Comprehensive mutational analysis and mRNA isoform quantification of TP63 in normal and neoplastic human prostate cells

LncRNA CTBP1-AS inhibits TP63-mediated activation of S100A14 during prostate cancer progression

Long noncoding RNAs (lncRNAs) have emerged as important molecules and potential new targets for human cancers. This study investigates the function of lncRNA CTBP1 antisense RNA (CTBP1-AS) in prostate cancer (PCa) and explores the entailed molecular mechanism. Aberrantly expressed genes potentially correlated with PCa progression were probed using integrated bioinformatics analyses. A cohort of 68 patients with PCa was included, and their tumor and para-cancerous tissues were collected. CTBP1-AS was highly expressed in PCa tissues and cells and associated with poor patient prognosis. By contrast, tumor protein p63 (TP63) and S100 calcium binding protein A14 (S100A14) were poorly expressed in the PCa tissues and cells. CTBP1-AS did not affect TP63 expression; however it blocked the TP63-mediated transcriptional activation of S100A14, thereby reducing its expression. CTBP1-AS silencing suppressed proliferation, apoptosis resistance, migration, invasion, and tumorigenicity of PCa cell lines, while its overexpression led to inverse results. The malignant phenotype of cells was further weakened by TP63 overexpression but restored following artificial S100A14 silencing. In conclusion, this study demonstrates that CTBP1-AS plays an oncogenic role in PCa by blocking TP63-mediated transcriptional activation of S100A14. This may provide insight into the management of PCa.

Immunomolecular Investigation of Human Papillomavirus Genotypes (16, 18) and P63 Expression in Patients with Malignant and Non-malignant Colorectal Tumors

Cancer of the colon (colorectal cancer, or CRC) is the third most frequent malignancy in the world and the fourth leading cause of cancer-related death. Recent research has focused on the link between high-risk human papillomavirus (HPV) infections and the onset/development of several different types of cancer in humans. As a result, scientists are now paying more attention to HPV and CRC. In a variety of malignant tumors, P63 is overexpressed. This includes non-Hodgkin lymphoma and breast carcinoma, as well as lung, bladder, and prostate cancers. However, in accordance with the existence of many P63 isoforms in malignant tumors, the actions of P63 in these malignancies remain a source of debate. P63 immunohistochemistry expression in CRC tissues is being investigated as a possible etiological link between high-risk HPV types and CRC. This retrospective study intended to investigate if there was an etiological link between high-risk HPV types and CRC. It has utilized 92 chosen formalin-fixed and paraffin-embedded tissue block samples. The collected samples were divided into 62 blocks of colorectal adenocarcinoma mass tissues and 30 non-malignant colorectal tissues used as a control group. Chromogenic in situ hybridization (CISH) was employed to discover HPV DNA16/18 in colorectal tissues. The overall proportion of positive HPV16/18 DNA- CISH detection in the mass CRC group was 44.4%, whereas HPV16/18 DNA was obtained at 80.0% in the non-malignant control group. The overall proportion of positive P63-ISH detection in the CRC group was also 70.4%, whereas P63 was 73.3% in the non-malignant control group. The link between HPV infection and P63 expression in CRC might point to the importance of these molecules in the progression of CRC.

Novel HOXD13 variants in syndactyly type 1b and type 1c, and a new spectrum of TP63-related disorders

Syndactyly is the most common limb defect depicting the bony and/or cutaneous fusion of digits. Syndactyly can be of various types depending on the digits involved in the fusion. To date, eight syndactyly-associated genes have been reported, of which HOXD13 and GJA1 have been explored in a few syndactyly but most of them have unknown underlying genetics. In the present study HOXD13, GJA1 and TP63 genes have been screened by resequencing in 24 unrelated sporadic cases with various syndactyly. The screening revealed two pathogenic HOXD13 variants, NM_000523:c.500 A > G [p.(Y167C)], and NM_000523:c.961 A > C [p.(T321P)] in syndactyly type 1b and type 1c, respectively. This is the first report to identify HOXD13 pathogenic variant in syndactyly type 1b and third report in syndactyly type 1c pathogenesis. Furthermore, this study also reports a TP63 pathogenic variant, NM_003722:c.953 G > A [p.(R318H)] in Ectrodactyly and Cleft lip and palate (ECLP). In conclusion, the current study expands the clinical spectrum of HOXD13 and TP63-related disorders.

