1.Evaluation of berries of Phytolacca dodecandra for growth inhibition of Histoplasma capsulatum var. farciminosum and treatment of cases of epizootic lymphangitis in Ethiopia
Negesse MEKONNEN ; Eyasu MAKONNEN ; Nigatu AKLILU ; Gobena AMENI
Asian Pacific Journal of Tropical Biomedicine 2012;(7):505-510
Objective:To evaluate the berries of Phytolacca dodecandra (P. dodecandra) for its effect on Histoplasma capsulatum var. farciminosum (HCF) and for the treatment of cases of epizootic lymphangitis (EL). Methods:Samples were collected from un-ruptured nodules of cases of EL at Debre Zeit and Akaki (central Ethiopia). Mycological culture and isolation of HCF were performed at the Aklilu Lemma Institute of Pathobiology. Phytochemical screening was done for n-butanol extract of P. dodecandra to detect alkaloids, saponins, phenolic compounds and flavonoids. The minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations (MFCs) of aqueous and n-butanol extracts of P. dodecandra against HCF were determined by agar dilution assay. For the in vivo trial, 5%simple ointment was prepared from n-butanol extract and applied topically to 24 (twelve early and twelve moderate) cases of EL. Results:Phytochemical screening showed that n-butanol extract of P. dodecandra was positive for alkaloids, saponins and phenolic compounds but negative for flavonoids. The MICs of n-butanol and aqueous extracts of P. dodecandra were (0.039%-0.078%) and (0.625%-1.250%), respectively. The MFCs of n-butanol and aqueous extracts of P. dodecandra were (0.078%-0.156%) and (1.250%-2.500%), respectively. The MIC and MFC of ketoconazole (positive control) was (1.200×10-5%-2.500×10-5%) and (5.000×10-5%-1.000×10-4%), respectively while growth was observed on free medium (negative control). From the total of 24 treated cases of EL, 14 (58.3%) responded to treatment;however, 10 (41.7%) did not respond to treatment. There was no significant difference in the degree of response to treatment between early and moderate cases (χ2=0.686;P=0.408). Conclusions:It can be concluded that n-butanol extract of P. dodecandra demonstrates antifungal effects while the aqueous extract shows no antifungal activity.
2.Design, Screening and Development of Asymmetric siRNAs Targeting the MYC Oncogene in Triple-Negative Breast Cancer
Negesse MEKONNEN ; Myeung-Ryun SEO ; Hobin YANG ; Chaithanya CHELAKKOT ; Jun Young CHOI ; Sungyoul HONG ; Kyoung SONG ; Young Kee SHIN
Biomolecules & Therapeutics 2025;33(1):155-169
Triple-negative breast cancer (TNBC) is a subtype of breast cancer that lacks hormone receptor and Her2 (ERBB2) expression, leaving chemotherapy as the only treatment option. The urgent need for targeted therapy for TNBC patients has led to the investigation of small interfering RNAs (siRNAs), which can target genes in a sequence-specific manner, unlike other drugs. However, the clinical translation of siRNAs has been hindered by the lack of an effective delivery system, except in the case of liver diseases. The MYC oncogene is commonly overexpressed in TNBC compared to other breast cancer subtypes. In this study, we used siRNA to target MYC in MDA-MB-231, MDA-MB-157, MDA-MB-436 and Hs-578T cells. We designed various symmetric and asymmetric (asiRNAs), screened them for in vitro efficacy, modified them for enhanced nuclease resistance and reduced off-target effects, and conjugated them with cholesterol (ChoL) and docosanoic acid (DCA) as a delivery system. DCA was conjugated to the 3’ end of asiRNA by a cleavable phosphodiester linker for in vivo delivery. Our findings demonstrated that asiRNA-VP and Mod_asiRNA10-6 efficiently downregulated MYC and its downstream targets, including RRM2, RAD51 and PARP1. Moreover, in a tumor xenograft model, asiRNA-VP-DCA effectively knocked down MYC mRNA and protein expression. Remarkably, durable knockdown persisted for at least 46 days postdosing in mouse tumor xenografts, with no visible signs of toxicity, underscoring the safety of DCA-conjugated asiRNAs. In conclusion, this study developed novel asiRNAs, design platforms, validated modification patterns, and in vivo, delivery systems specifically targeting MYC in TNBC.
