Correlation of immunoglobulin G expression and histological subtype and stage in breast cancer

A Comparative Analysis of the Immunoglobulin Repertoire in Leukemia Cells and B Cells in Chinese Acute Myeloid Leukemia by High-Throughput Sequencing

It is common knowledge that immunoglobulin (Ig) is produced by B lymphocytes and mainly functions as an antibody. However, it has been shown recently that myeloblasts from acute myeloid leukemia (AML) could also express Ig and that AML-Ig played a role in leukemogenesis and AML progression. The difference between Ig from myeloblasts and B cells has not been explored. Studying the characteristics of the Ig repertoire in myeloblasts and B cells will be helpful to understand the function and significance of AML-Ig. We performed 5' RACE-related PCR coupled with PacBio sequencing to analyze the Ig repertoire in myeloblasts and B cells from Chinese AML patients. Myeloblasts expressed all five classes of IgH, especially Igγ, with a high expression frequency. Compared with B-Ig in the same patient, AML-Ig showed different biased V(D)J usages and mutation patterns. In addition, the CDR3 length distribution of AML-Ig was significantly different from those of B-Ig. More importantly, mutations of AML-IgH, especially Igμ, Igα, and Igδ, were different from that of B-IgH in each AML patient, and the mutations frequently occurred at the sites of post-translational modification. AML-Ig has distinct characteristics of variable regions and mutations, which may have implications for disease monitoring and personalized therapy.

Bioinformatic analysis and experimental validation of six cuproptosis-associated genes as a prognostic signature of breast cancer

Background

Breast carcinoma (BRCA) is a life-threatening malignancy in women and shows a poor prognosis. Cuproptosis is a novel mode of cell death but its relationship with BRCA is unclear. This study attempted to develop a cuproptosis-relevant prognostic gene signature for BRCA.

Methods

Cuproptosis-relevant subtypes of BRCA were obtained by consensus clustering. Differential expression analysis was implemented using the 'limma' package. Univariate Cox and multivariate Cox analyses were performed to determine a cuproptosis-relevant prognostic gene signature. The signature was constructed and validated in distinct datasets. Gene set variation analysis (GSVA) and gene set enrichment analysis (GSEA) were also conducted using the prognostic signature to uncover the underlying molecular mechanisms. ESTIMATE and CIBERSORT algorithms were applied to probe the linkage between the gene signature and tumor microenvironment (TME). Immunotherapy responsiveness was assessed using the Tumor Immune Dysfunction and Exclusion (TIDE) web tool. Real-time quantitative PCR (RT-qPCR) was performed to detect the expressions of cuproptosis-relevant prognostic genes in breast cancer cell lines.

Results

Thirty-eight cuproptosis-associated differentially expressed genes (DEGs) in BRCA were mined by consensus clustering and differential expression analysis. Based on univariate Cox and multivariate Cox analyses, six cuproptosis-relevant prognostic genes, namely SAA1, KRT17, VAV3, IGHG1, TFF1, and CLEC3A, were mined to establish a corresponding signature. The signature was validated using external validation sets. GSVA and GSEA showed that multiple cell cycle-linked and immune-related pathways along with biological processes were associated with the signature. The results ESTIMATE and CIBERSORT analyses revealed significantly different TMEs between the two Cusig score subgroups. Finally, RT-qPCR analysis of cell lines further confirmed the expressional trends of SAA1, KRT17, IGHG1, and CLEC3A.

Conclusion

Taken together, we constructed a signature for projecting the overall survival of BRCA patients and our findings authenticated the cuproptosis-relevant prognostic genes, which are expected to provide a basis for developing prognostic molecular biomarkers and an in-depth understanding of the relationship between cuproptosis and BRCA.

Expression and Clinical Significance of Non B Cell-Derived Immunoglobulins in the Urinary System and Male Reproductive System

The urinary system comprises kidneys, ureters, bladder, and urethra with its primary function being excretion, referring to the physiological process of transporting substances that are harmful or surplus out of the body. The male reproductive system consists of gonads (testis), vas deferens, and accessory glands such as the prostate. According to classical immunology theory, the tissues and organs mentioned above are not thought to produce immunoglobulins (Igs), and any Ig present in the relevant tissues under physiological and pathological conditions is believed to be derived from B cells. For instance, most renal diseases are associated with uncontrolled inflammation caused by pathogenic Ig deposited in the kidney. Generally, these pathological Igs are presumed to be produced by B cells. Recent studies have demonstrated that renal parenchymal cells can produce and secrete Igs, including IgA and IgG. Glomerular mesangial cells can express and secrete IgA, which is associated with cell survival and adhesion. Likewise, human podocytes demonstrate the ability to produce and secrete IgG, which is related to cell survival and adhesion. Furthermore, renal tubular epithelial cells also express IgG, potentially involved in the epithelial-mesenchymal transition (EMT). More significantly, renal cell carcinoma, bladder cancer, and prostate cancer have been revealed to express high levels of IgG, which promotes tumour progression. Given the widespread Ig expression in the urinary and male reproductive systems, continued efforts to elucidate the roles of Igs in renal physiological and pathological processes are necessary.

