Calreticulin Regulates β1-Integrin mRNA Stability in PC-3 Prostate Cancer Cells.

Yueh-Chien Lin,Yi-Cheng Weng,Yuan-Li Huang,Chih-Yu Chen,Ming-Hua Wang,Wei-Min Chen,Pei-Yi Wu

doi:10.3390/biomedicines10030646

Abstract

Prostate cancer (PCa) is the major cause of cancer-related death among aging men worldwide. Recent studies have suggested that calreticulin (CRT), a multifunctional chaperon protein, may play an important role in the regulation of PCa tumorigenesis and progression. However, the underlying mechanisms are still unclear. Integrin is an important regulator of cancer metastasis. Our previous study demonstrated that in J82 bladder cancer cells, CRT affects integrin activity through FUBP-1-FUT-1-dependent fucosylation, rather than directly affecting the expression of β1-integrin itself. However, whether this regulatory mechanism is conserved among different cell types remains to be determined. Herein, we attempted to determine the effects of CRT on β1-integrin in human prostate cancer PC-3 cells. CRT expression was suppressed in PC-3 cells through siRNA treatment, and then the expression levels of FUT-1 and β1-integrin were monitored through RT-PCR. We found that knockdown of CRT expression in PC-3 cells significantly affected the expression of β1-integrin itself. In addition, the lower expression level of β1-integrin was due to affecting the mRNA stability. In contrast, FUT-1 expression level was not affected by knockdown of CRT. These results strongly suggested that CRT regulates cellular behavior differently in different cell types. We further confirmed that CRT directly binds to the 3′UTR of β1-integrin mRNA by EMSA and therefore affects its stability. The suppression of CRT expression also affects PC-3 cell adhesion to type I collagen substrate. In addition, the levels of total and activated β1-integrin expressed on cell surface were both significantly suppressed by CRT knockdown. Furthermore, the intracellular distribution of β1-integrin was also affected by lowering the expression of CRT. This change in distribution is not lysosomal nor proteosomal pathway-dependent. The treatment of fucosydase significantly affected the activation of surface β1-integrin, which is conserved among different cell types. These results suggested that CRT affects the expression of β1-integrin through distinct regulatory mechanisms.

Highlights

Prostate cancer (PCa) is one of the most common cancers and is the major cause of cancer-related death among aging men worldwide
Our previous study in bladder cancer has demonstrated that CRT affects β1-integrin activity through FUBP-1-FUT-1-dependent fucosylation, rather than directly affecting the expression of β1-integrin itself [10]
The mRNA expression level of β1-integrin was downregulated in CRT-knockdown (CRT-KD) PC-3 cells (Figure 1B)

Summary

Introduction

Prostate cancer (PCa) is one of the most common cancers and is the major cause of cancer-related death among aging men worldwide. 38 men dies from the disease [1,2]. PCa tumors usually originate from the glandular tissue. Biomedicines 2022, 10, 646 of the prostate with uncontrolled proliferation. Androgen has been known to play a vital role in the progression of PCa [3–6]. Hormone therapy, androgen deprivation or androgen ablation, has remained a standard therapy for patients with metastatic PCa for the past several decades [4]. Hormone therapy is not curative, and the cancer frequently relapses to a more malignant form. In order to elucidate the mechanism by which

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Conclusion