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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

mRNA levels of various genes involved in DNA damage at telomeres in MCF-7 cells. MCF-7 cells were treated chalcone-imidazolone conjugates at a final concentration of 30 μM for 24h. After treatment total RNA was isolated and RT-PCR was conducted. The PCR products were separated on 1% agarose gel electrophoresis and visualized under U.V light. GAPDH was used as loading control. Each experiment was repeated three times. The gel pictures shown here were representative of three independent experiments.
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Figure 12: mRNA levels of various genes involved in DNA damage at telomeres in MCF-7 cells. MCF-7 cells were treated chalcone-imidazolone conjugates at a final concentration of 30 μM for 24h. After treatment total RNA was isolated and RT-PCR was conducted. The PCR products were separated on 1% agarose gel electrophoresis and visualized under U.V light. GAPDH was used as loading control. Each experiment was repeated three times. The gel pictures shown here were representative of three independent experiments.

Mentions: DNA-damaging agents cause cell cycle arrest which ultimately results in apoptosis or senescence and will be regulated by either p53-dependent or independent pathways [27,28]. In order to determine the involvement of p53, p21 and p16 proteins in this event caused by chalcone-imidazolone conjugates, the cells were treated with compounds (TMAC, CA-4, 6 and 8) and Western blot analysis was carried out. The level of p53 protein was found to be down regulated while the levels of p21 and p16 was found to be up-regulated (Figure 6 and 12) particularly in compound 6 and 8 treated MCF-7 cells. The decreased levels of p53 and increased senescence like growth arrest as observed by up-regulation of p21 and p16 proteins clearly shows the lack of involvement of p53 in this event. Our results strongly support the existence of p53 independent pathway in senescence like growth arrest which has been earlier reported [29].


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)

mRNA levels of various genes involved in DNA damage at telomeres in MCF-7 cells. MCF-7 cells were treated chalcone-imidazolone conjugates at a final concentration of 30 μM for 24h. After treatment total RNA was isolated and RT-PCR was conducted. The PCR products were separated on 1% agarose gel electrophoresis and visualized under U.V light. GAPDH was used as loading control. Each experiment was repeated three times. The gel pictures shown here were representative of three independent experiments.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 12: mRNA levels of various genes involved in DNA damage at telomeres in MCF-7 cells. MCF-7 cells were treated chalcone-imidazolone conjugates at a final concentration of 30 μM for 24h. After treatment total RNA was isolated and RT-PCR was conducted. The PCR products were separated on 1% agarose gel electrophoresis and visualized under U.V light. GAPDH was used as loading control. Each experiment was repeated three times. The gel pictures shown here were representative of three independent experiments.
Mentions: DNA-damaging agents cause cell cycle arrest which ultimately results in apoptosis or senescence and will be regulated by either p53-dependent or independent pathways [27,28]. In order to determine the involvement of p53, p21 and p16 proteins in this event caused by chalcone-imidazolone conjugates, the cells were treated with compounds (TMAC, CA-4, 6 and 8) and Western blot analysis was carried out. The level of p53 protein was found to be down regulated while the levels of p21 and p16 was found to be up-regulated (Figure 6 and 12) particularly in compound 6 and 8 treated MCF-7 cells. The decreased levels of p53 and increased senescence like growth arrest as observed by up-regulation of p21 and p16 proteins clearly shows the lack of involvement of p53 in this event. Our results strongly support the existence of p53 independent pathway in senescence like growth arrest which has been earlier reported [29].

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