The Expression of Non B Cell-Derived Immunoglobulins

Although V(D)J recombination and immunoglobulin (Ig) production are traditionally recognised to occur only in B lymphocytes and plasma cells, the expression of Igs in non-lymphoid cells, which we call non B cell-derived Igs (non B Igs), has been documented by growing studies. It has been demonstrated that non B-Igs can be widely expressed in most cell types, including, but not limited to, epithelial cells, cardiomyocytes, hematopoietic stem/progenitor cells, myeloid cells, and cells from immune-privileged sites, such as neurons and spermatogenic cells. In particular, malignant tumour cells express high level of IgG. Moreover, different from B-Igs that mainly localised on the B cell membrane and in the serum and perform immune defence function mainly, non B-Igs have been found to distribute more widely and play critical roles in immune defence, maintaining cell proliferation and survival, and promoting progression. The findings of non B-Igs may provide a wealthier breakthrough point for more therapeutic strategies for a wide range of immune-related diseases.

Expression and Function of Mammary Epithelial Cell-Derived Immunoglobulins

Over the past 20 years, increasing evidence has demonstrated that immunoglobulins (Igs) can be widely generated from non B cells, including normal and malignant mammary epithelial cells. In normal breast tissue, the expression of IgG and IgA has been identified in epithelial cells of mammary glands during pregnancy and lactation, which can be secreted into milk, and might participate in neonatal immunity. On the other hand, non B-IgG is highly expressed in breast cancer cells, correlating with the poor prognosis of patients with breast cancer. Importantly, a specific group of IgG, bearing a unique N-linked glycan on the Asn162 site and aberrant sialylation modification at the end of the novel glycan (referred to as sialylated IgG (SIA-IgG)), has been found in breast cancer stem/progenitor-like cells. SIA-IgG can significantly promote the capacity of migration, invasiveness, and metastasis, as well as enhance self-renewal and tumorigenicity in vitro and in vivo. These findings suggest that breast epithelial cells can produce Igs with different biological activities under physiological and pathological conditions. During lactation, these Igs could be the main source of milk Igs to protect newborns from pathogenic infections, while under pathological conditions, they display oncogenic activity and promote the occurrence and progression of breast cancer.

Comparison of Non B-Ig and B-Ig

Immunoglobulin (Ig) has been widely acknowledged to be produced solely by B-lineage cells. However, growing evidence has demonstrated the expression of Ig in an array of cancer cells, as well as normal cells including epithelial cells, epidermal cells, mesangial cells, monocytes, and neutrophils. Ig has even been found to be expressed in non-B cells at immune-privileged sites such as neurons and spermatogenic cells. Despite these non-B cell-derived Igs (non-B-Igs) sharing the same symmetric structures with conventional Igs (B-Igs), further studies have revealed unique characteristics of non-B-Ig, such as restricted variable region and aberrant glycosylation. Moreover, non-B-Ig exhibits properties of promoting malignant behaviours of cancer cells, therefore it could be utilised in the clinic as a potential therapeutic biomarker or target. The elucidation of the generation and regulation of non-B-Ig will certainly broaden our understanding of immunology.

Non B Cell-Derived Immunoglobulins in Lung Epithelial Cells and Lung Cancer

As the locus for air exchange, lung tissue is perpetually exposed to a significant quantity of foreign pathogens. Consequently, lung has developed a refined and intricate immune system. Beyond their physical and chemical barrier roles, lung epithelial cells can contribute to immune defence through the expression of Toll-like receptors (TLRs) and other pattern recognition receptors, along with the secretion of cytokines. Emerging evidence demonstrates that lung epithelial cells can generate and secrete immunoglobulins (Igs), including IgM, IgA, or IgG, thus performing antibody function. Moreover, malignantly transformed lung epithelial cells have been discovered to produce high levels of Ig, predominantly IgG, which do not fulfill the role of antibodies, but instead carries out tumour-promoting activity. Structural analysis has indicated that the biological activity of IgG produced by lung cancer cells differs from that of Igs produced by normal lung epithelial cells due to the unique glycosylation modification. Specifically, the sialylated IgG (SIA-IgG), characterised by a non-traditional N-glycosylation modification at the Asn162 site of Igγ CH1, is highly expressed in tumour stem cells. It has been demonstrated that SIA-IgG relies on this unique sialylation modification to promote tumorigenesis, metastasis, and immune evasion. Current results have proven that the Ig produced by lung epithelial cells has multifaceted biological activities, including immune defence functions under physiological conditions, while acquiring tumour-promoting activity during malignant transformation. These insights possess potential for the diagnosis and treatment of lung cancer as novel biomarkers and targets.

