Cutting Edge Therapies for Cancer in the 21st Century

Caveolae are flask-shaped plasma membrane invaginations that represent a subset of the well-known lipid raft. These organelles are characterized by the presence of the caveolin-1 (Cav-1) protein that plays an important role in the regulation of several signal transduction pathways. More than ten years ago, in vitro experiments showed that downregulation of Cav-1 drives cell transformation and hyperactivation of the Ras-p42/44 MAP kinase cascade. In addition, it was shown that Cav-1 functions as a repressor of cyclin D1, possibly explaining its tumor suppressor activity in cultured cells. Later on, in vivo experiments showed that Cav-1 was involved in tumor development. In particular, the absence of Cav-1 in mouse skin increased the susceptibility to carcinogen-induced epidermal hyperplasia and tumor formation. Moreover, loss of Cav-1 expression caused the development of dysplastic mammary lesions in tumor-prone transgenic mice where cyclin D1 expression levels were dramatically elevated. These studies were the first in vivo demonstrations showing that caveolin-1 could function as a tumor suppressor gene. However, other investigators have shown that certain cancer cells show up-regulation of caveolin-1 that results in more metastatic and aggressive tumor like in bladder, thyroid, and prostate carcinomas. Taken together, these data suggest that Cav-1 is implicated in both tumor suppression and oncogenesis.

The pattern of gene expression can vary in each cell without changes in the DNA sequence. This is accomplished by reversible chemical modifications of the chromatin, which are generally indicated with the term “epigenetics”. Chromatin remodeling caused by DNA methylation and histone modifications, especially at the site of genes promoters, are the major epigenetic events enabling transcriptional regulation. It is known that alterations of epigenetic signals are important early events for cancer development. These changes profoundly influence gene expression and are at the basis of malignant transformation. Specific pathways of genes are proficiently turned on or off by cancer cells to achieve uncontrolled proliferation. Genes playing key roles in DNA damage responses, apoptosis signaling and DNA repair are in fact frequently silenced by epigenetic modifications, while those involved in cell proliferation are often overexpressed. But the appealing feature of epigenetic changes is that they can be potentially reverted. This peculiarity has opened the way to new therapeutic possibilities to fight tumors that might be collectively termed “epigenetic therapy”. Here we will discuss the basic aspects of epigenetic alterations, and in particular those events involving critical genes implicated in carcinogenesis, and the current relevance of DNA methyltransferase and histone deacetylase inhibitors for cancer therapy.

The discovery of x-rays by Wilhelm Conrad Roentgen and natural radiation by Henry Becquerel and Marie and Pierre Curie at the end of the 19th century was the cornerstone for the development of a new discipline: Radiology. Soon after the discovery of radiation, its diagnostic and therapeutic applications became evident and for more than 100 years it has been utilized in the diagnosis and treatment of cancer. During the last three decades the invention of computerized tomography, magnetic resonance and the development of fractionated therapy have improved planning and provided more accurate dosing. The current radiation techniques are capable of delivering more individualized treatment with less harm to normal adjacent tissue; therefore, more patients are treated with some form of radiation. Current radiation treatment planning modalities include three-dimensional conformational radiation therapy (3D-CRT), which accounts for tumor volume to approximate the radiation beam to the shape of the tumor; intensity-modulated radiation therapy (IMRT), a more advanced form of 3D-CRT, which utilizes varying intensities of radiation beams to produce dosage distributions that are more precise than with 3D-CRT; and fourdimensional radiation therapy (4D-RT) which not only accounts for volume and tumor shape but also considers patient and organ motion. Radiation treatment modalities can be divided into external beam radiation treatment, brachytherapy, and targeted radiotherapy. This chapter will focus on the historical events that have led to the current progress in radiation therapy, the generation of therapeutic radiation, mode of action, current radiation planning and treatment modalities, and side effects.

