A novel human Fab antibody for Trop2 inhibits breast cancer growth in vitro and in vivo

Selection of trophoblast cell surface antigen 2-targeted aptamer for the development of cytotoxic aptamer-drug conjugate

Trophoblast cell surface antigen 2 expressed in several malignant cancers promotes tumor growth and metastasis via several signal transduction pathways. Trop2 is reputed as a prospective biomarker and therapeutic target. Trophoblast cell surface antigen 2-targeted agents, including antibodies, antibody conjugates and therapeutic combinations, could be utilized to fight cancers. To develop an effective drug targeting strategy, we resorted to a new trophoblast cell surface antigen 2-targeted anticancer treatment through aptamer conjugated with chemotherapeutic drug. This study identified trophoblast cell surface antigen 2-specific ssDNA aptamers using engineered trophoblast cell surface antigen 2 overexpression cells for cell-SELEX. The obtained ssDNA aptamer bound to trophoblast cell surface antigen 2 overexpressed cells with nanomolar affinity and was specific for several tumor cell types which express trophoblast cell surface antigen 2 abundantly. Significant cytotoxicity against HT29 cell by the conjugate of trophoblast cell surface antigen 2 aptamer and Emtansine was observed while resulting negligible therapeutic effect on human normal intestinal epithelial cell line HIEC in vitro, indicating that the conjugate shows potential as a promising therapeutic agent. Furthermore, the isolated aptamer demonstrated the ability for the targeted delivery, resulting excellent therapeutic effectiveness of aptamer-drug conjugate for xenograft tumor model of mice with human colorectal cancer.

Modulating autophagy to boost the antitumor efficacy of TROP2-directed antibody-drug conjugate in pancreatic cancer

Pancreatic cancer, characterized by a dismal prognosis and limited treatment options, persists as a formidable challenge in oncology. Trophoblast cell surface antigen 2 (TROP2)-directed antibody-drug conjugates have achieved great success in solid tumors such as breast cancer and uroepithelial carcinoma. However, their efficacy against pancreatic cancer was insufficient in clinical trials, necessitating an imperative exploration of underlying mechanisms and new therapeutic strategies. In this study, we indicated that αTROP2-MMAE, an antibody-drug conjugate targeting TROP2, induced apoptosis through the caspase-9/PARP pathway and exerted potent antitumor effects against TROP2-positive pancreatic cancer. Simultaneously, RNA sequencing suggested significant changes in autophagy after αTROP2-MMAE treatment. The formation of autophagosomes and activation of autophagic flux were markedly induced through mechanisms associated with suppressing the activation of the Akt/mTOR pathway. The addition of pharmacological inhibitors of autophagy enhanced the cytotoxicity and apoptosis caused by αTROP2-MMAE, revealing the cytoprotective role of autophagy in TROP2-positive pancreatic cancer. In the subcutaneous xenograft model using BxPC3 cells, the combined administration of αTROP2-MMAE and an autophagy inhibitor elevated the tumor inhibition rate of αTROP2-MMAE from 71.6 % to 99.0 %, resulting in the eradication of tumors in half of the mice. Collectively, our research demonstrated for the first time the cytoprotective role of autophagy in TROP2-targeted antibody-drug conjugate therapy for pancreatic cancer, providing new perspectives for mechanistic exploration and therapeutic strategies in the treatment of pancreatic cancer.

Trop2-targeted therapy in breast cancer

Human trophoblastic cell surface antigen 2 (Trop2) is a glycoprotein, a cellular marker of trophoblastic and stem cells, and a calcium signaling transducer involved in several signaling pathways, leading to the proliferation, invasion, and metastasis of tumors. It is expressed at a low level in normal epithelial cells, but at a high level in many tumors, making it an ideal target for cancer therapy. According to previous literature, Trop2 is broadly expressed in all breast cancer subtypes, especially in triple negative breast cancer (TNBC). Several clinical trials have demonstrated the effectiveness of Trop2-targeted therapy in breast cancer. Sacituzumab govitecan (SG) is a Trop2-targeted antibody-drug conjugate (ADC) that has been approved for the treatment of metastatic TNBC and hormone receptor-positive (HR+) and human epidermal growth factor receptor 2-negative (HER2-) breast cancer. This article reviews the structure and function of Trop2, several major Trop2-targeted ADCs, other appealing novel Trop2-targeted agents and relevant clinical trials to provide a landscape of how Trop2-targeted treatments will develop in the future.

Ribosomal Incorporation of Lithocholic Acid into Peptides for the De Novo Discovery Of Peptide-Lithocholic Acid Hybrid Macrocyclic Peptides

Peptide-bile acid hybrids offer promising drug candidates due to enhanced pharmacological properties, such as improved protease resistance and oral bioavailability. However, it remains unknown whether bile acids can be incorporated into peptide chains by the ribosome to produce a peptide-bile acid hybrid macrocyclic peptide library for target-based de novo screening. In this study, we achieved the ribosomal incorporation of lithocholic acid (LCA)-d-tyrosine into peptide chains. This led to the construction of a peptide-LCA hybrid macrocyclic peptide library, which enabled the identification of peptides TP-2C-4L3 (targeting Trop2) and EP-2C-4L5 (targeting EphA2) with strong binding affinities. Notably, LCA was found to directly participate in binding to EphA2 and confer on the peptides improved stability and resistance to proteases. Cell staining experiments confirmed the high specificity of the peptides for targeting Trop2 and EphA2. This study highlights the benefits of LCA in peptides and paves the way for de novo discovery of stable peptide-LCA hybrid drugs.

Comparison of Anti-Trop2 Extracellular Domain Antibodies Generated Against Peptide and Protein Immunogens for Targeting Trop2-Positive Tumour Cells

Trophoblast antigen 2 (Trop2) is a transmembrane glycoprotein upregulated in multiple solid tumours. Trop2-based passive immunotherapies are in clinical trials, while Trop2 targeting CAR-T cell-based therapies are also reported. Information about its T- and B-cell epitopes is needed for it to be pursued as an active immunotherapeutic target. This study focused on identification of immunodominant epitopes in the Trop2 extracellular domain (ECD) that can mount an efficient anti-Trop2 antibody response. In silico analysis using various B-cell epitope prediction tools was carried out to identify linear and conformational B-cell epitopes in the ECD of Trop2. Three linear peptide immunogens were shortlisted and synthesized. Along with linear peptides, truncated Trop2 ECD that possesses combination of linear and conformational epitopes was also selected. Recombinant protein immunogen was produced in 293-F suspension culture system and affinity purified. Antisera against different immunogens were characterized by ELISA and Western blotting. Two anti-peptide antisera detected recombinant and ectopically expressed Trop2 protein; however, they were unable to recognize the endogenous Trop2 protein expressed by cancer cells. Antibodies against truncated Trop2 ECD could bind to the endogenous Trop2 expressed on the surface of cancer cells. In addition to their high avidity, these polyclonal anti-sera against truncated Trop2 protein also mediated antibody-dependent cell-mediated cytotoxicity (ADCC). In summary, our comparative analysis demonstrated the utility of truncated Trop2 ECD as a promising candidate to be pursued as an active immunotherapeutic molecule against Trop2-positive cancer cells.

The expression characteristic and prognostic role of Siglec-15 in lung adenocarcinoma

Sialic acid-binding immunoglobulin-like lectin-15 (Siglec-15) has been identified as an immune suppressor and a promising candidate for immunotherapy of cancer management. However, the association between Siglec-15 expression and clinicopathological features of lung adenocarcinoma (LUAD), especially the prognostic role, is not fully elucidated. In this present study, a serial of bioinformatics analyses in both tissue and cell levels were conducted to provide an overview of Siglec-15 expression. Real-time quantitative PCR (qPCR) test, western blotting assay, and immunohistochemistry (IHC) analyses were conducted to evaluate the expression of Siglec-15 in LUAD. Survival analysis and Kaplan-Meier curve were employed to describe the prognostic parameters of LUAD. The results of bioinformatics analyses demonstrated the up-regulation of Siglec-15 expression in LUAD. The data of qPCR, western blotting, and IHC analyses further proved that the expression of Siglec-15 in LUAD tissues was significantly increased than that in noncancerous tissues. Moreover, the expression level of Siglec-15 protein in LUAD was substantially associated with TNM stage. LUAD cases with up-regulated Siglec-15 expression, positive N status, and advance TNM stage suffered a critical unfavorable prognosis. In conclusion, Siglec-15 could be identified as a novel prognostic biomarker in LUAD and targeting Siglec-15 may provide a promising strategy for LUAD immunotherapy.

