Human antigen R and drug resistance in tumors Summary The human embryonic lethal abnormal visual protein, HuR, belongs to the Hu family of RNA-binding proteins. Over the past two decades, HuR has been extensively associated with multiple biological characteristics of tumors, including tumor development and progression, angiogenesis, invasion, migration and prognosis, since this protein regulates the stability of cancer-associated target mRNAs due to its posttranscriptional regulatory mechanisms. A recent investigation of the multiple functions of HuR has provided emerging evidence of its role in drug resistance in various tumors. Herein, we demonstrate the roles of HuR proteins in the development of drug resistance, examine their involvement in various mechanisms, including apoptosis, the ABC transporter family, the cell cycle and the DNA damage response, and provide insight into ongoing studies for developing therapeutic strategies aimed at targeting this molecule in tumor cells.

The cellular effects of novel triazine nitrogen mustards in glioblastoma LBC3, LN-18 and LN-229 cell lines Summary 1,3,5-triazine is an important heterocyclic skeleton for mono, two or three 2-chloroethylamine groups. The study presented here provides novel information on cellular effects of 1,3,5-triazine with mono, two or three 2-chloroethylamine groups in glioblastoma LBC3, LN-18 and LN-229 cell lines. In our study, the most cytotoxic effect was observed in 1,3,5-triazine with three 2-chloroethylamine groups (12f compound). It has been demonstrated that 12f induce time- and dose-dependent cytotoxicity in all investigated glioma cell lines. Apart from that in glioblastoma cells, treated with 12f compound, we noticed strong induction of apoptosis. In conclusion, this research provides novel information concerning cellular effects of apoptosis in LBC3, LN-18 and LN-229 cell lines. Moreover, we suggest that 12f compound may be a candidate for further evaluation as an effective chemotherapeutic agent for human glioblastoma cells.

The drug lag and associated factors for orphan anticancer drugs in Japan compared to the United States Summary The approval of orphan anticancer drugs in Japan has increased to meet high social demand. Drug lag, namely the approval lag of new drugs, is recognized as a social issue in Japan. We investigated the approval lag and its components, submission lag and review-time lag, between Japan and the United States (US) to reveal whether an approval lag still exists, and to identify potential factors that may contribute to reducing the approval lag. Anticancer drugs approved in Japan between April 2004 and November 2017 were investigated using publicly available information. Results showed that the median approval lag of orphan anticancer drugs in 2016–2017 was 727.0 days (interquartile range, IQR, 310.0–1054.3). The approval lag was significantly correlated with the submission lag (correlation coefficient = 1.00, P < 0.001) but not with the review-time lag (correlation coefficient = −0.16, P = 0.22). The submission lag was significantly longer for orphan anticancer drugs than non-orphan drugs (median, 712.5 days [IQR, 186.0–1448.3] vs. 387.0 days [92.8–1096.0], P = 0.023). External collaboration in drug development was associated with a longer submission lag (coefficient = 762.1, P = 0.017), while breakthrough therapy designation in the US was associated with a shorter submission lag (coefficient = −832.8, P = 0.035). In conclusion, we revealed that an approval lag for orphan anticancer drugs still existed in 2016–2017. A submission lag for orphan anticancer drugs was the main component affecting the approval lag, and was longer than that for non-orphan drugs. External collaboration in drug development may be a potential factor in reducing the submission lag for orphan anticancer drugs.

The availability of drug by liposomal drug delivery Summary Lately, the usefulness of liposomal drug delivery systems has been debated. To better understand the underlying pharmacokinetics of the targeted drug delivery by liposomes, individual encapsulated and non-encapsulated drug concentrations in blood, tumor, liver, spleen and kidneys were quantified after i.v. administration of liposomal prednisolone phosphate in mice. Kinetic analysis shows that the tumor influx of encapsulated drug is not dominant compared to the uptake by the other tissues. Further, from a quantitative point of view, the availability of non-encapsulated drug in the tumor tissue after liposomal delivery is not pronounced as compared to the other tissues studied. However, drug release in the tumor seems more extended than in the other tissues and the non-encapsulated drug concentration decreases more slowly in the tumor than in the liver and spleen. The spleen shows a high affinity for the uptake of encapsulated drug as well as the release of drug from the liposomes. Subsequently, released drug in the spleen, and possibly also in other tissues, is probably quickly redistributed towards the blood and other tissues. This also impairs the drug delivery effect of the liposomes. In contrast to the released drug in the central circulation, liver and spleen, the released drug concentration in the tumor remains at a fairly constant level likely due to the extended release kinetics from the liposomes. These extended release characteristics in the tumor most probably contribute to the beneficial effect. Nevertheless, it should be noted that larger released drug concentrations are formed in healthy tissues.

