p21CIP1 Induces Apoptosis via Binding to BCL2 in LNCaP Prostate Cancer Cells Treated with MCS-C3, A Novel Carbocyclic Analog of Pyrrolopyrimidine.

BACKGROUND: Previously, we synthesized a new carbocyclic analog of pyrrolo[2,3-d]pyrimidine nucleoside, designated MCS-C3. Recently, we found that LNCaP androgen-responsive prostate cancer cells treated with MCS-C3 rapidly undergo intrinsic apoptosis through dramatic up-regulation of p21(CIP1). The present study aimed to evaluate the cellular functions and underlying molecular mechanisms of p21(CIP1) on apoptotic induction in LNCaP cells treated with 6 µM MCS-C3. MATERIALS AND METHODS: Western blots, flow cytometric assay, immunoprecipitation, and transmission electron microscopy analysis were used to measure apoptotic induction in 6-µM MCS-C3-treated LNCaP cells. Effects of MCS-C3 on gene expression of p21(CIP1) were measured by semi-quantitative real-time polymerase chain reaction, and small interfering RNA transfection. RESULTS: MCS-C3 induced appreciable caspase-dependent apoptosis associated with the significant up-regulation of p53-dependent p21(CIP1) in LNCaP cells. Moreover, this apoptotic induction was caused by direct binding of p21(CIP1) to anti-apoptotic B-cell lymphoma 2 (BCL2) protein, and antagonizing BCL2 function. In addition, MCS-C3-mediated apoptotic induction, and up-regulation of p21(CIP1) were almost completely blocked by the treatment of androgen-responsive LNCaP cells with flutamide, an androgen receptor (AR) antagonist. CONCLUSION: We identified that induction of intrinsic apoptosis in LNCaP cells by 6 µM MCS-C3 is associated not only with p53 activation but also with mediation of AR. In the present study, we identified the cellular functions and underlying molecular mechanisms of p53-dependent and AR-associated p21(CIP1) on apoptotic induction via direct binding to BCL2 in LNCaP cells treated with 6 µM MCS-C3.

Benzyldihydroxyoctenone, a novel nonsteroidal antiandrogen, shows differential apoptotic induction in prostate cancer cells in response to their androgen responsiveness.

The molecular mechanisms of apoptotic induction by benzyldihydroxyoctenone (BDH), a nonsteroidal antiandrogen, isolated from the culture broth of Streptomyces sp., have been previously published in prostate cancer LNCaP cells. Apoptotic induction of BDH-treated LNCaP cells was associated with downregulation of Bcl-xL that caused, in turn, cytochrome c release from mitochondria, and activation of procaspases and specific proteolytic cleavage of poly(ADP-ribose) polymerase (PARP). The purpose of the present study was to investigate the patterns of apoptotic induction by BDH in non-prostate, ovarian cancer PA-1 (androgen-independent and -insensitive) cells and prostate cancer cells with different androgen responsiveness, such as C4-2 (androgen-independent and -sensitive), 22Rv1 (androgen-dependent and -low sensitive), and LNCaP (androgen-dependent and -high sensitive) cells. We found that BDH-treated LNCaP cell proliferation was significantly inhibited in a time-dependent manner and induced apoptosis via downregulation of the androgen receptor (AR) and prostate-specific antigen (PSA), as well as antiapoptotic Bcl-xL protein. However, the levels of BDH-mediated apoptotic induction and growth inhibition in 22Rv1 cells were apparently lower than those of LNCaP cells. In contrast, the induction of apoptosis and antiproliferative effect in BDH-treated non-prostate cancer PA-1 and hormone refractory C4-2 cells were not detectable and marginal, respectively. Therefore, BDH-mediated differential apoptotic induction and growth inhibition in a cell type seem to be obviously dependent on its androgen responsiveness; primarily on androgen-dependency, and then on androgen sensitivity.

HY251, a novel decahydrocyclopenta[a]indene analog, from Aralia continentalis induces apoptosis via down-regulation of AR expression in human prostate cancer LNCaP cells.

