Kobe0065

Kobe0065 is a novel and effective inhibitor of Ras-Raf interaction, competitively inhibiting the binding of H-Ras·GTP to c-Raf-1 RBD with a Ki value of 46±13 μM.

Signaling Pathways >> GPCR/G Protein >> Ras

Research Areas >> Cancer

Kobe0065-family compounds bind to Ras•GTP and exhibit antiproliferative activity toward cancer cells carrying the activated ras oncogenes. The compounds efficiently inhibit the interaction of Ras•GTP with their multiple effectors including Raf, PI3K, and RalGDS and a regulator/effector Sos and show rather broad binding specificity toward various Ras family small GTPases, which may account for their higher potency at the cellular level compared with that of the in vitro binding inhibition[1]. The phosphorylation of downstream kinases MEK and ERK is effectively attenuated by 20 μM Kobe0065 and Kobe2602 in NIH3T3 cells transiently expressing H-RasG12V[2].

Kobe0065 and Kobe2602 exhibit antitumor activity on a xenograft of human colon carcinoma SW480 cells carrying the K-ras(G12V) gene by oral administration[1].

Cells (2×103) are seeded in a 96-well plate and cultured in DMEM containing 2% (vol/vol) FBS in the presence of one of the compounds. Viable cell numbers are measured by formazan formation using a Cell Counting Kit 8. Apoptotic cells are detected by a standard TUNEL assay using an In Situ Cell Detection kit.

Cells (5×106) are implanted into the right flanks of female athymic nude mice (6-8 wk old). After tumor sizes reached appr 50 mm3 on average, compounds suspended in Cremophor:ethanol:water (1:1:6) are administered orally for five consecutive days per week for 17 d. Tumor volumes (V) are calculated. Dissected tumors after 17-d administration of the 80 mg/kg compounds are fixed in 4% (wt/vol) paraformaldehyde and embedded in paraffin. Their sections are subjected to immunohistochemistry with an anti-ERK1/2 antibody or an anti-CD31 antibody using a HISTMOUSE-PLUS kit. Apoptotic cells are detected by a TUNEL assay. Statistical significance for groups of three or more is determined by one-way ANOVA with Tukey’s test for post hoc analysis.

[1]. Shima, Fumi, et al. In silico discovery of small-molecule Ras inhibitors that display antitumor activity by blocking the Ras-effector interaction. Proceedings of the National Academy of Sciences of the United States of America (2013), 110(20), 8182-8187,

[2]. Shima F, et al. Discovery of small-molecule Ras inhibitors that display antitumor activity by interfering with Ras·GTP-effector interaction. Enzymes. 2013;34 Pt. B:1-23.

ARS-853 | ARS-1620 | NSC 23766 | ML 141 | Salirasib | Pan-RAS-IN-1 | Rhosin hydrochloride | CASIN | EHT 1864 | EHop-016 | 1A-116 | CCG 1423 | K-Ras(G12C) inhibitor 12 | ZCL 278 | Y16