Tissue microarray cytometry reveals positive impact of homeodomain interacting protein kinase 2 in colon cancer survival irrespective of p53 function

HIPK2 in Colon Cancer: A Potential Biomarker for Tumor Progression and Response to Therapies

Colon cancer, one of the most common and fatal cancers worldwide, is characterized by stepwise accumulation of specific genetic alterations in tumor suppressor genes or oncogenes, leading to tumor growth and metastasis. HIPK2 (homeodomain-interacting protein kinase 2) is a serine/threonine protein kinase and a "bona fide" oncosuppressor protein. Its activation inhibits tumor growth mainly by promoting apoptosis, while its inactivation increases tumorigenicity and resistance to therapies of many different cancer types, including colon cancer. HIPK2 interacts with many molecular pathways by means of its kinase activity or transcriptional co-repressor function modulating cell growth and apoptosis, invasion, angiogenesis, inflammation and hypoxia. HIPK2 has been shown to participate in several molecular pathways involved in colon cancer including p53, Wnt/β-catenin and the newly identified nuclear factor erythroid 2 (NF-E2) p45-related factor 2 (NRF2). HIPK2 also plays a role in tumor-host interaction in the tumor microenvironment (TME) by inducing angiogenesis and cancer-associated fibroblast (CAF) differentiation. The aim of this review is to assess the role of HIPK2 in colon cancer and the underlying molecular pathways for a better understanding of its involvement in colon cancer carcinogenesis and response to therapies, which will likely pave the way for novel colon cancer therapies.

miR-4653-3p overexpression is associated with a poor prognosis of pancreatic ductal adenocarcinoma via HIPK2 downregulation

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignant tumor. Several upregulated and downregulated microRNAs (miRNAs) are associated with invasiveness, tumorigenesis, and prognosis of PDAC. Herein, using in situ hybridization, we evaluated miR-4653-3p expression and pancreatic intraepithelial neoplasia (PanIN) and the association between miR-4653-3p expression and clinicopathological factors in PDAC patients. The miR-4653-3p target was also identified. Ninety PDAC cases, including 30 each with normal pancreatic ducts, low-grade PanINs, and high-grade PanINs, were evaluated. miR-4653-3p expression increased in the order-normal pancreatic duct, low-grade PanIN, high-grade PanIN, and PDAC-with no expression detected in normal pancreatic duct. High expression significantly correlated with advanced pathological T stage, lymph node metastasis, advanced Union for International Cancer Control stage, perineural invasion, venous involvement, and shorter overall and disease-specific survival. Homeodomain Interacting Protein Kinase 2 (HIPK2) was identified as a miR-4653-3p target based on mRNA microarray analysis and database screening. In MIA PaCa-2 cells, miR-4653-3p significantly downregulated HIPK2 expression. HIPK2 expression, unlike that of miR-4653-3p, decreased in the order-normal pancreatic duct, low-grade PanIN, high-grade PanIN, and PDAC. Low HIPK2 expression was associated with shorter overall and disease-specific survival in PDAC patients. Thus, miR-4653-3p associates with tumorigenesis and worse prognosis, partly by reducing HIPK2 expression.

Highly selective inhibitors of protein kinases CLK and HIPK with the furo[3,2-b]pyridine core

The furo [3,2-b]pyridine motif represents a relatively underexplored central pharmacophore in the area of kinase inhibitors. Herein, we report flexible synthesis of 3,5-disubstituted furo [3,2-b]pyridines that relies on chemoselective couplings of newly prepared 5-chloro-3-iodofuro [3,2-b]pyridine. This methodology allowed efficient second-generation synthesis of the state-of-the-art chemical biology probe for CLK1/2/4 MU1210, and identification of the highly selective inhibitors of HIPKs MU135 and MU1787 which are presented and characterized in this study, including the X-ray crystal structure of MU135 in HIPK2. chemical biology probe.