Targeting Trop2 by Bruceine D suppresses breast cancer metastasis by blocking Trop2/β-catenin positive feedback loop

INTRODUCTION

Tumor-associated calcium signal transducer 2 (Trop2) has been used as a transport gate for cytotoxic agents into cells in antibody-drug conjugate designs because of its expression in a wide range of solid tumors. However, the specific role of Trop2 itself in breast cancer progression remains unclear and small molecules targeting Trop2 have not yet been reported.

OBJECTIVES

To screen small molecules targeting Trop2, and to reveal its pharmacological effects and the molecular mechanisms of action.

METHODS

Small molecule targeting Trop2 was identified by cell membrane chromatography, and validated by cellular thermal shift assay and point mutation analyses. We investigated the pharmacological effects of Trop2 inhibitor using RNA-seq, human foreskin fibroblast (HFF)-derived extracellular matrix (ECM), Matrigel drop invasion assays, colony-forming assay, xenograft tumor model, 4T1 orthotopic metastasis model and 4T1 experimental metastasis model. The molecular mechanism was determined using immunoprecipitation, mass spectrometry, immunofluorescence, immunohistochemistry and Western blotting.

RESULTS

Here we identified Bruceine D (BD) as the inhibitor of Trop2, and demonstrated anti-metastasis effects of BD in breast cancer. Notably, Lys307 and Glu310 residues of Trop2 acted as critical sites for BD binding. Mechanistically, BD suppressed Trop2-induced cancer metastasis by blocking the formation of Trop2/β-catenin positive loop, in which the Trop2/β-catenin complex prevented β-catenin from being degraded via the ubiquitin-proteosome pathway. Destabilized β-catenin caused by BD reduced nucleus translocation, leading to the reduction of transcription of Trop2, the reversal of epithelial-mesenchymal transition (EMT) process, and the inhibition of ECM remodeling, further inhibiting cancer metastasis. Additionally, the inhibitory effects of BD on lung metastatic colonization and the beneficial effects of BD on prolongation of survival were validated in 4T1 experimental metastasis model.

CONCLUSIONS

These results support the tumor-promoting role of Trop2 in breast cancer by stabilizing β-catenin in Trop2/β-catenin positive loop, and suggest Bruceine D as a promising candidate for Trop2 inhibition.

Cytotoxicity of fourth-generation anti-Trop2 CAR-T cells against breast cancer

The treatment of breast cancer (BC) remains a formidable challenge due to the emergence of drug resistance, necessitating the exploration of innovative strategies. Chimeric antigen receptor (CAR)-T cell therapy, a groundbreaking approach in hematologic malignancies, is actively under investigation for its potential application in solid tumors, including BC. Trophoblast cell surface antigen 2 (Trop2) has emerged as a promising immunotherapeutic target in various cancers and is notably overexpressed in BC. To enhance therapeutic efficacy in BC, a fourth-generation CAR (CAR4) construct was developed. This CAR4 design incorporates an anti-Trop2 single-chain variable fragment (scFv) fused with three costimulatory domains -CD28/4-1BB/CD27, and CD3ζ. Comparative analysis with the conventional second-generation CAR (CAR2; 28ζ) revealed that anti-Trop2 CAR4 T cells exhibited heightened cytotoxicity and interferon-gamma (IFN-γ) production against Trop2-expressing MCF-7 cells. Notably, anti-Trop2 CAR4-T cells demonstrated superior long-term cytotoxic functionality and proliferative capacity. Crucially, anti-Trop2 CAR4-T cells displayed specific cytotoxicity against Trop2-positive BC cells (MDA-MB-231, HCC70, and MCF-7) in both two-dimensional (2D) and three-dimensional (3D) culture systems. Following antigen-specific killing, these cells markedly secreted interleukin-2 (IL-2), tumor necrosis factor-alpha (TNF-α), IFN-γ, and Granzyme B compared to non-transduced T cells. This study highlights the therapeutic potential of anti-Trop2 CAR4-T cells in adoptive T cell therapy for BC, offering significant promise for the advancement of BC treatment strategies.

Diagnostic and prognostic utility of TROP-2, SLP-2, and CXCL12 expression in papillary thyroid carcinoma

BACKGROUND

Papillary thyroid carcinoma (PTC) is the most frequent thyroid malignancy. Histopathological examination is widely accepted as the gold standard test for the diagnosis of PTC. However, the histopathological examination sometimes can't differentiate PTC from other thyroid diseases. Differentiating PTC from other thyroid diseases is essential for a therapeutic approach and prognosis.

OBJECTIVES

The current study was performed to investigate the utility of TROP-2, SPL-2, and CXCL12 mRNA and protein expression in discriminating PTC from other thyroid diseases that mimic PTC.

METHODS

The current study was performed on 75 cases of surgically resected thyroid glands. The cases were distributed in two groups: the PTC group and the non-PTC group. The PTC group consisted of 35 cases (25 patients of the classic PTC variant and 10 patients of the PTC follicular variant). The non-PTC group consisted of 40 cases (10 cases were multinodular goiter, 5 cases were Graves' disease, 5 cases were Hashimoto thyroiditis, 15 patients were follicular adenoma (FA) and 5 cases were follicular carcinoma). TROP-2, SPL-2, and CXCL12 mRNA expression were estimated by qRT-PCR, and protein expression was estimated by immunohistochemistry.

RESULTS

There were upregulated TROP-2, SPL-2, and CXCL12 mRNA and protein expressions in PTC compared to non-PTC (P< 0.001, for each). There was a statistically significant upregulation in the mRNA expression of the three genes among PTC cases with larger tumor sizes (P< 0.001, for each), those with tumor stages III and IV (P= 0.008, 0.002 and < 0.001 respectively), and those with LN metastasis (P< 0.001, for each). Moreover, there was a statistically significant upregulation in CXCL-12 gene expression among PTC cases with extra-thyroid extension (P< 0.001).

CONCLUSION

mRNA expression of TROP-2, SPL-2, and CXCL12 among PTC cases increased in larger tumor size, tumor stages III and IV, and LN metastasis. Moreover, there was an increase in CXCL-12 gene expression among PTC cases with extra-thyroid extension. Thus, TROP-2, SPL-2, and CXCL12 expressions could be possible diagnostic and prognostic markers in PTC.

Targeting Trop2 in solid tumors: a look into structures and novel epitopes

Trophoblast cell surface antigen 2 (Trop2) exhibits limited expression in normal tissues but is over-expressed across various solid tumors. The effectiveness of anti-Trop2 antibody-drug conjugate (ADC) in managing breast cancer validates Trop2 as a promising therapeutic target for cancer treatment. However, excessive toxicity and a low response rate of ADCs pose ongoing challenges. Safer and more effective strategies should be developed for Trop2-positive cancers. The dynamic structural attributes and the oligomeric assembly of Trop2 present formidable obstacles to the progression of innovative targeted therapeutics. In this review, we summarize recent advancements in understanding Trop2's structure and provide an overview of the epitope characteristics of Trop2-targeted agents. Furthermore, we discuss the correlation between anti-Trop2 agents' epitopes and their respective functions, particularly emphasizing their efficacy and specificity in targeted therapies.

The Relationship between Trop-2, Chemotherapeutic Drugs, and Chemoresistance

Trop-2 is a highly conserved one-pass transmembrane mammalian glycoprotein that is normally expressed in tissues such as the lung, intestines, and kidney during embryonic development. It is overexpressed in many epithelial cancers but is absent in non-epithelial tumors. Trop-2 is an intracellular calcium signal transducer that participates in the promotion of cell proliferation, migration, invasion, metastasis, and probably stemness. It also has some tumor suppressor effects. The pro-tumoral actions have been thoroughly investigated and reported. However, Trop-2's activity in chemoresistance is less well known. We review a possible relationship between Trop-2, chemotherapy, and chemoresistance. We conclude that there is a clear role for Trop-2 in some specific chemoresistance events. On the other hand, there is no clear evidence for its participation in multidrug resistance through direct drug transport. The development of antibody conjugate drugs (ACD) centered on anti-Trop-2 monoclonal antibodies opened the gates for the treatment of some tumors resistant to classic chemotherapies. Advanced urothelial tumors and breast cancer were among the first malignancies for which these ACDs have been employed. However, there is a wide group of other tumors that may benefit from anti-Trop-2 therapy as soon as clinical trials are completed.

