Presented By: Arsen KhachatryanPresented By: Arsen Khachatryan

6-[3-(1-adamantyl)-4-hydroxyphenyl]-2-naphthalene carboxylic acid, a synthetic retinoid, is more commonly and thankfully called CD437 which is known to induce apoptosis in a variety of cancer cells including lung cancer cells. CD437 has been proven to be highly sensitive in cancer cells with wild-type p53 and because normal cells have p53 also a question arose as to whether they are sensitive to CD437 induced apoptosis as well. To answer this question the paper studied the effects of CD437 on apoptosis induction and the expression of several p53 regulated apoptosis related genes between human lung cancer cells and normal human epithelial cells containing wild-type p53.

6-[3-(1-adamantyl)-4-hydroxyphenyl]-2-naphthalene carboxylic acid, a synthetic retinoid, is more commonly and thankfully called CD437 which is known to induce apoptosis in a variety of cancer cells including lung cancer cells. CD437 has been proven to be highly sensitive in cancer cells with wild-type p53 and because normal cells have p53 also a question arose as to whether they are sensitive to CD437 induced apoptosis as well. To answer this question the paper studied the effects of CD437 on apoptosis induction and the expression of several p53 regulated apoptosis related genes between human lung cancer cells and normal human epithelial cells containing wild-type p53.

Retinoids are the family of vitamin A derivatives both natural and synthetic which regulate a broad range of biological processes, including growth, differentiation, and development, in both normal and neoplastic cells. Their effects are mediated by two classes of nuclear receptors the RARs and the RXRs which are members of the steroid and thyroid hormone receptor superfamily.

Retinoids are the family of vitamin A derivatives both natural and synthetic which regulate a broad range of biological processes, including growth, differentiation, and development, in both normal and neoplastic cells. Their effects are mediated by two classes of nuclear receptors the RARs and the RXRs which are members of the steroid and thyroid hormone receptor superfamily.

• p53 is a tumor-suppressor protein that induces apoptotic cell death in response to oncogenic stress. Malignant progression is dependent on loss of p53 function, either through mutation in the TP53 gene, which encodes p53, or by defects in the signaling pathways that are upstream or downstream of p53.

• Mutations in TP53 occur in more than half of all human cancers, resulting in the expression of mutant p53.

• Besides apoptosis, cell-cycle arrest activities are also regulated by p53 associated pathways.

• Phosphorylation of p53 regulates its ability to activate the

expression of apoptotic target genes.

• p53 is a tumor-suppressor protein that induces apoptotic cell death in response to oncogenic stress. Malignant progression is dependent on loss of p53 function, either through mutation in the TP53 gene, which encodes p53, or by defects in the signaling pathways that are upstream or downstream of p53.

• Mutations in TP53 occur in more than half of all human cancers, resulting in the expression of mutant p53.

• Besides apoptosis, cell-cycle arrest activities are also regulated by p53 associated pathways.

• Phosphorylation of p53 regulates its ability to activate the

expression of apoptotic target genes.

In the United States, lung cancer is the leading cause of cancer mortality among both men and women. It has been estimated that there will be 185,000 new cases and 169,000 deaths from lung cancer in 2005. Due to the severe morbidity of lung cancer and poor survival rate, intense efforts are being mounted to find effective new agents and treatments against lung cancer. CD437 has shown great potential and promise for prevention or treatment of certain types of cancer cells by inducing apoptosis in a variety of neoplastic cell types, also showing promise in vivo with animal xenograft models.

In the United States, lung cancer is the leading cause of cancer mortality among both men and women. It has been estimated that there will be 185,000 new cases and 169,000 deaths from lung cancer in 2005. Due to the severe morbidity of lung cancer and poor survival rate, intense efforts are being mounted to find effective new agents and treatments against lung cancer. CD437 has shown great potential and promise for prevention or treatment of certain types of cancer cells by inducing apoptosis in a variety of neoplastic cell types, also showing promise in vivo with animal xenograft models.

