An orthotopic syngeneic mouse model of bortezomib-resistant multiple myeloma.

While bortezomib has significant benefits in multiple myeloma (MM) therapy, the disease remains incurable due to the invariable development of bortezomib resistance. This emphasises the need for advanced models for preclinical evaluation of new therapeutic approaches for bortezomib-resistant MM. Here, we describe the development of an orthotopic syngeneic bortezomib-resistant MM mouse model based on the most well-characterised syngeneic MM mouse model derived from spontaneous MM-forming C57BL/KaLwRij mice. Using bortezomib-resistant 5TGM1 cells, we report and characterise a robust syngeneic mouse model of bortezomib-resistant MM that is well suited to the evaluation of new therapeutic approaches for proteasome inhibitor-resistant MM.

Ceramide-induced integrated stress response overcomes Bcl-2 inhibitor resistance in acute myeloid leukemia.

Inducing cell death by the sphingolipid ceramide is a potential anticancer strategy, but the underlying mechanisms remain poorly defined. In this study, triggering an accumulation of ceramide in acute myeloid leukemia (AML) cells by inhibition of sphingosine kinase induced an apoptotic integrated stress response (ISR) through protein kinase R-mediated activation of the master transcription factor ATF4. This effect led to transcription of the BH3-only protein Noxa and degradation of the prosurvival Mcl-1 protein on which AML cells are highly dependent for survival. Targeting this novel ISR pathway, in combination with the Bcl-2 inhibitor venetoclax, synergistically killed primary AML blasts, including those with venetoclax-resistant mutations, as well as immunophenotypic leukemic stem cells, and reduced leukemic engraftment in patient-derived AML xenografts. Collectively, these findings provide mechanistic insight into the anticancer effects of ceramide and preclinical evidence for new approaches to augment Bcl-2 inhibition in the therapy of AML and other cancers with high Mcl-1 dependency.

An Orally Bioavailable and Highly Efficacious Inhibitor of CDK9/FLT3 for the Treatment of Acute Myeloid Leukemia.

Mutations in FMS-like tyrosine kinase 3 (FLT3) occur in approximately one-third of AML patients and are associated with a particularly poor prognosis. The most common mutation, FLT3-ITD, is a self-activating internal tandem duplication (ITD) in the FLT3 juxtamembrane domain. Many FLT3 inhibitors have shown encouraging results in clinical trials, but the rapid emergence of resistance has severely limited sustainable efficacy. Co-targeting of CDK9 and FLT3 is a promising two-pronged strategy to overcome resistance as the former plays a role in the transcription of cancer cell-survival genes. Most prominently, MCL-1 is known to be associated with AML tumorigenesis and drug resistance and can be down-regulated by CDK9 inhibition. We have developed CDDD11-8 as a potent CDK9 inhibitor co-targeting FLT3-ITD with Ki values of 8 and 13 nM, respectively. The kinome selectivity has been confirmed when the compound was tested in a panel of 369 human kinases. CDDD11-8 displayed antiproliferative activity against leukemia cell lines, and particularly potent effects were observed against MV4-11 and MOLM-13 cells, which are known to harbor the FLT3-ITD mutation and mixed lineage leukemia (MLL) fusion proteins. The mode of action was consistent with inhibition of CDK9 and FLT3-ITD. Most importantly, CDDD11-8 caused a robust tumor growth inhibition by oral administration in animal xenografts. At 125 mg/kg, CDDD11-8 induced tumor regression, and this was translated to an improved survival of animals. The study demonstrates the potential of CDDD11-8 towards the future development of a novel AML treatment.

Resensitising proteasome inhibitor-resistant myeloma with sphingosine kinase 2 inhibition.