Interferons (IFNs) are a family of cytokines with several biological functions. Currently, IFNs are classified in three groups: Type I, Type II and Type III. Type I IFNs include a family of several related proteins produced by essentially all eukaryotic cells. Type II IFN has only one member, IFN-, is mainly produced by T cells, NK cells and NKT cells. Type III IFNs include 3 related proteins, IFN-1/IL-29, IFN-2/IL-28A and IFN-3/IL28B, which are produced by several cells types. IFNs exhibit antiviral, antiproliferative, immune-modulatory and anti-angiogenic properties. Their potent antiproliferative effects make them good candidates for cancer therapy. Type II and type III IFNs have been investigated mainly in cancer cell lines and in animal models. Several clinical trials have been conducted with type I IFNs; the results of some of them have led to the approval and use of this type of IFN for the treatment of some malignancies. However, many patients develop toxicity and this has limited their use as anticancer agents, making it necessary to find a way to determine the patients who would most likely benefit from IFN treatment to avoid exposing non responsive patients to its toxic effects. In this chapter the mechanism of IFN production and signaling and their use in different types of cancer will be addressed.

Radiation therapy is among the most common and effective therapies employed in both curative and palliative management of cancer patients. About 50% of all patients diagnosed with localized malignant tumors are treated with radiation, usually high-energy X-rays, as a part of the initial cancer therapy. Many years ago, it was proposed that high-energy ions might be successfully employed in the treatment of localized tumors, owing their physical and biological advantages toward X-rays. Indeed, high-energy charged particles are characterized by a more favorable tissue depth-dose distribution and higher relative biological effectiveness (RBE) compared with X-rays. Currently, many facilities in the U.S.A., Europe, and Japan use highenergy protons and carbon ions for the treatment of solid tumors and several new centers are under construction. These types of therapies present very high costs due to the expensive technologies used in building accelerators and for beam delivery. Therefore, the debate on cost: benefit ratio of these techniques is ongoing, although strong evidence suggests that charged particle therapy provides an important clinical advantage in treatment of localized tumors. In this chapter, we will describe clinical applications and results of charged particle radiotherapy compared to X-rays, and identify and discuss important questions that need to be addressed in this field.

In this chapter, the impact of lipid molecules on hematopoiesis will be reviewed in a format friendly to those outside the field. The focus of the review is on how dietary fatty acids impact hematopoiesis through changes in differentiation. We begin with a discussion of general hematopoiesis including the concepts of stem and progenitor cells that drive hematopoiesis and the various cell types they produce. We then will discuss the principles of epigenetic gene regulation and differentiation pertinent to hematopoietic stem and progenitor cells. Once these principles have been introduced, we will examine how dietary lipids can impact hematopoietic differentiation. The relationship of epigenetics and dietary lipids to leukemic and preleukemic states will also be explored. We will conclude with a look at how WNT signaling can impact hematopoiesis through epigenetic gene regulation, dietary lipids, and differentiation.

Prostate cancer (PCa) is the third leading cause of cancer death in the US. It is a heterogeneous disease with clinical course ranging from indolent disease to rapidly progressing, often fatal disease. Complex molecular mechanisms lead to development of metastatic castrate-resistant prostate cancer (CRPC) for which no curative therapies exist. There is an urgent need to develop rational biomarkers and therapeutic targets that will help expedite discovery of curative therapies. This chapter describes the treatment options for localized and metastatic PCa and provides an in-depth review of the Jak2/Stat5a/b signaling pathway in PCa, which is critical in prostate cancer progression, development of castrate-resistance and metastases. Target validation of Jak2/Stat5a/b pathway is discussed in detail, including the role of pharmacological inhibitors of Jak2 and Stat5a/b, providing a strong rationale for targeting this pathway to improve outcomes in PCa. Furthermore, the prognostic and predictive significance of Stat5a/b in providing personalized therapy in PCa is reviewed as well.

The existence of a crosstalk between the androgen receptor (AR) pathway and interleukin-6 (IL-6) signaling in prostate cancer (PCa) is broadly recognized. IL-6 activates the AR in a ligand-independent manner leading to the transcription of prostatespecific antigen (PSA), the most widely used marker for the detection and monitoring of PCa. IL-6 expression is increased in the malignant epithelium of prostate cancer patients and its levels are enhanced in the plasma of patients with late-stage disease. Interestingly, IL-6 is able to shift from being a paracrine growth inhibitor to an autocrine growth stimulator in PCa cells. Hence, IL-6 has been implicated in the progression towards castration-resistant prostate cancer (CRPC), in which elevated levels are indicative of poor prognosis and predict resistance to chemotherapy with taxanes. We will depict here the IL-6 signaling pathway and its contribution to PCa. For this purpose, we will portray the molecular events that prompted the origin of LNCaPIL- 6+ cells, a model of advanced PCa, upon chronic exposure to IL-6. We will also examine the similarities between LNCaP-IL-6+ cells and late-stage prostatic carcinoma. In addition, we will reveal the effect of CNTO 328, a chimeric monoclonal antibody targeting IL-6, in LNCaP-IL-6+ cells, as well as discuss the latest results from clinical trials with CNTO 328 in CRPC patients. Finally, we will speculate on the possibility, not yet investigated, of administering CNTO 328 to patients before the onset of CRPC.

