Upregulation of PTTG1 is associated with poor prognosis in prostate cancer

Pituitary tumor-transforming gene 1 (PTTG1) is a regulator of chromosome stability. PTTG1 overexpression had been associated with tumor aggressiveness in several cancer types. To examine its prognostic utility in prostate cancer, a tissue microarray including 12 427 tumors with clinical and molecular data was analyzed by immunohistochemistry. PTTG1 immunostaining was largely absent in normal prostate epithelial cells. In cancers, staining was considered weak in 5.4%, moderate in 5.6% and strong in 0.8%. Strong staining was linked to advanced pT stage, high classical and quantitative Gleason grade, high Ki67-labeling index (all P < 0.0001) and lymph node metastasis (P = 0.0083). The prognostic impact of PTTG1 expression was independent of established preoperative and postoperative prognostic features. Comparison with molecular features revealed that PTTG1 upregulation was associated with nine of 12 common genomic deletions (P < 0.05), p53 alterations and high androgen receptor levels (P < 0.001 each), but was unrelated to the TMPRSS2:ERG fusion status. In conclusion, these data identify PTTG1 as a strong and independent prognostic feature in prostate cancer. PTTG1 measurement, either alone or in combination with other biomarkers might be instrumental for determining prostate cancer aggressiveness.

PTTG1 regulated by miR-146a-3p promotes bladder cancer migration, invasion, metastasis and growth

Pituitary tumor-transforming gene 1 (PTTG1) is identified as an oncogene, and overexpresses in many tumors. However, the role of PTTG1 in bladder cancer (BC) hasn't yet been characterized well. In this study, we showed the expression of PTTG1 mRNA and protein were both significantly increased in BC tissues and cells. The PTTG1 protein levels were positive correlated with increased tumor size, tumor–node–metastasis (TNM) stage, lymphatic invasion and distant metastasis of BC. PTTG1 knockdown dramatically suppressed the migration, invasion, metastasis and growth, and induced senescence and cell-cycle arrest at G0/G1 phase of BC cells. We further identified PTTG1 was the direct target of miR-146a-3p through using target prediction algorithms and luciferase reporter assay. miR-146a-3p was low expressed and negatively correlated with PTTG1 levels in BC tissues and cells. miR-146a-3p overexpression inhibited migration, invasion, metastasis and growth, and induced senescence of BC cells. Rescue experiment suggested ectopic expression of miR-146a-3p and PTTG1 suppressed migration, invasion and induced cell cycle arrest and senescence of BC cells compared to PTTG1 overexpression, confirming miR-146a-3p inhibited BC progression by targeting PTTG1. In summary, our study found miR-146a-3p/PTTG1 axis regulated BC migration, invasion, metastasis and growth, and might be a targets for BC therapy.

Interleukin-6/signal transducer and activator of transcription 3 promotes prostate cancer resistance to androgen deprivation therapy via regulating pituitary tumor transforming gene 1 expression

Prostate cancer can progress from androgen dependence to androgen deprivation resistance with some unknown mechanisms. The current study aims to explore the possible role of pituitary tumor transforming gene1 (PTTG1) in castration-resistant prostate cancer (CRPC). Initially, we found that PTTG1 expression was significantly increased in androgen-independent prostate cancer cell lines PC3, DU145 and CRPC specimens compared with that in androgen-dependent prostate cancer cell line LNCaP and initial prostate cancer specimens. PTTG1 overexpression significantly enhanced the cell survival rate, clonality and tumorigenicity in LNCaP cells upon androgen-deprivation therapy (ADT). While knockdown of PTTG1 expression significantly elevated the sensitivity of DU145 cells to ADT. The effects of PTTG1 overexpression on LNCaP cells may be ascribed to the induced EMT and increased CD44⁺ CD24^- cancer stem cell population. Furthermore, we detected that PTTG1 expression was regulated by interleukin-6 via activated signal transducer and activator of transcription 3 (STAT3) directly binding to the region -500 to +1 of PTTG1 promoter in LNCaP cells. In conclusion, our results elucidate that interleukin-6/STAT3 activation can increase PTTG1 expression and, consequently, promote the resistance to ADT in CRPC by inducing EMT and increasing the cancer stem cell population, suggesting that PTTG1 may be a novel therapeutic target for CRPC.

