Nuclear localization of E-cadherin but not beta-catenin in human ovarian granulosa cell tumours and normal ovarian follicles and ovarian stroma

Ohishi Y, Oda Y, Kurihara S, Kaku T, Kobayashi H, Wake N & Tsuneyoshi M
(2011) Histopathology 58 , 423–432
Nuclear localization of E‐cadherin but not beta‐catenin in human ovarian granulosa cell tumours and normal ovarian follicles and ovarian stroma Aims: The role of misregulated Wnt/beta‐catenin signalling in human ovarian granulosa cell tumour (GCT) has not been well characterized. The aim of this study was to confirm subcellular localization of key molecules of Wnt signalling (beta‐catenin and E‐cadherin) in human ovarian GCTs. Methods and results: Tissue samples taken from 32 human ovarian GCTs and 19 human normal ovaries containing 68 follicles were stained immunohistochemically using monoclonal anti‐beta‐catenin and anti‐E‐cadherin antibodies. None of the 32 GCTs and none of the 68 ovarian follicles showed beta‐catenin nuclear expression (0%). On the other hand, 28 of 32 GCTs (88%) and 53 of 68 normal ovarian follicles (78%) showed nuclear expression of E‐cadherin in granulosa cells. The ovarian stroma in all 19 normal ovaries showed nuclear expression of E‐cadherin but not beta‐catenin. Membranous and cytoplasmic expression was observed variously in ovarian GCT, follicles and stroma. Conclusions: We have confirmed frequent nuclear localization of E‐cadherin but not beta‐catenin in human ovarian GCT, ovarian follicles and stroma. There is no evidence of misregulated Wnt/beta‐catenin signalling (represented by nuclear expression of beta‐catenin) in human ovarian GCT. Nuclear translocation of E‐cadherin might contribute to ovarian folliculogenesis or granulosa/stromal cell differentiation.     

Genetic alteration and immunohistochemical staining patterns of ovarian high‐grade serous adenocarcinoma with special emphasis on p53 immnnostaining pattern

We evaluated p53, KRAS, BRAF and CTNNB1 mutation and p53, WT1, p16 and beta‐catenin expression in 31 ovarian high‐grade serous adenocarcinoma. Twenty‐five (80.6%) tumors contained functional mutations of p53; three frameshift, four nonsense and 19 missense mutations. None of the tumors showed KRAS, BRAF or CTNNB1 mutation. In all 18 tumors with missense mutations, ≥60% of tumor cells were strongly positive for p53 immunostaining whereas all tumors with frameshift or nonsense mutations were completely negative. Missense mutation was correlated with diffuse and strong imunoreaction and frameshift/nonsense mutation was correlated with completely negative immunoreaction (P = 0.000). Tumors with wild‐type p53 revealed a wide range of immunostaining patterns. In 27 (87.1%) and 18 (58.1%) tumors, ≥50% of tumor cells were moderate to strongly positive for WT1 and p16, respectively. A considerable intratumoral heterogeneity for p16 expression was present. None of the tumors demonstrated nuclear beta‐catenin expression. p53 mutations appear to be a powerful molecular marker for ovarian high‐grade serous adenocarcinoma. Using p53 with an appropriate interpretation criteria together with WT1, p16 and beta‐catenin, most of the high‐grade serous adenocarcinoma could be distinguished from other ovarian tumors.     

Immunohistochemical expression of SPARC is correlated with recurrence,survival and malignant potential in meningiomas

