Pathology Research International

Pathology Research International / 2017 / Article

Research Article | Open Access

Volume 2017 |Article ID 6794150 |

Nikolaos Koletsas, Triantafyllia Koletsa, Spyros Choidas, Konstantinos Anagnostopoulos, Stavros Touloupidis, Thomas Zaramboukas, Georgia Raptou, Nikolaos Papadopoulos, Maria Lambropoulou, "Immunohistochemical Investigation of HER/AKT/mTOR Pathway and Cellular Adhesion Molecules in Urothelial Carcinomas", Pathology Research International, vol. 2017, Article ID 6794150, 7 pages, 2017.

Immunohistochemical Investigation of HER/AKT/mTOR Pathway and Cellular Adhesion Molecules in Urothelial Carcinomas

Academic Editor: Marco Volante
Received30 Oct 2016
Accepted29 Dec 2016
Published22 Jan 2017


Background. Several investigators have suggested the possibility that the expression of both EGFR and HER2 could be utilized for molecularly targeted therapy in urinary bladder cancer. We tried to evaluate the expression of HER2 and EGFR and activation of the AKT/PTEN/mTOR pathway in urothelial carcinomas and if there is any association between them and cellular adhesion molecules (CAMs). Materials and Methods. Forty-one paraffin-embedded urothelial cancer tissue blocks were collected. Immunostains for HER2, EGFR, MIB1, phospho-AKT, PTEN, phospho-mTOR, e-cadherin, p-cadherin, and b-catenin were performed on tissue microarrays sections. The immunohistochemical results were correlated with clinicopathological parameters. Results. The overexpression of HER2 was found in 19.6% of the cases and it was associated with high grade tumors with a high mitotic index and phosphorylation of AKT and mTOR. Muscle-invasive tumors presented both cytoplasmic and nuclear losses of PTEN expression. There was no association between HER/AKT/mTOR pathway activation and CAM expression. Although cadherins were often coexpressed, only p-cadherin immunoreactivity was associated with tumor grade and high proliferative index. Conclusions. HER2 overexpression is found in a respective proportion of urothelial carcinomas. P-cadherin expression is associated with high grade UCs but it is not affected by HER2 overexpression or by activation of HER/AKT/mTOR pathway.

1. Background

The human epidermal growth factor receptors (HER) protein family consists of four different transmembrane receptors (HER1–HER4). HER1/EGFR and HER2/c-erb-B2 are the most thoroughly investigated family members and have been documented to be involved in the pathogenesis of several types of cancers. In urothelial carcinomas HER1 and HER2 expression has been implicated in tumor aggressiveness, poor outcome, or even pathogenesis [14]. In recent years, their importance has been emphasized due to the development of targeted anti-HER therapy.

The dimerization of HER members leads to the activation of intracellular RAS/MEK/ERK [5] and PI3K/AKT/PTEN/mTOR [6, 7] pathways which plays an important role in cell proliferation, angiogenesis, invasion, and metastasis. The PI3K/AKT/PTEN/mTOR pathway is considered to be essential for cell growth, survival, cell motility, and angiogenesis [811]. The activation of this pathway has been implicated in carcinogenesis or malignant potential of several cancers, including urothelial ones [12, 13].

The categorization of urothelial carcinomas is based on grading and muscle invasion. The majority of urothelial carcinomas are noninvasive tumors of low grade [14]. Muscle invasion carcinomas are characterized by mutations in TP53, RB1, and PIK3CA genes and deletions in PTEN gene [4, 15] and loss of e-cadherin [16]. Cell adhesion molecules (CAMs) are required for maintaining a normal epithelial phenotype and abnormalities in their expression have been related to cancer progression [16].

The present study was conducted to investigate the expression of EGFR and HER2 proteins, as well as intracellular signaling molecules in sections of urothelial carcinomas by immunohistochemistry, to analyze e-cadherin, p-cadherin, and b-catenin expression in low and high grade urothelial carcinomas, and to correlate the immunohistochemical results with clinicopathologic parameters.

