The p16INK4a tumor suppressor controls p21WAF1 induction in response to ultraviolet light

Al-Mohanna, Mai; Al‐Khalaf, Huda H.; Al‐Yousef, Nujoud; Aboussekhra, Abdelilah

doi:10.1093/nar/gkl1075

Cited by 69 publications

(67 citation statements)

References 48 publications

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“…This has been done as previously described (16). Antibodies directed against p53 (DO-I), p21 (187), survivin (C-19), glyceraldehyde-3-phosphate dehydrogenase (GAPDH; FL-335), proliferating cell nuclear antigen (PCNA; PC-10), and h-actin (C-11) were purchased from Santa Cruz.…”

Section: Methodsmentioning

confidence: 99%

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Breast Carcinoma–Associated Fibroblasts and Their Counterparts Display Neoplastic-Specific Changes

Hawsawi¹,

Ghebeh²,

Hendrayani³

et al. 2008

Cancer Research

128

104

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It has become clear that the initiation and progression of carcinomas depend not only on alterations in epithelial cells, but also on changes in their microenvironment. To identify these changes, we have undertaken cellular and molecular characterization of carcinoma-associated fibroblasts (CAF) and their tumor counterpart fibroblasts (TCF) isolated from 12 breast cancer patients. Normal breast fibroblasts (NBF) from plastic surgery were used as normal control. We present evidence that both CAFs and TCFs are myofibroblasts and show tumorassociated features. Indeed, the p53/p21 response pathway to ;-rays was defective in 70% CAFs, whereas it was normal in all the TCF and NBF cells. In addition, the basal levels of the p53 and p21 proteins were significantly low in 83% of CAFs and modulated in the majority of TCFs compared with NBFs. Interestingly, both TCFs and CAFs expressed high levels of the cancer marker survivin and consequently exhibited high resistance to cisplatin and UV light. Moreover, most CAFs were positive for the proliferation marker Ki-67 and exhibited high proliferation rate compared with NBFs and TCFs. However, proliferating cell nuclear antigen was highly expressed in both CAFs and TCFs. Using the two-dimensional gel electrophoresis technique, we have also shown that CAF, TCF, and NBF cells present different proteome profiles, with many proteins differentially expressed between these cells. Taken together these results indicate that different genetic alterations can occur in breast CAFs and their corresponding adjacent counterparts, showing the important role that stroma could play in breast carcinogenesis and treatment. [Cancer Res 2008;68(8):2717-25]

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Section: Methodsmentioning

confidence: 99%

“…The expression levels of the immunoblotted proteins were measured using the densitometer (BIO-RAD GS-800 Calibrated Densitometer) as previously described (16).…”

Section: Methodsmentioning

confidence: 99%

Breast Carcinoma–Associated Fibroblasts and Their Counterparts Display Neoplastic-Specific Changes

Hawsawi¹,

Ghebeh²,

Hendrayani³

et al. 2008

Cancer Research

128

104

View full text Add to dashboard Cite

show abstract

“…Immunoblotting SDS-PAGE was conducted using 12% separating minigels as previously described (14). The antibodies directed against p53 (DO-I), PCNA (PC-10), Ubiquitin (P4D1), Atr (N-19), a-tubulin (B-5-1-2), and b-actin (C-11) were purchased from Santa Cruz (USA); the specific p16 Phospho-Ser7, 8, 140 and 152 antibodies were purchased from ABGENT; p16 from BD Biosciences, pPRB Ser-612 (4E4) from ABNOVA, pPRB Ser-780 (9307), p27 and Skp2 from Cell Signaling.…”

Section: Cellular Lysate Preparationmentioning

confidence: 99%

“…Stable transfection was carried out using human dermal fibroblast Nucleofector Kit (Amaxa Biosystems) following the protocol recommended by the manufacturer as previously described (14).…”

Section: Analysis Of Protein Half-lifementioning

confidence: 99%

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The Atr Protein Kinase Controls UV-Dependent Upregulation of p16INK4A Through Inhibition of Skp2-Related Polyubiquitination/Degradation

