JAK2 inhibitors improve RA combined with pulmonary fibrosis in rats by downregulating SMAD3 phosphorylation.

BACKGROUND: JAK inhibitors are well known for the treatment of rheumatoid arthritis (RA), but whether they can be used to treat pulmonary fibrosis, a common extra-articular disease of RA, remains to be clarified. METHODS: A jak2 inhibitor, CEP33779 (CEP), was administered to a rat model of RA-associated interstitial lung disease to observe the degree of improvement in both joint swelling and pulmonary fibrosis. HFL1 cells were stimulated with TGF-ß1 to observe the expression of p-JAK2. Then, different concentrations of related gene inhibitors (JAK2, TGFß-R1/2, and p-STAT3) or silencers (STAT3, JAK2) were administered to HFL1 cells, and the expression levels of related proteins were detected to explore the underlying mechanisms of action. RESULTS: CEP not only reduced the degree of joint swelling and inflammation in rats but also improved lung function, inhibited the pro-inflammatory factors IL-1ß and IL-6, reduced lung inflammation and collagen deposition, and alleviated lung fibrosis. CEP decreased the expression levels of TGFß-R2, p-SMAD, p-STAT3, and ECM proteins in rat lung tissues. TGF-ß1 induced HFL1 cells to highly express p-JAK2, with the most pronounced expression at 48 h. The levels of p-STAT3, p-SMAD3, and ECM-related proteins were significantly reduced after inhibition of either JAK2 or STAT3. CONCLUSION: JAK2 inhibitors may be an important and novel immunotherapeutic drug that can improve RA symptoms while also delaying or blocking the development of associated pulmonary fibrotic disease. The mechanism may be related to the downregulation of p-STAT3 protein via inhibition of the JAK2/STAT signaling pathway, which affects the phosphorylation of SMAD3.

CEP33779 ameliorates pulmonary fibrosis associated with rheumatoid arthritis via the cross-talk between JAK2 and TGF-β 1 signaling pathway / 中华风湿病学杂志

Objective:Rat model of RA complicated with pulmonary fibrosis were constructed to observe the degree of improvement of pulmonary fibrosis in RA rats by JAK2 inhibitor CEP33779 and the possible mechanisms.Methods:①The RA models were constructed by subcutaneous injection of 0.2 ml (1 mg/ml) of bovine type Ⅱ collagen into the tail of the rats on the day of modeling development (d0); intratracheal injection of 100 μl bleomycin (2.5 mg/kg) was used to induce pulmonary fibrosis model at d13. In vivo study: model rats were randomly divided into the normal group, pulmonary fibrosis group, pulmonary fibrosis CEP treatment group, RA complicated with pulmonary fibrosis group, and RA complicated pulmonary fibrosis CEP treatment group. Rats in the treatment group was given CEP (10 ml/kg) qd by gavage from d14 to week 4. The right hind foot of the rats was measured for joints swelling and the arthritis index score were measured, lung compliance (Cst) and lung specific gravity were measured. In addition, the pathological changes of the left lung were observed by HE and Masson staining, and the extracellular matrix level of the right lung was measured by protein immunoblotting (WB). ② In vitro study: TGF-β 1 (10 ng/ml) was applied to stimulate human embryonic lung fibroblasts (HFL1) for 24 h and 48h, and p-JAK2 expression was detected by immunofluorescence. After HFL1 inoculation of culture plates, the control group, TGF-β 1 stimulation group, TGF-β 1+ LY2109761 (TGFβ-R1/2 inhibitor group, 0.5 mmol/L and 2 mmol/L) group, TGF-β 1+CEP (0.1 mmol/L and 1.0 mmol/L) group were co-incubated for 48 h, and the expression levels of TGFβ-R2, α-SMA, JAK2, and Col 1 were measured by WB. Comparisons between multiple groups were made by Tukey′s test, and comparisons between the two groups were analyzed by independent t-test. Results:① In vivo study, compared with the control group (1.45±0.04), joint swelling was increased at d13 [(2.54±0.16) in RA+PF+Vehicle group, t=16.02, P<0.001], and the mean arthritis index score and toe volume were decreased 3 days after CEP treatment(d16) [(2.89±0.11), t=5.78, P<0.001; (1.92±0.13), t=6.85, P<0.001]. For rats with pulmonary fibrosis, all had different degrees of lung enlargement, increased lung specific gravity, decreased Cst, and increased lung inflammation and fibrosis[(0.96±0.06), t=19.76, P<0.001; (0.26±0.09), t=17.64, P<0.001; (3.63±1.51), t=6.00, P<0.001; (1.75±0.71), t=5.84, P<0.001]. After CEP gavage, rats that had RA complicated with pulmonary fibrosis had reduced lung swelling, decreased lung specific gravity, increased Cst [(0.82±0.05), t=5.76, P<0.001; (0.43±0.18), t=2.31, P=0.038], and the scores of pulmonary fibrosis and inflammation [(3.00±1.00); (1.56±0.52)] all showed a trend of decrease, but did not reach statistical difference CEP inhibited the expression of TGF-β 1, TGFβ-R2, α-SMA, Fn and JAK2 in lung tissue of pulmonary fibrosis rats, and the differences among the five groups were statistically significant ( F=9.02, P=0.017; F=4.86, P=0.048; F=6.57, P=0.032; F=11.26, P=0.010; F=13.32, P=0.007). ② In vitro study, TGF-β 1 stimulated HFL1 showed stronger phosphorylated JAK2 (p-JAK2) fluorescent signal WB showed a significant increase in the expression of TGFβ-R2, α-SMA, JAK2 and Col1, and after LY and CEP intervention, the above proteins were reduced in a concentration-dependent manner, with statistically significant differences among all five groups ( F=337.30, P<0.001; F=20.61, P<0.001; F=100.60, P<0.001; F=180.90, P<0.001). Conclusion:JAK2 inhibitors can ameliorate RA-related pulmonary fibrosis, and the mechanism may be through interfering with the "crosstalk" between JAK2 and TGF-β 1 signaling pathway.