Gastric cancer is still one of the prevalent leading causes of cancer-related deaths worldwide. The high mortality rate is mainly due to late-stage diagnosis, which has a very poor prognosis (five-year survival rates are as little as 3-10%). By contrast, early stage gastric cancer is highly curable with five-year survival rates exceeding 90%. Early detection is therefore the single most important factor influencing the outcome for gastric cancer patients. However, there are currently no biomarkers of acceptable sensitivity and specificity to detect early stage gastric cancer. Gastric infection with Helicobacter pylori (H. pylori) seems to be a risk factor for gastric cancer. Epidemiological studies have shown that patients that test serum positive to H. pylori infection are associated with a three- to six-fold increase in the risk of gastric cancer, findings that are compatible with pathological links between H. pylori-associated gastritis, pre-cancerous lesions, and subsequent cancer of the stomach. In a previous study, moving from genomic to proteomic investigation, we have identified a protein, gastrokine 1 (GKN1), a stomach-secreted protein previously named AMP-18 (18kDa Antrum Mucosa Protein) that was highly expressed in normal tissues and significantly down-regulated in H. pylori positive patients with respect to H. pylori negative subjects. In addition, we have also found that GKN1 is normally expressed in gastric mucosa but not in primary tumours, both at the transcriptional and translational levels. On the basis of these findings, we propose that GKN1 can be used as a new molecular marker that could be useful to predict early cell transformation and might be a potential novel target for gastric cancer therapeutics. Moreover, we have also found that recombinant GKN1 affect cancer cell growth and that the transient expression of GKN1 in human gastric cancer also inhibits cell growth and induces apoptosis, thus suggesting the importance of GKN1 in preventing cancer development in gastric tissues. Finally, we hypothesize that GKN1 might act as a tumor suppressor and thus foresee its importance as an antitumor drug.

Nuclear medicine imaging and treatment play a particularly prominent role in the management of Neuroendocrine Tumours (NET), consistently pertaining to the molecular level on the ground of specific properties of neuroendocrine neoplastic cells. NET may be sporadic or appear as part of an inherited syndrome, originate from the diffuse neuroendocrine system and consist of Amine Precursor Uptake and Decarboxylation (APUD) cells; these cells produce and store hormones which account for a broad spectrum of subsequent clinical manifestations. NET cells also characteristically overexpress specific cell membrane peptide receptors like somatostatin receptors (sstr). Clinically non-functional NET contribute further to their relatively common delayed diagnosis.

Histologic assessment with relative immunohistochemical indices, remains the gold standard for NET diagnosis. Measurement of serum or urinary, specific or non-specific, hormonal markers, aids in the diagnostic NET investigation, with high sensitivity, in addition to follow-up and possibly prognostic value. Involved localization modalities include endoscopic ultrasound (ΕUS), computerized tomography (CT), magnetic resonance imaging (MRI) and radionuclide methods.

