Immunoglobulin G expression in carcinomas and cancer cell lines

Potential shared neoantigens from pan-cancer transcript isoforms

Isoform switching in cancer is a prevalent phenomenon with significant implications for immunotherapy, as actionable neoantigens derived from these cancer-specific events would be applicable to broad categories of patients, reducing the necessity for personalized treatments. By integrating five large-scale transcriptomic datasets comprising over 19,500 samples across 29 cancer and 54 normal tissue types, we identified cancer-associated isoform switching events common to multiple cancer types, several of which involve genes with established mechanistic roles in oncogenesis. The presence of neoantigen-containing peptides derived from these transcripts was confirmed in broad cancer and normal tissue proteome datasets and the binding affinity of predicted neoantigens to the human leukocyte antigen (HLA) complex via molecular dynamics simulations. The study presents strong evidence that isoform switching in cancer is a significant source of actionable neoantigens that have the capability to trigger an immune response. These findings suggest that isoform switching events could potentially be leveraged for broad immunotherapeutic strategies across various cancer types.

Sialylated IgG-activated integrin β4-Src-Erk axis stabilizes c-Myc in a p300 lysine acetyltransferase-dependent manner to promote colorectal cancer liver metastasis

BACKGROUND

Liver metastasis is a leading cause of colorectal cancer mortality. Therefore, the underlying mechanism and potential therapeutic target of colorectal cancer liver metastasis urge to be found. Mounting evidence indicates that cancer-derived sialylated IgG promotes tumor formation and progression. However, the role of sialylated IgG in colorectal cancer liver metastasis remains undefined.

MATERIALS AND METHODS

Analysis of sialylated IgG in paired tumor tissues and adjacent normal tissues from 65 colorectal cancer patients was performed using immunohistochemical staining. Functional assays of sialylated IgG were explored in vitro and in vivo. The downstream target of sialylated IgG was investigated by performing gene-set enrichment analysis, ubiquitination assay, cycloheximide chase assay, acetylation assay and co-immunoprecipitation.

RESULTS

Here, our investigation reveals that sialylated IgG is significantly upregulated in colorectal cancer and that the increase of IgG is positively associated with liver metastasis and poor overall survival in colorectal cancer patients. Sialylated IgG promotes colorectal cancer cell migration, invasion and liver metastasis. Notably, anti-sialylated IgG antibody effectively blocks colorectal cancer liver metastasis in mouse models. Mechanistically, sialylated IgG upregulates c-Myc protein level by decreasing c-Myc ubiquitination. Moreover, we find that p300/CBP can stabilize c-Myc by reducing c-Myc ubiquitination. Overexpression of p300/CBP protects c-Myc protein level from sialylated IgG-knockdown in a lysine acetyltransferase activity-dependent manner. Furthermore, sialylated IgG upregulates p300 protein level through integrin β4-FAK-Src-Erk signaling.

CONCLUSION

Collectively, these results indicate that a novel sialylated IgG-integrin β4-FAK-Src-Erk-p300-c-Myc signaling pathway promotes colorectal cancer liver metastasis, thus providing potential therapeutic targets for colorectal cancer liver metastasis.

CXCL1/IGHG1 signaling enhances crosstalk between tumor cells and tumor-associated macrophages to promote MC-LR-induced colorectal cancer progression

Microcystin-leucine arginine (MC-LR) is a common cyantotoxin produced by hazardous cyanobacterial blooms, and eutrophication is increasing the contamination level of MC-LR in drinking water supplies and aquatic foods. MC-LR has been linked to colorectal cancer (CRC) progression associated with tumor microenvironment, however, the underlying mechanism is not clearly understood. In present study, by using GEO, KEGG, GESA and ImmPort database, MC-LR related differentially expressed genes (DEGs) and pathway- and gene set-enrichment analysis were performed. Of the three identified DEGs (CXCL1, GUCA2A and GDF15), CXCL1 was shown a positive association with tumor infiltration, and was validated to have a dominantly higher upregulation in MC-LR-treated tumor-associated macrophages (TAMs) rather than in MC-LR-treated CRC cells. Both CRC cell/macrophage co-culture and xenograft mouse models indicated that MC-LR stimulated TAMs to secrete CXCL1 resulting in promoted proliferation, migration, and invasion capability of CRC cells. Furtherly, IP-MS assay found that interaction between TAMs-derived CXCL1 and CRC cell-derived IGHG1 may enhance CRC cell proliferation and migration after MC-LR treatment, and this effect can be attenuated by silencing IGHG1 in CRC cell. In addition, molecular docking analysis, co-immunoprecipitation and immunofluorescence further proved the interactions between CXCL1 and IGHG1. In conclusion, CXCL1 secreted by TAMs can trigger IGHG1 expression in CRC cells, which provides a new clue in elucidating the mechanism of MC-LR-mediated CRC progression.

The Role of Neutrophil Extracellular Traps in the Outcome of Malignant Epitheliomas: Significance of CA215 Involvement

Neutrophil extracellular traps (NETs) were originally discovered as a part of the innate immune response of the host to bacteria. They form a web-like structure that can immobilize microorganisms or exhibit direct antimicrobial properties, such as releasing reactive oxygen species (ROS). NETs are established when neutrophils undergo a sort of cellular death following exposure to ROS, chemokines, cytokines, or other soluble factors. This process results in the release of the neutrophil's DNA in a web-like form, which is decorated with citrullinated histones (H3/H4-cit), neutrophil elastase (NE), and myeloperoxidase (MPO). Emerging studies have put into perspective that NETs play an important role in oncology as they were shown to influence tumor growth, malignant initiation, and proliferation, mediate the transition from endothelial to mesenchymal tissue, stimulate angiogenesis or metastasis, and can even help cancer cells evade the immune response. The role of NETs in cancer therapy resides in their ability to form and act as a mechanical barrier that will provide the primary tumor with a reduced response to irradiation or pharmaceutical penetration. Subsequently, cancer cells are shown to internalize NETs and use them as a strong antioxidant when pharmaceutical treatment is administered. In this review, we explored the role of NETs as part of the tumor microenvironment (TME), in the context of malignant epitheliomas, which are capable of an autonomous production of CA215, a subvariant of IgG, and part of the carcinoembryonic antigen (CEA) superfamily. Studies have shown that CA215 has a functional Fc subdivision able to activate the Fc-gamma-RS receptor on the surface of neutrophils. This activation may afterward stimulate the production of NETs, thus indicating CA215 as a potential factor in cancer therapy surveillance.

Non B Cell-Derived Immunoglobulins in Intestinal Tract

Intestinal epithelium constitutes a barrier to the unrestricted movement of pathogens, and other detrimental substances from the external world (gut lumen) into the interstitial environment. Intestinal epithelial cells obstruct harmful substances passing through the epithelium as a physical and chemical barrier; Moreover, the epithelial cells can express Toll-like receptors (TLRs) and cytokines to exert innate immune function. In addition, high levels of immunoglobulin A (IgA) and other antibodies exist in the intestinal mucosa, maintaining intestinal immune homeostasis in conjunction with intestinal probiotics. Traditionally, these antibodies have been deemed to be secreted by submucosal plasma cells. Nonetheless, in recent years, it has been demonstrated that intestinal epithelial cells produce a substantial amount of Igs, especially IgA or free Ig light chains, which are involved in intestinal immune homeostasis and the survival of normal epithelial cells. Furthermore, mounting evidence affirms that many human carcinoma cells, including colorectal cancer (CRC), can overexpress Igs, particularly IgG. Cancer-derived Igs exhibit a unique V(D)J rearrangement pattern distinct from B cell-derived Ig; moreover, this cancer cell-derived IgG also has a unique sialic acid modification on the 162 site of CH1 domain (SIA-IgG). The SIA-IgG plays a crucial role in promoting cancer initiation, progression, metastasis, and tumour immune escape. Simultaneously, CRC cells can also express free Ig light chains, which promote colitis, colitis-associated colon carcinogenesis, and CRC progression. Therefore, Igs expressed by CRC cells could be a potential target for diagnosing and preventing the transformation of inflammation into cancer, as well as treating CRC.

