21, miR-92a and miR-200c and their potential of predicting lymph node metastases in early colorectal cancer

AU - Jepsen, Rikke Karlin

AU - Novotny, Guy Wayne

AU - Klarskov, Louise Laurberg

AU - Christensen, Ib Jarle

AU - Høgdall, Estrid

AU - Riis, Lene Buhl

PY - 2016

Y1 - 2016

N2 - Introduction miR-21, miR-92a and miR-200c are regulators of pathways involved in migration, intravasation and metastasis, and their tumor expression levels have been proposed as potential prognostic markers in colorectal cancer (CRC). In two parallel cohorts we examine intra-tumor expression levels in early stage CRC tissue in order to determine intra-tumor heterogeneity, potential systematic intra-tumor expression gradients of the miRNAs and to investigate the association to metastatic disease in early stage CRC. Material and methods Two parallel studies on archived formalin-fixed paraffin-embedded (FFPE) CRC tissue. Intra-tumor and inter-patient variances were analyzed in 9 early metastatic CRCs by measuring expression levels by qRT-PCR on isolated tissue samples from luminal, central and invasive border zones. Associations between miRNA expression levels and early metastasizing tumors was investigated in FFPE tissue from invasive border and central tumor zones from 47 early metastatic CRCs matched with 47 non-metastatic CRCs. Intra-tumor expression gradients were analyzed on both cohorts. Results Mean intra-tumor coefficient of variation in the heterogeneity cohort was 38.5% (range: 33.1–49.0%) only slightly less than variation between patients (45.1%, range 37.0–49.5%). We demonstrated systematic expression gradients between tumor zones equal to a 3.23 (p = 0.003) and 1.36 (p = 0.014) fold lower expression in invasive areas for miR-200c, 1.52 (p < 0.001) and 1.27 (p = 0.021) fold lower expression in invasive areas for miR-92a. For miR-21 we found a 1.75 (p < 0.001) and 1.21 (p = 0.064) fold higher expression in invasive areas compared to luminal and central zones, respectively. No significant difference in expression levels between metastatic and non-metastatic tumors was demonstrated, nor a difference in intra-tumor gradients between metastatic and non-metastatic tumors. Conclusion This study provides evidence for moderate intra-tumor and inter-patient heterogeneities of three well-described potential prognostic markers in CRC. We demonstrate intra-tumor expression gradients indicating a differentiated expression of the target miRNAs between functional tumor zones, but the potential role as markers of early metastatic disease is still not fully clarified.

AB - Introduction miR-21, miR-92a and miR-200c are regulators of pathways involved in migration, intravasation and metastasis, and their tumor expression levels have been proposed as potential prognostic markers in colorectal cancer (CRC). In two parallel cohorts we examine intra-tumor expression levels in early stage CRC tissue in order to determine intra-tumor heterogeneity, potential systematic intra-tumor expression gradients of the miRNAs and to investigate the association to metastatic disease in early stage CRC. Material and methods Two parallel studies on archived formalin-fixed paraffin-embedded (FFPE) CRC tissue. Intra-tumor and inter-patient variances were analyzed in 9 early metastatic CRCs by measuring expression levels by qRT-PCR on isolated tissue samples from luminal, central and invasive border zones. Associations between miRNA expression levels and early metastasizing tumors was investigated in FFPE tissue from invasive border and central tumor zones from 47 early metastatic CRCs matched with 47 non-metastatic CRCs. Intra-tumor expression gradients were analyzed on both cohorts. Results Mean intra-tumor coefficient of variation in the heterogeneity cohort was 38.5% (range: 33.1–49.0%) only slightly less than variation between patients (45.1%, range 37.0–49.5%). We demonstrated systematic expression gradients between tumor zones equal to a 3.23 (p = 0.003) and 1.36 (p = 0.014) fold lower expression in invasive areas for miR-200c, 1.52 (p < 0.001) and 1.27 (p = 0.021) fold lower expression in invasive areas for miR-92a. For miR-21 we found a 1.75 (p < 0.001) and 1.21 (p = 0.064) fold higher expression in invasive areas compared to luminal and central zones, respectively. No significant difference in expression levels between metastatic and non-metastatic tumors was demonstrated, nor a difference in intra-tumor gradients between metastatic and non-metastatic tumors. Conclusion This study provides evidence for moderate intra-tumor and inter-patient heterogeneities of three well-described potential prognostic markers in CRC. We demonstrate intra-tumor expression gradients indicating a differentiated expression of the target miRNAs between functional tumor zones, but the potential role as markers of early metastatic disease is still not fully clarified.

KW - Early colorectal cancer

KW - Expression gradients

KW - Metastases

KW - microRNA-200c

KW - microRNA-21

KW - microRNA-92a

U2 - 10.1016/j.yexmp.2016.08.003

DO - 10.1016/j.yexmp.2016.08.003

M3 - Journal article

C2 - 27565378

AN - SCOPUS:84983805457

SN - 0014-4800

VL - 101

SP - 187

EP - 196

JO - Experimental and Molecular Pathology

JF - Experimental and Molecular Pathology

IS - 2

ER -