The introduction of the proteasome inhibitor bortezomib into treatment regimens for myeloma has led to substantial improvement in patient survival. However, whilst bortezomib elicits initial responses in many myeloma patients, this haematological malignancy remains incurable due to the development of acquired bortezomib resistance. With other patients presenting with disease that is intrinsically bortezomib resistant, it is clear that new therapeutic approaches are desperately required to target bortezomib-resistant myeloma. We have previously shown that targeting sphingolipid metabolism with the sphingosine kinase 2 (SK2) inhibitor K145 in combination with bortezomib induces synergistic death of bortezomib-naïve myeloma. In the current study, we have demonstrated that targeting sphingolipid metabolism with K145 synergises with bortezomib and effectively resensitises bortezomib-resistant myeloma to this proteasome inhibitor. Notably, these effects were dependent on enhanced activation of the unfolded protein response, and were observed in numerous separate myeloma models that appear to have different mechanisms of bortezomib resistance, including a new bortezomib-resistant myeloma model we describe which possesses a clinically relevant proteasome mutation. Furthermore, K145 also displayed synergy with the next-generation proteasome inhibitor carfilzomib in bortezomib-resistant and carfilzomib-resistant myeloma cells. Together, these findings indicate that targeting sphingolipid metabolism via SK2 inhibition may be effective in combination with a broad spectrum of proteasome inhibitors in the proteasome inhibitor resistant setting, and is an approach worth clinical exploration.

Discovery of a potent, highly selective, and orally bioavailable inhibitor of CDK8 through a structure-based optimisation.

CDK8 is deregulated in multiple types of human cancer and is viewed as a therapeutic target for the treatment of the disease. Accordingly, the search for small-molecule inhibitors of CDK8 is being intensified. Capitalising on our initial discovery of AU1-100, a potent CDK8 inhibitor yet with a limited degree of kinase selectivity, a structure-based optimisation was carried out, with a series of new multi-substituted pyridines rationally designed, chemically prepared and biologically evaluated. Such endeavour has culminated in the identification of 42, a more potent CDK8 inhibitor with superior kinomic selectivity and oral bioavailability. The mechanism underlying the anti-proliferative effect of 42 on MV4-11 cells was studied, revealing that the compound arrested the G1 cell cycle and triggered apoptosis. The low risk of hepato- and cardio-toxicity of 42 was estimated. These findings merit further investigation of 42 as a targeted cancer therapeutic.

Potent and orally bioavailable CDK8 inhibitors: Design, synthesis, structure-activity relationship analysis and biological evaluation.

CDK8 regulates transcription either by phosphorylation of transcription factors or, as part of a four-subunit kinase module, through a reversible association of the kinase module with the Mediator complex, a highly conserved transcriptional coactivator. Deregulation of CDK8 has been found in various types of human cancer, while the role of CDK8 in supressing anti-cancer response of natural killer cells is being understood. Currently, CDK8-targeting cancer drugs are highly sought-after. Herein we detail the discovery of a series of novel pyridine-derived CDK8 inhibitors. Medicinal chemistry optimisation gave rise to 38 (AU1-100), a potent CDK8 inhibitor with oral bioavailability. The compound inhibited the proliferation of MV4-11 acute myeloid leukaemia cells with the kinase activity of cellular CDK8 dampened. No systemic toxicology was observed in the mice treated with 38. These results warrant further pre-clinical studies of 38 as an anti-cancer agent.

Vincristine upregulates PD-L1 and increases the efficacy of PD-L1 blockade therapy in diffuse large B-cell lymphoma.

BACKGROUND: Some chemotherapy drugs have immunomodulatory effects on specific tumors. The potential of vincristine (VCR) in the R-CHOP regimen to act as both a chemotherapeutic and an immunomodulatory agent via PD-L1 in tumor cells remains unclear. METHODS: In vitro screening VCR showed that the IC50 value of VCR in the DLBCL cell lines was approximately 2 nM. Western blotting and q-PCR were used to detect the expression of PD-L1. The effect of VCR combined with PD-L1 mAb was tested in a co-culture system of LY-OCI-3 cells and peripheral blood mononuclear cells and in DLBCL xenograft mouse model. Flow cytometry was used to determine the proportion of T lymphocyte subsets. The effect of the STAT3 inhibitor nifuroxazide on VCR-induced PD-L1 expression was tested in LY-OCI-3 and SU-DHL-4 cells. RESULTS: VCR upregulated PD-L1 protein and mRNA expression in various DLBCL cell lines. PD-L1 Ab combined with VCR significantly increased the proportion of CD8 + Granzyme B + , INF-γ + or TNF-α + CD3 + T cells. VCR + PD-L1 Ab inhibited tumor growth more effectively than VCR monotherapy, whereas PD-L1 Ab alone had no significant effect. Survival time did not differ significantly between the PD-L1 Ab group and the control group, whereas it was significantly longer in the VCR monotherapy and combination groups which showed more longer survival compared with the former. Nifuroxazide downregulated p-STAT3 and PD-L1 protein levels. CONCLUSIONS: VCR upregulated PD-L1 expression in DLBCL cells partially by promoting the p-STAT3; VCR combined with PD-L1 Ab activated effector T cells and increased the antitumor immune response in vitro and in vivo.