The clinical value and biological function of PTTG1 in colorectal cancer

Pituitary tumor transforming gene-1 (PTTG1) has been suggested to serve as an oncogene in several types of human tumors, but little is known about the biological function of PTTG1 in colorectal cancer. PTTG1 mRNA and protein expressions in colorectal cancer tissues and cell lines were measured by qRT-PCR, western blot or immunohistochemistry. The association between PTTG1 protein expression and clinicopathological features was analyzed. The function of PTTG1 on colorectal cancer cell proliferation and metastasis were explored through MTT, colony formation, migration and invasion assays. In our results, PTTG1 mRNA and protein expressions were increased in colorectal cancer tissues and cell lines compared with normal colonic tissues and colon epithelial cell line. PTTG1 overexpression positively associated with clinical stage, T classification, N classification, M classification and differentiation. The univariate and multivariate analyses suggested PTTG1 overexpression was an independent poor prognostic factor for colorectal cancer patients. The in vitro experiments showed knocking down PTTG1 inhibited colorectal cancer growth and metastasis. In conclusion, PTTG1 is an independent prognostic factor and acts as an oncogene in colorectal cancer.

Pituitary tumor transforming gene-1 in non-small cell lung cancer: Clinicopathological and immunohistochemical analysis

Pituitary tumor transforming gene-1 (PTTG1) is a novel oncogene and overexpressed in a wide variety of human cancers. However, the clinical and prognostic significance of PTTG1 in non-small cell lung cancer (NSCLC) is still unknown. The expression status of PTTG1 in NSCLC at the publicly available GEO databases (GSE19804) was observed. The mRNA and protein expression of PTTG1 in NSCLC tissues and cell lines was detected by qRT-PCR and Western blot, and the association between PTTG1 expression and clinicopathological factors was analyzed by immunohistochemistry. In our Results, PTTG1 was one of genes overexpressed in NCSLC samples compared with paired adjacent normal lung samples in microarray data (GSE19804). PTTG1 mRNA and protein expressions were increased in NSCLC tissues and cell lines. PTTG1 protein expression was correlated with malignant status and poor prognosis of NSCLC patients. In conclusion, PTTG1 is correlated with NSCLC progression and as an independent poor prognostic factor in NSCLC patients.

MiRNA-494 inhibits metastasis of cervical cancer through Pttg1

Many cervical cancer (CC) patients experience early cancer metastasis, resulting in poor therapeutic outcome after resection of primary cancer. Hence, there is a compelling requirement for understanding of the molecular mechanisms underlying the invasiveness control of CC. Pituitary tumor-transforming gene 1 (Pttg1) has been recently reported to promote cancer cell growth and metastasis in a number of various tumors. However, its regulation by microRNAs (miRNAs) as well as its role in CC have not been clarified. Here, we reported significantly higher levels of Pttg1 and significantly lower levels of miR-494 in the resected CC tissue, compared with the adjacent normal cervical tissue from the same patient. Interestingly, Pttg1 levels inversely correlated with miR-494 levels. In vitro, Pttg1 levels determined CC cell invasiveness and were inhibited by miR-494 levels. However, miR-494 levels were not affected by Pttg1 levels. Furthermore, miR-494 inhibited Pttg1 expression in CC cells, through directly binding and inhibition on 3'-UTR of Pttg1 mRNA. Together, our data suggest that Pttg1 may increase CC cell metastasis, which is negatively regulated by miR-494. Our work thus highlights a novel molecular regulatory machinery in metastasis of CC.

Knockdown of PTTG1 inhibits the growth and invasion of lung adenocarcinoma cells through regulation of TGFB1/SMAD3 signaling

Increased expression of pituitary tumor-transforming gene 1 (PTTG1) is expressed in many tumors and regulates tumor growth and progression. However, the precise function of PTTG1 in the tumorigenesis of lung adenocarcinoma (LAC) is not defined yet. Here, we examined the expression of PTTG1 in human LAC tissues by immunohistochemical assay using a tissue microarray procedure. A loss-of-function experiment was carried out to investigate the effects of lentiviral vector-mediated PTTG1 shRNA (shPTTG1) on cell growth and invasive potential in LAC cell lines (A549 and LETPα-2), assessed by MTT and Transwell assays. As a consequence, we found that the expression of PTTG1 protein was markedly upregulated in LAC tissues compared with the adjacent non-cancerous tissues (ANCT) (54.0% vs. 28.0%, P = 0.008), and was positively associated with the lymphatic invasion of the tumor ( P = 0.01). Moreover, knockdown of PTTG1 expression inhibited tumor proliferation and invasion of LAC cells, companied by the decreased expression of CyclinD1 and MMP-2 and increased expression of p-TGFβ1 and p-SMAD3. Collectively, our findings indicate that high expression of PTTG1 is correlated with the tumor metastasis of LAC patients, and knockdown of PTTG1 suppresses the growth and invasion of LAC cells through upregulation of the TGFβ1/SMAD3 signaling, suggesting that PTTG1 may be a potential target for developing an effective immunotherapeutic strategy for LAC.