3.Design, Screening and Development of Asymmetric siRNAs Targeting the MYC Oncogene in Triple-Negative Breast Cancer
Negesse MEKONNEN ; Myeung-Ryun SEO ; Hobin YANG ; Chaithanya CHELAKKOT ; Jun Young CHOI ; Sungyoul HONG ; Kyoung SONG ; Young Kee SHIN
Biomolecules & Therapeutics 2025;33(1):155-169
Triple-negative breast cancer (TNBC) is a subtype of breast cancer that lacks hormone receptor and Her2 (ERBB2) expression, leaving chemotherapy as the only treatment option. The urgent need for targeted therapy for TNBC patients has led to the investigation of small interfering RNAs (siRNAs), which can target genes in a sequence-specific manner, unlike other drugs. However, the clinical translation of siRNAs has been hindered by the lack of an effective delivery system, except in the case of liver diseases. The MYC oncogene is commonly overexpressed in TNBC compared to other breast cancer subtypes. In this study, we used siRNA to target MYC in MDA-MB-231, MDA-MB-157, MDA-MB-436 and Hs-578T cells. We designed various symmetric and asymmetric (asiRNAs), screened them for in vitro efficacy, modified them for enhanced nuclease resistance and reduced off-target effects, and conjugated them with cholesterol (ChoL) and docosanoic acid (DCA) as a delivery system. DCA was conjugated to the 3’ end of asiRNA by a cleavable phosphodiester linker for in vivo delivery. Our findings demonstrated that asiRNA-VP and Mod_asiRNA10-6 efficiently downregulated MYC and its downstream targets, including RRM2, RAD51 and PARP1. Moreover, in a tumor xenograft model, asiRNA-VP-DCA effectively knocked down MYC mRNA and protein expression. Remarkably, durable knockdown persisted for at least 46 days postdosing in mouse tumor xenografts, with no visible signs of toxicity, underscoring the safety of DCA-conjugated asiRNAs. In conclusion, this study developed novel asiRNAs, design platforms, validated modification patterns, and in vivo, delivery systems specifically targeting MYC in TNBC.
4.Design, Screening and Development of Asymmetric siRNAs Targeting the MYC Oncogene in Triple-Negative Breast Cancer
Negesse MEKONNEN ; Myeung-Ryun SEO ; Hobin YANG ; Chaithanya CHELAKKOT ; Jun Young CHOI ; Sungyoul HONG ; Kyoung SONG ; Young Kee SHIN
Biomolecules & Therapeutics 2025;33(1):155-169
Triple-negative breast cancer (TNBC) is a subtype of breast cancer that lacks hormone receptor and Her2 (ERBB2) expression, leaving chemotherapy as the only treatment option. The urgent need for targeted therapy for TNBC patients has led to the investigation of small interfering RNAs (siRNAs), which can target genes in a sequence-specific manner, unlike other drugs. However, the clinical translation of siRNAs has been hindered by the lack of an effective delivery system, except in the case of liver diseases. The MYC oncogene is commonly overexpressed in TNBC compared to other breast cancer subtypes. In this study, we used siRNA to target MYC in MDA-MB-231, MDA-MB-157, MDA-MB-436 and Hs-578T cells. We designed various symmetric and asymmetric (asiRNAs), screened them for in vitro efficacy, modified them for enhanced nuclease resistance and reduced off-target effects, and conjugated them with cholesterol (ChoL) and docosanoic acid (DCA) as a delivery system. DCA was conjugated to the 3’ end of asiRNA by a cleavable phosphodiester linker for in vivo delivery. Our findings demonstrated that asiRNA-VP and Mod_asiRNA10-6 efficiently downregulated MYC and its downstream targets, including RRM2, RAD51 and PARP1. Moreover, in a tumor xenograft model, asiRNA-VP-DCA effectively knocked down MYC mRNA and protein expression. Remarkably, durable knockdown persisted for at least 46 days postdosing in mouse tumor xenografts, with no visible signs of toxicity, underscoring the safety of DCA-conjugated asiRNAs. In conclusion, this study developed novel asiRNAs, design platforms, validated modification patterns, and in vivo, delivery systems specifically targeting MYC in TNBC.