Low expression of olfactomedin 4 correlates with poor prognosis in smoking patients with non–small cell lung cancer

Olfm4 Is Highly Expressed in HCC Patients and as a Biomarker and Therapeutic Target for HCC

Hepatocellular carcinoma (HCC) is one of the primary types of cancer that claims many lives worldwide, and its incidence continues to increase. Conventional therapies against liver cancer are inadequate, and the pathogenesis of HCC remains unclear. Thus, not only are more effective therapies to treat HCC required but also identification of the key genes involved in its pathogenesis is important for developing such therapies. This study found that olfactomedin 4 (OLFM4) level is higher in HCC patients than in healthy individuals. Furthermore, HCC patients also have higher messenger ribonucleic acid (mRNA) expression level in HCC tissues than in liver paracancerous tissues. OLFM4 has high predictive capacity as a biomarker for HCC and closely correlates to tumor size. It is confirmed that OLFM4 contributes to cancer cell proliferation, and HIF1α is involved in this process. Thus, the OLFM4/HIF-1α axis might be a target signaling pathway for developing novel drugs to treat HCC.

Transcriptomic analysis reveals a WNT signaling pathway-based gene signature prognostic for non-small cell carcinoma

The value of combining multiple candidate genes into a panel to improve biomarker performance is increasingly emphasized. Genes associated with WNT signaling are widely-reported to provide prognostic signatures in non-small cell carcinoma (NSCLC). Screening of genes involved in this signaling pathway facilitated selection of an optimal candidate biomarker gene combination and development of an NSCLC prognostic model based on expression of these genes. Risk scores derived from the model performed well in predicting survival; in the training dataset, samples achieving a high risk score exhibit a shorter survival interval (median survival time 34.8 months, 95% CI 31.1-41.0) than did samples achieving a low risk score (median survival time 72.0 months, 95% CI 59.3-87.5, p=2e-11), and exhibited higher oncogene and lower tumor suppressor gene expression. Receiver-operator characteristic curves based on three-year survival demonstrate that the model outperformed clinical prognostic indicators. In addition, the model was validated in four independent cohorts, demonstrating robust NSCLC prognostic value. Correlation analyses reveal that the model offers efficacy independent of other clinical indicators. Gene Set Enrichment Analysis (GSEA) reveals that the model reflects variable tissue functional states relevant to NSCLC biology. In summary, the signature model shows potential as a valuable and robust NSCLC prognostic indicator.

Clinicopathological significance of olfactomedin-4 in extrahepatic bile duct carcinoma

The clinicopathological and prognostic significance of olfactomedin-4 (OLFM4) expression has not yet been elucidated in extrahepatic bile duct carcinomas (EBDCs). Immunohistochemical analysis of OLFM4 expression in 31 normal biliary epithelia, 33 biliary intraepithelial neoplasias (BilINs), and 180 surgically resected EBDCs (54 perihilar and 126 distal) was performed and was used to analyze clinicopathological variables including patient survival. The expression of OLFM4 showed a progressive increase from normal biliary epithelia (0.2 ± 0.4) to BilINs (2.8 ± 3.2) to EBDCs (4.6 ± 4.2; P < 0.001). OLFM4 was highly expressed in 26.1% (47/180) of the EBDC cases, and high OLFM4 levels were more frequently observed in tumors with nodular growth (P = 0.029), well differentiation (P = 0.011), and lower T-category (P = 0.025) and stage grouping (P = 0.013). Patients with EBDC having high expression of OLFM4 had better survival than those with low expression of OLFM4 (median, 43.3 vs. 29.2 months; P = 0.037). OLFM4 might play an important role in carcinogenesis and in the progression from BilINs to EBDCs. High OLFM4 expression predicted less aggressive clinical behavior in patients with EBDC.

High expression of olfactomedin-4 is correlated with chemoresistance and poor prognosis in pancreatic cancer

Pancreatic cancer has an extremely poor prognosis, and identification of novel predictors of therapeutic efficacy and prognosis is urgently needed. Chemoresistance-related molecules are correlated with poor prognosis and may be effective targets for cancer treatment. Here, we aimed to identify novel molecules correlated with chemoresistance and poor prognosis in pancreatic cancer. We established 10 patient-derived xenograft (PDX) lines from patients with pancreatic cancer and performed next-generation sequencing (NGS) of tumor tissues from PDXs after treatment with standard drugs. We established a gene-transferred tumor cell line to express chemoresistance-related molecules and analyzed the chemoresistance of the established cell line against standard drugs. Finally, we performed immunohistochemical (IHC) analysis of chemoresistance-related molecules using 80 pancreatic cancer tissues. From NGS analysis, we identified olfactomedin-4 (OLFM4) as having high expression in the PDX group treated with anticancer drugs. In IHC analysis, OLFM4 expression was also high in PDXs administered anticancer drugs compared with that in untreated PDXs. Chemoresistance was observed by in vitro analysis of tumor cell lines with forced expression of OLFM4. In an assessment of tissue specimens from 80 patients with pancreatic cancer, Kaplan-Meier analysis showed that patients in the low OLFM4 expression group had a better survival rate than patients in the high OLFM4 expression group. Additionally, multivariate analysis showed that high expression of OLFM4 was an independent prognostic factor predicting poor outcomes. Overall, our study revealed that high expression of OLFM4 was involved in chemoresistance and was an independent prognostic factor in pancreatic cancer. OLFM4 may be a candidate therapeutic target in pancreatic cancer.