Meningioma is a common neoplasm that constitutes almost 30% of all primary central nervous system tumors and is associated with inconsistent clinical outcomes. The extracellular matrix proteins play a crucial role in meningioma cell biology and are important in tumor cell invasion and in progression to malignancy. SPARC (secreted protein, acidic and rich in cysteine) (osteonectin) is a matricellular glycoprotein that regulates cell function by interacting with different extracellular matrix proteins. The aim of this study was to evaluate the expression of SPARC with proliferation index, p53 reactivity in WHO grade 1 (benign), grade 2 (atypical) and grade 3 (anaplastic) meningiomas and correlate with clinical features of the patients, including location of the tumor, recurrence of the tumor and survival of patients. We studied 111 meningiomas, 69 being benign, 34 being atypical and eight being anaplastic meningiomas of various histological types. Using immunohistochemical analysis, we evaluated the expression of SPARC, Ki‐67 (MIB‐1) and p53 in meningiomas. Immunohistochemical scores of SPARC were determined as the sum of frequency (0–3) and intensity (0–3) of immunolabeling of the tumor cells. A high immunohistochemical score (4–6) for SPARC was more frequent in atypical and in anaplastic meningiomas than in benign meningiomas (p < 0.01). MIB‐1 proliferation index showed significant association between tumor grades in meningiomas (p < 0.01). At the end of a follow‐up period of 47.53 ± 25.04 months, 30 tumors recurred. A high SPARC expression was significantly associated with tumor recurrence (p = 0.02). The immunoreactivity of p53 protein and MIB‐1 score were significantly higher in recurrent meningiomas than in non‐recurrent meningiomas. The cumulative survival of patients with high SPARC expression was significantly lower than patients with low SPARC expression. The high SPARC expression scores were predominantly identified in meningothelial, fibrous and chordoid meningiomas; low SPARC expression scores were mostly spotted in secretory and psammomatous meningiomas. Evaluating SPARC expression might help assessing recurrence risk and survival estimation in meningiomas.     

The significance of immunohistochemical expression of Ki-67, p53, p21, and p16 in meningiomas tissue arrays

Although histologic grading of meningiomas has prognostic and clinical implications, it is difficult in some cases to predict the outcome of patients. There have been several efforts to evaluate the use of different immunohistochemical markers for predicting meningioma prognosis. We analyzed the immunohistochemical expression of Ki-67, p53, p21, p16, and PTEN proteins in 130 meningiomas (64 benign, 39 atypical, and 27 malignant meningiomas) using tissue microarray. The tumors were graded according to the World Health Organization classification. There was a statistically significant correlation between the expression of Ki-67, p53, p21, p16, and the grade of meningiomas (p0.001). By ordinal logistic regression, p53 and Ki-67 were significantly associated with grade, and an increase of 1% in the labeling index of these markers resulted in an increase in the risk of raising the grade by 2.17 and 1.49, respectively. Histological grade, p53, Ki-67 labeling indices, and overexpression of p16 were strongly associated with decreased event-free survival in univariate analysis. In contrast, multivariate analysis revealed that only tumor grade is an independent factor for predicting meningioma recurrence. We conclude that the Ki-67 and p53 labeling indices are useful additional tools in discriminating atypical from benign or anaplastic meningiomas, especially in histological borderline cases.     

Tensin4 (TNS4) is upregulated by Wnt signalling in adenomas in multiple intestinal neoplasia (Min) mice

Apc^Min/+ mice are regarded as a standard animal model of colorectal cancer (CRC). Tensin4 (TNS4 or Cten) is a putative oncogene conferring features of stemness and promoting motility. Our objective was to assess TNS4 expression in intestinal adenomas and determine whether TNS4 is upregulated by Wnt signalling. Apc^Min/+ mice (n = 11) were sacrificed at approximately 120 days old at the onset of anaemia signs. Small intestines were harvested, and Swiss roll preparations were tested for TNS4 expression by immunohistochemistry (IHC). Individual polyps were also separately collected (n = 14) and tested for TNS4 mRNA expression and Kras mutation. The relationship between Wnt signalling and TNS4 expression was tested by Western blotting in the human CRC cell line HCT116 after inhibition of β‐catenin activity with MSAB or its increase by transfection with a Flag β‐catenin expression vector. Overall, 135/148 (91.2%) of the total intestinal polyps were positive for TNS4 expression by IHC, whilst adjacent normal areas were negative. RT‐qPCR analysis showed approximately 5‐fold upregulation of TNS4 mRNA in the polyps compared to adjacent normal tissue and no Kras mutations were detected. In HCT116, β‐catenin inhibition resulted in reduced TNS4 expression, and conversely, β‐catenin overexpression resulted in increased TNS4 expression. In conclusion, this is the first report linking aberrant Wnt signalling to upregulation of TNS4 both during initiation of intestinal adenomas in mice and in in vitro models. The exact contribution of TNS4 to adenoma development remains to be investigated, but the Apc^Min/+ mouse represents a good model to study this.     

