Infection, mutation, and cancer evolution

An Overview of Cancer Biology, Pathophysiological Development and It's Treatment Modalities: Current Challenges of Cancer anti-Angiogenic Therapy

A number of conditions and factors can cause the transformation of normal cells in the body into malignant tissue by changing the normal functions of a wide range of regulatory, apoptotic, and signal transduction pathways. Despite the current deficiency in fully understanding the mechanism of cancer action accurately and clearly, numerous genes and proteins that are causally involved in the initiation, progression, and metastasis of cancer have been identified. But due to the lack of space and the abundance of details on this complex topic, we have emphasized here more recent advances in our understanding of the principles implied tumor cell transformation, development, invasion, angiogenesis, and metastasis. Inhibition of angiogenesis is a significant strategy for the treatment of various solid tumors, that essentially depend on cutting or at least limiting the supply of blood to micro-regions of tumors, leading to pan-hypoxia and pan-necrosis inside solid tumor tissues. Researchers have continued to enhance the efficiency of anti-angiogenic drugs over the past two decades, to identify their potential in the drug interaction, and to discover reasonable interpretations for possible resistance to treatment. In this review, we have discussed an overview of cancer history and recent methods use in cancer therapy, focusing on anti-angiogenic inhibitors targeting angiogenesis formation. Further, this review has explained the molecular mechanism of action of these anti-angiogenic inhibitors in various tumor types and their limitations use. In addition, we described the synergistic mechanisms of immunotherapy and anti-angiogenic therapy and summarizes current clinical trials of these combinations. Many phase III trials found that combining immunotherapy and anti-angiogenic therapy improved survival. Therefore, targeting the source supply of cancer cells to grow and spread with new anti-angiogenic agents in combination with different conventional therapy is a novel method to reduce cancer progression. The aim of this paper is to overview the varying concepts of cancer focusing on mechanisms involved in tumor angiogenesis and provide an overview of the recent trends in anti-angiogenic strategies for cancer therapy.

Modeling cancer's ecological and evolutionary dynamics

In this didactic paper, we present a theoretical modeling framework, called the G-function, that integrates both the ecology and evolution of cancer to understand oncogenesis. The G-function has been used in evolutionary ecology, but has not been widely applied to problems in cancer. Here, we build the G-function framework from fundamental Darwinian principles and discuss how cancer can be seen through the lens of ecology, evolution, and game theory. We begin with a simple model of cancer growth and add on components of cancer cell competition and drug resistance. To aid in exploration of eco-evolutionary modeling with this approach, we also present a user-friendly software tool. By the end of this paper, we hope that readers will be able to construct basic G function models and grasp the usefulness of the framework to understand the games cancer plays in a biologically mechanistic fashion.

Searching for the Metabolic Signature of Cancer: A Review from Warburg's Time to Now

This review focuses on the evolving understanding that we have of tumor cell metabolism, particularly glycolytic and oxidative metabolism, and traces back its evolution through time. This understanding has developed since the pioneering work of Otto Warburg, but the understanding of tumor cell metabolism continues to be hampered by misinterpretation of his work. This has contributed to the use of the new concepts of metabolic switch and metabolic reprogramming， that are out of step with reality. The Warburg effect is often considered to be a hallmark of cancer, but is it really? More generally, is there a metabolic signature of cancer? We draw the conclusion that the signature of cancer cannot be reduced to a single factor, but is expressed at the tissue level in terms of the capacity of cells to dynamically explore a vast metabolic landscape in the context of significant environmental heterogeneities.

A Review of the Role of Oral Microbiome in the Development, Detection, and Management of Head and Neck Squamous Cell Cancers

The role of the microbiome in the development and propagation of head and neck squamous cell cancer (HNSCC) is largely unknown and the surrounding knowledge lags behind what has been discovered related to the microbiome and other malignancies. In this review, the authors performed a structured analysis of the available literature from several databases. The authors discuss the merits and detriments of several studies discussing the microbiome of the structures of the aerodigestive system throughout the development of HNSCC, the role of the microbiome in the development of malignancies (generally and in HNSCC) and clinical applications of the microbiome in HNSCC. Further studies will be needed to adequately describe the relationship between HNSCC and the microbiome, and to push this relationship into a space where it is clinically relevant outside of a research environment.

