Xiaojing Xing

Biglycan is an important component of the extracellular matrix, and it is also a member of small leucine-rich proteoglycan family. Previous studies indicated that the expression of biglycan was increased in a variety of tumor tissues, including colon cancer. However, the mechanisms underlying its effects in colon cancer remain to be fully elucidated. In the present study, the effects of biglycan knockdown on colon cancer cell proliferation, migration, invasion and apoptosis were investigated. The mRNA expression levels of biglycan in the HCT116 colon cancer cell line were downregulated using RNA interference, and the stably transfected cell line was obtained through G418 screening for subsequent experiments. The results revealed that downregulation of the expression of biglycan suppressed cell proliferation and caused a cell cycle arrest at the G0/G1 phase. The results of the western blot analysis also revealed that the expression levels of cell cycle‑associated proteins, including cyclin A and cyclin D1, were markedly decreased following silencing of biglycan, whereas the expression levels of p21 and p27 were markedly increased compared with that of the short hairpin RNA control group. Furthermore, the decreased expression of biglycan inhibited colon cancer cell migration and invasion, and induced apoptosis. A complete inhibition of the p38 signaling pathway with SB203580 effectively reversed the increase in apoptotic cell numbers induced by biglycan downregulation. Taken together, the results of the present study indicated that biglycan exerts an important role in cell proliferation, migration, invasion and apoptosis in colon cancer, and that biglycan regulates the p38 MAPK signaling pathway by exerting an antiapoptotic effect. Therefore, biglycan may represent a putative target for colon cancer gene therapy.

Biglycan is an important component of the extracellular matrix, which belongs to the small leucine-rich proteoglycan family. Recent studies have shown that biglycan expression is elevated in many tumor tissues and implies poor prognosis, such as colon cancer. However, the molecular mechanism of biglycan in colon cancer has not been investigated. The present study aimed to investigate the effects of biglycan on vascular endothelial growth factor (VEGF) expression in colon cancer cells and on tumor angiogenesis in vivo. Biglycan overexpression vectors were constructed, and the stable biglycan overexpression in human colon cancer cell lines (HCT116 cells) was established by G418 screening. The stable cell clones were subsequently used to initiate tumor xenografts in nude mice. Our results showed that biglycan overexpression notably up-regulated the levels of VEGF in colon cancer cells, which was further confirmed by immunohistochemistry analysis in the xenograft colon tumors. Moreover, high levels of biglycan promoted angiogenesis and colon tumor growth, as evidenced by the increased cell viability, colon tumor size, and weight, as well as the CD34 expression. Additionally, we found that the extracellular signal-regulated kinase (ERK) signaling pathway was activated by biglycan in colon cancer cells. The ERK inhibitor PD98059 dramatically reversed the increased expression of VEGF induced by biglycan. Taken together, our results indicated that biglycan up-regulated VEGF expression in colon cancer cells and promoted tumor angiogenesis. Biglycan-mediated VEGF regulation may correlate with the activation of the ERK signaling pathway. Therefore, biglycan may be a promising target for anti-angiogenic therapy for cancer.

Biglycan, an extracellular matrix protein, has been implicated in the oncogenesis and cancer development in various types of human cancer. The clinical significance of biglycan in colorectal cancer, however, remains unclear. In the present study, biglycan mRNA expression was analyzed in 110 samples (primary colorectal tumor and matched adjacent normal tissue) derived from 55 patients with colorectal cancer using quantitative real-time RT-PCR. The correlations between biglycan up-regulation and the clinicopathological data were also evaluated. We found that the up-regulation of biglycan occurred in 61.8% (34/55) of colorectal cancer tissues, and biglycan expression in colorectal cancer tissues was markedly higher than that in corresponding normal tissues (P = 0.0264). Moreover, statistical analysis displayed a significant correlation in biglycan up-regulation with poor tumor differentiation (P = 0.009), lymph node metastasis (P = 0.041), and distant metastasis (P = 0.036). However, there was no significant correlation between biglycan up-regulation and other clinicopathological factors (all P > 0.05). In conclusion, biglycan may be a potential marker for the malignancy of colorectal cancer.