My journey from tyrosine phosphorylation inhibitors to targeted immune therapy as strategies to combat cancer.

Since the 1980s there has been a drive toward personalized targeted therapy for cancer. "Targeted cancer therapy" originally focused on inhibiting essential tumor survival factors, primarily protein tyrosine kinases. The complexity and rapid mutability of tumors, however, enable them to develop resistance to tyrosine kinase inhibitors (TKIs), even when these are multitargeted or applied in combination.

Impact of the Anticancer Drug NT157 on Tyrosine Kinase Signaling Networks.

The small-molecule drug NT157 has demonstrated promising efficacy in preclinical models of a number of different cancer types, reflecting activity against both cancer cells and the tumor microenvironment. Two known mechanisms of action are degradation of insulin receptor substrates (IRS)-1/2 and reduced Stat3 activation, although it is possible that others exist. To interrogate the effects of this drug on cell signaling pathways in an unbiased manner, we have undertaken mass spectrometry-based global tyrosine phosphorylation profiling of NT157-treated A375 melanoma cells.

PSMA-targeted polyinosine/polycytosine vector induces prostate tumor regression and invokes an antitumor immune response in mice.

There is an urgent need for an effective treatment for metastatic prostate cancer (PC). Prostate tumors invariably overexpress prostate surface membrane antigen (PSMA). We designed a nonviral vector, PEI-PEG-DUPA (PPD), comprising polyethylenimine-polyethyleneglycol (PEI-PEG) tethered to the PSMA ligand, 2-[3-(1, 3-dicarboxy propyl)ureido] pentanedioic acid (DUPA), to treat PC.

S101, an Inhibitor of Proliferating T Cells, Rescues Mice From Superantigen-Induced Shock.

Superantigens (SAgs) are extremely potent bacterial toxins, which evoke a virulent immune response, inducing nonspecific T-cell proliferation, rapid cytokine release, and lethal toxic shock, for which there is no effective treatment. We previously developed a small molecule, S101, which potently inhibits proliferating T cells. In a severe mouse model of toxic shock, a single injection of S101 given together with superantigen challenge rescued 100% of the mice.

PSMA-homing dsRNA chimeric protein vector kills prostate cancer cells and activates anti-tumor bystander responses.

The treatment of metastatic androgen-resistant prostate cancer remains a challenge. We describe a protein vector that selectively delivers synthetic dsRNA, polyinosinic/polycytidylic acid (polyIC), to prostate tumors by targeting prostate specific membrane antigen (PSMA), which is overexpressed on the surface of prostate cancer cells.The chimeric protein is built from the double stranded RNA (dsRNA) binding domain of PKR tethered to a single chain anti-PSMA antibody.

Targeting polyIC to EGFR over-expressing cells using a dsRNA binding protein domain tethered to EGF.

Selective delivery of drugs to tumor cells can increase potency and reduce toxicity. In this study, we describe a novel recombinant chimeric protein, dsRBEC, which can bind polyIC and deliver it selectively into EGFR over-expressing tumor cells. dsRBEC, comprises the dsRNA binding domain (dsRBD) of human PKR (hPKR), which serves as the polyIC binding moiety, fused to human EGF (hEGF), the targeting moiety.

HER2-Targeted Polyinosine/Polycytosine Therapy Inhibits Tumor Growth and Modulates the Tumor Immune Microenvironment.

The development of targeted therapies that affect multiple signaling pathways and stimulate antitumor immunity is greatly needed. About 20% of patients with breast cancer overexpress HER2. Small molecules and antibodies targeting HER2 convey some survival benefits; however, patients with advanced disease succumb to the disease under these treatment regimens, possibly because HER2 is not completely necessary for the survival of the targeted cancer cells.

Optimization of liganded polyethylenimine polyethylene glycol vector for nucleic acid delivery.

The delivery of nucleic acids into cells is an attractive approach for cancer therapy. Polyethylenimine (PEI) is among the most efficient nonviral carriers. Recent studies have demonstrated that PEI can be conjugated to targeting ligands, such as epidermal growth factor (EGF) and transferrin (Schaffert et al.

Heterogeneity of gene expression in murine squamous cell carcinoma development-the same tumor by different means.

Transformation is a complex process, involving many changes in the cell. In this work, we investigated the transcriptional changes that arose during the development of squamous cell carcinoma (SCC) in mice. Using microarray analysis, we looked at gene expression during different stages in cancer progression in 31 mice.

Studying protein-peptide interactions using benzophenone units: a case study of protein kinase B/Akt and its inhibitor PTR6154.

Protein-protein interactions (PPIs) govern nearly all processes in living cells. Peptides play an important role in studying PPIs. Peptides carrying photoaffinity labels that covalently bind the interacting protein can be used to obtain more accurate information regarding PPIs.

Metabolic stability of peptidomimetics: N-methyl and aza heptapeptide analogs of a PKB/Akt inhibitor.

Linear peptides suffer from poor pharmacokinetic and pharmacodynamic properties. Peptidomimetics are designed to overcome these pharmacological drawbacks while maintaining the biological effects of the parent peptides. Aza-peptides, in which an alpha carbon is replaced with nitrogen, are promising peptidomimetic analogs; however, little is known about the stability of these analogs toward enzymatic degradation.

Nucleic acid-based therapeutics for glioblastoma.

Nucleic acid based therapeutics offer the possibility of tailor-made treatment of malignant diseases. For recurrent glioblastoma multiforme (GBM), the most aggressive type of brain tumor, no accepted treatment exists, making therapeutically active nucleic acids a viable option. In this review, current preclinical and clinical studies harnessing the potential of antitumoral nucleic acids for GBM treatment will be considered.

Backbone cyclic peptide inhibitors of protein kinase B (PKB/Akt).

