Expression of Claudin-9 (CLDN9) in Breast Cancer, the Clinical Significance in Connection with Its Subcoat Anchorage Proteins ZO-1 and ZO-3 and Impact on Drug ResistanceZhuang, Martin, Ruge
et alBiomedicines (2023) 11 (12)
Abstract: (1) Introduction: Claudin-9 (CLDN9) is a member of the claudin protein family, a critical transmembrane protein family for tight junctions that are implemented in the progression of numerous cancer types. The present study investigated the role that CLDN9, along with the subcoat proteins, Zonula Occludens (ZOs), plays in clinical breast cancer and subsequent impact on drug response of patients. (2) Methods: CLDN9 protein and CLDN9 transcript were determined and correlated with clinical and pathological indicators, together with the status of hormonal receptors. The levels of CLDN9 transcript were also assessed against the therapeutic responses of the patients to chemotherapies by using a dataset from the TCGA database. Breast cancer cell models, representing different molecular subtypes of breast cancer, with differential expression of CLDN9 were created and used to assess the biological impact and response to chemotherapeutic drugs. (3) Results: Breast cancer tissues expressed significantly higher levels of the CLDN9, with the high levels being associated with shorter survival. CLDN9 was significantly correlated with its anchorage proteins ZO-1 and ZO-3. Integrated expression of CLDN9, ZO-1 and ZO-3 formed a signature that was significantly linked to overall survival (OS) (p = 0.013) and relapse-free survival (RFS) (p = 0.024) in an independent matter. CLDN9 transcript was significantly higher in patients who were resistant to chemotherapies (p < 0.000001). CLDN9 connection to chemoresistance was particularly prominent in patients of ER-positive (ER(+)), Her-2-negative((Her-2(-)), ER(+)/Her-2(-) and triple-negative breast cancers (TNBCs), but not in patients with HER-2-positive tumors. In Her-2-negative MCF7 and MDA-MB-231 cancer cells, loss of CLDN9 significantly increased sensitivity to several chemotherapeutic drugs including paclitaxel, gemcitabine and methotrexate, which was not seen in Her-2(+) SKBR3 cells. However, suppressing Her-2 using neratinib, a permanent Her-2 inhibitor, sensitized cellular response to these chemodrugs in cells with CLDN9 knockdown. (4) Conclusions: CLDN9 is an important prognostic indicator for patients with breast cancer and also a pivotal factor in assessing patient responses to chemotherapies. Her-2 is a negating factor for the treatment response prediction value by CLDN9 and negating Her-2 and CLDN9 may enhance breast cancer cellular response to chemotherapeutic drugs.
The correlation among Claudin-9, Tyrosine kinase-2, and Signal transducers and activators of transcription-3 expressions in non-functioning pituitary adenoma and invasivenessYasen, Tuoheti, Tu
et alNeuro Endocrinol Lett (2023) 44 (8), 537-546
Abstract: Deeper studies on the pathological mechanism associated with invasiveness of non-functioning pituitary adenoma (NFPA) is imperative to find better treatments. This research was preliminarily conducted to investigate the correlation between the expression of Claudin-9 (CLDN9), Tyrosine kinase-2 (TYK2), Signal transducers and activators of transcription-3 (STAT3) and invasiveness in NFPA to illustrate the pathological mechanism.Clinical data and surgical specimens of 12 patients with NFPA were collected and divided into invasive and non-invasive NFPA groups, comprising six patients for each group. CLDN9, TYK2 and STAT3 transcription and expression levels in the NFPA tissues of the two groups were detected by quantitative real-time polymerase chain reaction (qRT-PCR), Western blotting (WB) and immunohistochemistry (IHC). The lentiviral plasmid transfection technique was used to develop a rat pituitary tumour GT1-1 cell line null control group (NC) and CLDN9-overexpressed experimental group (OE-CLDN9), and TYK2 and STAT3 transcription levels in the NC and OE-CLDN9 cell groups were detected using qRT-PCR.The CLDN9 and STAT3 expressions were significantly higher in invasive than in non-invasive NFPA tissues, whereas the TYK2 expression in invasive NFPA tissues was significantly lower than that in non-invasive NFPA (p < 0.001); The STAT3 upregulated (p < 0.001) and the TYK2 downregulated (p < 0.01) after the CLDN9 overexpression.Upregulated CLDN9 may increase the NFPA invasiveness through STAT3. In addition, low TYK2 expression might enhance the invasiveness in NFPA, which needs further studies to confirm. These results could provide a promising research leads for targeted treatment of NFPA.