MiR-181a, a new regulator of TGF-β signaling, can promote cell migration and proliferation in gastric cancer Summary Transforming growth factor-beta (TGF-β) signaling pathway plays pivotal roles in various types of cancer. TGF-β receptor 2 (TGFβR2) contains a kinase domain that phosphorylates and activates the downstream of the TGF-β signaling pathway. Our previous microarray analysis revealed marked changes in miR-181a expression in gastric cancers, and the bioinformatics analysis suggested that miR-181a negatively regulated TGFβR2. In order to verify the effect of miR-181a on TGFβR2 and clarify the influence of miR-181a on the migration and proliferation of gastric cancer, studies in gastric cancer cell lines and xenograft mouse models were carried out. We found that a reduced expression of TGFβR2 and an increased expression miR-181a in gastric cancer tissues compared to adjacent noncancerous tissues. A luciferase reporter assay confirmed that TGFβR2 was a target of miR-181a. In addition, we found that miR-181a mimics, which increased the level of miR-181a, downregulated the expression of TGFβR2 in the gastric cancer cell line SGC-7901. Moreover, both the overexpression of miR-181a and the downregulation of TGFβR2 promoted the migration and proliferation of SGC-7901 cells. Conversely, SGC-7901 cell migration and proliferation were inhibited by the downregulation of miR-181a and the overexpression of TGFβR2. Furthermore, the increased expression of miR-181a and the decreased expression of TGFβR2 also enhanced the tumor growth in mice bearing gastric cancer. Our results herein indicated that miR-181a promoted the migration and proliferation of gastric cancer cells by downregulating TGFβR2 at the posttranscriptional level. The present study suggests that miR-181a is a novel negative regulator of TGFβR2 in the TGF-β signaling pathway and thus represents a potential new therapeutic target for gastric cancer.

Nifuroxazide induces apoptosis, inhibits cell migration and invasion in osteosarcoma Summary Osteosarcoma is the most common primary malignancy of bone and characterized by an appendicular primary tumor with a high rate of metastasis to the lungs. Unfortunately, there is no effective strategy to treat osteosarcoma in current clinical practice. In this study, the anticancer effects and potential mechanisms of nifuroxazide, an oral nitrofuran antibiotic, on two osteosarcoma cell lines were investigated. The results of the antiproliferative activity in vitro showed that nifuroxazide inhibited cell proliferation of UMR106 and MG63 cells in a dose- and time-dependent manner. Interestingly, nifuroxazide showed low toxicity to non-tumor cells (HEK 293 T). In addition, ROS-mitochondrial mediated apoptosis was observed after treatment of nifuroxazide. Moreover, nifuroxazide could significantly inhibit osteosarcoma cells migration and invasion via p-Stat3, MMP-2 and MMP-9 mediated signaling pathway. Taken together, our results suggested that nifuroxazide could be a promising agent for osteosarcoma treatment by inhibiting cell proliferation, inducing cell apoptosis and impairing cell migration and invasion.

The bispecific anti-CD3 × anti-CD155 antibody mediates T cell immunotherapy for human prostate cancer Summary Expression of CD155 differs between tumor and normal tissues, and high expression of this molecule can promote tumor metastasis. Here, we investigate whether CD155 can serve as a target for T cell-mediated immunotherapy of human prostate cancer. We first demonstrate that prostate cancer cells, including PC-3, PC-3 M, and LNCAP cells, express CD155 at high levels. Next, the specific cytotoxic activity of activated T cells (ATCs) armed with a novel anti-CD3 × anti-CD155 bispecific antibody (CD155Bi-Ab) against tumor cells was evaluated by flow cytometry, lactate dehydrogenase assay (LDH), and ELISA. In contrast to unarmed ATCs, an increase in the cytotoxic activity of CD155Bi-armed ATCs against tumor cells was observed at an effector/target (E/T) ratio of 5:1. Moreover, CD155Bi-armed ATCs secreted more IFN-γ, TNF-α, and IL-2 and expressed higher levels of the activation marker CD69 than did unarmed ATCs. As CD155 Bi-Ab enhances the ability of ATCs to kill prostate cancer cells, CD155 is an effective target for cytotoxic T cells in human prostate cancer therapy.