2. Materials and Methods

A total of 41 archived cases of urothelial bladder carcinomas were included in this study. Clinical data and complete follow-up were known in 23 patients. The pertinent hematoxylin and eosin (HE) stained sections were retrieved and reevaluated by pathologist and the representative neoplastic areas corresponding to tumor classification and grading were marked for tissue microarrays formation.

2.1. Construction of Tissue Microarrays (TMAs)

Formalin-fixed paraffin-embedded (FFPE) tissue samples from urothelial tumors (paraffin blocks) were collected retrospectively. TMA blocks were constructed with the Alphelys Minicore 3 Tissue Microarray system (Plaisir, France). Each tumor was represented by 3 tissue cores, 1 mm in diameter, which were obtained from the marked representative areas of neoplasms and reembedded in recipient paraffin blocks. TMAs also contained cores from placenta, tonsil and normal thyroid, breast, and renal and colon tissue, used as control markers and for section orientation. Four-micrometer-thick sections were obtained and stained by immunohistochemical (IHC) method.

2.2. Immunohistochemistry

IHC staining was performed on freshly cut sections. Primary antibodies against HER2 (polyclonal, Dako, Glostrup, Denmark), EGFR (clone 31G7, Invitrogen, Carlsbad, CA, USA), phospho-AKT 1/2/3 (Thr308)-R (polyclonal, Santa Cruz Biotechnology, Santa Cruz, CA, USA), PTEN (clone 6h2.1, Dako, Denmark), phospho-mTOR (Ser2448) (clone 49F9, Cell Signaling Technology, Danvers, MA, USA), Ki67 (clone MIB1, Dako, Denmark), E-cadherin (#610181, BD Transduction Laboratories, San Jose, CA, USA), and beta-catenin (#610153, BD Transduction Laboratories, San Jose, CA, USA) were used. IHC stains were performed on a Bond automated stainer (Dako).

2.3. Immunohistochemical Evaluation

There is no standard protocol or guidelines for the estimation of HER2 expression in urothelial carcinomas or what the most appropriate cutoff value is. The HER2 immunostain scoring was performed based on the guidelines of the American Society of Clinical Oncology/College of American Pathologist (0: no staining, 1+: incomplete membranous staining, 2+: complete but weak or moderate membranous staining in >10% of cells, and 3+: strong membranous staining in more than 10% of the cells) [17]. There is no standard protocol for EGFR evaluation. EGFR expression was considered as positive when complete membrane positivity was observed in a percentage of >10% of the cells, as it was used before [18]. For phospho-AKT (pAKT) and PTEN both percentage of positive cells and intensity for nuclear and cytoplasmic immunoreaction were evaluated. The percentage of positive tumor cells (0–100%) was multiplied by dominant staining intensity (1: weak, 2: medium, and 3: intense) and a cutoff value based on the median tumor -score was used, as described by Gonzalez-Roibon et al. [19]. phospho-mTOR (pmTOR) immunostaining was considered negative when expression was observed in <10% of cells and positive if immunoreactivity was found in ≥10% of cells [20]. A tumor was considered to have a high mitotic index when there were positive cells to Ki67/MIB1 antibody in a percentage of >20%.

In 35 cases with adequate specimen immunohistochemistry for CAM expression was also applied. Eighteen out of 35 tumors were of high grade while only ten were invasive. Tumors with positive cells in a percentage >10% was considered positive for e-cadherin, p-cadherin, and b-catenin. According to the intensity of staining tumors were categorized as weak, moderate, and strong [21].

2.4. Statistical Analysis

The statistical software package SPSS v. 21 was used for statistical analyses. Chi-square test was employed to test the dependence between different parameters. Values of 0.05 or less were considered to be statistically significant.

