Abnormal Protein Glycosylation and Activated PI3K/Akt/mTOR Pathway: Role in Bladder Cancer Prognosis and Targeted Therapeutics

• Published in: PloS one Vol. 10; no. 11; p. e0141253
• Main Authors: Costa, Céu, Pereira, Sofia, Lima, Luís, Peixoto, Andreia, Fernandes, Elisabete, Neves, Diogo, Neves, Manuel, Gaiteiro, Cristiana, Tavares, Ana, Gil da Costa, Rui M, Cruz, Ricardo, Amaro, Teresina, Oliveira, Paula A, Ferreira, José Alexandre, Santos, Lúcio L
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 16.11.2015; Public Library of Science (PLoS)
• Subjects: 1-Phosphatidylinositol 3-kinase; Activation; Adult; Aged; Aged, 80 and over; AKT protein; Animal diseases; Animals; Antigens; Antigens, Tumor-Associated, Carbohydrate - metabolism; Biomarkers; Bladder; Bladder cancer; Cancer; Female; Gene expression; Gene Expression Regulation, Neoplastic; Glycosylation; Health risks; Health sciences; Humans; Intermediates; Invasiveness; Kinases; Lesions; Male; Medical prognosis; Medical treatment; Methyl isobutyl carbinol; Mice; Mice, Inbred ICR; Middle Aged; Mimicry; Muscles; Neoplasm Staging; Oncology; Pathology; Pessoa, Fernando Antonio Nogueira (1888-1935); Phosphatidylinositol 3-Kinases - metabolism; Prognosis; Proportional Hazards Models; Proteins; Proto-Oncogene Proteins c-akt - metabolism; PTEN protein; Rapamycin; Regression analysis; Retrospective Studies; Signal Transduction; Survival; TOR protein; TOR Serine-Threonine Kinases - metabolism; Treatment Outcome; Tumors; Urinary Bladder Neoplasms - diagnosis; Urinary Bladder Neoplasms - metabolism; Urinary Bladder Neoplasms - mortality; Urinary Bladder Neoplasms - therapy; Urology; Portugal
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0141253

Muscle invasive bladder cancer (MIBC, stage ≥T2) is generally associated with poor prognosis, constituting the second most common cause of death among genitourinary tumours. Due to high molecular heterogeneity significant variations in the natural history and disease outcome have been observed. This has also delayed the introduction of personalized therapeutics, making advanced stage bladder cancer almost an orphan disease in terms of treatment. Altered protein glycosylation translated by the expression of the sialyl-Tn antigen (STn) and its precursor Tn as well as the activation of the PI3K/Akt/mTOR pathway are cancer-associated events that may hold potential for patient stratification and guided therapy. Therefore, a retrospective design, 96 bladder tumours of different stages (Ta, T1-T4) was screened for STn and phosphorylated forms of Akt (pAkt), mTOR (pmTOR), S6 (pS6) and PTEN, related with the activation of the PI3K/Akt/mTOR pathway. In our series the expression of Tn was residual and was not linked to stage or outcome, while STn was statically higher in MIBC when compared to non-muscle invasive tumours (p = 0.001) and associated decreased cancer-specific survival (log rank p = 0.024). Conversely, PI3K/Akt/mTOR pathway intermediates showed an equal distribution between non-muscle invasive bladder cancer (NMIBC) and MIBC and did not associate with cancer-specif survival (CSS) in any of these groups. However, the overexpression of pAKT, pmTOR and/or pS6 allowed discriminating STn-positive advanced stage bladder tumours facing worst CSS (p = 0.027). Furthermore, multivariate Cox regression analysis revealed that overexpression of PI3K/Akt/mTOR pathway proteins in STn+ MIBC was independently associated with approximately 6-fold risk of death by cancer (p = 0.039). Mice bearing advanced stage chemically-induced bladder tumours mimicking the histological and molecular nature of human tumours were then administrated with mTOR-pathway inhibitor sirolimus (rapamycin). This decreased the number of invasive lesions and, concomitantly, the expression of STn and also pS6, the downstream effector of the PI3K/Akt/mTOR pathway. In conclusion, STn was found to be marker of poor prognosis in bladder cancer and, in combination with PI3K/Akt/mTOR pathway evaluation, holds potential to improve the stratification of stage disease. Animal experiments suggest that mTOR pathway inhibition could be a potential therapeutic approach for this specific subtype of MIBC.