Egyptian Journal of Pathology:
Expression of cell-cycle regulators p53, p27, and p21 in mucoepidermoid and adenoid cystic carcinomas of the minor salivary glands
Talaat, Iman M.
Department of Pathology, Faculty of Medicine, University of Alexandria, Alexandria, Egypt
Correspondence to Iman M. Talaat, PhD, Department of Pathology, Faculty of Medicine, University of Alexandria, 21411 Alexandria, Egypt Tel: +201221037274; fax: +20 3 596 0720; e-mail: firstname.lastname@example.org
Received March 25, 2013
Accepted April 15, 2013
Background: The orderly progression of cells through different phases of the cell cycle is orchestrated by various molecules and proteins. p53 plays a crucial role in stress response and tumor suppression. It is a unique cellular processor that integrates signals from various pathways in order to coordinate cell proliferation, differentiation, and apoptosis. p21WAF1/CIP1 and p27 have key positions in cell-cycle regulations, leading to arrest of cell proliferation. They enable a repair process of DNA damage. In several human tumors, a loss of these proteins is associated with poor clinical outcome. Despite recent progress in molecular medicine, there is still a paucity of data on the involvement of cell-cycle regulatory proteins in the pathogenesis of salivary gland tumors.
Aim: The present work was performed to assess the immunohistochemical expression of p53, p27, and p21 in 15 patients with mucoepidermoid carcinomas (MECs) and adenoid cystic carcinomas (ACCs) of the minor salivary glands and their possible correlation with histopathologic grading.
Results: The present study included eight patients with ACC and seven patients with MEC. Most of the ACC patients (62.5%) showed positive reaction for p53, whereas only 25% were immunoreactive to p21. Among the seven examined MEC patients, the overall expression of p53 was detected only in those with high-grade tumors. With respect to p21, a moderate reaction was detected in a patient with low-grade MEC. In contrast, immunoreactivity to the p27 protein was detected only in low-grade tumors.
Conclusion: The cell-cycle regulatory protein p53 was highly expressed in high-grade neoplasms, whereas the reverse was noticed in the case of p27. These findings have a strong prognostic impact. p21 overexpression may be a useful prognostic marker when evaluated in conjunction with p53 status.
Salivary gland tumors are relatively uncommon, comprising no more than 1% of all tumors and 3% of all head and neck neoplasias (Russo et al., 2005). Their morphologic diversity and relative rarity frequently pose a challenge in their diagnosis and treatment (Papadogeorgakis et al., 2011). As the clinical course and final outcome of many patients with salivary gland tumors cannot be reliably predicted on the basis of histomorphologic features, it is highly desirable to find new prognostic markers aimed at better characterizing tumor aggressiveness (Nagler et al., 2003).
Mucoepidermoid carcinoma (MEC), representing 5% of all salivary gland tumors and 20% of the malignant forms, is the most frequently occurring primary malignancy of the salivary gland in both adults and children. This tumor is characterized by squamoid cells, mucus-producing cells, and cells of intermediate type, with a marked variation in prognosis (Miyabe et al., 2009).
Adenoid cystic carcinoma (ACC) is a malignant salivary gland tumor characterized by a slow but relentless progression plagued by local recurrences, late metastases, and ultimately fatal outcome (Khafif et al., 2005). Histologically, ACC is a biphasic tumor comprising ductal and myoepithelial components. The three major growth patterns are tubular, cribriform, and solid. These growth patterns form the basis for histologic grading, and the quantity of the solid component is considered to be the most significant adverse prognosticator (Da Cruz Perez et al., 2006). However, it is often difficult to predict the prognosis of ACC by histologic findings alone; thus, there is a need to explore additional parameters for predicting the prognosis (Ciccolallo et al., 2009).
Despite recent progress in molecular medicine, there is still a paucity of data on the involvement of cell-cycle regulatory proteins in the pathogenesis of head and neck tumors, particularly of salivary glands (Kelsch et al., 1997; Russo et al., 2005).
Cell proliferation control is ensured by a group of proteins named cyclin-dependent kinases (CDKs), the activation of which is dependent on phosphorylation and cyclin association. In parallel, these CDKs are negatively controlled by two distinct groups of inhibitory proteins, the cyclin-dependent kinase inhibitors (CDKIs) (Affolter et al., 2005; Hernández-Zavala et al., 2005). CDKIs fall into two families, INK4 and CIP/KIP, on the basis of their structural and functional properties (Hirai et al., 1995; Choi et al., 2001; Chung et al., 2008).