The biological and clinical value of p53 expression in pelvic high‐grade serous carcinomas

Studies on the p53 expression and outcome for women with ovarian carcinoma have produced conflicting results. The observed heterogeneity may be due to the range of cut‐offs used to define overexpression and the mix of histotypes of the study cohorts. We aimed to examine the association between p53 expression and biological properties of tumours as well as outcome in 502 pelvic high‐grade serous carcinomas (HGSCs) derived from two population‐based cohorts from British Columbia representing cases with or without residual tumour after initial surgery, respectively, and one clinical trial cohort from Germany (AGO‐OVAR‐3). p53 expression was assessed on tissue microarrays by immunohistochemistry using the DO‐7 antibody. p53 expression was scored in three tiers as complete loss of expression, focal expression or overexpression (defined as more than 50% positive tumour cell nuclei) and correlated with survival using multivariate Cox regression models. p53 was completely absent in 30.3%, focally expressed in 12.0%, and overexpressed in 57.7% of HGSCs, which was an inverse pattern compared to clear cell and endometrioid types of ovarian carcinomas, where 76% and 69% of cases showed focal expression, respectively (p < 0.001, chi square test). Pelvic HGSCs show either complete absence of p53 expression or p53 overexpression in 88% of cases; thus, aberrant p53 expression is a ubiquitous feature of HGSCs. HGSCs with p53 overexpression were associated with a reduced risk of recurrence compared to cases with complete absence of p53 in the British Columbia cohort with residual tumour (HR = 0.71, 95% CI 0.51–0.99) and for a combination of all three cohorts (HR = 0.70, 95% CI 0.55–0.89) in multivariate analysis including age, stage, residual tumour, and stratification by cohort. The association of complete absence of p53 expression with unfavourable outcome suggests functional differences of TP53 mutations underlying overexpression, compared to those underlying complete absence of expression. Copyright © 2010 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

EZH2 expression is dependent on MYC and TP53 regulation in diffuse large B-cell lymphoma

EZH2 is an important epigenetic regulator, but its role in diffuse large B-cell lymphoma (DLBCL) pathogenesis and its relationship with MYC, BCL2, and TP53 expression, chromosomal rearrangements, and clinical features are still poorly understood. So, we investigated EZH2 expression and its associations with the immunophenotypic presentations, including MYC, BCL2, and TP53 expression, MYC, BCL2, and BCL6 translocation status, clinicopathological features, and therapeutic response to R-CHOP in a series of 139 DLBCL cases. EZH2 positivity was associated with MYC and TP53 expression (p = 0.0002 and p = 0.0000, respectively) and to high proliferative index (Ki67>70%, p = 0.0082). No associations were found among EZH2 expression and chromosomal translocation status. The non-germinal center (nGC) DLBCL presented most of associations observed in the general sample; however, only TP53 immunodetection showed associations with EZH2 expression in the germinal center (GC) DLBCL. EZH2 expression had no impact on therapeutic efficacy in R-CHOP-treated patients. In conclusion, EZH2 seems to be upregulated by MYC, to rely on TP53 alterations, and is associated with high proliferative tumors in DLBCL, which might be dependent on GC or nGC subclassifications. Furthermore, it is not a therapeutic efficacy marker to R-CHOP in our series.     

Survivin and laryngeal carcinoma prognosis: nuclear localization and expression of splice variants

Marioni G, Agostini M, Bedin C, Blandamura S, Stellini E, Favero G, Lionello M, Giacomelli L, Burti S, D’Angelo E, Nitti D, Staffieri A & De Filippis C
(2012) Histopathology  61, 247–256 Survivin and laryngeal carcinoma prognosis: nuclear localization and expression of splice variants Aims: Aberrant survivin expression in cancer cells has been associated with tumour progression, radiation/drug resistance and shorter patient survival. The aim of the present study was to investigate survivin expression in laryngeal carcinoma (LSCC) tissue and – for the first time at this site – the expression of survivin splice variants. P53 was also studied. Methods and results: Survivin and p53 expression was determined immunohistochemically in 86 consecutive patients operated for LSCC. Survivin mRNA expression was assessed by quantitative real‐time polymerase chain reaction (PCR). Hot‐spot mutations in exons 5, 6, 7 and 8 of the TP53 gene were studied by sequencing analysis. A nuclear localization for survivin predominated. There was a significant association between a higher nuclear survivin expression and LSCC recurrence (P = 0.046). Disease‐free survival (DFS) for LSCC patients with a nuclear survivin expression >7.0% was shorter than in cases whose expression was ≤7.0% (P = 0.05). Wild‐type survivin correlated significantly with nuclear survivin expression (P = 0.02). p53 expression was associated with the co‐expression of wild‐type survivin and survivin‐2B (P = 0.01). Conclusions: Nuclear expression of survivin appears to influence LSCC aggressiveness, a higher nuclear survivin expression correlating with a higher recurrence rate and a shorter DFS. Wild‐type survivin was the most frequently detected splice variant in LSCC tissues.     

