Immune Checkpoint Inhibitors in Cancer Therapy-How to Overcome Drug Resistance?

Immune checkpoint inhibitors (ICIs), antagonists used to remove tumor suppression of immune cells, have been widely used in clinical settings. Their high antitumor effect makes them crucial for treating cancer after surgery, radiotherapy, chemotherapy, and targeted therapy. However, with the advent of ICIs and their use by a large number of patients, more clinical data have gradually shown that some cancer patients still have resistance to ICI treatment, which makes some patients unable to benefit from their antitumor effect. Therefore, it is vital to understand their antitumor and drug resistance mechanisms. In this review, we focused on the antitumor action sites and mechanisms of different types of ICIs. We then listed the main possible mechanisms of ICI resistance based on recent studies. Finally, we proposed current and future solutions for the resistance of ICIs, providing theoretical support for improving their clinical antitumor effect.

Long non-coding RNAs as targets for immunosuppressive drug teriflunomide in anti-cancer potential for hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is the most common form of liver cancer. Because of the relatively chemotherapy-refractory nature of HCC and significant potential poor hepatic reserve, chemotherapy has not been used consistently in the treatment of HCC. Effective new drugs for HCC are urgently needed. Teriflunomide, which was approved for the treatment of relapsing forms of multiple sclerosis (MS), has been identified as a potential antineoplastic drug. Long noncoding RNAs (lncRNAs) are a novel class of RNA molecules defined as transcripts longer than 200 nucleotides that lack protein coding potential. In this study, we investigated the ability of teriflunomide to act as an antineoplastic drug by examining the effects of teriflunomide treatment on HCC cells. Teriflunomide strongly inhibited the proliferation of HCC cells, induced cell apoptosis and induced cell accumulation in S phases of the cell cycle. LncRNA and mRNA expression profiles of HCC cells treated with teriflunomide compared with controls were performed by using microarray analysis. For comparison, the differentially expressed mRNAs were annotated by using gene ontology (GO) and pathway analyses. The microarray revealed that 2085 lncRNAs and 1561 mRNAs differed in the cells treated with teriflunomide compared with controls. Several GO terms including protein folding, mitochondrial outer membrane, transmembrane receptor protein phosphatase activity, negative regulation of cellular biosynthetic process, DNA packaging complex, and receptor signaling protein activity were enriched in gene lists, suggesting a potential correlation with the action mechanism of teriflunomide. Pathway analysis then demonstrated that JAK-STAT signaling pathway may play important roles in the cell apoptosis induced by teriflunomide. Co-expression network analysis indicated that a number of lncRNAs and mRNAs were included in the co-expression network, and p34710_v4 is the lncRNA with highest degree. Then the mRNAs associated with those differentially expressed lncRNAs were also annotated by using gene ontology (GO) and pathway analyses. The pathway analyses shows that teriflunomide significantly inhibited cell proliferation and promoted cell apoptosis partly by participating in Wnt signaling pathways. These findings suggest that teriflunomide could be a potential drug for chemotherapy and molecularly targeted therapies of HCC.

Design, synthesis, and evaluation of a series of novel phenylpropanoic acid derivatives agonists for the FFA1.

Free fatty acid 1 (FFA1/GPR40) has attracted extensive attention as a novel target for the treatment of type 2 diabetes for its role in the enhancement of insulin secretion with glucose dependency. Aiming to develop novel potent FFA1 agonists, a new series of phenylpropionic acid derivatives were designed and synthesized on the basis of the modification of chemical cement of TAK-875, AMG-837, and LY2881835. Among them, most promising compounds 7, 14, and 15 were obtained with EC50 values of 82, 79, and 88 nM, exhibiting a powerful agonistic activity compared to TAK-875 (95.1 nM). During Oral glucose tolerance test in normal mice, compound 7, 14, and 15 had significant glucose-lowering effect at the dose of 50 mg/kg. Furthermore, compound 15 (50 mg/kg) also significantly improved in glucose tolerance in type 2 diabetic mice. Herein, we reported the discovery and optimization of a series of potent FFA1 agonists. The discovery supported further exploration surrounding this scaffold.

Treatment of hypertension by increasing impaired endothelial TRPV4-KCa2.3 interaction.

The currently available antihypertensive agents have undesirable adverse effects due to systemically altering target activity including receptors, channels, and enzymes. These effects, such as loss of potassium ions induced by diuretics, bronchospasm by beta-blockers, constipation by Ca2+ channel blockers, and dry cough by ACEI, lead to non-compliance with therapies (Moser, 1990). Here, based on new hypertension mechanisms, we explored a new antihypertensive approach. We report that transient receptor potential vanilloid 4 (TRPV4) interacts with Ca2+-activated potassium channel 3 (KCa2.3) in endothelial cells (ECs) from small resistance arteries of normotensive humans, while ECs from hypertensive patients show a reduced interaction between TRPV4 and KCa2.3. Murine hypertension models, induced by high-salt diet, N(G)-nitro-l-arginine intake, or angiotensin II delivery, showed decreased TRPV4-KCa2.3 interaction in ECs. Perturbation of the TRPV4-KCa2.3 interaction in mouse ECs by overexpressing full-length KCa2.3 or defective KCa2.3 had hypotensive or hypertensive effects, respectively. Next, we developed a small-molecule drug, JNc-440, which showed affinity for both TRPV4 and KCa2.3. JNc-440 significantly strengthened the TRPV4-KCa2.3 interaction in ECs, enhanced vasodilation, and exerted antihypertensive effects in mice. Importantly, JNc-440 specifically targeted the impaired TRPV4-KCa2.3 interaction in ECs but did not systemically activate TRPV4 and KCa2.3. Together, our data highlight the importance of impaired endothelial TRPV4-KCa2.3 coupling in the progression of hypertension and suggest a novel approach for antihypertensive drug development.

Teriflunomide, an immunomodulatory drug, exerts anticancer activity in triple negative breast cancer cells.

Triple-negative breast cancer (TNBC) is defined as a group of primary breast cancers lacking expression of estrogen, progesterone, and human epidermal growth factor receptor-2 (HER-2) receptors, characterized by higher relapse rate and lower survival compared with other subtypes. Due to lack of identified targets and molecular heterogeneity, conventional chemotherapy is the only available option for treatment of TNBC, but non-discordant positive therapeutic efficacy could not be achieved. Here, we demonstrated that these TNBC cells were sensitive to teriflunomide, which was a well-known immunomodulatory drug for treatment of relapsing multiple sclerosis (MS). Potent anti-cancer effects in TNBC in vitro, including proliferation inhibition, cell cycle delay, cell apoptosis, and suppression of cell motility and invasiveness, could be achieved with this agent. Of note, we showed that multiple signals involved in TNBC proliferation, survival, migratory, and invasive potential were under regulation by teriflunomide. Among them, we identified down-regulation of growth factor receptors to abolish growth maintenance, suppression of c-Myc, and cyclin D1 to contribute to its anti-proliferative effect, modulation of components of cell cycle to induce S-phase arrest, degradation of Bcl-xL, and up-regulation of BAX via activation of MAPK pathway to induce apoptosis, and inhibition of epithelial-mesenchymal transition (EMT) process, matrix metalloproteinase-9 (MMP9) expression, and inactivation of Src/FAK to reduce TNBC migration and invasion. The results identified teriflunomide may be of therapeutic benefit for the more aggressive and difficult-to-treat breast cancer subtype, indicating the use of teriflunomide for clinical trials for treatment of TNBC patients.