P-gp Inhibition by XL019, a JAK2 Inhibitor, Increases Apoptosis of Vincristine-treated Resistant KBV20C Cells with Increased p21 and pH2AX Expression.

The present study was designed to identify conditions that could increase the sensitivity of resistant cancer cells to antimitotic drugs. We investigated whether a Janus kinase 2 (JAK2) inhibitor used in clinical trials, XL019, sensitizes antimitotic drug-resistant KBV20C cells. XL019 reduced cellular viability and increased apoptosis in vincristine-treated KBV20C cells, independently of the JAK/signal transducer and activator of transcription (STAT) pathway. Based on the ATP-binding cassette protein B1 [ABCB1, P-glycoprotein (P-gp)] inhibitory assay, we demonstrated that XL019 functions as a P-gp inhibitor in drug-resistant KBV20C cells. Considering that another JAK2 inhibitor, CEP-33779, also inhibited P-gp and sensitized drug-resistant cancer cells in a previous study, we concluded that JAK2 inhibitors can be used as P-gp inhibitors in drug-resistant cancer cells. Fluorescence-activated cell sorting, western blot, and annexin V analyses were used to further investigate the mechanism of action of XL019 in vincristine-treated KBV20C cells. XL019 induced early apoptosis of KBV20C cells in response to vincristine treatment via increased G2 phase arrest. Moreover, G2 phase arrest and apoptosis of cells co-treated with vincristine and XL019 resulted from the up-regulation of phosphorylated retinoblastoma protein (pRb), p21, and the DNA-damage protein, phosphorylated H2A histone family, member X (pH2AX). Additionally, the P-gp-inhibitory effect of XL019 was less than that of CEP-33779, and a more than 2-fold higher dose was required to sensitize vincristine-treated KBV20C cells. Furthermore, lower doses of XL019 were required to sensitize KBV20C cells to a degree similar to that obtained with the established P-gp inhibitor verapamil, suggesting that XL019 has higher specificity than verapamil. Our results showed that JAK2 inhibitors inhibited P-gp action via a direct binding mechanism, which was similar to that of verapamil. These findings indicate that JAK2 inhibitors may be promising therapeutics for the treatment of cancer that is resistant to antimitotic drugs.

The JAK2 inhibitors CEP-33779 and NVP-BSK805 have high P-gp inhibitory activity and sensitize drug-resistant cancer cells to vincristine.