Blocking OLFM4/HIF-1α axis alleviates hypoxia-induced invasion, epithelial-mesenchymal transition, and chemotherapy resistance in non-small-cell lung cancer

Hypoxia is a common biological hallmark of solid cancers, which has been proposed to be associated with oncogenesis and chemotherapy resistance. The purpose of the present study was to investigate the role and underlying mechanisms of olfactomedin 4 (OLFM4) in the hypoxia-induced invasion, epithelial-mesenchymal transition (EMT), and chemotherapy resistance of non-small-cell lung cancer (NSCLC). We observed dramatically upregulated expression of OLFM4 in several NSCLC cell lines, and this effect was more pronounced in A549 and H1299 cells. In addition, our data revealed that OLFM4 expression was remarkably increased in both A549 and H1299 cells under hypoxic microenvironment, accompanied by enhanced levels of hypoxia-inducible factor (HIF)-1α protein. The HIF-1α level was elevated in response to hypoxia, resulting in the regulation of OLFM4. Interestingly, OLFM4 was a positive regulator of hypoxia-driven HIF-1α production. Moreover, depletion of OLFM4 modulated multiple EMT-associated proteins, as evidenced by the enhanced E-cadherin levels along with the diminished expression of N-cadherin and vimentin in response to hypoxia, and thus blocked invasion ability of A549 and H1299 cells following exposure to hypoxia. Furthermore, ablation of OLFM4 accelerated the sensitivity of A549 cells to cisplatin under hypoxic conditions, implying that OLFM4 serves as a key regulator in chemotherapeutic resistance under hypoxia. In conclusion, OLFM4/HIF-1α axis might be a potential therapeutic strategy for NSCLC.

Altered DNA methylation is associated with aberrant stemness gene expression in early‑stage HNSCC

Head and neck squamous cell carcinoma (HNSCC) is characterized by morphological and functional cellular heterogeneity, which are properties of progenitor cells, as opposed to cell alterations caused by accidental expression of stem cell‑related molecules. The expression levels of stemness molecules and their distribution in HNSCC are unclear. As regards sporadic cellular heterogeneity, methylation is an important factor for transcriptional regulation in tumors. Integrative screening analysis of mRNA expression and altered methylation status was performed with original microarrays in 12 tumor and non‑tumor pairs of oral squamous cell carcinoma (SCC) cases. From this data set, genes regulated via aberrant DNA methylation and classified proteins were validated by function clustering. Olfactomedin 4 (OLFM4), known as an intestinal stemness molecule and cell‑cell adhesion factor, was found to be highly expressed in tumors, with an mRNA expression ratio [tumor/normal (T/N)] of 40.7686 and low methylation (‑18.02%) in the promoter region. In addition, the OLFM4 expression levels increased following treatment with the demethylating agent 5‑azacytidine in two HNSCC cell lines. Furthermore, the expression levels of OLFM4 in 59 cases of early‑stage tongue SCC were analyzed using immunohistochemistry to examine protein expression corresponding to the histopathological definition of tumors and to evaluate prognosis. The aberrant stemness gene expression caused by altered DNA methylation appeared to regulate early‑stage HNSCC characteristics. The results of the present study indicated a correlation between OLFM4 expression and promoter methylation, and suggest that it plays an important role in tumor cell heterogeneity in HNSCC.

OLFM4 Expression in Ductal Carcinoma In Situ and in Invasive Breast Cancer Cohorts by a SWATH-Based Proteomic Approach

Human olfactomedin-4 (OLFM4) is a secreted protein involved in a variety of cellular functions including proliferation, differentiation, apoptosis, and cell adhesion. OLFM4 expression has been studied in several tumor types including gastric, colorectal, lung, and endometrioid cancers where it has been suggested to be an independent favorable or unfavorable prognostic marker. For breast cancer, the clinical significance of OLFM4 is still unclear. In the present study, SWATH-MS is used as a tool for the robust identification and quantification of breast tissue proteins. SWATH-MS data show that OLFM4 expression is higher in DCIS than in invasive breast cancer. In-depth analysis of the breast tumor proteome show that OLFM4 is a favorable pronostic marker. Serum OLFM4 levels in peripheral blood are also analyzed by ELISA in 825 cases, including 94 cases of healthy individuals, 61 cases of non-invasive breast tumor (DCIS) and 670 cases of breast cancer (BC). It is found that serum OLFM4 levels are significantly higher in the DCIS cohort and in the breast cancer cohort compared with the healthy controls. This result suggests that circulating OLFM4 could be an interesting biomarker of early breast cancer. Data are available via ProteomeXchange with identifier PXD014194.

