CDK Inhibitors and FDA: Approved and Orphan

The protein kinases are a large family of enzymes which catalyze protein phosphorylation at certain amino acids [...].

Starvation mediates pancreatic cancer cell sensitivity to ferroptosis via ERK1/2, JNK and changes in the cell mesenchymal state

Pancreatic cancer is a highly metastatic and therapy‑resistant disease. In the present study, the prospects of a novel approach to kill pancreatic cancer cells were examined: Starvation combined with ferroptosis induction. Established pancreatic cancer cell lines (Miapaca2, Panc‑1, Su.86.86 and T3M4), as well as a unique cell line, Capan‑26, which was originally derived in the authors' laboratory, were used. Cells were deprived from growth factors, amino acids and pseudo‑starved using treatment with mTOR inhibitors; erastin was used to induce ferroptosis. Cell viability and lipid peroxidation measurements using flow cytometry revealed that the starved pancreatic cancer cells reacted differently to ferroptosis induction: The Panc‑1, Su.86.86 and T3M4 cells gained sensitivity, while the Miapaca2 cells acquired resistance. Fluorescence microscopy revealed that ERK1/2 translocated to the nucleus of the starved pancreatic cancer cells. Moreover, ERK1/2 pharmacological inhibition with SCH772984 prevented erastin‑induced ferroptosis in the starved Panc‑1, Su.86.86 and T3M4 cells. Confocal microscopy also indicated JNK activation. However, the inhibition of this kinase revealed its unexpected role in oxidative stress management: Treatment with the JNK inhibitor, SP600125, increased the viability of pseudo‑starved cells following erastin treatment. In addition, the FBS‑starved Miapaca2 and Capan‑26 cells transitioned between epithelial and mesenchymal cell states. The results were further confirmed using wound healing assays, western blot analysis and microscopic analysis of epithelial‑to‑mesenchymal transition (EMT) markers. Mesenchymal properties were associated with a higher sensitivity to erastin, whereas epithelial‑like cells were more resistant. Finally, it was demonstrated that compounds targeting EMT‑related signaling pathways increased cell sensitivity to erastin. On the whole, these results confirm that in starved pancreatic cancer cells, ERK1/2 and JNK signaling, as well as switching between epithelial and mesenchymal states mediates sensitivity to erastin and reveal novel therapeutic prospects of the combination of starvation with ferroptosis induction.

Anti-Cancer Drugs Targeting Protein Kinases Approved by FDA in 2020

Cancers are a large group of diseases that mostly emerge because of the uncontrollable action of many different genes in human cells [...].

Proteomic Analysis of Breast Cancer Resistance to the Anticancer Drug RH1 Reveals the Importance of Cancer Stem Cells

Antitumor drug resistance remains a major challenge in cancer chemotherapy. Here we investigated the mechanism of acquired resistance to a novel anticancer agent RH1 designed to be activated in cancer cells by the NQO1 enzyme. Data show that in some cancer cells RH1 may act in an NQO1-independent way. Differential proteomic analysis of breast cancer cells with acquired resistance to RH1 revealed changes in cell energy, amino acid metabolism and G2/M cell cycle transition regulation. Analysis of phosphoproteomics and protein kinase activity by multiplexed kinase inhibitor beads showed an increase in the activity of protein kinases involved in the cell cycle and stemness regulation and downregulation of proapoptotic kinases such as JNK in RH1-resistant cells. Suppression of JNK leads to the increase of cancer cell resistance to RH1. Moreover, resistant cells have enhanced expression of stem cell factor (SCF) and stem cell markers. Inhibition of SCF receptor c-KIT resulted in the attenuation of cancer stem cell enrichment and decreased amounts of tumor-initiating cells. RH1-resistant cells also acquire resistance to conventional therapeutics while remaining susceptible to c-KIT-targeted therapy. Data show that RH1 can be useful to treat cancers in the NQO1-independent way, and targeting of the cancer stem cells might be an effective approach for combating resistance to RH1 therapy.

Non-Coding RNAs in Glioma

Glioma is the most aggressive brain tumor of the central nervous system. The ability of glioma cells to migrate, rapidly diffuse and invade normal adjacent tissue, their sustained proliferation, and heterogeneity contribute to an overall survival of approximately 15 months for most patients with high grade glioma. Numerous studies indicate that non-coding RNA species have critical functions across biological processes that regulate glioma initiation and progression. Recently, new data emerged, which shows that the cross-regulation between long non-coding RNAs and small non-coding RNAs contribute to phenotypic diversity of glioblastoma subclasses. In this paper, we review data of long non-coding RNA expression, which was evaluated in human glioma tissue samples during a five-year period. Thus, this review summarizes the following: (I) the role of non-coding RNAs in glioblastoma pathogenesis, (II) the potential application of non-coding RNA species in glioma-grading, (III) crosstalk between lncRNAs and miRNAs (IV) future perspectives of non-coding RNAs as biomarkers for glioma.

