Expression of TMPRSS4 in non-small cell lung cancer and its modulation by hypoxia

TMPRSS4, a type II transmembrane serine protease, as a potential therapeutic target in cancer

Proteases are involved in almost all biological processes, implying their importance for both health and pathological conditions. Dysregulation of proteases is a key event in cancer. Initially, research identified their role in invasion and metastasis, but more recent studies have shown that proteases are involved in all stages of cancer development and progression, both directly through proteolytic activity and indirectly via regulation of cellular signaling and functions. Over the past two decades, a novel subfamily of serine proteases called type II transmembrane serine proteases (TTSPs) has been identified. Many TTSPs are overexpressed by a variety of tumors and are potential novel markers of tumor development and progression; these TTSPs are possible molecular targets for anticancer therapeutics. The transmembrane protease serine 4 (TMPRSS4), a member of the TTSP family, is upregulated in pancreatic, colorectal, gastric, lung, thyroid, prostate, and several other cancers; indeed, elevated expression of TMPRSS4 often correlates with poor prognosis. Based on its broad expression profile in cancer, TMPRSS4 has been the focus of attention in anticancer research. This review summarizes up-to-date information regarding the expression, regulation, and clinical relevance of TMPRSS4, as well as its role in pathological contexts, particularly in cancer. It also provides a general overview of epithelial-mesenchymal transition and TTSPs.

Immunouniverse of SARS-CoV-2

SARS-CoV-2 virus has become a global health problem that has caused millions of deaths worldwide. The infection can present with multiple clinical features ranging from asymptomatic or mildly symptomatic patients to patients with severe or critical illness that can even lead to death. Although the immune system plays an important role in pathogen control, SARS-CoV-2 can drive dysregulation of this response and trigger severe immunopathology. Exploring the mechanisms of the immune response involved in host defense against SARS-CoV-2 allows us to understand its immunopathogenesis and possibly detect features that can be used as potential therapies to eliminate the virus. The main objective of this review on SARS-CoV-2 is to highlight the interaction between the virus and the immune response. We explore the function and action of the immune system, the expression of molecules at the site of infection that cause hyperinflammation and hypercoagulation disorders, the factors leading to the development of pneumonia and subsequent severe acute respiratory distress syndrome which is the leading cause of death in patients with COVID-19.

The upregulation of TMPRSS4, partly ascribed to the downregulation of miR‑125a‑5p, promotes the growth of human lung adenocarcinoma via the NF‑κB signaling pathway

In this study, with the aid of microarray technology, transmembrane protease serine 4 (TMPRSS4), a novel member of the serine protease family, was found to be upregulated in the majority of lung adenocarcinoma (LUAD) tissues compared to normal lung tissues. Of note, the clinical significance of TMPRSS4 in LUAD has not yet been reported, at least to the best of our knowledge. Through immunohistochemistry assays, we found that TMPRSS4 was overexpressed in LUAD tissues and that the TMPRSS4 expression level was also proportionally associated with the AJCC clinical stage, T stage and pathological grade. Moreover, a high expression of TMPRSS4 was found to be associated with adverse outcomes and was a significant independent factors predicting a poor prognosis. To elucidate the possible mechanisms responsible for the overexpression of TMPRSS4, we examined at microRNAs (miRNAs or miRs), which are small non-coding RNAs commonly dysregulated in human malignancies and are known to promote carcinogenesis by interacting with other types of RNAs. By means of bioinformatics analysis, a miRNA potentially targeting TMPRSS4 mRNA, namely miR-125a-5p, was selected. Dual luciferase reporter gene assays were then performed to verify the interaction. The results of MTT assays and apoptotic assays revealed that miR-125a-5p significantly inhibited cell growth and enhanced apoptosis, and the silencing of TMPRSS4 had similar effects. Furthermore, we observed that either the overexpression of miR-125a-5p or the silencing of TMPRSS4 prevented the activation of the nuclear factor (NF)-κB signaling pathway. On the whole, our findings illustrate that TMPRSS4 may be a candidate oncogene and may thus serve as a prognostic biomarker for LUAD, and its overexpression may be partly ascribed to the downregulation of miR-125a-5p. The dysregulation of miR-125a-5p and TMPRSS4 affect the biological function of LUAD cells via the NF-κB signaling pathway. The miR-125a-5p/TMPRSS4/NF-κB axis may thus provide novel insight into the pathogenic mechanisms of LUAD and may be used in the development of novel treatment strategies for LUAD.