CD437 can selectively bind to and transactivate the RAR γ mediated pathway for apoptosis, but it is thought that CD437 induces apoptosis in human lung cancer cells through both p53 dependent and independent pathways, depending on whether the cells have wild-type p53. CD437 increased the level of p53 protein and also increased the expression of p53 regulated genes such as Bax, Fas, and DR5, which triggered apoptosis through induction of cytochrome c release from mitochondria and caspase-3 activation. Human lung cancer cells are so extremely sensitive to CD437 induced apoptosis that a study needed to be done to address its risk to normal human lung epithelial cells. This study showed that CD437 can selectively induce apoptosis in human lung cancer cells while sparing normal cells. In addition, CD437 exhibited differential modulation of several p53 regulated genes between the two types of cells.

CD437 can selectively bind to and transactivate the RAR γ mediated pathway for apoptosis, but it is thought that CD437 induces apoptosis in human lung cancer cells through both p53 dependent and independent pathways, depending on whether the cells have wild-type p53. CD437 increased the level of p53 protein and also increased the expression of p53 regulated genes such as Bax, Fas, and DR5, which triggered apoptosis through induction of cytochrome c release from mitochondria and caspase-3 activation. Human lung cancer cells are so extremely sensitive to CD437 induced apoptosis that a study needed to be done to address its risk to normal human lung epithelial cells. This study showed that CD437 can selectively induce apoptosis in human lung cancer cells while sparing normal cells. In addition, CD437 exhibited differential modulation of several p53 regulated genes between the two types of cells.

• Cell Lines Cancerous Cell Lines H460 (Large cell carcinoma) H292 (Mucoepidermoid carcinoma) Normal Cell Lines NHBE (Normal human bronchial epithelial) SAEC (Small airway epithelial cells)

• Methods Growth Inhibition Assays DNA Fragmentation Assays Northern Blot Analysis Western Blot Analysis

• Cell Lines Cancerous Cell Lines H460 (Large cell carcinoma) H292 (Mucoepidermoid carcinoma) Normal Cell Lines NHBE (Normal human bronchial epithelial) SAEC (Small airway epithelial cells)

• Methods Growth Inhibition Assays DNA Fragmentation Assays Northern Blot Analysis Western Blot Analysis

In this study the effects of CD437 were tested on cells cultures both in the presence of serum and with the absence of serum. It was shown that the serum in the cell culture effected the results and the effectiveness of CD437 induced apoptosis. Both H292 and H460 were super-sensitive in serum free culture conditions. In the presence of 5% serum, CD437 inhibited cell growth by 30-80% in both lung cancer cell lines treated with 0.2-1µM of CD437. It showed weak or no growth in both the NHBE and SAEC cell lines with less than 30% inhibition with 1 µM of CD437. In the absence of serum even with 0.2 µM CD437, growth of the H460 and H292 cell lines were inhibited by more than 60%, with more than 25% inhibition at 0.05 µM. Normal lung epithelial cells were less responsive with less than 20% inhibition.

In this study the effects of CD437 were tested on cells cultures both in the presence of serum and with the absence of serum. It was shown that the serum in the cell culture effected the results and the effectiveness of CD437 induced apoptosis. Both H292 and H460 were super-sensitive in serum free culture conditions. In the presence of 5% serum, CD437 inhibited cell growth by 30-80% in both lung cancer cell lines treated with 0.2-1µM of CD437. It showed weak or no growth in both the NHBE and SAEC cell lines with less than 30% inhibition with 1 µM of CD437. In the absence of serum even with 0.2 µM CD437, growth of the H460 and H292 cell lines were inhibited by more than 60%, with more than 25% inhibition at 0.05 µM. Normal lung epithelial cells were less responsive with less than 20% inhibition.

Cell numbers were determined by growth inhibition SRB assays. It is thought that the proteins in the serum such as albumin, bind CD437 and decrease the free concentration of CD437 with access to the cells.

Cell numbers were determined by growth inhibition SRB assays. It is thought that the proteins in the serum such as albumin, bind CD437 and decrease the free concentration of CD437 with access to the cells.

Since the doubling times of all the cells used for this study are around 24 hours, they were treated for 24 hours allowing the cells to divide only once or less. This is important in order to show that the effects of CD437 on the growth of lung cancer cells are not attributed to blockage of cell proliferation, but rather to apoptosis.