The CIP/KIP family of genes includes p21Waf1, p27Kip1, and p57Kip2. They possess structural similarity – that is, a 60-residue protein homology, which is very important for their inhibitory activities. These proteins are potent inhibitors of a wide range of cyclin–CDK complexes implicated in G1 and S phase and are said to be universal CKIs (Chung et al., 2008; Croucher et al., 2010).
Progression through the cell cycle is regulated by a variety of proteins that play an important role in allowing the correct order and timing of events involved in chromosomal repair, duplication, and separation (Kapuy et al., 2009). CDKs and their regulatory partners, cyclins, form heterodimeric protein complexes; they appear and degrade during predetermined steps in the cell cycle (Schoelch et al., 1999). These proteins allow for orderly progression of the cell cycle and also act to phosphorylate fundamental cell cycle proteins (Martinsson-Ahlzén et al., 2008).
The p53 gene is a tumor suppressor gene that acts as the ‘guardian of the genome’. Many diverse cellular events, including DNA damage and hypoxia, activate the p53 gene. The p53 protein functions as a transcription factor, regulating downstream genes involved in cell-cycle arrest, DNA repair, and programmed cell death (Ryan, 2011). Loss of p53 function confers genomic instability, impaired apoptosis, and diminished cell-cycle restraint. Therefore, p53 mutations are responsible for certain critical features of malignancy. Alteration of p53 is the most common mutation in human cancer (Shi et al., 2010). Loss of p53 function has been demonstrated in about one half of all human cancers, including malignant salivary gland tumors (Affolter et al., 2005).
The p21 protein is the gene product of the WAF1/CIP1 gene, which plays an important role in regulating the G1–S transition of the cell cycle (Chung et al., 2008). In response to DNA damage, wild-type p53 accumulates and binds to the promoter region of the p21WAF1/CIP1 gene. This induces the expression of p21WAF1/CIP1, which inhibits the activity of the cyclin/CDK complex to block cell-cycle progression. The levels of p21WAF1/CIP1 may also be elevated by nondependent mechanisms (Huo et al., 2004). Further, p21WAF1/CIP1 is associated with terminal differentiation and cell senescence, and thus may play a role in cell maturation and cell death (Schwandner et al., 2002).
p27 is a member of the universal CKDI family (Dai et al., 2013). p27 blocks the cell cycle at the G1/S phase checkpoint and is highly expressed in cells arrested at G0 and G1 phases. Enhanced p27 expression is induced by cell–cell contact and by specific growth factors such as transforming growth factor-β and cyclic AMP (Miskimins et al., 2001). The prognostic value of p27 expression has been reported in various human tumors (Lloyd et al., 1999; Seki et al., 2009) The low p27 expression was associated with an unfavorable prognosis for squamous cell carcinoma of the tongue. It was found that p27 can play a pathogenic role in the malignant transformation of tumors of salivary gland origin (Ben-Izhak et al., 2009).
This work aimed to assess the immunohistochemical expression of p53, p27, and p21 in minor salivary gland MEC and ACC and their possible correlation with histopathologic grading.
Materials and methods
Fifteen cases of ACC and MEC were selected from the archival files of the Pathology and Oral Pathology Departments, Faculties of Medicine and Dentistry, Alexandria University, Egypt, between 2005 and 2010.
Serial sections of 4-μm thickness were cut from each paraffin-embedded tissue block. Sections were stained with hematoxylin and eosin for confirmation of the histopathological diagnosis and for application of immunohistochemical (IHC) assays.
Antibodies and immunohistochemical assays
IHC study was performed to detect the expression of p53, p21, and p27 using monoclonal anti-p53 (Clone DO7; Dako, Glostrup, Denmark), p21 (Clone IB4; Novocastra, New Castle, UK), and p27 (Clone D10; Novocastra) antibodies. Sections were deparaffinized and dehydrated. Microwave unmasking of antigens was performed for 20 min in 0.01 mol/l citrate buffer at 98°C (pH 6). The sections were then left to cool for 1 h. Endogenous peroxide was subsequently blocked with 3% hydrogen peroxide for 10 min, followed by washing for 5 min with PBS. The specimens were incubated overnight at 4°C with anti-p53, p21, and p27 antibodies diluted at 1 : 100, 1 : 40, 1 : 40, respectively. They were then washed three times in PBS for 5 min each and incubated for 30 min with labeled-polymer-conjugated secondary antibody (Envision Kit; Dako, Carpinteria, California, USA). Finally, they were washed and developed with 3,3-diaminobenzidinetetrahydrochloride for 5 min, lightly counterstained with hematoxylin, dehydrated, and mounted.