Therapeutic Targets of Monoclonal Antibodies Used in the Treatment of Cancer: Current and Emerging

Cancer is one of the leading global causes of death and disease, and treatment options are constantly evolving. In this sense, the use of monoclonal antibodies (mAbs) in immunotherapy has been considered a fundamental aspect of modern cancer therapy. In order to avoid collateral damage, it is indispensable to identify specific molecular targets or biomarkers of therapy and/or diagnosis (theragnostic) when designing an appropriate immunotherapeutic regimen for any type of cancer. Furthermore, it is important to understand the currently employed mAbs in immunotherapy and their mechanisms of action in combating cancer. To achieve this, a comprehensive understanding of the biology of cancer cell antigens, domains, and functions is necessary, including both those presently utilized and those emerging as potential targets for the design of new mAbs in cancer treatment. This review aims to provide a description of the therapeutic targets utilized in cancer immunotherapy over the past 5 years, as well as emerging targets that hold promise as potential therapeutic options in the application of mAbs for immunotherapy. Additionally, the review explores the mechanisms of actin of the currently employed mAbs in immunotherapy.

Novel chimeric antigen receptor T cell-based immunotherapy: a perspective for triple-negative breast cancer

Triple-negative breast cancer (TNBC) is highly aggressive and does not express estrogen receptor (ER), progesterone (PR), or human epidermal growth factor receptor 2 (HER2). It has a poor prognosis, and traditional endocrine and anti-HER2 targeted therapies have low efficacy against it. In contrast, surgery, radiotherapy, and/or systemic chemotherapy are relatively effective at controlling TNBC. The resistance of TNBC to currently available clinical therapies has had a significantly negative impact on its treatment outcomes. Hence, new therapeutic options are urgently required. Chimeric antigen receptor T cell (CAR-T) therapy is a type of immunotherapy that integrates the antigen specificity of antibodies and the tumor-killing effect of T cells. CAR-T therapy has demonstrated excellent clinical efficacy against hematological cancers. However, its efficacy against solid tumors such as TNBC is inadequate. The present review aimed to investigate various aspects of CAR-T administration as TNBC therapy. We summarized the potential therapeutic targets of CAR-T that were identified in preclinical studies and clinical trials on TNBC. We addressed the limitations of using CAR-T in the treatment of TNBC in particular and solid tumors in general and explored key strategies to overcome these impediments. Finally, we comprehensively examined the advancement of CAR-T immunotherapy as well as countermeasures that could improve its efficacy as a TNBC treatment and the prognosis of patients with this type of cancer.

TROP-2 is widely expressed in vulvar squamous cell carcinoma and represents a potential new therapeutic target

PURPOSE

Vulvar squamous cell carcinoma (VSCC) is a rare malignancy of the female genital tract with increasing incidence rates. Etiologically, HPV-dependent and HPV-independent VSCC are distinguished. Surgical treatment and/or radiotherapy represent the therapeutic mainstay for localized disease. For recurrent or metastatic VSCC, treatment options are limited. Research has identified trophoblast cell surface antigen 2 (TROP-2) to be broadly expressed across different tumor entities. The aim of the present study was to systematically investigate the expression of TROP-2 in VSCC.

METHODS

TROP-2 protein expression was investigated by immunohistochemistry in a cohort comprising n = 103 patients with primary VSCC. A four-tier scoring system (0: no staining, 1 + : low staining, 2 + : moderate staining, 3 + : high staining) was applied for quantification of protein expression. For further analyses, two groups (low TROP-2 expression: 0/1 + ; high TROP-2 expression: 2 + /3 +) were generated. The entire study cohort, as well as HPV-dependent and HPV-independent VSCC were considered separately.

RESULTS

In the entire VSCC study cohort, TROP-2 expression was present in 97.1% of all cases (n = 100) with 74.8% displaying high TROP-2 expression (2 + /3 +). Only 2.9% of tumors showed absent TROP-2 expression. Of note, all HPV-dependent VSCC (n = 18) demonstrated high TROP-2 expression (2 + /3 +). In the subgroup of HPV-independent VSCC (n = 70), high TROP-2 expression was associated with favorable clinical outcomes based on log rank test and univariate cox analysis.

CONCLUSION

TROP-2 protein expression is of prognostic value in HPV-independent VSCC. The broad expression of TROP-2 in VSCC indicates the TROP-2 directed ADC Sacituzumab govitecan as a potential new therapeutic strategy for VSCC patients.

Engineering c-Met-CAR NK-92 cells as a promising therapeutic candidate for lung adenocarcinoma

Mesenchymal-epithelial transition factor (C-Met) has been acknowledged as a significant therapeutic target for treating lung adenocarcinoma (LUAD). However, the potential application of chimeric antigen receptors (CAR)-modified natural killer (NK) cells targeting c-Met in LUAD is rarely explored. In this study, bioinformatic databases were searched and a tissue microarray (TMA) was enrolled to investigate expression status and prognostic role of c-Met in LUAD. Then, four types of c-Met-CAR structures were designed and prepared. The engineering CAR-NK cells containing c-Met-CARs were transfected, verified and characterized. The tumor-inhibitory role of c-Met-CAR-NK cells was finally evaluated in vitro and in vivo. The results demonstrated that c-Met expression elevated and confirmed that high c-Met expression was significantly associated with unfavorable prognosis in LUAD. Then, C-Met-CAR-NK cells were successfully constructed and DAP10 designed in CAR structure was a favorable stimulator for NK cell activation. CCN4 containing DAP10 co-stimulator exhibited the strongest cytotoxicity compared with other CAR-NK cells. Furthermore, CCN4 cells also exerted the prominent tumor-inhibitory effect on xenograft tumor growth. Collectively, this study suggests that DAP10 is a potent stimulator in CAR structure for NK cell activation, and CCN4-based immunotherapy may represent a promising strategy for the treatment of c-Met-positive LUAD.

Upregulation of Actin-Related Protein 2 (ACTR2) Exacerbated the Malignancy of Diffuse Large B-Cell Lymphoma through Activating Wnt Signaling

This investigation mainly explores the roles of actin-related protein 2 (ACTR2) in diffuse large B-cell lymphoma (DLBCL). We first assessed the level of ACTR2 and its association with the overall survival (OS) of DLBCL. The results indicated that ACTR2 was upregulated in DLBCL and was associated with unfavorable prognosis of DLBCL. Next, the effect of ACTR2 knockdown or overexpression on DLBCL was evaluated in vitro. Our investigation revealed that ACTR2 depletion inhibited the malignant behaviors of DLBCL cells; whereas, ACTR2 abundance promoted those behaviors. Besides, ACTR2 activated the Wnt signaling in DLBCL and exerted its oncogenic influence on DLBCL through Wnt signaling in vitro and in vivo. To summarize, our study implicated that ACTR2 was a promising therapeutic target for DLBCL, which might become a novel direction to improve our understanding on DLBCL.

Trop-2 as a Therapeutic Target in Breast Cancer

The emergence of Trop-2 as a therapeutic target has given rise to new treatment paradigms for the treatment of patients with advanced and metastatic breast cancer. Trop-2 is most highly expressed in triple negative breast cancer (TNBC), but the receptor is found across all breast cancer subtypes. With sacituzumab govitecan, the first FDA-approved, Trop-2 inhibitor, providing a survival benefit in patients with both metastatic TNBC and hormone receptor positive breast cancer, additional Trop-2 directed therapies are under investigation. Ongoing studies of combination regimens with immunotherapy, PARP inhibitors, and other targeted agents aim to further harness the effect of Trop-2 inhibition. Current investigations are also underway in the neoadjuvant and adjuvant setting to evaluate the therapeutic benefit of Trop-2 inhibition in patients with early stage disease. This review highlights the significant impact the discovery Trop-2 has had on our patients with heavily pretreated breast cancer, for whom few treatment options exist, and the future direction of novel Trop-2 targeted therapies.

Advances in Trop2-targeted therapy: Novel agents and opportunities beyond breast cancer

Trop2 is a transmembrane glycoprotein and calcium signal transducer with limited expression in normal human tissues. It is consistently overexpressed in a variety of malignant tumors and participates in several oncogenic signaling pathways that lead to tumor development, invasion, and metastasis. As a result, Trop2 has become an attractive therapeutic target in cancer treatment. The anti-Trop2 antibody-drug conjugate (Trodelvy™, sacituzumab govitecan) has been approved to treat metastatic triple-negative breast cancer. However, it is still unclear whether the success observed in Trop2-positive breast cancer could be replicated in other tumor types, owing to the differences in the expression levels and functions of Trop2 across cancer types. In this review, we summarize the recent progress on the structures and functions of Trop2 and highlight the potential diagnostic and therapeutic value of Trop2 beyond breast cancer. In addition, the promising novel Trop2-targeted agents in the clinic were discussed, which will likely alter the therapeutic landscape of Trop2-positive tumors in the future.

