The Pim-1 kinase stimulates maturation of TCRbeta-deficient T cell progenitors: implications for the mechanism of Pim-1 action

Prostate cancer immunotherapy: Improving clinical outcomes with a multi-pronged approach

Cancer immunotherapy has gained traction in recent years owing to remarkable tumor clearance in some patients. Despite the notable success of immune checkpoint blockade (ICB) in multiple malignancies, engagement of the immune system for targeted prostate cancer (PCa) therapy is still in its infancy. Multiple factors contribute to limited response, including the heterogeneity of PCa, the cold tumor microenvironment, and a low number of neoantigens. Significant effort is being invested in improving immune-based PCa therapies. This review is a summary of the status of immunotherapy in treating PCa, with a discussion of multiple immune modalities, including vaccines, adoptively transferred T cells, and bispecific T cell engagers, some of which are undergoing clinical trials. In addition, this review also focuses on emerging mechanism-based small-molecule tyrosine kinase inhibitors with immune modulatory properties that, either as single agents or in combination with other immunotherapies, have the potential to improve clinical outcomes.

Metabolic regulation of T cell development

T cell development in the thymus is tightly controlled by complex regulatory mechanisms at multiple checkpoints. Currently, many studies have focused on the transcriptional and posttranslational control of the intrathymic journey of T-cell precursors. However, over the last few years, compelling evidence has highlighted cell metabolism as a critical regulator in this process. Different thymocyte subsets are directed by distinct metabolic pathways and signaling networks to match the specific functional requirements of the stage. Here, we epitomize these metabolic alterations during the development of a T cell and review several recent works that provide insights into equilibrating metabolic quiescence and activation programs. Ultimately, understanding the interplay between cellular metabolism and T cell developmental programs may offer an opportunity to selectively regulate T cell subset functions and to provide potential novel therapeutic approaches to modulate autoimmunity.

Overexpression of RhoH Permits to Bypass the Pre-TCR Checkpoint

RhoH, an atypical small Rho-family GTPase, critically regulates thymocyte differentiation through the coordinated interaction with Lck and Zap70. Therefore, RhoH deficiency causes defective T cell development, leading to a paucity of mature T cells. Since there has been no gain-of-function study on RhoH before, we decided to take a transgenic approach to assess how the overexpression of RhoH affects the development of T cells. Although RhoH transgenic (RhoH^tg) mice expressed three times more RhoH protein than wild-type mice, β-selection, positive, and negative selection in the thymus from RhoH^tg mice were unaltered. However, transgenic introduction of RhoH into Rag2 deficient mice resulted in the generation of CD4⁺CD8⁺ (DP) thymocytes, indicating that overexpression of RhoH could bypass β-selection without TCRβ gene rearrangement. This was confirmed by the in vitro development of DP cells from Rag2^-/-RhoH^tg DN3 cells on TSt-4/Dll-1 stroma in an Lck dependent manner. Collectively, our results indicate that an excess amount of RhoH is able to initiate pre-TCR signaling in the absence of pre-TCR complexes.

Correlation of overall survival with gene expression profiles in a prospective study of resectable esophageal cancer

PURPOSE

Preoperative chemotherapy has demonstrated a survival benefit for patients with potentially resectable esophageal cancer; however, currently it is not possible to predict the benefit of this treatment for an individual patient. This prospective study was designed to correlate gene expression profiles with clinical outcome in this setting.

PATIENTS AND METHODS

Eligible patients were deemed to have resectable disease after staging by computed tomography, endoscopic ultrasound, and laparoscopy as indicated and following discussion at the multidisciplinary team meeting. All patients received neoadjuvant platinum and fluoropyrimidine-based chemotherapy; and clinical data were entered prospectively onto a study-specific database. Total RNA was isolated from pretreatment tumor biopsies obtained at baseline endoscopy and analyzed using a cDNA array consisting of 22,000 cDNA clones.

RESULTS

Of the patients with adequate follow-up accrued between 2002 and 2005, 35 satisfied the quality control measures for the microarray profiling. Median follow-up was 938 days. Supervised hierarchical clustering of normalized data revealed 165 significantly differentially expressed genes based on overall survival (OS; P < .01) with 2 distinct clusters: a poor outcome group: N = 17 (1 year OS 46.2%) and a good outcome group: N = 18 (1 year OS 100%). Genes identified included those previously associated with esophageal cancer and, interestingly, a group of genes encoding proteins involved in the regulation of the TOLL receptor-signaling pathway.

