Anticancer Activity of Aaptos suberitoides on Glioblastoma Multiforme Cell Line.

OBJECTIVE: Glioblastoma Multiforme (GBM) poses a significant challenge due to its high aggressiveness and unfavorable prognosis, with existing treatments demonstrating limited efficacy in prolonging survival rates. This study aimed to assess the anticancer properties of Aaptos suberitoides extracts and fraction on the U87 cell line, serving as a representative model for GBM. METHODS: U87 cells were treated with ethanol extracts derived from Aaptos suberitoides, specifically two extracts (OAA-1 and OAA-2) and one ethyl acetate fraction (EA) isolated from specimens collected on Pramuka Island and Tinjil Island. The evaluation encompased microscopic observation and MTT assay to determine the IC50. Subsequently, antiproliferative effects were investigated through apoptosis and cell cycle assays. RESULTS: The extract demonstrated cytotoxic activity against U87 cells, with OAA-1 and OAA-2 exhibiting IC50 values of 35.78 µg/mL and 25.38 µg/mL, respectively. OAA-1 notably induced apoptosis at 50 µg/mL and induced cell cycle arrest. On other hand, OAA-2, while also inducing apoptosis significantly, had a lesser impact on cell cycle arrest. In contrast, EA induced significant apoptosis at a concentration of 100 µg/mL. CONCLUSION: The ethanol extracts and the ethyl acetate fraction of Aaptos suberitoides emerged as a promising candidate for Glioblastoma Multiforme cancer therapy, showing potential in inhibiting cell proliferation and inducing apoptosis.

Pyrazoline B-Paclitaxel or Doxorubicin Combination Drugs Show Synergistic Activity Against Cancer Cells: In silico Study.

Background: Multidrug resistance in various cancer types is a major obstacle in cancer treatment. The concept of a single drug molecular target often causes treatment failure due to the complexity of the cellular processes. Therefore, combination chemotherapy, in which two or more anticancer drugs are co-administered, can overcome this problem because it potentially have synergistic efficacy besides reducing resistance, and drug doses. Previously, we reported that pyrazoline B had promising anticancer activity in both in silico and in vitro studies. To increase the efficacy of this drug, co-administration with established anticancer drugs such as doxorubicin and paclitaxel is necessary. Materials and Methods: In this study, we used an in silico approach to predict the synergistic effect of pyrazoline B with paclitaxel or doxorubicin using various computational frameworks and compared the results with those of an established study on the combination of doxorubicin-cyclophosphamide and paclitaxel-ascorbic acid. Results and Discussion: Drug interaction analysis showed the combination was safe with no contraindications or side effects. Furthermore, molecular docking studies revealed that doxorubicin-pyrazoline B and doxorubicin-cyclophosphamide may synergistically inhibit cancer cell proliferation by inhibiting the binding of topoisomerase I to the DNA chain. Moreover, the combination of pyrazoline B-paclitaxel may has synergistic activity to cause apoptosis by inhibiting Bcl2 binding to the Bax fragment or inhibiting cell division by inhibiting α-ß tubulin disintegration. Paclitaxel-ascorbic acid had a synergistic effect on the inhibition of α-ß tubulin disintegration. Conclusion: The results show that this combination is promising for further in vitro and in vivo studies.

Soyghurt Potentially Controls the Level of sFlt1 and PLGF in Preeclampsia Maternal Serum-Induced Placental Trophoblast Cell in vitro.

Purpose: To observe the effect of soya yoghurt (Soyghurt), which is high in flavonoid substance, on the expression of preeclampsia biomarkers (sFLT-1 and PLGF) on preeclampsia serum-induced trophoblast primary cell culture isolated from placental tissue. Methods: The trophoblast primary culture was induced by preeclampsia serum (10%). The Soyghurt treatment was performed with 2.5%, 5%, and 7.5% Soyghurt supernatant concentrations in culture media. The expression of preeclampsia markers, sFLT-1 and PLGF, were evaluated using ELISA. Results: Expression of sFLT-1 on preeclampsia-induced cell culture treated with Soyghurt was significantly lowered compared to the untreated group (p<0.01). However, no significant difference was observed in the PLGF levels of all groups induced by preeclampsia serum (p>0.05). Conclusion: This study demonstrates the potential effect of Soyghurt's in balancing preeclampsia marker expression by inhibiting the expression of sFLT-1 in preeclampsia serum -induced trophoblast cells.