Clinical and biological heterogeneities in triple-negative breast cancer reveals a non-negligible role of HER2-low

Background

HER2-low could be found in some patients with triple-negative breast cancer (TNBC). However, its potential impacts on clinical features and tumor biological characteristics in TNBC remain unclear.

Methods

We enrolled 251 consecutive TNBC patients retrospectively, including 157 HER2-low (HER2low) and 94 HER2-negtive (HER2neg) patients to investigate the clinical and prognostic features. Then, we performed single-cell RNA sequencing (scRNA-seq) with another seven TNBC samples (HER2negvs. HER2low, 4 vs. 3) prospectively to further explore the differences of tumor biological properties between the two TNBC phenotypes. The underlying molecular distinctions were also explored and then verified in the additional TNBC samples.

Results

Compared with HER2neg TNBC, HER2low TNBC patients exhibited malignant clinical features with larger tumor size (P = 0.04), more lymph nodes involvement (P = 0.02), higher histological grade of lesions (P < 0.001), higher Ki67 status (P < 0.01), and a worse prognosis (P < 0.001; HR [CI 95%] = 3.44 [2.10–5.62]). Cox proportional hazards analysis showed that neoadjuvant systemic therapy, lymph nodes involvement and Ki67 levels were prognostic factors in HER2low TNBC but not in HER2neg TNBC patients. ScRNA-seq revealed that HER2low TNBC which showed more metabolically active and aggressive hallmarks, while HER2neg TNBC exhibited signatures more involved in immune activities with higher expressions of immunoglobulin-related genes (IGHG1, IGHG4, IGKC, IGLC2); this was further confirmed by immunofluorescence in clinical TNBC samples. Furthermore, HER2low and HER2neg TNBC exhibited distinct tumor evolutionary characteristics. Moreover, HER2neg TNBC revealed a potentially more active immune microenvironment than HER2low TNBC, as evidenced by positively active regulation of macrophage polarization, abundant CD8+ effector T cells, enriched diversity of T-cell receptors and higher levels of immunotherapy-targeted markers, which contributed to achieve immunotherapeutic response.

Conclusions

This study suggests that HER2low TNBC patients harbor more malignant clinical behavior and aggressive tumor biological properties than the HER2neg phenotype. The heterogeneity of HER2 may be a non-negligible factor in the clinical management of TNBC patients. Our data provide new insights into the development of a more refined classification and tailored therapeutic strategies for TNBC patients.

Radioiodination, purification, and evaluation of antihuman tumor-derived immunoglobulin G light chain monoclonal antibody in tumor-bearing nude mice

We report the synthesis and biological evaluation of ¹³¹ I-labeled antihuman tumor-derived immunoglobulin G (IgG) light chain monoclonal antibody (4E9) ([¹³¹ I]I-4E9) as a promising probe for tumor imaging. [¹³¹ I]I-4E9 was synthesized in radiochemical yield of 89.9 ± 4.7% with radiochemical purity of more than 99%. [¹³¹ I]I-4E9 showed high stability in normal saline and human serum. In cell uptake studies, [¹³¹ I]I-4E9 exhibited favorable binding affinity and high specificity in HeLa MR cells. In biodistribution studies, [¹³¹ I]I-4E9 showed high tumor uptake, high tumor/non-tumor ratios, and specific binding in BALB/c nu/nu mice bearing human HeLa MR xenografts. Single-photon emission computerized tomography (SPECT) imaging of [¹³¹ I]I-4E9 in the HeLa MR xenograft model demonstrated clear visualization of tumor after 48 h and confirmed specific binding in tumor. These findings suggest that [¹³¹ I]I-4E9 possesses favorable biological characteristics and warrants further investigation as a prospective probe for imaging and treatment of cancers.

B Cells in Breast Cancer Pathology

B cells have recently become a focus in breast cancer pathology due to their influence on tumour regression, prognosis, and response to treatment, besides their contribution to antigen presentation, immunoglobulin production, and regulation of adaptive responses. As our understanding of diverse B cell subsets in eliciting both pro- and anti-inflammatory responses in breast cancer patients increases, it has become pertinent to address the molecular and clinical relevance of these immune cell populations within the tumour microenvironment (TME). At the primary tumour site, B cells are either found spatially dispersed or aggregated in so-called tertiary lymphoid structures (TLS). In axillary lymph nodes (LNs), B cell populations, amongst a plethora of activities, undergo germinal centre reactions to ensure humoral immunity. With the recent approval for the addition of immunotherapeutic drugs as a treatment option in the early and metastatic settings for triple-negative breast cancer (TNBC) patients, B cell populations or TLS may resemble valuable biomarkers for immunotherapy responses in certain breast cancer subgroups. New technologies such as spatially defined sequencing techniques, multiplex imaging, and digital technologies have further deciphered the diversity of B cells and the morphological structures in which they appear in the tumour and LNs. Thus, in this review, we comprehensively summarise the current knowledge of B cells in breast cancer. In addition, we provide a user-friendly single-cell RNA-sequencing platform, called "B singLe cEll rna-Seq browSer" (BLESS) platform, with a focus on the B cells in breast cancer patients to interrogate the latest publicly available single-cell RNA-sequencing data collected from diverse breast cancer studies. Finally, we explore their clinical relevance as biomarkers or molecular targets for future interventions.

