Loss of PTEN-Induced Kinase 1 Regulates Oncogenic Ras-Driven Tumor Growth By Inhibiting Mitochondrial Fission

ARK5 enhances cell survival associated with mitochondrial morphological dynamics from fusion to fission in human multiple myeloma cells

5' adenosine monophosphate-activated protein kinase-related kinase 5 (ARK5) is involved in mitochondrial ATP production and associated with poor prognosis of multiple myeloma (MM). However, the molecular mechanisms of ARK5 in MM remain largely unknown. This study examined the pathogenic role of ARK5 in mitochondria by using genetically modified isogenic cell clones with or without ARK5 in human myeloma cell lines, KMS-11 and Sachi, which overexpress ARK5. The biallelic knockout of ARK5 (ARK5-KO) inhibited cell proliferation, colony formation, and migration with increased apoptosis. Mitochondrial fusion was enhanced in ARK5-KO cells, unlike in ARK5 wild-type (ARK5-WT) cells, which exhibited increased mitochondrial fission. Furthermore, ARK5-KO cells demonstrated a lower phosphorylated dynamin-related protein 1 at serine 616, higher protein expression of mitofusin-1 (MFN1) and MFN2, optic atrophy 1 with a lower level of ATP, and higher levels of lactate and reactive oxygen species than ARK5-WT cells. Our findings suggest that ARK5-enhanced myeloma cells can survive associated mitochondrial fission and activity. This study first revealed the relationship between ARK5 and mitochondrial morphological dynamics. Thus, our outcomes show novel aspects of mitochondrial biology of ARK5, which can afford a more advanced treatment approach for unfavorable MM expressing ARK5.

Kinase signalling adaptation supports dysfunctional mitochondria in disease

Mitochondria form a critical control nexus which are essential for maintaining correct tissue homeostasis. An increasing number of studies have identified dysregulation of mitochondria as a driver in cancer. However, which pathways support and promote this adapted mitochondrial function? A key hallmark of cancer is perturbation of kinase signalling pathways. These pathways include mitogen activated protein kinases (MAPK), lipid secondary messenger networks, cyclic-AMP-activated (cAMP)/AMP-activated kinases (AMPK), and Ca2+/calmodulin-dependent protein kinase (CaMK) networks. These signalling pathways have multiple substrates which support initiation and persistence of cancer. Many of these are involved in the regulation of mitochondrial morphology, mitochondrial apoptosis, mitochondrial calcium homeostasis, mitochondrial associated membranes (MAMs), and retrograde ROS signalling. This review will aim to both explore how kinase signalling integrates with these critical mitochondrial pathways and highlight how these systems can be usurped to support the development of disease. In addition, we will identify areas which require further investigation to fully understand the complexities of these regulatory interactions. Overall, this review will emphasize how studying the interaction between kinase signalling and mitochondria improves our understanding of mitochondrial homeostasis and can yield novel therapeutic targets to treat disease.

DDTC Suppresses Ovarian Cancer Development via the PI3K/AKT/mTOR Signaling Pathway

In prior research, 6,12-diphenyl-3,9-diazatetraasterane-1, 5, 7, 11-tetracarboxylate (DDTC) has been shown to be an effective inhibitor of the growth of the SKOV3 and A2780 ovarian cancer (OC) cell lines. Flow cytometry analyses indicated that DDTC was able to suppress P-CNA expression at the protein level within OC cells, while RNA-seq indicated that DDTC treatment was associated with marked changes in gene expression profiles within A2780 cells. Molecular docking analyses suggested that DDTC has the potential to readily dock with key signaling proteins including PI3K, AKT, and mTOR. In line with these findings, DDTC treatment inhibited the growth of xenograft tumors in a mouse model system. Such treatment was also associated with reduced p-PI3K/PI3K, p-AKT/AKT, p-mTOR/mTOR, and CyclinD1 (CCND1) expressions and with the increased expression of PTEN in vitro and in vivo. Together, these results suggest that DDTC is capable of readily inhibiting OC development at least in part via targeting and modulating signaling via the PI3K/AKT/mTOR axis.