3. Results

3.1. Clinicopathological Characteristics of Patients

Forty-one patients were included in the study, 32 males and 9 females. Their mean age was 68 years (range 47–87). Tumor characteristics are presented in Table 1. Nineteen of the carcinomas were low grade (46.3%) while 22 (53.7%) were of high grade. All tumors with advanced stage were of high grade. Almost one-third of the cases were muscle-invasive tumors. Patients with stages pTa and pT1 were treated either with epirubicin or BCG depending on histological grade, tumor size, and multiplicity. Radical cystectomy was followed for those patients with invasive tumors. Chemotherapy was added in two cases with metastatic disease. A third patient underwent only radiotherapy due to the small size of a solitary lesion located on the frontal bladder wall.


Low grade1946.3
High grade2253.7
<3 cm2458.5
≥3 cm1741.5
One lesion2048.8
Missing data49.8

3.2. Immunohistochemical Distribution of the Markers

The immunohistochemical results are summarized in Table 2. HER2 overexpression (3+) was found in 8 cases (19.6%), seven of which were of high grade (). HER2 2+ and 3+ immunoscores accounted for almost 46.4% and were mainly found in high grade tumors (). Sixty percent of HER2 3+ tumors measured more than 3 cm (). HER2 expression exhibited positive correlation with pAKT cytoplasmic and nuclear immunoreactivity ( and , resp.) (Figure 1). Moreover, in 12 out of 19 HER2 positive cases, pmTOR was coexpressed (). The majority of the HER2 positive cases had high mitotic index (), defined as >20% positive cells to Ki67/MIB1 antibody.




pAKT nuclear

pAKT cytoplasmic

PTEN cytoplasmic
 Missing data1

PTEN nuclear
 Missing data1

PTEN nuclear/cytoplasmic
 Missing data1



 Missing data6

 Missing data7

 Missing data6

HER2/EGFR coexpression was observed in four cases (9.75%). There was no association between EGFR expression (14/41, 34.14%) or HER2/EGFR coexpression (4/41, 9.75%) and the examined clinicopathologic parameters (, ).

Fifteen out of eighteen high grade cases (83.3%) presented high mitotic indices (). MIB1 positivity was associated with HER2 positivity () and pmTOR cytoplasmic () expression ().

Loss of PTEN cytoplasmic expression was found mainly in muscle-invasive tumors () (Table 3). A loss of PTEN expression was defined as simultaneous lack of nuclear and cytoplasmic immunoreactivity. Muscle-invasive tumors presented commonly a loss of PTEN expression (). None of the cases without cytoplasmic PTEN staining exhibited cytoplasmic expression of pAKT (). PTEN cytoplasmic expression was positively associated with the cytoplasmic expression of pmTOR protein (). However, lack of PTEN nuclear immunoreactivity was not associated with any of the other studied markers, apart from a trend of negative association observed with pAKT nuclear expression (). In three cases PTEN was immunoreactive in membranes, as well.

Muscle-invasive UC (pT2–pT4)Non-muscle-invasive UC (pTa-pT1) value



 Nuclear positive1680.790
 Nuclear negative512

 Cytopl positive290.315
 Cytopl negative1119


 Nuclear positive180.120
 Nuclear negative1219
 Missing data01

 Cytopl positive3180.01
 Cytopl negative109
 Missing data01

 Missing data33

 Missing data43

 Missing data33

Cytopl: cytoplasmic; UC: urothelial carcinomas.

The majority of the muscle-invasive tumors (pT2–pT4) (9/13, 69.2%) expressed pmTOR protein compared to pTa-pT1 urothelial carcinomas () (Table 3). Cytoplasmic pmTOR expression was associated with high MIB1 labeling index () and neoplastic invasion (). Notably, membranous immunoreactivity to pmTOR was found in seven cases.

In this cohort, HER2 overexpression along with pAKT nuclear expression, both nuclear and cytoplasmic PTEN deletion and pmTOR expression, was found in three of the patients. Two of them coexpressed the EGFR protein, and they had the worst prognosis.