Nuclear imaging exploits radiopharmaceuticals similar in molecular structure to the tumour-synthesized substances or incorporated into various tumour cellular metabolic processes, to selectively visualize NET. Established scintigraphic studies on primary and metastatic NET imaging, apply radiolabelled synthetic somatostatin (sst) analogues [like indium-111-diethylene triamine pentaacetic acid-octreotide (¹¹¹Ιn-DTPAoctreotide)] to bind on sstr, iodine-131/123 meta-iodo-benzylguanidine (^131/123I-MIBG) to be actively transported and stored within neurosecretory granules of APUD cells as a chemical nor-epinephrine analogue, and pentavalent technetium-99m dimercaptosuccinic acid [^99mTc(V)-DMSA] to be taken up by cells exhibiting accelerated proliferation. Positron emission tomography (PET) or PET/CT studies are also helpful for NET evaluation, by employing ⁶⁸Ga-labelled sst analogues such as [⁶⁸Ga-DOTA⁰,Tyr³]octreotide (⁶⁸Ga-DOTATOC), [⁶⁸Ga-DOTA⁰,Tyr³]octreotate (⁶⁸Ga- DOTATATE) and ⁶⁸Ga-DOTANOC for sstr binding, ¹⁸F-DOPA, ¹¹C-5-HTP and ¹¹Chydroxyephedrine (¹¹C-HED) for APUD mechanism exploitation, and ¹⁸F-FDG-PET for NET of low-differentiation and high proliferative activity. The traditional whole-body bone scan with ^99mTc-methylene diphosphonate (^99mTc-MDP) adds to staging and prognostic data through the identification of skeletal metastases. Altogether, in patients bearing NET, radionuclide imaging provides non-invasive diagnosis, staging, restaging, treatment planning, prediction of therapy response, selection of patients for targeted (radio- or non-radiolabelled) therapy, and follow-up for detection of relapse or disease progression.

The primary objective of cancer classification is to predict a patient’s response to a panel of treatment modalities, thereby guiding the development of a rational therapy and optimizing therapeutic success. However, traditional staging methods used to classify oral squamous cell carcinoma (OSCC) are marginally effective in predicting clinical outcomes. Emerging data and increasingly refined and costeffective high-throughput technologies have the potential to advance oral cancer classification and treatment beyond the empiric towards a more molecularly-defined, individualized approach. Yet, despite an increasing appreciation of the diverse genomic, proteomic and epigenetic aberrations associated with OSCC, the promise of basing OSCC treatment decisions on molecular biomarkers has yet to be realized. Herein, we highlight a few specific examples of well-studied or intriguing prognostic biomarkers, and include a brief review of high-throughput technologies that have been used in the study of OSCC, and that could emerge as critical tools in the prediction of OSCC prognosis and in the design of novel oral cancer therapeutics. In the age of molecular therapeutics and personalized cancer medicine, this is likely to take the form of drugs or other compounds targeted to specific proteins or other cellular components, and with a minimal side effect profile.

Omega-3 (n-3) and omega-6 (n-6) polyunsaturated fatty acids (FAs) are essential fats that must be obtained from the diet. The typical western diet is heavily weighted towards n-6 FAs with little n-3 intake. Recently, numerous studies have suggested that arachidonic acid (AA), an n-6 FA, and its metabolites have a significant role in tumor promotion. Inversely, n-3 fatty acids have consistently been shown to slow the growth and increase the chemo-sensitivity of various malignancies in vitro and in vivo. Clinical studies utilizing n-3 as adjuvants to therapy have shown much promise. The purpose of this chapter is to provide an overview of n-3 and n-6 fatty acids and their application to cancer. In this chapter we will be focusing on 1) the metabolism of n-3 and n-6 FA, 2) the mechanisms of action and implications in cancer and 3) the application of n-3 as promising therapies for the treatment of cancer.

The field of ultrasound has expanded since the discovery of ultrasound contrast agents (UCAs) from diagnostics to therapeutic use. UCAs are known as microbubbles (MBs), which can be chemically and physically manipulated to improve their therapeutic potential. MBs can be tailored to bind to specific diseased tissues and act as carriers of different chemo-drugs and genetic materials. These engineered MBs can behave differently to ultrasound intensities resulting in different cavitation methods. Though the underlying mechanism is yet to be fully understood, there is evidence to suggest that mechanical pore formation of cellular membranes allows for the temporary uptake of drugs. The cavitation of MBs can induce temporary and reversible enhancement in the permeability of both individual cells as well as the endothelium including the blood brain barrier. There are too many side-effects and immune responses to current cancer and diseased treatments. MBs protect the immunogenic drugs from eliciting a detrimental response when delivered through the vasculature. They also help reduce the drug dosage by improving drug targeting and drug response. Thus, MBs can be used as vehicles for localized drug delivery and gene therapy allowing us to further develop the potential of curing cancer and other diseases.