Cell-surface marker discovery for lung cancer

Lung cancer is the leading cause of cancer deaths in the United States. Novel lung cancer targeted therapeutic and molecular imaging agents are needed to improve outcomes and enable personalized care. Since these agents typically cannot cross the plasma membrane while carrying cytotoxic payload or imaging contrast, discovery of cell-surface targets is a necessary initial step. Herein, we report the discovery and characterization of lung cancer cell-surface markers for use in development of targeted agents. To identify putative cell-surface markers, existing microarray gene expression data from patient specimens were analyzed to select markers with differential expression in lung cancer compared to normal lung. Greater than 200 putative cell-surface markers were identified as being overexpressed in lung cancers. Ten cell-surface markers (CA9, CA12, CXorf61, DSG3, FAT2, GPR87, KISS1R, LYPD3, SLC7A11 and TMPRSS4) were selected based on differential mRNA expression in lung tumors vs. non-neoplastic lung samples and other normal tissues, and other considerations involving known biology and targeting moieties. Protein expression was confirmed by immunohistochemistry (IHC) staining and scoring of patient tumor and normal tissue samples. As further validation, marker expression was determined in lung cancer cell lines using microarray data and Kaplan–Meier survival analyses were performed for each of the markers using patient clinical data. High expression for six of the markers (CA9, CA12, CXorf61, GPR87, LYPD3, and SLC7A11) was significantly associated with worse survival. These markers should be useful for the development of novel targeted imaging probes or therapeutics for use in personalized care of lung cancer patients.

Overexpression of TMPRSS4 promotes tumor proliferation and aggressiveness in breast cancer

Transmembrane protease serine 4 (TMPRSS4) is a novel type II transmembrane serine protease that is overexpressed in various types of human cancers and has an important function in cancer progression. However, there is a paucity of data available regarding the biological effects of TMPRSS4 on breast cancer (BC) cells and the underlying mechanisms. In this study, expression of TMPRSS4 in BC tissues was detected by immunohistochemistry. The relationship between TMPRSS4 expression and clinicopathological characteristics as well as prognosis was evaluated. The effects of TMPRSS4 on cell proliferation, migration and invasion were investigated in BC cell lines in vitro. Additionally, RT-qPCR and western blot analysis were used to determine the expressions of epithelial-mesenchymal transition (EMT) biomarkers and TMPRSS4 in BC cell lines. We found that TMPRSS4 was overexpressed in BC tissues and its expression level was closely correlated with tumor size, histological grade, lymph node metastasis, clinical stage as well as poor survival (all P<0.05) and could be recognized as an independent prognostic factor for BC patients. Overexpression of TMPRSS4 promoted the proliferation, migration and invasion of BC cells in vitro. Moreover, TMPRSS4 knockdown significantly enhanced the expression of E-cadherin and claudin-1 and inhibited the expression of vimentin and Slug, indicating suppression of EMT. Our results suggest that TMPRSS4 plays a crucial role in the progression of BC. Moreover, TMPRSS4 overexpression promoted the proliferation, invasion and migration of BC cells by possibly inducing EMT. To conclude, TMPRSS4 may be a potential therapeutic target for cancer treatment.

