Novel Anti-TM4SF1 Antibody-Drug Conjugates with Activity against Tumor Cells and Tumor Vasculature

PLAU promotes growth and attenuates cisplatin chemosensitivity in ARID1A-depleted non-small cell lung cancer through interaction with TM4SF1

Loss of ARID1A, a subunit of the SWI/SNF chromatin remodeling complex, contributes to malignant progression in multiple cancers including non-small cell lung cancer (NSCLC). In the search for key genes mediating the aggressive phenotype caused by ARID1A loss, we analyzed 3 Gene Expression Omnibus (GEO) datasets that contain RNA sequencing data from ARID1A-depleted cancer cells. PLAU was identified as a common gene that was induced in different cancer cells upon ARID1A depletion. Overexpression of PLAU positively modulated NSCLC cell growth, colony formation, cisplatin resistance, and survival under serum deprivation. Moreover, enforced expression of PLAU enhanced tumorigenesis of NSCLC cells in nude mice. Mechanistically, PLAU interacted with TM4SF1 to promote the activation of Akt signaling. TM4SF1-overexpressing NSCLC cells resembled those with PLAU overepxression. Knockdown of TM4SF1 inhibited the growth and survival and increased cisplatin sensitivity in NSCLC cells. The interaction between PLAU and TM4SF1 led to the activation of Akt signaling that endowed ARID1A-depleted NSCLC cells with aggressive properties. In addition, treatment with anti-TM4SF1 neutralizing antibody reduced the growth, cisplatin resistance, and tumorigenesis of ARID1A-depleted NSCLC cells. Taken together, PLAU serves as a target gene of ARID1A and promotes NSCLC growth, survival, and cisplatin resistance by stabilizing TM4SF1. Targeting TM4SF1 may be a promising therapeutic strategy for ARID1A-mutated NSCLC.

A Cell Surface-Binding Antibody Atlas Nominates a MUC18-Directed Antibody-Drug Conjugate for Targeting Melanoma

Recent advances in targeted therapy and immunotherapy have substantially improved the treatment of melanoma. However, therapeutic strategies are still needed for unresponsive or treatment-relapsed patients with melanoma. To discover antibody-drug conjugate (ADC)-tractable cell surface targets for melanoma, we developed an atlas of melanoma cell surface-binding antibodies (pAb) using a proteome-scale antibody array platform. Target identification of pAbs led to development of melanoma cell killing ADCs against LGR6, TRPM1, ASAP1, and MUC18, among others. MUC18 was overexpressed in both tumor cells and tumor-infiltrating blood vessels across major melanoma subtypes, making it a potential dual-compartment and universal melanoma therapeutic target. AMT-253, an MUC18-directed ADC based on topoisomerase I inhibitor exatecan and a self-immolative T moiety, had a higher therapeutic index compared with its microtubule inhibitor-based counterpart and favorable pharmacokinetics and tolerability in monkeys. AMT-253 exhibited MUC18-specific cytotoxicity through DNA damage and apoptosis and a strong bystander killing effect, leading to potent antitumor activities against melanoma cell line and patient-derived xenograft models. Tumor vasculature targeting by a mouse MUC18-specific antibody-T1000-exatecan conjugate inhibited tumor growth in human melanoma xenografts. Combination therapy of AMT-253 with an antiangiogenic agent generated higher efficacy than single agent in a mucosal melanoma model. Beyond melanoma, AMT-253 was also efficacious in a wide range of MUC18-expressing solid tumors. Efficient target/antibody discovery in combination with the T moiety-exatecan linker-payload exemplified here may facilitate discovery of new ADC to improve cancer treatment.

SIGNIFICANCE

Discovery of melanoma-targeting antibodies using a proteome-scale array and use of a cutting-edge linker-payload system led to development of a MUC18-targeting antibody-exatecan conjugate with clinical potential for treating major melanoma subtypes.

Single-cell RNA sequencing reveals cancer stem-like cells and dynamics in tumor microenvironment during cholangiocarcinoma progression

Cholangiocarcinoma is a malignancy of the bile ducts that is driven by activities of cancer stem-like cells and characterized by a heterogeneous tumor microenvironment. To better understand the transcriptional profiles of cancer stem-like cells and dynamics in the tumor microenvironment during the progression of cholangiocarcinoma, we performed single-cell RNA analysis on cells collected from three different timepoints of tumorigenesis in a YAP/AKT mouse model. Bulk RNA sequencing data from TCGA (The Cancer Genome Atlas program) and ICGC cohorts were used to verify and support the finding. In vitro and in vivo experiments were performed to assess the stemness of cancer stem-like cells. We identified Tm4sf1high malignant cells as cancer stem-like cells. Across timepoints of cholangiocarcinoma formation in YAP/AKT mice, we found dynamic change in cancer stem-like cell/stromal/immune cell composition. Nevertheless, the dynamic interaction among cancer stem-like cells, immune cells, and stromal cells at different timepoints was elaborated. Collectively, these data serve as a useful resource for better understanding cancer stem-like cell and malignant cell heterogeneity, stromal cell remodeling, and immune cell reprogramming. It also sheds new light on transcriptomic dynamics during cholangiocarcinoma progression at single-cell resolution.