Trophoblast Cell Surface Antigen 2 gene (TACSTD2) expression in primary breast cancer

PURPOSE

Trophoblast Cell Surface Antigen 2 (TROP2) is a glycoprotein expressed in many cancers. A TROP2 antibody-drug conjugate (ADC) was effective in metastatic triple-negative breast cancer (TNBC). We studied TROP2 gene (TACSTD2) expression and associations with tumor and clinical characteristics, as well as selected external genes in primary breast cancer.

METHODS

TACSTD2 gene expression was evaluated using microarray data from I-SPY 1 (n = 149), METABRIC (n = 1992), and TCGA (n = 817). Associations with clinical features (Kruskal-Wallis test, all datasets), chemotherapy response (Wilcoxon rank sum test, I-SPY 1), recurrence free survival (Cox proportional hazard model, I-SPY 1 and METABRIC), and selected genes (Pearson correlations, all datasets) were determined.

RESULTS

TACSTD2 gene expression was detectable in all breast cancer subtypes, with a wide range of expression (all datasets). TACSTD2 gene expression was lower in HER2 + than HR + /HER2- and TNBC (METABRIC: p = 0.03, TCGA p = 0.007), and in HER2 + enriched and luminal B breast cancer (METABRIC: p < 0.001, TCGA: p < 0.001). TACSTD2 expression was higher in grade I vs. II/III tumors (METABRIC: p < 0.001). No association with chemotherapy response (I-SPY 1) or recurrence free survival (I-SPY 1 and METABRIC) was seen. TACSTD2 has significant positive correlations with the expression of epithelial/adhesion genes and proliferative genes, but was inversely correlated with immune genes.

CONCLUSION

TACSTD2 gene expression was seen in all breast cancer subtypes particularly luminal A and TNBC, and correlated with the expression of genes involved in cell epithelial transformation, adhesion, and proliferation, which contribute to tumor growth. These results support the investigation of TROP2 ADC in all subtypes of breast cancer.

Sacituzumab Govitecan-hziy in Breast Cancer

Trophoblast cell-surface antigen-2 (Trop-2) is a transmembrane calcium signal transducer and its overexpression is common in many types of malignant epithelial tumors, including breast cancer (BC). Sacituzumab govitecan-hziy (SG), the anti-Trop-2 antibody-drug conjugate, resulted in a significant survival benefit over chemotherapy in patients with metastatic triple-negative breast cancer (mTNBC). The greatest efficacy was observed in those who had a medium or high Trop-2 score. However, the importance of Trop-2 as a potential predictive factor requires further research. Elderly patients also appear to benefit from treating with SG. While the early results are encouraging, the ultimate benefit of SG in patients with brain metastases has yet to be determined. Early phase studies have shown that SG is also active in hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) metastatic BC. The most common side effects of SG are nausea, neutropenia and diarrhea. Currently, several clinical trials are in progress with SG in monotherapy and in combination treatment for various types of BC. Taken together, SG should be considered as a new standard of care in patients with pretreated mTNBC. This review summarizes the development and highlights recent advances of the SG in BC.

Recent advances in trophoblast cell-surface antigen 2 targeted therapy for solid tumors

Trophoblast cell-surface antigen 2 (Trop 2) is a transmembrane glycoprotein that is highly expressed in various cancer types with relatively low or no baseline expression in most normal tissues. Its overexpression is associated with tumor growth and poor prognosis; Trop 2 is, therefore, an ideal therapeutic target for epithelial cancers. Several Trop 2 targeted therapeutics have recently been developed for the treatment of cancers, such as anti-Trop 2 antibodies and antibody-drug conjugates (ADCs), as well as Trop 2-specific cell therapy. In particular, the safety and clinical benefit of Trop 2-based ADCs have been demonstrated in clinical trials across multiple tumor types, including those with limited treatment options, such as triple-negative breast cancer, platinum-resistant urothelial cancer, and heavily pretreated non-small cell lung cancer. In this review, we elaborate on recent advances in Trop 2 targeted modalities and provide an overview of novel insights for future developments in this field.

Impact of Endocytosis Mechanisms for the Receptors Targeted by the Currently Approved Antibody-Drug Conjugates (ADCs)-A Necessity for Future ADC Research and Development

Biologically-based therapies increasingly rely on the endocytic cycle of internalization and exocytosis of target receptors for cancer therapies. However, receptor trafficking pathways (endosomal sorting (recycling, lysosome localization) and lateral membrane movement) are often dysfunctional in cancer. Antibody-drug conjugates (ADCs) have revitalized the concept of targeted chemotherapy by coupling inhibitory antibodies to cytotoxic payloads. Significant advances in ADC technology and format, and target biology have hastened the FDA approval of nine ADCs (four since 2019). Although the links between aberrant endocytic machinery and cancer are emerging, the impact of dysregulated internalization processes of ADC targets and response rates or resistance have not been well studied. This is despite the reliance on ADC uptake and trafficking to lysosomes for linker cleavage and payload release. In this review, we describe what is known about all the target antigens for the currently approved ADCs. Specifically, internalization efficiency and relevant intracellular sorting activities are described for each receptor under normal processes, and when complexed to an ADC. In addition, we discuss aberrant endocytic processes that have been directly linked to preclinical ADC resistance mechanisms. The implications of endocytosis in regard to therapeutic effectiveness in the clinic are also described. Unexpectedly, information on endocytosis is scarce (absent for two receptors). Moreover, much of what is known about endocytosis is not in the context of receptor-ADC/antibody complexes. This review provides a deeper understanding of the pertinent principles of receptor endocytosis for the currently approved ADCs.

Proteomic Characterization of Cytoplasmic Lipid Droplets in Human Metastatic Breast Cancer Cells

One of the characteristic features of metastatic breast cancer is increased cellular storage of neutral lipid in cytoplasmic lipid droplets (CLDs). CLD accumulation is associated with increased cancer aggressiveness, suggesting CLDs contribute to metastasis. However, how CLDs contribute to metastasis is not clear. CLDs are composed of a neutral lipid core, a phospholipid monolayer, and associated proteins. Proteins that associate with CLDs regulate both cellular and CLD metabolism; however, the proteome of CLDs in metastatic breast cancer and how these proteins may contribute to breast cancer progression is unknown. Therefore, the purpose of this study was to identify the proteome and assess the characteristics of CLDs in the MCF10CA1a human metastatic breast cancer cell line. Utilizing shotgun proteomics, we identified over 1500 proteins involved in a variety of cellular processes in the isolated CLD fraction. Interestingly, unlike other cell lines such as adipocytes or enterocytes, the most enriched protein categories were involved in cellular processes outside of lipid metabolism. For example, cell-cell adhesion was the most enriched category of proteins identified, and many of these proteins have been implicated in breast cancer metastasis. In addition, we characterized CLD size and area in MCF10CA1a cells using transmission electron microscopy. Our results provide a hypothesis-generating list of potential players in breast cancer progression and offers a new perspective on the role of CLDs in cancer.

EphA2: A promising therapeutic target in breast cancer

Ephrin type-A receptor 2 (EphA2), a receptor tyrosine kinase, is overexpressed in human breast cancers often linked to poor patient prognosis. Accumulating evidence demonstrates that EphA2 plays important roles in several critical processes associated with malignant breast progression, such as proliferation, survival, migration, invasion, drug resistance, metastasis, and angiogenesis. As its inhibition through multiple approaches can inhibit the growth of breast cancer and restore drug sensitivity, EphA2 has become a promising therapeutic target for breast cancer treatment. Here, we summarize the expression, functions, mechanisms of action, and regulation of EphA2 in breast cancer. We also list the potential therapeutic strategies targeting EphA2. Furthermore, we discuss the future directions of studying EphA2 in breast cancer.