The role of chidamide in the treatment of B-cell non-Hodgkin lymphoma: An updated systematic review.

B-cell non-Hodgkin lymphoma (B-NHL) is a lymphoid malignancy derived from B-cells that remains difficult to treat. Moreover, relapses and refractory cases are common. Abnormalities in epigenetic mechanisms, such as imbalanced histone acetylation affecting certain genes, contribute to relapses and refractory cases. Chidamide (tucidinostat) is a novel histone deacetylase inhibitor that can reverse this epigenetic imbalance and has been approved for the treatment of T-cell malignancies. However, the use of chidamide for B-NHL remains limited, and the lack of relevant literature exacerbates this limitation. We conducted this review to summarize the anticancer activity of chidamide against B-NHL and its clinical applications to overcome drug resistance. This systematic review was conducted according to the PRISMA 2020 guidelines, using some keyword combinations from MEDLINE and EBSCO. The inclusion and exclusion criteria were also defined. Of the 131 records retrieved from databases, 16 were included in the review. Nine articles revealed that chidamide limited tumor progression by modifying the tumor microenvironment, stopping the cell cycle, inducing apoptosis and autophagy, and enhancing complement-dependent and antibody-dependent cell-mediated cytotoxicities.According to seven other studies, administering chidamide in combination with another existing therapeutic regimen may benefit not only patients with relapsed/refractory B-NHL, but also those with newly diagnosed B-NHL. Chidamide plays many important roles in limiting B-NHL progression through epigenetic modifications. Thus, combining chidamide with other anticancer drugs may be more beneficial for patients with newly diagnosed and relapsed/refractory B-NHL.

The Ethyl Acetate Fraction of Marine Sponge Stylissa carteri Induces Breast Cancer Cell Death via Upregulation of Mcl-1S: an In vitro Study.

OBJECTIVE: To evaluate the potency of the fraction of marine sponge Stylissa carteri in inducing cell death, inhibiting spheroid growth, and its impact on pro-apoptotic protein Mcl-1S in breast cancer cells. METHODS: Stylissa carteri were collected from Pramuka Island followed by ethanol extraction and ethyl acetate fractionation. To evaluate the cytotoxic effect of fraction, the HCC-1954, MDA MB 231, and MCF-7 cells were treated with the fraction of Stylissa carteri and MTT assay was then performed. The effect on spheroid growth was evaluated in HCC-1954 cells. The combined effect of the ethyl acetate fraction and paclitaxel were analyzed using combination index (CI) and immunoblotting on the pro-apoptotic protein Mcl-1S. Furthermore, compounds in this fraction were identified using GC-MS. RESULTS: Data showed that both the MDA MB 231 and HCC-1954 cells were interestingly more sensitive to the fraction as compared with MCF-7 cells. The IC50 of the ethyl acetate fraction on HCC-1954, MDA MB 231 and MCF-7 were 4.1 µg/ml, 3.9 µg/ml, and 123.8 µg/ml, respectively. In addition, the fraction triggered spheroid destruction within 10 days. The CI of paclitaxel and ethyl acetate fraction of Stylissa carteri were less than 0.52. Moreover, this combination induced upregulation of the Mcl-1S protein. Furthermore, some fatty acid-based structures were predicted as the major compounds in this fraction. CONCLUSION: The ethyl acetate fraction of Stylissa carteri induces cell death and spheroid destruction in aggressive breast cancer cells. It has a synergistic cytotoxic effect with paclitaxel on MDA MB 231 cell death and upregulates Mcl-1S protein.

Transcatheter Closure of Perimembranous Ventricular Septal Defect Using the Lifetech Konar-Multi Functional Occluder: Early to Midterm Results of the Indonesian Multicenter Study.

