Targeting CaMKK2 Inhibits Actin Cytoskeletal Assembly to Suppress Cancer Metastasis

Abstract

Triple-negative breast cancers (TNBCs) tend to become invasive and metastatic at early stages in their development. Despite some treatment successes in early stage localized TNBC, the rate of distant recurrence remains high, and long-term survival outcomes remain poor. In a search for new therapeutic targets for this disease, we observed that elevated expression of the serine/threonine kinase calcium/calmodulin (CaM)-dependent protein kinase kinase 2 (CaMKK2) is highly correlated with tumor invasiveness. In validation studies, genetic disruption of CaMKK2 expression or inhibition of its activity with small molecule inhibitors disrupted spontaneous metastatic outgrowth from primary tumors in murine xenograft models of TNBC. High-grade serous ovarian cancer (HGSOC), a high-risk, poor prognosis ovarian cancer subtype, shares many features with TNBC, and CaMKK2 inhibition effectively blocked metastatic progression in a validated xenograft model of this disease. Mechanistically, CaMKK2 increased the expression of the phosphodiesterase PDE1A which hydrolyzed cyclic guanosine monophosphate (cGMP) to decrease the cGMP-dependent activity of protein kinase G1 (PKG1). Inhibition of PKG1 resulted in decreased phosphorylation of vasodilator stimulated phosphoprotein (VASP), which in its hypophosphorylated state binds to and regulates F-actin assembly to facilitate cell movement. Together, these findings establish a targetable CaMKK2-PDE1A-PKG1-VASP signaling pathway that controls cancer cell motility and metastasis by impacting the actin cytoskeleton. Further, it identifies CaMKK2 as a potential therapeutic target that can be exploited to restrict tumor invasiveness in patients diagnosed with early-stage TNBC or localized HGSOC.

Dysregulated Cyclic Nucleotide Metabolism in Alcohol-Associated Steatohepatitis: Implications for Novel Targeted Therapies

“…Our recent work further demonstrated that PDE4D enzymes are expressed in activated HSCs in human and mouse livers and play a role in promoting cytoskeleton remodeling and HSC migration [58]. Notably, PDE1a has also been shown to regulate cell motility and the migration of cancer cells via cGMP/PKG [59]. Relevant to ALD, our studies identified the PDE4B-dependent downregulation of cAMP signaling as a pathogenic player in exaggerated responses of monocytes/macrophages to endotoxin on ALD [21,52].…”

EP4-induced mitochondrial localization and cell migration mediated by CALML6 in human oral squamous cell carcinoma

“…EP4 and CaMKK2 are known to correlate with the progression and survival rates in cancers such as vulvar cancer and breast cancer 43 , 44 . To the best of our knowledge, there have been no reports in oral cancer linking EP4, CaMKK2, or CALML6 with cancer progression or survival rates, indicating a need for further investigation (Supplementary Fig.…”

PTBP1 mediates Sertoli cell actin cytoskeleton organization by regulating alternative splicing of actin regulators

“…It is localized at the ES and has been reported to interact with tight junction proteins such as ZO1 (56), but its role in regulating actin assembly in the ES is unknown. CAMKK2 is a kinase that regulates actin assembly to guide cell adhesion, migration, and morphogenesis during tissue homeostasis and cancer metastasis (57)(58)(59)(60). PPP1R9A (also known as neural-specific F-actin-binding protein, NEURABIN1) is a kinase that binds to Factin to promote neurite formation and synaptic transmission (61)(62)(63).…”

“…We thus compared our data with published Sertoli cell-expressing genes (53,54), and identified 27 Sertoli cellenriched genes that are alternatively spliced upon PTBP1 deficiency (Supplementary Table 6). Strikingly, 8 of them (Espn, Tnik, Gm14569, Ppp1r9a, Appl2, Rab11fip3, Phactr2, and Camkk2) were reported to be functionally required for actin cytoskeleton organization (18,(55)(56)(57)(58)(59)(60)(61)(62)(63)(64). Except for Espn, splicing of more than one exon of each gene was affected by PTBP1 deletion, either in exon skipping or mutually exclusive AS (Figure 4A).…”