Prostaglandin E2 accelerated recovery of chemotherapy-induced intestinal damage by increasing expression of cyclin D.

Intestinal stem cells (ISCs) play a crucial role in maintaining intestinal homeostasis upon chemotherapy and radiotherapy. It has been documented that prostaglandin E2 (PGE2) treatment improved hematopoietic stem cell function in vitro and in vivo, while the relationship between PGE2 and intestinal stem cells remains unclear. Presently, mice were exposed to PGE1, dmPGE2 and indomethacin. Numbers and function of ISCs were assessed by analyzing Olfm4+ ISCs. Intestinal protection of dmPGE2 was investigated on a 5-fluorouracil (5FU)-induced intestinal damage mouse model. The results showed that dmPGE2 treatment, but not PGE1, increased numbers of Olfm4+ ISCs in dose- and time-dependent manners. Indomethacin treatment decreased numbers of Olfm4+ ISCs. The beneficial effects of short-term dmPGE2 treatment on intestine were supported in a 5FU-induced intestinal damage model. Our data showed that 5FU treatment significantly decreased numbers of Olfm4+ ISCs and goblet cells in intestine, which could be ameliorated by dmPGE2 treatment. dmPGE2 treatment accelerated the recovery of 5FU-induced ISC injury via increasing expression of cyclin D1 and D2 in intestine. Furthermore, dmPGE2 treatment-induced expression of cyclin D1 and D2 might be mediated by up-regulation of FOXM1 expression in intestine. These findings feature PGE2 as an effective protector against chemotherapy-induced intestinal damage.

Polyinosinic-polycytidylic acid accelerates intestinal stem cell proliferation via modulating Myc expression.

It is well known that exposure of double-stranded RNA (dsRNA) to intestine immediately induces villus damage with severe diarrhea, which is mediated by toll-like receptor 3 signaling activation. However, the role of intestinal stem cells (ISCs) remains obscure during the pathology. In the present study, polyinosinic-polycytidylic acid (poly[I:C]), mimicking viral dsRNA, was used to establish intestinal damage model. Mice were acutely and chronically exposed to poly(I:C), and ISCs in jejunum were analyzed. The results showed that the height of villus was shorter 48 hr after acute poly(I:C) exposure compared with that of controls, while chronic poly(I:C) treatment increased both villus height and crypt depth in jejunum compared with control animals. The numbers of ISCs in jejunum were significantly increased after acute and chronic poly(I:C) exposure. Poly (I:C)-stimulated ISCs have stronger capacities to differentiate into intestine endocrine cells. Mechanistically, poly(I:C) treatment increased expression of Stat1 and Axin2 in the intestinal crypt, which was along with increased expression of Myc, Bcl2, and ISC proliferation. These findings suggest that dsRNA exposure could induce ISC proliferation to ameliorate dsRNA-induced intestinal injury.

Isoprenaline protects intestinal stem cells from chemotherapy-induced damage.

BACKGROUND AND PURPOSE: Damage to intestinal epithelial cells and mucosa limits the effectiveness of several anti-cancer chemotherapeutic agents but the underlying mechanism (s) remain unknown. Little is known of how enteric nervous system regulates proliferation, differentiation, impairment, and regeneration of intestinal stem cells. Here we have investigated the effects of isoprenaline on the damaged intestinal stem cells induced by chemotherapeutic treatments in mice. EXPERIMENTAL APPROACH: The effects of inhibiting sympathetic and parasympathetic nerves on intestinal stem cells were examined in male C57BL/6J mice. Protection by isoprenaline of intestinal stem cells was assessed in the presence or absence of 5-fluorouracil (5FU) or cisplatin. Cellular apoptosis, cell cycle, PI3K/Akt signalling, and NF-κB signalling in intestinal stem cells were mechanistically evaluated. KEY RESULTS: The sympathetic nerve inhibitor 6-OHDA decreased the number and function of intestinal stem cells. 5FU or cisplatin treatment damaged both intestinal stem cells and sympathetic nerves. Notably, isoprenaline accelerated the recovery of intestinal stem cells after 5FU or cisplatin treatment. This protective effect of isoprenaline on damaged intestinal stem cells was mediated by ß2 -adrenoceptors. The benefits of isoprenaline were mainly mediated by inhibiting cellular apoptosis induced by 5FU treatment, which might contribute to fine-tuning regulating NF-κB signalling pathway by isoprenaline administration. CONCLUSIONS AND IMPLICATIONS: Treatment with isoprenaline is a new approach to ameliorate the damage to intestinal stem cells following exposure to cancer chemotherapeutic agents.