Pre-eclampsia predictive ability of maternal miR-125b: a clinical and experimental study

Pre-eclampsia (PE) is a systemic maternal syndrome affecting 2-8% of pregnancies worldwide and involving poor placental perfusion and impaired blood supply to the foetus. It manifests after the 20th week of pregnancy as new-onset hypertension and substantial proteinuria and is responsible for severe maternal and newborn morbidity and mortality. Identifying biomarkers that predict PE onset prior to its establishment would critically help treatment and attenuate outcome severity. MicroRNAs are ubiquitous gene expression modulators found in blood and tissues. Trophoblast cell surface antigen (Trop)-2 promotes cell growth and is involved in several cancers. We assessed the PE predictive ability of maternal miR-125b in the first trimester of pregnancy by measuring its plasma levels in women with normal pregnancies and with pregnancies complicated by PE on the 12th week of gestation. To gain insight into PE pathogenesis we investigated whether Trop-2 is targeted by miR-125b in placental tissue. Data analysis demonstrated a significant association between plasma miR-125b levels and PE, which together with maternal body mass index before pregnancy provided a predictive model with an area under the curve of 0.85 (95% confidence interval, 0.70-1.00). We also found that Trop-2 is a target of miR-125b in placental cells; its localization in the basal part of the syncytiotrophoblast plasma membrane suggests a role for it in the early onset of PE. Altogether, maternal miR-125b proved a promising early biomarker of PE, suggesting that it may be involved in placental development through its action on Trop-2 well before the clinical manifestations of PE.

Could trop-2 overexpression indicate tumor aggressiveness among prostatic adenocarcinomas?

BACKGROUND

TROP-2, a novel marker of trophoblastic cells, is being widely analyzed for its possible role in carcinogenesis and clinical behavior of various carcinomas. In this study, we aimed to evaluate the relationship between clinicopathologic parameters and TROP2 expression in prostatic adenocarcinomas.

METHODS

101 prostatic adenocarcinomas treated by radical prostatectomy in our hospital between 2013 and 2018 were reviewed retrospectively for histopathological features, and one representative block of each case was stained with TROP2 antibody. Histopathologic prognostic features were assessed for their relationship with TROP2 expression.

RESULTS

The mean age was found as 64.11 year. TROP2 was stained in over 10% of the tumoral cells in 64 (63.4.%) cases. Gleason grade group, perineural invasion, lymphovascular invasion, ganglionic and seminal vesicle involvement, lateral and basal surgical margin positivity showed a significant relationship with TROP2 staining.

CONCLUSION

TROP2 is overexpressed in various human cancers and TROP2 overexpression appears to correlate with poor prognosis leading to the suggestion that TROP2 could be a therapeutic target for various carcinomas. Our results suggest that TROP2 expression is higher in advanced tumors and these results need to be supported by larger studies.

Trop2: Jack of All Trades, Master of None

Trophoblast cell surface antigen 2 (Trop2) is a widely expressed glycoprotein and an epithelial cell adhesion molecule (EpCAM) family member. Although initially identified as a transmembrane protein, other subcellular localizations and processed forms were described. Its congenital mutations cause a gelatinous drop-like corneal dystrophy, a disease characterized by loss of barrier function in corneal epithelial cells. Trop2 is considered a stem cell marker and its expression associates with regenerative capacity in various tissues. Trop2 overexpression was described in tumors of different origins; however, functional studies revealed both oncogenic and tumor suppressor roles. Nevertheless, therapeutic potential of Trop2 was recognized and clinical studies with drug-antibody conjugates have been initiated in various cancer types. One of these agents, sacituzumab govitecan, has been recently granted an accelerated approval for therapy of metastatic triple-negative breast cancer. In this article, we review the current knowledge about the yet controversial function of Trop2 in homeostasis and pathology.

Sacituzumab govitecan, a novel, third-generation, antibody-drug conjugate (ADC) for cancer therapy

INTRODUCTION

We describe a new, third-generation of antibody-drug conjugates (ADCs) having a high drug payload against topoisomerase I, important for DNA function, and targeting selective tumor antigens, predominantly TROP-2.

AREAS COVERED

The historical development of ADCs is reviewed before presenting the current line of improved, third-generation ADCs targeting topoisomerase I, thus affecting DNA and causing double-stranded DNA breaks. Emphasis is given to explaining why sacituzumab govitecan represents a paradigm change in ADCs by achieving a high therapeutic index due to its novel target, TROP-2, an internalizing antigen/antibody, proprietary linker chemistry, and high drug payload, resulting in a high tumor concentration of the drug given in repeated doses with acceptable tolerability, particularly evidencing a lower percentage of 'late' diarrhea than its prodrug, irinotecan. PubMed was used for the primary search conducted.

EXPERT OPINION

The properties and clinical results of third-generation ADCs, based on sacituzumab govitecan, are discussed, including prospects for future applications, particularly combination therapies with PARP inhibitors and immune checkpoint inhibitors. Since one topoisomerase I ADC has just received regulatory approval for HER2⁺ breast cancer, and sacituzumab govitecan is under FDA review for accelerated approval in the therapy of triple-negative breast cancer, the prospects for these novel ADCs are discussed.

MAGE-A1 in lung adenocarcinoma as a promising target of chimeric antigen receptor T cells

Background

Cancer/testis antigens (CTAs) are a special type of tumor antigen and are believed to act as potential targets for cancer immunotherapy.

Methods

In this study, we first screened a rational CTA MAGE-A1 for lung adenocarcinoma (LUAD) and explored the detailed characteristics of MAGE-A1 in LUAD development through a series of phenotypic experiments. Then, we developed a novel MAGE-A1-CAR-T cell (mCART) using lentiviral vector based on our previous MAGE-A1-scFv. The anti-tumor effects of this mCART were finally investigated in vitro and in vivo.

Results

The results showed striking malignant behaviors of MAGE-A1 in LUAD development, which further validated the rationality of MAGE-A1 as an appropriate target for LUAD treatment. Then, the innovative mCART was successfully constructed, and mCART displayed encouraging tumor-inhibitory efficacy in LUAD cells and xenografts.

Conclusions

Taken together, our data suggest that MAGE-A1 is a promising candidate marker for LUAD therapy and the MAGE-A1-specific CAR-T cell immunotherapy may be an effective strategy for the treatment of MAGE-A1-positive LUAD.

TROP2 increases growth and metastasis of human oral squamous cell carcinoma through activation of the PI3K/Akt signaling pathway

Most malignant neoplasms of the oral cavity are oral squamous cell carcinoma (OSCC), which is a type of highly malignant tumor with a propensity for forming distant metastases. Trophoblast cell surface antigen 2 (TROP2) is a transmembrane protein that is overexpressed in several types of tumor cells, although its role and regulatory mechanism in OSCC have not been determined. The aim of the present study was to examine the effects of TROP2 in human OSCC cell lines. The present study demonstrated that TROP2 protein expression was upregulated in OSCC cell lines. Transfection of short hairpin RNA (shRNA) targeting TROP2 (sh‑TROP2) reduced cell proliferation, migration and invasion of OSCC cell lines, whereas overexpression of TROP2 increased proliferation, migration and invasion. sh‑TROP2 transfection in OSCC cell lines inhibited tumor growth in OSCC mouse models. Furthermore, TROP2 expression activated the phosphoinositide 3‑kinase (PI3K)/Akt signaling pathway in human OSCC cells. These results suggest that TROP2 induces cell growth, migration and invasion through activation of the PI3K/Akt signaling pathway in OSCC cells.

A fully chimeric IgG antibody for ROR1 suppresses ovarian cancer growth in vitro and in vivo

BACKGROUND

Over-expression of Receptor-tyrosine-kinase-like Orphan Receptor 1 (ROR1) in cancer cells has been reported in the context of several tumors (including ovarian cancer) and is associated with poor prognosis. The aim of this study was to construct a fully chimeric anti-ROR1 IgG antibody (ROR1-IgG) and investigate its antitumor activity against ovarian cancer cells, bothin vitro and in vivo.

METHODS

A fully chimeric anti-ROR1 IgG antibody (ROR1-IgG) eukaryotic expression vector was constructed and ROR1-IgG antibody was expressed in CHO cells. The characteristics of ROR1-IgG were investigated by ELISA, SPR, Western blotting, FACS and fluorescence staining analyses. CCK8 and wound healing assays were performed to determine inhibition and migration capacity of ovarian cancer cells after treatment with ROR1-IgGin vitro. Further, the antitumor activity of ROR1-IgG was assessed in vivo using tumor-mice xenograft model.

RESULTS

The results showed that ROR1-IgG could specifically bind to ROR1-positive cells (HO8910 and A2780) with a high affinity. Functional studies revealed that ROR1-IgG inhibited the malignant behavior of ROR1-positive cells (HO8910 and A2780) in a time- and dose-dependent manner. These effects were not observed in ROR1-negative lose386 cells. The tumor inhibition rates following treatment with low, medium, and high concentrations of ROR1-IgG were approximately 47.72%, 53.79%, and 60.51%, respectively. In addition, the expression of Bcl-2 was obviously reduced while that of Bax was distinctly elevated in xenografts.