Genetic Characteristics of Non B Cell-Derived Immunoglobulin Genes

It is widely acknowledged that immunoglobulins (Igs) are produced solely by B-lineage cells. The Ig gene is created by the rearrangement of a group of gene segments [variable (V), diversity (D), and joining (J) segments rearrangement, or V(D)J recombination], which results in the vast diversity of B cell-derived Ig responsible for recognising various antigens. Ig subsequently undergoes somatic hypermutation (SHM) and class switch recombination (CSR) after exposure to antigens, thus converting the low-affinity IgM to IgG, IgA, or IgE antibodies. IgM and IgD are primarily expressed in naïve B cells that have not been exposed to antigens, they do not undergo somatic hypermutation; hence, their variable region sequences remain the same as those in the germline. In contrast, IgG, IgA, and IgE are expressed in antigen-stimulated memory B cells or plasma cells, and thus, they often possess high-frequency mutations in their variable region sequences. Since the discovery that Ig can be produced by non-B cells, Qiu's group has investigated and compared the genetic characteristics of B cell-derived Ig and non-B cell-derived Ig. These findings demonstrated that non-B cell-derived Ig shares certain similarities with B cell-derived Ig in that the sequence of its constant region is identical to that of B cell-derived Ig, and its variable region is also strictly dependent on the rearrangement of V, D, and J gene segments. Moreover, akin to B cell-derived Ig, the V regions of IgM and IgD are rarely mutated, while IgG, IgA, and IgE produced by cancer cells are frequently mutated. However, the non-B cell-derived Ig V region sequence displays unique characteristics. (1) Unlike the vast diversity of B cell-derived Igs, non-B cell-derived Igs exhibit restricted diversity; cells from the same lineage always select the same V(D)J recombination patterns; (2) Both mRNA and proteins of RAG1/RAG2 recombinase have been detected in Ig positive cancer cell lines and normal tissues. But Ig recombination could also be found in RAG1-/- and RAG2-/- mice, suggesting that they are not necessary for the rearrangement of non-B cell-derived Igs. These features of non-B cell-derived Igs suggest a potentially undiscovered mechanism of V(D)J recombination, ligation, and SHM in non-B cells, which necessitates further investigation with advanced technology in molecular biology.

The Structure Characteristics and Function of Non B Cell-Derived Immunoglobulin

According to classical immunology theory, immunoglobulin (Ig) is exclusively produced by differentiated B lymphocytes, which exhibit a typical tetrapeptide chain structure and are predominantly present on the surface of B cells and in bodily fluids. B-Ig is one of the critical effector molecules for humoral immune responses specifically recognising antigens and eliminating them. However, mounting evidence has demonstrated that Ig is widely expressed in non B lineage cells, especially malignant ones (referred to as non B-Ig). Interestingly, non B-Ig mainly resides in the cytoplasm and secretion, but to some extent on the cell surface. Furthermore non B-Ig not only displays a tetrapeptide chain structure but also shows free heavy chains and free light chains (FLCs). Additionally, Ig derived from non B cancer cell typically displays unique glycosylation modifications. Functionally, non B-Ig demonstrated diversity and versatility, showing antibody activity and cellular biological activity, such as promoting cell proliferation and survival, and it is implicated in cancer progression and some immune-related diseases, such as renal diseases.

Functions and Clinical Relevance of Liver-Derived Immunoglobulins

Liver is the largest internal organ of the body with vital functions. In addition to its endocrine and exocrine activities, liver also plays a pivotal role in the immune system, including haematopoietic functions. Liver parenchymal cells, which are epithelial cells, have been found to possess innate immune functions by expressing pattern-recognition receptors (PRRs), producing complement components, and secreting cytokines. Intriguingly, in recent years, it has been discovered that liver epithelial cells also produce immunoglobulins (Igs), which have long been thought to be produced exclusively by B cells. Notably, even liver epithelial cells from B lymphocyte-deficient mice, including SCID mice and μMT mice, could also produce Igs. Compelling evidence has revealed both the physiological and pathological functions of liver-derived Igs. For instance, liver epithelial cells-derived IgM can serve as a source of natural and specific antibodies that contribute to innate immune responses, while liver-produced IgG can act as a growth factor to promote cell proliferation and survival in normal hepatocytes and hepatocarcinoma. Similar to that in B cells, the toll-like receptor 9 (TLR9)-MyD88 signaling pathway is also actively involved in promoting liver epithelial cells to secrete IgM. Liver-derived Igs could potentially serve as biomarkers, prognostic indicators, and therapeutic targets in the clinical setting, particularly for liver cancers and liver injury. Nevertheless, despite significant advances, much remains unknown about the mechanisms governing Ig transcription in liver cells, as well as the detailed functions of liver-derived Igs and their involvement in diseases and adaptive immunity. Further studies are still needed to reveal these underlying, undefined issues related to the role of liver-derived Igs in both immunity and diseases.

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.

Non B Cell-Derived Immunoglobulin, A Brighter Horizon for the Future

The canonical theory of immunology stating that "Immunoglobulin (Ig) is produced by B lymphocytes and exerts antibody activity" has been established since the 1970s. However, the discovery of non B cell-derived Igs (non B-Igs), which can exert multiple biological activities in addition to their antibody activities, necessitates a reevaluation of the classic concept of Ig. This has been documented with a number of characteristics related to their structure, modification, genetic regulation as well as the functions associated with clinical conditions, particularly multiple cancers. The discovery of non B-Ig provides us with a new perspective to better understand not only basic immunology, but also various Ig-related clinical manifestations including autoimmune diseases, chronic inflammation, and anaphylaxis. Notably, non B-Ig can directly promote the occurrence of malignant tumours.

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.

Cancer-Derived Immunoglobulin G and Pancreatic Cancer

Immunoglobulin (Ig) is traditionally believed to be produced solely by B cells. Nonetheless, mounting evidence has demonstrated that various types of Igs are extensively expressed in many cell types. Among them, IgG is found to be highly expressed in cancer cells and is thus labeled as cancer-derived IgG. Cancer-derived IgG shares identical fundamental structures with B cell-derived IgG, but displays several unique characteristics, including restricted variable region sequences and unique glycosylation modifications for those expressed by epithelial cancers. Cancer-derived IgG plays multiple crucial roles in carcinogenesis, including facilitating cancer invasion and metastasis, enhancing cancer stemness, contributing to chemoresistance, and remodeling the tumour microenvironment. Recent studies have discovered that cancer-derived sialylated IgG (SIA-IgG) is extensively expressed in pancreatic cancer cells and is predominantly located in the cytoplasm and on the cell membrane. Cancer-derived IgG expressed by pancreatic cancer presents a restrictive variable region sequence and contains a unique sialylation site of the Fab region. Functionally, cancer-derived IgG participates in pancreatic cancer progression via different mechanisms, such as promoting proliferation, facilitating migration and invasion, resisting apoptosis, inducing inflammation, and modulating the tumour microenvironment. SIA-IgG has shown potential as a clinical biomarker. The expression of SIA-IgG is associated with poor tumour differentiation, metastasis, and chemoresistance in pancreatic cancer. High expression of SIA-IgG can serve as an independent prognostic factor for pancreatic cancer. Additionally, SIA-IgG expression elevated with malignant progression for the precursor lesions of pancreatic cancer. These findings present a prospect of applying cancer-derived IgG as a novel diagnostic and therapeutic target in the management of pancreatic cancer, and aiding in overcoming the challenge in the treatment of this stubborn malignancy.