Does TLS Exist in Canine Mammary Gland Tumours? Preliminary Results in Simple Carcinomas

Neoplastic progression is influenced by the expression of tumour antigens that activate an anti-tumour immune response. Human medical studies show that this body defence is carried out in secondary lymphoid organs (SLOs) but also directly in the tumour through organized cellular aggregates that are called tertiary lymphoid structures (TLSs). However, their occurrence has different meanings in different tumour types. For example, the presence of TLSs in breast cancer is associated with the most aggressive subtypes. This paper aimed to study TLSs in canine mammary simple carcinomas. A morphological assessment of the inflammatory infiltrate was performed on H&E sections of fifty cases. Immunohistochemistry was then carried out to typify the inflammatory cells in the tumour microenvironment. Results showed that, sometimes, inflammatory infiltrates were organized in follicles close to high-grade carcinomas, simulating a lymphoid organization, as in breast cancer. Therefore, we can assume that even in canine mammary tumours, TLSs exist and they are entities to consider due to their presence in the most aggressive histotypes or tumours with a high degree of malignancy.

Relationship between Prognosis, Immune Infiltration Level, and Differential Expression of PARVG Gene in Uterine Corpus Endometrial Carcinoma

Endometrial cancer (UCEC) is very common in gynecological diseases and ranks second in the death cause of gynecological cancer in developed countries. The connection between the overall survival of UCEC patients and immune invasion of the tumor microenvironment is positive. The PARVG gene has not been given notice in cancer, and its mechanism is unknown. The research utilized TCGA data to test the function of PARVG in UCEC. The manifestation of PARVG in UCEC was studied by GEPIA. By assessing the survival module, the authors learned the impact of PARVG on the survival of people with UCEC and then obtained UCEC information from TCGA. This study uses logistic regression to prove the possible relationship between PARVG expression and clinical information. From the research of Cox regression, clinicopathological characteristics of people with TCGA were connected with overall survival. Furthermore, the “correlation” module of GEPIA and CIBERSORT was used to study the association between cancer immune invasion and PARVG. Using univariate logistic regression analysis with PARVG expression as a categorical variable (median expression value of 2.5), the result suggested that raised PARVG expression was considerably connected with tumor status, pathological stage, and lymph nodes. Multiple factor studies have shown that upregulation of PARVG, distant metastasis, and negative pathological stage are absolute elements of excellent prognosis. In addition, CIBERSORT analysis was utilized to determine that raised PARVG expression has a positive connection with immune infiltration by T cells, mast cells, neutrophils, and B cells. This is recognized in GEPIA's “correlation” module. The above outcomes show us that the raised expression of PARVG is associated with a good prognosis and it raises the proportion of immune cells (such as T cells, mast cells, neutrophils, and B cells) in UCEC. These outcomes tell us that PARVG can be utilized as a possible biomarker to evaluate UCEC's immune infiltration levels and prognosis.

SIA-IgG confers poor prognosis and represents a novel therapeutic target in breast cancer

The incidence rate of breast cancer is the highest in the world, and major problem in the clinical treatment is the therapy resistance of breast cancer stem cells (CSCs). Thus, new therapeutic approaches targeting breast CSCs are needed. Our previous study demonstrated cancer-derived sialylated IgG (SIA-IgG) is highly expressed in cancer cells with stem/progenitor features. Furthermore, a high frequency of SIA-IgG in breast cancer tissue predicted metastasis and correlated with poor prognosis factors, and depletion of IgG in breast cancer leads to lower malignancy of cancer cells, suggesting SIA-IgG could be a potential therapeutic target in breast cancer. In this study, we first investigated the relationship of SIA-IgG expression with the clinicopathological characteristics and clinical prognosis of breast carcinoma patients, and the data confirmed that the expression of SIA-IgG confers poor prognosis in breast cancer. Successively, by using a monoclonal antibody specifically against SIA-IgG, we targeted SIA-IgG on the surface of MDA-MB-231 cells and detected their functional changes, and the results suggested SIA-IgG to be a promising antibody therapeutic target in breast cancer. In addition, we explored the mechanism of action at the molecular level of SIA-IgG on breast cancer cell, the findings suggest that SIA-IgG promotes proliferation, metastasis, and invasion of breast cancer cells through the Wnt/β-catenin signaling pathway. Developing therapeutic antibody needs effective therapeutic target, and the antibody should better be a monoclonal antibody with high affinity and high specificity. This study provides a potential prognostic marker and a novel therapeutic target for breast cancer.

