Limits...
Chalcone-imidazolone conjugates induce apoptosis through DNA damage pathway by affecting telomeres.

Ramaiah MJ, Pushpavalli S, Krishna GR, Sarma P, Mukhopadhyay D, Kamal A, Bhadra U, Bhadra MP - Cancer Cell Int. (2011)

Bottom Line: Increased p53BP1 foci by immunolocalisation studies and TRF1 suggested the possible involvement of telomere and associated proteins in the apoptotic event.The apoptotic proteins such as Bax, active caspase-9 and cleaved RB are up-regulated in the compound treated cells revealing the apoptotic nature of the compounds.In summary, chalcone-imidazolone conjugates displayed significant DNA damage activity particularly at telomeres and caused both apoptosis and senescence-like growth arrest which suggested that these compounds have potential activity against breast carcinoma.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Chemical Biology, Indian Institute of Chemical Technology, Tarnaka, Hyderabad-500607, India. ahmedkamal@iict.res.in.

ABSTRACT

Background: Breast cancer is one of the most prevalent cancers in the world and more than one million women are diagnosed leading to 410,000 deaths every year. In our previous studies new chalcone-imidazolone conjugates were prepared and evaluated for their anticancer activity in a panel of 53 human tumor cell lines and the lead compounds identified were 6 and 8. This prompted us to investigate the mechanism of apoptotic event.

Results: Involvement of pro-apoptotic protein (Bax), active caspase-9 and cleavage of retinoblastoma protein was studied. Interestingly, the compounds caused upregulation of p21, check point proteins (Chk1, Chk2) and as well as their phosphorylated forms which are known to regulate the DNA damage pathway. Increased p53BP1 foci by immunolocalisation studies and TRF1 suggested the possible involvement of telomere and associated proteins in the apoptotic event. The telomeric protein such as TRF2 which is an important target for anticancer therapy against human breast cancer was extensively studied along with proteins involved in proper functioning of telomeres.

Conclusions: The apoptotic proteins such as Bax, active caspase-9 and cleaved RB are up-regulated in the compound treated cells revealing the apoptotic nature of the compounds. Down regulation of TRF2 and upregulation of the TRF1 as well as telomerase assay indicated the decrease in telomeric length revealing telomeric dysfunction and thereby controlling the rapid rate of cell proliferation. In summary, chalcone-imidazolone conjugates displayed significant DNA damage activity particularly at telomeres and caused both apoptosis and senescence-like growth arrest which suggested that these compounds have potential activity against breast carcinoma.

No MeSH data available.


Related in: MedlinePlus

Effect of chalcone-imidazolone conjugates in causing DNA fragmentation in MCF-7 cells. MCF-7 cells were treated with compounds TMAC, CA-4, 6 and 8 at a concentration of 30 μM for a period of 24 h. The fragmented DNA was bind to antibody conjugated to FITC. The fluorescence was detected and imaged using confocal microscope. Untreated control cells, were not apoptotic and did not exhibit DNA fragmentation, where as the apoptotic cells in the compound treated condition show green coloured staining. The extent of apoptosis can be visualized by green staining and depicts the extent of DNA fragmentation. Here C denotes control untreated cells.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3094261&req=5

Figure 2: Effect of chalcone-imidazolone conjugates in causing DNA fragmentation in MCF-7 cells. MCF-7 cells were treated with compounds TMAC, CA-4, 6 and 8 at a concentration of 30 μM for a period of 24 h. The fragmented DNA was bind to antibody conjugated to FITC. The fluorescence was detected and imaged using confocal microscope. Untreated control cells, were not apoptotic and did not exhibit DNA fragmentation, where as the apoptotic cells in the compound treated condition show green coloured staining. The extent of apoptosis can be visualized by green staining and depicts the extent of DNA fragmentation. Here C denotes control untreated cells.

Mentions: In order to understand the apoptosis inducing ability of the compounds TUNEL assay was conducted. The data revealed that DNA fragmentation was more prominent in compound 6 treated cells rather than in the case of the starting material TMAC (Figure 2). The apoptotic inducing nature of the compound was further validated by Trypan blue exclusion assay on cell viability. We observed that compound 6 and 8 treated cells to be less viable than control untreated cells, positive control (CA-4) and starting material (TMAC) (Figure 3). Blebbing, the characteristic feature of apoptosis was also clearly observed by nuclear staining with DNA dye DAPI in compound 6 and 8 after 24 h of compound treatment (Figure 4).