Construction of CAR-T cells targeting TM4SF1 and its anti-tumor capacity in ovarian cancer

Ovarian cancer (OC) is the most lethal gynecological malignancy with a 5-year survival rate of 49.1% on average. In clinical practice, cytoreduction and chemotherapy remain the conventional treatment for advanced OC. However, the overall prognosis remains poor, which urges oncologists to develop new treatments. Chimeric antigen receptor (CAR)-T therapy as a branch of immunotherapy had gained a success in treating hematological malignancies. TM4SF1, a potential biomarker in many tumors, was validated highly expressed in ovarian cancer. Here we constructed a 3^rd generation CAR-T agent targeting TM4SF1 to treat ovarian cancer. CAR-T cells showed a specific cytotoxicity against TM4SF1 positive tumor cell lines in vitro and repressed SKOV3-derived tumor growth in vivo. This is the first time reporting a CAR-T therapy targeting TM4SF1 in ovarian cancer. Our results suggested that TM4SF1 could be a very promising target in curing OC and showed the possibility of TM4SF1-based immunotherapy.

Three Members of Transmembrane-4-Superfamily, TM4SF1, TM4SF4, and TM4SF5, as Emerging Anticancer Molecular Targets against Cancer Phenotypes and Chemoresistance

There are six members of the transmembrane 4 superfamily (TM4SF) that have similar topology and sequence homology. Physiologically, they regulate tissue differentiation, signal transduction pathways, cellular activation, proliferation, motility, adhesion, and angiogenesis. Accumulating evidence has demonstrated, among six TM4SF members, the regulatory roles of transmembrane 4 L6 domain family members, particularly TM4SF1, TM4SF4, and TM4SF5, in cancer angiogenesis, progression, and chemoresistance. Hence, targeting derailed TM4SF for cancer therapy has become an emerging research area. As compared to others, this review aimed to present a focused insight and update on the biological roles of TM4SF1, TM4SF4, and TM4SF5 in the progression, metastasis, and chemoresistance of various cancers. Additionally, the mechanistic pathways, diagnostic and prognostic values, and the potential and efficacy of current anti-TM4SF antibody treatment were also deciphered. It also recommended the exploration of other interactive molecules to be implicated in cancer progression and chemoresistance, as well as potential therapeutic agents targeting TM4SF as future perspectives. Generally, these three TM4SF members interact with different integrins and receptors to significantly induce intracellular signaling and regulate the proliferation, migration, and invasion of cancer cells. Intriguingly, gene silencing or anti-TM4SF antibody could reverse their regulatory roles deciphered in different preclinical models. They also have prognostic and diagnostic value as their high expression was detected in clinical tissues and cells of various cancers. Hence, TM4SF1, TM4SF4, and TM4SF5 are promising therapeutic targets for different cancer types preclinically and deserve further investigation.

Ascendancy of unfolded protein response over glioblastoma: estimating progression, prognosis and survival

Glioblastoma (GBM) is presented with a poor prognosis. The endoplasmic reticulum stress (ERS) has been implicated as a major contributor to disease progression and chemoresistance in GBM. Triggering ERS by chemical agents or genetic modulations is identified as some of the reasons for regulating gene expression and the pathogenesis of GBM. ERS initiates unfolded protein response (UPR), an integrated system useful in restoring homeostasis or inducing apoptosis. Modulation of UPR might have positive outcomes in GBM treatment as UPR inducers have been shown to alter cell survival and migration. In the current review, we have utilized GSE7806, a publicly available dataset from Gene Expression Omnibus (GEO), to evaluate the genes expressed during 6.5 hr and 18 hr, which can be comparable to the early and late-onset of the disease. Subsequently, we have elucidated the prognosis and survival information whilst the expression of these genes in the GBM was noted in previous studies. This is the first of its kind review summarizing the most recent gene information correlating UPR and GBM.

MicroRNA-501-3p targeting TM4SF1 facilitates tumor-related behaviors of gastric cancer cells via EMT signaling pathway

BACKGROUND

Increasing evidence shows that Transmembrane 4 L6 family member 1(TM4SF1) exerts a critical role in mediating the progression of various tumors. Nevertheless, the exact mechanism of TM4SF1 in gastric cancer (GC) remains unclear.