Tumor cells that showed positive nuclear reaction were semiquantitatively evaluated in at least 1000 cells, which were examined at ×40 magnification, and the number of positive tumor cells from the total number of neoplastic cells present in the same area was recorded. The biomarker immunoreactivity was classified as reported in the studies by Aoki et al. (2004) and Croucher et al. (2010) as follows:
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Fisher’s exact test was used to evaluate the association between the cell cycle proteins and the two studied tumors, namely, MEC and ACC. Correlation between tumor grade and IHC results was determined using the Spearman correlation rank test. Data analysis was carried out using the SPSS statistical package, release 5.0.1 (SPSS Inc., Chicago, Illinois, USA). Results were considered statistically significant when the P value was less than 0.05.
In the present work, 15 malignant salivary gland tumors were analyzed immunohistochemically for the expression of the cell-cycle regulators p53, p21, and p27.
The present work included eight patients with ACC of different patterns and seven patients with MEC.
Of the eight cases of ACC, four were predominantly cribriform (Fig. 1a), three were tubular-trabecular (Fig. 1b), and one was of solid type (Fig. 1c). Among the patients with MEC, four had low-grade tumors (Fig. 1d) and three had high-grade tumors (Fig. 1e).
Among the examined malignant salivary gland tumors, 53.33% (8/15) showed positive reaction for p53, whereas 40% (6/15) were p27 positive. However, p21 was detected in only 20% (3/15) of tumors (Table 1).
With regard to the ACC patients, 62.5% showed positive immune signals for the p53 protein and 25% were immunoreactive for p21. Intense nuclear brownish reaction for p53 was detected in the cribriform (Fig. 2a) and solid patterns, whereas a moderate to weak reaction was noted in the tubular pattern. p21 was detected only in the cribriform and tubular patterns of ACC. The reaction was moderate (Fig. 2b).
Among the seven examined MEC patients, the expression of p53 was detected only in high-grade tumors. Intense nuclear reaction was observed in the anaplastic epidermoid cells in two patients (Fig. 3a), whereas moderate reaction was detected in one case. With regard to p21, a moderate reaction was detected in only one patient with low-grade MEC (Fig. 3b). Interestingly, the high-grade MECs were completely negative for p21 protein.
In this work, p27 protein was detected only in low-grade tumors, whereas it was completely negative in high-grade ones. In case of ACC, the immunoreaction was expressed mainly in the tubular-trabecular pattern. Only one patient with cribriform pattern showed weak reaction (Fig. 4a). In case of MEC, the p27 protein was detected only in low-grade tumors (Fig. 4b). However, it was completely negative in the high-grade ones.
No statistically significant difference was detected between ACC and MEC with respect to their IHC results for any of the studied cell-cycle proteins (P=0.57, 1.0, 0.44, respectively) (Table 2).
Tumor grade is positively correlated only with p53 expression; there is no correlation with either p21 or p27 (Table 3).
The significance of CIP/KIP protein expression in malignant neoplasms of the salivary glands is still unclear. The few reports in literature are contradictory (Affolter et al., 2005).
p53 is a tumor suppressor gene located on the short arm of chromosome 17, whose protein product acts as a nuclear transcription factor with various functions, including the arrest of cell-cycle progression. (Das et al., 2008). Mutation of this gene inactivates this tumor suppressor activity and is related to tumor progression and survival (Fisher, 2001). There are conflicting results on p53 as a prognostic marker in head and neck malignancies, and the role of p53 mutations in the development and progression of salivary gland neoplasms remains largely unknown (Nagler et al., 2003). According to the literature, involvement of the p53 mutation seems to play an important role in salivary gland malignancies in general at later rather than earlier stages of tumor progression and recurrence (Nagao et al., 1998; Kiyoshima et al., 2001; Mutoh et al., 2001).