CONCLUSIONS

Collectively, our findings suggest that ROR1-IgG may be a novel therapeutic agent for patients with ROR1-positive ovarian cancer.

Antibody-drug conjugates targeting TROP-2 and incorporating SN-38: A case study of anti-TROP-2 sacituzumab govitecan

Antibody-drug conjugates (ADCs) that exploit the active metabolite SN-38, which is derived from the popular anticancer drug, irinotecan (a camptothecin that inhibits the nuclear topoisomerase I enzyme, inducing double-stranded DNA breaks during the mitotic S-phase of affected cells), represent a substantial advance in the ADC field. SN-38 has been conjugated to a humanized antibody against trophoblast cell surface antigen 2 (TROP-2), which is involved in cancer signaling pathways and has increased expression by many cancer cell types, yielding the ADC sacituzumab govitecan. By conjugating a higher number of SN-38 molecules to the immunoglobulin (drug-to-antibody ratio = 7-8:1), and giving higher (10 mg/kg) and repeated therapy cycles (Days 1 and 8 of 21-day cycles), enhanced drug uptake by the targeted cancer cells is achieved. Based on a unique conjugation method, the lactone ring of the SN-38 molecule is stabilized and the molecule is protected from glucuronidation, a process that contributes to the untoward late diarrhea experienced with irinotecan. Finally, while the ADC is internalized, the use of a moderately stable linker permits release of SN-38 in an acidic environment of the tumor cell and its microenvironment, contributing to a bystander effect on neighboring cancer cells. Here, we discuss the development of sacituzumab govitecan and clinical results obtained using it for the management of patients with advanced, refractive breast, lung, and urinary bladder cancers. Sacituzumab govitecan, which is undergoing accelerated approval review by the US Food and Drug Administration while also being studied in Phase 3 clinical studies, was granted Breakthrough Therapy status from the FDA for advanced, refractory, metastatic triple-negative breast cancer patients.

SPARC correlates with unfavorable outcome and promotes tumor growth in lung squamous cell carcinoma

Secreted protein acidic and rich in cysteine (SPARC) plays a crucial role in the malignant progression of a number of human cancers. However, the roles of SPARC in lung squamous cell carcinoma (LSCC) remain elusive. In this present study, we first detected SPARC expression and investigated the relationship between SPARC expression and the clinicopathological attributes of LSCC patients. Then we constructed SPARC-overexpression model in LSCC cell line to explore the characteristics of SPARC in LSCC development both in vitro and in vivo. The data demonstrated a remarkably higher level of SPARC in LSCC tissues than in corresponding non-cancerous tissues and elevated SPARC expression was significantly correlated with poor outcome in LSCC patients. Moreover, a serial of phenotypic experiments indicated that SPARC overexpression substantially facilitated the growth and inhibited the apoptosis in LSCC cells and xenografts. Taken together, our results suggest that SPARC is a novel prognostic marker for LSCC prognosis and SPARC significantly promotes LSCC tumorigenesis. Targeting SPARC may provide a novel therapeutic strategy for LSCC management.

ROR1 associates unfavorable prognosis and promotes lymphoma growth in DLBCL by affecting PI3K/Akt/mTOR signaling pathway

The receptor-tyrosine-kinase (RTK)-like orphan receptor 1 (ROR1) is a transmembrane glycoprotein regarded as a tumor-associated antigen. ROR1 plays an important role in cancer development, but the detailed function of ROR1 in diffuse large B-cell lymphoma (DLBCL) remains unclear. In this study, we first detected ROR1 expression and evaluated the relationship between ROR1 expression and the clinicopathological characteristics of DLBCL patients. Next we employed shRNA-mediated knockdown of ROR1 in DLBCL cell line to explore the characteristics of ROR1 in DLBCL development both in vitro and in vivo. The results showed a significantly higher level of ROR1 in DLBCL tissues than in lymphatic hyperplasia tissues. High ROR1 expression was correlated with unfavorable prognosis in DLBCL patients. Furthermore, ROR1 knockdown inhibited the growth and induced the apoptosis in DLBCL cells and xenografts. In addition, shROR1 inhibited activation of the PI3K/Akt/mTOR signaling pathway, both in vitro and in vivo. Taken together, our results suggest that ROR1 is a novel prognostic marker for DLBCL survival and ROR1 significantly promotes DLBCL tumorigenesis by regulating the PI3K/Akt/mTOR signaling pathway. Targeting ROR1 may provide a promising strategy for DLBCL treatment. © 2019 BioFactors, 45(3):416-426, 2019.

A novel human monoclonal Trop2-IgG antibody inhibits ovarian cancer growth in vitro and in vivo

Trop2 is a tumor-related antigen closely related to the development of a variety of tumors and has been identified as a promising target for cancer immunotherapy. In this study, a Trop2-IgG antibody was constructed by a eukaryotic expression system based on our previously constructed Trop2-Fab antibody. SDS-PAGE, cell ELISA, affinity assays, fluorescence staining and FACS analyses were performed to characterize Trop2-IgG. Then, CCK-8, wound healing, Transwell and annexin V-PI assays were employed to evaluate the tumor inhibitory effects of Trop2-IgG on OC in vitro, while tumor-bearing mice were constructed to examine the tumor inhibitory effects of Trop2-IgG on OC in vivo. Trop2-IgG was successfully constructed by a eukaryotic expression system and maintained recognition characteristics to Trop2 antigen. In vitro, Trop2-IgG could inhibited tumor cell growth, migration, and invasion compared to those of control cells and induced tumor cell apoptosis. In vivo, Trop2-IgG exerted critical tumor inhibitory effects in OC xenografts. Our data suggest that the use of Trop2-IgG provides a potential therapeutic strategy for the immunotherapy of Trop2-expressing OC.

Advanced microscopic evaluation of parallel type I and type II cell deaths induced by multi-functionalized gold nanocages in breast cancer

Despite aggressive surgical resections and combinatorial chemoradiations, certain highly malignant populations of tumor cells resurrect and metastasize. Mixed-grade cancer cells fail to respond to standard-of-care therapies by developing intrinsic chemoresistance and subsequently result in tumor relapse. Macroautophagy is a membrane trafficking process that underlies drug resistance and tumorigenesis in most breast cancers. Manipulating cellular homeostasis by a combinatorial nanotherapeutic model, one can evaluate the crosstalk between type I and type II cell death and decipher the fate of cancer therapy. Here, we present a multi-strategic approach in cancer targeting to mitigate the autophagic flux with subcellular toxicity via lysosome permeation, accompanied by mitochondrial perturbation and apoptosis. In this way, a nanoformulation is developed with a unique blend of a lysosomotropic agent, an immunomodulating sulfated-polysaccharide, an adjuvant chemotherapeutic agent, and a monoclonal antibody as a broad-spectrum complex for combinatorial nanotherapy of all breast cancers. To the best of our knowledge, this manuscript illustrates for the first time the applications of advanced microscopic techniques such as electron tomography, three-dimensional rendering and segmentation of subcellular interactions, and fate of the multifunctional therapeutic gold nanocages specifically targeted toward breast cancer cells.

FLOT1 promotes tumor development, induces epithelial-mesenchymal transition, and modulates the cell cycle by regulating the Erk/Akt signaling pathway in lung adenocarcinoma

Background

FLOT1 is a scaffolding protein of lipid rafts that is believed to be involved in numerous cellular processes. However, few studies have explored the function of FLOT1 in the development of lung adenocarcinoma (LUAD) and the underlying mechanisms of FLOT1 activity.

Methods

FLOT1 knockdown and overexpression models were constructed via lentivirus. Cell growth, invasion, migration, and apoptosis were detected to evaluate the role of FLOT1 in LUAD development. Epithelial–mesenchymal transition (EMT) and cell cycle regulatory markers were then examined. Finally, the influence of FLOT1 on the Erk/Akt signaling pathway was investigated.

Results

FLOT1 promoted cell growth, invasion, and migration and inhibited cell apoptosis. In addition, FLOT1 induced EMT and modulated the cell cycle by activating the Erk/Akt signaling pathway.

Conclusion

The findings indicate a significant role of FLOT1 in LUAD development. Targeting FLOT1 may be a potential therapeutic strategy for LUAD.