METHODS

Bioinformatics analysis was utilized to analyze TM4SF1 expression in GC tissues. Also, MiRWalk and starBase databases were used to predict the upstream microRNAs which could regulate TM4SF1 expression. Gene set enrichment analysis (GSEA) for TM4SF1 was conducted to screen the potentially involved pathways. Dysregulation of microRNA-501-3p/TM4SF1 was implemented to investigate the regulatory roles of these genes in GC. qRT-PCR and western blot were employed to measure the expression changes of microRNA-501-3p, TM4SF1, and epithelial-mesenchymal transition (EMT) signaling pathway-associated proteins. CCK-8, colony formation, and transwell assays were introduced to examine the biological functions of GC cell lines.

RESULTS

TM4SF1 presented a significantly low level in mRNA and protein in GC cells. MicroRNA-501-3p could target TM4SF1 and reduce its expression. Cell function experiments revealed that microRNA-501-3p facilitated cell proliferation, migration, and invasion, while inhibiting cell apoptosis in GC by targeting TM4SF1. EMT-associated proteins were altered by changing microRNA-501-3p/TM4SF1 axis.

CONCLUSION

MicroRNA-501-3p regulated EMT signaling pathway by down-regulating TM4SF1 expression and therefore facilitated the malignant progression of GC, which may provide a new potential therapeutic target for the treatment of GC patients.

Polymer Nanoparticles and Nanomotors Modified by DNA/RNA Aptamers and Antibodies in Targeted Therapy of Cancer

Polymer nanoparticles and nano/micromotors are novel nanostructures that are of increased interest especially in the diagnosis and therapy of cancer. These structures are modified by antibodies or nucleic acid aptamers and can recognize the cancer markers at the membrane of the cancer cells or in the intracellular side. They can serve as a cargo for targeted transport of drugs or nucleic acids in chemo- immuno- or gene therapy. The various mechanisms, such as enzyme, ultrasound, magnetic, electrical, or light, served as a driving force for nano/micromotors, allowing their transport into the cells. This review is focused on the recent achievements in the development of polymer nanoparticles and nano/micromotors modified by antibodies and nucleic acid aptamers. The methods of preparation of polymer nanoparticles, their structure and properties are provided together with those for synthesis and the application of nano/micromotors. The various mechanisms of the driving of nano/micromotors such as chemical, light, ultrasound, electric and magnetic fields are explained. The targeting drug delivery is based on the modification of nanostructures by receptors such as nucleic acid aptamers and antibodies. Special focus is therefore on the method of selection aptamers for recognition cancer markers as well as on the comparison of the properties of nucleic acid aptamers and antibodies. The methods of immobilization of aptamers at the nanoparticles and nano/micromotors are provided. Examples of applications of polymer nanoparticles and nano/micromotors in targeted delivery and in controlled drug release are presented. The future perspectives of biomimetic nanostructures in personalized nanomedicine are also discussed.

The Resurgence of Antibody Drug Conjugates in Cancer Therapeutics: Novel Targets and Payloads

Antibody drug conjugates (ADCs) are an emerging class of therapeutics that consist of a cytotoxic agent linked covalently to an antibody, which is directed toward a specific cell surface target expressed by tumor cells and/or the microenvironment. ADCs leverage the specificity of the antibody such that it functions as a carrier to deliver the cytotoxic payload into the tumor. Four parameters are considered critical for this class of complex engineered therapeutics: target selection, antibody, cytotoxic payload, as well as conjugation and linker technology. The development of this class of drugs has proven more complex than expected. Several challenges have arisen, including a lack of true tumor antigen specificity, early release of the cytotoxic payload into the bloodstream due to linker instability, and low potency of the payload, resulting in either greater toxicity or lack of improved efficacy compared with unconjugated cytotoxics. The approval of trastuzumab emtansine in 2013 for HER2-positive breast cancer served as a proof of concept that ADCs have therapeutic application in solid tumors. Two novel ADCs have recently been approved: trastuzumab deruxtecan for HER2-positive breast cancer and enfortumab vedotin for locally advanced or metastatic urothelial cancer. Trastuzumab deruxtecan is distinguished by a unique biochemical structure with a novel cytotoxic payload, deruxtecan-a highly potent, topoisomerase I inhibitor. Enfortumab vedotin is directed toward nectin-4 and represents an example of successful and strategic target selection. This review focuses on the concepts underlying the choice of suitable targets and novel payloads, discusses specific examples of ADCs in preclinical and clinical development, and provides future directions related to this unique class of therapeutics.