Lung cancer cells treated with CD437 underwent morphological changes characteristic of apoptosis, such as rounding, detachment, and floating, while normal lung epithelial cells did not change their morphology, but showed a slight decrease in cell number. This shows that CD437 selectively induces apoptosis in cancerous lung cells, but not in normal lung epithelial cells.

Since the doubling times of all the cells used for this study are around 24 hours, they were treated for 24 hours allowing the cells to divide only once or less. This is important in order to show that the effects of CD437 on the growth of lung cancer cells are not attributed to blockage of cell proliferation, but rather to apoptosis.

Lung cancer cells treated with CD437 underwent morphological changes characteristic of apoptosis, such as rounding, detachment, and floating, while normal lung epithelial cells did not change their morphology, but showed a slight decrease in cell number. This shows that CD437 selectively induces apoptosis in cancerous lung cells, but not in normal lung epithelial cells.

Cells were treated with indicated concentrations of CD437 under optimal conditions for NHBE without serum and for H460 with serum. In B the H460 cell line is in a suboptimal culture condition without serum. It is plain to see that CD437 had a dramatic effect on the cancerous lung cell line H460 regardless of presence of serum.

Cells were treated with indicated concentrations of CD437 under optimal conditions for NHBE without serum and for H460 with serum. In B the H460 cell line is in a suboptimal culture condition without serum. It is plain to see that CD437 had a dramatic effect on the cancerous lung cell line H460 regardless of presence of serum.

CD437 induced a concentration dependant increase in DNA fragments in both lung cancer cell lines. Similar to the growth inhibitory effects, serum free culture condition have made cancer cells more sensitive to CD437 induced apoptosis. 0.2 and even 0.05 µM CD437 were enough to increase DNA fragmentation in the cancer cell lines. Even with 1 µM CD437 there was no increase in DNA fragmentation in the normal lung epithelial cells both in the presence and absence of serum. This further proves that CD437 induces apoptosis in lung cancer cells but not in there normal counterparts.

CD437 induced a concentration dependant increase in DNA fragments in both lung cancer cell lines. Similar to the growth inhibitory effects, serum free culture condition have made cancer cells more sensitive to CD437 induced apoptosis. 0.2 and even 0.05 µM CD437 were enough to increase DNA fragmentation in the cancer cell lines. Even with 1 µM CD437 there was no increase in DNA fragmentation in the normal lung epithelial cells both in the presence and absence of serum. This further proves that CD437 induces apoptosis in lung cancer cells but not in there normal counterparts.

DNA fragmentation was determined using the ELISA methodDNA fragmentation was determined using the ELISA method

The activation of the caspase cascades is the biological hallmark of apoptosis, so it was important to compare the effect of CD437 between normal lung epithelial cells and lung cancer cells. There are two types of caspases: upstream caspases called initiator caspases, such as caspase-8 and -9, and downstream caspases known as effector caspases, such as caspase-3 and -6. The cancer cells when treated with CD437 induced the activation of caspase-8 and -9, which are initiator caspases. This led to Bid protein, a target substrate of caspase-8 to be cleaved. The activation of effector caspases -6 and -3 were also detected, indicated by the increased cleavage of PARP,DFF45 and lamin protein. No caspase activity was observed with the normal lung epithelial cells.

The activation of the caspase cascades is the biological hallmark of apoptosis, so it was important to compare the effect of CD437 between normal lung epithelial cells and lung cancer cells. There are two types of caspases: upstream caspases called initiator caspases, such as caspase-8 and -9, and downstream caspases known as effector caspases, such as caspase-3 and -6. The cancer cells when treated with CD437 induced the activation of caspase-8 and -9, which are initiator caspases. This led to Bid protein, a target substrate of caspase-8 to be cleaved. The activation of effector caspases -6 and -3 were also detected, indicated by the increased cleavage of PARP,DFF45 and lamin protein. No caspase activity was observed with the normal lung epithelial cells.

Activation of these caspases were detected by Western Blot analysis as a decrease of procaspase forms or an appearance of their cleaved bonds along with the cleavage of their target substrates.

Activation of these caspases were detected by Western Blot analysis as a decrease of procaspase forms or an appearance of their cleaved bonds along with the cleavage of their target substrates.