P-glycoprotein (P-gp) is overexpressed in cancer cells in order to pump out chemotherapeutic drugs, and is one of the major mechanisms responsible for multidrug resistance (MDR). It is important to identify P-gp inhibitors with low toxicity to normal cells in order to increase the efficacy of anti-cancer drugs. Previously, a JAK2 inhibitor CEP-33779 demonstrated inhibitory actions against P-gp and an ability to sensitize drug-resistant cancer cells to treatment. In the present study, we tested another JAK2 inhibitor NVP-BSK805 for P-gp inhibitory activity. In molecular docking simulation modeling, NVP-BSK805 showed higher binding affinity docking scores against a P-gp member (ABCB1) than CEP-33779 did. Furthermore, we found that lower doses of NVP-BSK805 are required to inhibit P-gp in comparison with that of CEP-33779 or verapamil (an established P-gp inhibitor) in KBV20C cells, suggesting that NVP-BSK805 has higher specificity. NVP-BSK805, CEP-33779, and verapamil demonstrated similar abilities to sensitize KBV20C cells to vincristine (VIC) treatment. Our results suggested that the JAK2 inhibitors were able to inhibit P-gp pump-action via a direct binding mechanism, similar to verapamil. However, JAK2 inhibitor-induced sensitization was not observed in VIC-treated sensitive KB parent cells, suggesting that these effects are specific to resistant cancer cells. FACS, western-blot, and annexin V analyses were used to further investigate the mechanism of action of JAK2 inhibitors in VIC-treated KBV20C cells. Both CEP-33779 and NVP-BSK805 induced the sensitization of KBV20C cells to VIC treatment via the same mechanisms; they each caused a reduction in cell viability, increased G2 arrest, and upregulated expression of the DNA damaging protein pH2AX when used as co-treatments with VIC. These findings indicate that inhibition of JAK2 may be a promising target in the treatment of cancers that are resistant to anti-mitotic drugs.

JAK2 inhibitor CEP-33779 prevents mouse oocyte maturation in vitro.

The inhibitor CEP-33779 is a specific selective inhibitor of Janus kinase 2 (JAK2). In most somatic cells, JAK2 plays essential roles in cellular signal transduction and in the regulation of cell cycle. Little is known regarding the effects of JAK2 on mammalian oocyte maturation. In the present study, we investigated the effects of CEP-33779 on mouse oocytes' meiosis and the possible mechanisms of JAK2 during mouse oocyte maturation. We detected the distribution of JAK2 during the mouse oocyte maturation. The results showed that JAK2 was mainly distributed in the cytoplasm during maturation. We cultured mouse oocytes with CEP-33779, examined the maturation rate, spindle morphology, and organization of microfilaments during the mouse oocyte maturation. While the rate of germinal vesicle breakdown (GVBD) did not differ between the treated and control groups, the rate of oocyte maturation decreased significantly when treated with CEP-33779. The rate of maturation was 21.14% in treated group and was 81.44% in control group. The results show that CEP-33779 inhibits the maturation of mouse oocytes. There was no obvious difference in the meiotic spindle morphology between the treated and control groups. The results show that CEP-33779 treatment did not disrupt the reorganization of microtubules. The microfilament observation shows that the microfilament did not form actin cap and the spindle stayed at the center of the oocyte in the treated group. CEP-33779 treatment inhibited the maturation of mouse oocytes which might be because of the disruption of formation of the actin cap. These results suggest that JAK2 regulated the microfilaments aggregation during the mouse oocyte maturation.

CEP-33779 antagonizes ATP-binding cassette subfamily B member 1 mediated multidrug resistance by inhibiting its transport function.

The overexpression of ATP-binding cassette (ABC) transporters often leads to the development of multidrug resistance (MDR), which is the major factor contributing to the failure of chemotherapy. The objective of this study was to investigate the enhancement of CEP-33779, a small-molecule inhibitor of Janus kinase 2 (JAK2), on the efficacy of conventional chemotherapeutic agents in MDR cells with overexpression of P-glycoprotein (ABCB1), multidrug resistance-associated protein 1 (ABCC1) and breast cancer resistance protein (ABCG2). Our results showed that CEP-33779, at nontoxic concentrations, significantly sensitized ABCB1 overexpressing MDR cells to its anticancer substrates. CEP-33779 significantly increased intracellular accumulation and decreased the efflux of doxorubicin by inhibiting the ABCB1 transport function. Furthermore, CEP-33779 did not alter the expression of ABCB1 both at protein and mRNA levels but did stimulate the activity of ABCB1 ATPase. CEP-33779 was predicted to bind within the large hydrophobic cavity of homology modeled ABCB1. In addition, the down-regulation of JAK2 by shRNA altered neither the expression of ABCB1 nor the cytotoxic effect of chemotherapeutic agents in ABCB1-overexpressing cells. Significantly, CEP-33779 enhanced the efficacy of vincristine against the ABCB1-overexpressing and drug resistant KBv200 cell xenograft in nude mice. In conclusion, we conclude that CEP-33779 enhances the efficacy of substrate drugs in ABCB1-overexpressing cells by directly inhibiting ABCB1 transport function. The findings encouraged to further study on the combination therapy of CEP-33779 with conventional chemotherapeutic agents in ABCB1 mediated-MDR cancer patients.