A Polypeptide of Tumor-Associated Antigen L6 with Intrinsic Adjuvant Activity Enhances Antitumor Immunity

Peptide vaccines are safe, and aim to elicit and expand tumor-specific immunity so as to eradicate tumors. However, achieving strong and long-lasting anti-tumor immunity with peptide vaccines for the antigen-specific treatment of cancer is challenging, in part because their efficacy depends on strong adjuvants or immunomodulators. We approached this problem by conjugating an epitope-based cancer vaccine with a lipidated sequence (an immunomodulator) to elicit a strong immune response. Lipidated and non-lipidated polyepitope proteins were generated that contained the universal T helper cell epitope (pan-DR), B cell epitopes, and the extended loop sequence of extracellular domain 2 of tumor-associated antigen L6 (TAL6). We show that the lipidated polyepitope cancer vaccine can activate bone marrow-derived dendritic cells, and trigger effective antigen-specific antibody and T helper cell responses, more effectively than the non-lipidated vaccine. Moreover, potent T cell immune responses were elicited in mice inoculated with the lipidated polyepitope cancer vaccine, providing protective antitumor immunity in mice bearing TAL6 tumors. Our study demonstrates that a lipidated polyepitope cancer vaccine could be employed to generate potent anti-tumor immune responses, including humoral and cellular immunity, which could be beneficial in the treatment of TAL6⁺ cancer.

Targeting Strategies for Tissue-Specific Drug Delivery

Off-target effects of systemically administered drugs have been a major hurdle in designing therapies with desired efficacy and acceptable toxicity. Developing targeting strategies to enable site-specific drug delivery holds promise in reducing off-target effects, decreasing unwanted toxicities, and thereby enhancing a drug's therapeutic efficacy. Over the past three decades, a large body of literature has focused on understanding the biological barriers that hinder tissue-specific drug delivery and strategies to overcome them. These efforts have led to several targeting strategies that modulate drug delivery in both the preclinical and clinical settings, including small molecule-, nucleic acid-, peptide-, antibody-, and cell-based strategies. Here, we discuss key advances and emerging concepts for tissue-specific drug delivery approaches and their clinical translation.

Role of Transmembrane 4 L Six Family 1 in the Development and Progression of Cancer

Transmembrane 4 L six family 1 (TM4SF1) is a protein with four transmembrane domains that belongs to the transmembrane 4 L six family members (TM4SFs). Structurally, TM4SF1 consists of four transmembrane domains (TM1–4), N- and C-terminal intracellular domains, two extracellular domains, a smaller domain between TM1 and TM2, and a larger domain between TM3 and TM4. Within the cell, TM4SF1 is located at the cell surface where it transmits extracellular signals into the cytoplasm. TM4SF1 interacts with tetraspanins, integrin, receptor tyrosine kinases, and other proteins to form tetraspanin-enriched microdomains. This interaction affects the pro-migratory activity of the cells, and thus it plays important roles in the development and progression of cancer. TM4SF1 has been shown to be overexpressed in many malignant tumors, including gliomas; malignant melanomas; and liver, prostate, breast, pancreatic, bladder, colon, lung, gastric, ovarian, and thyroid cancers. TM4SF1 promotes the migration and invasion of cancer cells by inducing epithelial-mesenchymal transition, self-renewal ability, tumor angiogenesis, invadopodia formation, and regulating the related signaling pathway. TM4SF1 is an independent prognostic indicator and biomarker in several cancers. It also promotes drug resistance, which is a major cause of therapeutic failure. These characteristics make TM4SF1 an attractive target for antibody-based immunotherapy. Here, we review the many functions of TM4SF1 in malignant tumors, with the aim to understand the interaction between its expression and the biological behaviors of cancer and to supply a basis for exploring new therapeutic targets.

Lost miR-141 and upregulated TM4SF1 expressions associate with poor prognosis of pancreatic cancer: regulation of EMT and angiogenesis by miR-141 and TM4SF1 via AKT

Background: Transmembrane-4-L-six-family-1 (TM4SF1) functions to regulate cell growth and mobility and TM4SF1 expression was upregulated in pancreatic cancer. This study further investigated the role of TM4SF1 in regulating pancreatic cancer epithelial-mesenchymal transition (EMT) and angiogenesis and the underlying molecular events.Methods: Tissue specimens were collected from 90 pancreatic cancer patients for immunohistochemical and qRT-PCR analysis of miR-141 and TM4SF1 levels, respectively. Pancreatic cancer cell lines were used for in vitro assays, while nude mice were used for the in vivo assay.Results: TM4SF1 expression was upregulated, whereas miR-141 expression was lost in pancreatic cancer tissues, both of which was associated with advanced clinicopathological features and poor survival of pancreatic cancer patients. Furthermore, miR-141 was able to target and reduce TM4SF1 expression in pancreatic cancer cells and miR-141 expression inhibited pancreatic cancer cell EMT in vitro and Matrigel plug angiogenesis and lung metastasis in nude mice. At the gene level, miR-141 directly targeted and reduced TM4SF1 expression and in turn induced E-cadherin expression and reduced VEGF-A expression by suppressing activation of the AKT signaling pathway.Conclusions: This study demonstrated that upregulated TM4SF1 and lost miR-141 expression were associated with advanced clinicopathological features and poor survival of pancreatic cancer patients. Lost miR-141 expression but induced TM4SF1 expression altered expression of VEGF-A and E-cadherin and promoted pancreatic cancer cell EMT and angiogenesis via the AKT signaling pathway, suggesting that targeting of miR-141 and TM4SF1 may be a potential therapeutic strategy to control pancreatic cancer.