EAF2 and p53 Co-Regulate STAT3 Activation in Prostate Cancer

The tumor suppressor genes EAF2 and p53 are frequently dysregulated in prostate cancers. Recently, we reported that concurrent p53 nuclear staining and EAF2 downregulation were associated with high Gleason score. Combined loss of EAF2 and p53 in a murine model induced prostate tumors, and concurrent knockdown of EAF2 and p53 in prostate cancer cells enhanced proliferation and migration, further suggesting that EAF2 and p53 could functionally interact in the suppression of prostate tumorigenesis. Here, RNA-seq analyses identified differentially regulated genes in response to concurrent knockdown of p53 and EAF2. Several of these genes were associated with the STAT3 signaling pathway, and this was verified by significantly increased p-STAT3 immunostaining in the Eaf2^-/-p53^-/- mouse prostate. STAT3 knockdown abrogated the stimulation of C4-2 cell proliferation by concurrent knockdown of EAF2 and p53. Furthermore, immunostaining of p-STAT3 was increased in human prostate cancer specimens with EAF2 downregulation and/or p53 nuclear staining. Our findings suggest that simultaneous inactivation of EAF2 and p53 can act to activate STAT3 and drive prostate tumorigenesis.

p63 expression is a prognostic factor in colorectal cancer

p63 is highly expressed in some malignant tumors and is associated with tumorigenesis, invasion and metastasis. The aim of our study was to evaluate the clinical significance of p63 in colorectal cancer (CRC). p63 expression was detected by immunohistochemistry in 66 CRC patients. Correlations between p63 expression and clinicopathological factors, progression-free survival (PFS) and overall survival (OS) were analyzed. Among the 66 CRC cases, 31 cases (47%) exhibited a high score of p63 expression, while 35 cases (53%) were marked with a low score. The p63 level correlated with peritumoral deposits (p=0.021). The 5-year OS rates in the low p63 score and high p63 score groups were, respectively, 49% and 74% (p<0.001). The 5-year PFS rates in the low p63 score and high p63 score groups were, respectively, 44% and 71% (p<0.001). Univariate analysis revealed that p63 expression was correlated with OS and PFS. Multivariate analysis suggested that p63 expression was an independent prognostic factor for OS (p=0.035). In conclusion, p63 was negatively correlated with peritumoral deposits and positively associated with OS and PFS in CRC. The data suggest that p63 is a potential prognostic factor for CRC.

ΔNp63α Transcriptionally Regulates the Expression of CTEN That Is Associated with Prostate Cell Adhesion

p63 is a member of the p53 transcription factor family and a linchpin of epithelial development and homeostasis. p63 drives the expression of many target genes involved in cell survival, adhesion, migration and cancer. In this study, we identify C-terminal tensin-like (CTEN) molecule as a downstream target of ΔNp63α, the predominant p63 isoform expressed in epithelium. CTEN belongs to the tensin family and is mainly localized to focal adhesions, which mediate many biological events such as cell adhesion, migration, proliferation and gene expression. Our study demonstrate that ΔNp63 and CTEN are both highly expressed in normal prostate epithelial cells and are down-regulated in prostate cancer. In addition, reduced expression of CTEN and ΔNp63 is correlated with prostate cancer progression from primary tumors to metastatic lesions. Silencing of ΔNp63 leads to decreased mRNA and protein levels of CTEN. ΔNp63α induces transcriptional activity of the CTEN promoter and a 140-bp fragment upstream of the transcription initiation site is the minimal promoter region required for activation. A putative binding site for p63 is located between -61 and -36 within the CTEN promoter and mutations of the critical nucleotides in this region abolish ΔNp63α-induced promoter activity. The direct interaction of ΔNp63α with the CTEN promoter was demonstrated using a chromatin immunoprecipitation (ChIP) assay. Moreover, impaired cell adhesion caused by ΔNp63α depletion is rescued by over-expression of CTEN, suggesting that CTEN is a downstream effector of ΔNp63α-mediated cell adhesion. In summary, our findings demonstrate that ΔNp63α functions as a trans-activation factor of CTEN promoter and regulates cell adhesion through modulating CTEN. Our study further contributes to the potential regulatory mechanisms of CTEN in prostate cancer progression.

