PLOD2 Is Essential to Functional Activation of Integrin β1 for Invasion/Metastasis in Head and Neck Squamous Cell Carcinomas

Abstract

Identifying the specific functional regulator of integrin family molecules in cancer cells is critical because they are directly involved in tumor invasion and metastasis. Here we report high expression of PLOD2 in oropharyngeal squamous cell carcinomas (SCCs) and its critical role as a stabilizer of integrin b1, enabling integrin b1 to initiate tumor invasion/metastasis. Integrin b1 stabilized by PLOD2-mediated hydroxylation was recruited to the plasma membrane, its functional site, and accelerated tumor cell motility, leading to tumor metastasis in vivo, whereas loss of PLOD2 expression abrogated it. In accordance with molecular analysis, examination of oropharyngeal SCC tissues from patients corroborated PLOD2 expression associated with integrin b1 at the invasive front of tumor nests. PLOD2 is thus implicated as the key regulator of integrin b1 that prominently regulates tumor invasion and metastasis, and it provides important clues engendering novel therapeutics for these intractable cancers.

PLOD2-driven IL-6/STAT3 signaling promotes the invasion and metastasis of oral squamous cell carcinoma via activation of integrin β1

“…2A and S2A and B ). We previously reported that PLOD2 increases cancer metastasis through stabilization of integrin β1 protein on the cancer cell surface via PLOD2-catalyzed lysyl hydroxylation ( 23 ). Therefore, the present study assessed whether the integrin β1 state is affected by PLOD2 itself and IL-6 treatment.…”

“…Cells were maintained in RPMI-1640 medium (FUJIFILM Wako Pure Chemical Corporation) containing 10% fetal bovine serum (FBS; HyClone; Cytiva) with 100 U/ml penicillin and 0.1 mg/ml streptomycin (Thermo Fisher Scientific, Inc.) at 37°C in 5% CO 2 . PLOD2 -knockout (PLOD2-KO) HSC-2 cell clones were generated with clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR associated protein 9 (Cas9)-based genome engineering technology as previously described ( 23 ), which were compared to the intact parental HSC-2 cells as the control [ PLOD2 -wild-type (PLOD2-WT)]. Briefly, the 23-base of gRNA (5′-CCAGGATAATGATGATGATCAGC-3′) containing the sequence of protospacer adjacent motif for PLOD2 targeting sequence (5′-GCTGATCATCATCATTATCC-3′) was determined from the CRISPRdirect website ( http://crispr.dbcls.jp/ ).…”

“…β-actin was used as a positive control and for the normalization of RT-PCR products. PCR primer sets were previously described by Ueki et al ( 23 ). The PCR products were detected using a ChemiDoc™ Touch Imaging System (Bio-Rad Laboratories, Inc.) and band intensity was analyzed using Image Lab software version 5.2 (Bio-Rad Laboratories, Inc.).…”

“…Several experimental contexts imitate the TME (including co-culture systems composed of hepatocellular carcinoma cells and cancer-associated fibroblasts; breast cancer cells and adipocytes) and induce aggressive invasion of each type of co-cultured cancer cells via upregulation of PLOD2 in the cancer cells ( 14 , 19 ). The results suggest that soluble factors produced in the co-cultures induce PLOD2 together with extracellular matrices so that integrin β1 on cancer cells becomes activated ( 23 ), eventually leading to increased invasiveness through an active interaction with the enriched collagen matrices in the extracellular space. The soluble factors that cause PLOD2 induction in cancer cells at significant levels are unknown.…”

The Role of Fibrosis in Osteoarthritis Progression

“…While the presence of fibrosis in OA patients was unknown, it is expected that PLOD2 may have higher expression in the subpopulation of OA patients with fibrosis. Ueki et al confirmed that the knockout of PLOD2 inhibited the tumorigenesis role of integrin β1 in tumor cells [ 102 ]. While it is still controversial, integrins are reported to be closely related to the pathogenesis of OA, and the confirmation of this process in OA might suggest a new candidate for OA treatment [ 103 , 104 ].…”