HIPK2 Overexpression and Its Prognostic Role in Human Papillomavirus-Positive Tonsillar Squamous Cell Carcinoma

Tonsillar squamous cell carcinomas (TSCCs) are the most common human papillomavirus- (HPV-) associated oropharyngeal cancers with poor prognosis. Homeodomain-interacting protein kinase 2 (HIPK2) is a central regulator of p53, which participates in apoptosis during the DNA damage response. HIPK2 is involved in HPV-associated uterine cervical and cutaneous carcinogenesis through its binding of HPV E6, thereby preventing apoptosis and contributing to tumor progression. However, its clinical and prognostic significance in TSCC remains unclear. HIPK2 mRNA levels were analyzed in 20 normal tonsils and 20 TSCC specimens using real-time reverse transcription polymerase chain reaction. Immunohistochemistry of HIPK2 was performed in 79 resected specimens. HIPK2 was expressed in 57% of the TSCCs, and HIPK2 protein expression and HIPK2 mRNA levels were higher in TSCCs than in normal tonsils. HIPK2 overexpression was associated with poorly differentiated carcinoma and low alcohol consumption and was an independent prognostic factor for overall survival and disease-free survival (DFS) in TSCC and a negative independent prognostic factor for DFS in patients receiving postoperative radiotherapy. HIPK2 overexpression had a significant association with poorer DFS in HPV-positive TSCCs, but not in HPV-negative tumors. HIPK2 overexpression may be a potential prognostic marker for predicting prognoses and a high risk of recurrence, particularly in patients with HPV-positive TSCC.

Homeodomain-Interacting Protein Kinases: Diverse and Complex Roles in Development and Disease

The Homeodomain-interacting protein kinase (Hipk) family of proteins plays diverse, and at times conflicting, biological roles in normal development and disease. In this review we will highlight developmental and cellular roles for Hipk proteins, with an emphasis on the pleiotropic and essential physiological roles revealed through genetic studies. We discuss the myriad ways of regulating Hipk protein function, and how these may contribute to the diverse cellular roles. Furthermore we will describe the context-specific activities of Hipk family members in diseases such as cancer and fibrosis, including seemingly contradictory tumor-suppressive and oncogenic activities. Given the diverse signaling pathways regulated by Hipk proteins, it is likely that Hipks act to fine-tune signaling and may mediate cross talk in certain contexts. Such regulation is emerging as vital for development and in disease.

Greatwall promotes cell transformation by hyperactivating AKT in human malignancies

The PP2A phosphatase is often inactivated in cancer and is considered as a tumour suppressor. A new pathway controlling PP2A activity in mitosis has been recently described. This pathway includes the Greatwall (GWL) kinase and its substrates endosulfines. At mitotic entry, GWL is activated and phosphorylates endosulfines that then bind and inhibit PP2A. We analysed whether GWL overexpression could participate in cancer development. We show that GWL overexpression promotes cell transformation and increases invasive capacities of cells through hyperphosphorylation of the oncogenic kinase AKT. Interestingly, AKT hyperphosphorylation induced by GWL is independent of endosulfines. Rather, GWL induces GSK3 kinase dephosphorylation in its inhibitory sites and subsequent SCF-dependent degradation of the PHLPP phosphatase responsible for AKT dephosphorylation. In line with its oncogenic activity, we find that GWL is often overexpressed in human colorectal tumoral tissues. Thus, GWL is a human oncoprotein that promotes the hyperactivation of AKT via the degradation of its phosphatase, PHLPP, in human malignancies.

HIPK2 expression in progression of cutaneous epithelial neoplasm

BACKGROUND

Homeodomain-interacting protein kinase 2 (HIPK2) is responsible for a DNA damage response, centrally regulating p53. The aberrant HIPK2 expression is known to be involved in carcinogenesis in several malignancies. However, the correlation of HIPK2 expression along with progression of cutaneous epithelial neoplasm has not been investigated.