P53 dependant induction of apoptosis and growth arrest by CD437 in human lung cancer cells involves p53 activation and up-regulation of its downstream regulated genes including p21, Bax, DR5 and Fas. The lung cancer cell lines and the normal cells were treated with CD437 and the outcome showed that p53 protein was increased greatly in the two lung cancer cell lines while having little to no effect on normal lung epithelial cells. An increased expression of Bax and DR5 were also present in both H460 and H292 cell line, while showing no effect in normal cells. The same was true for the expression of Fas and DR4. P21 was expressed in both the cancerous cells and the normal cells.

P53 dependant induction of apoptosis and growth arrest by CD437 in human lung cancer cells involves p53 activation and up-regulation of its downstream regulated genes including p21, Bax, DR5 and Fas. The lung cancer cell lines and the normal cells were treated with CD437 and the outcome showed that p53 protein was increased greatly in the two lung cancer cell lines while having little to no effect on normal lung epithelial cells. An increased expression of Bax and DR5 were also present in both H460 and H292 cell line, while showing no effect in normal cells. The same was true for the expression of Fas and DR4. P21 was expressed in both the cancerous cells and the normal cells.

The basal mRNA levels of DcR1 and Dcr2, two decoy receptors for the death ligand TRAIL, which prevent its action, were very low and not inducible by CD437 in the cancerous cell lines. Interestingly, their levels were higher in both normal lung epithelial cells and their mRNA expression was induced by CD437.

Analysis was conducted using the Northern Blot method.

The basal mRNA levels of DcR1 and Dcr2, two decoy receptors for the death ligand TRAIL, which prevent its action, were very low and not inducible by CD437 in the cancerous cell lines. Interestingly, their levels were higher in both normal lung epithelial cells and their mRNA expression was induced by CD437.

Analysis was conducted using the Northern Blot method.

Bcl-2 and Bcl-XL expression is related to the resistance to apoptosis, so it would be helpful to see if they play a roll in the resistance of normal lung epithelial cells to CD437 induced apoptosis. The expression levels of Bcl-2 and Bcl-XL were compared in the absence and presence of CD437 both in the normal lung epithelium and the lung cancer cells.

The basal levels of Bcl-2 and Bcl-XL were very low in the normal lung epithelium and high in the lung cancer cells, yet the cancer cells are sensitive to CD437 while the normal cells are not. CD437 does not change the level of Bcl-2 or Bcl-XL, therefore it cannot account for the resistance of the normal lung epithelium to CD437 induced apoptosis.

Bcl-2 and Bcl-XL expression is related to the resistance to apoptosis, so it would be helpful to see if they play a roll in the resistance of normal lung epithelial cells to CD437 induced apoptosis. The expression levels of Bcl-2 and Bcl-XL were compared in the absence and presence of CD437 both in the normal lung epithelium and the lung cancer cells.

The basal levels of Bcl-2 and Bcl-XL were very low in the normal lung epithelium and high in the lung cancer cells, yet the cancer cells are sensitive to CD437 while the normal cells are not. CD437 does not change the level of Bcl-2 or Bcl-XL, therefore it cannot account for the resistance of the normal lung epithelium to CD437 induced apoptosis.

H460 transfectants with different expression levels of exogenous Bcl-2 were also treated with CD437 to further assess the effects of Bcl-2 on the action CD437. Two Bcl-2 transfected H460 cell lines H460-Bcl-2-6 and H460-Bcl-2-8 were not less sensitive to CD437 than vector-tranfected control cells H460-Neo. They actually turned out to be even more sensitive.

H460 transfectants with different expression levels of exogenous Bcl-2 were also treated with CD437 to further assess the effects of Bcl-2 on the action CD437. Two Bcl-2 transfected H460 cell lines H460-Bcl-2-6 and H460-Bcl-2-8 were not less sensitive to CD437 than vector-tranfected control cells H460-Neo. They actually turned out to be even more sensitive.

The most critical question related to potential applications of proapoptotic agents or any cancer medication for that matter, which can seriously be considered in fighting cancer, is whether they can distinguish between normal and malignant cells. In this study the effects of the synthetic retinoid CD437,and its role in the induction of apoptosis, were compared and contrasted in human lung cancer cells containing wild-type p53 and normal human lung epithelial cells.