Background: The alternative device to close perimembranous ventricular septal defect (pmVSD) has been searched for better result, less complications and applicable for infants. However, the ideal device is still unavailable. We aimed to evaluate the effectiveness and outcome of transcatheter pmVSD closure using the KONAR-multi functional occluder (MFO). Methods: Clinical, procedural, follow-up data of pmVSD patients with symptom of heart failure or evidence of significant left to right shunt, growth failure, recurrent respiratory tract infection, and history of endocarditis who underwent transcatheter closure using the MFO were prospectively evaluated. Results: Between January 2016 and December 2017, there were complete records of 132 pmVSD children closed using MFO from eleven centers in Indonesia. The median of age was 4.5 (0.3-17.4) years; weight 14.8 (3.5-57) kg, defect size at the smallest part 3.4 (1.0-8.1) mm, flow ratio 1.6 (1.3-4.9), mean pulmonary artery pressure 18 (7-79) mmHg, fluoroscopy time 18 (3.8-91) and procedural time 75 (26-290) minutes. A retrograde approach was done in 41 (31%) patients. Procedures succeeded in first attempt in 126 (95.4%), failed in three and migration in three patients. Six of eight infants with congestive heart failure were closed successfully. Of 126 patients with successful VSD closure, 12 months follow-up were completed in all patients. The rate of complete occlusion at 1 month, 3 months, 6 months and 12 months after intervention were 95.2%, 97.6%, 99.2%, and 99.2%, respectively. New-onset aortic regurgitation and moderate tricuspid regurgitation developed only in five and three patients. Neither complete atrioventricular block, nor other complications occurred. Conclusion: Transcatheter closure of pmVSD using the MFO is safe, effective, and feasible in infants and children.

Thyroid disease and hypothyroidism are associated with poor COVID-19 outcomes: A systematic review, meta-analysis, and meta-regression.

BACKGROUND AND AIMS: Coronavirus disease (COVID-19) still becomes a global burden that affected people in different groups. The aim of this study was to evaluate the association between thyroid disease and the outcome of COVID-19 patients. METHOD: This was a meta-analysis study from articles obtained through a systematic literature search to investigate the relationship between thyroid disease and COVID-19 outcomes. Composite poor outcomes comprised of severity, mortality, intensive care unit (ICU) admission, and hospitalization. RESULTS: A total of 31339 patients from 21 studies included in this study. Thyroid disorder was associated with increased composite poor outcome (risk ratio (RR) 1.87 [95% confidence interval (CI) 1.53, 2.27], p < 0.001; I2 = 84%, p < 0.01), this included higher disease severity (RR 1.92 [1.40, 2.63], p < 0.05; I2 = 86%, p < 0.01), ICU admission (RR 1.61 [1.12, 2.32], p > 0.05; I2 = 32%, p < 0.05), mortality (RR 2.43 [1.44, 4.13], p < 0.05; I2 = 83%, p < 0.01), and hospitalization (RR 1.28 [1.17, 1.39], p < 0.05; I2 = 0%, p < 0.96). Meta-regression analysis indicated that age (p = 0.002) was a significant influence that affects the association. Also, the presence of unspecified thyroid disease (RR 1.91 [1.38, 2.65], p < 0.05; I2 = 81%, p < 0.01) and hypothyroidism (RR 1.90 [1.45, 2.55], p < 0.05; I2 = 85%, p < 0.01) during admission were associated with poor outcomes. CONCLUSION: Thyroid abnormalities increased the risk of COVID-19 composite poor outcomes and were influenced by the patient's age. Abnormal thyroid and hypothyroidism, but not hyperthyroidism, were associated with poor COVID-19 outcomes.

Monitoring Of High-Dose Methotrexate (Mtx)-Related Toxicity and Mtx Levels in Children with Acute Lymphoblastic Leukemia: A Pilot-Study in Indonesia.

The administration of high-dose methotrexate (HD-MTX) requires an accurate monitoring of blood MTX levels to determine the regimen of leucovorin rescue and urine alkalinization to prevent toxicity. However, it is technically and logistically challenging to screen patients routinely in limited-resource settings. This study aimed to evaluate blood MTX levels at 24- and 48-hours from start of infusion in relation to clinical toxicity in childhood ALL. METHODS: A prospective cohort study was conducted on 32 consecutive children with acute lymphoblastic leukemia (ALL) who had received at least one cycle of 1 g/m2 HD-MTX intravenous infusion as a part of consolidation treatment based on the 2013 Indonesian ALL Protocol. In total, 68 cycles were evaluated. Serum MTX concentrations were measured using enzyme immunoassay. MTX toxicity was categorized using common toxicity criteria (CTCAE) 3.0 version. The association between MTX level and clinical toxicity was assessed by non-parametric analysis. RESULTS: The 24-hours MTX level was median 29.8 ng/mL (0.065 µmol/L) (IQR 8.1-390.6) with a modest decrease in 48-hours MTX serum level in all cycles (median 28.3 ng/mL and 0.062 µmol/L; IQR 0.35-28.7; p <0.05). The two most common toxicities were hepatotoxicity (32.2%) and neutropenia (30.9%). Nephrotoxicity and febrile neutropenia occurred in 8.8% and 5.8% of patients, respectively, with low percentage of mucositis (4.3%) and thrombocytopenia (5.6%) recorded.  No statistically significant association was found between MTX levels and clinical toxicity, except for liver toxicity. CONCLUSION: Serum MTX levels at 24-hours and 48-hours are low, followed by only 4.4% grade III/IV hepatotoxicity and 26,4% grade III/IV neutropenia. There is no significant association between the clinical toxicity and MTX levels at the two points of measurement. An attempt to increase the MTX dose and/or to introduce a loading dose should be considered in subsequent ALL protocol as supported by further pharmacokinetic MTX studies in the Indonesian population.