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.

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.

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.

Identifying tumour microenvironment-related signature that correlates with prognosis and immunotherapy response in breast cancer

Tumor microenvironment (TME) plays important roles in prognosis and immune evasion. However, the relationship between TME-related genes and clinical prognosis, immune cell infiltration, and immunotherapy response in breast cancer (BRCA) remains unclear. This study described the TME pattern to construct a TME-related prognosis signature, including risk factors PXDNL, LINC02038 and protective factors SLC27A2, KLRB1, IGHV1-12 and IGKV1OR2-108, as an independent prognostic factor for BRCA. We found that the prognosis signature was negatively correlated with the survival time of BRCA patients, infiltration of immune cells and the expression of immune checkpoints, while positively correlated with tumor mutation burden and adverse treatment effects of immunotherapy. Upregulation of PXDNL and LINC02038 and downregulation of SLC27A2, KLRB1, IGHV1-12 and IGKV1OR2-108 in high-risk score group synergistically contribute to immunosuppressive microenvironment which characterized by immunosuppressive neutrophils, impaired cytotoxic T lymphocytes migration and natural killer cell cytotoxicity. In summary, we identified a TME-related prognostic signature in BRCA, which was connected with immune cell infiltration, immune checkpoints, immunotherapy response and could be developed for immunotherapy targets.

Genetic Influences in Cancer-Associated Myositis

Idiopathic inflammatory myopathies (IIMs) comprise a heterogeneous group of rare immune-mediated disorders that primarily affect muscles but also lead to dysfunction in other organs. Five different clinical subphenotypes of IIM have been distinguished: dermatomyositis, polymyositis, inclusion body myositis, antisynthetase syndrome, and immune-mediated necrotizing myopathy. Excess mortality and morbidity associated with IIM are largely attributed to comorbidities, particularly cancer. The risk of malignancy is not equally distributed among IIM groups and is particularly high among patients with dermatomyositis. The cancer risk peaks around 3 years on either side of the IIM diagnosis and remains elevated even 10 years after the onset of the disease. Lung, colorectal, and ovarian neoplasms typically arise before the onset of IIM, whereas melanoma, cervical, oropharyngeal, and nonmelanoma skin cancers usually develop after IIM diagnosis. Given the close temporal proximity between IIM diagnosis and the emergence of malignancy, it has been proposed that IIM could be a consequence rather than a cause of cancer, a process known as a paramalignant phenomenon. Thus, a separate group of IIMs related to paramalignant phenomenon has been distinguished, known as cancer-associated myositis (CAM). Although the relationship between IIM and cancer is widely recognized, the pathophysiology of CAM remains elusive. Given that genetic factors play a role in the development of IIM, dissection of the molecular mechanisms shared between IIM and cancer presents an opportunity to examine the role of autoimmunity in cancer development and progression. In this review, the evidence supporting the contribution of genetics to CAM will be discussed.

Glycoproteomic analysis reveals the effects of bisecting GlcNAc in intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is the second major subtype of primary liver cancer and has caused more and more attention with increasing incidence and mortality worldwide. Our previous study found that bisecting N-glycans are commonly increased in ICC, while the effects and potential functions of bisecting GlcNAc in ICC are still largely unclear. In this study, we further confirmed that the structures of bisecting GlcNAc were significantly up-regulated in ICC compared with paracancer tissues by glycoproteomic data and lectin histochemistry. The expression of its glycosyltransferase MGAT3 was also up-regulated in ICC tissues at both mRNA and protein levels, and expression of MGAT3 is negatively correlated with overall survival explored by bioinformatic analyses and published datasets from 255 patients. Next, the silencing of MGAT3 could inhibit the growth and invasion of ICC cells, and overexpressing of MGAT3 only promoted ICC cell invasion. Further glycoproteomic analysis showed that the commonly glycoproteins modified by bisecting GlcNAc after MGAT3-overexpression in two ICC cell lines were mainly involved in cell movement-related biological processes, such as cell adhesion, integrin-related and ECM-receptor interaction. This study sheds light on the potential effects of bisecting GlcNAc in ICC cells and suggests that MGAT3 might be used as a potential target in the therapy of ICC.

Nonamer dependent RAG cleavage at CpGs can explain mechanism of chromosomal translocations associated to lymphoid cancers

Chromosomal translocations are considered as one of the major causes of lymphoid cancers. RAG complex, which is responsible for V(D)J recombination, can also cleave non-B DNA structures and cryptic RSSs in the genome leading to chromosomal translocations. The mechanism and factors regulating the illegitimate function of RAGs resulting in oncogenesis are largely unknown. Upon in silico analysis of 3760 chromosomal translocations from lymphoid cancer patients, we find that 93% of the translocation breakpoints possess adjacent cryptic nonamers (RAG binding sequences), of which 77% had CpGs in proximity. As a proof of principle, we show that RAGs can efficiently bind to cryptic nonamers present at multiple fragile regions and cleave at adjacent mismatches generated to mimic the deamination of CpGs. ChIP studies reveal that RAGs can indeed recognize these fragile sites on a chromatin context inside the cell. Finally, we show that AID, the cytidine deaminase, plays a significant role during the generation of mismatches at CpGs and reconstitute the process of RAG-dependent generation of DNA breaks both in vitro and inside the cells. Thus, we propose a novel mechanism for generation of chromosomal translocation, where RAGs bind to the cryptic nonamer sequences and direct cleavage at adjacent mismatch generated due to deamination of meCpGs or cytosines.

Identification of the Antigens Recognised by Colorectal Cancer Patients Using Sera from Patients Who Exhibit a Crohn's-like Lymphoid Reaction

A Crohn’s-like lymphoid reaction (CLR) is observed in about 15% of colorectal cancer (CRC) patients and is associated with favourable outcomes. To identify the immune targets recognised by CRC CLR patient sera, we immunoscreened a testes cDNA library with sera from three patients. Immunoscreening of the 18 antigens identified by SEREX with sera from normal donors showed that only the heavy chain of IgG3 (IGHG3) and a novel antigen we named UOB-COL-7, were solely recognised by sera from CRC CLR patients. ELISA showed an elevation in IgG3 levels in patients with CRC (p = 0.01). To extend our studies we analysed the expression of our SEREX-identified antigens using the RNA-sequencing dataset (GSE5206). We found that the transcript levels of multiple IGHG probesets were highly significant (p < 0.001) in their association with clinical features of CRC while above median levels of DAPK1 (p = 0.005) and below median levels of GTF2H5 (p = 0.004) and SH3RF2 (p = 0.02) were associated with improved overall survival. Our findings demonstrate the potential of SEREX-identified CRC CLR antigens to act as biomarkers for CRC and provide a rationale for their further characterization and validation.

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.