Is Chronic Endometritis Associated with Tubal Infertility? A Prospective Cohort Study

STUDY OBJECTIVE

Chronic endometritis (CE), which often presents asymptomatically, is associated with recurrent pregnancy loss, recurrent implantation failure after in vitro fertilization, and endometriosis. Data connecting CE with fallopian tubal occlusion are limited. The aim was to assess a potential association of CE, defined by the presence of syndecan-1 (CD138)-positive plasma cells in endometrial tissue samples, with fallopian tube patency and other factors for infertility, including endometriosis, adenomyosis, and hydrosalpinges.

DESIGN

Prospective, monocentral pilot study.

SETTING

Tertiary care center.

PATIENTS

A cohort of 100 women who were infertile was enrolled from July 2019 to December 2020.

INTERVENTIONS

Hysteroscopy with endometrial biopsy and laparoscopy with chromopertubation.

MEASUREMENTS AND MAIN RESULTS

CE was found in 13 women (13.0%) and was associated with endometriosis (p = .034) and unilateral/bilateral fallopian tube blockage (p = .013). In women with endometriosis, the mean number of CD138-positive cells was positively correlated with the revised American Society for Reproductive Medicine score (r = .302, p = .028). In a binary regression model, the presence of a hydrosalpinx on one or both sides (odds ratio 15.308; 95% confidence interval, 1.637-143.189; p = .017) and the finding of CE in the endometrial tissue sample (odds ratio 5.273; 95% confidence interval, 1.257-22.116; p = .023) were significantly associated with fallopian tubal occlusion.

CONCLUSION

CE was significantly associated with blockage of the fallopian tubes and endometriosis. Endometriosis stage was associated with the number of CD138-positive cells in endometrial biopsies.

Cancer and mosquitoes - An unsuspected close connection

Cancer is a major public health issue and represents a significant burden in countries with different levels of economic wealth. In parallel, mosquito-borne infectious diseases represent a growing problem causing significant morbidity and mortality worldwide. Acknowledging that these two concerns are both globally distributed, it is essential to investigate whether they have a reciprocal connection that can fuel their respective burdens. Unfortunately, very few studies have examined the link between these two threats. This review provides an overview of the possible links between mosquitoes, mosquito-borne infectious diseases and cancer. We first focus on the impact of mosquitoes on carcinogenesis in humans including the transmission of oncogenic pathogens through mosquitoes, the immune reactions following mosquito bites, the presence of non-oncogenic mosquito-borne pathogens, and the direct transmission of cancer cells. The second part of this review deals with the direct or indirect consequences of cancer in humans on mosquito behaviour. Thirdly, we discuss the potential impacts that natural cancers in mosquitoes can have on their life history traits and therefore on their vector capacity. Finally, we discuss the most promising research avenues on this topic and the integrative public health strategies that could be envisioned in this context.

The scope of viral causation of human cancers: interpreting virus density from an evolutionary perspective

Most known oncogenic viruses of humans use DNA as their genomic material. Research over the past quarter century has revealed that their oncogenicity results largely from direct interference with barriers to oncogenesis. In contrast to viruses that have been accepted causes of particular cancers, candidate viral causes tend to have fewer viral than cellular genomes in the tumours. These low viral loads have caused researchers to conclude that the associated viruses are not primary causes of the associated cancers. Consideration of differential survival, reproduction and infiltration of cells in a tumour suggest, however, that viral loads could be low even when viruses are primary causes of cancer. Resolution of this issue has important implications for human health because medical research tends to be effective at preventing and controlling infectious diseases. Mathematical models may clarify the problem and help guide future research by assessing whether low viral loads are likely outcomes of the differential survival, reproduction, and infiltration of cells in a tumour and, more generally, the extent to which viruses contribute to cancer. This article is part of the theme issue 'Silent cancer agents: multi-disciplinary modelling of human DNA oncoviruses'.

DNA viruses and cancer: insights from evolutionary biology

When it comes to understanding the exact mechanisms behind the virus induced cancers, we have often turned to molecular biology. It would be fair to argue that our understanding of cancers caused by viruses has significantly improved since the isolation of Epstein-Barr virus from Burkitt's lymphoma. However they are some important questions that remain unexplored like what advantage do viruses derive by inducing carcinogenesis? Why do viruses code for the so called oncogenes? Why DNA viruses are disproportionately linked to cancers? These questions have been addressed from the lens of evolutionary biology in this review. The evolutionary analysis of virus induced cancer suggests that persistent strategy of infection could be a stable strategy for DNA viruses and also the main culprit behind their tendency to cause cancer. The framework presented in the review not only explains wider observations about cancer caused by viruses but also offers fresh predictions to test the hypothesis.

