Hepatocellular carcinoma is one of the leading causes of death in cancer and yet no drug has proven to be a successful candidate for its treatment in advanced stages. Ursolic acid stearoyl glucoside (UASG) is a newly discovered triterpene in Lantana camara and there lies a possibility that it possess anti-hepatocellular carcinoma property. In the present study, we induced hepatocellular carcinoma in Wistar rats by diethylnitrosamine (DENA) and treated it with ursolic acid stearoyl glucoside. The ability to treat hepatocellular carcinoma was measured by comparing biochemical serum markers such as serum alanine aminotransferase, serum aspartate aminotransferase, serum alkaline phosphatase, and the specific marker for hepatocellular carcinoma, alpha fetoprotein. The histological studies of the livers were also performed. The results have shown significant elevated levels of these parameters as compared to normal control and the drug receiving groups have shown significant reduction in these marker levels. Histopathological studies also indicated the reduced liver damage in drug-treated groups. It was noted that a significant and dose-dependent reversal of DENA-diminished activity of antioxidant enzymes like superoxide dismutase, catalase, glutathione peroxidase, glutathione transferase, and the reduced DENA-elevated level of lipid peroxidation (LPO) with a marked change. UASG significantly suppressed free radical formation by scavenging the hydroxyl radicals. It also modulates the levels of LPO and markedly increases the endogenous antioxidant enzymes level in DENA-induced hepatocellular carcinogenesis.

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Background: Proteasomes are conserved proteases that are crucial for proteostasis in eukaryotes. They are promising drug targets for protozoan parasites. Despite this, the 26S proteasomes of the protozoan parasite Entamoeba histolytica has not received much attention. This study reports a comprehensive bioinformatics analysis of the 26S proteasome subunits of Entamoeba histolytica and related Entamoeba species. Results: While showing overall conservation, critical substitutions in structurally and functionally important residues were observed in both regulatory (RP) and core particle (CP) subunits. Comparative sequence analysis suggests that the substrate translocation channel of E. histolytica has a changed polarity, and is possibly wider, compared to host proteasomes. The proteolytic subunits show differences in the substrate binding sites, especially the S1 and S3 binding pockets of the b1 subunit, that show T22M, A27V, T31K R45T substitutions suggesting differences in size and charge of the pockets. Similarly, b2 has T52L and E22V and b5 has A22R, A27S, S115D and E116G substitutions. These changes in the substrate binding pockets suggest differences in substrate preference and susceptibility to inhibitors compared to host proteasomes. Computational models of β4 and β5 subunits, and a docked β4-β5 model were developed. A binding pocket between β4-β5, similar to that of Leishmania tarentolae was observed. Selective inhibitors for visceral leishmaniasis, LXE408 and compound 8, docked well to this pocket. Conclusions: This sequence based analysis predicts potential points of differences from the host proteasomes that can be experimentally tested, and can be utilized to develop selective inhibitors against E. histolytica.

Proteasomes are conserved proteases that are crucial for proteostasis in eukaryotes. They are promising drug targets for protozoan parasites. We present a comprehensive bioinformatics analysis of the 26S proteasome subunits of Entamoeba histolytica. While showing overall conservation, critical substitutions in structurally and functionally important residues were observed in both regulatory (RP) and core particle (CP) subunits. Comparative sequence analysis suggests that the substrate translocation channel of E. histolytica has a changed polarity, and is possibly wider, compared to host proteasomes. The proteolytic subunits show differences in the substrate binding sites, especially the S1 and S3 binding pockets of the β1 subunit, that shows T22M, A27V, T31K R45T substitutions suggesting differences in size and charge of the pockets. Similarly, β2 has T52L and E22V and β5 has A22R, A27S, S115D and E116G substitutions. These changes in the substrate binding pockets suggest differences in substrate preference and susceptibility to inhibitors compared to host proteasomes. Computational models of β4 and β5 subunits, and a docked β4-β5 model were developed. A binding pocket between β4-β5, similar to that of Leishmania tarentolae was observed. Selective inhibitors for visceral leishmaniasis, LXE408 and compound 8, docked well to this pocket. This sequence based analysis predicts potential points of differences from the host proteasomes that can be experimentally tested, and can be utilized to develop selective inhibitors against E. histolytica.

Entamoeba histolytica causes amoebiasis which is a major health concern in developing countries. E. histolytica pathogenicity has been implicated to a large repertoire of small GTPases which switch between the inactive GDP bound state and the active GTP bound state with the help of guanine nucleotide exchange factors (GEFs) and GTPase activating protein (GAPs). Rho family of small GTPases are well known to modulate the actin cytoskeletal dynamics which plays a major role in E. histolytica pathogenicity. Here, we report an atypical amoebic RhoGEF, and its preferred substrate EhRho6, which, upon overexpression abrogated the pathogenic behavior of the amoeba such as adhesion to host cell, monolayer destruction, erythrophagocytosis, and formation of actin dots. A causative immunoblot analysis revealed actin degradation in the EhRho6 overexpressing trophozoites that could be inhibited by blocking the amoebic proteasomal pathway. A careful analysis of the results from a previously published transcriptomics study, in conjunction with our observations, led to the identification of a clade of Rho GTPases in this pathogenic amoeba which we hypothesize to have implications during the amoebic encystation.