Upregulated Expression of Cancer-Derived Immunoglobulin G Is Associated With Progression in Glioma

Objective

Gliomas are the most aggressive intracranial tumors accounting for the vast majority of brain tumors with very poor prognosis and overall survival (OS). Cancer-derived immunoglobulin G (cancer-IgG) has been found to be widely expressed in several malignancies such as breast cancer, colorectal cancer, and lung cancer. Cancer-IgG could promote tumorigenesis and progression. However, its role in glioma has not been revealed yet.

Methods

We mined open databases including the Chinese Glioma Genome Atlas (CGGA), The Cancer Genome Atlas (TCGA), and the Gene Expression Omnibus (GEO) to study the role of IGHG1, which encodes cancer-IgG in glioma. Examination of the differential expression of IGHG1 was carried out in the GEO and TCGA databases. Furthermore, its expression in different molecular subtypes was analyzed. Stratified analysis was performed with clinical features. Subsequently, immune infiltration analysis was conducted using single-sample gene set enrichment analysis (ssGSEA). GSEA was performed to reveal the mechanisms of IGHG1. Lastly, immunohistochemistry was processed to validate our findings.

Results

In this study, we found that the expression of IGHG1 was higher in glioma and molecular subtypes with poor prognosis. The overall survival of patients with a high expression of IGHG1 was worse in the stratified analysis. Immune infiltration analysis indicated that the expression level of IGHG1 was positively correlated with the stromal score, ESTIMATE score, and immune score and negatively correlated with tumor purity. Results from the GSEA and DAVID demonstrated that IGHG1 may function in phagosome, antigen processing and presentation, extracellular matrix structural constituent, antigen binding, and collagen-containing extracellular matrix. Finally, immunohistochemistry assay validated our findings that patients with a high expression of cancer-IgG had poor OS and disease-free survival (DFS).

Conclusion

Cancer-IgG is a promising biomarker of diagnosis and treatment for patients with glioma.

Cancer-Cell-Derived IgG and Its Potential Role in Tumor Development

Human immunoglobulin G (IgG) is the primary component of the human serum antibody fraction, representing about 75% of the immunoglobulins and 10-20% of the total circulating plasma proteins. Generally, IgG sequences are highly conserved, yet the four subclasses, IgG1, IgG2, IgG3, and IgG4, differ in their physiological effector functions by binding to different IgG-Fc receptors (FcγR). Thus, despite a similarity of about 90% on the amino acid level, each subclass possesses a unique manner of antigen binding and immune complex formation. Triggering FcγR-expressing cells results in a wide range of responses, including phagocytosis, antibody-dependent cell-mediated cytotoxicity, and complement activation. Textbook knowledge implies that only B lymphocytes are capable of producing antibodies, which recognize specific antigenic structures derived from pathogens and infected endogenous or tumorigenic cells. Here, we review recent discoveries, including our own observations, about misplaced IgG expression in tumor cells. Various studies described the presence of IgG in tumor cells using immunohistology and established correlations between high antibody levels and promotion of cancer cell proliferation, invasion, and poor clinical prognosis for the respective tumor patients. Furthermore, blocking tumor-cell-derived IgG inhibited tumor cells. Tumor-cell-derived IgG might impede antigen-dependent cellular cytotoxicity by binding antigens while, at the same time, lacking the capacity for complement activation. These findings recommend tumor-cell-derived IgG as a potential therapeutic target. The observed uniqueness of Ig heavy chains expressed by tumor cells, using PCR with V(D)J rearrangement specific primers, suggests that this specific part of IgG may additionally play a role as a potential tumor marker and, thus, also qualify for the neoantigen category.

IGHG1 upregulation promoted gastric cancer malignancy via AKT/GSK-3β/β-Catenin pathway

Background

Despite current advances in gastric cancer treatment, disease metastasis and chemo-resistance remain as major hurdles against better overall prognosis. Previous studies indicated that IGHG1 as well as -Catenin serve as important regulators of tumor cellular malignancy. Therefore, understanding detailed molecular mechanism and identifying druggable target will be of great potentials in future therapeutic development.

Methods

Surgical tissues and gastric cancer cell lines were retrieved to evaluate IGHG1 expression for patients with or without lymph node/distal organ metastasis. Functional assays including CCK8 assay, Edu assay, sphere formation assay and transwell assay, wound healing assay, etc. were subsequently performed to evaluate the impact of IGHG1/-catenin axis on tumor cell proliferation, migration and chemo-resistance.

Results

Gastric cancer tissues and tumor cell lines demonstrated significantly higher level of IGHG1. Functional study further demonstrated that IGHG1 promoted proliferative and migration as well as chemo-resistance of gastric cancer tumor cells. Further experiments indicated that IGHG1 activated AKT/GSK-3/-Catenin axis, which played crucial role in regulation of proliferative and chemo-resistance of gastric cancer cells.

Conclusion

This study provided novel evidences that IGHG1 acted as oncogene by promotion of gastric cancer cellular proliferation, migration and chemo-resistance. Our research further suggested that IGHG1/AKT/GSK-3β/β-Catenin axis acted as novel pathway which regulated gastric cancer cellular malignant behavior. Our research might inspire future therapy development to promote overall prognosis of gastric cancer patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02098-1.

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.

Expression of immunoglobulin G in human proximal tubular epithelial cells

Proximal tubular epithelial cells (PTECs) have innate immune characteristics, and produce proinflammatory factors, chemokines and complement components that drive epithelial‑mesenchymal transition (EMT). Our previous studies revealed that human mesangial cells and podocytes were able to synthesize and secrete immunoglobulin (Ig)A and IgG, respectively. The aim of the present study was to evaluate the expression of Igs in PTECs. Firstly, IgG was detected in the cytoplasm, the cell membrane and the lumen of PTECs in the normal renal cortex by immunohistochemistry. Secondly, Igγ gene transcription and V(D)J recombination were detected in single PTECs by nested PCR and Sanger sequencing. Thirdly, Igγ, Igκ and Igλ were clearly detected in an immortalized PTEC line (HK‑2) by immunostaining and western blotting, in which RP215 (an antibody that predominantly binds to non‑B cell‑derived IgG) was used. In addition, Igγ, Igκ and Igλ gene transcripts, conservative V(D)J recombination in the Igγ variable region, recombination activating gene 1/2 and activation‑induced cytidine deaminase were all detected in HK‑2 cells. These data suggested that PTECs may express IgG in a similar manner to B cells. Furthermore, IgG expression was upregulated by TGF‑β1 and may be involved in EMT.

IGHG1 induces EMT in gastric cancer cells by regulating TGF-β/SMAD3 signaling pathway

Objective: Gastric cancer is one of the most common malignant tumors in the world. IGHG1 is a differentially expressed protein screened out in gastric cancer in the early stage of the subject group. This topic explores the expression of IGHG1 in gastric cancer and the effect of IGHG1 on the proliferation, migration, invasion and EMT of gastric cancer SGC7901 cells and its mechanism of action.

Methods: Twenty cases of gastric cancer were purified by laser Capture Microdissection. The isotopic tags for relative and absolute quantification was used to label the proteins, and then analyzed and identified them by quantitative proteomics. Immunohistochemical staining method was used to detect the expression of IGHG1 protein in gastric cancer tissues. Western blot was used to detect the expression of IGHG1 in gastric cancer cells. The MTT and Petri dish clone formation experiment analyzed the effect of low expression of IGHG1 on the proliferation of SGC7901 cells. Scratch test and Transwell migration and invasion test to observe the effect of low expression of IGHG1 on the migration and invasion of SGC7901 cells. Western blot was used to detect the effect of low expression of IGHG1 on the expression of EMT-related proteins.