A Novel IGLC2 Gene Linked With Prognosis of Triple-Negative Breast Cancer

BACKGROUND

Immunoglobulin-related genes are associated with the favorable prognosis of triple-negative breast cancer (TNBC) patients. We aimed to analyze the function and prognostic value of immunoglobulin lambda constant 2 (IGLC2) in TNBC patients.

METHODS

We knocked down the gene expression of IGLC2 (IGLC2-KD) in MDA-MB-231 cells to evaluate the proliferation, migration, and invasion of tumors via 3-(4,5-Dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, wound healing, and transwell cell migration assay respectively. Relapse-free survival (RFS) and distant metastasis-free survival (DMFS) analyses were conducted using the KM plotter online tool. The GSE76275 data set was used to analyze the association of IGLC2 and clinical characteristics. A pathway enrichment analysis was conducted using the next-generation sequencing data of wild-type and IGLC2-KD MDA-MB-231 cells.

RESULTS

The low gene expression of IGLC2 was related to unfavorable RFS, DMFS. The high expression of IGLC2 was exhibited in the basal-like immune-activated (BLIA) TNBC molecular subtype, which was immune-activated and showed excellent response to immune therapy. IGLC2 was positively correlated with programmed death-ligand 1 (PD-L1) as shown by Spearman correlation (r = 0.25, p < 0.0001). IGLC2 had a strong prognostic effect on lymph node-negative TNBC (RFS range: 0.31, q value= 8.2e-05; DMFS = 0.16, q value = 8.2e-05) but had no significance on lymph node-positive ones. The shRNA-mediated silencing of IGLC2 increased the proliferation, migration, and invasion of MDA-MB-231 cells. The results of pathway enrichment analysis showed that IGLC2 is related to the PI3K-Akt signaling pathway, MAPK signaling pathway, and extracellular matrix-receptor interaction. We confirmed that MDA-MB-231 tumor cells expressed IGLC2, subverting the traditional finding of generation by immune cells.

CONCLUSIONS

IGLC2 linked with the proliferation, migration, and invasion of MDA-MB-231 cells. A high expression of IGLC2 was related to favorable prognosis for TNBC patients. IGLC2 may serve as a biomarker for the identification of TNBC patients who can benefit the most from immune checkpoint blockade treatment.

Down-regulation of IGHG1 enhances Protoporphyrin IX accumulation and inhibits hemin biosynthesis in colorectal cancer by suppressing the MEK-FECH axis

Immunoglobulin γ-1 heavy chain constant region (IGHG1) is a functional isoform of immunoglobulins and plays an important role in the cytolytic activity of immune effector cells. Dysregulated IGHG1 was implicated in the occurrence and development of various tumors. Protoporphyrin IX (PpIX) is an endogenous fluorophore and is used in photodynamic therapy, which induces the generation of reactive oxygen species to initiate the death of tumor cells. However, the roles of IGHG1 in the colorectal cancer cell proliferation and PpIX accumulation have not been reported yet. Data from qRT-PCR and western blot analysis showed that IGHG1 was up-regulated in the colorectal cancer cells. Colorectal cancer cells were then transfected with shRNA targeting IGHG1 to down-regulate IGHG1 and conducted with Cell Counting Kit 8 (CCK8) and colony formation assays. Results demonstrated that shRNA-mediated down-regulation of IGHG1 decreased cell viability of colorectal cancer and suppressed cell proliferation. Moreover, PpIX accumulation was promoted and the hemin content was decreased by the silence of IGHG1. Interference of IGHG1 reduced the phosphorylated extracellular signal-regulated kinase (ERK) and ferrochelatase (FECH) expression, resulting in retarded cell proliferation in an MEK-FECH axis-dependent pathway.

Development of Dl1.72, a Novel Anti-DLL1 Antibody with Anti-Tumor Efficacy against Estrogen Receptor-Positive Breast Cancer

Simple Summary

Over 70% of breast cancers (BCs) are estrogen receptor-positive (ER⁺). The development of endocrine therapy has considerably improved patient outcomes. However, there is a clinical need for novel effective therapies against ER⁺ BCs, since many of these do not respond to standard therapy, and more than one-third of responders acquire resistance, experience relapse and metastasize. The Notch ligand Delta-like 1 (DLL1) is a key player in ER⁺ BC development and aggressiveness. Contrary to complete Notch pharmacological inhibitors, antibody-targeting of individual Notch components is expected to have superior therapeutic efficacy and be better tolerated. In this study, we developed and characterized a novel specific anti-DLL1 antibody with efficacy in inhibiting BC cell proliferation, mammosphere formation and angiogenesis, as well as anti-tumor and anti-metastatic efficacy in an ER⁺ BC mouse model without side effects. Thus, our data suggest that this anti-DLL1 antibody is a promising candidate for ER⁺ BC treatment.