Our results revealed that 62.5% of ACCs exhibited immunopositivity for the tumor suppressor p53 with different grades of intensities. This is in agreement with the results of Röijer et al. (1997) and Al-Rawi et al. (2010), who reported moderate p53 staining in their studied cases of ACC and correlated the associated immunoreactivity to the large size of the tumor, high grade, and extent of invasion. The same observation was suggested by Kiyoshima et al. (2001) and Da Cruz Perez et al. (2004). Many other authors found that p53 analysis may be a useful prognostic indicator of aggressive disease (Zhu et al., 1997; Chau et al., 2001; and Wegner et al., 2007).
p53 immunopositivity in MEC varies greatly from 8 to 87% (Kiyoshima et al., 2001; Abd-Elhamid and Elmalahy, 2010). In the present study, 42.9% of MEC cases revealed p53 expression. The immunopositivity was mainly detected in high-grade tumors. This is in agreement with the results of Yin et al. (2000). They stated that grade II and grade III MECs had a slightly higher rate of p53 immunopositivity compared with grade I MECs. They suggested that p53 is an inefficient prognostic marker as their patients with p53-negative tumors showed better survival.
The CDKI p21/waf1 is regulated by p53-dependent and p53-independent pathways (Ng et al., 1999). The degree of p21 immunoreactivity is assumed to reflect the degree of expression of the normal p21 gene and serves as a useful tool for assessing its function (Goan et al., 2005). p21 expression appears to vary in different human malignancies (Huang and Tao, 2000). Its expression has been reported to be increased in cutaneous squamous cell carcinoma (Stoyanova et al., 2012), non-small-cell lung carcinoma (Groeger et al., 2000), head and neck cancer (Kapranos et al., 2001), and hepatocellular carcinoma (Zhang et al., 2009) but decreased in colorectal carcinoma (Al-Maghrabi et al., 2012) and ovarian carcinoma (Yan et al., 2004).
In the present study, 80% of the examined malignant salivary gland tumors showed negative reaction to p21. Only 25% of ACCs were positive. This is commensurate with the results of Affolter et al. (2005). Seventy-two percent of their studied patients were p21 negative on IHC.
In the present work, only one of the studied MEC samples was immunopositive for p21; it was a low-grade one. In contrast, Etemad-Moghadam et al. (2007) detected p21 in 22.5% of their examined MEC specimens, with low expression in all grades. They claim that the loss of p21 develops in the earlier stages of tumorigenesis but not in later stages.
p27 regulates progression from G1 to S phase of the cell cycle by inhibiting cyclin-D or E-dependent kinase activity (Boudová et al., 2003). Several clinical reports have shown that low p27 expression is associated with poor prognosis in patients with breast cancer (Filipits et al., 2009), colon cancer (Dai et al., 2003), gastric cancer (Takano et al., 2000), and oral cancer (Kudo et al., 2000).
Our results revealed that p27 expression was detected in low-grade malignant salivary gland tumors. Choi et al. (2001) reported that low p27 was seen more often in high-grade MECs than in low-grade ones. They stated that the loss of p27 expression was related to the loss of its inhibitory role in cell-cycle progression, as well to rapid tumor growth and high frequency of metastasis. Moreover, Keikhaee et al. (2007) and Affolter et al. (2005) showed that downregulation of p27 was observed in ACC and was well correlated to metastasis.
This study illustrated that cell-cycle regulatory proteins are dysregulated during the development of salivary gland cancer. p53 was highly expressed in high-grade neoplasms and thus has a strong prognostic impact. p21 was detected only in a few patients and may be a useful prognostic marker when evaluated in conjunction with p53 status. However, p27 was associated with loss of expression in high-grade tumors and was expressed only in low-grade ones. It could be a possible parameter for poor prognosis in malignant salivary gland tumors.
Conflicts of interest
There are no conflicts of interest.
Abd-Elhamid ES, Elmalahy MH.Image cytometric analysis of p53 and mdm-2 expression in primary and recurrent mucoepidermoid carcinoma of parotid gland: immunohistochemical study.Diagn Pathol2010;5:72–84.
Affolter A, Helmbrecht S, Finger S, Hörmann K, Götte K.Altered expression of cell cycle regulators p21, p27, and p53 in tumors of salivary glands and paranasal sinuses.Oncol Rep2005;13:1089–1094.
Aoki T, Tsukinoki K, Karakida K, Ota Y, Otsuru M, Kaneko A.Expression of cyclooxygenase-2, Bcl-2 and Ki-67 in pleomorphic adenoma with special reference to tumor proliferation and apoptosis.Oral Oncol2004;40:954–959.