The use of Janus Kinase inhibitors in hospitalized patients with COVID-19: Systematic review and meta-analysis.

BACKGROUND: The evidence of using JAK inhibitors among hospitalized patients with COVID-19 is conflicting. The systematic review and meta-analysis aimed to address the efficacy of Janus Kinase (JAK) Inhibitors in reducing risk of mortality among hospitalized patients with COVID-19. METHODS: Several electronic databases, including PubMed, EuropePMC, and the Cochrane Central Register of Controlled Trials, with relevant keywords "COVID-19″ AND ("JAK inhibitor" OR "Ruxolitinib" OR "Tofacitinib" OR "Fedratinib" OR "Baricitinib") AND ("Severe" OR "Mortality"), were used to perform a systematic literature search up to December 11, 2020. All studies pertinent to the predetermined eligibility criteria were included in the analysis. Our outcome of interest was all types of mortality, clinical improvement, and clinical deterioration. Dichotomous variables of our outcomes of interest were analyzed using Maentel-Haenszel formula to obtain odds ratios (ORs) and 95% confidence intervals (CI) with random-effects modeling regardless of heterogeneity. RESULTS: Five studies with a total of 1190 patients and were included in this systematic review and meta-analysis. The use of JAK inhibitors was associated with a reduced risk of mortality (OR 0.51, 95% CI 0.28-0.93, P = 0.02; I2: 7.8%, P = 0.354) and clinical improvement (OR 1.76, 95% CI 1.05-2.95, P = 0.032; I2: 26.4%, P = 0.253). The use of JAK inhibitors was not associated with a reduced risk of clinical deterioration (OR 0.58, 95% CI 0.28-1.19, P = 0.136; I2: 24.1%, P = 0.267). CONCLUSION: The use of JAK inhibitors was significantly associated with a reduced risk of mortality, and clinical improvement in hospitalized patients with COVID-19.

The Ethanol Extract of Marine Sponge Aaptos suberitoides Suppress Cell Viability, Cell Proliferation and Cell Migration in HER2-Positive Breast Cancer Cell Line.

OBJECTIVE: This study aimed to investigate the cytotoxicity, anti-proliferation and anti-migration effect of the ethanol extract of Aaptos suberitoides on trastuzumab-resistant HER2+ breast cancer cell line. METHODS: Aaptos suberitoides was collected from Tinjil Island, Banten, Indonesia, and was processed with maceration and ethanol extraction. HCC-1954 cells were treated with the ethanol extract and then followed by 3- [4, 5-dimethylthiazol-2-yl] -2.5 diphenyl tetrazolium bromide (MTT) assay to assess cytotoxicity, clonogenic assay and three-dimensional (3D) spheroid assay to evaluate anti-proliferative effect in two-dimensional and 3D model, respectively, and wound healing assay to determine anti-cell migration effect. Four parametric regression was used to analyse the IC50. RESULTS: This study revealed that the ethanol extract of Aaptos suberitoides suppressed cell viability in correlation with cell death induction. The IC50 values of the ethanol extract of Aaptos suberitoides using MTT assay and clonogenic assay were 12.0 ppm and 4.36 ppm, respectively. The extract demonstrated an inhibition effect on spheroid growth. In low concentration, the extract of Aaptos suberitoides inhibited cell migration. Furthermore, MS analysis showed that the most abundant compounds in this extract has molecular weight m/z 229.81 [M+H]+. CONCLUSION: This study revealed that the ethanol extract of Aaptos suberitoides demonstrates cytotoxicity, anti-proliferation and anti-migration effect as well as inhibition effect on three-dimensional spheroid growth in trastuzumab-resistant HER2+ breast cancer cell line.
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Bioactive Compounds in the Ethanol Extract of Marine Sponge Stylissa carteri Demonstrates Potential Anti-Cancer Activity in Breast Cancer Cells