Olfactomedin 4 downregulation is associated with tumor initiation, growth and progression in human prostate cancer

The olfactomedin 4 (OLFM4) gene has been analyzed as a tumor‐suppressor gene and a putative biomarker in many cancers. In our study, we analyzed the relationship of OLFM4 expression with clinicopathological features and with CpG site methylation in the OLFM4 gene promoter region in human primary prostate adenocarcinoma. OLFM4 protein expression was significantly reduced in prostate cancer tissue compared to adjacent normal tissue and was further significantly reduced in more advanced cancers. Bioinformatic studies with clinical datasets revealed that primary prostate adenocarcinoma patients with reduced OLFM4 mRNA expression exhibited higher Gleason scores and higher preoperative serum prostate‐specific antigen levels, as well as lower recurrence‐free survival. Three of the eight CpG sites in the OLFM4 gene promoter region were hypermethylated in cancerous prostate cells compared to adjacent normal cells, and reduced methylation of eight CpG sites was associated with increased OLFM4 mRNA expression in RWPE1 and PC‐3 cells. Furthermore, knockdown of OLFM4 gene expression was associated with enhanced epithelial–mesenchymal transition (EMT)‐marker expression in RWPE immortalized normal prostate cells. In contrast, restoration of OLFM4 expression in PC‐3 and DU145 prostate cancer cells lacking OLFM4 significantly inhibited both EMT‐marker expression and tumor cell growth in in vitro and in vivo models, indicating that OLFM4 may play a tumor‐suppressor role in inhibiting the EMT program, as well as tumor initiation and growth, in prostate cells. Taken together, these findings suggest that OLFM4 plays an important tumor‐suppressor role in prostate cancer progression and might be useful as a novel candidate biomarker for prostate cancer.

What's new?

Altered expression of the OLFM4 gene appears to be involved in many cancers. In this study of prostate cancers, the authors found that OLFM4 can suppress tumor initiation, growth and progression. Downregulation of OLFM4 was associated with higher serum PSA levels, higher Gleason scores, and lower recurrence‐free survival in prostate cancer patients. These results indicate that OLFM4 may play an important tumor‐suppressor role in the progression of prostate cancer, and may provide a novel prognostic biomarker for prostate cancer treatment.

Olfactomedin 4 expression and functions in innate immunity, inflammation, and cancer

Olfactomedin 4 (OLFM4) is an olfactomedin domain-containing glycoprotein. Multiple signaling pathways and factors, including NF-κB, Wnt, Notch, PU.1, retinoic acids, estrogen receptor, and miR-486, regulate its expression. OLFM4 interacts with several other proteins, such as gene associated with retinoic-interferon-induced mortality 19 (GRIM-19), cadherins, lectins, nucleotide oligomerization domain-1 (NOD1) and nucleotide oligomerization domain-2 (NOD2), and cathepsins C and D, known to regulate important cellular functions. Recent investigations using Olfm4-deficient mouse models have provided important clues about its in vivo biological functions. Olfm4 inhibited Helicobacter pylori-induced NF-κB pathway activity and inflammation and facilitated H. pylori colonization in the mouse stomach. Olfm4-deficient mice exhibited enhanced immunity against Escherichia coli and Staphylococcus aureus infection. Olfm4 deletion in a chronic granulomatous disease mouse model rescued them from S. aureus infection. Olfm4 deletion in mice treated with azoxymethane/dextran sodium sulfate led to robust intestinal inflammation and intestinal crypt hyperplasia. Olfm4 deletion in Apc (Min/+) mice promoted intestinal polyp formation as well as adenocarcinoma development in the distal colon. Further, Olfm4-deficient mice spontaneously developed prostatic epithelial lesions as they age. OLFM4 expression is correlated with cancer differentiation, stage, metastasis, and prognosis in a variety of cancers, suggesting its potential clinical value as an early-stage cancer marker or a therapeutic target. Collectively, these data suggest that OLFM4 plays important roles in innate immunity against bacterial infection, gastrointestinal inflammation, and cancer. In this review, we have summarized OLFM4's initial characterization, expression, regulation, protein interactions, and biological functions.

The clinical significance and biological function of olfactomedin 4 in triple negative breast cancer

Olfactomedin 4 abnormal expression has been observed in several types of human cancer, but the status of olfactomedin 4 in triple negative breast cancer is still unknown. The aim of our study is to explore the clinical significance and biological function of olfactomedin 4 in triple negative breast cancer. The mRNA and protein expression of olfactomedin 4 in triple negative breast cancer tissues and cell lines was detected, and the correlation between olfactomedin 4 expression and clinicopathological factors was analyzed by immunohistochemistry. The biological function of olfactomedin 4 on tumor-metastasis was explored by Transwell migration assay and invasion assay in vitro. In our results, olfactomedin 4 mRNA and protein expression is decreased in triple-negative breast cancer tissues and cell lines. Olfactomedin 4 protein low-expression associated with lymph node metastasis, distant metastasis, clinical stage and poor prognosis of triple-negative breast cancer patients. Up-regulation of olfactomedin 4 suppresseed triple-negative breast cancer cells migration and invasion, and reduced cell metastasis-associated protein MMP 9 expression. In conclusion, olfactomedin 4 is a novel biomarker of triple-negative breast cancer for predicting prognosis and developing targeted molecular therapies.