Розмарин и рак Rosmarinus officinalis & cancer Научные исследования

Discussion

Our NMR studies identified β-catenin as a direct molecular target of CA. Three lines of evidence argue that the observed in vitro effects of CA on R4 could explain its in vivo effects on β-catenin. First, the CA-induced reduction of the cellular β-catenin levels is relatively rapid and dose dependent, consistent with a direct response. Second, the IC₅₀s of the cellular responses of CA overlap its K_i for interfering with HD2-ARD binding, its K_d for binding to R4, and they are within the range of CA concentrations that promote in vitro aggregation of R4. Third, and most important, deletion of H1 eliminates the CA response of R4 in vitro, and that of β-catenin in vivo. This excellent correlation between in vitro and in vivo effects of CA is consistent with the latter reflecting the former, which we shall take to be the case below—bearing in mind that CA could have additional cellular targets that might affect β-catenin stability and outputs.

Our biophysical data suggest that H1 contains, or contributes to, the CA-binding site of R4, and that CA acts through H1 to exacerbate an intrinsic tendency of the ARD N-terminus to aggregate. Given that H1 is intrinsically unstructured19, and our evidence from AUC for a CA-induced R4 shape change, it is conceivable that CA, on binding to the ARD N-terminus, induces a conformational change of H1, which favours aggregation. Indeed, CA may fix H1 in a conformation that is incompatible with its folding into the helical structure necessary for accommodating HD2 (ref. 18; Supplementary Fig. S3), which would explain why CA interferes with HD2-ARD binding. Recall also that CA does not interfere with ARD binding to nTCF (predominantly involving residues downstream of R4 (ref. 34)), further supporting the notion that the CA-induced perturbations are limited to the ARD N-terminus.

In the light of our in vitro observations, we propose that the metastable H1 also predisposes β-catenin to low-grade aggregation in vivo, and that this is exacerbated by CA, which could earmark β-catenin for proteasomal degradation27,35 (Fig. 8). This model could explain why the phosphorylated pool of β-catenin (which in epithelial cells includes junctional β-catenin)36,37 is refractory to CA: this β-catenin pool is complexed with E-cadherin, a high-affinity ligand (with a K_d of ~100 times below the K_i for CA inhibition)38 that confers a helical structure on H1, and protects it from CA inhibition. Note also that β-catenin associates with E-cadherin co-translationally39,40, which would safeguard it against H1-mediated CA effects from its de novo synthesis.

According to our model, H1 constitutes an Achilles' Heel of β-catenin, which, in the absence of ligands that stabilize its structure in a helical conformation18,22,23, earmarks it for proteasomal turnover in cells by promoting localized structural perturbations that favour low-grade aggregation. Notably, an unstructured H1 is also found in β-catenin of other species (Supplementary Table S5), so this Achilles' Heel appears to be conserved. Perhaps, this feature serves as a last-resort tagging mechanism to prevent fortuitous activation of β-catenin, should it fail to bind to its negative regulators. Indeed, H1-dependent proteasomal degradation of β-catenin could be particularly important when its negative regulators are rate limiting, or absent—for example, in colorectal cancer cells with dysfunctional APC, and low E-cadherin levels37. This may render oncogenic β-catenin particularly vulnerable and prone to degradation, a property shared by other oncogenes whose stability is reliant on chaperones such as HSP90 (refs 41,42).

BCL9 family proteins shuttle in and out of the nucleus43, and could thus convey β-catenin from the cytoplasm to chromatin-bound Pygo at TCF-target genes44. Interestingly, excess BCL9 protects unphosphorylated β-catenin against CA-induced degradation, possibly by promoting a helical structure of H1. BCL9 may thus have a chaperone-like ('shepherding') role in protecting oncogenic β-catenin against H1-dependent degradation. We note that BCL9 is a lower-affinity ligand of β-catenin compared with E-cadherin, and may thus need to be present at high levels to afford protection. BCL9 proteins are overexpressed in colorectal cancer cells and carcinomas12,13,14,15 and may thus be effective in safeguarding oncogenic β-catenin against H1-dependent degradation.

β-Catenin is an unattractive drug target, because of its extensive interaction surfaces with TCF and negative regulators4. Our discoveries of an Achilles' Heel at its N-terminus, and of a H1-dependent compound destabilizing oncogenic β-catenin, open up avenues for new screen designs, such as inhibiting R4's interaction with other 'shepherding' ligands of β-catenin—similar to a promising strategy aimed at inhibiting oncogene interactions with their stabilizing HSP90 chaperone42. Indeed, as exemplified by a recent study with c-Myc45, the targeting of intrinsically disordered stretches of proteins such as H1 is an emerging strategy in drug discovery46.

Antiproliferation эффект розмарина (Rosmarinus officinalis) на овариальный рак клеток in vitro.

Розмарин (Rosmarinus officinalis L.) - это популярная кулинария/лечебные травы. Недавние исследования показали, что он имеет Фармакологическое деятельности для рака химиопрофилактики и терапии. В этом исследовании оценивали antiproliferation деятельности экстракт розмарина (RE) против человеческих яичников, раковых клеток, и является ли экстракт и три его основные активные ингредиенты carnosol (CS), carnosic кислоты (CA) и розмариновой кислоты (RA) может повысить antiproliferation деятельности цисплатин (CDDP). Наше исследование показало, что ре имеет значительный antiproliferation деятельности на овариальный рак A2780 и CDDP упорная дочь клеточной линии A2780CP70, с IC(50) (50% ингибирующая концентрация) оценивается в 1/1000 и 1/400 разведениях соответственно. RE повысила antiproliferation эффект с CDDP на обоих A2780 и A2780CP70 клеток. Клеток A2780 были последовательно более чувствительны к CS, CA, RA, чем A2780CP70 клеток между 2.5 и 20μg/мл. CS и ра также свидетельствуют о синергизме antiproliferation эффект с CDDP на A2780 клеток в какой-то концентрации. RE обработанной методом ультрафильтрации, диализа и удаления фенолов потерял antiproliferation деятельности предположил, что активность находится в фенольных смол с MW<1000Da. Апоптоз массива исследование клеток A2780, получавших повторно показали, что экспрессия ряда генов, регулирующих апоптоз были модулируются лечения. Это исследование показало, что повторное ингибирует пролиферацию яичников раковые клеточные линии, воздействуя на клеточный цикл в несколько этапов. Это индуцированного апоптоза путем изменения экспрессии нескольких генов, регулирующих апоптоз, и имеет потенциал в качестве дополнения к рака химиотерапия.