Objective: Despite advanced treatment options available, drug resistance develops in breast cancer (BC) patients requiring novel effective drugs. Stylissa carteri, a marine sponge predominantly living in Indonesia territories, has not been extensively studied as anti-cancer. Therefore, this study targeted to assess the anti-tumor activity of the ethanol extract of S. carteri in BC cells. Methods: S. carteri was collected from Pramuka Island, at Kepulauan Seribu National Park, Jakarta, Indonesia and extracted using ethanol. Different BC cells including MDA MB 231, MDA MB 468, SKBR3, HCC-1954 and MCF-7 cells were treated with this extract for cytotoxic analysis using MTT assay. Spheroid growth assay and apoptosis assay were conducted in HCC-1954 cells. In addition, cell migration analysis and synergistic activity with doxorubicin or paclitaxel were conducted in MDA MB 231 cells. This extract was subjected also for GC-MS analysis. Results: The results show that ethanol extract of S. carteri demonstrated a cytotoxic activity in BC cells. The IC50 of this extract was lower 15 µg/ml in MDA MB 231, MDA MB 468, SKBR3, and HCC-1954 cells. Moreover, this extract inhibited spheroids growth and induced apoptosis in HCC-1954 cells. It inhibited cell migration and demonstrated a synergistic activity with doxorubicin or paclitaxel on triggering cell death in MDA MB 231 cells. Furthermore, GC-MS analysis indicated that this extract contained 1,2-Benzenediol, Dibutyl phthalate and 9,12-Octadecadienoic acid, ethyl ester. Conclusion: Our preliminary data indicate a potential anti-tumor activity of ethanol extract of S. carteri in breast cancer cells.

Pre-Osteoblasts Stimulate Migration of Breast Cancer Cells via the HGF/MET Pathway.

INTRODUCTION: The occurrence of skeletal metastases in cancer, e.g. breast cancer (BC), deteriorates patient life expectancy and quality-of-life. Current treatment options against tumor-associated bone disease are limited to anti-resorptive therapies and aimed towards palliation. There remains a lack of therapeutic approaches, which reverse or even prevent the development of bone metastases. Recent studies demonstrate that not only osteoclasts (OCs), but also osteoblasts (OBs) play a central role in the pathogenesis of skeletal metastases, partly by producing hepatocyte growth factor (HGF), which promotes tumor cell migration and seeding into the bone. OBs consist of a heterogeneous cell pool with respect to their maturation stage and function. Recent studies highlight the critical role of pre-OBs in hematopoiesis. Whether the development of bone metastases can be attributed to a particular OB maturation stage is currently unknown. METHODS AND RESULTS: Pre-OBs were generated from healthy donor (HD)-derived bone marrow stromal cells (BMSC) as well as the BMSC line KM105 and defined as ALPlow OPNlow RUNX2high OSX high CD166high. Conditioned media (CM) of pre-OBs, but not of undifferentiated cells or mature OBs, enhanced migration of metastatic BC cells. Importantly, HGF mRNA was significantly up-regulated in pre-OBs versus mature OBs, and CM of pre-OBs activated the MET signaling pathway. Highlighting a key role for HGF, CM from HGF-negative pre-OBs derived from the BMSC line HS27A did not support migration of BC cells. Genetically (siMET) or pharmacologically (INCB28060) targeting MET inhibited both HGF- and pre-OB CM- mediated BC cell migration. CONCLUSIONS: Our data demonstrate for the first time a role for pre-OBs in mediating HGF/MET- dependent migration of BC cells and strongly support the clinical evaluation of INCB28060 and other MET inhibitors to limit and/or prevent BC-associated bone metastases.

Mcl-1 confers protection of Her2-positive breast cancer cells to hypoxia: therapeutic implications.