CONCLUSION

This initial study has highlighted groups of tumors with distinct gene expression profiles based on survival and warrants further validation in a larger cohort. This approach may further our understanding of individual tumor biology and thus facilitate the development of tailored treatment.

Anti-Pim-1 mAb inhibits activation and proliferation of T lymphocytes and prolongs mouse skin allograft survival

Pim-1 is an important signaling molecule mediating cell proliferation and survival. Our previous study identified a Pim-1 specific monoclonal antibody, P9, with significant inhibitory effect on cell proliferation. Herein, we report that P9 inhibited the activation and proliferation of PHA-stimulated human PBMC and induced them to undergo apoptosis. In contrast, P9 showed little effect on freshly isolated human blood T lymphocytes which poorly expressed Pim-1. P9 also detected an up-regulation of Pim-1 in mouse lymphocytes after mitogen stimulation, and showed similar selective inhibition on stimulated cells as observed with hPBMC. Furthermore, P9 inhibited the in vitro mixed lymphocyte reaction and P9 treatment significantly prolonged the survival of mouse skin allografts (P<0.001). It is concluded that Pim-1 expression correlates with lymphocyte proliferation and activation. P9 functions as a Pim-1 antagonist and is potential for immunosuppressive therapy.

Myocardial AKT: the omnipresent nexus

One of the greatest examples of integrated signal transduction is revealed by examination of effects mediated by AKT kinase in myocardial biology. Positioned at the intersection of multiple afferent and efferent signals, AKT exemplifies a molecular sensing node that coordinates dynamic responses of the cell in literally every aspect of biological responses. The balanced and nuanced nature of homeostatic signaling is particularly essential within the myocardial context, where regulation of survival, energy production, contractility, and response to pathological stress all flow through the nexus of AKT activation or repression. Equally important, the loss of regulated AKT activity is primarily the cause or consequence of pathological conditions leading to remodeling of the heart and eventual decompensation. This review presents an overview compendium of the complex world of myocardial AKT biology gleaned from more than a decade of research. Summarization of the widespread influence that AKT exerts upon myocardial responses leaves no doubt that the participation of AKT in molecular signaling will need to be reckoned with as a seemingly omnipresent regulator of myocardial molecular biological responses.

For better or for worse: the role of Pim oncogenes in tumorigenesis

Pim oncogenes are overexpressed in a wide range of tumours from a haematological and epithelial origin. Pim genes encode serine/threonine kinases that have been shown to counteract the increased sensitivity to apoptosis induction that is associated with MYC-driven tumorigenesis. Recently, considerable progress has been made in characterizing the pathways of PIM-mediated survival signalling. Given the unique structure of their active site and the minimal phenotype of mice mutant for all Pim family members, these oncogenes might be promising targets for highly specific and selective drugs with favourable toxicity profiles. In this Review, we discuss the physiological functions and oncogenic activities of Pim kinases.

Overexpression of Pim-1 is associated with poor prognosis in patients with esophageal squamous cell carcinoma

BACKGROUND AND OBJECTIVES

It is well known that provirus integration site for Moloney murine leukemia virus 1 (Pim-1) plays an essential role in the occurrence and development of tumors. Here, we investigated expression of Pim-1 in esophageal squamous cell carcinoma (ESCC) and assessed the correlation between Pim-1 level and prognosis of the patients with ESCC.

METHODS

Expression of Pim-1 was investigated by RT-PCR, immunohistochemistry, and in situ hybridization methods. Kaplan-Meier statistics was used to examine the relationship between levels of Pim-1 and prognosis using log-rank test.

RESULTS

The results demonstrated that ESCC tissues appeared strong expression levels of Pim-1 mRNA and protein while the normal esophageal tissues were either negative or showed only weak Pim-1 mRNA and protein levels. In addition, we found that Pim-1 expression was significantly correlated with histology grade, clinical staging, and lymph node metastasis (all P < 0.05), but not related to age and sex (all P > 0.05). Furthermore, the results of survival rates analyzed by Kaplan-Meier curve revealed that patients with high Pim-1 mRNA and protein expressions had a poorer prognosis than those with the low Pim-1 expression (P = 0.010 and 0.001, respectively).

