Novel Midkine Inhibitor Induces Cell Cycle Arrest and Apoptosis in Multiple Myeloma

BACKGROUND/AIM

Multiple myeloma (MM), the second most common hematological malignancy, is characterized by the accumulation of malignant plasma cells within the bone marrow. Despite various drug classes for MM treatment, it remains incurable, necessitating novel and efficacious agents. This study aims to explore the anti-cancer activity of a midkine inhibitor, iMDK (C21H13FN2O2S), in myeloma cell lines.

MATERIALS AND METHODS

This study assessed the antiproliferative activity using the MTT assay. Cell cycle and apoptosis were evaluated using flow cytometry. To further investigate the inhibitory mechanism, western blotting was used to detect cell cycle-related proteins, pro-apoptotic proteins, and anti-apoptotic proteins.

RESULTS

iMDK inhibits MM cell proliferation in a dose- and time-dependent manner, inducing cell cycle arrest and apoptosis. The reduction in Cdc20 expression by iMDK treatment leads to G2/M phase cell cycle arrest. Furthermore, iMDK down-regulates anti-apoptotic proteins (Bcl-2, Bcl-xL, Mcl-1, and c-FLIP), thereby activating both intrinsic and extrinsic apoptosis pathways.

CONCLUSION

iMDK could be a potential candidate for MM treatment.

Antitumor effect of acanthoic acid against primary effusion lymphoma via inhibition of c-FLIP

Acanthoic acid (AA) is an active substance that is extracted from Croton oblongifolius Roxb., a traditional plant in Thailand. The antiinflammatory effect of AA on NF-κB pathway has been exclusively reported, however, its anticancer effect is still lacking. PEL is a B cell lymphoma that is mostly found in HIV patients. The prognosis and progression of PEL patients are terribly poor with a median survival time less than 6 months, so the new effective treatment is urgently needed. In this study, we found that AA effectively inhibited PEL cell proliferation with IC50s at 120-130 μM in well-representative cells, while the IC50s of AA in PBMC were higher (>200 μM). AA increased percentages of Annexin V/PI positive cells, whereas adding of caspase inhibitor (Q-VD-OPh) prevented AA-induced cell death. The antiapoptotic protein, c-FLIP, was downregulated by AA which leading to the activation of caspase-8 and -3. Combination of AA and TRAIL dramatically enhanced apoptotic cell death. In PEL xenograft model, AA at the dose of 250 mg/kg effectively inhibited PEL tumor growth without detectable toxicities assessed by mice weight and appearance.

Cucurbitacin B induces apoptosis of primary effusion lymphoma via disruption of cytoskeletal organization

BACKGROUND

Primary effusion lymphoma (PEL) is an aggressive B cell non-Hodgkin lymphoma that develops especially in AIDS patients and immunocompromised patients infected with human herpes virus-8 (HHV-8)/Kaposi's sarcoma-associated herpesvirus (KSHV). PEL has a poor prognosis in patients despite conventional chemotherapeutic treatment, and a safe and efficient therapy is required.

PURPOSE

To examine the effects on PEL of cucurbitacin B (CuB), a triterpene found in plants of the Cucurbitaceae family that has several anti-cancer activities.

STUDY DESIGN

We evaluated the anti-cancer activities of CuB in vitro and in vivo.

METHODS

Cell proliferation of PEL cell lines was measured by MTT assay. Cleaved caspases and signaling transduction associated proteins were analyzed by western blotting. Wright and Giemsa staining and immunofluorescence staining were carried out to observe cell morphology. Cell cycles were analyzed by flow cytometry. RT-PCR was performed to detect viral gene expressions. A xenograft mouse model was employed to evaluate the anti-cancer activity of CuB in vivo.

RESULTS

CuB inhibited cell proliferation of PEL cell lines (BCBL-1, BC-1, GTO and TY-1) in a dose-dependent manner (0-50 nM) and induced apoptosis of BCBL-1 cells via caspase activation in a dose- and time-dependent manner. In addition, CuB caused cell-shape disruption by inducing actin aggregation and suppressing the p-cofilin level, resulting in BCBL-1 cell arrest at the G2/M phase. In contrast, CuB showed almost no suppression of p-STAT3 and p-Akt activation, which were constitutively activated by KSHV-derived proteins. Furthermore, CuB (0.5 mg/kg) via intraperitoneal injection significantly (p < 0.05) suppressed solid tumor growth in the xenograft mouse model.