METHODS

Using immunohistochemistry and real-time reverse transcription-polymerase chain reaction, we examined the correlation between HIPK2 and HIPK2-related protein expressions and the progression of some cutaneous epithelial neoplasms (i.e., actinic keratosis, Bowen's disease, keratoacanthoma, squamous cell carcinoma, and basal cell carcinoma).

RESULTS

HIPK2 expression was distinct between preinvasive and invasive lesions: the expression decreased in keratoacanthoma (none of eight) and squamous cell carcinoma (five of 35) compared to actinic keratosis (12 of 19) and Bowen's disease (10 of 23) (P < 0.001). HIPK2 expression was also negatively correlated with aggressiveness of basal cell carcinoma; high-risk subtypes showed lower HIPK2 expression than did low-risk subtypes (P < 0.001). HIPK2 mRNA expression of each tumor group was significantly higher than that of normal skin. HIPK2 mRNA expression of each tumor group was not correlated with the relevant HIPK2 protein expression, which was consistent with previous studies.

CONCLUSIONS

HIPK2 expression tends to be decreased along tumor progression and may be involved with the invasive potential, suggesting a possible tumor suppressor role for HIPK2.

The MAP3K ZAK, a novel modulator of ERK-dependent migration, is upregulated in colorectal cancer

Often described as a mediator of cell cycle arrest or as a pro-apoptotic factor in stressful conditions, the MAP3K ZAK (Sterile alpha motif and leucine zipper-containing kinase) has also been proven to positively regulate epidermal growth factor receptor (EGFR) and WNT signaling pathways, cancer cell proliferation and cellular neoplastic transformation. Here, we show that both isoforms of ZAK, ZAK-α and ZAK-β are key factors in cancer cell migration. While ZAK depletion reduced cell motility of HeLa and HCT116 cells, its overexpression triggered the activation of all three mitogen-activated protein kinases (MAPKs), extracellular signal-regulated kinase (ERK), c-JUN N-terminal kinase (JNK) and p38, as well as an increase in cell motion. On the contrary, the kinase-dead mutants, ZAK-α K45M and ZAK-β K45M, were not able to provoke such events, and instead exerted a dominant-negative effect on MAPK activation and cell migration. Pharmacological inhibition of ZAK by nilotinib, preventing ZAK-autophosphorylation and thereby auto-activation, led to the same results. Activated by epidermal growth factor (EGF), we further showed that ZAK constitutes an essential element of the EGF/ERK-dependent cell migration pathway. Using public transcriptomic databases and tissue microarrays, we finally established that, as strong factors of the EGFR signaling pathway, ZAK-α and/or ZAK-β transcripts and protein(s) are frequently upregulated in colorectal adenoma and carcinoma patients. Notably, gene set enrichment analysis disclosed a significant correlation between ZAK+ colorectal premalignant lesions and gene sets belonging to the MAPK/ERK and motility-related signaling pathways of the reactome database, strongly suggesting that ZAK induces such pro-tumoral reaction cascades in human cancers.

Molecular markers in colorectal cancer: clinical relevance in stage II colon cancer

SUMMARY Colorectal cancer is the second most common cause of cancer death in developed countries. Adjuvant chemotherapy is standard for stage III colorectal cancer but its use in stage II is controversial. Several clinicopathological factors have been described to define a high-risk group among stage II colon cancers, which can aid the selection of patients who may benefit from chemotherapy. Local tumor invasion (T4), high histological grade, obstruction and perforation at diagnosis, and number of lymph nodes removed are the most widely accepted factors. Several molecular factors have been also investigated as prognostic candidate biomarkers. DNA ploidy, KRAS and TP53 mutations, thymidylate synthase, dihydropyrimidine dehydrogenase, thymidine phosphorylase, loss of heterozygosity on chromosome 18q and microsatellite instability have been widely investigated. The aim of this review is to analyze the current evidence and clinical applications of the classical molecular biomarkers as well as new ones such as BRAF, circulating tumor cells, genome expression signatures and DNA methylation.

