Cancer Management and Research Dovepress open access to scientific and medical research Open Access Full Text Article ORIGINAL RESEARCH Aberrant Expression Of PDCD4/eIF4A1 Signal Predicts Postoperative Recurrence For Early- Stage Oral Squamous Cell Carcinoma This article was published in the following Dove Press journal: Cancer Management and Research Mengxiang Zhao1,* Background: Programmed cell death 4 (PDCD4) as a tumor suppressor gene inhibits Liang Ding 1,* growth and metastasis of cancer cells, which involved with eIF4A1, the inhibitor of transla- Yan Yang 2 tion initiation. Although the prognosis of early-stage oral squamous cell carcinoma (OSCC) Sheng Chen2 is generally better, but many patients occur recurrence after surgery. Understanding the Nisha Zhu1 clinical expression pattern of PDCD4/eIF4A1 signal would provide diagnostic biomarker and target therapy premise for early-stage OSCC patients. Yo n g F u 1 Methods: Immunohistochemical analysis was performed on 69 early-stage (T1/2N0M0) Yanhong Ni1 2 OSCC samples to evaluate temporal expression and prognostic value of eIF4A1 and PDCD4 Zhiyong Wang in early-stage OSCC according to cell types and microlocalization. The correlations between 1Central Laboratory of Stomatology, PDCD4/eIF4A1 signal and Ki-67, postoperative recurrence and metastasis were determined. Nanjing Stomatological Hospital, Medical Results: We found that PDCD4 was presented in tumor cells (TCs) and tumor-infiltrating School of Nanjing University, Nanjing 210093, People’s Republic of China; lymphocytes (TILs) but absent in fibroblast-like cells (FLCs). eIF4A1 was only presented in 2Department of Oral and Maxillofacial TCs. PDCD4TCs was negative associated with eIF4A1TCs in tumor center, and patients with Surgery, Nanjing Stomatological Hospital, low PDCD4TCs or high eIF4A1TCs had poorer differentiation. Moreover, aberrant PDCD4/ Medical School of Nanjing University, Nanjing 210008, People’s Republic of eIF4A1 signal led to higher Ki-67 level. Interestingly, patients with low expressed China PDCD4TILs had better prognosis, indicating the function heterogeneity of PDCD4 in different TCs TCs *These authors contributed equally to cell types. Furthermore, low PDCD4 and high eIF4A1 predicted higher postoperative this work recurrence rate and are significant independent risk factors for early-stage OSCC. Conclusion: Patients with low PDCD4TCs and high eIF4A1TCs have higher recurrence rate and poor clinical outcome. Of note, PDCD4TILs exerts contradictory function. Thus, PDCD4/ eIF4A1 targeting therapeutics should consider the function heterogeneity of PDCD4. Keywords: PDCD4, eIF4A1, early-stage OSCC, prognosis, diagnosis Correspondence: Zhiyong Wang Introduction Department of Oral and Maxillofacial Surgery, Nanjing Stomatological Hospital, Oral squamous cell carcinoma (OSCC) is malignant oral tumor which accounts for Medical School of Nanjing University, 30 24% of head and neck cancers. Postoperative local recurrence is a main reason Zhongyang Road, Nanjing 210008, Jiangsu, 1,2 People’s Republic of China affecting 5-year survival rate of OSCC in early stage, therefore, discovery of Tel +86 137 709 2448 Email [email protected] effective biomarkers and their effects on therapeutic responses are awaited to improve the early-stage OSCC patient prognosis. Yanhong Ni Central Laboratory of Stomatology, PDCD4 is a tumor suppressor gene that located at human chromosome 10q24. Nanjing Stomatological Hospital, Medical Compared with normal tissues, PDCD4 has a lower expression in many cancers, School of Nanjing University, 22 Hankou Road, Nanjing, Jiangsu 210093, People’s such as colorectal cancer, esophageal squamous cell carcinoma and medullary Republic of China thyroid carcinoma.3–5 The deficiency of PDCD4 in colorectal cancer cells ulti- Tel +86 138 1451 6225 3 Email [email protected] mately promoted cell survival, proliferation and metastasis. On the other hand, submit your manuscript | www.dovepress.com Cancer Management and Research 2019:11 9553–9562 9553 DovePress © 2019 Zhao et al. This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at https://www.dovepress.com/terms.php – http://doi.org/10.2147/CMAR.S223273 and incorporate the Creative Commons Attribution Non Commercial (unported, v3.0) License (http://creativecommons.org/licenses/by-nc/3.0/). By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. For permission for commercial use of this work, please see paragraphs 4.2 and 5 of our Terms (https://www.dovepress.com/terms.php). Zhao et al Dovepress overexpression of PDCD4 in human prostate cancer cells Stomatology Hospital, Nanjing University. Written informed induced a significant reduction in cell