Quadratus lumborum block versus transversus abdominis plane block for postoperative pain management after laparoscopic colorectal surgery: A randomized controlled trial.

BACKGROUND: This study aimed to compare the quadratus lumborum block (QLB) method with transversus abdominis plane block (TAPB) for postoperative pain management in patients undergoing laparoscopic colorectal surgery. METHODS: Seventy-four patients scheduled for laparoscopic colorectal surgery were randomly assigned into 2 groups. After surgery, patients received bilateral ultrasound-guided single-dose of QLB or TAPB. Each side was administered with 20 ml of 0.375% ropivacaine. All patients received sufentanil as patient-controlled intravenous analgesia (PCIA). Resting and moving numeric rating scale (NRS) were assessed at 2, 4, 6, 24, 48 hours postoperatively. The primary outcome measure was sufentanil consumption at predetermined time intervals after surgery. RESULTS: Patients in the QLB group used significantly less sufentanil than TAPB group at 24 and 48 hours (P < .05), but not at 6 hours (P = .33) after laparoscopic colorectal surgery. No significant differences in NRS results were found between the two groups at rest or during movement (P > .05). Incidence of dizziness in the QLB group was lower than in TAPB group (P < .05). CONCLUSIONS: The QLB is a more effective postoperative analgesia as it reduces sufentanil consumption compared to TAPB in patients undergoing laparoscopic colorectal surgery.

Synthesis and evaluation of 2'H-spiro[cyclohexane-1,3'-imidazo[1,5-a]pyridine]-1',5'-dione derivatives as Mnk inhibitors.

Post-translational modulation of eIF4E through phosphorylation by Mnks is highly integral to the pathogenesis of different cancers. Therefore, inhibition of Mnks offers a strategy for cancer treatment. Herein, a series of 2'H-spiro[cyclohexane-1,3'-imidazo[1,5-a]pyridine]-1',5'-dione derivatives is presented as Mnk inhibitors. Some of them showed sub-micromolar to low nanomolar inhibitory activities against Mnk1/2 with a high level of selectivity for both kinases over CDKs. Biochemical assays revealed that compounds 4c and 4t are non-ATP-competitive inhibitors of Mnks. Lead compound 4t demonstrated a high selectivity for Mnk1/2 over a selection of 51 kinases, and displayed anti-proliferative activities against a panel of cancer cell lines. However, this compound in combination with our in-house CDK4/6 inhibitor 83 did not show a synergistic effect in A2780 ovarian cancer cells, suggesting that caution be exercised in the selection of an agent to be combined with an Mnk inhibitor.

Discovery of CDK5 Inhibitors through Structure-Guided Approach.

Specific abrogation of cyclin-dependent kinase 5 (CDK5) activity has been validated as a viable approach for the development of anticancer agents. However, no selective CDK5 inhibitor has been reported to date. Herein, a structure-based in silico screening was employed to identify novel scaffolds from a library of compounds to identify potential CDK5 inhibitors that would be relevant for drug discovery. Hits, representatives of three chemical classes, were identified as inhibitors of CDK5. Structural modification of hit-1 resulted in 29 and 30. Compound 29 is a dual inhibitor of CDK5 and CDK2, whereas 30 preferentially inhibits CDK5. Both leads exhibited anticancer activity against acute myeloid leukemia (AML) cells via a mechanism consistent with targeting cellular CDK5. This study provides an effective strategy for discovery of CDK5 inhibitors as potential antileukemic agents.

Ceritinib Enhances the Efficacy of Substrate Chemotherapeutic Agent in Human ABCB1-Overexpressing Leukemia Cells In Vitro, In Vivo and Ex-Vivo.

