Quercetin synergistically induces sensitivity to 5-fluorouracil through p53 modulation in colorectal cancer cells

Colorectal tumors (CRC) with microsatellite instability (MSI) show resistance to chemotherapy with 5-fluorouracil (5-FU), the most widely used pharmacological drug for CRC treatment. The aims of this study were to identify compounds that increase sensitivity of MSI CRC cells to 5-FU and characterize their dependence on the p53 status of the cells. Two MSI human CRC derived cell lines were used: CO115 wildtype for p53 and HCT15 that harbors a p53 mutation. The sensitivity of these cells to 5-FU was evaluated by TUNEL assay and the effects on apoptosis induction of co-incubation of the flavonoids, quercetin (Q) or luteolin (L), with 5-FU were characterized. The mechanisms of apoptosis induction were assessed by western blot and p53 mediated effects confirmed by small interference RNA (siRNA) in CO115 and in HCT116 wt and p53 knockout cells. Our results demonstrate that CO115 is more sensitive to 5-FU than the p53 mutated HCT15. Additive effects on apoptosis were shown for L (in both cell lines) and Q (in HCT15). In CO115 Q synergistically induced apoptosis with 5-FU. Apoptosis induction was caspase dependent in CO115 cells but not in HCT15 cells. Both flavonoids increased p53 expression in both cell lines, an effect particularly remarkable for Q. The synergistic effect of Q and 5-FU in CO115 involved the activation of the mitochondrial pathway with an increase in the expression of cleaved caspase 9 and 3 and PARP, as well as a decrease in Bcl-2 expression. Importantly, knockdown of p53 by siRNA in CO115 cells and p53 knockout in HCT116 cells totally abrogated apoptosis induction, demonstrating the dependence on p53 modulation of apoptosis induction by Q. This study suggests the potential applicability of these phytochemicals for enhancement 5-FU efficiency in CRC therapy, especially Q in p53 wild-type tumors.Fundação para a Ciência e a Tecnologia (FCT

The anticarcinogenic potential of dietary natural compounds on colorectal carcinoma : effects on signalling pathways related to proliferation and cell death

