Rewarding and reinforcing effects of two dissociative-based new psychoactive substances, deschloroketamine and diphenidine, in mice.

Dissociative-based new psychoactive substances (NPSs) are increasingly available through the Internet, and public health problems related to the recreational use of these substances have been increasing globally. Two such NPSs are deschloroketamine and diphenidine, which are primarily used recreationally as ketamine substitutes. However, there is little scientific evidence to describe the dependence liability of NPSs. This study aimed to evaluate the dependence liability of deschloroketamine and diphenidine via animal behavioral experiments. We evaluated the rewarding and reinforcing effects of these NPSs using the conditioned place preference (CPP) and the self-administration (SA) paradigms in mice. Psychomotor effects and behavioral features of these compounds were assessed by quantifying locomotor activity, stereotypic movements, and dopaminergic neurotransmission. Both deschloroketamine (10 mg/kg) and diphenidine (10-60 mg/kg) produced increased locomotor activation and stereotypy that were similar to the effects of ketamine (10 mg/kg). Both deschloroketamine (10 mg/kg) and diphenidine (10, 20 mg/kg) increased the animals' preference for the drug-paired compartment in the CPP testing. In the SA testing, deschloroketamine (1 mg/kg/infusion) increased the number of active lever presses and the number of infusions received, whereas diphenidine administration (1, 2 mg/kg/infusion) did not alter either of these. Furthermore, both deschloroketamine and diphenidine increased dopamine levels in PC-12 cells. Collectively, the data suggest that deschloroketamine may have both rewarding and reinforcing effects, whereas diphenidine only induced rewarding effect.

Intracellular KRAS-specific antibody enhances the anti-tumor efficacy of gemcitabine in pancreatic cancer by inducing endosomal escape.

KRAS mutation is associated with the progression and growth of pancreatic cancer and contributes to chemo-resistance, which poses a significant clinical challenge in pancreatic cancer. Here, we developed a RT22-ep59 antibody (Ab) that directly targets the intracellularly activated GTP-bound form of oncogenic KRAS mutants after it is internalized into cytosol by endocytosis through tumor-associated receptor of extracellular epithelial cell adhesion molecule (EpCAM) and investigated its synergistic anticancer effects in the presence of gemcitabine in pancreatic cancer. We first observed that RT22-ep59 specifically recognized tumor-associated EpCAM and reached the cytosol by endosomal escape. In addition, the anticancer effect of RT22-ep59 was observed in the high-EpCAM-expressing pancreatic cancer cells and gemcitabine-resistant pancreatic cancer cells, but it had little effect on the low-EpCAM-expressing pancreatic cancer cells. Additionally, co-treatment with RT22-ep59 and gemcitabine synergistically inhibited cell viability, migration, and invasion in 3D-cultures and exhibited synergistic anticancer activity by inhibiting the RAF/ERK or PI3K/AKT pathways in cells with high-EpCAM expression. In an orthotopic mouse model, combined administration of RT22-ep59 and gemcitabine significantly inhibited tumor growth. Furthermore, the co-treatment suppressed cancer metastasis by blocking EMT signaling in vitro and in vivo. Our results demonstrated that RT22-ep59 synergistically increased the antitumor activity of gemcitabine by inhibiting RAS signaling by specifically targeting KRAS. This indicates that co-treatment with RT22-ep59 and gemcitabine might be considered a potential therapeutic strategy for pancreatic cancer patients harboring KRAS mutation.

KRAS targeting antibody synergizes anti-cancer activity of gemcitabine against pancreatic cancer.

Pancreatic cancer exhibits an oncogenic KRAS mutation rate of ∼90%. Despite research and drug development efforts focused on KRAS, no targeted therapy has been clinically approved for the treatment of pancreatic cancer with KRAS mutation. Also, the efficacy of gemcitabine is poor due to rapidly acquired resistance. We developed RT11-i antibody, which directly targets the intracellularly activated GTP-bound form of oncogenic RAS mutants. Here, we investigated the combined effects of RT11-i and gemcitabine in vitro and in vivo, and the mechanism involved. RT11-i significantly sensitized pancreatic cancer cells to gemcitabine. Also, the co-treatment synergistically inhibited angiogenesis, migration, and invasion, and showed synergistic anticancer activity by inhibiting the RAF/MEK/ERK or PI3K/AKT pathways. Furthermore, co-treatment inhibited endothelial barrier disruption in tumor vessels, which is a critical step in vascular leakiness of metastasis, and improved vessel structural stability. Importantly, co-treatment significantly suppressed tumor growth in an orthotopic tumor model. Taken together, our findings show that RT11-i synergistically increased the antitumor activity of gemcitabine by inhibiting RAS downstream signaling, which suggests RT11-i and gemcitabine be viewed a potential combination treatment option for pancreatic cancer patients with KRAS mutation.

Melatonin Synergizes with Sorafenib to Suppress Pancreatic Cancer via Melatonin Receptor and PDGFR-ß/STAT3 Pathway.