BACKGROUND/AIMS: Multidrug resistance (MDR) triggered by ATP binding cassette (ABC) transporters, such as ABCB1, ABCC1, and ABCG2, is a key obstacle for successful cancer chemotherapy. There is currently no FDA-approved MDR modulator that can be used in clinic. Ceritinib, a selective ALK inhibitor, has been approved as the second-line treatment for ALK-positive non-small cell lung cancer. Here, we examined the role of ceritinib in leukemia associated MDR in therapy. METHODS: The cell proliferation was detected by MTT assay. The flow cytometry was used to detect the expression of cell surface protein and to detect the accumulation and efflux of rhodamine 123 (Rh123) or doxorubicin (Dox) in cells. The RT-PCR and Western blot were performed to detect the gene expression and protein expression levels, respectively. RESULTS: We found that ceritinib enhanced the efficacy of substrate chemotherapeutic agent in ABCB1-overexpressing K562/adr leukemia cells both in vitro and in vivo models, but neither in sensitive parental K562 leukemia cells nor in ABCC1-overexpressing HL-60/adr leukemia cells. Mechanistically, ceritinib significantly increased the intracellular accumulation of Rh123 or Dox but did neither alter ABCB1 expressions at both protein and mRNA levels nor block the phosphorylations of AKT and ERK1/2 at the concentration of MDR reversal. Importantly, ceritinib also increased the intracellular accumulation of Dox and enhanced the efficacy of Dox in primary leukemia cells in ex-vivo. CONCLUSION: Our results suggested that ceritinib enhanced the efficacy of substrate chemotherapeutic agent on inhibition of leukemia cell growth in vitro, in vivo and ex-vivo, which linked to block ABCB1 function, pumping out its substrate conventional chemotherapeutic agent, thereby increasing the intracellular accumulation. These suggest the combination of ceritinib and substrate chemotherapeutic drugs maybe an effective treatment of resistant leukemia patients with ABCB1-mediated MDR.

Chronic Schistosoma japonicum infection reduces immune response to vaccine against hepatitis B in mice.

BACKGROUND: Hepatitis B and schistosomiasis are most prevalent in Africa and Asia, and co-infections of both are frequent in these areas. The immunomodulation reported to be induced by schistosome infections might restrict immune control of hepatitis B virus (HBV) leading to more severe viral infection. Vaccination is the most effective measure to control and prevent HBV infection, but there is evidence for a reduced immune response to the vaccine in patients with chronic schistosomiasis japonica. METHODOLOGY/PRINCIPAL FINDINGS: In this paper, we demonstrate in a mouse model that a chronic Schistosoma japonicum infection can inhibit the immune response to hepatitis B vaccine (HBV vaccine) and lead to lower production of anti-HBs antibodies, interferon-γ (IFN-γ) and interleukin-2 (IL-2). After deworming with Praziquantel (PZQ), the level of anti-HBs antibodies gradually increased and the Th2-biased profile slowly tapered. At 16 weeks after deworming, the levels of anti-HBs antibodies and Th1/Th2 cytokines returned to the normal levels. CONCLUSIONS/SIGNIFICANCE: The results suggest that the preexisting Th2-dominated immune profile in the host infected with the parasite may down-regulate levels of anti-HBs antibodies and Th1 cytokines. To improve the efficacy of HBV vaccination in schistosome infected humans it may be valuable to treat them with praziquantel (PZQ) some time prior to HBV vaccination.

[Ageing down-modulates the immune responses to Schistosoma japonicum infection in mice].

OBJECTIVE: To investigate the effect of ageing on the immune responses against Schistosoma japonicum infection in mice. METHODS: Female BALB/c mice were divided into young group (2 months) and old group (18 months), each composed of 8 mice. Each mouse was percutaneously infected with 40 +/- 1 S. japonicum cercariae. At 6 weeks post-infection, the mice were sacrificed, and the spleens were removed and single-cell suspensions of splenocytes were prepared. Worms were perfused from hepatic portal system and counted. The number of eggs in the liver was determined after KOH digestion. Mean single-egg granulomas sizes were determined in stained histological sections. Splenocyte proliferation responses were analyzed by MTT colorimetry. Level of interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) in the splenocyte culture supernatants was determined by ELISA. RESULTS: The worm burden and egg per gram of liver in old mice [19.75 +/- 1.95, (1.59 +/- 1.05) x 10(4)] were significantly lower than that of young mice [26.00 +/- 2.42, (208 +/- 0.87) x 10(4)] (P < 0.05). The mean volume of single-egg granulomas of the livers in old mice [(30.13 +/- 10.97) x 10(3) mm3] was significantly lower than that of the young mice [(47.02 +/- 24.13) x l0(3) mm3] (P < 0.05). RESULTS: of T cell proliferation showed that the splenocytes had poorer immune reactivity to ConA in old mice (SI: 1.08 +/- 0.12) than that in young mice (SI: 131 +/- 0.14) (P < 0.05). Levels of IFN-gamma and IL-4 in the splenocyte culture supernatants [(24.05 +/- 6.24), (4.15 +/- 0.68) pg/ml] from old mice were lower than that of young mice [(34.25 +/- 869), (7125 +/- 0.83) pg/ml](P < 0.05). CONCLUSION: Ageing down-modulates the immune responses and the poorer immune reactivity might decrease pathological alterations in mice infected with Schistosoma japonicum.