Tese de doutoramento em Ciências (área de conhecimento em Biologia)Colorectal cancer (CRC) is the third most prevalent cancer worldwide and the incidence is highly influenced by diet. Epidemiological studies have supported the idea that some dietary food components may influence the risk of CRC through modulation of several biological processes, including proliferation, survival and cell death. The PI3K/Akt and MAP kinases (ERK, JNK and p38) pathways are frequently altered in CRC and components of these pathways are important molecular targets for CRC treatment. Moreover, the apoptotic and non-apoptotic pathways of cell death have been shown good targets for anticancer drugs. The aim of the thesis was to identify potentially anticarcinogenic natural compounds and characterize their effects on signaling pathways related to proliferation and cell death, in CRC cell lines. The role of these natural compounds in combination with 5-fluorouracil (5-FU) was also evaluated. Initially, the anticarcinogenic effect of some water extracts (prepared as a tea) in two human colon carcinoma-derived cell lines, HCT15 and CO115 was studied. In chapter II, we demonstrated the anticarcinogenic activity of Salvia fruticosa (SF) and Salvia officinalis (SO), that seems to be due, at least partially, to the inhibition of the MAPK/ERK pathway, through effects upstream of BRAF. This effect was not due to rosmarinic acid (RA), the major phenolic compound present in these sage plants. In a subsequent study (chapter III), we showed the potential of Hypericum androsaemum (HA) in inhibiting cell proliferation and inducing apoptosis, at least in part, through inhibition of mutant BRAF and PI3K/Akt pathway, as well as, by the induction of p38 and JNK MAP kinases. As in the case of RA also here the main phenolic compound present in HA extract, chlorogenic acid, tested alone did not show any of those effects. Taking into account the previous observations, we further evaluated the potential anticarcinogenic effects of quercetin (Q), luteolin (L) and ursolic acid (UA) in CRC cells. These phenolic compounds (Q and L) and triterpenoid (UA) are present (or appear as derivates) in the water extracts previously used, and have been demonstrated to modulate many steps of the carcinogenic process. In chapter IV, we found that Q and L have antiproliferative and proapoptotic effects that seem to be due, at least in part, to effects on KRAS through regulation of both MAPK/ERK and PI3K pathways. UA demonstrated anticarcinogenic effects by acting on PI3K. In chapter V, we performed a combined study of Q, L and UA with the most common chemotherapeutic agent used in CRC treatment, 5-FU. Resistance to 5-FU arises, especially in tumors with p53 mutations, make combinations with other drugs a necessary strategy to increase 5-FU’s efficacy. In the first part of this study, we demonstrated that Q and L enhanced 5-FU-induced apoptosis and a synergistical effect was observed with Q in the p53 wild type CO115 cells. Q may increase 5-FU-induced apoptosis by modulating the mitochondrial pathway dependent on p53. In the second part, UA was observed to synergistically enhance 5-FU-induced apoptosis in the p53 mutant HCT15 cells. The increase on apoptosis was not dependent on caspases and it was almost completely abrogated by an inhibitor of JNK, suggesting that in these cells UA induces apoptosis through JNK activation. Moreover, the increase of total cell death and the accumulation of LC3, induced by UA, were also dependent on JNK activation. In order to explore the remarkable induction of cell death by UA, which was not all explained by increased apoptosis, we verified the involvement of UA in the autophagic process (chapter VI). Interestingly, we found that UA inhibits autophagy in HCT15 cells at the maturation step, since no fusion events between lysosomes and autophagosomes were detected. Taking advantage of techniques established for MCF-7 breast cancer cells, including the tandem fluorescent construct tagged with LC3 and the measurement of LC3 turnover using a luciferase-based real time assay, the results above were confirmed. Furthermore, UA increased lysosomal membrane permeabilization and decreased the total lysosomal hydrolases activities, indicating a possible impact on lysosomal biogenesis and/or a direct destabilizing effect on lysosomal membranes. In conclusion, this work adds SF, SO and HA to the list of potential plants to use in CRC dietary strategies, as well as, the natural compounds Q, L and UA present in human diet. These natural compounds control CRC progression by modulating important molecular targets, as well as, by enhancement of 5-FU efficiency. UA was the most promising compound, destabilizing the lysosomes and, consequently, inhibiting autophagy, which could sensitize cells to death and thus, may have a possible interest as adjuvant in cancer therapy.O cancro colorectal (CRC) é o terceiro cancro mais comum a nível mundial estando a sua incidência fortemente influenciada pela dieta. Estudos epidemiológicos revelam que compostos presentes na dieta podem influenciar o risco de CRC, modulando vários processos biológicos, incluindo a proliferação, sobrevivência e morte celular. As vias de sinalização PI3K/Akt e MAP kinases (ERK, JNK e p38) estão frequentemente alteradas no CRC e por isso, componentes destas vias constituem alvos moleculares importantes para o seu tratamento. Além disso, as vias apoptóticas e não-apoptóticas de morte celular têm demonstrado ser bons alvos de drogas anticarcinogénicas. A presente tese teve como objectivo identificar compostos naturais com potencial anticarcinogénico e caracterizar os seus efeitos ao nível das vias relacionadas com proliferação e morte celular em linhas de CRC. O papel destes compostos em combinação com o 5- Fluorouracilo (5-FU) foi também abordado. Inicialmente, os efeitos anticarcinogénico de alguns extractos aquosos (preparados como chás) foram estudados em duas linhas celulares humanas de carcinoma do cólon, HCT15 e CO115. No capítulo II, demonstrou-se a actividade anticarcinogénica das plantas Salvia fruticosa (SF) e Salvia officinalis (SO), em que o seu efeito pareceu deverse, pelo menos em parte, à inibição da via MAPK/ERK, através de efeitos a montante do BRAF. O ácido rosmarínico (RA), composto fenólico maioritário presente nas Salvias não foi o responsável pelos efeitos observados. No capítulo III, demonstrou-se que o extracto aquoso de Hypericum androsaemum (HA) é capaz de inibir a proliferação celular e induzir a apoptose, pelo menos em parte, por inibir o BRAF mutado e a via PI3K/Akt, assim como, por induzir as MAP kinases p38 e JNK. Tal como no caso do RA, também o composto fenólico maioritário presente no extracto HA, o ácido clorogénico, testado sózinho, não mostrou nenhum destes efeitos. Tendo em conta os resultados anteriores, foi-se de seguida avaliar o potencial anticarcinogénico da quercetina (Q), luteolina (L) e ácido ursólico (UA). Estes compostos fenólicos (Q e L) e triterpenoide (UA) encontram-se presentes (ou aparecem como derivados) nos extractos aquosos anteriormente estudados, e têm a capacidade em modular várias etapas do processo carcinogénico. No capítulo IV, observou-se o efeito antiproliferativo e pró-apoptótico da Q e L, que foi relacionado, pelo menos em parte, com efeitos no KRAS regulando as vias PI3K e MAPK/ERK. O efeito anticarcinogénico do UA foi observado ao nível do PI3K. No capítulo V, o efeito combinado da Q, L e UA com 5-FU, agente quimioterapêutico mais usado no tratamento do CRC, foi avaliado. O aumento das resistências ao 5-FU, especialmente em tumores com mutações no p53, leva a estratégias de combinações com outras drogas necessárias para aumentar a eficácia do 5-FU. Na primeira parte deste estudo, a Q e a L aumentaram a apoptose induzida pelo 5-FU, e um efeito sinergético foi obtido para a Q nas células CO115 com p53 normal. A Q provavelmente aumentou a apoptose induzida pelo 5-FU através da modulação da via mitocondrial dependente do p53. Na segunda parte, observou-se que UA sinergeticamente aumentou a apoptose induzida pelo 5-FU em células HCT15 com p53 mutado. O aumento da apoptose não foi dependente das caspases e foi quase completamente inibido por um inibidor da JNK, sugerindo que nestas células o UA induz apoptose via activação da JNK. Além disso, o aumento da morte celular total e a acumulação do LC3, induzidos pelo UA, foi também dependente da activação da JNK. Por fim, para explorar o efeito marcante da indução da morte celular pelo UA, na qual não foi totalmente explicado pelo aumento da apoptose, foi estudado o involvimento do UA no processo autofágico (capítulo VI). Interessantemente, verificou-se que o UA inibiu a autofagia nas células HCT15 ao nível da maturação, uma vez que não foi detectado fusão entre lisossomas e autofagossomas. Estes resultados foram confirmados tirando vantagem de técnicas estabelecidas para a linha MCF-7 de cancro da mama, como a construção fluorescente tandem ligado ao LC3 e a medição do turnover do LC3 usando o ensaio de luciferase em tempo real. Adicionalmente, observou-se que UA aumentou a permeabilidade da membrana lisossomal e diminuiu a actividade total das hidrolases lisossomais, indicando um possível impacto na biogénese lisossomal e/ou uma destabilização directa na membrana dos lisossomas. Em conclusão, este trabalho adiciona SF, SO e HA, à lista de potenciais plantas a usar em estratégias alimentares contra o CRC, assim como a Q, L e UA presentes na dieta. Estes compostos naturais controlam a progressão do CRC modulando importantes alvos moleculares e aumentando a eficiência do 5-FU. O UA foi o composto mais promissor, destabilizando os lisossomas e, consequentemente, inibindo a autofagia, e por isso, possuindo elevado interesse como adjuvante na terapia do cancro.Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/27524/2006, co-financiado pelo Programa Operacional Potencial Humano (POPH) do Quadro de Referencia Estratégico Nacional (QREN), comparticipado pelo Fundo Social Europeu e por fundos nacionais