Expression of e-cadherin and p-cadherin was observed in 54.3% (19/35) and 41.2% (14/34) of the cases, respectively (Table 2). There was no association between CAM expression and tumor size (Table 3) or aggressive behavior (, ). Fifteen out of 19 tumors with stage pTa were negative to p-cadherin antibody, reflecting a trend of association between stage and protein expression of this marker (, ). A positive association was observed between e-cadherin and p-cadherin expression () (Figure 2). The majority of the cases (25/35, 71.4%) expressed b-catenin. E-cadherin and p-cadherin positive tumors were mainly of high grade (, and , resp.). P-cadherin expression was mostly found in tumors with high mitotic indices (MIB1 > 20%) (, ). There was no association between CAM expression and muscle-invasive tumors (, ), pointing out the small sample of the tumors examined for these adhesion molecules. Of note, a case of sarcomatoid carcinoma included in the study exhibited no immunoreactivity to antibodies for CAMs (Figure 2).

4. Discussion

Over the last decade, two of the HER family members, HER1/EGFR and HER2, have been researched extensively in the context of various types of cancer. Apart from their role in tumor proliferation, infiltration, and metastatic potential [22], the increasing interest in them derives from being targets of newly developed and FDA approved therapies. HER2 expression in urothelial carcinomas has been reported in several percentages ranging from 9% to 74.8% [2325]. This discrepancy is mainly attributed to the differences in the used cutoffs and the constitution of cohorts, that is, the aggressiveness of the cases included in a study.

Notably, many studies defined HER2 overexpression as both HER2 2+ and 3+ immunoscores in urothelial carcinomas [25], as opposed to breast carcinomas. Scoring of the HercepTest corresponds to the number of extracellular domains located in the membrane [26]. In several types of cancer, such as breast carcinomas or gastric/gastroesophageal carcinomas, there are guidelines for protein expression evaluation and criteria for determining overexpression [17, 27, 28]. In urothelial carcinomas there are varying methods and cutoffs used by several studies. However, in a large cohort, Laé et al. [25] found that a true HER2 overexpression in bladder carcinomas corresponded to HER2 gene amplification, being defined in the same way as in breast cancer.

In the present study, HER2 3+ was observed in 19.6% of the cases, while HER2 2+ and 3+ account for 46.4%. The observed association between tumor grade and HER2 expression has been previously well documented [29, 30]. In addition, the aforementioned associations between HER2 expression and tumor size, pAKT, and pmTOR expression indicate that the PI3K/AKT/mTOR pathway could be activated by HER dimerization. Indeed, cases with HER2 overexpression (HER2 3+) were of high grade and they were usually characterized by pAKT and pmTOR protein overexpression and PTEN nuclear deletion. This was the immunophenotypic profile of the tumors of the two patients that presented the worst prognosis in this study. In one of these tumors, EGFR coexpression was also observed, which suggests that both AKT/PTEN/TOR and RAS/MEK/ERK pathways were activated. The increased interest to personalize therapy leads to a thorough investigation of patients who will benefit the most from a particular treatment. Hence, these patients could be the most appropriate candidates for targeted therapy, when conventional therapy fails, taking into account the side effects of these therapeutic options [31].

PTEN deletion affected more often the nucleus than the cytoplasm, a finding in line with those of previous reported studies [32, 33], and it could be found in noninfiltrating tumors but it occurs more often in muscle-invasive ones [3436]. PTEN deletion is also observed in tumors without HER/AKT/mTOR pathway activation [35, 37], as found in our study, suggesting that PTEN loss is not always responsible for AKT activation, adding that it may be involved in other pathways [37], as it is known that different intracellular pathways are linked through cross-talking [38] or that synergistic action of different pathways is essential for carcinogenesis or aggressive biological behavior [39].

It has been reported that inactivation of p53 and inactivation of PTEN are the principal adverse prognostic markers [40]. In addition, PTEN deletion in combination with altered p53 leads to deregulation of the mTOR pathway and, consequently, reinforces the use of newly therapeutic agents, such as rapamycin [41], everolimus (RAD001) [42], or a combination of mTOR and PI3K inhibitors [4345].