Abstract

The Notch-signaling ligand DLL1 has emerged as an important player and promising therapeutic target in breast cancer (BC). DLL1-induced Notch activation promotes tumor cell proliferation, survival, migration, angiogenesis and BC stem cell maintenance. In BC, DLL1 overexpression is associated with poor prognosis, particularly in estrogen receptor-positive (ER⁺) subtypes. Directed therapy in early and advanced BC has dramatically changed the natural course of ER⁺ BC; however, relapse is a major clinical issue, and new therapeutic strategies are needed. Here, we report the development and characterization of a novel monoclonal antibody specific to DLL1. Using phage display technology, we selected an anti-DLL1 antibody fragment, which was converted into a full human IgG1 (Dl1.72). The Dl1.72 antibody exhibited DLL1 specificity and affinity in the low nanomolar range and significantly impaired DLL1-Notch signaling and expression of Notch target genes in ER⁺ BC cells. Functionally, in vitro treatment with Dl1.72 reduced MCF-7 cell proliferation, migration, mammosphere formation and endothelial tube formation. In vivo, Dl1.72 significantly inhibited tumor growth, reducing both tumor cell proliferation and liver metastases in a xenograft mouse model, without apparent toxicity. These findings suggest that anti-DLL1 Dl1.72 could be an attractive agent against ER⁺ BC, warranting further preclinical investigation.

Current insights into the expression and functions of tumor-derived immunoglobulins

Numerous studies have reported expressions of immunoglobulins (Igs) in many human tumor tissues and cells. Tumor-derived Igs have displayed multiple significant functions which are different from classical Igs produced by B lymphocytes and plasma cells. This review will concentrate on major progress in expressions, functions, and mechanisms of tumor-derived Igs, similarities and differences between tumor-derived Igs and B-cell-derived Igs. We also discuss the future research directions of tumor-derived Igs, including their structural characteristics, physicochemical properties, mechanisms for rearrangement and expression regulation, signaling pathways involved, and clinical applications.

Immune Cells and Immunoglobulin Expression in the Mammary Gland Tumors of Dog

Inflammatory cells have a role in tumor progression and have prognostic and therapeutic potential. The immunohistochemical expression for Mast Cell Tryptase, Macrophage Marker, CD79a, IgA, IgM and IgG on 43 cases of canine mammary gland lesions was analyzed. In hyperplasia, a few B cells (BCs) and Tumor-Associated Macrophages (TAMs) were observed, while the number of Tumor-Associated Mast Cells (TAMCs) was the highest. In the peritumoral stroma of malignant lesions, low number of TAMCs and a high number of TAMAs and BCs were present. Immune cells of each type were always lower in the intratumoral than peritumoral stroma. Positivity to CD79a was also detected in the epithelial cells of simple and micropapillay carcinomas. Immunoglobulin reactivity was mainly located in the epithelial cells where an intense positivity to IgA and IgG and a weak positivity for IgM were detectable. On the basis of our preliminary results and literature data, we suggest that such cells and molecules could be directly involved in the biology of canine mammary gland tumors. In breast cancer, stromal inflammatory cells and cancer derived immunoglobulins have been correlated with the progression, malignancy and poor prognosis of the tumor. The results herein reported show that the dog's mammary gland epithelium also expresses immunoglobulins, and they mostly show a direct relationship with the infiltration of macrophages. In addition, this study shows that the infiltration of mast cells, B-cells and macrophages varies depending on the degree of malignancy of neoplasia.

Immunoglobulin Expression in Cancer Cells and Its Critical Roles in Tumorigenesis

Traditionally, immunoglobulin (Ig) was believed to be produced by only B-lineage cells. However, increasing evidence has revealed a high level of Ig expression in cancer cells, and this Ig is named cancer-derived Ig. Further studies have shown that cancer-derived Ig shares identical basic structures with B cell-derived Ig but exhibits several distinct characteristics, including restricted variable region sequences and aberrant glycosylation. In contrast to B cell-derived Ig, which functions as an antibody in the humoral immune response, cancer-derived Ig exerts profound protumorigenic effects via multiple mechanisms, including promoting the malignant behaviors of cancer cells, mediating tumor immune escape, inducing inflammation, and activating the aggregation of platelets. Importantly, cancer-derived Ig shows promising potential for application as a diagnostic and therapeutic target in cancer patients. In this review, we summarize progress in the research area of cancer-derived Ig and discuss the perspectives of applying this novel target for the management of cancer patients.

Cancer-derived IgG involved in cisplatin resistance through PTP-BAS/Src/PDK1/AKT signaling pathway

OBJECTIVES

This study aimed to explore whether knockdown of cancer-derived IgG (CIgG) could enhance cisplatin-induced anti-cancer effects.