Al-Maghrabi J, Al-Ahwal M, Buhmeida A, Syrjänen K, Sibyani A, Emam E, et al..Expression of cell cycle regulators P21 and P27 as predictors of disease outcome in colorectal carcinoma.J Gastrointest Cancer2012;43:279–287.
Al-Rawi NH, Omer H, Al Kawas S.Immunohistochemical analysis of P53 and bcl-2 in benign and malignant salivary glands tumors.J Oral Pathol Med2010;39:48–55.
Ben-Izhak O, Akrish S, Gan S, Nagler RM.p27 and salivary cancer.Cancer Immunol Immunother2009;58:469–473.
Boudová L, Vaněcek T, Síma R, Bouda J, Hes O, Fakan F.Role of p27Kip1 protein in the cell cycle and its appearance in lymphoid tissues, particularly non-Hodgkin’s B-cell lymphomas. Review (in Czech).Cesk Patol2003;39:126–129.
Chau Y-P, Hongyo T, Aozasa K, Chan JKC.Dedifferentiation of adenoid cystic carcinoma: report of a case implicating p53 gene mutation.Hum Pathol2001;32:1403–1407.
Choi CS, Choi G, Jung KY, Choi JO, Chae YS.Low expression of p27Kip1 in advanced mucoepidermoid carcinomas of head and neck.Head Neck2001;23:292–297.
Chung C-J, Huang C-J, Pu Y-S, Su C-T, Huang Y-K, Chen Y-T, Hsueh Y-M.Polymorphisms in cell cycle regulatory genes, urinary arsenic profile and urothelial carcinoma.Toxicol Appl Pharmacol2008;232:203–209.
Ciccolallo L, Licitra L, Cantú G, Gatta G.Survival from salivary glands adenoid cystic carcinoma in European populations.Oral Oncol2009;45:669–674.
Croucher DR, Rickwood D, Tactacan CM, Musgrove EA, Daly RJ.Cortactin modulates RhoA activation and expression of Cip/Kip cyclin-dependent kinase inhibitors to promote cell cycle progression in 11q13-amplified head and neck squamous cell carcinoma cells.Mol Cell Biol2010;30:5057–5070.
Da Cruz Perez DE, Pires FR, Alves FA, Almeida OP, Kowalski LP.Salivary gland tumors in children and adolescents: a clinicopathologic and immunohistochemical study of fifty-three cases.Int J Pediatr Otorhinolaryngol2004;68:895–902.
Da Cruz Perez DE, De Abreu Alves F, Nobuko Nishimoto I, De Almeida OP, Kowalski LP.Prognostic factors in head and neck adenoid cystic carcinoma.Oral Oncol2006;42:139–146.
Dai JY, Liang XP, Wen JL, Li CY, Deng CZ, Zhang ZH.Expression of P27 protein and cyclin E in colon cancer.Ai Zheng2003;22:1093–1095.
Dai L, Liu Y, Liu J, Wen X, Xu Z, Wang Z, et al..A novel cyclinE/cyclinA-CDK inhibitor targets p27Kip1 degradation, cell cycle progression and cell survival: implications in cancer therapy.Cancer Lett2013;333:103–112.
Das S, Boswell SA, Aaronson SA, Lee SW.p53 promoter selection: choosing between life and death.Cell Cycle2008;7:154–157.
Etemad-Moghadam S, Baghaee F, Tirgary F, Motahhary P, Khalili M, Eshghyar N, et al..Expression of p21WAF in salivary gland mucoepidermoid carcinoma and its relation to histologic grade.Int J Surg Pathol2007;15:6–13.
Filipits M, Rudas M, Heinzl H, Jakesz R, Kubista E, Lax S, et al..Low p27 expression predicts early relapse and death in postmenopausal hormone receptor-positive breast cancer patients receiving adjuvant tamoxifen therapy.Clin Cancer Res2009;15:5888–5894.
Fisher DE.The p53 tumor suppressor: critical regulator of life & death in cancer.Apoptosis2001;61–27–15.
Goan Y-G, Hsu H-K, Chang H-C, Chou Y-P, Chiang K-H, Cheng J-T.Deregulated p21WAF1 overexpression impacts survival of surgically resected esophageal squamous cell carcinoma patients.Ann Thorac Surg2005;80:1007–1016.