In the course of screening for a novel anticancer drug candidate, we previously isolated HY251 with the molecular structure of 3-propyl-2-vinyl-1,2,3,3a,3b,6,7,7a,8,8a-decahydrocyclopenta[a]indene-3,3a,7a,8a-tetraol from the roots of Aralia continentalis. The current study was designed to evaluate the detailed mechanisms of apoptotic induction of HY251 in androgen-sensitive prostate cancer LNCaP cells. TUNEL assay and Western blot analysis revealed an appreciable apoptotic induction in LNCaP cells treated with 95µM of HY251 for 24h. This apoptotic induction is also associated with cytochrome c release from mitochondria which, in turn, resulted in the activation of caspase-9 and -3, and the cleavage of poly(ADP-ribose) polymerase (PARP). Moreover, we found that HY251 significantly inhibited the expression levels of androgen receptor (AR) and prostate-specific antigen (PSA) in a time-dependent manner, as well as abrogated up-regulation of AR and PSA genes with and without androgen. Therefore, we suggest that HY251, a novel androgen antagonist, may be a potent cancer chemotherapeutic candidate for the treatment of both androgen-sensitive and hormone-refractory prostate cancer.

HY253, a novel decahydrofluorene analog, from Aralia continentalis, induces cell cycle arrest at the G1 phase and cytochrome c-mediated apoptosis in human lung cancer A549 cells.

AIM OF THE STUDY: In the course of our screening for novel modulators on cell cycle progression and apoptosis as anticancer drug candidates, we isolated a novel compound HY253 with the molecular structure of 7,8a-divinyl-2,4a,4b,5,6,7,8,8a,9,9a-decahydro-1H-fluorene-2,4a,4b,9a-tetraol from the roots of Aralia continentalis. This study was designed to evaluate the detailed mechanisms of cell cycle arrest and the apoptotic induction of HY253 in human lung cancer A549 cells. MATERIALS AND METHODS: To investigate the effects of HY253 on cell cycle progression in A549 cells, we measured DNA content of A549 cells treated with 35 microM of HY253 using flow cytometric analysis. Furthermore, TUNEL assay was used to examine apoptotic induction in A549 cells treated with 70 microM of HY253 for 24 and 48 h. The effects of HY253 on apoptosis-associated and cell cycle regulatory proteins in A549 cells were examined using Western blot analysis. RESULTS: The flow cytometric analysis revealed an appreciable G(1) phase arrest in A549 cells treated with 35 microM of HY253. This HY253-induced G(1) phase arrest is associated with decreased expression of cyclin D and up-regulation of p21(CIP1), via p53 phosphorylation at Ser-15, which resulted in increased hypophosphorylated pRb in A549 cells. Furthermore, TUNEL assay and Western blot analysis revealed an appreciable apoptotic induction in A549 cells treated with 70 microM of HY253 for 48 h. This apoptotic induction in HY253-treated A549 cells is also associated with cytochrome c release from mitochondria which in turn resulted in the activation of caspase-9 and -3, and the cleavage of poly(ADP-ribose) polymerase (PARP). CONCLUSIONS: These results demonstrate that HY253, a novel antiproliferative compound isolated from the roots of Aralia continentalis, induces cell cycle arrest at the G(1) phase and apoptosis in A549 cells. Based on these results, we suggest that HY253 may be a potent cancer chemotherapeutic candidate for use in treating human lung cancer cells via up-regulation and activation of p53 gene.

Benzyldihydroxyoctenone, a novel anticancer agent, induces apoptosis via mitochondrial-mediated pathway in androgen-sensitive LNCaP prostate cancer cells.