Hypericum androsaemum water extract inhibits proliferation in human colorectal cancer cells through effects on MAP kinases and PI3K/Akt pathway

MAP kinase and PI3K/Akt signalling pathways are commonly altered in colorectal carcinoma (CRC) leading to tumor growth due to increased cell proliferation and inhibition of apoptosis. Several species of the genus Hypericum are used in Portugal to prepare herbal teas to which digestive tract effects are attributed. In the present study, the antiproliferative and proapoptotic effects of the water extracts of H. androsaemum (HA) and H. perforatum (HP) were investigated in two human colon carcinoma-derived cell lines, HCT15 and CO115, which harbour activating mutations of KRAS and BRAF, respectively. Contrarily to HP, HA significantly inhibited cell proliferation and induced apoptosis in both cell lines. HA decreased BRAF and phospho-ERK expressions in CO115, but not in HCT15. HA also decreased Akt phosphorylation in CO115 and induced p38 and JNK in both cell lines. HA induced cell cycle arrest at S and G2/M phases as well as caspase-dependent apoptosis in both cell lines. Chlorogenic acid (CA), the main phenolic compound present in the HA extract and less represented in the HP water extract, did, however, not show any of those effects when used individually. In conclusion, water extract of HA, but not of HP, controlled CRC proliferation and specifically acted on mutant and not wild-type BRAF. The effect of HA was, however, not due to CA alone.CPRX was supported by the Foundation for Science and Technology (FCT), Portugal, through the grant SFRH/BD/27524/2006 and the work was supported by the FCT research grants PTDC/AGR-AAM/70418/2006 (HypericumBiotech) and PEst-C/BIA/UI4050/2011. All projects are co-funded by the program COMPETE from QREN with co-participation from the European Community fund FEDER