Proteomic Identification of FLT3 and PCBP3 as Potential Prognostic Biomarkers for Pancreatic Cancer

BACKGROUND/AIM

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest types of cancer, particularly due to its aggressive course and challenging diagnostics in early-stage disease. The aim of this study was to discover new potential prognostic and diagnostic pancreatic cancer biomarkers.

MATERIALS AND METHODS

The proteomes of 37 samples from pancreatic cancer, inflammatory or healthy pancreatic tissue derived through in-depth differential proteomic analysis were compared.

RESULTS

A set of candidate proteins as pancreatic cancer-specific diagnostic or prognostic biomarkers were identified. Survival data of patients after two-year follow-up indicated FLT3 and PCBP3 proteins as potential biomarkers for favourable pancreatic cancer prognosis. The levels of PCBP3 correlated with tumour stage and FLT3 levels, were evaluated as independent prognostic marker.

CONCLUSION

FLT3 and PCBP3 represent potential biomarkers for improved individualized pancreatic cancer prognosis. Moreover, FLT3 may play a role in future treatment selection.

Kinases and Cancer

Protein kinases are a large family of enzymes catalyzing protein phosphorylation. The human genome contains 518 protein kinase genes, 478 of which belong to the classical protein kinase family and 40 are atypical protein kinases [...].

The Potential Role of Akt Phosphorylation in Human Cancers

Akt/protein kinase B (PKB) is a serine/threonine kinase which is implicated in mediating a variety of biological responses including cell growth, proliferation and survival. Akt is activated by phosphorylation on two critical residues, namely threonine 308 (Thr308) and serine 473 (Ser473). Several studies have found Akt2 to be amplified or overexpressed at the mRNA level in various tumor cell lines and in a number of human malignancies such as colon, pancreatic and breast cancers. Nevertheless, activation of Akt isoforms by phosphorylation appears to be more clinically significant than Akt2 amplification or overexpression. Many studies in the past 4–5 years have revealed a prognostic and/or predictive role of Akt phosphorylation in breast, prostate and non-small cell lung cancer. Several publications suggest a role of phosphorylated Akt also in endometrial, pancreatic, gastric, tongue and renal cancer. However, different types of assays were used in these studies. Before assessment of P-Akt can be incorporated into routine clinical practice, all aspects of the assay methodology will have to be standardized.

JNK, p38, ERK, and SGK1 Inhibitors in Cancer

Mitogen-activated protein kinases (MAP kinases) are a family of kinases that regulates a range of biological processes implicated in the response to growth factors like latelet-derived growth factor (PDGF), epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), and stress, such as ultraviolet irradiation, heat shock, and osmotic shock. The MAP kinase family consists of four major subfamilies of related proteins (extracellular regulated kinases 1/2 (ERK1/2), c-Jun N-terminal kinase (JNK), p38, and extracellular regulated kinase 5 (ERK5)) and regulates numerous cellular activities, such as apoptosis, gene expression, mitosis, differentiation, and immune responses. The deregulation of these kinases is shown to be involved in human diseases, such as cancer, immune diseases, inflammation, and neurodegenerative disorders. The awareness of the therapeutic potential of the inhibition of MAP kinases led to a thorough search for small-molecule inhibitors. Here, we discuss some of the most well-known MAP kinase inhibitors and their use in cancer research.

The expression of cancer stem cell markers in human colorectal carcinoma cells in a microenvironment dependent manner

Numerous lines of evidence support the hierarchical model of cancer development and tumor initiation. According to the theory, cancer stem cells play a crucial role in the formation of the tumor and should be targeted for more effective anticancer treatment. However, cancer stem cells quickly loose their characteristics when propagated as 2D cell culture, indicating that the 2D cell culture does not provide the appropriate settings to maintain an in vivo environment. In this study we have investigated the expression of self-renewal, cancer stem cell and epithelial to mesenchymal transition markers after the transfer of human colorectal carcinoma cell DLD1 and HT29 lines from 2D cell cultures to scaffold-attached laminin rich extracellular matrix and scaffold-free multicellular spheroid 3D culture models. Based on the up-regulated expression of multipotency, CSC and EMT markers, our data suggests that human colorectal carcinoma cells grown in 3D exhibit enhanced cancer stem cell characteristics. Therefore, in order to design more efficient targeted therapies, we suggest that 3D cell culture models should be employed in cancer stem cell research.