Epithelial Sodium Channel-Mediated Sodium Transport Is Not Dependent on the Membrane-Bound Serine Protease CAP2/Tmprss4

The membrane-bound serine protease CAP2/Tmprss4 has been previously identified in vitro as a positive regulator of the epithelial sodium channel (ENaC). To study its in vivo implication in ENaC-mediated sodium absorption, we generated a knockout mouse model for CAP2/Tmprss4. Mice deficient in CAP2/Tmprss4 were viable, fertile, and did not show any obvious histological abnormalities. Unexpectedly, when challenged with sodium-deficient diet, these mice did not develop any impairment in renal sodium handling as evidenced by normal plasma and urinary sodium and potassium electrolytes, as well as normal aldosterone levels. Despite minor alterations in ENaC mRNA expression, we found no evidence for altered proteolytic cleavage of ENaC subunits. In consequence, ENaC activity, as monitored by the amiloride-sensitive rectal potential difference (ΔPD), was not altered even under dietary sodium restriction. In summary, ENaC-mediated sodium balance is not affected by lack of CAP2/Tmprss4 expression and thus, does not seem to directly control ENaC expression and activity in vivo.

Methylation-induced downregulation of TFPI-2 causes TMPRSS4 overexpression and contributes to oncogenesis in a subset of non-small-cell lung carcinoma

We identified transmembrane protease, serine 4 (TMPRSS4) as a putative, druggable target by screening surgically resected samples from 90 Japanese non-small-cell lung cancer (NSCLC) patients using cDNA microarray. TMPRSS4 has two druggable domains and was upregulated in 94.5% of the lung cancer specimens. Interestingly, we found that TMPRSS4 expression was associated with tissue factor pathway inhibitor 2 (TFPI-2) expression in these clinical samples. In contrast to TMPRSS4, TFPI-2 expression was downregulated in NSCLC samples. The in vitro induction of TFPI-2 in lung cancer cell lines decreased the expression of TMPRSS4mRNA levels. Reporter assay showed that TFPI-2 inhibited transcription of TMPRSS4, although partially. Knockdown of TMPRSS4 reduced the proliferation rate in several lung cancer cell lines. When lung cancer cell lines were treated with 5-aza-2′-deoxycytidine or trichostatin A, their proliferation rate and TMPRSS4mRNA expression levels were also reduced through the upregulation of TFPI-2 by decreasing its methylation in vitro. The TFPI-2 methylation level in the low TMPRSS4 group appeared to be significantly low in NSCLC samples (P = 0.02). We found a novel molecular mechanism that TFPI-2 negatively regulates cell growth by inhibiting transcription of TMPRSS4. We suggest that TMPRSS4 is upregulated by silencing of TFPI-2 through aberrant DNA methylation and contributes to oncogenesis in NSCLC.

Clinical significance of TMPRSS4 in prostate cancer

Transmembrane protease serine 4 (TMPRSS4) is a type-II transmembrane serine protease that plays an important role in the migration of cancer cells. This study aimed to investigate both the expression of TMPRSS4 and its clinical significance in prostate cancer. The expression of TMPRSS4 was evaluated in 73 pairs of prostate cancer and adjacent non-cancerous tissues by immunohistochemistry. The level of TMPRSS4 in prostate cancer tissues was significantly higher than that in adjacent non-cancerous tissues. High TMPRSS4 expression was significantly associated with advanced TNM stage and LNM. No association between TMPRSS4 expression and progression-free survival was observed in all patients. Stratified analyses according to clinical features revealed that patients with low TMPRSS4 expression had poor prognosis compared with those with high TMPRSS4 expression in subjects not receiving neoadjuvant chemotherapy. In conclusion, TMPRSS4 showed abnormal expression in prostate cancer tissues. TMPRSS4 may be a potential prognostic biomarker for prostate cancer patients who did not undergo neoadjuvant chemotherapy.