The cadherins are a group of membrane glycoprotein and the mediators of cell to cell adhesion. E-cadherin, which is an epithelial-specific cadherin, plays a major role in the selective adhesion of cells in epithelial tissue and is necessary for the maintenance of normal epithelial cells integrity. Abnormal expression of p-cadherin has been associated with an invasive and aggressive phenotype of UCs and it has been hypothesized that it may act as a key effector of muscle invasion [46]. CAMs in this study was generally coexpressed, especially in high grade tumors, but they were not associated with infiltration status, a finding that may be biased due to small sample of infiltrative tumors. As previously mentioned [46], and confirmed by this study, p-cadherin seems to be commonly expressed in high grade tumors exhibiting high mitotic index. HER pathway does not appear to affect CAM expression.

In conclusion, HER2 overexpression is found in a respective proportion of urothelial carcinomas and it seems to characterize an aggressive tumor behavior. The combination of pAKT and pmTOR expression along with a loss of PTEN expression is associated with adverse clinicopathological characteristics. P-cadherin is associated with high grade UCs but its expression is not affected by HER2 overexpression or by activation of HER/AKT/mTOR pathway.

Competing Interests

The authors declare that they have no competing interests.


  1. C. Bolenz, S. F. Shariat, P. I. Karakiewicz et al., “Human epidermal growth factor receptor 2 expression status provides independent prognostic information in patients with urothelial carcinoma of the urinary bladder,” BJU International, vol. 106, no. 8, pp. 1216–1222, 2010. View at: Publisher Site | Google Scholar
  2. N.-H. Chow, H.-S. Liu, E. I. C. Lee et al., “Significance of urinary epidermal growth factor and its receptor expression in human bladder cancer,” Anticancer Research, vol. 17, no. 2B, pp. 1293–1296, 1997. View at: Google Scholar
  3. M. Enache, C. E. Simionescu, and A. Stepan, “EGFR and Her2/neu immunoexpression in papillary urothelial bladder carcinomas,” Romanian Journal of Morphology and Embryology, vol. 54, no. 1, pp. 137–141, 2013. View at: Google Scholar
  4. P. Korkolopoulou, G. Levidou, E.-A. Trigka et al., “A comprehensive immunohistochemical and molecular approach to the PI3K/AKT/mTOR (phosphoinositide 3-kinase/v-akt murine thymoma viral oncogene/mammalian target of rapamycin) pathway in bladder urothelial carcinoma,” BJU International, vol. 110, no. 11, pp. E1237–E1348, 2012. View at: Publisher Site | Google Scholar
  5. M. Campiglio, S. Ali, P. G. Knyazev, and A. Ullrich, “Characteristics of EGFR family-mediated HRG signals in human ovarian cancer,” Journal of Cellular Biochemistry, vol. 73, no. 4, pp. 522–532, 1999. View at: Publisher Site | Google Scholar
  6. N. V. Sergina, M. Rausch, D. Wang et al., “Escape from HER-family tyrosine kinase inhibitor therapy by the kinase-inactive HER3,” Nature, vol. 445, no. 7126, pp. 437–441, 2007. View at: Publisher Site | Google Scholar
  7. S. P. Soltoff, K. L. Carraway III, S. A. Prigent, W. G. Gullick, and L. C. Cantley, “ErbB3 is involved in activation of phosphatidylinositol 3-kinase by epidermal growth factor,” Molecular and Cellular Biology, vol. 14, no. 6, pp. 3550–3558, 1994. View at: Publisher Site | Google Scholar
  8. R. J. Shaw and L. C. Cantley, “Ras, PI(3)K and mTOR signalling controls tumour cell growth,” Nature, vol. 441, no. 7092, pp. 424–430, 2006. View at: Publisher Site | Google Scholar