Prostate adenocarcinomas aberrantly expressing p63 are molecularly distinct from usual-type prostatic adenocarcinomas

We have described a rare group of prostate adenocarcinomas that show aberrant expression of p63, a protein strongly expressed in prostatic basal cells and absent from usual-type acinar prostate cancers. The partial basal-like immunophenotype of these tumors is intriguing in light of the persistent debate surrounding the cell-of-origin for prostate cancer; however, their molecular phenotype is unknown. We collected 37 of these tumors on radical prostatectomy and biopsy and assessed subsets for a diverse panel of molecular markers. The majority of p63-expressing tumors were positive for the ΔNp63 isoform (6/7) by immunofluorescence and p63 mRNA (7/8) by chromogenic in situ hybridization. Despite p63 positivity, these tumors uniformly expressed luminal-type cytokeratin proteins such as CK18 (13/13), CK8 (8/8), and markers of androgen axis signaling commonly seen in luminal cells, including androgen receptor (10/11), NKX3.1 (8/8), and prostein (12/13). Conversely, basal cytokeratins such as CK14 and CK15 were negative in all cases (0/8) and CK5/6 was weakly and focally positive in 36% (4/11) of cases. Pluripotency markers including β-catenin, Oct4, and c-kit were negative in p63-expressing tumors (0/11). Despite nearly universal expression of androgen receptor and downstream androgen signaling targets, p63-expressing tumors lacked ERG rearrangements by fluorescence in situ hybridization (0/14) and ERG protein expression (0/37). No tumors expressed SPINK1 or showed PTEN protein loss (0/19). Surprisingly, 74% (14/19) of p63-expressing tumors expressed GSTP1 protein at least focally, and 33% (2/6) entirely lacked GSTP1 CpG island hypermethylation by bisulfite sequencing. In contrast to usual prostatic adenocarcinomas, prostate tumors with p63 expression show a mixed luminal/basal immunophenotype, uniformly lack ERG gene rearrangement, and frequently express GSTP1. These data strongly suggest that p63-expressing prostate tumors represent a molecularly distinct subclass and further study of this rare tumor type may yield important insights into the role of p63 in prostatic biology and the prostate cancer cell-of-origin.

p63 attenuates epithelial to mesenchymal potential in an experimental prostate cell model

The transcription factor p63 is central for epithelial homeostasis and development. In our model of epithelial to mesenchymal transition (EMT) in human prostate cells, p63 was one of the most down-regulated transcription factors during EMT. We therefore investigated the role of p63 in EMT. Over-expression of the predominant epithelial isoform ΔNp63α in mesenchymal type cells of the model led to gain of several epithelial characteristics without resulting in a complete mesenchymal to epithelial transition (MET). This was corroborated by a reciprocal effect when p63 was knocked down in epithelial EP156T cells. Global gene expression analyses showed that ΔNp63α induced gene modules involved in both cell-to-cell and cell-to-extracellular-matrix junctions in mesenchymal type cells. Genome-wide analysis of p63 binding sites using ChIP-seq analyses confirmed binding of p63 to regulatory areas of genes associated with cell adhesion in prostate epithelial cells. DH1 and ZEB1 are two elemental factors in the control of EMT. Over-expression and knock-down of these factors, respectively, were not sufficient alone or in combination with ΔNp63α to reverse completely the mesenchymal phenotype. The partial reversion of epithelial to mesenchymal transition might reflect the ability of ΔNp63α, as a key co-ordinator of several epithelial gene expression modules, to reduce epithelial to mesenchymal plasticity (EMP). The utility of ΔNp63α expression and the potential of reduced EMP in order to counteract metastasis warrant further investigation.

p53 Family: Role of Protein Isoforms in Human Cancer

TP53, TP63, and TP73 genes comprise the p53 family. Each gene produces protein isoforms through multiple mechanisms including extensive alternative mRNA splicing. Accumulating evidence shows that these isoforms play a critical role in the regulation of many biological processes in normal cells. Their abnormal expression contributes to tumorigenesis and has a profound effect on tumor response to curative therapy. This paper is an overview of isoform diversity in the p53 family and its role in cancer.

p63 is a suppressor of tumorigenesis and metastasis interacting with mutant p53

p53 mutations, occurring in two-thirds of all human cancers, confer a gain of function phenotype, including the ability to form metastasis, the determining feature in the prognosis of most human cancer. This effect seems mediated at least partially by its ability to physically interact with p63, thus affecting a cell invasion pathway, and accordingly, p63 is deregulated in human cancers. In addition, p63, as an 'epithelial organizer', directly impinges on epidermal mesenchimal transition, stemness, senescence, cell death and cell cycle arrest, all determinant in cancer, and thus p63 affects chemosensitivity and chemoresistance. This demonstrates an important role for p63 in cancer development and its progression, and the aim of this review is to set this new evidence that links p63 to metastasis within the context of the long conserved other functions of p63.

