Alterations in enhancer of zeste homolog 2, matrix metalloproteinase-2 and tissue inhibitor of metalloproteinase-2 expression are associated with ex vivo and in vitro bone metastasis in renal cell carcinoma

Abstract

Abstract. Renal cell carcinoma (RCC) has a high potential for bone metastasis; however, the molecular mechanisms underlying this metastasis have remained to be elucidated. The present study aimed to explore the expression levels of enhancer of zeste homolog 2 (EZH2), matrix metalloproteinase-2 (MMP2) and tissue inhibitor of metalloproteinase-2 (TIMP2) as determinants of RCC-associated bone metastasis. Their expression was evaluated in a newly generated RCC cell subline that has a high potential for bone metastasis, in tissue specimens from metastasized bone tissues from patients with RCC and in RCC tissues without metastasis. A total of 25 RCC tissue specimens without metastasis and 13 RCC tissue specimens with bone metastasis were acquired for immunohistochemical analysis of EZH2, MMP2 and TIMP2 protein expression. The expression levels of EZH2, MMP2 and TIMP2 mRNA and protein were analyzed in the ACHN and ACHN-BO5 cell lines using western blot and reverse transcription polymerase chain reaction (PCR) analyses. Methylation-specific PCR was also used to analyze TIMP2 promoter methylation. EZH2 and MMP2 proteins were found to be expressed at higher levels in tissues from patients where RCC had metastasized to the bone as compared with those in RCC patients without metastasis, whereas there was no significant difference in the expression of TIMP2 protein between the two tissues. Furthermore, the expression of EZH2 protein was correlated with MMP2 expression, but there was no significant correlation between the expression of EZH2 and TIMP2 proteins. The in vitro results using cell lines confirmed the ex vivo findings, indicating that the expression levels of EZH2 and MMP2 protein and mRNA were higher in ACHN-BO5 cells than those in ACHN cells. By contrast, TIMP2 protein and mRNA expression levels were lower in ACHN-BO5 cells than those in the parental ACHN cells. The TIMP2 promoter was highly methylated in ACHN-BO5 cells compared with that in ACHN cells. Upregulation of EZH2, MMP2 and TIMP2 expression was correlated with metastasis of RCC to bone tissues ex vivo and in vitro. Further studies are required in order to elucidate the mechanism underlying the altered expression of these genes. IntroductionRenal cell carcinoma (RCC), which has been suggested to originate from the renal tubules and collecting tube epithelial cells, accounts for 85% of malignant kidney neoplasms and ~2% of all human malignancies (1,2). RCC is a pathologically heterogeneous disease, which can be classified into clear, papillary, granular, spindle and mixed cell subtypes based on certain cytoplasmic features (3). RCC morbidity increases by 2% annually and mortality has reached ~100,000 cases/year worldwide (4). Approximately 30% of patients with RCC develop metastatic disease, most frequently in the lungs, bones or brain (5). A clinical study confirmed that osteolysis represented 30% of the total metastatic disease cases associated with RCC (6). The incidence rate of bone tissue metastasis was higher in autopsy data from patients with RCC (5...

Thrombospondin-2 promotes prostate cancer bone metastasis by the up-regulation of matrix metalloproteinase-2 through down-regulating miR-376c expression

“…Previous studies have indicated the critical roles of MMP-2 in bone metastasis in various tumors. MMP-2 expression is contributed to matrix degradation and osteolytic bone metastasis in many tumors such as prostate cancer [34], breast cancer [35, 36], and renal cell carcinoma [37]. To explore the role of TSP-2/MMP-2 axis in bone metastasis of prostate cancer, we performed mouse models of bone metastasis by intratibial injection of cancer cells, and the bone metastasis was then detected by bioluminescence imaging.…”

Bone Metastasis from Renal Cell Carcinoma

“…Wang et al [ 80 ] explored the expression levels of enhancer of zeste homolog 2 (EZH2), matrix metalloproteinase-2 (MMP2) and tissue inhibitor of metalloproteinase-2 (TIMP2) as determinants of RCC-associated bone metastasis. The EZH2 and MMP2 proteins were more expressed in tissues of patients with RCC bone metastasis.…”

“…The TIMP2 promoter was also highly methylated in ACHN-BO5 cells, an ACHN cell subline with high potential of bone metastasis, compared to in ACHN cells. The upregulation of EZH2, MMP2 and TIMP2 expressions correlated with RCC metastasis to bone tissues ex vivo and in vitro [ 80 ].…”

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“…5B). These results suggested that PRR11 contributed to OC cell proliferation, partly by affecting the [11]. Activated MMP2 degrades extracellular matrix (ECM) components to allow cancer cell expansion without resistance, whereas TIMP-2 is a specific inhibitor of MMP2 [12].…”