We saw that the two lung cancer cell lines underwent rapid apoptosis, evidenced by the typical morphological changes, the activation of the caspase cascades, increased DNA fragmentation, and the increased expression of p53 and its upstream and downstream regulated genes after exposure to CD437.

The most critical question related to potential applications of proapoptotic agents or any cancer medication for that matter, which can seriously be considered in fighting cancer, is whether they can distinguish between normal and malignant cells. In this study the effects of the synthetic retinoid CD437,and its role in the induction of apoptosis, were compared and contrasted in human lung cancer cells containing wild-type p53 and normal human lung epithelial cells.

We saw that the two lung cancer cell lines underwent rapid apoptosis, evidenced by the typical morphological changes, the activation of the caspase cascades, increased DNA fragmentation, and the increased expression of p53 and its upstream and downstream regulated genes after exposure to CD437.

Using the same criteria for evaluation of apoptosis, we discovered that CD437 did not induce cell death in the two normal human lung epithelial cells, proving the it can differentiate among normal and malignant cells. CD437 has also been proven to induce apoptosis in malignant human epidermal keratinocytes and human prostate cancer cells without inducing apoptosis on their normal counterparts.

Using the same criteria for evaluation of apoptosis, we discovered that CD437 did not induce cell death in the two normal human lung epithelial cells, proving the it can differentiate among normal and malignant cells. CD437 has also been proven to induce apoptosis in malignant human epidermal keratinocytes and human prostate cancer cells without inducing apoptosis on their normal counterparts.

Lung Cancer Cells

•Induces visible morphological changes.

•Increase in DNA fragmentation, indicating apoptosis.

•Activation of caspase cascades. Caspase-3 required.

•Presence of high levels of Bcl-2.

•No increase of DcR1 and DcR2.

Normal Lung Epithelium

•No morphological changes.

•No DNA fragmentation.

•No caspase cascade activation.

•Very low levels of Bcl-2

•Increase of DcR1 and Dcr2.

1. Greenlee, R. T., Hill-Harmon, M. B., Murray, T., and Thun, M. Cancer Statistics,2001. CA Cancer J. Clin., 51: 15–36, 2001.2. Sun, S-Y., and Lotan, R. Retinoids and their receptors in cancer development andchemoprevention. Crit. Rev. Oncol/Hematol., 41: 41–55, 2002.3. Shao, Z-M., Dawson, M. I., Li, X. S., Rishi, A. K., Sheik, M. S., Han, Q-X., Ordonez,J. V., Shoot, B., and Fontana, J. A. p53 independent G0/G1 arrest and apoptosisinduced by a novel retinoid in human breast cancer cells. Oncogene, 11: 493–504,1995.4. Schadendorf, D., Kern, M. A., Artuc, M., Pahl, H. L., Rosenbach, T., Fichtner, I.,Nurnberg, W., Stuting, S., Stebut, E. V., Worm, M., Makki, A., Jurgovsky, K., Kolde,G., and Henz, B. M. Treatment of melanoma cells with the synthetic retinoid CD437induces apoptosis via activation of AP-1 in vitro and causes growth inhibition inxenografts in vivo. J. Cell Biol., 135: 1889–1898, 1996.5. Oridate, N., Higuchi, M., Suzuki, S., Shroot, B., Hong, W. K., and Lotan, R. Rapidinduction of apoptosis in human C33A cervical carcinoma cells by the synthetic retinoid6[3-(1-adamantyl)-4-hydroxyphenyl]-2-naphthalene carboxylic acid (CD437). Int. J. Cancer,70: 484–487, 1997.6. Langdon, S. P., Rabiasz, G. J., Ritchie, A. A., Reichert, U., Buchan, P., Miller, W. R.,and Smyth, J. F. Growth-inhibitory effects of the synthetic retinoid CD437 againstovarian carcinoma models in vitro and in vivo. Cancer Chemother. Pharmacol., 42:429–432, 1998.7. Hsu, C. A., Rishi, A. K., Li, X-S., Gerald, T. M., Dawson, M. I., Schiffer, C.,Reichert, U., Shroot, B., Poirer, G. C., and Fontana, J. A. Retinoid induced apoptosisin leukemia cells through a retinoic acid nuclear receptor-independent pathway.Blood, 89: 4470–4479, 1997.

