Prognostic impact of RITA expression in patients with anal squamous cell carcinoma treated with chemoradiotherapy

RITA1 drives the growth of bladder cancer cells by recruiting TRIM25 to facilitate the proteasomal degradation of RBPJ

Bladder cancer (BC) is one of the most prevalent malignancies worldwide, but it lacks effective targeted therapy due to its elusive molecular mechanism. Therefore, it is important to further investigate the molecular mechanisms that mediate BC progression. By performing a tumor tissue–based gene microarray and shRNA library screening, we found that recombination signal binding protein for immunoglobulin kappa J region (RBPJ) interacting and tubulin associated 1 (RITA1) is crucial for the growth of BC cells. Moreover, RITA1 is aberrantly highly expressed in BC tissues and is also correlated with poor prognosis in patients with BC. Mechanistically, we determined that RITA1 recruits tripartite motif containing 25 (TRIM25) to ubiquitinate RBPJ to accelerate its degradation via proteasome, which leads to the transcriptional inhibition of Notch1 downstream targets. Our results suggest that aberrant high expression of RITA1 drives the growth of BC cells via the RITA1/TRIM25/RBPJ axis and RITA1 may serve as a promising therapeutic target for BC.

Prognostic factors for patients with anal cancer treated with conformal radiotherapy-a systematic review

AIMS

Anal cancer is primarily treated using concurrent chemoradiotherapy (CRT), with conformal techniques such as intensity modulated radiotherapy (IMRT) and volumetric arc therapy (VMAT) now being the standard techniques utilised across the world. Despite this, there is still very limited consensus on prognostic factors for outcome following conformal CRT. This systematic review aims to evaluate the existing literature to identify prognostic factors for a variety of oncological outcomes in anal cancer, focusing on patients treated with curative intent using contemporary conformal radiotherapy techniques.

MATERIALS AND METHODS

A literature search was conducted using Medline and Embase to identify studies reporting on prognostic factors for survival and cancer-related outcomes after conformal CRT for anal cancer. The prognostic factors which were identified as significant in univariable and multivariable analysis, along with their respective factor effects (where available) were extracted. Only factors reported as prognostic in more than one study were included in the final results.

RESULTS

The results from 19 studies were analysed. In both univariable and multivariable analysis, N stage, T stage, and sex were found to be the most prevalent and reliable clinical prognostic factors for the majority of outcomes explored. Only a few biomarkers have been identified as prognostic by more than one study - pre-treatment biopsy HPV load, as well as the presence of leukocytosis, neutrophilia and anaemia at baseline measurement. The results also highlight the lack of studies with large cohorts exploring the prognostic significance of imaging factors.

CONCLUSION

Establishing a set of prognostic and potentially predictive factors for anal cancer outcomes can guide the risk stratification of patients, aiding the design of future clinical trials. Such trials will in turn provide us with greater insight into how to effectively treat this disease using a more personalised approach.

Functional Analysis of p21Cip1/CDKN1A and Its Family Members in Trophoblastic Cells of the Placenta and Its Roles in Preeclampsia

Preeclampsia (PE), a gestational hypertensive disease originating from the placenta, is characterized by an imbalance of various cellular processes. The cell cycle regulator p21^Cip1/CDKN1A (p21) and its family members p27 and p57 regulate signaling pathways fundamental to placental development. The aim of the present study was to enlighten the individual roles of these cell cycle regulators in placental development and their molecular involvement in the pathogenesis of PE. The expression and localization of p21, phospho-p21 (Thr-145), p27, and p57 was immunohistochemically analyzed in placental tissues from patients with early-onset PE, early-onset PE complicated by the HELLP (hemolysis, elevated liver enzymes and low platelet count) syndrome as well as late-onset PE compared to their corresponding control tissues from well-matched women undergoing caesarean sections. The gene level was evaluated using real-time quantitative PCR. We demonstrate that the delivery mode strongly influenced placental gene expression, especially for CDKN1A (p21) and CDKN1B (p27), which were significantly upregulated in response to labor. Cell cycle regulators were highly expressed in first trimester placentas and impacted by hypoxic conditions. In support of these observations, p21 protein was abundant in trophoblast organoids and hypoxia reduced its gene expression. Microarray analysis of the trophoblastic BeWo cell line depleted of p21 revealed various interesting candidate genes and signaling pathways for the fusion process. The level of p21 was reduced in fusing cytotrophoblasts in early-onset PE placentas and depletion of p21 led to reduced expression of fusion-related genes such as syncytin-2 and human chorionic gonadotropin (β-hCG), which adversely affected the fusion capability of trophoblastic cells. These data highlight that cell cycle regulators are important for the development of the placenta. Interfering with p21 influences multiple pathways related to the pathogenesis of PE.