Results: 243 proteins related to gastric mucosal lesions were preliminarily identified. We found that IGHG1 is highly expressed in gastric cancer tissues compared with normal control tissues. IGHG1 promotes the proliferation, migration and invasion of gastric cancer cells. Compared with the control group, the expression of EMT-related proteins Vimentin, N-cadherin, TGF-β, P-SMAD3 was decreased and the expression of E-cadherin was increased after IGHG1 low expression.

Conclusions: IGHG1 induces EMT in SGC7901 cells by regulating the TGF-β/SMAD3 signaling pathway.

Single-Cell Sequencing Confirms Transcripts and VHDJH Rearrangements of Immunoglobulin Genes in Human Podocytes

Most glomerular diseases are associated with inflammation caused by deposited pathogenic immunoglobulins (Igs), which are believed to be produced by B cells. However, our previous study indicated that the human podocyte cell line can produce IgG. In this study, we aimed to confirm the transcripts and characterize the repertoires of Igs in primary podocytes at single cell level. First, single-cell RNA sequencing of cell suspensions from “normal” kidney cortexes by a 10xGenomics Chromium system detected Ig transcripts in 7/360 podocytes and Ig gene segments in 106/360 podocytes. Then, we combined nested PCR with Sanger sequencing to detect the transcripts and characterize the repertoires of Igs in 48 single podocytes and found that five classes of Ig heavy chains were amplified in podocytes. Four-hundred and twenty-nine V_HDJ_H rearrangement sequences were analyzed; podocyte-derived Igs exhibited classic V_HDJ_H rearrangements with nucleotide additions and somatic hypermutations, biased VH1 usage and restricted diversity. Moreover, compared with the podocytes from healthy control that usually expressed one class of Ig and one V_HDJ_H pattern, podocytes from patients expressed more classes of Ig, V_HDJ_H patterns and somatic hypermutations. These findings suggested that podocytes can express Igs in normal condition and increase diversity in pathological situations.

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.

High-Throughput Microbore Ultrahigh-Performance Liquid Chromatography-Ion Mobility-Enabled-Mass Spectrometry-Based Proteomics Methodology for the Exploratory Analysis of Serum Samples from Large Cohort Studies

The deployment of proteomic analysis in clinical studies represents a significant opportunity to detect and validate biomarkers in translational medicine, improve disease understanding, and provide baseline information on population health. However, comprehensive proteome studies usually employ nanoscale chromatography and often require several hours of analysis/sample. Here, we describe a high-throughput liquid chromatography tandem mass spectrometry (LC/MS/MS) methodology using 1 mm scale chromatography requiring only 15 min/sample, coupled to ion mobility-enabled mass spectrometry. The short run time effected a 6-fold increase in productivity compared with nanoscale LC/MS. The method demonstrated excellent reproducibility with retention time coefficient of variations of less than 0.05% and peak area reproducibility ranging from 5 to 15%. The 1 mm system produced similar chromatographic peak capacity values to the nanoscale miniaturized system, detecting 90% of the Escherichia coli proteins identified by the 75 μm LC/MS system (albeit based on only 75% of the peptides found by the latter). Application to the analysis of serum samples from a human prostate cancer study group resulted in the identification of a total of 533 proteins revealing the differential expression of proteins linked to patients receiving hormone-radiotherapy or undergoing surgery.

NBIGV-DB: A dedicated database of non-B cell derived immunoglobulin variable region

Immunoglobulins (Ig) are important immune molecules that possess highly diverse variable region sequences enabling antigen recognition. According to classical immune theory, B lymphocytes have been considered the only source of Ig production (B-Igs). However, accumulating evidence have suggested that Igs are also produced by many non-B cells (non-B Igs), including epithelial cells, neurons, germ cells, as well as myeloid cells of hemopoietic system. Besides acting as bona fide antibodies, Non-B Igs have alternative cellular functions, such as promotion of cell survival, adhesion and migration. More importantly, Unlike the unlimited sequence diversity of B-Igs, the non-B Igs exhibit conserved V(D)J patterns across the same lineages. To support the analysis and comparison of variable region sequences from Igs, produced by B and non-B cells, we established a database (NBIGV) constituted by a non-B Ig variable region repertoire, which includes 727,989 V_HDJ_H and VκJκ recombination sequences of non-B Igs sequenced from mouse samples. Upon database search, users can view, browse and investigate the variable region sequences of non-B Igs according to respective mice strains and tissues as well as Ig classes. Moreover, users can easily download selected sequences and/or compare sequences of interest with known non-B Ig sequences present in the database using NCBI-BLAST algorithms. Additionally, our database integrates a submission page and supplementary sample information. The NBIGV database may serve as a valuable resource for sequence analyses of Non-B Igs. NBIGV database is freely available at http://nbigv.org.

Mitochondria Autoimmunity and MNRR1 in Breast Carcinogenesis: A Review

We review here the evidence for participation of mitochondrial autoimmunity in BC inception and progression and propose a new paradigm that may challenge the prevailing thinking in oncogenesis by suggesting that mitochondrial autoimmunity is a major contributor to breast carcinogenesis and probably to the inception and progression of other solid tumors. It has been shown that MNRR1 mediated mitochondrial-nuclear function promotes BC cell growth and migration and the development of metastasis and constitutes a proof of concept supporting the participation of mitochondrial autoimmunity in breast carcinogenesis. The resemblance of the autoantibody profile in BC detected by IFA with that in the rheumatic autoimmune diseases suggested that studies on the autoantibody response to tumor associated antigens and the characterization of the mtDNA- and nDNA-encoded antigens may provide functional data on breast carcinogenesis. We also review the studies supporting the view that a panel of autoreactive nDNA-encoded mitochondrial antigens in addition to MNRR1 may be involved in breast carcinogenesis. These include GAPDH, PKM2, GSTP1, SPATA5, MFF, ncRNA PINK1-AS/DDOST as probably contributing to BC progression and metastases and the evidence suggesting that DDX21 orchestrates a complex signaling network with participation of JUND and ATF3 driving chronic inflammation and breast tumorigenesis. We suggest that the widespread autoreactivity of mtDNA- and nDNA-encoded mitochondrial proteins found in BC sera may be the reflection of autoimmunity triggered by mitochondrial and non-mitochondrial tumor associated antigens involved in multiple tumorigenic pathways. Furthermore, we suggest that mitochondrial proteins may contribute to mitochondrial dysfunction in BC even if mitochondrial respiration is found to be within normal limits. However, although the studies show that mitochondrial autoimmunity is a major factor in breast cancer inception and progression, it is not the only factor since there is a multiplex autoantibody profile targeting centrosome and stem cell antigens as well as anti-idiotypic antibodies, revealing the complex signaling network involved in breast carcinogenesis. In summary, the studies reviewed here open new, unexpected therapeutic avenues for cancer prevention and treatment of patients with cancer derived from an entirely new perspective of breast carcinogenesis.

