Potent pro-apoptotic combination therapy is highly effective in a broad range of cancers

Primary or acquired therapy resistance is a major obstacle to the effective treatment of cancer. Resistance to apoptosis has long been thought to contribute to therapy resistance. We show here that recombinant TRAIL and CDK9 inhibition cooperate in killing cells derived from a broad range of cancers, importantly without inducing detectable adverse events. Remarkably, the combination of TRAIL with CDK9 inhibition was also highly effective on cancers resistant to both, standard-of-care chemotherapy and various targeted therapeutic approaches. Dynamic BH3 profiling revealed that, mechanistically, combining TRAIL with CDK9 inhibition induced a drastic increase in the mitochondrial priming of cancer cells. Intriguingly, this increase occurred irrespective of whether the cancer cells were sensitive or resistant to chemo- or targeted therapy. We conclude that this pro-apoptotic combination therapy has the potential to serve as a highly effective new treatment option for a variety of different cancers. Notably, this includes cancers that are resistant to currently available treatment modalities.

The Novel, Orally Bioavailable CDK9 Inhibitor Atuveciclib Sensitises Pancreatic Cancer Cells to TRAIL-induced Cell Death

BACKGROUND/AIM

This study was designed to analyse the effects of the novel, orally bioavailable CDK9-inhibitor Atuveciclib (BAY 1143572) in combination with tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) on pancreatic ductal adenocarcinoma (PDAC) cancer cells.

MATERIALS AND METHODS

To assess the effect of combinatorial use of atuveciclib and TRAIL on pancreatic cancer cells, we used an MTT assay, colony formation assay, flow cytometry, and western blot analysis.

RESULTS

Atuveciclib combined with TRAIL significantly reduced the viability of pancreatic cancer cells and their colony formation potential by inducing apoptosis and cell-cycle arrest. Atuveciclib sensitised PDAC cells to TRAIL-induced cell death through the concomitant suppression of cFlip and Mcl-1. A gemcitabine-resistant PDAC cell-line and patient-derived xenograft (PDX) cell lines were also suppressed by this combinatorial approach.

CONCLUSION

This study provides the basis for further preclinical and clinical evaluation of combined treatment with atuveciclib and TRAIL.

Friend or Foe: S100 Proteins in Cancer

S100 proteins are widely expressed small molecular EF-hand calcium-binding proteins of vertebrates, which are involved in numerous cellular processes, such as Ca²⁺ homeostasis, proliferation, apoptosis, differentiation, and inflammation. Although the complex network of S100 signalling is by far not fully deciphered, several S100 family members could be linked to a variety of diseases, such as inflammatory disorders, neurological diseases, and also cancer. The research of the past decades revealed that S100 proteins play a crucial role in the development and progression of many cancer types, such as breast cancer, lung cancer, and melanoma. Hence, S100 family members have also been shown to be promising diagnostic markers and possible novel targets for therapy. However, the current knowledge of S100 proteins is limited and more attention to this unique group of proteins is needed. Therefore, this review article summarises S100 proteins and their relation in different cancer types, while also providing an overview of novel therapeutic strategies for targeting S100 proteins for cancer treatment.

TRAILblazing Strategies for Cancer Treatment

In the late 1990s, tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), a member of the TNF-family, started receiving much attention for its potential in cancer therapy, due to its capacity to induce apoptosis selectively in tumour cells in vivo. TRAIL binds to its membrane-bound death receptors TRAIL-R1 (DR4) and TRAIL-R2 (DR5) inducing the formation of a death-inducing signalling complex (DISC) thereby activating the apoptotic cascade. The ability of TRAIL to also induce apoptosis independently of p53 makes TRAIL a promising anticancer agent, especially in p53-mutated tumour entities. Thus, several so-called TRAIL receptor agonists (TRAs) were developed. Unfortunately, clinical testing of these TRAs did not reveal any significant anticancer activity, presumably due to inherent or acquired TRAIL resistance of most primary tumour cells. Since the potential power of TRAIL-based therapies still lies in TRAIL's explicit cancer cell-selectivity, a desirable approach going forward for TRAIL-based cancer therapy is the identification of substances that sensitise tumour cells for TRAIL-induced apoptosis while sparing normal cells. Numerous of such TRAIL-sensitising strategies have been identified within the last decades. However, many of these approaches have not been verified in animal models, and therefore potential toxicity of these approaches has not been taken into consideration. Here, we critically summarise and discuss the status quo of TRAIL signalling in cancer cells and strategies to force tumour cells into undergoing apoptosis triggered by TRAIL as a cancer therapeutic approach. Moreover, we provide an overview and outlook on innovative and promising future TRAIL-based therapeutic strategies.

