Table 2.

Development of small molecules targeting the core clock machinery

Target	Drugs	Mechanism of actions	Effects	Experimental model	Pathological context	Refs.
REV-ERBα/β	GSK4112	REV-ERBα/β agonist	–Inhibition of cell-proliferation, by preventing transition from G1 to S phase. –Increased expression of the proliferation inhibitor (p27) and suppression of the expression of the proliferation-promoting factor Cyclin D and β-catenin. –Induction of apoptosis, with an increase in Bax mRNA levels and Caspase-3 and a decrease in Bcl-2 levels.	Mouse 3T3-L1 adipocytes	Obesity	148
			–Reduction of ALT and AST plasmatic levels. –Improvement of liver condition and the survival rate in Jo2-insulted mice. –Inhibition of hepatocyte apoptosis, with a reduction of caspase-3 and caspase-8 activities.	Wild-type and Jo2 treated C57BL/6 mice	Liver injury	149
			–Inhibition of LPS-induced phosphorylation of IκK, thereby blocking p65 nuclear translocation and suppressing the expression of proinflammatory cytokines, such as IL-6 and TNFα.	BV2 cells and Male C57BL/6 mice	Neuro-inflammation; neurodegenerative diseases; psychiatric disorders	150
			–Protection of ventral midbrain neurons from LPS-induced microglial activation-induced damage.
	SR9001 SR9009	REV-ERBα/β agonists	–Reduction of the expression of GSC markers (e.g. OLIG2 and SOX2), supporting negative transcriptional regulation of key GSC targets. –Decreased GSC cell proliferation and the expression of genes involved in glycolysis, TCA cycle, and lipid metabolism.	Derived Human Glioblastoma Stem Cells	Glioblastoma	145
			–Reduction of GBM growth. –Induction of apoptosis and downregulation of autophagic genes (Ulk3- Ulk1, Beclin1, and Atg7).	C57BL/6	Glioblastoma	137
			–Increase in apoptosis in NRAS-induced naevi and repression of autophagic gene expression (Ulk3, Ulk1, Beclin1, and Atg7).	C57BL/6 and Tyr-NrasQ61K mice	Melanoma, NRAS-induced naevi	137
	SR8278	REV-ERBα/β antagonist	–Improvement of microglial uptake of fibrillar amyloid-β (fAβ1‐42) –Microglia polarization toward a phagocytic M2‐like phenotype with increased P2Y12 receptor expression, thereby enabling the phagocytosis of Aβ aggregates.	Murine‐immortalized microglial BV‐2 cells 5XFAD and REV‐ERBα knockout mice	Alzheimer’s disease	151
			–Improvement of renal condition, by decreasing renal damage and cell death. –Diminution in renal malondialdehyde, iron levels and mitochondrial damage. –Increase in renal GSH and Gpx4 levels.	Wild-type C57BL/6 mice treated with folic acid	Acute kidney injury	152
	ARN5187	Dual inhibitory activity toward both REV-ERBs and autophagy	–Disruption of lysosomal function, blockade of autophagy at the late stage, and reduction of cancer cell viability. –Inhibition of REV-ERB mediated transcriptional regulation.	Breast cancer BT-474 cells	Breast cancer	153
ROR	Nobiletin	RORs agonist	–Improvement of strengthening circadian amplitude, causing an enhanced efficiency in physiological performance, greater stimuli range and sensitized response. –Reduction of body weight in WT mice fed with high-fat diet thanks to a reduction in fat mass and white adipose cell size. –Improvement of oxygen consumption with a switch from lipid-biased metabolism to a more balanced contribution from all major macronutrients. –Improvement in lipid and glucose metabolism, with a reduction in plasmatic level of insulin, total triglyceride and cholesterol.	Diet-induced obesity (DIO) mouse model using both WT and clock-disrupted ClockΔ19/Δ19 mice	Metabolic syndrome (obesity)	154
			–Promotion of healthy aging in metabolically stressed mammals. –Increase in the activation of MRCs genes, leading to an improvement of mitochondrial function (i.e. increase of ATP production and reduction of ROS levels).	C57BL/6 mice and C2C12 myoblast cells	Aging and metabolic syndrome	155