  9. K. D. Courtney, R. B. Corcoran, and J. A. Engelman, “The PI3K pathway as drug target in human cancer,” Journal of Clinical Oncology, vol. 28, no. 6, pp. 1075–1083, 2010. View at: Publisher Site | Google Scholar
  10. C. Bartholomeusz and A. M. Gonzalez-Angulo, “Targeting the PI3K signaling pathway in cancer therapy,” Expert Opinion on Therapeutic Targets, vol. 16, no. 1, pp. 121–130, 2012. View at: Publisher Site | Google Scholar
  11. H. Pópulo, J. M. Lopes, and P. Soares, “The mTOR signalling pathway in human cancer,” International Journal of Molecular Sciences, vol. 13, no. 2, pp. 1886–1918, 2012. View at: Publisher Site | Google Scholar
  12. M. A. Knowles, F. M. Platt, R. L. Ross, and C. D. Hurst, “Phosphatidylinositol 3-kinase (PI3K) pathway activation in bladder cancer,” Cancer and Metastasis Reviews, vol. 28, no. 3-4, pp. 305–316, 2009. View at: Publisher Site | Google Scholar
  13. J. M. Askham, F. Platt, P. A. Chambers, H. Snowden, C. F. Taylor, and M. A. Knowles, “AKT1 mutations in bladder cancer: identification of a novel oncogenic mutation that can co-operate with E17K,” Oncogene, vol. 29, no. 1, pp. 150–155, 2010. View at: Publisher Site | Google Scholar
  14. M. Burger, W. Oosterlinck, B. Konety et al., “ICUD-EAU international consultation on bladder cancer 2012: non-muscle-invasive urothelial carcinoma of the bladder,” European Urology, vol. 63, no. 1, pp. 36–44, 2013. View at: Publisher Site | Google Scholar
  15. S. Z. Millis, D. Bryant, G. Basu et al., “Molecular profiling of infiltrating urothelial carcinoma of bladder and nonbladder origin,” Clinical Genitourinary Cancer, vol. 13, no. 1, pp. e37–e49, 2015. View at: Publisher Site | Google Scholar
  16. W. Sun and G. A. Herrera, “E-cadherin expression in invasive urothelial carcinoma,” Annals of Diagnostic Pathology, vol. 8, no. 1, pp. 17–22, 2004. View at: Publisher Site | Google Scholar
  17. A. C. Wolff, M. E. Hammond, D. G. Hicks et al., “American Society of Clinical Oncology; College of American Pathologists. Recommendations for human epidermal growth factor receptor 2 testing in breast cancer: American Society of Clinical Oncology/College of American Pathologists clinical practice guideline update,” Journal of Clinical Oncology, vol. 31, no. 31, pp. 3997–4013, 2013. View at: Publisher Site | Google Scholar
  18. S. Leibl, R. Zigeuner, G. Hutterer, T. Chromecki, P. Rehak, and C. Langner, “EGFR expression in urothelial carcinoma of the upper urinary tract is associated with disease progression and metaplastic morphology,” Acta Pathologica, Microbiologica, et Immunologica Scandinavica, vol. 116, no. 1, pp. 27–32, 2008. View at: Publisher Site | Google Scholar
  19. N. D. Gonzalez-Roibon, A. Chaux, T. Al-Hussain et al., “Dysregulation of mammalian target of rapamycin pathway in plasmacytoid variant of urothelial carcinoma of the urinary bladder,” Human Pathology, vol. 44, no. 4, pp. 612–622, 2013. View at: Publisher Site | Google Scholar
  20. J. Afonso, A. Longatto-Filho, V. M. Da Silva, T. Amaro, and L. L. Santos, “Phospho-mTOR in non-tumour and tumour bladder urothelium: pattern of expression and impact on urothelial bladder cancer patients,” Oncology Letters, vol. 8, no. 4, pp. 1447–1454, 2014. View at: Publisher Site | Google Scholar
  21. S. T. dos Reis, K. R. M. Leite, A. M. Neto et al., “Immune expression of E-cadherin and α, β and γ-catenin adhesion molecules and prognosis for upper urinary tract urothelial carcinomas,” International Braz J Urol, vol. 38, no. 4, pp. 466–473, 2012. View at: Publisher Site | Google Scholar