Pharmacological Activity of Matrine in Inhibiting Colon Cancer Cells VM Formation, Proliferation, and Invasion by Downregulating Claudin-9 Mediated EMT Process and MAPK Signaling PathwayDu, Lin, Ding
et alDrug Des Devel Ther (2023) 17, 2787-2804
Abstract: Matrine (Mat), the main active ingredient of traditional Chinese herbal plant Sophora flavescens Ait, has significant antitumor effects, but its pharmacological mechanism on colon cancer (CC) remains unclear. This study aimed to investigate the therapeutic effect of Mat on CC as well as the potential mechanism.The vasculogenic mimicry (VM) of CC cells was observed by three-dimensional (3D) Matrigel cell culture. Cell proliferation, apoptosis, migration, invasion, and actin filament integrity were detected by CCK8, flow cytometry, wound healing, Transwell and Phalloidin staining assays. qRT-PCR and Western blotting were applied to detect the expression of EMT factors. RNA-sequencing was conducted to screen differentially expressed genes (DEGs), and the GO and KEGG pathway enrichment analyses were performed. Then, the expression of the key MAPK pathway genes and the target gene Claudin-9 (Cldn9) were analyzed. RNA interference was used to silence Cldn9 expression, and the effects of Cldn9 silencing and simultaneous treatment with Mat on VM formation, proliferation, apoptosis, invasion, and migration were investigated. Finally, the expression of EMT factors and MAPK pathway key genes was detected.CT26 cells formed the most typical VM structure. Mat disrupted the VM of CT26 cells, significantly suppressed their proliferation, migration, invasion, actin filament integrity, induced apoptosis, and inhibited EMT process. RNA-sequencing revealed 163 upregulated genes and 333 downregulated genes in Mat-treated CT26 cells, and the DEGs were significantly enriched in cell adhesion molecules and MAPK signaling pathways. Further confirmed that Mat significantly inhibited the phosphorylation levels of JNK and ERK, and the target gene Cldn9 was significantly upregulated in human CC tissues. Silencing Cldn9 markedly inhibited the VM, proliferative activity, invasiveness, and actin filament integrity of CT26 cells, blocked the EMT process, and downregulated the phosphorylation of JNK and ERK, whereas Mat intervention further strengthened the above trends.This study indicated that Mat may synergistically inhibit the EMT process and MAPK signaling pathway through downregulation Cldn9, thereby exerting pharmacological effects on inhibiting VM formation, proliferation, and invasion of CC cells.© 2023 Du et al.
Claudin‑9 is a novel prognostic biomarker for endometrial cancerEndo, Sugimoto, Kobayashi
et alInt J Oncol (2022) 61 (5)
Abstract: The tight‑junction protein claudin‑9 (CLDN9) is barely distributed in normal adult tissues but is ectopically expressed in various cancer types. Although multiple databases indicated upregulation of CLDN9 in endometrial cancers at the mRNA level, its protein expression and biological roles remain obscure. In the present study, the prognostic significance of CLDN9 expression in endometrial cancer was evaluated by immunohistochemical staining and semi‑quantification using formalin‑fixed paraffin‑embedded specimens obtained from 248 endometrial carcinoma cases. A total of 43 cases (17.3%) had high CLDN9 expression, whereas 205 cases (82.7%) exhibited low CLDN9 expression. The 5‑year disease‑specific survival rates in the high and low CLDN9 expression groups were 62.8 and 87.8% (P<0.001), respectively. In addition, multivariate analysis revealed that high CLDN9 expression was an independent prognostic factor (hazard ratio, 4.99; 95% CI, 1.96‑12.70; P<0.001). Furthermore, CLDN9 expression was significantly correlated with the expression of CLDN6 (P<0.001), which is the closest CLDN member to CLDN9 and a poor prognostic factor for endometrial carcinoma. The 5‑year disease‑specific survival rate of cases with CLDN6‑high/CLDN9‑high, CLDN6‑high/CLDN9‑low and CLDN6‑low/CLDN9‑high status was 30.0, 37.5 and 72.7%, respectively, whereas that of CLDN6‑low/CLDN9‑low was 89.8% (P=0.004). In conclusion, aberrant CLDN9 expression is a predictor of poor prognosis for endometrial cancer and may be utilized in combination with CLDN6 to achieve higher sensitivity.
膜杰作
Star Staining