Phage display screening of therapeutic peptide for cancer targeting and therapy

Recently, phage display technology has been announced as the recipient of Nobel Prize in Chemistry 2018. Phage display technique allows high affinity target-binding peptides to be selected from a complex mixture pool of billions of displayed peptides on phage in a combinatorial library and could be further enriched through the biopanning process; proving to be a powerful technique in the screening of peptide with high affinity and selectivity. In this review, we will first discuss the modifications in phage display techniques used to isolate various cancer-specific ligands by in situ, in vitro, in vivo, and ex vivo screening methods. We will then discuss prominent examples of solid tumor targeting-peptides; namely peptide targeting tumor vasculature, tumor microenvironment (TME) and over-expressed receptors on cancer cells identified through phage display screening. We will also discuss the current challenges and future outlook for targeting peptide-based therapeutics in the clinics.

TM4SF1 is a potential target for anti-invasion and metastasis in ovarian cancer

BACKGROUND

Patients with ovarian cancer commonly have a poor prognosis, owing to its invasiveness and distant metastasis. Studies have found TM4SF1 participates in regulating tumor cell invasion and migration. Therefore, it is expected to become a target for anti-invasion and metastasis in ovarian cancer.

METHODS

The expression of TM4SF1 in normal ovarian epithelial tissues, benign ovarian tumor tissues, primary foci of epithelial ovarian cancer and the matched lymph mode metastatic foci was detected using immunohistochemistry to analyze its association with prognosis. The expression of TM4SF1 in HO8910PM, SKOV3 was inhibited using RNAi, and the growth, proliferation, migration, invasion abilities of HO8910PM and SKOV3 cells and the growth of xenograft tumors in nude mice were examined.

RESULTS

(1) The positive expression rate of TM4SF1 protein in epithelial ovarian cancer tissues (90.90%) was higher than that in benign ovarian tumor tissues (65.22%) and normal ovarian epithelial tissues (31.25%), and both differences were significant (P < 0.05). The expression of TM4SF1 protein was positive in all metastatic lymph node foci and matched primary foci (100%). (2) The level of TM4SF1 protein expression was positively correlated with the International Federation of Gynecology and Obstetrics (FIGO) stage and histological grade. However, The positive TM4SF1 protein expression was not an independent factor of prognosis (P > 0.05). (3) Silencing TM4SF1 expression did not affect growth, proliferation, or cell cycle distribution but inhibited the migration and invasion abilities of HO8910PM and SKOV3 cells. Silencing TM4SF1 expression inhibited the growth of xenograft tumors in nude mice.

CONCLUSION

TM4SF1 is a potential target for anti-invasion and metastasis in ovarian cancer.

Application of Immuno-PET in Antibody-Drug Conjugate Development

Targeted therapies hold great promise for cancer treatment and may exhibit even greater efficacy when combined with patient selection tools. The clinical impact of identifying likely responders includes reducing the number of unnecessary and ineffective therapies as well as more accurately determining drug effects. Positron emission tomography (PET) imaging using zirconium-89 radiolabeled monoclonal antibodies (mAbs), also referred to as zirconium-89 (⁸⁹Zr)-immuno-PET, provides a potential biomarker to measure target expression and verify optimal delivery of targeted agents to tumors. Antibody-drug conjugates (ADCs) combine the high affinity and specificity of mAbs with the potency of cytotoxic drugs to target tumor-expressing antigen and destroy cancer cells. Thus, ⁸⁹Zr-immuno-PET of whole-body biodistribution, pharmacokinetics, and tumor targeting of antibodies and ADCs to predict toxicity and efficacy could help guide individualized treatment. Here, we review how ⁸⁹Zr-immuno-PET is being used as a companion diagnostic with the development of ADCs. Furthermore, we discuss how ⁸⁹Zr-immuno-PET may be utilized in future clinical trials as an adjunct tool with novel ADCs to select cancer patients who have the greatest potential to benefit from treatment and improve ADC dosing regimens.