The Emerging Role of Cyclin-Dependent Kinases (CDKs) in Pancreatic Ductal Adenocarcinoma

The family of cyclin-dependent kinases (CDKs) has critical functions in cell cycle regulation and controlling of transcriptional elongation. Moreover, dysregulated CDKs have been linked to cancer initiation and progression. Pharmacological CDK inhibition has recently emerged as a novel and promising approach in cancer therapy. This idea is of particular interest to combat pancreatic ductal adenocarcinoma (PDAC), a cancer entity with a dismal prognosis which is owed mainly to PDAC's resistance to conventional therapies. Here, we review the current knowledge of CDK biology, its role in cancer and the therapeutic potential to target CDKs as a novel treatment strategy for PDAC.

CK1α overexpression correlates with poor survival in colorectal cancer

Background

Colorectal cancer (CRC) is the fourth leading cause of cancer related deaths worldwide and prognosis in advanced tumor stage still remains poor. Since CK1 isoforms have been reported to be deregulated in several tumor entities CK1 has emerged as a novel drug target in cancer therapy. In this study we set out to investigate whether CK1α might have the potential to serve as prognostic marker.

Methods

CK1α RNA and protein expression levels in healthy and tumor tissue of CRC patients were analyzed using quantitative real-time PCR and Western Blot analysis, respectively. Prognostic relevance was investigated by correlating obtained CK1α expression levels with patients’ survival rate generating Kaplan-Meier survival plots.

Results

It could be shown that CK1α is overexpressed in colorectal tumor tissue compared to normal tissue and CK1α overexpression in tumor tissue correlates with poor survival in CRC patients. Results become more significant when only considering patients with high-grade tumors, as well as patients assigned to UICC II and UICC III stage. Furthermore, Cox regression analysis revealed that CK1α is an independent prognostic factor. In addition, tumors expressing decreased levels of the kinase reveal positive effects on overall survival when localized in the right colon compared to those in the left side.

Conclusion

In summary, this study provides evidence for the first time that CK1α RNA levels might serve as prognostic marker for CRC.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4019-0) contains supplementary material, which is available to authorized users.

CDK9 is a prognostic marker and therapeutic target in pancreatic cancer

Despite recent advances in diagnosis and therapy, prognosis of pancreatic cancer still remains very poor. Besides valid prognostic markers, novel therapeutic approaches are urgently needed. The family of cyclin-dependent kinases comprises 20 kinases which contribute to malignancy by promoting proliferation, migration, invasion, and apoptotic resistance of cancer cells. In this work, we investigated the role of CDK9 in pancreatic cancer. Immunohistochemical analysis of CDK9 expression in tumor and normal tissue of pancreatic cancer patients revealed an overexpression of CDK9 in pancreatic cancer tissue. In addition, high CDK9 expression in tumor tissue is associated with significantly shortened survival, especially in well-differentiated tumors. Moreover, the therapeutic potential of selective CDK9 inhibition on pancreatic cancer cells was evaluated by analysis of cell viability, long-term survival, and induction of apoptosis and characterized by western blotting and flow cytometry. Pharmacological CDK9 inhibition by SNS-032 drastically reduced cell viability in pancreatic cancer cells and potently suppressed long-term survival. Analyzing the mechanism of action revealed that CDK9 inhibition induced apoptosis and cell cycle arrest in a time-dependent manner by suppression of anti-apoptotic proteins. Furthermore, CDK9 inhibition potently enhances the therapeutic effect of chemotherapeutics in pancreatic cancer cells. In conclusion, we identified CDK9 as a negative prognostic marker in pancreatic cancer. Furthermore, pharmacological CDK9 inhibition is a novel and promising therapeutic approach for pancreatic cancer.

Decreased CK1δ expression predicts prolonged survival in colorectal cancer patients

Cancers arising from the large intestine or rectum are called colorectal cancer (CRC) and represent the fourth leading cause of cancer-related death worldwide. Since casein kinase 1 (CK1) isoforms are involved in many cellular processes and have been reported to be deregulated in various tumor entities, CK1 has become an interesting drug target. In this study, we examined the potential of CK1δ expression levels in tumor tissue of CRC patients as a prognostic biomarker. We show by quantitative RNA expression analyses that decreased CK1δ expression levels in tumor tissue predict prolonged survival rates. Random sampling of CK1δ stained tumor tissue indicates that CK1δ gene expression corresponds with CK1δ protein expression. Especially in low grade (grade 1, grade 2) and in UICC II/III classified tumors decreased CK1δ RNA levels correlate with significantly improved survival rates when the tumor was located in the right colon. We furthermore found gender-specific differences within these subgroups, revealing most significant increase in overall survival rates in male patients with tumors in right colon expressing low levels of CK1δ RNA. Results become even clearer, when only male patients over 50 years were considered. Together, these findings support the assumption that CK1δ might be a prognostic biomarker for CRC thereby providing an interesting drug target for the development of new therapy concepts.