Targeting Trop-2 in solid tumors: future prospects

Trop-2 is a transmembrane glycoprotein that is upregulated in all cancer types independent of baseline levels of Trop-2 expression. Trop-2 is an ideal candidate for targeted therapeutics due to it being a transmembrane protein with an extracellular domain overexpressed on a wide variety of tumors as well as its upregulated expression relative to normal cells. As a result, several Trop-2-targeted therapeutics have recently been developed for clinical use, such as anti-Trop-2 antibodies and Trop-2-targeted antibody-drug conjugates (ADC). Subsequently, multiple early-phase clinical trials have demonstrated safety and clinical benefit of Trop-2-based ADCs across multiple tumor types. This includes clinical benefit and tolerability in tumor types with limited treatment options, such as triple-negative breast cancer, platinum-resistant urothelial cancer, and small-cell lung cancer. In this review, we elaborate on all clinical trials involving Trop-2.

TROP-2 exhibits tumor suppressive functions in cervical cancer by dual inhibition of IGF-1R and ALK signaling

OBJECTIVE

Inactivation of tumor suppressor genes promotes initiation and progression of cervical cancer. This study aims to investigate the tumor suppressive effects of TROP-2 in cervical cancer cells and to explain the underlying mechanisms.

METHODS

The tumor suppressive functions of TROP-2 in cervical cancer cells were examined by in vitro and in vivo tumorigenic functional assays. Downstream factors of TROP-2 were screened using Human Phospho-Receptor Tyrosine Kinase Array. Small molecule inhibitors were applied to HeLa cells to test the TROP-2 effects on the oncogenicity of IGF-1R and ALK. Protein interactions between TROP-2 and the ligands of IGF-1R and ALK were detected via immunoprecipitation assay and protein-protein affinity prediction.

RESULTS

In vitro and in vivo functional assays showed that overexpression of TROP-2 significantly inhibited the oncogenicity of cervical cancer cells; while knockdown of TROP-2 exhibited opposite effects. Human Phospho-Receptor Tyrosine Kinase Array showed that the activity of IGF-1R and ALK was stimulated by TROP-2 knockdown. Small molecule inhibitors AG1024 targeting IGF-1R and Crizotinib targeting ALK were treated to HeLa cells with and without TROP-2 overexpression, and results from cell viability and migration assays indicated that the oncogenicity of vector-transfected cells was repressed to a greater extent by the inhibition of either IGF-1R or ALK than that of the TROP-2-overexpressed cells. Immunoprecipitation assay and protein-protein affinity prediction suggested protein interactions between TROP-2 and the ligands of IGF-1R and ALK.

CONCLUSIONS

Collectively, our results support that TROP-2 exhibits tumor suppressor functions in cervical cancer through inhibiting the activity of IGF-1R and ALK.

High expression of NDRG3 associates with unfavorable overall survival in non-small cell lung cancer

BACKGROUND AND OBJECTIVE

N-myc downstream-regulated gene 3 (NDRG3) is one of the important members of the NDRG family which crucially take part in cell proliferation, differentiation and other biological processes.

METHODS

In this present study, western-blotting analysis was performed to evaluate NDRG3 expression in NSCLC cell lines. One-step quantitative reverse transcription-polymerase chain reaction (qPCR) with 16 fresh-frozen NSCLC samples and immunohistochemistry (IHC) analysis in 100 NSCLC cases were conducted to explore the relationship between NDRG3 expression and the clinicopathological characteristics of NSCLC.

RESULTS

NDRG3 expression levels were statistically higher in NSCLC cell lines and tissue samples, compared with that of in non-cancerous cell line and tissue samples (p< 0.05). The IHC data demonstrated that the NDRG3 expression was significantly correlated with pathological grade (p= 0.038), N (p= 0.020) and TNM stage (p= 0.002). Survival analysis and Kaplan-Meier curve indicated that NDRG3 expression (p= 0.002) and T (p= 0.047) were independently associated with the unfavorable overall survival of patients with NSCLC.

CONCLUSIONS

The data implied that NDRG3 expression may be identified as a new predictor in NSCLC prognosis.

TROP2 methylation and expression in tamoxifen-resistant breast cancer

BACKGROUND

The DNA methyltransferase 1 inhibitor, 5-Aza-2'-deoxycytidine (5-Aza-dC) is a potential treatment for breast cancer. However, not all breast tumors will respond similarly to treatment with 5-Aza-dC, and little is known regarding the response of hormone-resistant breast cancers to 5-Aza-dC.

METHODS

We demonstrate that 5-Aza-dC-treatment has a stronger effect on an estrogen receptor-negative, Tamoxifen-selected cell line, TMX2-28, than on the estrogen receptor-positive, MCF7, parental cell line. Using data obtained from the HM450 Methylation Bead Chip, pyrosequencing, and RT-qPCR, we identified a panel of genes that are silenced by promoter methylation in TMX2-28 and re-expressed after treatment with 5-Aza-dC.

RESULTS

One of the genes identified, tumor associated calcium signal transducer 2 (TACSTD2), is altered by DNA methylation, and there is evidence that in some cancers decreased expression may result in greater proliferation. Analysis of DNA methylation of TACSTD2 and protein expression of its product, trophoblast antigen protein 2 (TROP2), was extended to a panel of primary (n = 34) and recurrent (n = 34) breast tumors. Stratifying tumors by both recurrence and ER status showed no significant relationship between TROP2 levels and TACSTD2 methylation. Knocking down TACSTD2 expression in MCF7 increased proliferation however; re-expressing TACSTD2 in TMX2-28 did not inhibit proliferation, indicating that TACSTD2 re-expression alone was insufficient to explain the decreased proliferation observed after treatment with 5-Aza-dC.

CONCLUSIONS

These results illustrate the complexity of the TROP2 signaling network. However, TROP2 may be a valid therapeutic target for some cancers. Further studies are needed to identify biomarkers that indicate how TROP2 signaling affects tumor growth and whether targeting TROP2 would be beneficial to the patient.

The emergence of trophoblast cell-surface antigen 2 (TROP-2) as a novel cancer target

TROP-2 is a glycoprotein first described as a surface marker of trophoblast cells, but subsequently shown to be increased in many solid cancers, with lower expression in certain normal tissues. It regulates cancer growth, invasion and spread by several signaling pathways, and has a role in stem cell biology and other diseases. This review summarizes TROP-2's properties, especially in cancer, and particularly its role as a target for antibody-drug conjugates (ADC) or immunotherapy. When the irinotecan metabolite, SN-38, is conjugated to a humanized anti-TROP-2 antibody (sacituzumab govitecan), it shows potent broad anticancer activity in human cancer xenografts and in patients with advanced triple-negative breast, non-small cell and small-cell lung, as well as urothelial cancers.

TROP2 promotes cell proliferation and migration in osteosarcoma through PI3K/AKT signaling

Human trophoblast cell surface antigen 2 (TROP2) has been noted to serve an important role in the proliferation and migration of various types of human cancers. However, the potential role and the molecular mechanisms of TROP2 in osteosarcoma (OS) remain largely unclear. In the present study, high expression of TROP2 in human OS tissues and cell lines was observed. Overexpression of TROP2 promoted the proliferation and migration of OS cell lines, while TROP2 knockdown markedly decreased cell growth and migration. Furthermore, it was revealed that TROP2 overexpression significantly activated the phosphoinositide 3‑kinase/protein kinase B (PI3K/AKT) signaling pathway. Collectively, these results suggested that TROP2 may promote OS cell proliferation and migration via PI3K/AKT signaling and may serve as a novel treatment target for OS.

The tumor-inhibitory effectiveness of a novel anti-Trop2 Fab conjugate in pancreatic cancer

Human trophoblastic cell surface antigen 2 (Trop2) has been reported to act oncogenically. In this study, one-step quantitative real-time polymerase chain reaction (qPCR) test and immunohistochemistry (IHC) analysis with were employed to evaluate the relationship between Trop2 expression and the clinicopathological features of patients with PC. Then a novel anti-Trop2 Fab antibody was conjugated with Doxorubicin (DOX) to form Trop2Fab-DOX, an antibody-drug conjugate. This Trop2Fab-DOX conjugate was characterized by cell ELISA and immunofluorescence assay. MTT and wound healing analyses were used to evaluate the inhibitory effect of Trop2Fab-DOX on PC cell growth in vitro, while xenograft nude mice model was established to examine the tumor-inhibitory effects of PC in vivo. High Trop2 expression was observed in PC tissues and Trop2 expression was associated with several malignant attributes of PC patients, including overall survival. Trop2Fab-DOX can bind to the Trop2-expressing PC cells and provide an improved releasing type of DOX. In addition, Trop2Fab-DOX inhibited the proliferation and suppressed the migration of PC cells in a dose-dependent manner in vitro, while inhibited the growth of PC xenografts in vivo. Trop2 is a specific marker for PC, and a novel Trop2Fab-DOX ADC has a potent antitumor activity

Prognostic role and clinical significance of trophoblast cell surface antigen 2 in various carcinomas

Introduction

Trophoblast cell surface antigen 2 (TROP2) has been linked to disease prognosis in various human cancers and plays a critical role in tumor development, progression, and metastasis. A number of relevant studies have been published on this topic. A meta-analysis of the latest literature to evaluate the value of TROP2 as a predictive prognosticator of cancer was performed.

