Claudins as biomarkers of differential diagnosis and prognosis of tumors

Evidence to Date on the Therapeutic Potential of Zolbetuximab in Advanced Gastroesophageal Adenocarcinoma

Gastric adenocarcinoma (GAC) continues to be a prevalent worldwide malignancy and a leading cause of cancer death, and it is frequently cited as incurable. Targeted therapy in GAC has lagged behind other solid tumors. The human epidermal growth factor receptor-2 (HER-2) represented the single target in GACs for many years, seen in approximately 20% of patients with advanced GAC. Recent advances in management now include the addition of immunotherapy checkpoint inhibition to select front-line advanced GACs. Unfortunately, outcomes remain poor for most patients. We anticipate finding a key to future discoveries in GACs in next-generation sequencing and more targeted approaches. Claudin 18.2 (CLDN18.2) has emerged as a therapeutic target in GACs. CLDN18.2 is reportedly expressed in 14-87% of GACs, and CLDN18.2 is available for monoclonal antibody (mAb) binding as it is expressed on the outer cell membrane. Here, we review the exploration of CLDN18.2 as a target in GACs via the use of zolbetuximab (IMAB362). Zolbetuximab is now under priority FDA review for GACs, and we eagerly await the review outcome.

Claudin expression in pulmonary adenoid cystic carcinoma and mucoepidermoid carcinoma

Background: Although the expression of tight junction protein claudins (CLDNs) is well known in common histological subtypes of lung cancer, it has not been investigated in rare lung cancers. The aim of our study was to examine the expression of different CLDNs in pulmonary salivary gland tumors. Methods: 35 rare lung cancers including pathologically confirmed 12 adenoid cystic carcinomas (ACCs) and 23 mucoepidermoid carcinomas (MECs) were collected retrospectively. Immunohistochemical (IHC) staining was performed on formalin fixed paraffin embedded (FFPE) tumor tissues, and CLDN1, -2, -3, -4, -5, -7, and -18 protein expressions were analyzed. The levels of immunopositivity were determined with H-score. Certain pathological characteristics of ACC and MEC samples (tumor grade, presence of necrosis, presence of blood vessel infiltration, and degree of lymphoid infiltration) were also analyzed. Results: CLDN overexpression was observed in both tumor types, especially in CLDN2, -7, and -18 IHC. Markedly different patterns of CLDN expression were found for ACC and MEC tumors, especially for CLDN1, -2, -4, and -7, although none of these trends remained significant after correction for multiple testing. Positive correlations between expressions of CLDN2 and -5, CLDN3 and -4, and CLDN5 and -18 were also demonstrated. Tumors of never-smokers presented lower levels of CLDN18 than tumors of current smokers (p-value: 0.003). Conclusion: This is the first study to comprehensively describe the expression of different CLDNs in lung ACC and MEC. Overexpression of certain CLDNs may pave the way for targeted anti-claudin therapy in these rare histological subtypes of lung cancer.

Carvacrol attenuated lipopolysaccharide-induced intestinal injury by down-regulating TLRs gene expression and regulating the gut microbiota in rabbit

Carvacrol (CAR) is a plant extract that has been reported to enhance antioxidant activity in animals. However, the effect of CAR on the intestinal health of rabbits is poorly understood. Here, we investigated whether CAR exerts protective effects on the intestinal health of rabbits following lipopolysaccharide (LPS) challenge and whether these effects were mediated via the reduction of intestinal inflammation and the regulation of the intestinal flora. Intestinal damage was assessed in LPS-challenged rabbits treated or not with CAR. The serum levels of inflammatory factors were assessed by enzyme-linked immunosorbent assay. Histopathological changes in the ileum and cecum were examined using hematoxylin and eosin staining. The relative gene expression levels of inflammatory factors and tight junction proteins in the rabbit cecum were determined by qRT-PCR. High-throughput sequencing analysis of the microbial 16S rRNA gene was performed using the Illumina NovaSeq Platform. The results showed that CAR can prevent intestinal inflammation and damage as well as mitigate gut dysbiosis in rabbits following LPS challenge. Our study provides a theoretical reference for the application of dietary CAR in rabbit production.

The roles of 68 Ga-PSMA PET/CT and 18 F-FDG PET/CT imaging in patients with triple-negative breast cancer and the association of tissue PSMA and claudin 1, 4, and 7 levels with PET findings

AIM

Aim of study is to compare the results of Gallium-68-prostate-specific membrane antigen ( 68 Ga-PSMA) and 18 F-fluorodeoxyglucose ( 18 F-FDG) positron emission tomography(PET)/computed tomography (CT), to evaluate the correlation between PET findings and the level of PSMA, Claudin (Clau) 1, 4, and 7 receptors obtained by immunohistochemical (IHC) analysis, and to determine potential predictive and prognostic values in TNBC.