Chalcone-imidazolone conjugates induce apoptosis through DNA damage pathway by affecting telomeres.

Ramaiah MJ, Pushpavalli S, Krishna GR, Sarma P, Mukhopadhyay D, Kamal A, Bhadra U, Bhadra MP - Cancer Cell Int. (2011)

Effect of chalcone-imidazolone conjugates in causing DNA fragmentation in MCF-7 cells. MCF-7 cells were treated with compounds TMAC, CA-4, 6 and 8 at a concentration of 30 μM for a period of 24 h. The fragmented DNA was bind to antibody conjugated to FITC. The fluorescence was detected and imaged using confocal microscope. Untreated control cells, were not apoptotic and did not exhibit DNA fragmentation, where as the apoptotic cells in the compound treated condition show green coloured staining. The extent of apoptosis can be visualized by green staining and depicts the extent of DNA fragmentation. Here C denotes control untreated cells.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3094261&req=5

Figure 2: Effect of chalcone-imidazolone conjugates in causing DNA fragmentation in MCF-7 cells. MCF-7 cells were treated with compounds TMAC, CA-4, 6 and 8 at a concentration of 30 μM for a period of 24 h. The fragmented DNA was bind to antibody conjugated to FITC. The fluorescence was detected and imaged using confocal microscope. Untreated control cells, were not apoptotic and did not exhibit DNA fragmentation, where as the apoptotic cells in the compound treated condition show green coloured staining. The extent of apoptosis can be visualized by green staining and depicts the extent of DNA fragmentation. Here C denotes control untreated cells.
Mentions: In order to understand the apoptosis inducing ability of the compounds TUNEL assay was conducted. The data revealed that DNA fragmentation was more prominent in compound 6 treated cells rather than in the case of the starting material TMAC (Figure 2). The apoptotic inducing nature of the compound was further validated by Trypan blue exclusion assay on cell viability. We observed that compound 6 and 8 treated cells to be less viable than control untreated cells, positive control (CA-4) and starting material (TMAC) (Figure 3). Blebbing, the characteristic feature of apoptosis was also clearly observed by nuclear staining with DNA dye DAPI in compound 6 and 8 after 24 h of compound treatment (Figure 4).

Bottom Line: Increased p53BP1 foci by immunolocalisation studies and TRF1 suggested the possible involvement of telomere and associated proteins in the apoptotic event.The apoptotic proteins such as Bax, active caspase-9 and cleaved RB are up-regulated in the compound treated cells revealing the apoptotic nature of the compounds.In summary, chalcone-imidazolone conjugates displayed significant DNA damage activity particularly at telomeres and caused both apoptosis and senescence-like growth arrest which suggested that these compounds have potential activity against breast carcinoma.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Chemical Biology, Indian Institute of Chemical Technology, Tarnaka, Hyderabad-500607, India. ahmedkamal@iict.res.in.

ABSTRACT

Background: Breast cancer is one of the most prevalent cancers in the world and more than one million women are diagnosed leading to 410,000 deaths every year. In our previous studies new chalcone-imidazolone conjugates were prepared and evaluated for their anticancer activity in a panel of 53 human tumor cell lines and the lead compounds identified were 6 and 8. This prompted us to investigate the mechanism of apoptotic event.

Results: Involvement of pro-apoptotic protein (Bax), active caspase-9 and cleavage of retinoblastoma protein was studied. Interestingly, the compounds caused upregulation of p21, check point proteins (Chk1, Chk2) and as well as their phosphorylated forms which are known to regulate the DNA damage pathway. Increased p53BP1 foci by immunolocalisation studies and TRF1 suggested the possible involvement of telomere and associated proteins in the apoptotic event. The telomeric protein such as TRF2 which is an important target for anticancer therapy against human breast cancer was extensively studied along with proteins involved in proper functioning of telomeres.

Conclusions: The apoptotic proteins such as Bax, active caspase-9 and cleaved RB are up-regulated in the compound treated cells revealing the apoptotic nature of the compounds. Down regulation of TRF2 and upregulation of the TRF1 as well as telomerase assay indicated the decrease in telomeric length revealing telomeric dysfunction and thereby controlling the rapid rate of cell proliferation. In summary, chalcone-imidazolone conjugates displayed significant DNA damage activity particularly at telomeres and caused both apoptosis and senescence-like growth arrest which suggested that these compounds have potential activity against breast carcinoma.

No MeSH data available.


Related in: MedlinePlus