RITA Is Expressed in Trophoblastic Cells and Is Involved in Differentiation Processes of the Placenta

Preeclampsia (PE) remains a leading cause of maternal and perinatal mortality and morbidity worldwide. Its pathogenesis has not been fully elucidated and no causal therapy is currently available. It is of clinical relevance to decipher novel molecular biomarkers. RITA (RBP-J (recombination signal binding protein J)-interacting and tubulin-associated protein) has been identified as a negative modulator of the Notch pathway and as a microtubule-associated protein important for cell migration and invasion. In the present work, we have systematically studied RITA’s expression in primary placental tissues from patients with early- and late-onset PE as well as in various trophoblastic cell lines. RITA is expressed in primary placental tissues throughout gestation, especially in proliferative villous cytotrophoblasts, in the terminally differentiated syncytiotrophoblast, and in migrating extravillous trophoblasts. RITA’s messenger RNA (mRNA) level is decreased in primary tissue samples from early-onset PE patients. The deficiency of RITA impairs the motility and invasion capacity of trophoblastic cell lines, and compromises the fusion ability of trophoblast-derived choriocarcinoma cells. These data suggest that RITA may play important roles in the development of the placenta and possibly in the pathogenesis of PE.

RITA modulates cell migration and invasion by affecting focal adhesion dynamics

RITA, the RBP-J interacting and tubulin-associated protein, has been reported to be related to tumor development, but the underlying mechanisms are not understood. Since RITA interacts with tubulin and coats microtubules of the cytoskeleton, we hypothesized that it is involved in cell motility. We show here that depletion of RITA reduces cell migration and invasion of diverse cancer cell lines and mouse embryonic fibroblasts. Cells depleted of RITA display stable focal adhesions (FA) with elevated active integrin, phosphorylated focal adhesion kinase, and paxillin. This is accompanied by enlarged size and disturbed turnover of FA. These cells also demonstrate increased polymerized tubulin. Interestingly, RITA is precipitated with the lipoma-preferred partner (LPP), which is critical in actin cytoskeleton remodeling and cell migration. Suppression of RITA results in reduced LPP and α-actinin at FA leading to compromised focal adhesion turnover and actin dynamics. This study identifies RITA as a novel crucial player in cell migration and invasion by affecting the turnover of FA through its interference with the dynamics of actin filaments and microtubules. Its deregulation may contribute to malignant progression.

Potential involvement of RITA in the activation of Aurora A at spindle poles during mitosis

The mitotic kinase Aurora A is crucial for various mitotic events. Its activation has been intensively investigated and is not yet completely understood. RITA, the RBP-J interacting and tubulin-associated protein, has been shown to modulate microtubule dynamics in mitosis. We asked if RITA could be related to the activation of Aurora A. We show here that RITA is colocalized with Aurora A and its activator TPX2 at spindle poles during mitosis. FLAG-RITA is precipitated with the complex of Aurora A, TPX2 and tubulin. Depletion of RITA increases exclusively active Aurora A and TPX2 at spindle poles in diverse cancer cell lines and in RITA knockout mouse embryonic fibroblasts. The enhanced active Aurora A, its substrate p-TACC3 and TPX2 are restored by adding back of RITA but not its Δtub mutant with an impaired tubulin-binding capability, indicating that RITA's role as Aurora A's modulator is mediated through its interaction with tubulin. Also, the mitotic failures in cells depleted of RITA are rescued by the inhibition of Aurora A. RITA itself does not directly interfere with the catalytic activity of Aurora A, instead, affects the microtubule binding of its activator TPX2. Moreover, Aurora A's activation correlates with microtubule stabilization induced by the microtubule stabilizer paclitaxel, implicating that stabilized microtubules caused by RITA depletion could also account for increased active Aurora A. Our data suggest a potential role for RITA in the activation of Aurora A at spindle poles by modulating the microtubule binding of TPX2 and the microtubule stability during mitosis.