Elevated levels of activated protein kinase B (PKB/Akt) have been detected in many types of cancer. Substrate-based peptide inhibitors have the advantage of selectivity due to their extensive interactions with the kinase-specific substrate binding site but often lack necessary pharmacological properties. Chemical modifications of potent peptide inhibitors, such as cyclization, may overcome these drawbacks while maintaining potency.

Microwave-assisted solid-phase aza-peptide synthesis: aza scan of a PKB/Akt inhibitor using aza-arginine and aza-proline precursors.

Aza-peptides are peptidomimetics in which one or more of the α-carbons, bearing the side-chain residues, has been replaced by a nitrogen. These peptidomimetics have been shown to be promising for the generation of drug leads and for structure-activity relationship studies. Aza-scan is the systematic replacement of amino acid residues in a given peptide with their aza counterparts.

Contribution of gross chromosomal changes to HPV16-induced transformation.

Cervical cancer is initiated by infection with high-risk human papillomavirus (HPV). The viral E6 and E7 oncogenes are required for the initiation of cervical epithelial cell immortalization, but do not suffice to cause cervical cancer. Human oncogenes and tumor suppressor genes with altered activity in cervical carcinoma have been recognized, but none of these appears to be an absolute precondition for the development of the cancer.

Up-regulation of AMP-activated protein kinase in cancer cell lines is mediated through c-Src activation.

We report that the activation level of AMP-dependent protein kinase AMPK is elevated in cancer cell lines as a hallmark of their transformed state. In OVCAR3 and A431 cells, c-Src signals through protein kinase Cα, phospholipase Cγ, and LKB1 to AMPK. AMPK controls internal ribosome entry site (IRES) dependent translation in these cells.

Amino acid starvation sensitizes cancer cells to proteasome inhibition.

We explored the crosstalk between protein degradation and synthesis in cancer cells. The tumorigenic cell line, MCF7, showed enhanced proteasome activity compared to the nontumorigenic line, MCF10A. Although there was no difference in the sensitivity of MCF7 and MCF10A cells to proteasome inhibition in complete growth medium, combining proteasome inhibition with amino acid deprivation led to reduced protein synthesis and survival of MCF7 cells, with a lesser effect on MCF10A cells.

Signal transduction therapy of cancer.

Signal transduction therapy for cancer targets signaling elements with key roles in cancer cell survival and proliferation, but with more minor roles in the survival of healthy cells. Cancer cells have shrunken signaling networks, and therefore tend to be dependent on fewer signaling modules than non-cancerous cells. Thus, targeted therapy holds the promise of efficacy with minimal toxicity.

Synthesis and structure-activity relationship studies of peptidomimetic PKB/Akt inhibitors: the significance of backbone interactions.

Elevated levels of activated Protein Kinase B (PKB/Akt) have been detected in many types of human cancer. In contrast to ATP site inhibitors, substrate-based inhibitors are more likely to be selective because of extensive interactions with the specific substrate binding site. Unfortunately, peptide-based inhibitors lack important pharmacological properties that are required of drug candidates.

Novel method for the synthesis of urea backbone cyclic peptides using new Alloc-protected glycine building units.

Cyclization of bioactive peptides, utilizing functional groups serving as natural pharmacophors, is often accompanied with loss of activity. The backbone cyclization approach was developed to overcome this limitation and enhance pharmacological properties. Backbone cyclic peptides are prepared by the incorporation of special building units, capable of forming amide, disulfide and coordinative bonds.

Shift from apoptotic to necrotic cell death during human papillomavirus-induced transformation of keratinocytes.

Oncogenic transformation is a complex, multistep process, which goes through several stages before complete malignant transformation occurs. To identify early processes in carcinogenesis, we used an in vitro model, based on the initiating event in cervical cancer, papillomavirus transformation of keratinocytes. We compared gene expression in primary keratinocytes (K) and papillomavirus-transformed keratinocytes from early (E) and late (L) passages and from benzo[a]pyrene-treated L cells (BP).

Targeting the EGFR and the PKB pathway in cancer.

The EGFR and PKB pathways are frequently activated in cancer, so are prime targets for cancer therapy. To this end, new inhibitors are being tested. EGFR inhibitors as single therapy have little benefit, although therapies that evoke an antitumor immune response are more effective.

Optimization of energy-consuming pathways towards rapid growth in HPV-transformed cells.

Cancer is a complex, multi-step process characterized by misregulated signal transduction and altered metabolism. Cancer cells divide faster than normal cells and their growth rates have been reported to correlate with increased metabolic flux during cell transformation. Here we report on progressive changes in essential elements of the biochemical network, in an in vitro model of transformation, consisting of primary human keratinocytes, human keratinocytes immortalized by human papillomavirus 16 (HPV16) and passaged repeatedly in vitro, and the extensively-passaged cells subsequently treated with the carcinogen benzo[a]pyrene.

Targeted cancer therapy: promise and reality.

Signal transduction therapy for cancer targets specific molecular elements that are essential for survival of the tumor. Gleevec has a profound effect on early phase chronic myeloid leukemia because it inhibits the major driving factor of the tumor, BCR-ABL. Almost all other cancers depend on several factors, and blocking a single signal transduction factor is largely ineffective.

Killing time for cancer cells.

As the signalling pathways that control cellular proliferation and death are unravelled, a range of targets have emerged as candidates for molecular cancer therapy. For their survival, cancer cells depend on a few highly activated signalling pathways; inhibition of these pathways has a strong apoptotic effect and can lead to tumour regression. But drugs that exploit this weakness, such as imatinib, have not cured patients: withdrawal of the drug leads to disease recurrence, and sustained treatment leads to the emergence of drug-resistant clones.