Lung cancer transcriptomes refined with laser capture microdissection

We evaluated the importance of tumor cell selection for generating gene signatures in non-small cell lung cancer. Tumor and nontumor tissue from macroscopically dissected (Macro) surgical specimens (31 pairs from 32 subjects) was homogenized, extracted, amplified, and hybridized to microarrays. Adjacent scout sections were histologically mapped; sets of approximately 1000 tumor cells and nontumor cells (alveolar or bronchial) were procured by laser capture microdissection (LCM). Within histological strata, LCM and Macro specimens exhibited approximately 67% to 80% nonoverlap in differentially expressed (DE) genes. In a representative subset, LCM uniquely identified 300 DE genes in tumor versus nontumor specimens, largely attributable to cell selection; 382 DE genes were common to Macro, Macro with preamplification, and LCM platforms. RT-qPCR validation in a 33-gene subset was confirmatory (ρ = 0.789 to 0.964, P = 0.0013 to 0.0028). Pathway analysis of LCM data suggested alterations in known cancer pathways (cell growth, death, movement, cycle, and signaling components), among others (eg, immune, inflammatory). A unique nine-gene LCM signature had higher tumor-nontumor discriminatory accuracy (100%) than the corresponding Macro signature (87%). Comparison with Cancer Genome Atlas data sets (based on homogenized Macro tissue) revealed both substantial overlap and important differences from LCM specimen results. Thus, cell selection via LCM enhances expression profiling precision, and confirms both known and under-appreciated lung cancer genes and pathways.

Membrane Proteins Involved in Epithelial-Mesenchymal Transition and Tumor Invasion: Studies on TMPRSS4 and TM4SF5

The epithelial-mesenchymal transition (EMT) is one mechanism by which cells with mesenchymal features can be generated and is a fundamental event in morphogenesis. Recently, invasion and metastasis of cancer cells from the primary tumor are now thought to be initiated by the developmental process termed the EMT, whereby epithelial cells lose cell polarity and cell-cell interactions, and gain mesenchymal phenotypes with increased migratory and invasive properties. The EMT is believed to be an important step in metastasis and is implicated in cancer progression, although the influence of the EMT in clinical specimens has been debated. This review presents the recent results of two cell surface proteins, the functions and underlying mechanisms of which have recently begun to be demonstrated, as novel regulators of the molecular networks that induce the EMT and cancer progression.

Clinical implication of TMPRSS4 expression in human gallbladder cancer

Altered expression of transmembrane protease/serine 4 (TMPRSS4) is observed in various types of human cancers. However, the clinical significance of TMPRSS4 expression in gallbladder cancer (GBC) remains largely unknown. The present study aims to explore the clinicopathological significance and prognostic value of TMPRSS4 in GBC. The levels of TMPRSS4 mRNA and protein in GBC tissues and adjacent noncancerous tissues were evaluated by quantitative reverse-transcriptase polymerase chain reaction and immunohistochemistry. To investigate the correlations between TMPRSS4 and the clinicopathological features of GBC, the expression of TMPRSS4 in 97 patients with GBC were detected by immunohistochemistry. The correlation of TMPRSS4 expression with patients' survival rate was assessed by Kaplan-Meier and Cox regression. Our results showed that the expression levels of TMPRSS4 mRNA and protein in GBC tissues were both significantly higher than those in adjacent noncancerous tissues. Immunohistochemical staining revealed that high TMPRSS4 expression was closely correlated with tumor size (P=0.032), histological grade (P=0.002), pathologic T stage (P=0.005), clinical stage (P=0.013), and lymph node metastasis (P=0.003). Moreover, the results of Kaplan-Meier analysis indicated that a high expression level of TMPRSS4 resulted in a significantly poor prognosis of GBC patients. Multivariate analysis showed that the status of TMPRSS4 expression was an independent prognostic factor for GBC patients. Our results showed that TMPRSS4 plays a key role in GBC and therefore may provide an opportunity for developing a novel therapeutic target as well as a prognostic marker in GBC.

