CD22 is an inhibitory B cell coreceptor that regulates B cell development and activation by downregulating BCR signaling through activation of SH2-containing protein tyrosine phosphatase-1 (SHP-1). CD22 recognizes α2,6 sialic acid as a specific ligand and interacts with α2,6 sialic acid-containing membrane molecules, such as CD45, IgM, and CD22, expressed on the same cell. Functional regulation of CD22 by these endogenous ligands enhances BCR ligation-induced signaling and is essential for normal B cell responses to Ags. In this study, we demonstrate that CD45 plays a crucial role in CD22-mediated inhibition of BCR ligation-induced signaling. However, disruption of ligand binding of CD22 enhances CD22 phosphorylation, a process required for CD22-mediated signal inhibition, upon BCR ligation in CD45^-/- as well as wild-type mouse B cells but not in mouse B cells expressing a loss-of-function mutant of SHP-1. This result indicates that SHP-1 but not CD45 is required for ligand-mediated regulation of CD22. We further demonstrate that CD22 is a substrate of SHP-1, suggesting that SHP-1 recruited to CD22 dephosphorylates nearby CD22 as well as other substrates. CD22 dephosphorylation by SHP-1 appears to be augmented by homotypic CD22 clustering mediated by recognition of CD22 as a ligand of CD22 because CD22 clustering increases the number of nearby CD22. Our results suggest that CD22 but not CD45 is an endogenous ligand of CD22 that enhances BCR ligation-induced signaling through SHP-1-mediated dephosphorylation of CD22 in CD22 clusters.

1. Eicosanoids like leukotrienes and prostaglandins that produced within the arachidonic acid cascade are involved in the pathogenesis of pain, acute and chronic inflammatory diseases. A promising approach for an effective anti-inflammatory therapy is the development of inhibitors targeting more than one enzyme of this cascade. Aiming to develop balanced COX/LOX inhibitors; 4-aminosalicylate based thiazolinones having different substituents at the 5th position of the 4-thiazolinone ring (2-22) were designed, synthesized, characterized and evaluated in vitro and in vivo for their anti-inflammatory activity. Most of the investigated compounds showed high COX-2 inhibitory potencies (IC₅₀ 39-200 nM) with selectivity indexes (30-84). Two compounds, 19 and 21, (IC₅₀ = 41 and 44 nM), are equipotent to celecoxib (IC₅₀ = 49 nM), while compound 22 (IC₅₀ = 39 nM) was the most potent. For 15-LOX, compounds 5, 11, 19, 21 and 22 revealed higher potency (IC₅₀ 1.5-2.2 µM) than zileuton (IC₅₀ 15 µM). Thus, compounds 5, 11, 19, 21 and 22 are potent dual inhibitors of COX-2 and 15-LOX. In vivo anti-inflammatory testing of these compounds revealed that, compounds 5 and 21 had an anti-inflammatory activity similar to indomethacin and celecoxib (% inhibition of oedema = 60 ± 9) and higher than diclofenac potassium (% inhibition = 52 ± 29), while compound 22 (% inhibition = 63 ± 5) was more active than the reference drugs. The results showed that the activity is controlled by the bulkiness and lipophilicity of the substituent at the 5th position. The cytotoxicity results revealed that all compounds are not cytotoxic, additionally, in an experimental model of ulcerogenic effect, the most active compounds 21 and 22 showed better safety profile than indomethacin. Further, at the active sites of the COX-1, COX-2 and 15-LOX co-crystal, 19, 21, and 22 showed high binding forces in free binding energy study, which is consistent with in vitro and in vivo results. In conclusion, these compounds are good candidates for further biological investigation as potential anti-inflammatory drugs with dual balanced inhibition of COX and 15-LOX and good safety profile.

A potential microtubule destabilizing series of new thirty-five Pyrrol-2-one, Pyridazin-3(2H)-one and Pyridazin-3
(2H)-one/oxime derivatives has been synthesized and tested for their antiproliferative activity against a panel of
60 human cancer cell lines. Compounds IVc, IVg and IVf showed a broad spectrum of growth inhibitory activity
against cancer cell lines representing renal, cancer of lung, colon, central nervous system, ovary, and kidney.
Among them, compound IVg was found to have broad spectrum anti-tumor activity against the tested nine tumor
subpanels with selectivity ratios ranging between 0.21 and 3.77 at the GI50 level. In vitro assaying revealed
tubulin polymerization inhibition by all active compounds IVc, IVg and IVf. The results of the docking study
revealed nice fitting of compounds IVc, IVf, and IVg into CA-4 binding site in tubulin. The three compounds
exhibited high binding affinities (ΔGb = - 12.49 to -12.99 kcal/mol) toward tubulin compared to CA-4 (- 8.87
kcal/mol). Investigation of the binding modes of the three compounds IVc, IVf, and IVg revealed that they
interacted mainly hydrophobically with tubulin and similar binding orientations to that of CA-4. These observations
suggest that tubulin is a possible target for these compounds.

A series of novel piperine–resveratrol hybrids 5a–h was designed, synthesized, and structurally elucidated
by IR, and 1H, 13C, and 19F NMR. Antiproliferative activities of 5a–h were evaluated by NCI against sixty
cancer cell lines. Compound 5b, possessing resveratrol pharmacophoric phenolic moieties, showed
a complete cell death against leukemia HL-60 (TB) and Breast cancer MDA-MB-468 with growth
inhibition percentage of
0.49 and
2.83, respectively. In addition, 5b recorded significant activity
against the other cancer cell lines with growth inhibition percentage between 80 to 95. New 5a–h
hybrids were evaluated for their inhibitory activities against Sirt-1 and Sirt-2 as molecular targets for their
antiproliferative action. Results showed that compounds 5a–h were more potent inhibitors of Sirt-2 than
Sirt-1 at 5 mm and 50 mm. Compound 5b showed the strongest inhibition of Sirt-2 (78  3% and 26  3%
inhibition at 50 mM and 5 mM, respectively). Investigation of intermolecular interaction via Hirschfeld
surface analysis indicates that these close contacts are mainly ascribed to the O–H/O hydrogen
bonding. To get insights into the Sirt-2 inhibitory mechanism, a docking study was performed where 5b
was found to fit nicely inside both extended C-pocket and selectivity pocket and could compete with
the substrate acyl-Lys. Another possible binding pattern showed that 5b could act by partial occlusion of
the NAD+ C-pocket. Collectively, these findings would contribute significantly to better understanding
the Sirt-2 inhibitory mechanism in order to develop a new generation of refined and selective Sirt-2
inhibitors.