Single-cell RNA sequencing confirms IgG transcription and limited diversity of VHDJH rearrangements in proximal tubular epithelial cells

Increasing evidence has confirmed that immunoglobulins (Igs) can be expressed in non-B cells. Our previous work demonstrated that mesangial cells and podocytes express IgA and IgG, respectively. The aim of this work was to reveal whether proximal tubular epithelial cells (PTECs) express Igs. High-throughput single-cell RNA sequencing (scRNA-seq) detected Igs in a small number of PTECs, and then we combined nested PCR with Sanger sequencing to detect the transcripts and characterize the repertoires of Igs in PTECs. We sorted PTECs from the normal renal cortex of two patients with renal cancer by FACS and further confirmed their identify by LRP2 gene expression. Only the transcripts of the IgG heavy chain were successfully amplified in 91/111 single PTECs. We cloned and sequenced 469 V_HDJ_H transcripts from 91 single PTECs and found that PTEC-derived IgG exhibited classic V_HDJ_H rearrangements with nucleotide additions at the junctions and somatic hypermutations. Compared with B cell-derived IgG, PTEC-derived IgG displayed less diversity of V_HDJ_H rearrangements, predominant VH1-24/DH2-15/JH4 sequences, biased VH1 usage, centralized VH gene segment location at the 3′ end of the genome and non-Gaussian distribution of the CDR3 length. These results demonstrate that PTECs can express a distinct IgG repertoire that may have implications for their role in the renal tubular epithelial-mesenchymal transition.

Cancer-driven IgG promotes the development of prostate cancer though the SOX2-CIgG pathway

BACKGROUND

Although androgen deprivation therapy (ADT) is the initial treatment strategy for prostate cancer (PCa), recurrent castration-resistant prostate cancer (CRPC) eventually ensues. In this study, cancer-derived immunoglobulin G (CIgG) is found to be induced after ADT, identifying CIgG as a potential CRPC driver gene.

METHODS

The expression of CIgG and its clinical significance in PCa tissue was analyzed by The Cancer Genome Atlas database and immunohistochemistry. Subsequently, the sequence features of prostate cell line VHDJH rearrangements were analyzed. We also assessed the effect of CIgG on the migratory, invasive and proliferative abilities of PCa cells in vitro and vivo. Suspended microsphere, colony formation and drug-resistant assays were performed using PC3 cells with high CIgG expression (CIgG^high ) and low CIgG expression (CIgG^-/low ), and A nonobese diabetic/severe combined immunodeficiency mouse tumor xenograft model was developed for the study of the tumorigenic effects of the different cell populations. The SOX2-CIgG signaling pathway was validated by immunohistochemistry, immunofluorescence, quantitative reverse transcription-polymerase chain reaction, Western blot, luciferase, and chromatin immunoprecipitation assays and bioinformatics analyses. Finally, we investigated the effect of RP215 inhibition on the progression of PCa in vivo using a Babl/c nude mouse xenograft model.

RESULTS

CIgG is frequently expressed in PCa and associated with clinicopathological characteristics, moreover, CIgG transcripts with unique patterns of VHDJH rearrangements are found in PCa cells. Functional analyses identified that CIgG was induced by ADT and upregulated by SOX2 (SRY (sex determining region Y)-box 2) in PCa, promoting the development of PCa. In addition, our findings underscore a novel role of CIgG signaling in the maintenance of stemness and the progression of cancer through mitogen activated protein kinase/extracellular-signal-regulated kinase and AKT in PCa. In vivo experiments further demonstrated that depleting CIgG significantly suppressed the growth of PCa cell xenografts. Furthermore, a CIgG monoclonal antibody named RP215 exhibits tumor inhibitory effect as well.

CONCLUSION

Our data suggests that CIgG could be a driver of PCa development, and that targeting the SOX2-CIgG axis may therefore inhibit PCa development after ADT.

Investigating genetic drivers of dermatomyositis pathogenesis using meta-analysis

AIMS

Dermatomyositis (DM) is a progressive, idiopathic inflammatory myopathy with poorly understood pathogenesis. A hallmark of DM is an increased risk for developing breast, ovarian, and lung cancer. Since autoantibodies against anti-TIF-1-γ, a member of the tripartite motif (TRIM) proteins, has a strong association with malignancy, we examined expression of the TRIM gene family to identify pathways that may be contributing to DM pathogenesis.

MATERIALS AND METHODS

We employed the Search Tag Analyze Resource for GEO platform to search the NCBI Gene Expression Omnibus to elucidate TRIM family gene expression as well as oncogenic drivers in DM pathology. We conducted meta-analysis of the data from human skin (60 DM vs 34 healthy) and muscle (71 DM vs 22 healthy).

KEY FINDINGS

We identified genes involved in innate immunity, antigen presentation, metabolism, and other cellular processes as facilitators of DM disease activity and confirmed previous observations regarding the presence of a robust interferon signature. Moreover, analysis of DM muscle samples revealed upregulation of TRIM14, TRIM22, TRIM25, TRIM27, and TRIM38. Likewise, analysis of DM skin samples showed upregulation of TRIM5, TRIM6, TRIM 14, TRIM21, TRIM34, and TRIM38 and downregulation of TRIM73. Additionally, we noted upregulation of oncogenes IGLC1, IFI44, POSTN, MYC, NPM1, and IDO1 and related this change to interferon signaling. While the clinical data associated with genetic data that was analyzed did not contain clinical data regarding malignancy in these cohorts, the observed genetic changes may be associated with homeostatic and signaling changes that relate to the increased risk in malignancy in DM.

SIGNIFICANCE

Our results implicate previously unknown genes as potential drivers of DM pathology and suggest certain TRIM family members may have disease-specific roles with potential diagnostic and therapeutic implications.

The Skp2 Pathway: A Critical Target for Cancer Therapy

Strictly regulated protein degradation by ubiquitin-proteasome system (UPS) is essential for various cellular processes whose dysregulation is linked to serious diseases including cancer. Skp2, a well characterized component of Skp2-SCF E3 ligase complex, is able to conjugate both K48-linked ubiquitin chains and K63-linked ubiquitin chains on its diverse substrates, inducing proteasome mediated proteolysis or modulating the function of tagged substrates respectively. Overexpression of Skp2 is observed in various human cancers associated with poor survival and adverse therapeutic outcomes, which in turn suggests that Skp2 engages in tumorigenic activity. To that end, the oncogenic properties of Skp2 are demonstrated by various genetic mouse models, highlighting the potential of Skp2 as a target for tackling cancer. In this article, we will describe the downstream substrates of Skp2 as well as upstream regulators for Skp2-SCF complex activity. We will further summarize the comprehensive oncogenic functions of Skp2 while describing diverse strategies and therapeutic platforms currently available for developing Skp2 inhibitors.