MATERIALS AND METHODS

Cancer-derived IgG was knocked down by siRNA or Tet-on shRNA in the absence or presence of cisplatin in WSU-HN6 or CAL27 cells. Cell proliferation, apoptosis, and mobility were evaluated using CCK-8, flow cytometry, and transwell assays, respectively. Molecular events were investigated using real-time PCR and Western blot assays.

RESULTS

Knockdown of CIgG significantly promoted cisplatin-induced apoptosis and inhibition of cell proliferation, migration, and invasion. Cisplatin upregulated CIgG expression and phosphorylation of AKT and PDK1, while knockdown of CIgG downregulated phosphorylation of AKT and PDK1, and blocked cisplatin-induced upregulation of AKT and PDK1 phosphorylation. Moreover, knockdown of CIgG blocked cisplatin-induced upregulation of Src phosphorylation, and knockdown of Src blocked cisplatin-induced upregulation of AKT and PDK1 phosphorylation. Overexpression of Src upregulated AKT and PDK1 phosphorylation. Furthermore, knockdown of CIgG upregulated PTP-BAS mRNA and protein expression, whereas cisplatin downregulated PTP-BAS protein, but not mRNA expression; knockdown of PTP-BAS upregulated phosphorylation of Src, PDK1, AKT, and blocked CIgG knockdown-mediated enhancement of cisplatin-induced inhibition of cell proliferation.

CONCLUSION

Knockdown of CIgG enhanced the anti-cancer effects of cisplatin through PTP-BAS/Src/PDK1/AKT signaling pathway in oral squamous cell carcinoma.

Cancer-derived sialylated IgG promotes tumor immune escape by binding to Siglecs on effector T cells

To date, IgG in the tumor microenvironment (TME) has been considered a product of B cells and serves as an antitumor antibody. However, in this study, using a monoclonal antibody against cancer-derived IgG (Cancer-IgG), we found that cancer cells could secrete IgG into the TME. Furthermore, Cancer-IgG, which carries an abnormal sialic acid modification in the CH1 domain, directly inhibited effector T-cell proliferation and significantly promoted tumor growth by reducing CD4⁺ and CD8⁺ T-cell infiltration into tumor tissues. Mechanistic studies showed that the immunosuppressive effect of sialylated Cancer-IgG is dependent on its sialylation and binding to sialic acid-binding immunoglobulin-type lectins (Siglecs) on effector CD4⁺ and CD8⁺ T cells. Importantly, we show that several Siglecs are overexpressed on effector T cells from cancer patients, but not those from healthy donors. These findings suggest that sialylated Cancer-IgG may be a ligand for Siglecs, which may serve as potential checkpoint proteins and mediate tumor immune evasion.

Six novel immunoglobulin genes as biomarkers for better prognosis in triple-negative breast cancer by gene co-expression network analysis

Gene co-expression network analysis (GCNA) can detect alterations in regulatory activities in case/control comparisons. We propose a framework to detect novel genes and networks for predicting breast cancer recurrence. Thirty-four prognosis candidate genes were selected based on a literature review. Four Gene Expression Omnibus Series (GSE) microarray datasets (n = 920) were used to create gene co-expression networks based on these candidates. We applied the framework to four comparison groups according to node (+/−) and recurrence (+/−). We identified a sub-network containing two candidate genes (LST1 and IGHM) and six novel genes (IGHA1, IGHD, IGHG1, IGHG3, IGLC2, and IGLJ3) related to B cell-specific immunoglobulin. These novel genes were correlated with recurrence under the control of node status and were found to function as tumor suppressors; higher mRNA expression indicated a lower risk of recurrence (hazard ratio, HR = 0.87, p = 0.001). We created an immune index score by performing principle component analysis and divided the genes into low and high groups. This discrete index significantly predicted relapse-free survival (RFS) (high: HR = 0.77, p = 0.019; low: control). Public tool KM Plotter and TCGA-BRCA gene expression data were used to validate. We confirmed these genes are correlated with RFS and distal metastasis-free survival (DMFS) in triple-negative breast cancer (TNBC) and general breast cancer.

Cancer IgG, a potential prognostic marker, promotes colorectal cancer progression

Objective

Currently, no satisfactory targets for colorectal cancer or markers for immunotherapy and diagnosis and prognosis are available. Immunoglobulin G (IgG) is widely expressed in many cancers, and it promotes cancer progression. This study explored the role of cancer-derived IgG (CIgG) in colorectal cancer.

Methods

First, using a monoclonal antibody to CIgG, we examined the expression levels of CIgG in colorectal cancer cell lines by western blot and immunofluorescence analyses and in tissue specimens by immunohistochemistry. Second, the variable region gene was amplified by nested polymerase chain reaction (PCR), and PCR products were sequenced and analyzed. Third, we investigated the effect of CIgG on colorectal cancer cells by cell proliferation, wound healing, migration and invasion assays, and colony formation assay. Fourth, we performed in vivo tumorigenicity experiments to explore the effect of CIgG on tumorigenicity. Finally, we used RNA-seq analysis and co-immunoprecipitation experiments to further clarify possible mechanisms of CIgG.