Methods

Several online databases were searched, and relevant articles were retrieved. Overall and subcategory meta-analyses were performed, and results were collated.

Results

Twenty-seven articles, including 29 studies, were included, involving 4,852 cancer patients, and results showed that the above-baseline expression of TROP2 was significantly associated with poorer overall survival (OS) (pooled hazard ratio [HR]: 1.84, 95% confidence interval [CI]: 1.45–2.35), disease-free survival (DFS) (pooled HR: 2.77, 95% CI: 1.73–4.42), and progression-free survival (PFS) (pooled HR: 1.71, 95% CI: 1.25–2.35). The following clinical characteristics were also significantly linked with TROP2 overexpression: moderate/poor differentiation (pooled HR: 3.03, 95% CI: 1.99–4.63), distant metastasis (pooled HR: 2.46, 95% CI: 1.05–5.75), lymph node metastasis (pooled HR: 2.47, 95%: CI 1.72–3.56), and advanced TNM stage (pooled HR: 2.02, 95% CI: 1.38–2.95).

Conclusion

TROP2 overexpression was predictive of poor prognosis in human cancers and may be an independent prognostic predictive biomarker. Further studies should be performed to confirm the significance of TROP2 in clinical practice.

Recent Advances in ADAM17 Research: A Promising Target for Cancer and Inflammation

Since its discovery, ADAM17, also known as TNFα converting enzyme or TACE, is now known to process over 80 different substrates. Many of these substrates are mediators of cancer and inflammation. The field of ADAM metalloproteinases is at a crossroad with many of the new potential therapeutic agents for ADAM17 advancing into the clinic. Researchers have now developed potential drugs for ADAM17 that are selective and do not have the side effects which were seen in earlier chemical entities that targeted this enzyme. ADAM17 inhibitors have broad therapeutic potential, with properties ranging from tumor immunosurveillance and overcoming drug and radiation resistance in cancer, as treatments for cardiac hypertrophy and inflammatory conditions such as inflammatory bowel disease and rheumatoid arthritis. This review focuses on substrates and inhibitors identified more recently for ADAM17 and their role in cancer and inflammation.

Trop2 enhances invasion of thyroid cancer by inducing MMP2 through ERK and JNK pathways

Background

Mounting evidence has showed that Tumor-associated calcium signal transducer 2 (Trop2) is upregulated in various kinds of human cancers and plays important roles in tumorigenesis. However, the expression status and functional significance of Trop2 in thyroid cancer are largely unknown.

Methods

We first determined the expression of Trop2 by using RNAseqV2 data sets for thyroid cancer deposited on The Cancer Genome Atlas (TCGA) website. The expression of Trop2 was then confirmed by real-time reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry assays. Cell invasion and migration were assessed by conducting Transwell and wound healing assays. Furthermore, we explored the underlying mechanisms by using real-time RT-PCR, Western blot, zymography, and luciferase reporter assays.

Results

In this study, we demonstrated that the expression of Trop2 was significantly elevated in thyroid cancer and that its expression level was correlated with the tumor-node-metastasis (TNM) staging and N classification. Dysregulation of Trop2 altered the invasive capability of thyroid cancer cells. Further mechanistic study revealed that MMP2 expression was upregulated by Trop2. Moreover, we found that the effects of Trop2 were dependent on ERK and JNK pathways. The results from clinical specimens showed that Trop2 expression correlated with MMP2 expression in primary thyroid cancer.

Conclusion

The current study suggests that elevated expression of Trop2 may represent an important molecular hallmark that is biologically and clinically relevant to the progression of thyroid cancer.

High Eg5 expression predicts poor prognosis in breast cancer

Eg5 is a motor protein belonging to the kinesin-5 family and has been suggested to exert important function in tumors. In this study, we determined the mRNA and protein expression levels of Eg5 in cancerous and non-cancerous breast tissue by quantitative real-time polymerase chain reaction (qRT-PCR) and tissue microarray immunohistochemistry analysis (TMA-IHC) respectively. The results of 20 fresh-frozen BC samples demonstrated that Eg5 mRNA levels were significantly higher in BC tissues compared with corresponding non-cancerous tissue (p = 0.0009). TMA-IHC analysis in 127 BC tissues revealed that Eg5 expression obviously correlated with clinicopathologial parameters, including tumor grade (p = 0.004), ER status (p = 0.030), Ki67 status (p = 0.005), molecular classification (p = 0.026), N stage (p = 0.015), and TNM stage (p = 0.001). Kaplan-Meier survival curve indicated that high Eg5 expression (p = 0.012), Ki67 status (p = 0.014) and TNM stage (p = 0.026) were independent factors to predict poor prognosis for patients with breast cancer. Our data suggest that Eg5 is not only overexpressed in BC, it may be also served as a potential prognostic marker.

A neutralized human LMP1-IgG inhibits ENKTL growth by suppressing the JAK3/STAT3 signaling pathway

Latent membrane protein 1 (LMP1), which is associated with the development of different types of Epstein-Barr virus (EBV) related lymphoma, has been suggested to be an important oncoprotein. In this study, a human anti-LMP1 IgG antibody (LMP1-IgG) was constructed and characterized by ELISA, western blotting (WB), affinity and immunohistochemistry (IHC) analyses. CCK-8, MTT, apoptosis assays, antibody-dependent cell-mediated cytotoxicity (ADCC) and CDC (complement-dependent cytotoxicity) assays were performed to evaluate the inhibitory effects of LMP1-IgG on extranodal nasal-type natural killer (NK)/T-cell lymphoma (ENKTL). Then, the influence of LMP1-IgG on the JAK/STAT signaling pathway was investigated. The results showed that the successfully constructed LMP1-IgG inhibited proliferation, induced apoptosis, and activated ADCC and CDC of ENKTL in a concentration- and time- dependent manner. Moreover, phosphorylation of JAK3 and STAT3 was inhibited by LMP1-IgG. Our data indicate that LMP1-IgG may provide a novel and promising therapeutic strategy for the treatment of LMP1-positive ENKTL.

Knockdown of PKM2 and GLS1 expression can significantly reverse oxaliplatin-resistance in colorectal cancer cells

Clinical treatment for colorectal cancer (CRC) thus far encounters a huge challenge due to oxaliplatin-resistance. As crucial rate-limiting enzymes in aerobic glycolysis and glutaminolysis, pyruvate kinase M2 type (PKM2) and kidney-type glutaminase (GLS1) are proposed to carry important implications in colorectal carcinogenesis and drug-resistance. This study aimed to explore the possible association of oxaliplatin-resistance with aerobic glycolysis/glutaminolysis indexed by PKM2/GLS1 expression. PKM2 and GLS1 expression was quantified by polymerase chain reaction (PCR) and Western blot techniques in CRC cell lines. The abilities of cell formation, kinetics, migration, invasion, survival and apoptosis, as well as permeability glycoprotein (Pgp) expression were inspected before and after knocking-down PKM2/GLS1 expression. In addition, the influence of knocking-down PKM2/GLS1 expression was evaluated in vivo. Differentiated PKM2 and GLS1 expression in both THC8307 and THC8307/Oxa cell lines was identified. In the THC8307 cell line, PKM2 and GLS1 can accelerate malignant behaviors, increase oxaliplatin-resistance, upregulate Pgp expression, and inhibit cell apoptosis. Contrastingly in the THC8307/Oxa cell line, knockdown of PKM2/GLS1 expression can restrain malignant behaviors, reestablish oxaliplatin-sensitivity, downregulate Pgp expression, and induce cell apoptosis. In xenograft, knockdown of PKM2/GLS1 expression can significantly inhibit tumor growth, reduce Pgp expression, and increase tumor apoptosis. Taken together, the present findings enriched our knowledge by demonstrating a significant association of PKM2 and GLS1 with oxaliplatin-resistance in CRC. We further propose that knockdown of PKM2/GLS1 expression may constitute a novel therapeutic strategy toward effective treatment for CRC.