[Expression and Clinical Significance of Cancer-derived Immunoglobulin G in Non-small Cell Lung Cancer by Bioinformatics and Immunohistochemistry]

背景与目的

经典免疫学理论认为，免疫球蛋白G（immunoglobulin G, IgG）仅由B细胞合成。近年来研究发现恶性肿瘤细胞也可以合成IgG（cancer-IgG）。本研究分析了cancer-IgG在非小细胞肺癌（non-small cell lung cancer, NSCLC）中的表达及临床意义，并初步探究其机制。

方法

应用数据库分析IgG1重链编码基因（immunoglobulin heavy constant gamma 1, IGHG1）、免疫组化分析cancer-IgG在NSCLC中的表达及与预后的关系；基因富集分析（gene set enrichment analysis, GSEA）方法探究与IGHG1调控相关的信号通路。

结果

Cancer-IgG在NSCLC中的表达量显著高于正常组织，与预后呈负相关，并与患者的临床分期（P=0.042）、T分期（P=0.044）和转移（P=0.007）密切相关。GSEA分析显示，IGHG1与细胞黏附、细胞因子相互作用和趋化因子信号通路相关。

结论

在NSCLC中，cancer-IgG高表达是预后不良的因素，可能与促进肿瘤的侵袭转移相关。

Histogenesis of Merkel Cell Carcinoma: A Comprehensive Review

Merkel cell carcinoma (MCC) is a primary neuroendocrine carcinoma of the skin. This neoplasia features aggressive behavior, resulting in a 5-year overall survival rate of 40%. In 2008, Feng et al. identified Merkel cell polyomavirus (MCPyV) integration into the host genome as the main event leading to MCC oncogenesis. However, despite identification of this crucial viral oncogenic trigger, the nature of the cell in which MCC oncogenesis occurs is actually unknown. In fact, several hypotheses have been proposed. Despite the large similarity in phenotype features between MCC tumor cells and physiological Merkel cells (MCs), a specialized subpopulation of the epidermis acting as mechanoreceptor of the skin, several points argue against the hypothesis that MCC derives directly from MCs. Alternatively, MCPyV integration could occur in another cell type and induce acquisition of an MC-like phenotype. Accordingly, an epithelial as well as a fibroblastic or B-cell origin of MCC has been proposed mainly based on phenotype similarities shared by MCC and these potential ancestries. The aim of this present review is to provide a comprehensive review of the current knowledge of the histogenesis of MCC.

Human colorectal cancer cells frequently express IgG and display unique Ig repertoire

BACKGROUND

There is growing evidence proving that many human carcinomas, including colon cancer, can overexpress immunoglobulin (Ig); the non B cancer cell-derived Ig usually displayed unique V(D)J rearrangement pattern that are distinct from B cell-derived Ig. Especially, the cancer-derived Ig plays important roles in cancer initiation, progression, and metastasis. However, it still remains unclear if the colon cancer-derived Ig can display unique V(D)J pattern and sequencing, which can be used as novel target for colon cancer therapy.

AIM

To investigate the Ig repertoire features expressed in human colon cancer cells.

METHODS

Seven cancerous tissue samples of colon adenocarcinoma and corresponding noncancerous tissue samples were sorted by fluorescence-activated cell sorting using epithelial cell adhesion molecule as a marker for epithelial cells. Ig repertoire sequencing was used to analyze the expression profiles of all 5 classes of Ig heavy chains (IgH) and the Ig repertoire in colon cancer cells and corresponding normal epithelial cells.

RESULTS

We found that all 5 IgH classes can be expressed in both colon cancer cells and normal epithelial cells. Surprisingly, unlike the normal colonic epithelial cells that expressed 5 Ig classes, our results suggested that cancer cells most prominently express IgG. Next, we found that the usage of Ig in cancer cells caused the expression of some unique Ig repertoires compared to normal cells. Some V_H segments, such as V_H3-7, have been used in cancer cells, and V_H3-74 was frequently present in normal epithelial cells. Moreover, compared to the normal cell-derived Ig, most cancer cell-derived Ig showed unique V_HDJ_H patterns. Importantly, even if the same V_HDJ_H pattern was seen in cancer cells and normal cells, cancer cell-derived IgH always displayed distinct hypermutation hot points.

CONCLUSION

We found that colon cancer cells could frequently express IgG and unique IgH repertoires, which may be involved in carcinogenesis of colon cancer. The unique IgH repertoire has the potential to be used as a novel target in immune therapy for colon cancer.

Obesity, Inflammation, and Prostate Cancer

The prevalence of obesity is increasing in the world, and obesity-induced disease, insulin-resistance, cardiovascular disease, and malignancies are becoming a problem. Epidemiological studies have shown that obesity is associated with advanced prostate cancer and that obese men with prostate cancer have a poorer prognosis. Obesity induces systemic inflammation via several mechanisms. High-fat diet-induced prostate cancer progresses via adipose-secretory cytokines or chemokines. Inflammatory cells play important roles in tumor progression. A high-fat diet or obesity changes the local profile of immune cells, such as myeloid-derived suppressor cells and macrophages, in prostate cancer. Tumor-associated neutrophils, B cells, and complements may promote prostate cancer in the background of obesity. Interventions to control systemic and/or local inflammation and changes in lifestyle may also be viable therapies for prostate cancer.

Assessment of cellular and serum proteome from tongue squamous cell carcinoma patient lacking addictive proclivities for tobacco, betel nut, and alcohol: Case study

The intriguing molecular pathways involved in oral carcinogenesis are still ambiguous. The oral squamous cell carcinoma (OSCC) ranks as the most common type constituting more than 90% of the globally diagnosed oral cancers cases. The elevation in the OSCC incidence rate during past 10 years has an alarming impression on human healthcare. The major challenges associated with OSCC include delayed diagnosis, high metastatic rates, and low 5-year survival rates. The present work foundations on reverse genetic strategy and involves the identification of genes showing expressional variability in an OSCC case lacking addictive proclivities for tobacco, betel nut, and/or alcohol, major etiologies. The expression modulations in the identified genes were analyzed in 16 patients comprising oral pre-cancer and cancer histo-pathologies. The genes SCCA1 and KRT1 were found to down regulate while DNAJC13, GIPC2, MRPL17, IG-Vreg, SSFA2, and UPF0415 upregulated in the oral pre-cancer and cancer pathologies, implicating the genes as crucial players in oral carcinogenesis.

Immunization Elicits Antigen-Specific Antibody Sequestration in Dorsal Root Ganglia Sensory Neurons

The immune and nervous systems are two major organ systems responsible for host defense and memory. Both systems achieve memory and learning that can be retained, retrieved, and utilized for decades. Here, we report the surprising discovery that peripheral sensory neurons of the dorsal root ganglia (DRGs) of immunized mice contain antigen-specific antibodies. Using a combination of rigorous molecular genetic analyses, transgenic mice, and adoptive transfer experiments, we demonstrate that DRGs do not synthesize these antigen-specific antibodies, but rather sequester primarily IgG1 subtype antibodies. As revealed by RNA-seq and targeted quantitative PCR (qPCR), dorsal root ganglion (DRG) sensory neurons harvested from either naïve or immunized mice lack enzymes (i.e., RAG1, RAG2, AID, or UNG) required for generating antibody diversity and, therefore, cannot make antibodies. Additionally, transgenic mice that express a reporter fluorescent protein under the control of Igγ1 constant region fail to express Ighg1 transcripts in DRG sensory neurons. Furthermore, neural sequestration of antibodies occurs in mice rendered deficient in neuronal Rag2, but antibody sequestration is not observed in DRG sensory neurons isolated from mice that lack mature B cells [e.g., Rag1 knock out (KO) or μMT mice]. Finally, adoptive transfer of Rag1-deficient bone marrow (BM) into wild-type (WT) mice or WT BM into Rag1 KO mice revealed that antibody sequestration was observed in DRG sensory neurons of chimeric mice with WT BM but not with Rag1-deficient BM. Together, these results indicate that DRG sensory neurons sequester and retain antigen-specific antibodies released by antibody-secreting plasma cells. Coupling this work with previous studies implicating DRG sensory neurons in regulating antigen trafficking during immunization raises the interesting possibility that the nervous system collaborates with the immune system to regulate antigen-mediated responses.