Results

We found that CIgG is widely expressed in colorectal cancer cells, and the overexpression of CIgG indicates significantly poor colorectal cancer prognosis. Furthermore, CIgG knockdown significantly inhibits the proliferation, migration and invasion ability of cells, and tumor growth in vivo. RNA-seq analysis indicated that CIgG knockdown results primarily in changes in expression of apical junction and epithelial-mesenchymal transition-related genes. CIgG may be involved in colorectal cancer invasion and metastasis through interacting with E-cadherin.

Conclusions

CIgG is a potential human oncogene in colorectal cancer and that it has potential for application as a novel target in targeted therapy and a marker for prognostic evaluation.

Aberrant high expression of immunoglobulin G in epithelial stem/progenitor-like cells contributes to tumor initiation and metastasis

High expression of immunoglobulin G (IgG) in many non-B cell malignancies and its non-conventional roles in promoting proliferation and survival of cancer cells have been demonstrated. However, the precise function of non-B IgG remains incompletely understood. Here we define the antigen specificity of RP215, a monoclonal antibody that specifically recognizes the IgG in cancer cells. Using RP215, our study shows that IgG is overexpressed in cancer cells of epithelial lineage, especially cells with cancer stem/progenitor cell-like features. The RP215-recognized IgG is primarily localized on the cell surface, particularly lamellipodia-like structures. Cells with high IgG display higher migration, increased invasiveness and metastasis, and enhanced self-renewal and tumorgenecity ability in vitro and in vivo. Importantly, depletion of IgG in breast cancer leads to reduced adhesion, invasion and self-renewal and increased apoptosis of cancer cells. We conclude that high expression of IgG is a novel biomarker of tumor progression, metastasis and cancer stem cell maintenance and demonstrate the potential therapeutic benefits of RP215-recognized IgG targeted strategy.

Pancreatic Expression of Immunoglobulin G in Human Pancreatic Cancer and Associated Diabetes

OBJECTIVES

The prognosis of pancreatic cancer (PC) is poor and the pathogenesis of PC-associated diabetes is unknown. We investigated the possible expression of immunoglobulin G (IgG) in human pancreatic carcinomas and adjacent pancreatic islets to gain a better understanding of these diseases.

METHODS

We employed immunohistochemistry, Western Blot, real-time polymerase chain reaction, and in situ hybridization to examine IgG expression in PC tissues and adjacent islets with and without cancer-associated diabetes. The IgG mRNA and IgG synthesizing-related enzymes were examined in PC cell lines. The IgG expression and secretion were downregulated with specific small interfering RNA and antibody to IgG followed by flow cytometry to assess its effect on apoptosis of cultured PC cells.

RESULTS

The expression of IgG was detected in pancreatic carcinoma and adjacent islets. Small interfering RNA and antibody treatments induced apoptosis in PC cell lines. In the carcinoma tissue, the levels of IgG expression varied depending on the stages of the cancers with more malignant cancers expressing more IgG (P < 0.05). The IgG levels in cancer cells were also increased when the patients had diabetes or hyperglycemia (P < 0.05). In addition, the extent of IgG expression in the seemingly normal islet cells adjacent to the tumor varied in relation to the grade of cancer differentiation and distance to the cancer nests.

CONCLUSIONS

(1) Immunoglobulin G was locally produced by PC cells and adjacent islet cells. (2) Immunoglobulin G may promote tumor growth by inhibiting cancer cell apoptosis. (3) Locally produced IgG might play a role in PC-associated diabetes.

Immunoglobulin free light chains are biomarkers of poor prognosis in basal-like breast cancer and are potential targets in tumor-associated inflammation

Inflammation is an important component of various cancers and its inflammatory cells and mediators have been shown to have prognostic potential. Tumor-infiltrating mast cells can promote tumor growth and angiogenesis, but the mechanism of mast cell activation is unclear. In earlier studies, we demonstrated that immunoglobulin free light chains (FLC) can trigger mast cells in an antigen-specific manner. Increased expression of FLC was observed within stroma of various human cancers including those of breast, colon, lung, pancreas, kidney and skin, and FLC expression co-localized with areas of mast cell infiltration. In a large cohort of breast cancer patients, FLC expression was shown associated with basal-like cancers with an aggressive phenotype. Moreover, lambda FLC was found expressed in areas of inflammatory infiltration and its expression was significantly associated with poor clinical outcome. Functional importance of FLCs was shown in a murine B16F10 melanoma model, where inhibition of FLC-mediated mast cell activation strongly reduced tumor growth. Collectively, this study identifies FLCs as a ligand in the pro-tumorigenic activation of mast cells. Blocking this pathway may open new avenues for the inhibition of tumor growth, while immunohistochemical staining of FLC may be helpful in the diagnosis and prognosis of cancer.