Clinical significance of TM4SF1 as a tumor suppressor gene in gastric cancer

Transmembrane‐4‐L‐six‐family member‐1 (TM4SF1), a tumor‐associated antigen, is overexpressed in most epithelial cell carcinomas and a potential target for antibody‐mediated therapy. However, the role of TM4SF1 in gastric cancer has not been elucidated. The aim of this study was to investigate the clinical significance of TM4SF1 expression in gastric carcinoma (GC) tissues using 152 GC tissue samples and matched adjacent nontumor tissue samples analyzed by immunohistochemistry, and 13 fresh GC tissue samples analyzed by Western blotting. The results showed that TM4SF1 was heterogeneously expressed in normal gastric mucosa, with a high expression rate in fundus mucosa. Higher levels and strong expression rate of TM4SF1 were associated with GC tissues of higher‐grade differentiation. TM4SF1 levels were lower in gastric cancer tissues than gastric noncancerous tissues. Expression of TM4SF1 was not correlated with USP10 (P = 0.157), S100A12 (P = 0.479), p53 (P = 0.249), or Ki67 (P = 0.166) in GC. The expression of TM4SF1 was significantly and negatively correlated with depth of invasion (P = 0.031), nodal metastasis (P = 0.042), TNM stage (P = 0.030), and Lauren classification (P = 0.026). There was no significant correlation between TM4SF1 expression and age, gender, tumor size, or distant metastasis (P > 0.05). The expression of TM4SF1 was associated with well overall survival (P = 0.0164). The 5‐year survival rate for patients with GC showing TM4SF1 positive was 58.82% (10/17), and the median survival time was 78 months, higher than that (12.90%, 12/93) of patients who were TM4SF1 negative, whose median survival time was 62 months. These data suggested that low expression of TM4SF1 is associated with carcinogenesis and development, tumor progression and invasion of gastric cancer, and poor overall survival of patients with GC. TM4SF1 is a tumor suppressor for GC and a novel prognostic marker for patients with GC.

microRNA-520f inhibits hepatocellular carcinoma cell proliferation and invasion by targeting TM4SF1

microRNAs (miRNAs) are reported to play crucial roles in tumorigenesis. Dysregulation of miR-520f has been implicated to be involved in several cancer progressions. However, the biological functions of miR520f in hepatocellular carcinoma (HCC) remain unclear. Thus, the molecular mechanism underlying miR-520f on HCC development was investigated in this study. Here, we found that miR-520f was remarkably down-regulated in human HCC samples and cell lines compared to paired normal tissues and cell lines as detected by qRT-PCR. Furthermore, the deregulated miR-520f was strongly associated with larger tumor size, advanced TNM stage, and metastasis in HCC patients. Functional investigations revealed that overexpression of miR-520f significantly suppressed cell proliferation, invasion and migration, caused cell cycle arrested at G0/G1 phase, and promoted cell apoptosis in HCC cells according to MTT, colony formation, transwell, and flow cytometry assays, respectively, whereas, downregulation of miR-520f exhibited inverse effects. Transmembrane-4 L-Six family member-1 (TM4SF1) was identified as a direct target of miR-520f, and an inverse relationship was found between miR-520f and TM4SF1 mRNA levels in HCC specimens. Rescue experiments suggested that restoration of TM4SF1 partially abolished miR-520f-meidated cell proliferation and invasion inhibition in HCC cells through regulating P13K/AKT and p38 MAPK signaling pathways. In conclusion, these data indicated that miR-520f acted as tumor suppressor in HCC proliferation and invasion by targeting TM4SF1, which might provide potential therapeutic evidence for HCC patients.

The state-of-play and future of antibody therapeutics

It has been over four decades since the development of monoclonal antibodies (mAbs) using a hybridoma cell line was first reported. Since then more than thirty therapeutic antibodies have been marketed, mostly as oncology, autoimmune and inflammatory therapeutics. While antibodies are very efficient, their cost-effectiveness has always been discussed owing to their high costs, accumulating to more than one billion dollars from preclinical development through to market approval. Because of this, therapeutic antibodies are inaccessible to some patients in both developed and developing countries. The growing interest in biosimilar antibodies as affordable versions of therapeutic antibodies may provide alternative treatment options as well potentially decreasing costs. As certain markets begin to capitalize on this opportunity, regulatory authorities continue to refine the requirements for demonstrating quality, efficacy and safety of biosimilar compared to originator products. In addition to biosimilars, innovations in antibody engineering are providing the opportunity to design biobetter antibodies with improved properties to maximize efficacy. Enhancing effector function, antibody drug conjugates (ADC) or targeting multiple disease pathways via multi-specific antibodies are being explored. The manufacturing process of antibodies is also moving forward with advancements relating to host cell production and purification processes. Studies into the physical and chemical degradation pathways of antibodies are contributing to the design of more stable proteins guided by computational tools. Moreover, the delivery and pharmacokinetics of antibody-based therapeutics are improving as optimized formulations are pursued through the implementation of recent innovations in the field.