Salvia fruticosa, salvia officinalis and rosmarinic acid induce apoptosis and inhibit proliferation of human colorectal cell lines: the role in MAPK/ERK pathway

Epidemiologic studies have shown that nutrition is a key factor in modulating sporadic colorectal carcinoma (CRC) risk. Aromatic plants of the genus Salvia (sage) have been attributed many medicinal properties, which include anticancer activity. In the present study, the antiproliferative and pro-apoptotic effects of water extracts of Salvia fruticosa (SF) and Salvia officinalis (SO) and of their main phenolic compound rosmarinic acid (RA) were evaluated in two human colon carcinoma-derived cell lines, HCT15 and CO115, which have different mutations in the MAPK/ERK and PI3K/Akt signalling pathways. These pathways are commonly altered in CRC leading to increased proliferation and inhibition of apoptosis. Our results show that SF, SO and RA induce apoptosis in both cell lines, whereas cell proliferation was inhibited by the two sage extracts only in HCT15. SO, SF and RA inhibited ERK phosphorylation in HCT15 and had no effects on Akt phosphorylation in CO115 cells. The activity of sage extracts seems to be due, at least in part, to the inhibition of MAPK/ERK pathway.POCI/AGR/62040/2004. CPRX and CFLSFRH/BD/27524/2006 and SFRH/BPD/26316/2006Foundation for Science and Technology (FCT

Ursolic acid, a dietary phytochemical, decreases KRAS signaling and modulates cell death pathways in resistant CRC cells

Publicado em "BMC Proceedings 2012, 6(Suppl 3)"KRAS mutations are frequent in colorectal cancer (CRC) and have the potential to activate proliferation and inhibit cell death through effects on MAPK/ERK and PI3K/Akt signaling pathways. Because diet is one of the most important determinants of CRC incidence and progression, we studied the effects of the dietary triterpenoid ursolic acid (UA) on proliferation and cell death induction in human CRC derived KRAS mutated cell lines. Our results show that UA decreases cell proliferation and induces cell death while decreasing signaling through KRAS as indicated by a decrease in ERK and Akt phosphorylation (western blot). UA also induced cell death. TP53 mutated cells are known to be resistant to the chemotherapeutic drug 5-FU. Caspase independent apoptosis (Tunel assay), was increased 6 fold by co-incubation of UA with 5-FU. However, apoptosis was only a small percentage of the total cell death induced by UA. In order to explain these observations, we looked into effects on autophagy. Autophagy is emerging as a promising therapeutic target for drug resistant tumors. UA modulated autophagy by inducing the accumulation of LC3 II and p62 levels an effect dependent on JNK activation. In conclusion, this study shows UA’s anticancer potential as a modulator of KRAS signaling and cell death mechanisms increasing sensitivity to the chemotherapeutic drug 5-FU

Luteolin, quercetin and ursolic acid are potent inhibitors of proliferation and inducers of apoptosis in both KRAS and BRAF mutated human colorectal cancer cells

KRAS and BRAF mutations are frequent in colorectal carcinoma (CRC) and have the potential to activate proliferation and survival through MAPK/ERK and/or PI3K signalling pathways. Because diet is one of the most important determinants of CRC incidence and progression, we studied the effects of the dietary phytochemicals quercetin (Q), luteolin (L) and ursolic acid (UA) on cell proliferation and apoptosis in two human CRC derived cell lines, HCT15 and CO115, harboring KRAS and BRAF activating mutations, respectively. In KRAS mutated HCT15 cells, Q and L significantly decreased ERK phosphorylation, whereas in BRAF mutated CO115 cells the three compounds decreased Akt phosphorylation but had no effect on phospho-ERK. Our findings show that these natural compounds have antiproliferative and proapoptotic effects and simultaneously seem to act on KRAS and PI3K but not on BRAF. These results shed light on the molecular mechanisms of action of Q, L and UA and emphasize the potential of dietary choices for the control of CRC progression.This work was supported by the Foundation for Science and Technology, Portugal, by the research Grant POCI/AGR/62040/2004. CPRX and CFL were supported by the Foundation for Science and Technology, Portugal, through the Grants SFRH/BD/ 27524/2006 and SFRH/BPD/26316/2006, respectively

