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/nullversus 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.

Objective: Despite advanced treatment options available, drug resistance develops in breast cancer (BC) patientsrequiring novel effective drugs. Stylissa carteri, a marine sponge predominantly living in Indonesia territories, hasnot been extensively studied as anti-cancer. Therefore, this study targeted to assess the anti-tumor activity of theethanol extract of S. carteri in BC cells. Methods: S. carteri was collected from Pramuka Island, at Kepulauan SeribuNational Park, Jakarta, Indonesia and extracted using ethanol. Different BC cells including MDA MB 231, MDAMB 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 andsynergistic activity with doxorubicin or paclitaxel were conducted in MDA MB 231 cells. This extract was subjectedalso for GC-MS analysis. Results: The results show that ethanol extract of S. carteri demonstrated a cytotoxic activityin BC cells. The IC50 of this extract was lower 15 μg/ml in MDA MB 231, MDA MB 468, SKBR3, and HCC-1954cells. Moreover, this extract inhibited spheroids growth and induced apoptosis in HCC-1954 cells. It inhibited cellmigration and demonstrated a synergistic activity with doxorubicin or paclitaxel on triggering cell death in MDA MB231 cells. Furthermore, GC-MS analysis indicated that this extract contained 1,2-Benzenediol, Dibutyl phthalate and9,12-Octadecadienoic acid, ethyl ester. Conclusion: Our preliminary data indicate a potential anti-tumor activity ofethanol extract of S. carteri in breast cancer cells.

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). 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. 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. Transcatheter closure of pmVSD using the MFO is safe, effective, and feasible in infants and children.