METHODS

Forty-seven lesions of 42 subjects diagnosed TNBC both underwent PET/CT scan for preoperative staging/restaging were prospectively included study. PSMA, Clau 1, 4, and 7 expressions were IHC evaluated from the biopsy samples of the primary tumor (PT). Maximum standardized uptake value(SUV max) of the PT, lymph node, and distant organ metastases (DOMs) on 18 F-FDG and 68 Ga-PSMA PET/CT were compared with PSMA, Clau 1, 4, and 7 receptor expressions.

RESULTS

IHC analyses on 29 BC lesions to demonstrate Clau expression showed 86% (25/29) Clau 1, 86% (25/29) Clau 4, 45% (13/29) Clau 7, and 48% (14/29) PSMA-positive. The mean DOM (SUVmax) was 15.5 ± 11.6 for 18 F-FDG and 6.0 ± 2.9 for 68 Ga-PSMA. Axial diameter of BC PT had a significant positive correlation with 18 F-FDG SUVmax, 68 Ga-PSMA SUVmax, and PSMA scores. BC lesions 68 Ga-PSMA SUVmax had a significant negative correlation with the Ki-67 index. Axial diameter of the primary tumor had significant negative correlation with Clau 7 scores ( r  = -0.409, P  = 0.034). Absence of Clau 1 expression found to significantly increase the rate of DOM (100% vs. 28%) ( P  = 0.014). All patients with axillary lymph node (ALN) metastases ( n  = 17, 100%) exhibited Clau 4 positivity ( P  = 0.021). The presence of PSMA expression observed to significantly increase the rate of ALN metastases (64.7% vs. 25%) ( P  = 0.035).

CONCLUSION

Confirming PSMA expression with PET imaging would be significant as PSMA, a theranostic agent, may be a considerable potential agent for radionuclide treatment strategies, in addition to its additional diagnostic contribution to FDG, especially in patients with metastatic TNBC, which is an aggressive, heterogeneous disease.

Double mutation of claudin‐1 and claudin‐3 causes alopecia in infant mice

Hair follicles (HFs) undergo cyclic phases of growth, regression, and rest in association with hair shafts to maintain the hair coat. Nonsense mutations in the tight junction protein claudin (CLDN)-1 cause hair loss in humans. Therefore, we evaluated the roles of CLDNs in hair retention. Among the 27 CLDN family members, CLDN1, CLDN3, CLDN4, CLDN6, and CLDN7 were expressed in the inner bulge layer, isthmus, and sebaceous gland of murine HFs. Hair phenotypes were observed in Cldn1 weaker knockdown and Cldn3-knockout (Cldn1^Δ/Δ Cldn3^-/- ) mice. Although hair growth was normal, Cldn1^Δ/Δ Cldn3^-/- mice showed striking hair loss in the first telogen. Simultaneous deficiencies in CLDN1 and CLDN3 caused abnormalities in telogen HFs, such as an aberrantly layered architecture of epithelial cell sheets in bulges with multiple cell layers, mislocalization of bulges adjacent to sebaceous glands, and dilated hair canals. Along with the telogen HF abnormalities, which shortened the hair retention period, there was an enhanced proliferation of the epithelium surrounding HFs in Cldn1^Δ/Δ Cldn3^-/- mice, causing accelerated hair regrowth in adults. Our findings suggested that CLDN1 and CLDN3 may regulate hair retention in infant mice by maintaining the appropriate layered architecture of HFs, a deficiency of which can lead to alopecia.

[Is there a claudin-low phenotype of breast cancer?]

The novel molecular subtype of breast cancer (BC), named "claudin-low", was described in 2007. It was characterized by the consistently low expression of genes involved in the formation of epithelial tight junctions in combination with the high activation of genes associated with the epithelial-to-mesenchymal transition, as well as tumor stem cell markers. The similar claudin- low subtype was later identified at the transcriptional level in bladder cancer, gastric cancer, and serous ovarian cancer. However, only in relation to BC, attempts were made to create a surrogate panel for immunohistochemical identification of this subtype in a manner like the intrinsic molecular BC subtypes identified using three main markers, such as ER, PR, and HER-2. At the same time, the ambiguity in the expression of claudins among the subtypes of BC, which is defined by various authors at the immunohistochemical level, as well as the absence of both the confirmed set of immunohistochemical criteria and a unified approach to their assessment, complicate these efforts. The purpose of the review is to show that the immunohistochemical identification of claudin-low subtype of BC is a separate problem that has significant limitations, needs standardization and has not yet reached diagnostic value.