The Bile Salt Export Pump: Molecular Structure, Study Models and Small-Molecule Drugs for the Treatment of Inherited BSEP Deficiencies.

The bile salt export pump (BSEP/ABCB11) is responsible for the transport of bile salts from hepatocytes into bile canaliculi. Malfunction of this transporter results in progressive familial intrahepatic cholestasis type 2 (PFIC2), benign recurrent intrahepatic cholestasis type 2 (BRIC2) and intrahepatic cholestasis of pregnancy (ICP). Over the past few years, several small molecular weight compounds have been identified, which hold the potential to treat these genetic diseases (chaperones and potentiators). As the treatment response is mutation-specific, genetic analysis of the patients and their families is required. Furthermore, some of the mutations are refractory to therapy, with the only remaining treatment option being liver transplantation. In this review, we will focus on the molecular structure of ABCB11, reported mutations involved in cholestasis and current treatment options for inherited BSEP deficiencies.

Silybum marianum (milk thistle) improves vancomycin induced nephrotoxicity by downregulating apoptosis.

Increased use of vancomycin for treating infections, and the associated risk of causing nephrotoxicity lead to the present study. The antioxidant and anti-apoptotic potential of Silybum marianum is used along with vancomycin to reduce adverse effects on the kidney. Vero cells (monkey kidney cells) and mice were used to test S. marianum extract on vancomycin induced nephrotoxicity. Vero cells were treated with different concentrations of vancomycin and S. marianum for 24 h for determination of cytotoxic potential and mRNA levels of apoptotic genes p53 , p21, and cyt-c were measured. For in-vivo studies mice were divided into five groups; G1 control (untreated), G2 vehicle (olive oil), G3 vancomycin treated (300 mg/kg body weight), G4 (S. marianum; 400 mg/kg bodyweight and vancomycin 300 mg/kg bodyweight simultaneously) and G5 (S. marianum 400 mg/kg bodyweight and vancomycin 300 mg/kg bodyweight treatment started after day 4 of S. marianum treatment). After 10 days histopathological analysis of mice kidneys was performed, serum urea and creatinine were analysed and mRNA expression of p53 , p21, and cyt-c was evaluated. Expression of p53, p21, and cyt-c in Vero cells was elevated in response to vancomycin treatment, whereas after S. marianum administration expression of these genes reduced. Vancomycin showed apoptosis in cells at the concentration of 6 mg/ml (LC50). Urea and creatinine levels in mice were increased in response to vancomycin administration and kidney histology showed an abnormality in functional units. The apoptotic cells were very visible in kidney structure in vancomycin treated group. These symptoms were however relieved in groups where treatment of S. marianum extract was given. mRNA expression of p53 , p21, and cyt-c also reduced in S. marianum treated groups of mice. S. marianum extract has protective effects against renal damage from vancomycin induced oxidative stress and relieves symptoms may be by downregulating apoptotic genes.

Disseminated Hydatid Disease in a Child Involving Multiple Organ Systems: A Case Report.

Hydatid disease is a parasitic infestation by Echinococcus granulosus, which involves the liver and lungs primarily. The authors report a case of disseminated hydatid disease involving multiple organs simultaneously in a 7-year-old child from Kabul, Afghanistan. The patient under examination had been having a complaint of cough and low-grade fever for the last one year. Computed tomography (CT) and ultrasonography (USG) demonstrated cystic lesions in his liver, lungs, spleen, and suprarenal region. The literature review showed that it was very rare for hydatid disease to involve multiple organs simultaneously, even in endemic areas, and the management of disseminated disease was very challenging, especially in the pediatric population.

Recent updates on true potential of an anesthetic agent as a regulator of cell signaling pathways and non-coding RNAs in different cancers: Focusing on the brighter side of propofol.

There has always been a quest to search for synthetic and natural compounds having premium pharmacological properties and minimum off-target and/or side effects. Therefore, in accordance with this approach, scientists have given special attention to the molecules having remarkable ability to target oncogenic protein network, restore drug sensitivity and induce apoptosis in cancer cells. The mechanisms through which general anesthetics modulated wide-ranging deregulated cell signaling pathways and non-coding RNAs remained unclear. However, rapidly accumulating experimentally verified evidence has started to resolve this long-standing mystery and a knowledge about these important molecular targets has surfaced and how these drugs act at the molecular level is becoming more understandable. In this review we have given special attention to available evidence related to ability of propofol to modulate Wnt/ß-catenin, JAK/STAT and mTOR-driven pathway. Excitingly, great strides have been made in sharpening our concepts related to potential of propofol to modulate non-coding RNAs in different cancers. Collectively, these latest findings offer interesting, unexplored opportunities to target deregulated signaling pathways to induce apoptosis in drug-resistant cancers.

Focusing on the brighter side of Sevoflurane: Realizing true potential of an anesthetic agent as a regulator of cell signaling pathways and microRNAs in different cancers.