1. Greenlee, R. T., Hill-Harmon, M. B., Murray, T., and Thun, M. Cancer Statistics,2001. CA Cancer J. Clin., 51: 15–36, 2001.2. Sun, S-Y., and Lotan, R. Retinoids and their receptors in cancer development andchemoprevention. Crit. Rev. Oncol/Hematol., 41: 41–55, 2002.3. Shao, Z-M., Dawson, M. I., Li, X. S., Rishi, A. K., Sheik, M. S., Han, Q-X., Ordonez,J. V., Shoot, B., and Fontana, J. A. p53 independent G0/G1 arrest and apoptosisinduced by a novel retinoid in human breast cancer cells. Oncogene, 11: 493–504,1995.4. Schadendorf, D., Kern, M. A., Artuc, M., Pahl, H. L., Rosenbach, T., Fichtner, I.,Nurnberg, W., Stuting, S., Stebut, E. V., Worm, M., Makki, A., Jurgovsky, K., Kolde,G., and Henz, B. M. Treatment of melanoma cells with the synthetic retinoid CD437induces apoptosis via activation of AP-1 in vitro and causes growth inhibition inxenografts in vivo. J. Cell Biol., 135: 1889–1898, 1996.5. Oridate, N., Higuchi, M., Suzuki, S., Shroot, B., Hong, W. K., and Lotan, R. Rapidinduction of apoptosis in human C33A cervical carcinoma cells by the synthetic retinoid6[3-(1-adamantyl)-4-hydroxyphenyl]-2-naphthalene carboxylic acid (CD437). Int. J. Cancer,70: 484–487, 1997.6. Langdon, S. P., Rabiasz, G. J., Ritchie, A. A., Reichert, U., Buchan, P., Miller, W. R.,and Smyth, J. F. Growth-inhibitory effects of the synthetic retinoid CD437 againstovarian carcinoma models in vitro and in vivo. Cancer Chemother. Pharmacol., 42:429–432, 1998.7. Hsu, C. A., Rishi, A. K., Li, X-S., Gerald, T. M., Dawson, M. I., Schiffer, C.,Reichert, U., Shroot, B., Poirer, G. C., and Fontana, J. A. Retinoid induced apoptosisin leukemia cells through a retinoic acid nuclear receptor-independent pathway.Blood, 89: 4470–4479, 1997.

8. Adachi, H., Preston, G., Harvat, B., Dawson, M. I., and Jetten, A. Inhibition of cellproliferation and induction of apoptosis by the retinoid AHPN in human lungcarcinoma cells. Am. J. Respir. Cell Mol., 18: 823–333, 1998.9. Li, Y., Lin, B., Agadir, A., Liu, R., Dawson, M. I., Reed, J. C., Fontana, J. A., Bost,F., Hobbs, P. D., Zheng, Y., Chen, G-Q., Shroot, B., Mercola, D., and Zhang, X-K.Molecular determination of AHPN (CD437)-induced growth arrest and apoptosis inhuman lung cancer cell lines. Mol. Cell. Biol., 18: 4719–4731, 1998.10. Sun, S-Y., Yue, P., Shroot, B., Hong, W. K., and Lotan, R. Induction of apoptosis inhuman non-small cell lung carcinoma cells by a novel synthetic retinoid CD437.J. Cell. Physiol., 173: 279–284, 1997.11. Bernard, B. A., Bernardon, J-M., Delescluse, C., Martin, B., Lenoir, M-C., Margnan,J., Charpentier, B., Pilgrim, W. R., Reichert, U., and Shroot, B. Identification ofsynthetic retinoids with selectivity for human nuclear retinoic acid receptor .Biochem. Biophys. Res. Commun., 186: 977–983, 1992.12. Sun, S-Y., Yue, P., Wu, G. S., El-Deiry, W. S., Shroot, B., Hong, W. K., and Lotan,R. Mechanisms of apoptosis induced by the synthetic retinoid CD437 in humannon-small cell lung carcinoma cells. Oncogene, 18: 2357–2365, 1999.13. Sun, S-Y., Yue, P., Wu, G. S., El-Deiry, W. S., Shroot, B., Hong, W. K., and Lotan,R. Implication of p53 in growth arrest and apoptosis induced by the synthetic retinoidCD437 in human lung cancer cells. Cancer Rec., 59: 2829–2833, 1999.14. Sun, S. Y., Yue, P., Hong, W. K., and Lotan, R. Induction of Fas expression andaugmentation of Fas/Fas ligand-mediated apoptosis by the synthetic retinoid CD437in human lung cancer cells. Cancer Res., 60: 6537–6543, 2000.15. Sun, S-Y., Yue, P., Shroot, B., Michel, S., Dawson, M. I., Lamph, W. W., Heyman,R. A., Teng, M., Chandraratna, R. A. S., Shudo, K., Hong, W. K., and Lotan, R.Differential effects of synthetic nuclear retinoid receptor-selective retinoids on thegrowth of human non-small cell lung carcinoma cells. Cancer Res., 57: 4931–4939,1997.16. Thornberry, N. A., and Lazebnik, Y. Caspases. Enemies within. Science (Wash. DC),281: 1312–1316, 1998.17. Hengartner, M. O. The biochemistry of apoptosis. Nature (Lond.), 407: 770–776,2000.

