Ligustilide, A Novel Senolytic Compound Isolated from the Roots of Angelica Acutiloba

Senescent cells accumulate with age and contribute to age-related diseases and organ dysfunctions. Early evidence suggests that removal of senescent cells using senolytic drugs improves the aging phenotype in mice and may improve the health of individuals with chronic diseases. Signs of skin aging, including wrinkles, and sagging, occur largely due to the accumulation of senescent fibroblasts within the dermis; However, there is currently no skin treatment that eliminates senescent cells. In this study, human fibroblasts subjected to replicative aging and ionizing radiation exposure are used to screen plant extracts for potential senescent cell-destructive and/or senescent cell-forming activities. Angelica acutiloba-a traditional Chinese herbal medicine-selectively kills senescent cells without affecting the proliferating cells. Among the major components of this herb, ligustilide shows promising senescent cell-destructive properties, and selectively eliminates senescent cells by inducing an apoptosis. Moreover, ligustilide markedly inhibits senescence-associated secretory phenotypes. Administration of ligustilide to mouse skin eliminates senescent cells and increases dermal collagen density and subcutaneous adipose tissue content; it selectively promotes death of senescent cells without affecting non-senescent cells. These results provide evidence that a natural compound-ligustilide-may exhibit therapeutic effects on the skin aging phenotype by specifically inducing apoptosis in senescent cells.

Protein-Bound Uremic Toxins in Senescence and Kidney Fibrosis

Chronic kidney disease (CKD) is a progressive condition of kidney dysfunction due to diverse causes of injury. In healthy kidneys, protein-bound uremic toxins (PBUTs) are cleared from the systemic circulation by proximal tubule cells through the concerted action of plasma membrane transporters that facilitate their urinary excretion, but the endogenous metabolites are hardly removed with kidney dysfunction and may contribute to CKD progression. Accumulating evidence suggests that senescence of kidney tubule cells influences kidney fibrosis, the common endpoint for CKD with an excessive accumulation of extracellular matrix (ECM). Senescence is a special state of cells characterized by permanent cell cycle arrest and limitation of proliferation, which promotes fibrosis by releasing senescence-associated secretory phenotype (SASP) factors. The accumulation of PBUTs in CKD causes oxidative stress and increases the production of inflammatory (SASP) factors that could trigger fibrosis. Recent studies gave some clues that PBUTs may also promote senescence in kidney tubular cells. This review provides an overview on how senescence contributes to CKD, the involvement of PBUTs in this process, and how kidney senescence can be studied. Finally, some suggestions for future therapeutic options for CKD while targeting senescence are given.

A Human Conditionally Immortalized Proximal Tubule Epithelial Cell Line as a Novel Model for Studying Senescence and Response to Senolytics

Accumulating evidence suggests that senescence of kidney tubule epithelial cells leads to fibrosis. These cells secrete senescence-associated secretory phenotype (SASP) factors that are involved in diverse signaling pathways, influencing kidney fibrosis. Here, we investigated whether our previously established conditionally immortalized proximal tubule epithelial cell line overexpressing the organic anion transporter 1 (ciPTEC-OAT1) can be used as a valid in vitro model to study kidney senescence and senolytics response. CiPTEC-OAT1 proliferates rapidly at 33°C and exhibits a “senescence-like” arrest at 37°C, most likely due to suppression of SV40T expression and subsequent reactivation of the p53 and Rb pathways. To understand how permissive (33°C) and non-permissive (37°C) temperatures of the cell culture affect the senescence phenotype, we cultured ciPTEC-OAT1 for up to 12 days and evaluated the apoptosis and SASP markers. Day 0 in both groups is considered as the non-senescence group (control). Further, the potential of navitoclax, dasatinib, quercetin, and the combination of the latter two to clear senescent cells was evaluated. Maturation of ciPTEC-OAT1 at non-permissive temperature affected mRNA and protein levels of senescence markers. A remarkable upregulation in p21 gene expression was found in the non-permissive temperature group, whereas expression of Lamin B1 decreased significantly. SASP factors, including PAI-1A, IL-1β, CTGF, and IL-6 were upregulated, but no significant difference in Bcl-2 and Bcl-xl were found in the non-permissive temperature group. After culturing ciPTEC-OAT1 up to 12 days, cells in the non-permissive temperature group showed an upregulation in the apoptosis-associated proteins Bcl-2, BID, and Bax, and a downregulation in Mcl-1, Bad, Bak, and Bim at various time points. Further, Bcl-xl, Puma, Caspase 3, Caspase 7, and Caspase 9 showed initial upregulations followed by downregulations at later time points. The loss of Lamin B1, upregulation of SA-β-gal expression and increase in its activity, upregulation of p21 levels and downregulation of p53, along with the upregulation of SASP factors, confirmed that maturation at 37°C promotes senescence features. Finally, the senolytics response was evaluated by testing cell viability following exposure to senolytics, to which cells appeared dose-dependently sensitive. Navitoclax was most effective in eliminating senescent cells. In conclusion, culturing ciPTEC-OAT1 at 37°C induces a senescence phenotype characterized by increased expression of cell cycle arrest and anti-apoptosis markers, SASP factors, and responsiveness to senolytics treatment. Therefore, ciPTEC-OAT1 represents a valid model for studying kidney senescence by simply adjusting culture conditions.