CONCLUSION

These findings demonstrate that Pim-1 may be used as molecular marker for predicting the prognosis of patients with ESCC.

Mitochondrial integrity: preservation through Akt/Pim-1 kinase signaling in the cardiomyocyte

The central role of mitochondria as mediators of cell survival is indisputable and gathering increasing attention as a focal point for interventional strategies to mitigate apoptotic cell death in the wake of cardiomyopathic injury. A legacy of signal transduction studies has proven that mitochondrial integrity can be enhanced by kinases involved in cell survival. Among the many survival signaling cascades under investigation, the wide-ranging impact of Akt upon mitochondrial biology is well known. However, despite years of investigation, emerging research continues to reveal new mechanisms governing the protective effects of Akt signaling in the context of cardiomyocyte mitochondria. This review focuses on two emerging pathways that mediate preservation of mitochondrial function downstream of Akt: hexokinase and Pim-1 kinase.

Unequal Contribution of Akt Isoforms in the Double-Negative to Double-Positive Thymocyte Transition

Pre-TCR signals regulate the transition of the double-negative (DN) 3 thymocytes to the DN4, and subsequently to the double-positive (DP) stage. In this study, we show that pre-TCR signals activate Akt and that pharmacological inhibition of the PI3K/Akt pathway, or combined ablation of Akt1 and Akt2, and to a lesser extent Akt1 and Akt3, interfere with the differentiation of DN3 and the accumulation of DP thymocytes. Combined ablation of Akt1 and Akt2 inhibits the proliferation of DN4 cells, while combined ablation of all Akt isoforms also inhibits the survival of all the DN thymocytes. Finally, the combined ablation of Akt1 and Akt2 inhibits the survival of DP thymocytes. Constitutively active Lck-Akt1 transgenes had the opposite effects. We conclude that, following their activation by pre-TCR signals, Akt1, Akt2, and, to a lesser extent, Akt3 promote the transition of DN thymocytes to the DP stage, in part by enhancing the proliferation and survival of cells undergoing beta-selection. Akt1 and Akt2 also contribute to the differentiation process by promoting the survival of the DP thymocytes.

Pim-1 kinase phosphorylates RUNX family transcription factors and enhances their activity

Background

The pim family genes encode oncogenic serine/threonine kinases which in hematopoietic cells have been implicated in cytokine-dependent signaling as well as in lymphomagenesis, especially in cooperation with other oncogenes such as myc, bcl-2 or Runx family genes. The Runx genes encode α-subunits of heterodimeric transcription factors which regulate cell proliferation and differentiation in various tissues during development and which can become leukemogenic upon aberrant expression.

Results

Here we have identified novel protein-protein interactions between the Pim-1 kinase and the RUNX family transcription factors. Using the yeast two-hybrid system, we were able to show that the C-terminal part of human RUNX3 associates with Pim-1. This result was confirmed in cell culture, where full-length murine Runx1 and Runx3 both coprecipitated and colocalized with Pim-1. Furthermore, catalytically active Pim-1 kinase was able to phosphorylate Runx1 and Runx3 proteins and enhance the transactivation activity of Runx1 in a dose-dependent fashion.

Conclusion

Altogether, our results suggest that mammalian RUNX family transcription factors are novel binding partners and substrates for the Pim-1 kinase, which may be able to regulate their activities during normal hematopoiesis as well as in leukemogenesis.

Overexpression of Pim-1 during progression of prostatic adenocarcinoma

AIMS

Pim-1 is a serine/threonine kinase that has been shown to play an integral role in the development of a number of human cancers, such as haematolymphoid malignancies. Recently, evidence has shown Pim-1 to be important in prostatic carcinogenesis. In order to further our understanding of its role in prostate cancer, we investigated Pim-1 expression in normal, premalignant, and malignant prostate tissue.