Bispecific anti-CD3 x anti-B7-H3 antibody mediates T cell cytotoxic ability to human melanoma in vitro and in vivo Summary Inhibition of the B7-H3 immune checkpoint is reported to limit the tumor growth of B7-H3+ tumors. In this study, we demonstrated B7-H3 expression in human melanoma cells, including a primary culture and several cell lines. Furthermore, we investigated whether B7-H3 could serve as a target for T cell-mediated immunotherapy against melanoma. The cytotoxic capacity of activated T cells (ATCs) armed with an anti-CD3 x anti-B7-H3 bispecific antibody (B7-H3Bi-Ab) to melanoma cells was measured using a bioluminescent signal through a luciferase reporter on tumor cells. In contrast to unarmed ATCs, B7-H3Bi-Ab-armed ATCs exhibited increased cytotoxicity against melanoma cells at effector/target ratios from 1:1 to 20:1. Moreover, B7-H3Bi-Ab-armed ATCs secreted more interferin-gamma (IFN-γ), accompanied by higher levels of activating marker CD69 and CD25 expression. Infusion of B7-H3Bi-Ab-armed ATCs suppressed melanoma growth in a xenograft mouse model. Taken together, our results indicate that B7-H3Bi-Ab-armed ATCs may be a promising approach to immunotherapy for melanoma patients.

A mediator of phosphorylated Smad2/3, evodiamine, in the reversion of TAF-induced EMT in normal colonic epithelial cells Summary Purpose Transdifferentiation exists within stromal cells in the tumour microenvironment. Transforming growth factor-β (TGF-β) secreted by tumour-associated fibroblasts (TAFs) affects the differentiation states of epithelial cells, including epithelial-mesenchymal transition (EMT). Evodiamine, a natural drug, can regulate differentiation. However, the specific effects and relative mechanisms of evodiamine remain unknown. Design We used four models to observe the influence of TAF-like CCD-18Co cells on the colon epithelial cell line HCoEpiC: the 3D- and 2D-mono-culture system, Transwell and direct co-culture model. Additionally, we established conditioned medium from CCD-18Co cells. The TGF-β pathway inhibitor LY364947 and evodiamine were added. Morphological changes and classical EMT markers were observed and detected using phase contrast microscopy and immunofluorescence. Cell migration was measured by the wound-healing assay. Western blotting was performed to detect the TGF-β/Smad signalling pathway. Results CCD-18Co cells induced EMT-like changes in the 2D- and 3D-cultured epithelial cell line HCoEpiC, accompanied by high expression of ZEB1 and Snail and the enhancement of migration. Moreover, CCD-18Co-derived conditioned medium caused dysfunction of TGF-β/Smad signalling in EMT. Evodiamine inhibited these EMT-like HCoEpiC and their migration. Additionally, evodiamine down-regulated the expression of ZEB1/Snail and up-regulated the expression of phosphorylated Smad2/3 (pSmad2/3). Evodiamine also increased the ratios of pSmad2/Smad2 and pSmad3/Smad3. Conclusion Based on our observations, evodiamine can reverse the TAF-induced EMT-like phenotype in colon epithelial cells, which may be associated with its mediation of phosphorylated Smad2 and Smad3 expression.

A phase I study of the antibody drug conjugate ASG-5ME, an SLC44A4-targeting antibody carrying auristatin E, in metastatic castration-resistant prostate cancer Summary Background Antibody drug conjugates (ADC) offer the potential of maximizing efficacy while minimizing systemic toxicity. ASG-5ME, an SLC44A4-targeting antibody carrying monomethyl auristatin E (MMAE), a microtubule-disrupting agent, was investigated in men with metastatic castration resistant prostate cancer. Methods The primary objective of this phase I study was to determine maximum tolerated dose (MTD) and recommended phase II dose. Secondary objectives were safety, antitumor activity, pharmacokinetic properties, immunogenicity, and the detection of SLC44A4 on circulating tumor cells. Patients (pts) were treated among 7 dose levels every 21 days. A dose expansion phase enrolled 20 additional pts. at the MTD. Results Twenty-six and 20 pts. were treated in dose escalation and dose expansion cohorts respectively. The MTD was 2.7 mg/kg. Dose-limiting toxicities occurred in 4 pts.: grade 3 fatigue (n = 1); grade 3 abdominal pain, diarrhea and fatigue (n = 1); grade 4 neutropenia and hyponatremia and grade 3 maculopapular rash, constipation and hypoxia (n = 1); grade 3 troponin elevation without cardiac sequelae (n = 1). Fatigue and diarrhea were the most prevalent adverse events (AEs) across all cycles. Two grade 5 AEs occurred in the dose expansion cohort, each after 1 dose: 1 pt. developed grade 3 hyperglycemia, renal insufficiency and leukopenia; 1 pt. developed grade 3 hyperglycemia complicated by bacteremia. Free MMAE levels did not accumulate with repeat dosing. Of evaluable pts., 52% had either stable disease or a partial response. Conclusions Further development of ASG-5ME is not being pursued due to its narrow therapeutic index. Some toxicities were potentially related to on-target effects on normal tissue expressing the SLC44A4 protein. However, other toxicities were consistent with studies of previous MMAE-containing ADCs. Unconjugated MMAE is a less likely etiology based on prior data.