Synthesis of Novel Methyl 3-(hetero)arylthieno[3,2-b]pyridine-2-carboxylates and Antitumor Activity Evaluation: Studies In Vitro and In Ovo Grafts of Chick Chorioallantoic Membrane (CAM) with a Triple Negative Breast Cancer Cell Line

A series of novel functionalized methyl 3-(hetero)arylthieno[3,2-b]pyridine-2-carboxylates 2a–2h were synthesized by C-C Pd-catalyzed Suzuki-Miyaura cross-coupling of methyl 3-bromothieno[3,2-b]pyridine-2-carboxylate with (hetero)aryl pinacol boranes, trifluoro potassium boronate salts or boronic acids. Their antitumoral potential was evaluated in two triple negative breast cancer (TNBC) cell lines—MDA-MB-231 and MDA-MB-468, by sulforhodamine B assay. Their effects on the non-tumorigenic MCF-12A cells were also evaluated. The results demonstrated that three compounds caused growth inhibition in both TNBC cell lines, with little or no effect against the non-tumorigenic cells. The most promising compound was further studied concerning possible effects on cell viability (by trypan blue exclusion assay), cell proliferation (by bromodeoxyuridine assay) and cell cycle profile (by flow cytometry). The results demonstrated that the GI50 concentration of compound 2e (13 μM) caused a decreased in MDA-MB-231 cell number, which was correlated with a decreased in the % of proliferating cells. Moreover, this compound increased G0/G1 phase and decreased S phases, when compared to control cells (although was not statistic significant). Interestingly, compound 2e also reduced tumor size using an in ovo CAM (chick chorioallantoic membrane) model. This work highlights the potential antitumor effect of a novel methyl 3-arylthieno[3,2-b]pyridine-2-carboxylate derivative.This research was funded by Fundacao para a Ciencia e Tecnologia (FCT)-Portugal that financially supports CQUM (UID/QUI/686/2019), also financed by European Regional Development Fund (ERDF), COMPETE2020 and Portugal2020, the PTNMR network also supported by Portugal2020. C.P.R.X. is supported through the post-doc grant SFRH/BPD/122871/2016 and J.M.R. through the doctoral grant SFRH/BD/115844/2016, by FCT, ESF (European Social Fund) and HCOP (Human Capital Operational Programme)

Ursolic acid induces cell death and modulates autophagy through JNK pathway in apoptosis-resistant colorectal cancer cells

Colorectal carcinomas (CRCs) with P53 mutations have been shown to be resistant to chemotherapy with 5-fluorouracil (5-FU), the most widely used chemotherapeutic drug for CRC treatment. Autophagy is emerging as a promising therapeutic target for drug-resistant tumors. In the present study, we tested the effects of ursolic acid (UA), a natural triterpenoid, on cell death mechanisms and its effects in combination with 5-FU in the HCT15 p53 mutant apoptosis-resistant CRC cell line. The involvement of UA in autophagy and its in vivo efficacy were evaluated. Our data show that UA induces apoptosis independent of caspases in HCT15 cells and enhances 5-FU effects associated with an activation of c-jun N-terminal kinase (JNK). In this cell line, where this compound has a more pronounced effect on the induction of cell death compared to 5-FU, apoptosis corresponds only to a small percentage of the total cell death induced by UA. UA also modulated autophagy by inducing the accumulation of LC3 and p62 levels with involvement of JNK pathway, which indicates a contribution of autophagy on JNK-dependent induction of cell death by UA. By using nude mice xenografted with HCT15 cells, we verified that UA was also active in vivo decreasing tumor growth rate. In conclusion, this study shows UA's anticancer potential both in vitro and in vivo. Induction of cell death and modulation of autophagy in CRC-resistant cells were shown to involve JNK signaling.C.P.R.X. and D.F.N.P. were supported by the Foundation for Science and Technology (FCT), Portugal, through grants SFRH/BD/27524/2006 and SFRH/BD/64817/2009, respectively. C.P.W. was guest professor at University of Copenhagen through the grant SFRH/BSAB/918/2009. The work was supported by FCT research grants PTDC/QUI-BIQ/101392/2008 (NaturAge) and PEst-C/BIA/UI4050/2011. All projects are co-funded by the program COMPETE from QREN with co-participation from the European Community fund FEDER