Cimetidine enhances the protective effect of GST DNA vaccine against Schistosoma japonicum.

Cimetidine (CIM), a histamine-2-receptor antagonist, has a long history of safe use in gastric acid-mediated gastrointestinal disorders. In this study, we used CIM, as an adjuvant, with pEGFP-Sj26 GST (the recombinant plasmid containing enhanced green fluorescent protein gene and the gene encoding 26 kDa glutathione S-transferase of Schistosoma japonicum) DNA vaccine to immunized mice and attempted to enhance the protective effect against S. japonicum. The results showed that the reduction rate of worm and egg burdens in the pEGFP-Sj26GST plus CIM group were 79.0% and 68.4%, respectively, significantly higher than that in pEGFP-Sj26GST alone group (27.0% and 22.5%, P<0.01). Compared with the pEGFP-Sj26GST alone group, mice immunized with pEGFP-Sj26GST plus CIM showed an elevated level of IFN-γ and IL-12 and a low level of IL-10 in splenocytes, while the levels of IL-4 and IL-5 showed no difference between the two groups. Our data also demonstrated that the percentage of CD4(+)CD25(+) regulatory T cells (Tregs) was significantly decreased in the spleens of mice immunized with pEGFP-Sj26GST plus CIM. All these findings suggest that CIM as a potential schistosome DNA vaccine adjuvant can enhance the protective effect of pEGFP-Sj26GST vaccine.

Detection of circulating antigen in serum of mice infected with Schistosoma japonicum by immunomagnetic bead ELISA based on IgY.

We developed a novel immunomagnetic bead ELISA based on IgY (egg yolk immunoglobulin) for detection of circulating antigen (CA) in sera of mice infected with Schistosoma japonicum. The assay involved the use of chicken polyclonal antibodies IgY against soluble egg antigens (SEA) of S. japonicum as a capture antibody and anti-SEA mouse monoclonal antibody NP28-5B labeled horseradish peroxidase (HRP) as a detecting antibody. Two groups of BALB/c mice infected with S. japonicum cercariae were used: lightly infected mice (infected with 10 S. japonicum cercariae) and heavily infected mice (infected with 30 S. japonicum cercariae). The CA was detectable as early as 4 and 5 weeks after infection in the sera of heavily and lightly infected mice, respectively. The CA levels rose rapidly and reached a peak in 8 weeks after infection and then remained a plateau for at least another 6 weeks in both groups. Moreover, the effect of praziquantel on the CA levels was also investigated. The heavily infected mice were treated with praziquantel and the CA levels in sera increased dramatically in the first week post-treatment and then decreased to the control level by 6 weeks after treatment. The novel assay appears to be sensitive for detection of schistosomal antigenemia and valuable to judge the efficacy of chemotherapy in murine schistosomiasis.

[Effect of MNNG on ornithine decarboxylase activity in cells from adult Schistosoma japonicum].

OBJECTIVE: To observe the change of ornithine decarboxylase(ODC) activity in cells from adult Schistosoma japonicum after the cells were treated with N-Methyl-N-Nitro-N-Nitrosoguanidine (MNNG). METHODS: The cells were treated with MNNG at a concentration of 3 micrograms/ml for 48 hours after the cells being incubated for one week. The cells were then cultured with RPMI-1640 containing 10% calf serum. ODC activity was detected with spectrophotography. RESULTS: ODC activity rose significantly in two to three weeks after the cells were treated with MNNG. CONCLUSION: There was ODC activity in cells from adult S. japonicum and MNNG has an effect to reinforce ODC activity in the cells.