  22. S. Kaptain, L. K. Tan, and B. Chen, “Her-2/neu and breast cancer,” Diagnostic Molecular Pathology, vol. 10, no. 3, pp. 139–152, 2001. View at: Publisher Site | Google Scholar
  23. D. A. Pigott, A. J. Proctor, M. E. Eydmann et al., “Amplification and over-expression of c-erbB-2 in transitional cell carcinoma of the urinary bladder,” British Journal of Cancer, vol. 63, no. 4, pp. 601–608, 1991. View at: Publisher Site | Google Scholar
  24. C. Wülfing, D. Von Struensee, S. Bierer, M. Bögemann, L. Hertle, and E. Eltze, “ExpressIon of her2/neu in locally advanced bladder cancer: implication for a molecular targeted therapy,” Aktuelle Urologie, vol. 36, no. 5, pp. 423–429, 2005. View at: Publisher Site | Google Scholar
  25. M. Laé, J. Couturier, S. Oudard, F. Radvanyi, P. Beuzeboc, and A. Vieillefond, “Assessing HER2 gene amplification as a potential target for therapy in invasive urothelial bladder cancer with a standardized methodology: results in 1005 patients,” Annals of Oncology, vol. 21, no. 4, pp. 815–819, 2009. View at: Publisher Site | Google Scholar
  26. J. S. Ross, J. A. Fletcher, K. J. Bloom et al., “Targeted therapy in breast cancer: the HER-2/neu gene and protein,” Molecular & Cellular Proteomics, vol. 3, no. 4, pp. 379–398, 2004. View at: Publisher Site | Google Scholar
  27. L. Albarello, L. Pecciarini, and C. Doglioni, “HER2 testing in gastric cancer,” Advances in Anatomic Pathology, vol. 18, no. 1, pp. 53–59, 2011. View at: Publisher Site | Google Scholar
  28. F. De Vita, F. Giuliani, N. Silvestris, G. Catalano, F. Ciardiello, and M. Orditura, “Human epidermal growth factor receptor 2 (HER2) in gastric cancer: a new therapeutic target,” Cancer Treatment Reviews, vol. 36, no. 3, pp. S11–S15, 2010. View at: Publisher Site | Google Scholar
  29. S. Krüger, G. Weitsch, H. Büttner et al., “HER2 overexpression in muscle-invasive urothelial carcinoma of the bladder: prognostic implications,” International Journal of Cancer, vol. 102, no. 5, pp. 514–518, 2002. View at: Publisher Site | Google Scholar
  30. A. Alexa, F. Baderca, D. E. Zăhoi, R. Lighezan, D. Izvernariu, and M. Raica, “Clinical significance of Her2/neu overexpression in urothelial carcinomas,” Romanian Journal of Morphology and Embryology, vol. 51, no. 2, pp. 277–282, 2010. View at: Google Scholar
  31. P. H. Abbosh, D. J. McConkey, and E. R. Plimack, “Targeting signaling transduction pathways in bladder cancer,” Current Oncology Reports, vol. 17, no. 12, article 58, 2015. View at: Publisher Site | Google Scholar
  32. H. Tsuruta, H. Kishimoto, T. Sasaki et al., “Hyperplasia and carcinomas in Pten-deficient mice and reduced PTEN protein in human bladder cancer patients,” Cancer Research, vol. 66, no. 17, pp. 8389–8396, 2006. View at: Publisher Site | Google Scholar
  33. F. M. Platt, C. D. Hurst, C. F. Taylor, W. M. Gregory, P. Harnden, and M. A. Knowles, “Spectrum of phosphatidylinositol 3-kinase pathway gene alterations in bladder cancer,” Clinical Cancer Research, vol. 15, no. 19, pp. 6008–6017, 2009. View at: Publisher Site | Google Scholar
  34. L. Schultz, R. Albadine, J. Hicks et al., “Expression status and prognostic significance of mammalian target of rapamycin pathway members in urothelial carcinoma of urinary bladder after cystectomy,” Cancer, vol. 116, no. 23, pp. 5517–5526, 2010. View at: Publisher Site | Google Scholar
  35. C. Cordon-Cardo, “Molecular alterations associated with bladder cancer initiation and progression,” Scandinavian Journal of Urology and Nephrology, vol. 42, no. 218, pp. 154–165, 2008. View at: Publisher Site | Google Scholar