Role of p63 in cancer development

Since their initial identification p53 homologues p63 and p73 have been expected to play a role in cancer development due to their close homology to p53, notoriously one of the most mutated genes in cancer. However soon after their discovery the awareness that these genes were rarely mutated in cancer seemed to indicate that they did not play a role in its development. However a large number of data collected in the following years indicated that altered expression rather than mutation could be found in different neoplasia and play a role in its biology. In particular p63 due to its fundamental role in epithelial development seems to play a role in a number of tumors of epithelial origin. In this review we summarize some of the evidence linking p63 to carcinogenesis.

Tissue-specific regulatory regions of the PTH gene localized by novel chromosome 11 rearrangement breakpoints in a parathyroid adenoma

Parathyroid adenomas can contain clonal rearrangements of chromosome 11 that activate the cyclin D1 oncogene through juxtaposition with the PTH gene. Here we describe such a chromosomal rearrangement whose novel features provide clues to locating elusive cis-regulatory elements in the PTH gene and also expand the physical spectrum of pathogenetic breakpoints in the cyclin D1 gene region. Southern blot analyses of the parathyroid adenoma revealed rearrangement in the PTH gene locus. Analysis of rearranged DNA clones that contained the breakpoint, obtained by screening a tumor genomic library, pinpointed the breakpoint in the PTH locus 3.3 kb upstream of the first exon. Accordingly, highly conserved distal elements of the PTH 5' regulatory region were rearranged at the breakpoint approximately 450 kb upstream of the cyclin D1 oncogene, resulting in overexpression of cyclin D1 mRNA. Thus, PTH-cyclin D1 gene rearrangement breakpoints in parathyroid tumors can be located far from those previously recognized. In addition to expanding the molecular spectrum of pathogenetic chromosomal lesions in this disease, features of this specific rearrangement reinforce the existence of one or more novel cis-enhancer/regulatory elements for PTH gene expression and narrow their location to a 1.7-kb DNA segment in the distal PTH promoter.

A case of prostatic adenocarcinoma with aberrant p63 expression: presentation with detailed immunohistochemical study and FISH analysis

Prostate carcinomas showing aberrant diffuse-nuclear p63 expression are extremely rare, and there is only 1 article in the literature reporting a series of 21 such cases. We document an additional case of p63-positive prostatic adenocarcinoma in a 60-year-old man, whose diagnosis was difficult. The patient was found to have an elevated prostate-specific antigen (PSA) level at a general health check-up and was referred to the hospital. His serum PSA was 4.2 ng/mL. Digital rectal examination and transrectal ultrasonography did not reveal a lesion. Transrectal needle biopsy of the prostate detected atypical, small prostatic glands suspected for adenocarcinoma at 2 cores. However immunohistochemistry showed nuclear p63 expression in the suspicious glands. Repeat biopsy revealed only high-grade prostatic intraepithelial neoplasia. In the third transrectal biopsy, finding of the same atypical glands showing perineural invasion facilitated the diagnosis of malignancy. The patient underwent a radical prostatectomy. Five different small tumor foci were seen in the prostate after pathological evaluation, one of which was p63 positive and the others p63 negative. The largest of the classic p63-negative tumors showed a TMPRSS2-ERG translocation by fluorescent in situ hybridization while the p63-positive tumor did not. The authors submit that this subtype (p63-positive prostate adenocarcinoma) should be listed among the recognized rare variants of prostatic adenocarcinoma.

CD133, Trop-2 and alpha2beta1 integrin surface receptors as markers of putative human prostate cancer stem cells

Cancer stem cells (CSCs) play a key role in initiation and development of cancer and are attractive targets for therapy. The identification of CSC surface receptors to be used as therapeutic targets in vivo remains a difficult task. In this study, we assessed the expression pattern of three surface receptors: CD133, Trop-2 and alpha2beta1 integrin in human prostate cancer in order to identify CSC-niches. CD133 was found to be expressed in small clusters of cells localized in focal areas of benign as well as malignant lesions, suggesting that this protein is a bona fide marker of the prostate stem/progenitor compartment. Trop-2 was localized in both basal and luminal layers of benign glands and was highly expressed in malignant lesions. Moreover, isolated cells in benign and malignant areas were found to co-express both CD133 and Trop-2. alpha2beta1 integrin was expressed in the prostatic epithelium as well as in the surrounding stroma, limiting its utility as a marker of CSCs. In summary, we demonstrate that the combination of CD133 and Trop-2 is useful to mark putative CSC-containing compartments in human prostate.