Reconceptualization of different anesthetics as anticancer agents has opened new horizons for a better and sharper analysis of true potential of Sevoflurane as a promising and frontline candidate in the pipeline of anticancer agents. Sevoflurane mediated regulation of cell signaling pathways and non-coding RNAs has leveraged our understanding to another level. There have been remarkable advancements in unraveling mechanistic insights related to the ability of sevoflurane to modulate microRNAs in different cancers. Astonishingly, sevoflurane mediated regulation of miRNAs and long non-coding RNAs have been more comprehensively addressed in ischemia-reperfusion injuries. However, researchers yet have to gather missing pieces of premium research-work to uncover mechanistic regulation of long non-coding RNAs by sevoflurane in various cancers. Sevoflurane modulated control of miRNAs have been reported in glioma, colorectal cancer, breast cancer and hepatocellular carcinoma. In this review we have attempted to summarize most recent cutting edge and high-impact experimental researches which have elucidated myriad of underlying mechanisms modulated by sevoflurane to inhibit cancer development and progression. Despite some of the amazing pharmacological properties of sevoflurane, it has been shown to possess darker side because of its involvement in positive regulation of metastasis.  In accordance with this notion we have also summarized how sevoflurane enhanced migratory potential of different cancer cells in a separate section. Therefore, these aspects have to be tested in better designed experimental models to identify most relevant types of cancers which can be therapeutically targeted by sevoflurane.

Interplay of long non-coding RNAs and TGF/SMAD signaling in different cancers.

Based on the exciting insights gleaned from decades of ground-breaking research, it has become evident that deregulated signaling pathways play instrumental role in cancer development and progression. Interestingly discovery of non-coding RNAs has revolutionized our understanding related to transcription, post-transcription and translation. Modern era has witnessed landmark discoveries in the field of molecular cancer and non-coding RNA biology has undergone tremendous broadening. There has been an exponential growth in the list of publications related to non-coding RNAs and overwhelmingly increasing classes of non-coding RNAs are adding new layers of complexity to already complicated nature of cancer. Regulation of TGF/SMAD signaling by miRNAs and LncRNAs has opened new horizons for therapeutic targeting of TGF/SMAD pathway. In this review we have set spotlight on central role of LncRNAs in modulation of TGF/SMAD pathway. Major proportion of the available evidence is underlining positive role of LncRNAs in contextual regulation of TGF/SMAD pathway. LncRNAs are vital to these regulatory networks because they provide a background support to make the TGF/SMAD mediated intracellular signaling more smooth or make transduction cascade more flexible in response to cues from extracellular environment. Therefore, in accordance with this notion, MALAT1, OIP5-AS1, MIR100HG, HOTAIR, ANRIL, PVT1, AFAP1-AS1, SPRY4-IT, ZEB2NAT, TUG1 and Lnc-SNHG1 have been reported to positively regulate TGF/SMAD signaling. In this review, we have focused on the regulation of TGF/SMAD signaling by LncRNAs and how these non-coding RNAs can be therapeutically exploited. Short-interfering RNA (siRNA) and natural products are currently being tested for efficacy against different LncRNAs. Nanotechnological strategies to efficiently deliver LncRNA-targeting siRNAs are also currently being investigated in different cancers.

Molecular Mechanism of Taurocholate Transport by the Bile Salt Export Pump, an ABC Transporter Associated with Intrahepatic Cholestasis.

The bile salt export pump (BSEP/ABCB11) transports bile salts from hepatocytes into bile canaliculi. Its malfunction is associated with severe liver disease. One reason for functional impairment of BSEP is systemic administration of drugs, which as a side effect inhibit the transporter. Therefore, drug candidates are routinely screened for potential interaction with this transporter. Hence, understanding the functional biology of BSEP is of key importance. In this study, we engineered the transporter to dissect interdomain communication paths. We introduced mutations in noncanonical and in conserved residues of either of the two nucleotide binding domains and determined the effect on BSEP basal and substrate-stimulated ATPase activity as well as on taurocholate transport. Replacement of the noncanonical methionine residue M584 (Walker B sequence of nucleotide binding site 1) by glutamate imparted hydrolysis competency to this site. Importantly, this mutation was able to sustain 15% of wild-type transport activity, when the catalytic glutamate of the canonical nucleotide binding site 2 was mutated to glutamine. Kinetic modeling of experimental results for the ensuing M584E/E1244Q mutant suggests that a transfer of hydrolytic capacity from the canonical to the noncanonical nucleotide binding site results in loss of active and adoption of facilitative characteristics. This facilitative transport is ATP-gated. To the best of our knowledge, this result is unprecedented in ATP-binding cassette proteins with one noncanonical nucleotide binding site. Our study promotes an understanding of the domain interplay in BSEP as a basis for exploration of drug interactions with this transporter.

Folding correction of ABC-transporter ABCB1 by pharmacological chaperones: a mechanistic concept.

Point mutations of ATP-binding cassette (ABC) proteins are a common cause of human diseases. Available crystal structures indicate a similarity in the architecture of several members of this protein family. Their molecular architecture makes these proteins vulnerable to mutation, when critical structural elements are affected. The latter preferentially involve the two transmembrane domain (TMD)/nucleotide-binding domain (NBD) interfaces (transmission interfaces), formation of which requires engagement of coupling helices of intracellular loops with NBDs. Both, formation of the active sites and engagement of the coupling helices, are contingent on correct positioning of ICLs 2 and 4 and thus an important prerequisite for proper folding. Here, we show that active site compounds are capable of rescuing P-glycoprotein (P-gp) mutants ∆Y490 and ∆Y1133 in a concentration-dependent manner. These trafficking deficient mutations are located at the transmission interface in pseudosymmetric position to each other. In addition, the ability of propafenone analogs to correct folding correlates with their ability to inhibit transport of model substrates. This finding indicates that folding correction and transport inhibition by propafenone analogs are brought about by binding to the active sites. Furthermore, this study demonstrates an asymmetry in folding correction with cis-flupentixol, which reflects the asymmetric binding properties of this modulator to P-gp. Our results suggest a mechanistic model for corrector action in a model ABC transporter based on insights into the molecular architecture of these transporters.