Photoacoustic imaging in evaluating early intestinal ischemia injury and reperfusion injury in rat models

Background

It remains a challenge to distinguish whether the damaged intestine is viable in treating acute mesenteric ischemia. In this study, photoacoustic imaging (PAI) was used to observe intestinal tissue viability after ischemia and reperfusion injury in rats.

Methods

An in vivo study was conducted using forty male SD rats, which were randomly divided into a sham-operated (SO) group, a 1 h ischemia group, a 2 h ischemia group, and an ischemia-reperfusion (I/R) group with 10 rats in each group. In the ischemia group, the superior mesenteric artery (SMA) was isolated and clamped for 1 and 2 h, respectively, and in the I/R group, after ischemia for 1 h, the clamp was removed and reperfused for 1 h. The same time interval was used in the SO group. Immediately after establishing the animal model, a PAI examination was performed, and the small intestine was collected for histopathology.

Results

The levels of PAI parameters Hb, HbR, MAP 760, and MAP 840 were increased to different degrees in the ischemia groups, especially in the 2 h ischemia group, compared with the SO group (P<0.05), and with prolongation of the ischemia time, the injury was aggravated. All PAI signal levels except HbO in the I/R group were higher than those in the control group, and the increased range differed, especially in Hb and MAP 840. Using western blot, compared with the SO group, the BAX increased significantly in the 2 h ischemia group (P<0.05), and Caspase-3 in the experimental group was significantly higher than in the SO group (P<0.05). The level of HIF-1α increased in the 2 h ischemia group and I/R group (P<0.05), and TUNEL staining showed that the number of positive apoptotic nuclei in the 2 h ischemia group was significantly higher than in the SO group (P<0.05). Hematoxylin-eosin (HE) staining showed that ischemia for 2 hours was the most serious, with obvious mucosal damage, extensive epithelial injury, and bleeding.

Conclusions

PAI can be used as an effective tool to detect acute intestinal ischemia injury and quantitatively evaluate tissue viability.

Another structural correction for 1-oxo-1H-phenalene-2,3-dicarbonitriles: Synthesis of a potent BCL-2 inhibiting 7-phenoxy derivative

Aromatic scaffolds are an important part of biologically active compounds and molecular probes used to study biochemical pathways and the involved targeted proteins of interest. 1-Oxo-1H-phenalene-2,3-dicarbonitrile-based compounds have been described as inhibitors of the BCL-2 family of proteins, and this core structure represents numerous possibilities for modifications that could lead to improved inhibitory potencies. Many studies demonstrated intriguing characteristics of these compounds in terms of reactivity and, interestingly, some contradictory literature reports appeared about reaction outcomes to synthesize them. Here, we initially provide a condensed overview of transformations performed on the phenalene scaffold, followed by the resynthesis of a 6-phenoxy-substituted derivative. We show that the initial determination of this particular structure was wrong and provide two-dimensional nuclear magnetic resonance (NMR) evidence to assign the structure properly. When preparing new derivatives using the same synthetic route, we observed 6- and 7-substituted regioisomers. After confirming their structures by NMR experiments, the ability of these compounds to inhibit BCL-2 was evaluated. The most potent 1-oxo-1H-phenalene-2,3-dicarbonitrile derivatives inhibited BCL-2 in the nanomolar range and showed double-digit micromolar cytotoxicity against four different cancer cell lines.