Metabolomics in pancreatic cancer biomarkers research

Pancreatic cancer is one of the worst prognoses of all malignancies. More than 40,000 deaths a year from this disease are observed in European Union alone. The only possibly curative treatment of pancreatic cancer is surgery, yet only 15-20% of patients have operable disease and even patients, which go through surgery and adjuvant chemotherapy, survival is less than 30%. The sensitive and specific biomarkers which could be used for the advance of early diagnostics are needed and constantly researched. Metabolomics is a technology which analyzes the concentrations of low-molecular-weight metabolites (the metabolome) has lately effectively developed due to the improvements in analytical technology. Metabolome analysis can be a one of the useful approaches for the biomarker discovery and disease diagnosis. Here we discuss recent discoveries in the field of pancreatic cancer metabolomics as well as the most promising biomarkers for diagnostics, prognosis and prediction.

Multi-kinase inhibitors, AURKs and cancer

Inhibitors that impact function of kinases are valuable both for the biological research as well as therapy of kinase-associated diseases, such as different cancers. There are quite a number of inhibitors, which are quite specific for certain kinases and several of them are either already approved for the cancer therapy or are in clinical studies of various phases. However, that does not mean that each single kinase inhibitor is suitable for targeted therapy. Some of them are not effective others might be toxic or fail some other criteria for the use in vivo. On the other hand, even in case of successful therapy, many responders eventually develop resistance to the inhibitors. The limitations of various single kinase inhibitors can be fought using compounds which target multiple kinases. This tactics can increase effectiveness of the inhibitors by the synergistic effect or help to diminish the likelihood of drug resistance. To date, several families of kinases are quite popular targets of the inhibition in cancers, such as tyrosine kinases, cycle-dependent kinases, mitogen-activated protein kinases, phosphoinositide 3-kinases as well as their pathway "players" and aurora kinases. Aurora kinases play an important role in the control of the mitosis and are often altered in diverse human cancers. Here, we will describe the most interesting multi-kinase inhibitors which inhibit aurora kinases among other targets and their use in preclinical and clinical cancer studies.

JNK inhibitors: is there a future?

JNK is a subfamily of MAP kinases that hat regulates a range of biological processes implicated in response to stress, such as cytokines, ultraviolet irradiation, heat shock, and osmotic shock as well as growth factors like PDGF, EGF, FGF, <em>etc</em>. They were originally identified as kinases that bind and phosphorylate JUN on S63 and Se73 within its transcriptional activation domain. The deregulation of these kinases is shown to be involved in human diseases, such as cancer, immune diseases and neurodegenerative disorders. The realization of the therapeutic potential of the inhibition of JNKs led to a thorough search for small-molecule inhibitors first for research purposes, but later also for therapeutic applications. Here, we discuss some of the most well-known JNK inhibitors and their use in basic research or clinical science.

Roscovitine in cancer and other diseases

Roscovitine [CY-202, (R)-Roscovitine, Seliciclib] is a small molecule that inhibits cyclin-dependent kinases (CDKs) through direct competition at the ATP-binding site. It is a broad-range purine inhibitor, which inhibits CDK1, CDK2, CDK5 and CDK7, but is a poor inhibitor for CDK4 and CDK6. Roscovitine is widely used as a biological tool in cell cycle, cancer, apoptosis and neurobiology studies. Moreover, it is currently evaluated as a potential drug to treat cancers, neurodegenerative diseases, inflammation, viral infections, polycystic kidney disease and glomerulonephritis. This review focuses on the use of roscovitine in the disease model as well as clinical model research.

Highlights of the Latest Advances in Research on CDK Inhibitors

Uncontrolled proliferation is the hallmark of cancer and other proliferative disorders and abnormal cell cycle regulation is, therefore, common in these diseases. Cyclin-dependent kinases (CDKs) play a crucial role in the control of the cell cycle and proliferation. These kinases are frequently deregulated in various cancers, viral infections, neurodegenerative diseases, ischemia and some proliferative disorders. This led to a rigorous pursuit for small-molecule CDK inhibitors for therapeutic uses. Early efforts to block CDKs with nonselective CDK inhibitors led to little specificity and efficacy but apparent toxicity, but the recent advance of selective CDK inhibitors allowed the first successful efforts to target these kinases for the therapies of several diseases. Major ongoing efforts are to develop CDK inhibitors as monotherapies and rational combinations with chemotherapy and other targeted drugs.