Ursolic acid impairs cellular lipid homeostasis and lysosomal membrane integrity in breast carcinoma cells

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/cells11244079/s1, Figure S1: UA kills MCF7 cells partly through apoptosis; Figure S2: UA causes LC3 puncta formation in MCF7 and HCT15 cells; Figure S3: UA causes LMP prior to MOMP and alters lysosomal localization in HeLa cells; Figure S4: Additional lipidomics data; Table S1: List of resources; Table S2: Internal lipid and drug standards; Table S3: Precursor ion, fragment ion, and neutral loss for lipid identification; Table S4: All experiments.Cancer is one of the leading causes of death worldwide, thus the search for new cancer therapies is of utmost importance. Ursolic acid is a naturally occurring pentacyclic triterpene with a wide range of pharmacological activities including anti-inflammatory and anti-neoplastic effects. The latter has been assigned to its ability to promote apoptosis and inhibit cancer cell proliferation by poorly defined mechanisms. In this report, we identify lysosomes as the essential targets of the anti-cancer activity of ursolic acid. The treatment of MCF7 breast cancer cells with ursolic acid elevates lysosomal pH, alters the cellular lipid profile, and causes lysosomal membrane permeabilization and leakage of lysosomal enzymes into the cytosol. Lysosomal membrane permeabilization precedes the essential hallmarks of apoptosis placing it as an initial event in the cascade of effects induced by ursolic acid. The disruption of the lysosomal function impairs the autophagic pathway and likely partakes in the mechanism by which ursolic acid kills cancer cells. Furthermore, we find that combining treatment with ursolic acid and cationic amphiphilic drugs can significantly enhance the degree of lysosomal membrane permeabilization and cell death in breast cancer cells.This work was supported by grants from the Danish National Research Foundation (DNRF125), European Research Council (AdG340751), Danish Cancer Society (R167-A11061) and, Novo Nordisk Foundation (NNF19OC0054296), to M.J., K.M. was supported by the Independent Research Fund Denmark (6108–00542B) and Novo Nordisk Foundation (NNF17OC0029432).info:eu-repo/semantics/publishedVersio

Quercetin enhances 5-fluorouracil-induced apoptosis in MSI colorectal cancer cells through p53 modulation

Purpose: Colorectal tumors (CRC) with microsatellite instability (MSI) show resistance to chemotherapy with 5-fluorouracil (5-FU), the most widely used pharmacological drug for CRC treatment. The aims of this study were to test the ability of quercetin (Q) and luteolin (L) to increase sensitivity of MSI CRC cells to 5-FU and characterize the dependence of the effects on cells´ p53 status. Methods: Two MSI human CRC derived cell lines were used, CO115 wild-type (wt) for p53 and HCT15 that harbors a p53 mutation. Apoptosis induction in these cells by 5-FU, Q and L alone and in combinations were evaluated by TUNEL and western. The dependence on p53 of the effects was confirmed by small interference RNA (siRNA) in CO115 cells and in MSI HCT116 wt and p53 knockout cells. Results: CO115 p53-wt cells are more sensitive to 5-FU than the p53 mutated HCT15. The combination treatment of 5-FU with L and Q increased apoptosis with a significant effect for Q in CO115. Both flavonoids increased p53 expression in both cell lines, an effect particularly remarkable for Q. The significant apoptotic enhancement in CO115 incubated with Q plus 5-FU involved the activation of the apoptotic mitochondrial pathway. Importantly, knockdown of p53 by siRNA in CO115 cells and p53 knockout in HCT116 cells totally abrogated apoptosis induction, demonstrating the dependence of the effect on p53 modulation by Q. Conclusion: This study suggests the potential applicability of these phytochemicals for enhancement 5-FU efficiency in MSI CRC therapy, especially Q in p53 wt tumors.CPRX was supported by the Foundation for Science and Technology (FCT), Portugal, through the grant SFRH/BD/27524/2006 and the work was supported by the FCT research grant PTDC/AGR-AAM/70418/2006