Al‐Khalaf¹,

Hendrayani²,

Aboussekhra³

2011

Molecular Cancer Research

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The tumor suppressor p16 INK4A , a phosphoprotein that exists in human cells under both phosphorylated and nonphosphorylated forms, plays crucial roles during the cellular response to UV light. However, it is still unclear how this protein is activated in response to this carcinogenic agent. We have shown here that UVC upregulates p16 INK4A and the phosphorylated form of the protein at the 4 serine sites; . This accumulation of p16 INK4A occurred through increasing the stability of both forms of the protein. Importantly, phospho-p16 INK4A showed much higher stability, and UV treatment strongly increased its level in absence of de novo protein synthesis. Furthermore, we have shown that the UV-dependent upregulation of both forms of p16 INK4A is under the control of the protein kinase Atr, which suppresses their UVC-dependent proteasomal degradation. Interestingly, although this degradation is ubiquitin-related for p16 INK4A through the Skp2 ubiquitin ligase protein, it is ubiquitin-independent for the phosphorylated form. In addition, we present clear evidence that Skp2 is upregulated in ATR-deficient cells, leading to the downregulation of the p27 Kip1 protein in response to UVC light. Moreover, we have shown a preferential association of endogeneous phospho-p16 INK4A with Cdk4. This association increased following UV-treatment mainly for p16 INK4A phosphorylated at Ser-140 and Ser-152. Besides, we have shown that Atr regulates UV-related p16/Cdk4-dependent and -independent phosphorylation of pRB and G1 cell cycle delay. Together, these results indicate that p16 INK4A and p27 Kip1 are key targets in the Atr-dependent signaling pathway in response to UV damage.

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Enhancement of p53 expression in keratinocytes by the bioflavonoid apigenin is associated with RNA‐binding protein HuR

Tong¹,

Pelling²

2008

Molecular Carcinogenesis

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We have reported previously that apigenin, a naturally occurring non-mutagenic flavonoid, increased wild type p53 protein expression in the mouse keratinocyte 308 cell line by a mechanism involving p53 protein stabilization. Here we further demonstrated that the increase in p53 protein level induced by apigenin treatment of 308 keratinoyctes was not the result of enhanced transcription, mRNA stabilization or cytoplasmic export of p53 mRNA. Instead, biosynthetic labeling showed that apigenin increased nascent p53 protein synthesis by enhancing p53 translation. The AU-rich element (ARE) within the 3′-untranslated region (UTR) of p53 mRNA was found to be responsible for apigenin’s ability to increase p53 translation, as demonstrated in studies wherein the 3′-UTR of p53 mRNA containing the ARE was fused downstream of a luciferase reporter gene. Furthermore, apigenin treatment increased the level of association of the RNA binding protein HuR with endogenous p53 mRNA. Apigenin treatment also augmented HuR translocation into the cytoplasm. Overexpression of HuR enhanced apigenin-induced p53 protein expression in 308 keratinocytes, whereas siRNA-mediated HuR reduction suppressed apigenin-induced p53 protein expression and de novo translation of p53. Moreover, apigenin treatment of cells induced p16 protein expression, which in turn was correlated with cytoplasmic localization of HuR induced by apigenin. Overall, these findings indicate that, in addition to modulating p53 protein stability, one of the mechanisms by which apigenin induces p53 protein expression is enhancement of translation through the RNA binding protein HuR.

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The p16INK4a tumor suppressor controls p21WAF1 induction in response to ultraviolet light

Cited by 69 publications

References 48 publications

Breast Carcinoma–Associated Fibroblasts and Their Counterparts Display Neoplastic-Specific Changes

Breast Carcinoma–Associated Fibroblasts and Their Counterparts Display Neoplastic-Specific Changes

The Atr Protein Kinase Controls UV-Dependent Upregulation of p16INK4A Through Inhibition of Skp2-Related Polyubiquitination/Degradation

Enhancement of p53 expression in keratinocytes by the bioflavonoid apigenin is associated with RNA‐binding protein HuR

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