TM4SF1 regulates apoptosis, cell cycle and ROS metabolism via the PPARγ-SIRT1 feedback loop in human bladder cancer cells

Transmembrane-4-L-Six-Family-1 (TM4SF1) is a member of the L6 family and functions as a signal transducer to regulate cell development, growth and motility. Here we show that TM4SF1 is strongly upregulated in human muscle invasive bladder cancer (MIBC) tissues, corroborating the bioinformatical results of transcriptome analysis. Moreover, tissue microarray (TMA) shows significant correlations (p < 0.05) between high expression of TM4SF1 and T stage, TNM stage, lymph node metastasis status and survival rate of MIBC patients, indicating a positive association between TM4SF1 expression and poorer prognosis. Furthermore, in vitro and in vivo studies indicate that the proliferation of human bladder cancer (BCa) cells is significantly suppressed by knockdown of TM4SF1 (p < 0.05). Functionally, the reduction of TM4SF1 could induce cell cycle arrest and apoptosis possibly via the upregulation of reactive oxygen species (ROS) in BCa cells. In addition, these observations could be recovered by treatment with GW9662 (antagonist of PPARγ) and resveratrol (activator of SIRT1). Taken together, our results suggest that high expression of TM4SF1 predicts poor prognosis of MIBC.

MicroRNA-30a-5p (miR-30a) regulates cell motility and EMT by directly targeting oncogenic TM4SF1 in colorectal cancer

PURPOSE

Colorectal cancer (CRC) is one of the leading causes of cancer death worldwide, and many oncogenes and tumor suppressor genes are involved in CRC. MicroRNAs (miRNAs) are small non-coding RNAs that can negatively regulate gene expression. Previous studies have revealed that miRNAs regulate the development and progression of many cancers. In this study, we investigated the role of microRNA-30a-5p (miR-30a) in CRC and its unknown mechanisms.

METHODS

qRT-PCR was used to detect miR-30a and TM4SF1 mRNA expression in CRC specimens and cell lines. CRC cell migration and invasion were assessed after transfection with miR-30a or TM4SF1 using wound healing and trans-well migration and invasion assays. Transmembrane-4-L-six-family protein (TM4SF1) was validated as a target of miR-30a in CRC through luciferase reporter assay and bioinformatics algorithms. Moreover, two EMT regulators, E-cadherin and VEGF, were also identified using Western blotting and immunohistochemistry.

RESULTS

We found that miR-30a was down-regulated in CRC tumor tissues and cell lines, and miR-30a was inversely associated with advanced stage and lymph node metastatic status compared with normal tissues. miR-30a decreased migration and invasion in CRC cell lines, and miR-30a overexpression not only down-regulated TM4SF1 mRNA and protein expression, but also inhibited the expression of VEGF and enhanced expression of E-cadherin. We also showed that TM4SF1 was up-regulated in CRC tumor specimens compared with adjacent normal tissues, and TM4SF1 expression was significantly associated with advanced stage and lymph node status compared with adjacent normal tissues.

CONCLUSIONS

These results suggest that miR-30a is an important regulator of TM4SF1, VEGF, and E-cadherin for CRC lymph node metastasis, a potential new therapeutic target in CRC.

Eradication of Tumors through Simultaneous Ablation of CD276/B7-H3-Positive Tumor Cells and Tumor Vasculature

Targeting the tumor vasculature with antibody-drug conjugates (ADCs) is a promising anti-cancer strategy that in order to be realized must overcome several obstacles, including identification of suitable targets and optimal warheads. Here, we demonstrate that the cell-surface protein CD276/B7-H3 is broadly overexpressed by multiple tumor types on both cancer cells and tumor-infiltrating blood vessels, making it a potentially ideal dual-compartment therapeutic target. In preclinical studies CD276 ADCs armed with a conventional MMAE warhead destroyed CD276-positive cancer cells, but were ineffective against tumor vasculature. In contrast, pyrrolobenzodiazepine-conjugated CD276 ADCs killed both cancer cells and tumor vasculature, eradicating large established tumors and metastases, and improving long-term overall survival. CD276-targeted dual-compartment ablation could aid in the development of highly selective broad-acting anti-cancer therapies.