Abundant immunohistochemical expression of dopamine D2 receptor and p53 protein in meningiomas: follow-up,relation to gender,age, tumor grade,and recurrence

Meningiomas are common, usually benign tumors, with a high postoperative recurrence rate. However, the genesis and development of these tumors remain controversial. We aimed to investigate the presence and implications of a mutated p53 protein and dopamine D₂ receptor in a representative series of meningiomas and to correlate these findings with age, gender, tumor grade, and recurrence. Tumor tissue samples of 157 patients diagnosed with meningioma (37 males and 120 females, mean age 53.6±14.3 years) who underwent surgical resection between 2003 and 2012 at our institution were immunohistochemically evaluated for the presence of p53 protein and dopamine D₂ receptor and were followed-up to analyze tumor recurrence or regrowth. Tumors were classified as grades I (n=141, 89.8%), II (n=13, 8.3%), or grade III (n=3, 1.9%). Dopamine D₂ receptor and p53 protein expression were positive in 93.6% and 49.7% of the cases, respectively. Neither of the markers showed significant expression differences among different tumor grades or recurrence or regrowth statuses. Our findings highlight the potential role of p53 protein in meningioma development and/or progression. The high positivity of dopamine D₂ receptor observed in this study warrants further investigation of the therapeutic potential of dopamine agonists in the evolution of meningiomas.     

Circular RNA ITCH mediates H2O2‐induced myocardial cell apoptosis by targeting miR‐17‐5p via wnt/β‐catenin signalling pathway

Cardiovascular disease is a severe threat health worldwide, and circRNAs have been shown to be correlated with the development of cardiovascular disease. Expression of circ‐ITCH and miR‐17a‐5p was evaluated by RT‐qPCR. Cell viability was measured using CCK‐8. Flow cytometry was applied to measure apoptosis rate. Binding between miR‐17‐5p and circ‐ITCH was detected via luciferase reporter assays. Levels of ATP in cells were examined with ATP testing. Western blot was used to evaluate apoptosis‐related proteins and proteins in Wnt/β‐catenin signalling pathway. H₂O₂ induced apoptosis of H9c2 cells and lowered cell viability as well as ATP levels and circ‐ITCH expression. After overexpression, circ‐ITCH enhanced cell viability and ATP concentration. Meanwhile, apoptosis was inhibited. MiR‐17‐5p was the target of circ‐ITCH as evidenced by luciferase report assays, with higher expression in H₂O₂‐induced H9c2 cells. Knockdown of miR‐17‐5p could promote cell viability and level of ATP and curb apoptosis and p53 and PARP expression. Moreover, overexpressed miR‐17‐5p could reverse the function of upregulated circ‐ITCH. Wnt3a, Wnt5a and β‐catenin in Wnt/β‐catenin signalling pathway were increased after H₂O₂ induction. Suppression of Wnt/β‐catenin signalling pathway could initiate the process of injury in H9c2 cells. Circ‐ITCH could protect myocardial cells from injuries caused by H₂O₂ by suppressing apoptosis while miR‐17‐5p played a reverse role, which could upregulate apoptosis and inhibit cell viability via Wnt/β‐catenin signalling pathway.     