8. Adachi, H., Preston, G., Harvat, B., Dawson, M. I., and Jetten, A. Inhibition of cellproliferation and induction of apoptosis by the retinoid AHPN in human lungcarcinoma cells. Am. J. Respir. Cell Mol., 18: 823–333, 1998.9. Li, Y., Lin, B., Agadir, A., Liu, R., Dawson, M. I., Reed, J. C., Fontana, J. A., Bost,F., Hobbs, P. D., Zheng, Y., Chen, G-Q., Shroot, B., Mercola, D., and Zhang, X-K.Molecular determination of AHPN (CD437)-induced growth arrest and apoptosis inhuman lung cancer cell lines. Mol. Cell. Biol., 18: 4719–4731, 1998.10. Sun, S-Y., Yue, P., Shroot, B., Hong, W. K., and Lotan, R. Induction of apoptosis inhuman non-small cell lung carcinoma cells by a novel synthetic retinoid CD437.J. Cell. Physiol., 173: 279–284, 1997.11. Bernard, B. A., Bernardon, J-M., Delescluse, C., Martin, B., Lenoir, M-C., Margnan,J., Charpentier, B., Pilgrim, W. R., Reichert, U., and Shroot, B. Identification ofsynthetic retinoids with selectivity for human nuclear retinoic acid receptor .Biochem. Biophys. Res. Commun., 186: 977–983, 1992.12. Sun, S-Y., Yue, P., Wu, G. S., El-Deiry, W. S., Shroot, B., Hong, W. K., and Lotan,R. Mechanisms of apoptosis induced by the synthetic retinoid CD437 in humannon-small cell lung carcinoma cells. Oncogene, 18: 2357–2365, 1999.13. Sun, S-Y., Yue, P., Wu, G. S., El-Deiry, W. S., Shroot, B., Hong, W. K., and Lotan,R. Implication of p53 in growth arrest and apoptosis induced by the synthetic retinoidCD437 in human lung cancer cells. Cancer Rec., 59: 2829–2833, 1999.14. Sun, S. Y., Yue, P., Hong, W. K., and Lotan, R. Induction of Fas expression andaugmentation of Fas/Fas ligand-mediated apoptosis by the synthetic retinoid CD437in human lung cancer cells. Cancer Res., 60: 6537–6543, 2000.15. Sun, S-Y., Yue, P., Shroot, B., Michel, S., Dawson, M. I., Lamph, W. W., Heyman,R. A., Teng, M., Chandraratna, R. A. S., Shudo, K., Hong, W. K., and Lotan, R.Differential effects of synthetic nuclear retinoid receptor-selective retinoids on thegrowth of human non-small cell lung carcinoma cells. Cancer Res., 57: 4931–4939,1997.16. Thornberry, N. A., and Lazebnik, Y. Caspases. Enemies within. Science (Wash. DC),281: 1312–1316, 1998.17. Hengartner, M. O. The biochemistry of apoptosis. Nature (Lond.), 407: 770–776,2000.