This study was aimed to evaluate detailed mechanisms on the apoptotic induction of benzyldihydroxyoctenone, a novel compound isolated from Streptomyces sp. KACC91015, in androgen-sensitive LNCaP prostate cancer cells. Benzyldihydroxyoctenone, designated as F3-2-5 in the current study, caused accumulation of apoptotic sub-G(1) phase in the flow cytometric analysis using propidium iodide staining. Moreover, the typical apoptotic DNA fragmentation of the LNCaP cells treated with 30 microM of F3-2-5 was confirmed using the TUNEL assay. This apoptotic induction of F3-2-5 in the LNCaP cells was associated with the cytochrome c release from mitochondria to cytosol, and the activation of procaspase-8, -9, and -3, as well as the specific proteolytic cleavage of poly(ADP-ribose) polymerase (PARP). In addition, F3-2-5 treatment caused the down-regulation of the antiapoptotic protein, such as Bcl-2 and Bcl-X(L), but the proapoptotic protein, such as Bax, was not influenced. To investigate whether apoptotic induction by F3-2-5 is also due to the down-regulation of androgen receptor (AR), Western blot analysis and quantitative RT-PCR were conducted in F3-2-5-treated LNCaP prostate cancer cells. We found that F3-2-5 significantly inhibited the expression levels of AR and prostate-specific antigen (PSA) proteins in a time-dependent manner, as well as F3-2-5 abrogated the up-regulation of AR and PSA genes with and without DHT. Therefore, F3-2-5 has been shown to be an androgen antagonist, suggesting that F3-2-5 could be a potent agent for the treatment of both androgen-dependent and hormone-refractory prostate cancer.

HY251, a novel cell cycle inhibitor isolated from Aralia continentalis, induces G1 phase arrest via p53-dependent pathway in HeLa cells.

This study was aimed to elucidate the novel structure of HY251 isolated from the roots of Aralia continentalis and to evaluate its detailed inhibition mechanisms on cell cycle progression in HeLa cells. The structure of HY251 was elucidated based on the interpretation of the NMR spectra, as 3-propyl-2-vinyl-1,2,3,3a,3b,6,7,7a,8,8a-decahydrocyclopenta[a]indene-3,3a,7a,8a-tetraol. The flow cytometric analysis revealed an appreciable G(1) phase arrest in HeLa cells treated with 100 microM of HY251. This HY251-induced G(1) phase arrest is associated with decreased expression of cyclin D3 and up-regulation of p21(CIP1) and p27(KIP1), via p53 phosphorylation at Ser-15 by transcriptional up-regulation of ATM, which resulted in increased hypophosphorylated pRb in HeLa cells.

HY253, a novel compound isolated from Aralia continentalis, induces apoptosis via cytochrome c-mediated intrinsic pathway in HeLa cells.

This study was aimed to elucidate the novel structure of HY253 isolated from the roots of Aralia continentalis and to evaluate its detailed mechanisms on apoptotic induction in HY253-treated HeLa cells. The structure of HY253 was elucidated based on the interpretation of the NMR spectra, as 7,8a-divinyl-2,4a,4b,5,6,7,8,8a,9,9a-decahydro-1H-fluorene-2,4a,4b,9a-tetraol. The TUNEL assay using flow cytometer revealed an appreciable apoptotic induction in HeLa cells treated with 100 microM of HY253 for 48 h. This apoptotic induction is associated with cytochrome c release from mitochondria, via up-regulation of pro-apoptotic Bcl-2 proteins, such as Bax and Bak, which, in turn, resulted in the activation of caspase-8, -9 and -3, and the cleavage of poly(ADP-ribose) polymerase (PARP).

CR229, a novel derivative of beta-carbolin-1-one, induces cell cycle arrest and apoptosis in HeLa cells via p53 activation.

In the course of screening for novel anticancer compounds, CR229 (6-Bromo-2,3,4,9-tetrahydro-carbolin-1-one), a novel derivative of beta-carbolin-1-one, was generated as a new scaffold candidate. For the first time, the authors demonstrate that CR229 inhibited the growth of HeLa cells by the induction of cell cycle arrest and apoptosis. Analysis of flow cytometry and western blots of HeLa cells treated with 2.5 microM CR229 revealed an appreciable cell cycle arrest in the G1, G2/M phase and apoptotic induction via the p53-dependent pathway. Furthermore, the release of cytochrome c from mitochondria was detected using confocal microscopy in HeLa cells treated with CR229. Accordingly, these data demonstrate that the anticancer activity of CR229 is associated with: (i) the down-regulation of cyclins and cyclin-dependent kinase; (ii) the induction of p53, p21, and p16; and (iii) the activation of caspase-3.