Expression of E-cadherin and its relation to the p53 protein status in human breast carcinomas

 In breast carcinomas the TP53 gene is altered in 10–30% of cases. Alteration of the gene may lead to a general genomic instability, detected as deletions and/or amplifications at the gene level, and as altered expression at the mRNA and protein level. We have demonstrated a strong association between down-regulation of E-cadherin protein expression and alterations of the p53 protein, detected as TP53 gene mutation and/or protein accumulation in tumour samples from 210 patients with breast carcinomas (P <0.001). Investigation of allelic imbalance using microsatellite markers located near the E-cadherin locus was also performed. A higher frequency of loss of heterozygosity in the microsatellite marker closest to the E-cadherin locus was observed in samples with down-regulation of E-cadherin protein expression. A higher frequency of down-regulation of the E-cadherin protein expression was found in invasive lobular carcinomas than in invasive ductal carcinomas, although this difference was of borderline significant (P=0.084). Cases in the present series were also immunostained for c-erbB-2 protein overexpression. A significant association between p53 protein accumulation and cerbB-2 protein overexpression was seen (P=0.036). The results of the present study indicate that p53 protein may play a role in regulation of E-cadherin protein expression. Received: 29 May 1997)Accepted: 10 June 1997     

Prognostic significance of p53 gene mutations and p53 protein expression in synovial sarcomas

Alterations to p53 seem to be of prognostic significance in soft tissue sarcomas, but their significance for synovial sarcomas has not been studied. We analysed 34 synovial sarcomas in 19 patients for p53 alterations (p53 gene mutations + p53 immunopositivity) and examined this factor for its prognostic value in a group of 15 primary tumours. DNA was prepared from paraffin-embedded tumour material by a modified proteinase K/phenol/chloroform extraction. p53 gene mutations of exons 5–8 were analysed by the PCR-SSCP-sequencing method. p53 protein expression was evaluated by immunohistochemistry using the murine monoclonal antibody DO1. We found two missense mutations (5.9%) and ten p53 immunopositive cases (29.4%). Both tumours with p53 mutations showed p53 protein expression. There was no significant correlation between p53 alteration and histological subtype, age, sex, or tumour size. The 5-year survival rate was 24.1%. Overall survival was significantly reduced in patients having synovial sarcomas with p53 alterations (P<0.001). In the multivariate Cox’s analysis, only p53 alterations (P=0.032) and tumour size (P=0.023) emerged as independent prognostic factors. We suggest that p53 alterations may be a useful prognostic indicator in synovial sarcomas, allowing rational clinical treatment and follow-up. Received: 13 April 1999 / Accepted:18 May 1999     

TP53 alterations in relation to the cell cycle-associated proteins p21, cyclin D1, CDK4, RB,MDM2, and EGFR in cancers of the uterine corpus

In the present study, TP53 alterations have been analysed and compared with the expression of the proteins p21, cyclin D1, cdk4, RB, EGFR, and MDM2 in 53 cancers of the uterine corpus. TP53 gene mutations analysed by CDGE/DGGE and direct sequencing showed a TP53 gene mutation in 18 per cent of the cases. TP53 gene mutations were not significantly related to overexpression or down-regulation of any of the proteins. Immunohistochemically, there was an increased protein level of TP53 in 77 per cent, p21 in 36 per cent, cyclin D1 in 45 per cent, cdk4 in 77 per cent, EGFR in 8 per cent, and MDM2 in 32 per cent of the cases. Expression of RB protein was normal in all cancers. Significant association of protein expression was seen between TP53 and MDM2 (p = 0·005) and p21 and MDM2 (p = 0·001). Furthermore, there may be an association between TP53 and p21 (p = 0·038) and cyclin D1 and cdk4 (p = 0·045). The results revealed increased levels of TP53 protein in all MDM2-positive cases that did not show TP53 mutations, indicating TP53 protein stabilization and inactivation by complex formation with MDM2. In summary, the high number of cases showing an increased level of TP53 and cdk4 proteins suggests that these proteins play an important role in the neoplastic process in cancers of the uterine corpus. Copyright © 1999 John Wiley & Sons, Ltd.     

Distinctive patterns of p53 protein expression and microsatellite instability in human colorectal cancer