	SR1001	RORγt inverse agonist	–Reduction of retinal inflammation in diabetes. –Reduction of IL-17, TNF-α and VEGF serum levels. –Reduction of leukostasis. –Decrease in diabetic degenerative capillaries.	C57BL/6 mice WT and treated with STZ	Diabetes	156
			–Slowdown the onset and clinical severity of EAE. –Reduction of IL-17, IL-21 and IL-22 mRNA levels. –Reduction in T CD4+ cells population.	Wild-type and EAE C57BL/6 J; Hep-G2 cells	Autoimmune diseases (multiple sclerosis)	139
			–Reduction of IL-17A and IL-17F mRNA levels in mouse blood cells and prostate tissues. –Reduction of proliferation, angiogenesis and inflammatory cell infiltration, as well an increase in apoptosis in mouse model of prostate cancer.	Pten-null mice	Prostate cancer	157
	SR3335	RORα selective partial inverse agonist	–Inhibition of RORα target genes expression in HepG2 involved in hepatic gluconeogenesis. –Reduction of glucose plasmatic levels in mouse model.	Diet induced obese (DIO) C57BL/6 mice and HepG2 cells	Diabetes	158
			–Reduction of ILC2 cell population proliferation. –Inhibition of rynovirus-induced mucus metaplasia in immature mice. –Reduction of IL-13 and mucus-related mRNA levels.	BALB/c mice affected by rynovirus	Respiratory disease (asthma)	159
	SR1078	RORs agonist	–Reduction of repetitive behavior, associated with autism. –Increased expression of autism-associated RORα target genes in mouse brain.	BTBR T + Itpr3tf/J (BTBR)	Autism	160
			–Reduction of aerobic glycolysis and down-regulation of biosynthetic pathways in vitro. –Reduction of PDK2 mRNA levels and inhibition of the phosphorylation of pyruvate dehydrogenase. –Reduction of proliferation in hepatoma in vitro and in a xenograft model in vivo.	Hepatoma cell lines and n a xenograft model in vivo	Hepatoma	161
	Digoxine and derivates	RORγ inverse agonist	–Inhibition of IL-17 expression in human CD4+ T cells. –Reduction of IL-17a protein levels in naïve mouse CD4+ T cells.	Mouse and human CD4+ T cell culture	Inflammatory and autoimmune disease.	141
			–Reduction of the arthritic score and arthritis incidence. –Histological analyses showed a reduction in inflammatory cell infiltration and cartilage loss in mouse ankles. –Decrease in the expression of proinflammatory cytokines. –Reduction of the number of Th17 and increase of Treg population in mice with collagen-induced arthritis.	DBA/1J mice treated with bovine type II collagen and CD4+ T cells obtained from spleen of DBA/1J mice	Autoimmune arthritis	162
			–Reduction of Th17 cells in PBMCs. –Decrease in IL-1β, IL-6, IL-17, and IL-23 protein levels in supernatant of digoxin treated PBMCs.	PBMCs of RA patients	Rheumatoid arthritis	163
	SR2211	RORγ inverse agonist	–Inhibition in growth and proliferation of prostate cancer cells. –Promotion of apoptosis.	Doxorubicin-resistant prostate cancer C4-2B cells	Prostate cancer	164
			–Reduction in the expression and production of inflammatory cytokines in Th17 cells. –Reduction of LPS-driven IL-1β, IL-6, and TNFα expression in vitro. –Reduction of joint inflammation in mice with CIA.	DBA/1 J mice and Th17 cells and RAW 264.7 cells	Collagen-induced arthritis	165
CRY1/2	KL001	Stabilization of CRYs by inhibiting FBXL3-mediated ubiquitination and degradation of CRY proteins	–Significantly enhanced glucose clearance in a dose-dependent manner. –Reduction of fasting blood glucose.	db/db mouse model of diabetes and (DIO) C57BL/6J mouse model	Diabetes	142,143
			–Inhibition of glucagon-dependent expression of PCK1 and G6pc genes without influence their basal expression. –Specific inhibition of glucagon-mediated activation of glucose production.	Primary hepatocytes prepared at ZT9-11 from fed mice (C57BL/6)		144