Strategies and challenges for the next generation of antibody-drug conjugates

Antibody-drug conjugates (ADCs) are one of the fastest growing classes of oncology therapeutics. After half a century of research, the approvals of brentuximab vedotin (in 2011) and trastuzumab emtansine (in 2013) have paved the way for ongoing clinical trials that are evaluating more than 60 further ADC candidates. The limited success of first-generation ADCs (developed in the early 2000s) informed strategies to bring second-generation ADCs to the market, which have higher levels of cytotoxic drug conjugation, lower levels of naked antibodies and more-stable linkers between the drug and the antibody. Furthermore, lessons learned during the past decade are now being used in the development of third-generation ADCs. In this Review, we discuss strategies to select the best target antigens as well as suitable cytotoxic drugs; the design of optimized linkers; the discovery of bioorthogonal conjugation chemistries; and toxicity issues. The selection and engineering of antibodies for site-specific drug conjugation, which will result in higher homogeneity and increased stability, as well as the quest for new conjugation chemistries and mechanisms of action, are priorities in ADC research.

TM4SF1 Promotes Gemcitabine Resistance of Pancreatic Cancer In Vitro and In Vivo

Background

TM4SF1 is overexpressed in pancreatic ductal adenocarcinoma (PDAC) and affects the development of this cancer. Also, multidrug resistance (MDR) is generally associated with tumor chemoresistance in pancreatic cancer. However, the correlation between TM4SF1 and MDR remains unknown. This research aims to investigate the effect of TM4SF1 on gemcitabine resistance in PDAC and explore the possible molecular mechanism between TM4SF1 and MDR.

Methods

The expression of TM4SF1 was evaluated in pancreatic cancer cell lines and human pancreatic duct epithelial (HPDE) cell lines by quantitative RT-PCR. TM4SF1 siRNA transfection was carried out using Hiperfect transfection reagent to knock down TM4SF1. The transcripts were analyzed by quantitative RT-PCR, RT-PCR and western blotting for further study. The cell proliferation and apoptosis were obtained to investigate the sensitivity to gemcitabine of pancreatic cancer cells after silencing TM4SF1 in vitro. We demonstrated that cell signaling of TM4SF1 mediated chemoresistance in cancer cells by assessing the expression of multidrug resistance (MDR) genes using quantitative RT-PCR. In vivo, we used orthotopic pancreatic tumor models to investigate the effect of proliferation after silencing TM4SF1 by a lentivirus-mediated shRNA in MIA PaCa-2 cell lines.

Results

The mRNA expression of TM4SF1 was higher in seven pancreatic cancer cell lines than in HPDE cell lines. In three gemcitabine-sensitive cell lines (L3.6pl, BxPC-3, SU86.86), the expression of TM4SF1 was lower than that in four gemcitabine-resistant cell lines (MIA PaCa-2, PANC-1, Hs766T, AsPC-1). We evaluated that TM4SF1 was a putative target for gemcitabine resistance in pancreatic cancer cells. Using AsPC-1, MIA PaCa-2 and PANC-1, we investigated that TM4SF1 silencing affected cell proliferation and increased the percentages of cell apoptosis mediated by treatment with gemcitabine compared with cells which were treated with negative control. This resistance was associated with the expression of multidrug resistance genes including ABCB1 and ABCC1. In vivo, silencing of TM4SF1 in MIA PaCa-2 cell lines increased the effectiveness of gemcitabine-based treatment in orthotopic pancreatic tumor models evaluated using noninvasive bioluminescent imaging.

Conclusion

These findings suggest that TM4SF1 is a surface membrane antigen that is highly expressed in pancreatic cancer cells and increases the chemoresistance to gemcitabine. Thus, TM4SF1 may be a promising target to overcome the chemoresistance of pancreatic cancer.

Intracellular distribution of TM4SF1 and internalization of TM4SF1-antibody complex in vascular endothelial cells

Transmembrane-4 L-six family member-1 (TM4SF1) is a small plasma membrane-associated glycoprotein that is highly and selectively expressed on the plasma membranes of tumor cells, cultured endothelial cells, and, in vivo, on tumor-associated endothelium. Immunofluorescence microscopy also demonstrated TM4SF1 in cytoplasm and, tentatively, within nuclei. With monoclonal antibody 8G4, and the finer resolution afforded by immuno-nanogold transmission electron microscopy, we now demonstrate TM4SF1 in uncoated cytoplasmic vesicles, nuclear pores and nucleoplasm. Because of its prominent surface location on tumor cells and tumor-associated endothelium, TM4SF1 has potential as a dual therapeutic target using an antibody drug conjugate (ADC) approach. For ADC to be successful, antibodies reacting with cell surface antigens must be internalized for delivery of associated toxins to intracellular targets. We now report that 8G4 is efficiently taken up into cultured endothelial cells by uncoated vesicles in a dynamin-dependent, clathrin-independent manner. It is then transported along microtubules through the cytoplasm and passes through nuclear pores into the nucleus. These findings validate TM4SF1 as an attractive candidate for cancer therapy with antibody-bound toxins that have the capacity to react with either cytoplasmic or nuclear targets in tumor cells or tumor-associated vascular endothelium.