  36. W. Tian and J. I. Epstein, “Invasive low-grade papillary urothelial carcinoma: an immunohistochemical study of 26 cases,” Human Pathology, vol. 46, no. 12, pp. 1836–1841, 2015. View at: Publisher Site | Google Scholar
  37. M. Castillo-Martin, J. Domingo-Domenech, O. Karni-Schmidt, T. Matos, and C. Cordon-Cardo, “Molecular pathways of urothelial development and bladder tumorigenesis,” Urologic Oncology: Seminars and Original Investigations, vol. 28, no. 4, pp. 401–408, 2010. View at: Publisher Site | Google Scholar
  38. N. Houédé and P. Pourquier, “Targeting the genetic alterations of the PI3K-AKT-mTOR pathway: its potential use in the treatment of bladder cancers,” Pharmacology & Therapeutics, vol. 145, pp. 1–18, 2015. View at: Publisher Site | Google Scholar
  39. I. Ahmad, J. P. Morton, L. B. Singh et al., “β-Catenin activation synergizes with PTEN loss to cause bladder cancer formation,” Oncogene, vol. 30, no. 2, pp. 178–189, 2011. View at: Publisher Site | Google Scholar
  40. A. M. Puzio-Kuter, M. Castillo-Martin, C. W. Kinkade et al., “Inactivation of p53 and Pten promotes invasive bladder cancer,” Genes & Development, vol. 23, no. 6, pp. 675–680, 2009. View at: Publisher Site | Google Scholar
  41. G. Fechner, K. Claßen, D. Schmidt, S. Hauser, and S. C. Müller, “apamycin inhibits in vitro growth and release of angiogenetic factors in human bladder cancer,” Urology, vol. 73, no. 3, pp. 665–668, 2009. View at: Publisher Site | Google Scholar
  42. J. J. Mansure, R. Nassim, S. Chevalier, J. Rocha, E. Scarlata, and W. Kassouf, “Inhibition of mammalian target of rapamycin as a therapeutic strategy in the management of bladder cancer,” Cancer Biology and Therapy, vol. 8, no. 24, pp. 2339–2347, 2009. View at: Google Scholar
  43. B. Markman, R. Dienstmann, and J. Tabernero, “Targeting the PI3K/Akt/mTOR pathway–beyond rapalogs,” Oncotarget, vol. 1, no. 7, pp. 530–543, 2010. View at: Publisher Site | Google Scholar
  44. E. Seront, A. Pinto, C. Bouzin, L. Bertrand, J.-P. Machiels, and O. Feron, “PTEN deficiency is associated with reduced sensitivity to mTOR inhibitor in human bladder cancer through the unhampered feedback loop driving PI3K/Akt activation,” British Journal of Cancer, vol. 109, no. 6, pp. 1586–1592, 2013. View at: Publisher Site | Google Scholar
  45. A. Bagrodia, L.-M. Krabbe, B. A. Gayed et al., “Evaluation of the prognostic significance of altered mammalian target of rapamycin pathway biomarkers in upper tract urothelial carcinoma,” Urology, vol. 84, no. 5, pp. 1134–1140, 2014. View at: Publisher Site | Google Scholar
  46. R. T. Bryan, “Cell adhesion and urothelial bladder cancer: the role of cadherin switching and related phenomena,” Philosophical Transactions of the Royal Society of London, Series B: Biological Sciences, vol. 370, no. 1661, Article ID 20140042, 2015. View at: Publisher Site | Google Scholar

Copyright © 2017 Nikolaos Koletsas et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

More related articles

 PDF Download Citation Citation
 Download other formatsMore
 Order printed copiesOrder

Related articles

We are committed to sharing findings related to COVID-19 as quickly as possible. We will be providing unlimited waivers of publication charges for accepted research articles as well as case reports and case series related to COVID-19. Review articles are excluded from this waiver policy. Sign up here as a reviewer to help fast-track new submissions.