			–Decrease in OLIG2 and SOX2 mRNA levels. –Inhibition GSC proliferation due to the increase in CRY1 overexpression, leading to a decrease in Myc expression.	Human GSCs and NSG immunocompromised mice	Glioblastoma	145
	SHP656	CRYs stabilizers	–Reduction of GSC cell number –Increase in survival of mice bearing two different patient-derived GSCs	Human GSCs and NSG immunocompromised mice	Glioblastoma	145
	KS15	CRYs inhibitor	–Increase in Per2 and REV-ERBα expression and reduction of BMAL1 mRNA levels in MCF-7 cells. –Reduction of Cyclin D1, c-Myc e Bcl-2 mRNA and protein levels and increase in p53, Bax, and Wee1 levels, thus suggesting the ability of compound to inhibit cell cycle. –Reduction of proliferation in MCF-7 cells. –Improvement of chemosensitivity.	MCF-7 cells	Breast cancer	166
CK1	IC261	CK1δ/ε inhibitor	–Inhibition of HCC with an accumulation of cells in G2/M phase. –Increase in the number of apoptotic cells and increase in cleaved-PARP protein levels. –Inhibition of tumor growth in mice bearing HCC tumor xenografts –Reduction in both tumor volume and weight.	HCC cell lines and BALB/c nude mice bearing HCC tumor xenografts	Hepatocellular carcinoma	167
	PF-670462	CK1ε and CK1δ Inhibitor	–Reduction in chemotaxis, invasion and communication with stromal cells in primary CLL cells and in all major subtypes of CLL. –Decrease in the leukemic cell’s accumulation in the peripheral blood and spleen. –Improvement of life expectancy of mice affected by CLL.	Primary cells isolated from peripheral blood of CLL patients and Eµ-TCL1 mouse model	Chronic lymphocytic leukemia	168
			–Normalization of hippocampal proteomic alterations (e.g. proteins involved in synaptic plasticity, cytoskeletal organization, mitochondrial function and elaboration of amyloid precursor protein) associated with AD-like pathology. –Improvement of cognitive disturbances (increase of memory and reduction of anxiety) associated with AD. –Restoration of circadian rhythms.	3xTg-AD Mice	Alzheimer’s Disease	169

BAX Bcl-2 associated X, Bcl-2 B-cell lymphoma 2, ALT alanine aminotransferase, AST aspartate transaminase, Jo2 anti-fas antibody, LPS lipopolysaccharide, NF-κB nuclear factor kappa B, IκK inhibitor of NF-κB alpha kinase, IL-6 interleukin 6, TNFα tumor necrosis factor α, GSC glioblastoma stem cells, OLIG2 oligodendrocyte lineage transcription factor 2, SOX2 SRY-box transcription factor 2, TCA tricarboxylic acid, GBM glioblastoma, Ulk3-Ulk1 unc-51 like kinase 3-1, Atg7 autophagy related 7, NRAS NRAS proto-oncogene, GTPase, fAβ_1-42 fibrillar amyloid-beta, GSH glutathione, Gpx4 glutathione peroxidase 4, DIO diet-induced obesity, MRCs mitochondrial respiratory chain complexes, ATP adenosine triphosphate, ROS reactive oxygen species, IL-17 interleukin 17, VEGF vascular-endothelial growth factor, STZ streptozotocin, IL-21 interleukin 21, IL-22 interleukin 22, EAE experimental autoimmune encephalomyelitis, ILC2 innate lymphoid type-2 cells, RV rinovirus, IL-13 interleukin 13, Muc5ac mucin 5AC, oligomeric mucus/gel-forming, BTBR mouse model of autism spectrum disorders, A2bp1 ataxin 2-binding protein 1, Cyp19a cytochrome P450 aromatase genes, ITPR1 inositol 1,4,5-trisphosphate receptor type 1, PDK2 pyruvate dehydrogenase kinase 2, IL-1 β interleukin 1-β, IL-6 interleukin 6, IL-23 interleukin-23, CIA mouse collagen induced arthritis, PBMCs peripheral blood mononuclear cells, RA rheumatoid arthritis, CIA collagen-induced arthritis, PCK1 phosphoenolpyruvate carboxykinase 1, G6pc glucose-6-phosphatase catalytic subunit, SCN suprachiasmatic nucleus, GSK3 glycogen synthase kinase-3, HCC hepatocellular carcinoma, CLL chronic lymphocytic leukemia, AD Alzheimer’s disease (AD)