TMPRSS4 correlates with colorectal cancer pathological stage and regulates cell proliferation and self-renewal ability

Transmembrane protease/serine 4 (TMPRSS4) is a member of the type II transmembrane serine protease (TTSP) family and it was found highly expressed in several cancers. This study aims to evaluate the expression of TMPRSS4 in colorectal cancer (CRC) and investigate its role in proliferation and self-renewal of colon cancer cells. qRT-PCR and immunohistochemistry were used to detect the mRNA and protein expression level of TMRPSS4 in CRC samples respectively. Loss of function assay was conducted with RNAi technique. Cell proliferation was done with WST-8 assay; cell apoptosis and cell cycle analysis were performed with flow cytometry; invasion and migration were done with transwell assay. Plate and soft agarose clonogenic assays were used to detect clone-formation ability. CD44 and CD133 expressions were analyzed by flow cytometry and western blot. We found that TMPRSS4 was highly expressed in CRC tissues both at mRNA and protein level and correlated with pathological stage. Knockdown of TMPRSS4 in highly expressed colon cancer cell line HCT116 resulted in inhibition of cell proliferation, induction of cell apoptosis and suppression of invasion and migration; moreover, knockdown of TMPRSS4 suppressed the in vitro clone-formation ability of HCT116 and reduced the expressions of CD44 and CD133. The findings in this research showed that TMPRSS4 was associated with CRC stage and regulated the proliferation and self-renewal ability of colon cancer cells; TMRPSS4 was involved in the development and progression of CRC.

High expression level of TMPRSS4 predicts adverse outcomes of colorectal cancer patients

Transmembrane protease/serine 4 (TMPRSS4), a member of the type II transmembrane serine protease family, is highly expressed in some human cancers and involved in the EMT regulation of cancer cells. The prognostic value of TMPRSS4 in colorectal cancer (CRC) has not been discussed. This study aims to evaluate the association between TMPRSS4 expressions and survival in CRC patients. Immunohistochemistry revealed high expression of TMPRSS4 in 69/122 CRC samples, compared with 14/47 in normal tissues (P < 0.01). Correlation analysis showed high expression of TMPRSS4 was significantly associated with advanced TNM stage (P = 0.011), pT (P = 0.019), pN (P = 0.035), and pM status (P = 0.004). Higher TMPRSS4 predicted shorter overall survival (OS) and disease-free survival (DFS) in CRC patients (P < 0.01, both). Moreover, both TMPRSS4 expression and TNM stage were independent predictive factors of OS and DFS in Cox regression analysis. The findings in our study demonstrated the potential value of TMPRSS4 expression level as a prognostic biomarker for CRC patients.

TMPRSS4 as a poor prognostic factor for triple-negative breast cancer

Triple-negative breast cancer (TNBC) is characterized by the lack of immunohistochemical staining for estrogen receptors (ER), progesterone receptors (PR), and lack of overexpression or amplification of human epidermal growth factor receptor 2 (HER2). Our aim was to investigate the expression of transmembrane protease, serine 4 (TMPRSS4) in TNBC patients and its possible relationship to the outcome of the disease. A total of 72 TNBC patients and 109 non-TNBC patients who were diagnosed between 2003 and 2008 were enrolled in this study. Immunohistochemistry was used to compare the expression pattern of TMPRSS4 in TNBC and non-TNBC groups, and the prognostic significance was assessed by Kaplan-Meier analysis and Cox proportional hazards regression in TNBC patients. The rate of high expression of TMPRSS4 was significantly higher in TNBC group than that in non-TNBC group. High expression of TMPRSS4 was significantly correlated with lymph node metastasis, histological grade, and tumor size. TNBC patients with high TMPRSS4 expression showed the poorer overall survival (OS) and disease-free survival (DFS) than those patients with low TMPRSS4 expression. In multivariate analysis, only lymph node metastasis and TMPRSS4 expression were the independent prognostic factors for OS and DFS in TNBC. Our study provides evidence that TMPRSS4 expression is associated with lymph node metastasis, tumor size, and histological grade in TNBC patients, and also is an independent prognostic factor for TNBC.