Increased Level of Phosphorylated ShcA Measured by Chemiluminescence-Linked Immunoassay Is a Predictor of Good Prognosis in Primary Breast Cancer Expressing Low Levels of Estrogen Receptor

The SH2 domain-containing adaptor protein ShcA is a proto-oncogene involved in growth factor receptor signaling. The role of phosphorylated ShcA is to link receptor tyrosine kinases with the SH2-containing adaptor protein Grb2, thus facilitating signal transduction from receptor tyrosine kinases to Ras, leading to MAPK activation. The present study was designed to investigate the prognostic significance of phosphorylated ShcA in primary breast cancer and its association in the interactions between the ER and ErbB2 pathways. Using a two-site chemiluminescence-linked immunosorbent assay, we detected the quantitative expression levels of total tyrosine- and threonine-phosphorylated ShcA in cytosol fractions obtained from fresh frozen tissue samples of 153 selected primary breast cancer patients. ShcA phosphorylation was not associated with nodal status, estrogen receptor (ER) status or grading. High levels of both tyrosine (pYShcA) and serine (pSShcA) phosphorylated ShcA correlated with good prognosis (p < 0.01), with respect to both disease-free (DFS) and overall survival (OS). In addition, pShcA levels were found to correlate with threonine-phosphorylated ErbB2 and inversely with phosphorylated Akt (pAkt), as well as ErbB2 and ER expression levels. Our findings demonstrate that ShcA activation in primary breast cancer patients correlates with low levels of ER, and is associated with good prognosis.

Protein chip based miniaturized assay for the simultaneous quantitative monitoring of cancer biomarkers in tissue extracts

A multiplexed fluorescence immunoassay using a novel planar waveguide technology-based microarray system, ZeptoMARK (Zeptosens), was developed to detect simultaneously urokinase-type plasminogen activator (uPA), plasminogen activator inhibitor-1 (PAI-1), and vascular endothelial growth factor (VEGF) in extracts of breast cancer tissues. The three analytes assay was cross-validated with single-analyte ELISA/chemiluminescence immunosorbent assay tests, revealing good correlations and enhanced assay sensitivities (LODs) of 1 pg/mL for uPA, 33 pg/mL for PAI-1, and 1 pg/mL for VEGF. Values were well within the 80-120% limits for assay recovery and within the +/-20% limits for assay precision. The uPA, PAI-1, and VEGF results obtained from 50 breast cancer cytosols using the protein array system demonstrated that the microarray-based multiplexed assay is a sensitive and robust tool to be used for the simultaneous quantification of cancer markers in small breast cancer tissue samples (core biopsies). The miniaturized, multiplexed assay format has a potential to be used for the quantitative analysis of a larger set of validated markers with significance in disease management.

Phosphorylation of tyrosine 1248-ERBB2 measured by chemiluminescence-linked immunoassay is an independent predictor of poor prognosis in primary breast cancer patients

ERBB2 (HER2/Neu) gene amplification and overexpression is associated with increased risk of metastases and shorter survival in breast cancer. Tyrosine 1248 is a major phosphorylation site of ERBB2 and reflects the activation status of the receptor. The aim of this study was to investigate the relationships between quantitative levels of pY1248-ERBB2 (p-ERBB2) and the expression of epidermal growth factor receptor (EGFR)-family members, and whether p-ERBB2 could provide additional prognostic value compared with established prognostic markers. For this purpose we developed a highly sensitive chemiluminescence-linked immunoassay (CLISA) and detected p-ERBB2 levels in 70 primary breast cancer biopsies. Phosphorylated ERBB2 correlated with EGFR and ERBB2, and inversely with oestrogen receptor (ER), progesterone receptor (PgR) and ERBB4 expression levels. Additionally, p-ERBB2 was associated with poor clinical outcome in univariate and multivariate Cox regression analysis. Further studies are needed to evaluate the predictive value of p-ERBB2.

Increased level of phosphorylated akt measured by chemiluminescence-linked immunosorbent assay is a predictor of poor prognosis in primary breast cancer overexpressing ErbB-2

Introduction

Akt1, Akt2 and Akt3 kinases are downstream components of phosphoinositol 3-kinase derived signals from receptor tyrosine kinases, which influence cell growth, proliferation and survival. Akt2 overexpression and amplification have been described in breast, ovarian and pancreatic cancers. The present study was designed to investigate the prognostic significance of activated Akt in primary breast cancer and its association with other tumour biomarkers.

Methods

Using a two-site chemiluminescence-linked immunosorbent assay, we measured the quantitative expression levels of total phosphorylated (P-S473) Akt (Akt1/Akt2/Akt3) on cytosol fractions obtained from fresh frozen tissue samples of 156 primary breast cancer patients.

Results

Akt phosphorylation was not associated with nodal status or ErbB-2 protein expression levels. High levels of phosphorylated Akt correlated (P < 0.01) with poor prognosis, and the significance of this correlation increased (P < 0.001) in the subset of patients with ErbB-2 overexpressing tumours. In addition, phosphorylated Akt was found to be associated with mRNA expression levels of several proliferation markers (e.g. thymidylate synthase), measured using quantitative real-time RT-PCR.

Conclusion

Our findings demonstrate that, in breast cancer patients, Akt activation is associated with tumour proliferation and poor prognosis, particularly in the subset of patients with ErbB2-overexpressing tumours.