Groeger AM, Caputi M, Esposito V, Baldi A, Rossiello R, Santini D, et al..Expression of p21 in non small cell lung cancer relationship with PCNA.Anticancer Res2000;20:3301–3306.
Hernández-Zavala A, Córdova E, Del Razo LM, Cebrián ME, Garrido E.Effects of arsenite on cell cycle progression in a human bladder cancer cell line.Toxicology2005;207:49–57.
Hirai H, Roussel MF, Kato J-Y, Ashmun RA, Sherr CJ.Novel INK4 proteins, p19 and p18, are specific inhibitors of the cyclin D-dependent kinases CDK4 and CDK6.Mol Cell Biol1995;15:2672–2681.
Huang Q, Tao Y.Detection of point mutations in promoter and coding sequence of p21 gene in a variety of human malignancies.Chinese J Med Genet2000;17:169–172.
Huo JX, Metz SA, Li GD.p53-independent induction of p21waf1/cip1 contributes to the activation of caspases in GTP-depletion-induced apoptosis of insulin-secreting cells.Cell Death Differ2004;11:99–109.
Kapranos N, Stathopoulos GP, Manolopoulos L, Kokka E, Papadimitriou C, Bibas A, et al..p53, p21 and p27 protein expression in head and neck cancer and their prognostic value.Anticancer Res2001;211B521–528.
Kapuy O, He E, López-Avilés S, Uhlmann F, Tyson JJ, Novák B.System-level feedbacks control cell cycle progression.FEBS Lett2009;583:3992–3998.
Keikhaee MR, Kudo Y, Siriwardena S, Wu L, Ogawa I, Takata T.Skp2 expression is associated with down-regulation of p27 protein and cell proliferation in salivary adenoid cystic carcinoma.Virchows Arch2007;450:567–574.
Kelsch RD, Bhuiya T, Fuchs A, Gentile P, Kahn MA, Fantasia JE.Polymorphous low-grade adenocarcinoma: flow cytometric, p53, and PCNA analysis.Oral Surg Oral Med Oral Pathol Oral Radiol Endod1997;84:391–399.
Khafif A, Anavi Y, Haviv J, Fienmesser R, Calderon S, Marshak G.Adenoid cystic carcinoma of the salivary glands: a 20-year review with long-term follow-up.Ear, Nose Throat J2005;84:662–667.
Kiyoshima T, Shima K, Kobayashi I, Matsuo K, Okamura K, Komatsu S, et al..Expression of p53 tumor suppressor gene in adenoid cystic and mucoepidermoid carcinomas of the salivary glands.Oral Oncol2001;37:315–322.
Kudo Y, Takata T, Ogawa I, Zhao M, Sato S, Takekoshi T, et al..Reduced expression of p27(Kip1) correlates with an early stage of cancer invasion in oral squamous cell carcinoma.Cancer Lett2000;151:217–222.
Lloyd RV, Erickson LA, Jin L, Kulig E, Qian X, Cheville JC, Scheithauer BW.p27(kip1): a multifunctional cyclin-dependent kinase inhibitor with prognostic significance in human cancers.Am J Pathol1999;154:313–323.
Martinsson-Ahlzén H-S, Liberal V, Grünenfelder B, Chaves SR, Spruck CH, Reed SI.Cyclin-dependent kinase-associated proteins Cks1 and Cks2 are essential during early embryogenesis and for cell cycle progression in somatic cells.Mol Cell Biol2008;28:5698–5709.
Miskimins WK, Wang G, Hawkinson M, Miskimins R.Control of cyclin-dependent kinase inhibitor p27 expression by cap-independent translation.Mol Cell Biol2001;21:4960–4967.
Miyabe S, Okabe M, Nagatsuka H, Hasegawa Y, Inagaki A, Ijichi K, et al..Prognostic significance of p27Kip1, Ki-67, and CRTC1-MAML2 fusion transcript in mucoepidermoid carcinoma: a molecular and clinicopathologic study of 101 cases.J Oral Maxillofac Surg2009;67:1432–1441.
Mutoh H, Nagata H, Ohno K, Numata T, Nagao T, Nagao K, Konno A.Analysis of the p53 gene in parotid gland cancers: a relatively high frequency of mutations in low-grade mucoepidermoid carcinomas.Int J Oncol2001;18:781–786.