CONCLUSION

This study suggests that CuB is a promising agent for PEL treatment.

A novel synthetic acanthoic acid analogues and their cytotoxic activity in cholangiocarcinoma cells

A novel series of acanthoic acid analogues containing triazole moiety were synthesized through esterification and CuAAC reaction. Evaluation of their biological activities against four cell lines of cholangiocarcinoma cells showed that 3d exhibited the strongest activity with an IC₅₀ value of 18 µM against KKU-213 cell line, which was 8 fold more potent than acanthoic acid. Interestingly, the triazole ring and nitro group on benzyl ring play very significant role in cytotoxic activity. The computational studies revealed that 3d occupies the binding energy of -12.7 and -10.8 kcal/mol with CDK-2 and EGFR protein kinases, respectively. This result might provide a beginning for the development of acanthoic acid analogues as an anticancer agent.

Anti-human CD99 antibody exerts potent antitumor effects in mantle cell lymphoma

CD99 is a surface molecule expressed on various cell types including cancer cells. Expression of CD99 on multiple myeloma is associated with CCND1-IGH fusion/t(11;14). This translocation has been reported to be a genetic hallmark of mantle cell lymphoma (MCL). MCL is characterized by overexpression of cyclin D1 and high tumor proliferation. In this study, high expression of CD99 on MCL cell lines was confirmed. Our generated anti-CD99 monoclonal antibody (mAb), termed MT99/3, exerted potent antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) activities against mantle B-cell lymphoma without direct cytotoxic effects. The anti-tumor activities of mAb MT99/3 were more effective in MCL than in other B-cell lymphomas. Moreover, in a mouse xenograft model using Z138 MCL cell line, treatment of mAb MT99/3 reduced tumor development and growth. Our study indicated that mAb MT99/3 is a promising immunotherapeutic candidate for mantle cell lymphoma therapy.

Chromomycin A3 suppresses cholangiocarcinoma growth by induction of S phase cell cycle arrest and suppression of Sp1‑related anti‑apoptotic proteins

Cholangiocarcinoma (CCA) is a cancer of biliary epithelium. Late diagnosis and resistance to conventional chemotherapy are the major obstacles in CCA treatment. Increased expression of anti‑apoptotic proteins are observed in CCA, which might confer chemoresistance. Thus, modulations of anti‑apoptotic proteins leading to apoptotic induction is the focus of this study. Chromomycin A3 (CMA3), an anthraquinone glycoside‑mithramycin A analog, was selected. CMA3 strongly binds to GC‑rich regions in DNA, where specificity protein 1 (Sp1), a common transcription factor of apoptosis‑related proteins, is preferentially bounded. The effects of CMA3 on anti‑proliferation, cell cycle arrest and apoptosis induction in CCA cells were demonstrated by MTT assay, flow cytometry and western blot analysis. The results showed CMA3 suppressed cell proliferation in vitro in the nM range. At low doses, CMA3 inhibited cell cycle progression at S phase, while it promoted caspase‑dependent apoptosis at higher doses. CMA3 induced effects of apoptosis were through the suppression of Sp1‑related anti‑apoptotic proteins, FADD‑like IL‑1β‑converting enzyme‑inhibitory protein, myeloid cell leukemia‑1, X‑linked inhibitor of apoptosis protein, cellular inhibitor of apoptosis and survivin. The anti‑CCA effects of CMA3 were confirmed in the xenograft mouse model. CMA3 retarded xenograft tumor growth. Taken together, CMA3 induced apoptosis in CCA cells by diminishing the Sp1‑related anti‑apoptotic proteins is demonstrated. CMA3 might be useful as a chemosensitizing agent.