Although evidence suggests an inverse relationship between microsatellite instability and p53 alterations in colorectal cancer, no study has thoroughly examined the use of p53 immunohistochemistry in phenotyping colorectal cancers. We investigated the value of p53 immunohistochemistry in microsatellite instability–positive colorectal cancers prescreening and attempted to clarify the relationship between DNA mismatch repair system and p53 pathway. In a series of 104 consecutive colorectal cancers, we performed p53 immunohistochemistry, TP53 mutational analysis, DNA mismatch repair system efficiency evaluation (DNA mismatch repair system immunohistochemistry, microsatellite instability status, MLH1/MSH2 germ line, and BRAF, murine double minute 2, and p21 immunohistochemistry. Microsatellite instability high was observed in 25 of 104 colorectal cancers, with DNA mismatch repair system protein loss (24/25) and germ line (8/25) or BRAF mutations (8/25). p53 immunohistochemistry revealed 3 distinct patterns of expression: complete negative immunostaining associated with truncating TP53 mutations (P < .0001), diffuse overexpression associated with missense TP53 mutations (P < .0001), and restricted overexpression characterized by a limited number of homogenously scattered strongly positive tumor cells in 36.5% of colorectal cancers. This latest pattern was associated with wild-type TP53 and microsatellite instability high colorectal cancers (P < .0001) including all Lynch tumors (8/8), but its presence among 22% of DNA mismatch repair system–competent colorectal cancers decreased its positive predictive value (55.2% [95% confidence interval, 45%-65%]). It was also correlated with murine double minute 2 overexpression (P < .0001) and inversely with p21 loss (P = .0002), independently of microsatellite instability status. In conclusion, a restricted pattern of p53 overexpression is preferentially associated with microsatellite instability high phenotype and could, therefore, be of clinical use as signal for microsatellite instability analysis in a large-scale tumor screening. Its association with concomitant murine double minute 2 overexpression suggests an alternative mechanism of p53 pathway deregulation.     

Involvement of α‐ and β‐catenins and E‐cadherin in the development of mammary phyllodes tumours

Tsang J Y S, Mendoza P, Lam C C F, Yu A M C, Putti T C, Karim R Z, Scolyer R A, Lee C S, Tan P H & Tse G M
(2012) Histopathology  61, 667–674 Involvement of α‐ and β‐catenins and E‐cadherin in the development of mammary phyllodes tumours Aims: Phyllodes tumours (PT) are rare but clinically important fibroepithelial tumours of the breast. β‐Catenin, a key component in Wnt signalling, has been shown to be important in the development of PT. It also functions as a component of the cadherin complex, which may therefore be implicated in PT pathogenesis. By assessing stromal α‐catenin, β‐catenin and E‐cadherin expression in 158 PT cases using immunohistochemistry and examining associations with clinicopathological features, we aimed to determine the role of these proteins in PT pathogenesis. Methods and results: Cytoplasmic β‐catenin correlated with α‐catenin expression. A significantly higher expression of both markers was observed in borderline than in benign PT (P = 0.003 and <0.001, respectively), but a lower level was found in malignant PT. Cytoplasmic E‐cadherin expression was significantly higher in borderline and malignant than in benign PT (P = 0.001 and 0.012, respectively), but was not correlated with other markers. Both E‐cadherin and α‐catenin showed stronger correlations with histological parameters than β‐catenin. α‐Catenin showed a significant correlation with recurrence (P = 0.005 and 0.016, respectively). Conclusions: α‐ and β‐catenins may be important in the early stages of PT development, while E‐cadherin may be required for malignant development. The correlation of α‐catenin expression with tumour recurrence may be relevant in predicting PT behaviour.     

Malignant transformation of mature cystic teratoma to squamous cell carcinoma involves altered expression of p53‐ and p16/Rb‐dependent cell cycle regulator proteins

Ovarian mature cystic teratomas (MCT) uncommonly undergo malignant transformation to squamous cell carcinoma (SCC). While alterations in the p53 tumor suppressor gene and protein have been shown, few studies have analyzed other molecular changes leading to this malignant conversion. The purpose of the present study was to investigate 21 samples of SCC arising in MCT for altered expression in known p53‐ and p16/Rb‐dependent cell cycle regulatory proteins, and the association between their expression and cellular proliferation and histological features. Overexpression of the p53 protein was observed in 14 SCC (67%), while four (19%) had point mutations in the p53 gene. Reduced expression of the p16 protein was observed in 18 SCC (86%), while p16 gene alterations (hypermethylation (29%) and point mutation (33%)) were found in 11 (52%). Furthermore, a statistically significant correlation was observed between p53 and Rb overexpression (P = 0.0010), and the overexpression of both p53 and Rb was respectively significantly correlated with increased cellular proliferation. The results indicate that alterations in both the p53 and p16‐Rb pathways are associated with SCC arising in MCT.