Omega-3PUFA Attenuates MNU-Induced Colorectal Cancer in Rats by Blocking PI3K/AKT/Bcl-2 Signaling

Background

Omega 3 polyunsaturated fatty acid (Omega-3PUFA) is one of the essential nutrients for human body involved in intracellular metabolic regulation and cell signaling. Previous studies have shown that Omega-3PUFA is involved in the pathogenesis of digestive system tumors, including colorectal cancer (CRC), however, the effects of Omega-3PUFA on CRC has not been fully elucidated. In the current study, we evaluated whether Omega-3PUFA can alleviate N-methyl-N-nitrosourea(MNU) induced CRC in a rat model and illustrated the potential mechanism.

Methods

The effects of Omga-3PUFA on MNU-induced colorectal cancer in rats were analyzed by in vivo experiments. The viability, apoptosis, colony formation and invasion of CRC cells treated with Omga-3PUFA were detected by CCK8, flow cytometry, clone formation assay and transwell invasion assay. The expression of apoptosis-related proteins in CRC cells treated with Omga-3PUFA was detected by Western blotting. Finally, after adding PI3K activator, the viability, apoptosis and protein expression of CRC cells treated with Omga-3PUFA were detected by CCK8, flow cytometry and Western blotting.

Results

Our results showed that Omega-3PUFA attenuated MNU-induced CRC in rats and inhibited AKT/Bcl-2 signaling in rats. In addition, Omega-3PUFA inhibited CRC cell proliferation and induces CRC cell apoptosis. Moreover, Omega-3PUFA inhibited CRC cell colony formation and invasion, and inhibited PI3K/AKT/Bcl-2 signaling in CRC cells. Furthermore, The effects of Omega-3PUFA on cell proliferation and apoptosis were inhibited by blocking PI3K/AKT signaling.

Conclusion

Omega-3PUFA can attenuate MNU-induced colorectal cancer in rats by blocking PI3K/AKT/Bcl-2 signaling, which suggests that Omega-3PUFA may be a potent agent for CRC treatment.

Enhanced signaling via ERBB3/PI3K plays a compensatory survival role in pancreatic tumor cells exposed to [neratinib + valproate]

The ERBB1/2/4 inhibitor neratinib causes plasma membrane-associated K-RAS to mislocalize into intracellular vesicles; this effect is enhanced by HDAC inhibitors and the combination of [neratinib + sodium valproate] is now a phase I trial (NCT03919292). The present studies were performed to understand resistance mechanisms that evolve following [neratinib + valproate] exposure. Exposure of pancreatic tumor cells to [neratinib + sodium valproate] initially reduced the expression and phosphorylation of ERBB family receptors, c-MET and c-KIT. Following a 24 h drug exposure and a further 24 h culture in drug free conditions, the effects on c-MET, c-KIT and most ERBB family receptors had returned to near baseline levels. However, the expression and phosphorylation of ERBB3 were increased which was associated with elevated AKT T308 phosphorylation. Knock down of ERBB3 significantly enhanced [neratinib + valproate] lethality, which was associated with greater inactivation of AKT, mTOR, p70 S6K and ERK1/2. The PI3Kα/δ inhibitor copanlisib also significantly enhanced killing after [neratinib + valproate] exposure. Copanlisib enhanced [neratinib + valproate] lethality via autophagosome formation and autophagic flux. Our data argue for further in vivo exploration as to whether copanlisib can be safely combined with [neratinib + valproate].