Dependency of Cholangiocarcinoma on Cyclin D-Dependent Kinase Activity

Cholangiocarcinoma (CCA) is a bile duct cancer with a very poor prognosis. Currently, there is no effective pharmacological treatment available for it. We showed that CCA ubiquitously relies on cyclin-dependent kinases 4 and 6 (CDK4/6) activity to proliferate. Primary CCA tissues express high levels of cyclin D1 and the specific marker of CDK4/6 activity, phospho-RB Ser780. Treatment of a 15-CCA cell line collection by pharmacological CDK4/6 inhibitors leads to reduced numbers of cells in the S-phase and senescence in most of the CCA cell lines. We found that expression of retinoblastoma protein (pRB) is required for activity of the CDK4/6 inhibitor, and that loss of pRB conferred CDK4/6 inhibitor-drug resistance. We also identified that sensitivity of CCA to CDK4/6 inhibition is associated with the activated KRAS signature. Effectiveness of CDK4/6 inhibition for CCA was confirmed in the three-dimensional spheroid-, xenograft-, and patient-derived xenograft models. Last, we identified a list of genes whose expressions can be used to predict response to the CDK4/6 inhibitor. Conclusion: We investigated a ubiquitous dependency of CCA on CDK4/6 activity and the universal response to CDK4/6 inhibition. We propose that the CDK4/6-pRB pathway is a suitable therapeutic target for CCA treatment.

Cyclin d1 depletion interferes with cancer oxidative balance and sensitizes cancer cells to senescence

Expression of cyclin D1 is required for cancer cell survival and proliferation. This is presumably due to the role of cyclin D1 in RB inactivation. Here we investigated the prosurvival function of cyclin D1 in a number of cancer cell lines. We found that cyclin D1 depletion facilitated cellular senescence in several cancer cell lines tested. Senescence triggered by cyclin D1 depletion was more extensive than that caused by the prolonged CDK4 inhibition. Intriguingly, the senescence caused by cyclin D1 depletion was independent of RB status of the cancer cell. We identified a buildup of intracellular reactive oxygen species, in the cancer cells that underwent senescence upon cyclin D1 depletion, but not in CDK4 inhibition, and that ROS buildup was responsible for the senescence. Lastly, the senescence was found to be instigated by the p38/JNK-FOXO3a-p27 pathway. Therefore, expression of cyclin D1 prevents cancer cells from undergoing senescence, at least partially, by keeping the level of intracellular oxidative stress at a tolerable sub-lethal level. Depletion of cyclin D1 promotes the RB-independent pro-senescence pathway, and cancer cell succumbing to the endogenous oxidative stress.

Association of serum high-sensitivity C-reactive protein with metabolic control and diabetic chronic vascular complications in patients with type 2 diabetes

AIMS

To determine an association between hs-CRP and metabolic control/diabetic chronic vascular complications (DCVCCxs) in the patients with type 2 diabetes (DM). In addition, the possibility of using hs-CRP levels to predict risk of DCVCCxs will also be validated.

METHODS

This cohort study randomly enrolled 608 patients with DM during the 2007-2008 study period. We also recorded basic laboratory findings at baseline and at one year, to include fasting plasma glucose, HbA1c, triglyceride, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and hs-CRP.

RESULTS

Logistic regressions of odds ratios between hs-CRP and DCVCCxs (coronary arterial disease, cerebrovascular disease, diabetic nephropathy, diabetic retinopathy, and diabetic peripheral neuropathy) showed significant correlations, except for cerebrovascular disease, as follows 0.2 (0.11-0.38), 0.09 (0.01-0.77), 0.06 (0.02-0.16), 0.31 (0.12-0.82), and 0.17 (0.07-0.43), respectively. Linear regression for changes in hs-CRP were significantly correlated with HbA1c (r=0.38), fasting plasma glucose (r=0.40), triglyceride (r=0.20), low-density lipoprotein cholesterol (r=0.12), and high-density lipoprotein cholesterol (r=-0.12). No correlation was found for total cholesterol (r=0.06). Based on receiver operating characteristic (ROC) analysis, the cut-off points for hs-CRP levels for prediction of DCVCCxs were 2.89, 2.25, 2.10, 2.25, and 2.82mg/L, for coronary arterial disease, cerebrovascular disease, diabetic nephropathy, diabetic retinopathy, and diabetic peripheral neuropathy, respectively.

CONCLUSIONS

Our data showed that DCVCCxs were associated with hs-CRP in patients with DM. The cut-off point for hs-CRP can be used to predict association with DCVCCxs. Well-controlled metabolic components in diabetic patients, especially HbA1c, fasting plasma glucose, and triglyceride may reduce the level of hs-CRP.