growth.6 The present consent was obtained from all the patients. All these retro- research of PDCD4 are mainly conducted on cancer cells, spective specimens were handled and anonymized according but tumor is a heterogeneous cell population, it is neces- to ethical and legal standards. There were 21 patients died sary to study the expression pattern of PDCD4, including from OSCC (n=69) in our study until January 2019. None of location and cell types. the patients had received chemotherapy or radiotherapy prior The DEAD-box helicase eIF4A1 is needed to unwind to surgery and all 69 patients were followed-up until January structured RNA elements within the 5′ untranslated region 2019. (5′UTR) to enable ribosome binding and scanning. A number of known oncogenes such as CBC25B, SMAD2, Immunohistochemistry c-myc, c-myb and TGFβ1 were confirmed as requiring IHC was employed on 3 μmformalin-fixed paraffin-embedded eIF4A1 for their efficient translation.7 PDCD4 binds with sections using anti-PDCD4 (1:200; ab80590; Abcam, eIF4A1 to inhibit its enzymatic activity, thereby leaving Cambridge, MA, USA), anti-Ki-67 (1:100; ab16667; the mRNA methylated decapping process unfinished and Abcam) and anti-eIF4A1 (1:200; ab31217; Abcam). All sec- inhibiting the proliferation of tumor cells. PDCD4/eIF4A1 tions were subsequently incubated with secondary antibody signal influences breast cancer cell proliferation and cell (Vector Laboratories, Burlingame, CA, USA) and developed cycle, decreased eIF4A1 activity slowed down cellular in diaminobenzidine (DAB). All sections were then washed in proliferation significantly.8 Degraded PDCD4 greatly PBS. Appropriate positive and negative controls were included enhanced eIF4A activity, then eIF4A-mediated enhance- for each relevant stain. ment of oncogene translation may be a critical component for lymphoma progression.9 However, the clinical signifi- Quantification Of Immunohistochemistry cance of PDCD4/eIF4A1 signal axis is still unclear in To evaluate the immune expression of PDCD4, eIF4A1 OSCC, which limits its efficacy of targeting therapy. and Ki-67 in tumor cells, tumor-infiltrating lymphocytes In the present study, we focused on the expression (TILs) and stroma fibroblast-like cells (FLCs), slides were pattern of PDCD4/eIF4A1 signal in OSCC, we analysed visualized by two senior pathologists who evaluated each the temporal distribution of PDCD4/eIF4A1 signal in expression quantitatively. The patterns of PDCD4 and early-stage OSCC by IHC according to distinct cell com- eIF4A1 expression locations in OSCC specimens were fi ponents in tumor micro-environment, including tumor de ned and divided into two regions: tumor center and cells and tumor-infiltrating lymphocytes (TILs). Further, invasive front. Ki-67 staining was only scored in the tumor we determined correlations between the expression of cells. We distinguished stroma FLCs from tumor cells fi PDCD4/eIF4A1 signal and clinic pathological parameters according to the typical broblast shape, long spindle- and postoperative local recurrence in this study. Our find- shaped cells with small cytoplasmic protrusions located ings reveal this signal may promote OSCC progression in the tumor stroma. with diagnostic and prognostic value, of which early- IHC staining was scored according to the percentage of 10 stage OSCC patients may have a worse prognosis. positive cells and staining intensity. Staining intensity was graded as negative (=0), weak (=1), moderate (=2) or strong (=3), and reactivity was assessed by the percentage of posi- Materials And Methods tively staining cells (0–5% [=0], 5–25% [=1], 26–50% [=2], Patients And Samples 51–75%[=3]or76–100% [=4]). The IHC score was calcu- The experimental study group randomly included 69 patients lated by multiplying the grade of the staining intensity by that diagnosed from 2007 to 2014 with early-stage OSCC of the staining percentage, giving a minimum score of 0 and a (T1N0M0-T2N0M0). The 5-year survival rate was 69.6% maximum of 12. High and low expressions of PDCD4 and in the 69 samples. All the 69 cases of OSCC included 8 cases eIF4A1 were defined by the median of IHC scores. of gingival cancer, 8 cases of buccal cancer, 9 cases of palate cancer and 44 cases of tongue cancer. The patients with Statistical Analysis primary tumors were diagnosed by haematoxylin and eosin The SPSS version 16.0 (SPSS Inc., Chicago, IL, USA) and (H&E) staining by experienced pathologists, and this study Prism statistical software packages (version 8.0, GraphPad was approved by the Research Ethics Committee of Nanjing Software Inc., San Diego, CA, USA) were used for 9554 submit your manuscript | www.dovepress.com Cancer Management