BACKGROUND: Molecular mechanisms leading to the adaptation of breast cancer (BC) cells to hypoxia are largely unknown. The anti-apoptotic Bcl-2 family member myeloid cell leukemia-1 (Mcl-1) is frequently amplified in BC; and elevated Mcl-1 levels have been correlated with poor prognosis. Here we investigated the pathophysiologic role of Mcl-1 in Her2-positive BC cells under hypoxic conditions. METHODS: RNA interference and a novel small molecule inhibitor, EU-5346, were used to examine the role of Mcl-1 in Her2-positive BC cell lines and primary BC cells (sensitive or intrinsically resistant to Her2 inhibitors) under hypoxic conditions (using a hypoxic incubation chamber). Mechanisms-of-action were investigated by RT-PCR, mitochondrial isolation, as well as immunoprecipitation/blotting analysis, and microscopy. The specificity against Mcl-1 of the novel small molecule inhibitor EU5346 was verified in Mcl-1(Δ/null) versus Mcl-1(wt/wt) Murine Embryonic Fibroblasts (MEFs). Proliferation, survival, and spheroid formation were assessed in response to Mcl-1 and Her2 inhibition. RESULTS: We demonstrate for a strong correlation between high Mcl-1 protein levels and hypoxia, predominantly in Her2-positive BC cells. Surprisingly, genetic depletion of Mcl-1 decreased Her2 and Hif-1α levels followed by inhibition of BC cell survival. In contrast, Mcl-1 protein levels were not downregulated after genetic depletion of Her2 indicating a regulatory role of Mcl-1 upstream of Her2. Indeed, Mcl-1 and Her2 co-localize within the mitochondrial fraction and form a Mcl-1/Her2- protein complex. Similar to genetically targeting Mcl-1 the novel small molecule Mcl-1 inhibitor EU-5346 induced cell death and decreased spheroid formation in Her2-positive BC cells. Of interest, EU-5346 induced ubiquitination of Mcl-1- bound Her2 demonstrating a previously unknown role for Mcl-1 to stabilize Her2 protein levels. Importantly, targeting Mcl-1 was also active in Her2-positive BC cells resistant to Her2 inhibitors, including a brain-primed Her2-positive cell line. CONCLUSION: Our data demonstrate a critical role of Mcl-1 in Her2-positive BC cell survival under hypoxic conditions and provide the preclinical framework for the therapeutic use of novel Mcl-1- targeting agents to improve patient outcome in BC.

Targeting Mcl-1 for multiple myeloma (MM) therapy: drug-induced generation of Mcl-1 fragment Mcl-1(128-350) triggers MM cell death via c-Jun upregulation.

Myeloid cell leukemia-1 (Mcl-1, HGNC: 6943), a pro-survival member of the Bcl-2 family, plays a crucial role in Multiple Myeloma (MM) pathogenesis and drug resistance, thus representing a promising therapeutic target in MM. A novel strategy to inhibit Mcl-1 activity is the induction of ubiquitin-independent Mcl-1 degradation. Our own and other previous studies have demonstrated caspase-dependent generation of a 28kDa Mcl-1 fragment, Mcl-1(128-350), which inhibits MM cell proliferation and survival. Here, we show that similar to bortezomib, the novel proteasome inhibitors carfilzomib and ixazomib, as well as staurosporine and adaphostin, induce the generation of Mcl-1(128-350) in MM cells. Next, the molecular sequelae downstream of Mcl-1(128-350), which mediate its pro-apoptotic activity, were delineated. Surprisingly, we observed nuclear accumulation of drug-induced or exogenously overexpressed Mcl-1(128-350), followed by elevated mRNA and protein levels of c-Jun, as well as enhanced AP-1 reporter activity. Moreover, drug-induced AP-1 activity was blocked after introducing a point mutation into the highly conserved Mcl-1 caspase-cleavage site Asp127, but not Asp157. Consequently, drug-triggered cell death was significantly decreased in MM cells transfected with Mcl-1 D127A, but not with Mcl-1 D157A. Consistent with these data, treatment with bortezomib triggered c-Jun upregulation followed by apoptosis in Mcl-1(wt/wt), but not Mcl-1(Δ/null) murine embryonic fibroblasts (MEFs). Transfection of a plasmid carrying Mcl-1(wt) into Mcl-1(Δ/null) MEFs restored bortezomib-induced Mcl-1 fragmentation, c-Jun upregulation and AP-1 reporter activity. Finally, our data indicate that drug-induced generation of a pro-apoptotic Mcl-1 fragment followed by c-Jun upregulation may also be a novel therapeutic approach in other tumor entities.