HIPK1 drives p53 activation to limit colorectal cancer cell growth

HIPK1 (homeodomain interacting protein kinase 1) is a serine/threonine kinase that belongs to the CMGC superfamily. Emerging data point to the role of HIPK1 in cancer, but it is still not clear whether it acts as a tumor suppressor or promoter. Here we identified HIPK1 as a kinase that is significantly overexpressed in colorectal cancer (CRC) and whose expression is stage-dependent. Being abundantly expressed at the onset of the disease, the HIPK1 level gradually decreased as tumor stage progressed. To further uncover how this factor regulates tumorigenesis and establish whether it constitutes an early factor necessary for neoplastic transformation or for cellular defense, we studied the effect of its overexpression in vitro by investigating various cancer-related signaling cascades. We found that HIPK1 mostly regulates the p53 signaling pathway both in HCT116 and HeLa cells. By phosphorylating p53 on its serine-15, HIPK1 favored its transactivation potential, which led to a rise in p21 protein level and a decline in cell proliferation. Assuming that HIPK1 could impede CRC growth by turning on the p53/p21 pathway, we then checked p21 mRNA levels in patients. Interestingly, p21 transcripts were only increased in a subset of patients expressing high levels of HIPK1. Unlike the rest of the cohort, the majority of these patients hosted a native p53 protein, meaning that such a pro-survival pathway (HIPK1+ > p53 > p21) is active in patients, and that HIPK1 acts rather as a tumor suppressor.

Posttranslational modifications regulate HIPK2, a driver of proliferative diseases

The serine/threonine kinase homeodomain-interacting protein kinase (HIPK2) is a tumor suppressor and functions as an evolutionary conserved regulator of signaling and gene expression. This kinase regulates a surprisingly vast array of biological processes that range from the DNA damage response and apoptosis to hypoxia signaling and cell proliferation. Recent studies show the tight control of HIPK2 by hierarchically occurring posttranslational modifications such as phosphorylation, small ubiquitin-like modifier modification, acetylation, and ubiquitination. The physiological function of HIPK2 as a regulator of cell proliferation and survival has a downside: proliferative diseases. Dysregulation of HIPK2 can result in increased proliferation of cell populations as it occurs in cancer or fibrosis. We discuss various models that could explain how inappropriate expression, modification, or localization of HIPK2 can be a driver for these proliferative diseases.

Zinc supplementation augments in vivo antitumor effect of chemotherapy by restoring p53 function

Activated p53 is necessary for tumor suppression. Homeodomain-interacting protein kinase-2 (HIPK2) is a positive regulator of functional p53. HIPK2 modulates wild-type p53 activity toward proapoptotic transcription and tumor suppression by the phosphorylation of serine 46. Knock-down of HIPK2 interferes with tumor suppression and sensitivity to chemotherapy. Combined administration of adriamycin and zinc restores activity of misfolded p53 and enables the induction of its proapoptotic and tumor suppressor functions in vitro and in vivo. We therefore looked for a cancer model where HIPK2 expression is low. MMTV-neu transgenic mice overexpressing HER2/neu, develop mammary tumors at puberty with a long latency, showing very low expression of HIPK2. Here we show that whereas these tumors are resistant to adriamycin treatment, a combination of adriamycin and zinc suppresses tumor growth in vivo in these mice, an effect evidenced by the histological features of the mammary tumors. The combined treatment of adriamycin and zinc also restores wild-type p53 conformation and induces proapoptotic transcription activity. These findings may open up new possibilities for the treatment of human cancers via the combination of zinc with chemotherapeutic agents, for a selected group of patients expressing low levels of HIPK2, with an intact p53. In addition, HIPK2 may serve as a new biomarker for tumor aggressiveness.