Nagao T, Sugano I, Ishida Y, Hasegawa M, Matsuzaki O, Konno A, et al..Basal cell adenocarcinoma of the salivary glands: comparison with basal cell adenoma through assessment of cell proliferation, apoptosis, and expression of p53 and bcl-2.Cancer1998;82:439–447.
Nagler RM, Kerner H, Ben-Eliezer S, Minkov I, Ben-Itzhak O.Prognostic role of apoptotic, Bcl-2, c-erbB-2 and p53 tumor markers in salivary gland malignancies.Oncology2003;64:389–398.
Ng IOL, Lam KY, Ng M, Regezi JA.Expression of p21/waf1 in oral squamous cell carcinomas – correlation with p53 and mdm2 and cellular proliferation index.Oral Oncol1999;35:63–69.
Papadogeorgakis N, Parara E, Petsinis V, Pappa E, Nikolaidis A, Alexandridis K.A retrospective review of malignant minor salivary gland tumors and a proposed protocol for future care.Craniomaxillofac Trauma Reconstr2011;4:1–10.
Russo G, Zamparelli A, Howard CM, Minimo C, Bellan C, Carillo G, et al..Expression of cell cycle-regulated proteins pRB2/p130, p107, E2F4, p27, and pCNA in salivary gland tumors: prognostic and diagnostic implications.Clin Cancer Res2005;11:3265–3273.
Röijer E, Dahlenfors R, Mark J, Stenman G.Observations by chromosome banding, FISH and immunohistochemistry in an adenoid cystic carcinoma with del(17)(p13) as the sole deviation.Virchows Arch1997;430:339–342.
Ryan KM.P53 and autophagy in cancer: guardian of the genome meets guardian of the proteome.Eur J Cancer2011;47:44–50.
Schoelch ML, Regezi JA, Dekker NP, Ng IOL, McMillan A, Ziober BL, et al..Cell cycle proteins and the development of oral squamous cell carcinoma.Oral Oncol1999;35:333–342.
Schwandner O, Bruch H-P, Broll R.Prognostic significance of p21 and p27 protein, apoptosis, clinical and histologic factors in rectal cancer without lymph node metastases.Eur Surg Res2002;34:389–396.
Seki R, Ohshima K, Fujisaki T, Uike N, Kawano F, Gondo H, et al..Prognostic significance of S-phase kinase-associated protein 2 and p27kip1 in patients with diffuse large B-cell lymphoma: effects of rituximab.Ann Oncol2009;21:833–841.
Shi M, Liu D, Shen B, Guo N.Helpers of the cellular gatekeeper-miRNAs dance in P53 network.Biochim Biophys Acta2010;1805:218–225.
Stoyanova T, Roy N, Bhattacharjee S, Kopanja D, Valli T, Bagchi S, Raychaudhuri P.p21 cooperates with DDB2 protein in suppression of ultraviolet ray-induced skin malignancies.J Biol Chem2012;287:3019–3028.
Takano Y, Kato Y, Van Diest PJ, Masuda M, Mitomi H, Okayasu I.Cyclin D2 overexpression and lack of p27 correlate positively and cyclin E inversely with a poor prognosis in gastric cancer cases.Am J Pathol2000;156:585–594.
Wegner A, Waśniewska E, Jarmołowska-Jurczyszyn D, Golusiński W, Biczysko W.The role of immunohistochemical staining (protein p53, cyklin D1) in the prognosis of adenoid cystic carcinoma salivary gland tumors.Otolaryngol Pol2007;61:423–427.
Yan XJ, Liang LZ, Li DC, Li JL, Zhang CQ, Yuan SH.Expression of p21(WAF1) and its relationship with p53 and PCNA protein in epithelial ovarian cancer.Ai Zheng2004;23:74–80.
Yin H-F, Okada N, Takagi M.Apoptosis and apoptotic-related factors in mucoepidermoid carcinoma of the oral minor salivary glands.Pathol Int2000;50:603–609.
Zhang M-F, Zhang Z-Y, Fu J, Yang Y-F, Yun J-P.Correlation between expression of p53, p21/WAF1, and MDM2 proteins and their prognostic significance in primary hepatocellular carcinoma.J Transl Med2009;7:110–117.
Zhu QR, White FH, Tipoe GL.p53 oncoprotein accumulation in adenoid cystic carcinoma of parotid and palatine salivary glands.Pathology1997;29:154–158.
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