METHODS

Using immunohistochemistry, Pim-1 expression was analysed in prostate tissue from 120 radical prostatectomy specimens. In each case, Pim-1 staining was evaluated in benign prostatic epithelium, high grade prostatic intraepithelial neoplasia (PIN), and prostatic adenocarcinoma. The number of positively staining cells was estimated, and the intensity of staining was scored on a scale of 0 to 3+.

RESULTS

Pim-1 immunoreactivity was identified in 120 cases (100%) of adenocarcinoma, 120 cases (100%) of high grade PIN, and 62 cases (52%) of benign glands. The number of cells staining in benign epithelium (mean 34%) was much lower than that in high grade PIN (mean 80%; p<0.0001) or adenocarcinoma (mean, 84%; p<0.0001). There was no significant difference between high grade PIN and adenocarcinoma in the percentage of cells staining positively for Pim-1 (p = 0.34). The staining intensity for Pim-1 was significantly lower in benign prostatic epithelium than in PIN and adenocarcinoma (p<0.001). There was no statistically significant correlation between the level of Pim-1 expression and Gleason score, patient age, tumour stage, lymph node metastasis, perineural invasion, vascular invasion, surgical margin status, extraprostatic extension, or seminal vesicle invasion.

CONCLUSIONS

Pim-1 expression is elevated in PIN and prostatic adenocarcinoma compared with benign prostatic epithelium. This finding suggests that upregulation of Pim-1 may play a role in prostatic neoplasia.

Pim-1 kinase inhibits the activation of reporter gene expression in Elk-1 and c-Fos reporting systems but not the endogenous gene expression: an artifact of the reporter gene assay by transient co-transfection

We have studied the molecular mechanism and signal transduction of pim-1, an oncogene encoding a serine-threonine kinase. This is a true oncogene which prolongs survival and inhibits apoptosis of hematopoietic cells. In order to determine whether the effects of Pim-1 occur by regulation of the mitogen-activated protein kinase pathway, we used a transcriptional reporter assay by transient co-transfection as a screening method. In this study, we found that Pim-1 inhibited the Elk-1 and NFkappaB transcriptional activities induced by activation of the mitogen-activated protein kinase cascade in reporter gene assays. However, Western blots showed that the induction of Elk-1-regulated expression of endogenous c-Fos was not affected by Pim-1. The phosphorylation and activation of neither Erk1/2 nor Elk-1 was influenced by Pim-1. Also, in the gel shift assay, the pattern of endogenous NFkappaB binding to its probe was not changed in any manner by Pim-1. These data indicate that Pim-1 does not regulate the activation of Erk1/2, Elk-1 or NFkappaB. These contrasting results suggest a pitfall of the transient co-transfection reporter assay in analyzing the regulation of transcription factors outside of the chromosome context. It ensures that results from reporter gene expression assay should be verified by study of endogenous gene expression.

Fuel feeds function: energy metabolism and the T-cell response

Ligation of antigen receptors at the surface of lymphocytes initiates a transcriptional and translational response that is required for cellular proliferation and effector function. By contrast, co-stimulatory-molecule ligation contributes to the immune response by allowing the uptake and utilization of extracellular nutrients to provide energy for cellular proliferation and effector functions. Growth factors also potentiate the ability of lymphocytes to metabolically switch between resting and proliferative states. Lymphocytes that do not receive these signals fail to increase their metabolism to meet the higher bioenergetic demands of cell growth and are either deleted or rendered unresponsive to mitogenic signals. In this Review, we describe how T cells actively acquire metabolic substrates from their environment to meet these energy demands and respond appropriately to pathogens.

Prolactin affects both survival and differentiation of T-cell progenitors

We have analysed the in vitro effects of prolactin on thymocyte development concluding that PRL favours the survival and differentiation of T-cell progenitors. Fetal, adult thymocytes and CD45(+) fetal liver lymphoid progenitors express PRL-R. PRL induces survival, proliferation and differentiation of lymphoid progenitors whereas both an anti-PRL antiserum and an anti-PRL-R mAb block T-cell development accumulating CD25(+)DN (CD4(-)CD8(-)) cells. Furthermore, IL2 rescues the blockade of T-cell development in FTOC treated with anti-PRL antiserum but PRL does not recover cultures treated with an anti-IL2R alpha chain mAb, which drastically blocks the T-cell development. These results support IL2/IL2R mediation of PRL effects on developing thymocytes.