Expression of immunoglobulin G in human podocytes, and its role in cell viability and adhesion

Podocyte injury occurs during the initiation and development of numerous forms of glomerular disease, and antibodies targeting podocytes have become a biomarker for diagnosis and monitoring treatment response. Accumulating evidence has suggested that immunoglobulin (Ig) is expressed in non‑B lineage cells, including epithelial cancer cells, myeloid cells and several types of normal cells. The main aim of the present study was to ascertain the expression of IgG in human podocytes and to determine its potential role in cellular bioactivity. The present study detected positive staining for IgG heavy chain (Igγ) and its subtype γ4, and the light chains κ and λ in the cytoplasm or on the membrane by immunofluorescence. In addition, positive bands were detected for Igγ, γ1, γ3, γ4, κ and λ in the lysates of a podocyte cell line by western blotting. Mass spectrometry confirmed IgG1 as an intact tetramer in the culture supernatant. Constant region transcripts of Igγ, γ1, γ3, γ4, κ and λ were identified by reverse transcription‑polymerase chain reaction, and DNA sequencing of these transcripts revealed 96‑99% similarity with Ig mRNAs in the National Center for Biotechnology Information database. Compared with the diverse gene rearrangements from B cell-derived Ig, podocyte‑derived Ig exhibited conservative V(D)J patterns in the variable regions of Igγ and κ chains. Furthermore, the present study investigated the mechanism underlying IgG production in these cells by examining the expression of recombination activating gene (RAG)1, RAG2 and activation‑induced cytidine deaminase. The expression levels of these proteins suggested that podocyte‑derived Ig and traditional Ig may be generated in a similar manner. Furthermore, small interfering RNA‑mediated downregulation of IgG expression reduced podocyte viability and adhesive capabilities. These findings suggested that IgG is expressed in podocytes and that this expression may be associated with podocyte function. Due to its potential biological and clinical significance, this phenomenon warrants further investigation.

Expression of immunoglobulin A in human mesangial cells and its effects on cell apoptosis and adhesion

IgA nephropathy (IgAN) is characterized by predominant IgA deposition in the glomerular mesangium. It has been considered that the deposited IgA is synthesized by B cells, although recent reports have suggested the implication of other cell types. Therefore, the present study investigated whether glomerular mesangial cells could produce IgA by themselves. Semi‑quantitative reverse transcription-polymerase chain reaction, and immunostaining analysis revealed that the IgA protein and gene transcripts were expressed in primary human renal mesangial cells (HRMCs). Furthermore, the IgA heavy chain (α1 and α2) and the light chain (κ and λ) were localized in the cytoplasm or were located on the cell membranes of human mesangial cells (HMCs). Mass spectrometry results indicated that Ig α1 and Ig α2 were secreted in the culture media of HMCs. The transcripts of Ig α, Ig κ and Ig λ constant regions were detected. The predominant rearrangement pattern of the variable region of Ig κ, was Vκ3‑20*01/Jκ1*01 in HMCs and Vκ1‑12*01/Jκ4*01 in HRMCs. In addition, knockdown of Ig α1 expression by small interfering RNA (siRNA) inhibited cell adhesion and promoted apoptosis. Our findings demonstrate that HMCs can express IgA, and that this expression is associated with cell functions, which may contribute to the deposition of IgA in patients with IgAN.

The roles and applications of autoantibodies in progression, diagnosis, treatment and prognosis of human malignant tumours

The existence of autoantibodies towards an individual's own proteins or nucleic acids has been established for more than 100years, and for a long period, these autoantibodies have been believed to be closely associated with autoimmune diseases. However, in recent years, researchers have become more interested in the role and application of autoantibodies in progression, diagnosis, treatment and prognosis of human malignant tumours. Over the past few decades, numerous epidemiological studies have shown that the risk of certain cancers is significantly altered (increased or decreased) in patients with autoimmune diseases, which suggests that autoantibodies may play either promoting or suppressing roles in cancer progression. The idea that autoantibodies are directly involved in tumour progression gains special support by the findings that some antibodies secreted by a variety of cancer cells can promote their proliferation and metastasis. Because the cancer cells generate cell antigenic changes (neoantigens), which trigger the immune system to produce autoantibodies, serum autoantibodies against tumour-associated antigens have been established as a novel type of cancer biomarkers and have been extensively studied in different types of cancer. The autoantibodies as biomarkers in cancer diagnosis are not only more sensitive and specific than antigens, but also could appear before clinical evidences of the tumours, thus disclosing them. The observations that cancer risk is lower in patients with some autoimmune diseases suggest that certain autoantibodies may be protective from certain cancers. Moreover, the presence of autoantibodies in healthy individuals implies that it could be safe to employ autoantibodies to treat cancer. Of note, an autoantibodies derived from lupus murine model received much attention due to their selective cytotoxicity for malignant tumour cell without harming normal ones. These studies showed the therapeutic value of autoantibodies in cancer. In this review, we revisited the pathological or protective role of autoantibodies in cancer progression, summarize the application of autoantibodies in cancer diagnosis and prognosis, and discuss the value of autoantibodies in cancer therapy. The studies established to date suggest that autoantibodies not only regulate cancer progression but also promise to be valuable instruments in oncological diagnosis and therapy.

Involvement of non-B cell-derived immunoglobulin G in the metastasis and prognosis of salivary adenoid cystic carcinoma

Cancer cell-derived immunoglobulin G (cancer-IgG) has been implicated in the pathogenesis and progression of various types of cancer. However, its role in salivary adenoid cystic carcinoma (SACC) remains unclear. The present study aimed to investigate the effects of cancer-IgG on metastasis and prognosis in 96 patients with SACC. Immunohistochemical staining showed that cancer-IgG expression was present in all 96 individual SACC tissues. Additionally, high cancer-IgG expression was significantly correlated with metastasis, nerve invasion and recurrence in SACC (P<0.05). Moreover, cancer-IgG expression was significantly correlated with the survival duration of patients with SACC (P<0.05). Proliferation, cell motility and invasion all decreased significantly following knockdown of cancer-IgG in SACC cells (P<0.05) through population-doubling time, wound healing and transwell invasion assays. Additionally, cancer-IgG-knockdown in SACC cells induced the increased expression of E-cadherin and matrix metalloproteinase 9, and promoted the epithelial-mesenchymal transition, but decreased the expression of F-actin filaments. Taken together, these results showed that the high expression of cancer-IgG was strongly associated with metastasis, recurrence and invasion in SACC, suggesting that cancer-IgG expression could serve as a useful biomarker to predict the prognosis of the disease.

Reviewing the current evidence supporting early B-cells as the cellular origin of Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a highly malignant skin cancer characterized by early metastases and poor survival. Although MCC is a rare malignancy, its incidence is rapidly increasing in the U.S. and Europe. The discovery of the Merkel cell polyomavirus (MCPyV) has enormously impacted our understanding of its etiopathogenesis and biology. MCCs are characterized by trilinear differentiation, comprising the expression of neuroendocrine, epithelial and B-lymphoid lineage markers. To date, it is generally accepted that the initial assumption of MCC originating from Merkel cells (MCs) is unlikely. This is owed to their post-mitotic character, absence of MCPyV in MCs and discrepant protein expression pattern in comparison to MCC. Evidence from mouse models suggests that epidermal/dermal stem cells might be of cellular origin in MCC. The recently formulated hypothesis of MCC originating from early B-cells is based on morphology, the consistent expression of early B-cell lineage markers and the finding of clonal immunoglobulin chain rearrangement in MCC cells. In this review we elaborate on the cellular ancestry of MCC, the identification of which could pave the way for novel and more effective therapeutic regimens.