Browsing by Author "Kituyi, Sarah Naulikha"

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    In vitro anti-cancer efficacy and phyto-chemical screening of solvent extracts of Kigelia africana (Lam.) Benth
    (Cell press, 2021-01-25) Nyaga, Justine M.; Mukavi, Justus Wambua; Mayeku, Philip Wafula; Kituyi, Sarah Naulikha
    Background and objectives: Kigelia africana is a medicinal plant growing naturally in many parts of Africa. In Kenya, a water concoction of the plant is used to treat breast and prostate cancers. Laboratory data on its anti-cancer activity and active principles is limited, hence no scientific rationale for its medicinal use. This study reports on in-vitro toxic activities of dichloromethane and methanol extracts of the plant against human breast cancer cells and phytochemical screening of the two extracts. Methodology: Plant extracts were obtained by sequential solvent extraction of dry plant material (stem bark) using analytical grade dichloromethane: methanol (1:1) and methanol (Sigma Aldrich). In-vitro anti-cancer activities of the extracts were determined using the suphorhodamine (SRB) assay against a human breast cancer cell line (HCC 1937). Preliminary Thin layer chromatography of plant extracts was done using POLYGRAM® SIL G/UV254 plates (Merck) to establish presence of different classes of secondary metabolites. Results: In-vitro cytotoxic activities of the two extracts were significantly different (P ¼ 0.05). The methanol extract exhibited higher activity (IC50 ¼ 26.02 μg/ml) compared to that of dichloromethane: methanol (1:1) (IC50 ¼ 55.01 μg/ml). Phyto-chemical screening of the two extracts revealed the presence of terpenoids, phenols, steroids and flavonoids. Conclusion: The high in-vitro anti-cancer activities of solvent extracts of Kigelia africana justify its use in traditional medicine to manage breast cancer. Phytochemical analysis of the extracts reveal similar profiles hence the differences in their anti-cancer activities can be attributed to quantitative variations of various classes of secondary metabolites.
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    STIP1/HOP Regulates the Actin Cytoskeleton through Interactions with Actin and Changes in Actin-Binding Proteins Cofilin and Profilin
    (MDPI, 2020-04) Beckley, Samantha Joy; Hunter, Morgan Campbell; Kituyi, Sarah Naulikha; Wingate, Ianthe; Chakraborty, Abantika; Schwarz, Kelly; Makhubu, Matodzi Portia; Rousseau, Robert Pierre; Ruck, Duncan Kyle; de la Mare, Jo-Anne; Blatch, Gregory Lloyd; Edkins, Adrienne Lesley
    Cell migration plays a vital role in both health and disease. It is driven by reorganization of the actin cytoskeleton, which is regulated by actin-binding proteins cofilin and profilin. Stress-inducible phosphoprotein 1 (STIP1) is a well-described co-chaperone of the Hsp90 chaperone system, and our findings identify a potential regulatory role of STIP1 in actin dynamics. We show that STIP1 can be isolated in complex with actin and Hsp90 from HEK293T cells and directly interacts with actin in vitro via the C-terminal TPR2AB-DP2 domain of STIP1, potentially due to a region spanning two putative actin-binding motifs. We found that STIP1 could stimulate the in vitro ATPase activity of actin, suggesting a potential role in the modulation of F-actin formation. Interestingly, while STIP1 depletion in HEK293T cells had no major effect on total actin levels, it led to increased nuclear accumulation of actin, disorganization of F-actin structures, and an increase and decrease in cofilin and profilin levels, respectively. This study suggests that STIP1 regulates the cytoskeleton by interacting with actin, or via regulating the ratio of proteins known to affect actin dynamics.