👤 Hwang SG

Hepatic cancer is one of the main causes of cancer-related death worldwide. Cancer stem cells (CSCs) are a unique subset of cancer cells that promote tumour growth, maintenance, and therapeutic resistance, leading to recurrence. In the present work, the ability of a ruthenium complex containing 1,3-thiazolidine-2-thione (RCT), with the chemical formula [Ru(tzdt)(bipy)(dppb)]PF₆, to inhibit hepatic CSCs was explored in human hepatocellular carcinoma HepG2 cells. RCT exhibited potent cytotoxicity to solid and haematological cancer cell lines and reduced the clonogenic potential, CD133⁺ and CD44^high cell percentages and tumour spheroid growth of HepG2 cells. RCT also inhibited cell motility, as observed in the wound healing assay and transwell cell migration assay. RCT reduced the levels of Akt1, phospho-Akt (Ser473), phospho-Akt (Thr308), phospho-mTOR (Ser2448), and phospho-S6 (Ser235/Ser236) in HepG2 cells, indicating that interfering with Akt/mTOR signalling is a mechanism of action of RCT. The levels of active caspase-3 and cleaved PARP (Asp214) were increased in RCT-treated HepG2 cells, indicating the induction of apoptotic cell death. In addition, RCT modulated the autophagy markers LC3B and p62/SQSTM1 in HepG2 cells and increased mitophagy in a mt-Keima-transfected mouse embryonic fibroblast (MEF) cell model, and RCT-induced cytotoxicity was partially prevented by autophagy inhibitors. Furthermore, mutant Atg5^-/- MEFs and PentaKO HeLa cells (human cervical adenocarcinoma with five autophagy receptor knockouts) were less sensitive to RCT cytotoxicity than their parental cell lines, indicating that RCT induces autophagy-mediated cell death. Taken together, these data indicate that RCT is a novel potential anti-liver cancer drug with a suppressive effect on CSCs. Show less

We disclose novel amphiphilic ruthenium and osmium complexes that auto-assemble into nanomedicines with potent antiproliferative activity by inhibition of mitochondrial respiration. The self-assembling units were rationally designed from the [M(p-cymene)(1,10-phenanthroline)Cl]PF₆ motif (where M is either Ru^II or Os^II) with an appended C₁₆ fatty chain to achieve high cellular activity, nano-assembling and mitochondrial targeting. These amphiphilic complexes block cell proliferation at the sub-micromolar range and are particularly potent towards glioblastoma neurospheres made from patient-derived cancer stem cells. A subcutaneous mouse model using these glioblastoma stem cells highlights one of our C₁₆ Os^II nanomedicines as highly successful in vivo. Mechanistically, we show that they act as metabolic poisons, strongly impairing mitochondrial respiration, corroborated by morphological changes and damage to the mitochondria. A genetic strategy based on RNAi gave further insight on the potential involvement of microtubules as part of the induced cell death. In parallel, we examined the structural properties of these new amphiphilic metal-based constructs, their reactivity and mechanism. Show less

Reactive oxygen species (ROS) are well known to be involved in oncogene-mediated cellular transformation. However, the regulatory mechanisms underlying ROS generation in oncogene-transformed cells are unclear. In the present study, we found that oncogenic K-Ras induces ROS generation through activation of NADPH oxidase 1 (NOX1), which is a critical regulator for the K-Ras-induced cellular transformation. NOX1 was activated by K-Ras-dependent translocation of p47(phox), a subunit of NOX1 to plasma membrane. Of note, PKCδ, when it was activated by PDPK1, directly bound to the SH3-N domain of p47(phox) and catalyzed the phosphorylation on Ser348 and Ser473 residues of p47(phox) C-terminal in a K-Ras-dependent manner, finally leading to its membrane translocation. Notably, oncogenic K-Ras activated all MAPKs (JNK, ERK and p38); however, only p38 was involved in p47(phox)-NOX1-dependent ROS generation and consequent transformation. Importantly, K-Ras-induced activation of p38 led to an activation of PDPK1, which then signals through PKCδ, p47(phox) and NOX1. In agreement with the mechanism, inhibition of p38, PDPK1, PKCδ, p47(phox) or NOX1 effectively blocked K-Ras-induced ROS generation, anchorage-independent colony formation and tumor formation. Taken together, our findings demonstrated that oncogenic K-Ras activates the signaling cascade p38/PDPK1/PKCδ/p47(phox)/NOX1 for ROS generation and consequent malignant cellular transformation. Show less

Platinum resistance is a major limitation in the treatment of advanced non-small-cell lung cancer (NSCLC). Reduced intracellular drug accumulation is one of the most consistently identified features of platinum-resistant cell lines, but clinical data are limited. We assessed the effects of tissue platinum concentrations on response and survival in NSCLC. Show less