BACKGROUND/AIMS: Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignant tumors with poor prognosis. Conventional chemotherapies including gemcitabine have failed owing to weak response and side effects. Hence novel treatment regimens are urgently needed to improve the therapeutic efficacy. In this study, we aimed to assess the anticancer activity of melatonin and sorafenib as a novel therapy against PDAC. METHODS: We used various apoptosis assay and PDAC xenograft model to assess anticancer effect in vitro and in vivo. We applied phospho-receptor tyrosine kinase (RTK) array and phospho-tyrosine kinase array to explore the mechanism of the combined therapy. Western blotting, proximity ligation assay, and immunoprecipitation assay were also performed for validation. RESULTS: Melatonin synergized with sorafenib to suppress the growth of PDAC both in vitro and in vivo. The effect was due to increased apoptosis rate of PDAC cells that was accompanied by mitochondria dysfunction. The enhanced anticancer efficacy by the co-treatment could be explained by blockade of PDGFR-ß/STAT3 signaling pathway and melatonin receptor (MT)-mediated STAT3. CONCLUSIONS: Melatonin reinforces the anticancer activity of sorafenib by downregulation of PDGFR-ß/STAT3 signaling pathway and melatonin receptor (MT)-mediated STAT3. The combination of the two agents might be a potential therapeutic strategy for treating PDAC.

A novel tropomyosin-related kinase A inhibitor, KK5101 to treat pancreatic cancer.

Tropomyosin-related kinase A (TrkA) plays important roles in tumor cell growth and survival signaling and contributes to chemo-resistance in pancreatic cancer. Therefore, we developed KK5101, a novel TrkA target inhibitor and assessed its anti-cancer effects and investigated underlying mechanism of action in pancreatic cancer. KK5101 was characterized to inhibit TrkA selectively and potently by protein binding assay. It effectively inhibited the growth and proliferation of pancreatic cancer cells. Also, KK5101 increased apoptosis with loss of mitochondrial membrane potential, as evidenced by increases of cytochrome c releases. It increased numbers of TUNEL-positive apoptotic cells, and cell death including early and late apoptosis by Annexin V assay. In addition, activation of the TrkA signaling cascades including p-AKT, p-MEK, and p-STAT3 were inhibited by KK5101 treatment in vitro, as well as ex vivo tumor spheroid models, resulting in potent induction of apoptosis. Importantly, KK5101 also significantly attenuated tumor growth of in vivo pancreatic cancer models. These findings indicate that KK5101 may exert antitumor effects by directly affecting cancer cell growth or survival via inhibition of TrkA signaling pathway. We therefore suggest that KK5101 is a novel therapeutic candidate for treating pancreatic cancer.

Tumor vessel normalization by the PI3K inhibitor HS-173 enhances drug delivery.

Tumor vessels are leaky and immature, which causes poor oxygen and nutrient supply to tumor vessels and results in cancer cell metastasis to distant organs. This instability of tumor blood vessels also makes it difficult for anticancer drugs to penetrate and reach tumors. Numerous tumor vessel normalization approaches have been investigated for improving drug delivery into tumors. In this study, we investigated whether phosphoinositide 3-kinase (PI3K) inhibitors are able to improve vascular structure and function over the prolonged period necessary to achieve effective vessel normalization. The PI3K inhibitors, HS-173 and BEZ235 potently suppressed tumor growth and hypoxia, and increased tumor apoptosis in animal models. PI3K inhibitors also induced a regular, flat monolayer of endothelial cells (ECs) in vessels, improving stability of vessel structure, and normalized tumor vessels by increasing vascular maturity, pericyte coverage, basement membrane thickness, and tight-junctions. These effects resulted in a decrease in tumor vessel tortuosity and vessel thinning, and improved vessel function and blood flow. The tumor vessel stabilization effect of the PI3K inhibitor HS-173 also decreased the number of metastatic lung nodules in vivo metastasis model. Furthermore, HS-173 improved the delivery of doxorubicin into the tumor region, enhancing its anticancer effects. Mechanistic studies suggested that PI3K inhibitor HS-173-induced vessel normalization reflected changes in endothelial Notch signaling. Taken together, our findings indicate that vessel normalization by PI3K inhibitors restrained tumor growth and metastasis while improving chemotherapy by enhancing drug delivery into the tumor, suggesting that HS-173 may have a therapeutic value as an enhancer or an anticancer drug.

Radiosensitization of the PI3K inhibitor HS-173 through reduction of DNA damage repair in pancreatic cancer.

Activation of PI3K/AKT pathway occurs frequently in tumors and is correlated with radioresistance. The PI3K/AKT pathway can be an important target for improvement of radiotherapy. Although adding of chemotherapy to radiation therapy regimen enhances survival in patients with locally advanced pancreatic cancer, more effective therapies for increasing radiosensitivity are urgently needed. In this study, we investigated whether the novel PI3K inhibitor HS-173 could attenuate radiation-induced up-regulation of DNA damage repair processes and assessed its efficacy as a radio- and chemo-sensitizer. Radiosensitizing effects of HS-173 were tested in human pancreatic cells using clonogenic survival and growth assays. Mechanisms underlying the effects of HS-173 and radiation were determined by assessing cell cycle and DNA damage- repair pathway components, including ataxia-telangiectasia mutated (ATM) and DNA-dependent protein kinase catalytic subunit (DNA-PKcs). The in vivo efficacy of HS-173 in cancer radiotherapy was evaluated using a human tumor xenograft model. HS-173 significantly increased the sensitivity of pancreatic cancer cells to radiation, an effect that was associated with G2/M cell cycle arrest. HS-173 also significantly attenuated DNA damage repair by potently inhibiting ATM and DNA-PKcs, the two major kinases that respond to radiation-induced DNA double-strand breaks (DSBs), resulting in sustained DNA damage. Moreover, the combination of HS-173 and radiation delayed tumor growth and impaired DNA repair in a pancreatic cancer xenograft model, reflecting enhanced radiosensitization. These results showed that HS-173 significantly improved radiotherapy by inhibiting the DNA damage-repair pathway in pancreatic cancer. We therefore suggest that HS-173 may be an effective radiosensitizer for pancreatic cancer.