One-step detection of human papilloma viral infection using quantum dot-nucleotide interaction specificity

Due to the close relationship between carcinogenesis and human papillomavirus (HPV), and since they are transmitted via huge number of asymptomatic carriers, the detection of HPV is really needed to reduce the risk of developing cancer. According to the best of our knowledge, our study provides the very first method for one-step detection of viral infection and if it has initiated the subsequent cancer proliferation. The proposed novel nanosystem consists of magnetic glass particles (MGPs), which were attached with DNA probe on their surface to hybridize with target DNAs. The MGP-probe-DNA hybrid was finally conjugated with CdTe/ZnSe core/shell quantum dots (QDs). The proposed detection system is based on a novel mechanism in which the MGPs separate out the target DNAs from different biological samples using external magnetic field for better and clear detection and the QDs give different fluorescent maxima for different target DNAs due to their ability to interact differently with different nucleotides. Firstly, the method was optimized using HPV genes cloned into synthetic plasmids. Then it was applied directly on the samples from normal and cancerous cells. After that, the real hospital samples of head and neck squamous cell carcinoma (HNSCC) with or without the infection of HPV were also analyzed. Our novel nano-system is proved successful in detecting and distinguishing between the patients suffering by HPV infection with or without subsequent cancer having detection limit estimated as 1.0 x 10⁹ (GEq/mL). The proposed methodology is faster and cost-effective, which can be applied at the clinical level to help the doctors to decide the strategy of medication that may save the life of the patients with an early treatment.

Genetic diversity, inbreeding and cancer

Genetic diversity is essential for adaptive capacities, providing organisms with the potential of successfully responding to intrinsic and extrinsic challenges. Although a clear reciprocal link between genetic diversity and resistance to parasites and pathogens has been established across taxa, the impact of loss of genetic diversity by inbreeding on the emergence and progression of non-communicable diseases, such as cancer, has been overlooked. Here we provide an overview of such associations and show that low genetic diversity and inbreeding associate with an increased risk of cancer in both humans and animals. Cancer being a multifaceted disease, loss of genetic diversity can directly (via accumulation of oncogenic homozygous mutations) and indirectly (via increased susceptibility to oncogenic pathogens) impact abnormal cell emergence and escape of immune surveillance. The observed link between reduced genetic diversity and cancer in wildlife may further imperil the long-term survival of numerous endangered species, highlighting the need to consider the impact of cancer in conservation biology. Finally, the somewhat incongruent data originating from human studies suggest that the association between genetic diversity and cancer development is multifactorial and may be tumour specific. Further studies are therefore crucial in order to elucidate the underpinnings of the interactions between genetic diversity, inbreeding and cancer.

Paradoxes of tumour complexity: somatic selection, vulnerability by design, or infectious aetiology?

The aetiology of cancer involves intricate cellular and molecular mechanisms that apparently emerge on the short timescale of a single lifetime. Some of these traits are remarkable not only for their complexity, but also because it is hard to conceive selection pressures that would favour their evolution within the local competitive microenvironment of the tumour. Examples include 'niche construction' (re-programming of tumour-specific target sites) to create permissive conditions for distant metastases; long-range feedback loops of tumour growth; and remarkably 'plastic' phenotypes (e.g. density-dependent dispersal) associated with metastatic cancer. These traits, which we term 'paradoxical tumour traits', facilitate the long-range spread or long-term persistence of the tumours, but offer no apparent benefit, and might even incur costs in the competition of clones within the tumour. We discuss three possible scenarios for the origin of these characters: somatic selection driven by specific selection regimes; non-adaptive emergence due to inherent vulnerabilities in the organism; and manipulation by putative transmissible agents that contribute to and benefit from these traits. Our work highlights a lack of understanding of some aspects of tumour development, and offers alternative hypotheses that might guide further research.

Short- and long-term evolution in our arms race with cancer: Why the war on cancer is winnable

Human society is engaged in an arms race against cancer, which pits one evolutionary process-human cultural evolution as we develop novel cancer therapies-against another evolutionary process-the ability of oncogenic selection operating among cancer cells to select for lineages that are resistant to our therapies. Cancer cells have a powerful ability to evolve resistance over the short term, leading to patient relapse following an initial period of apparent treatment efficacy. However, we are the beneficiaries of a fundamental asymmetry in our arms race against cancer: Whereas our cultural evolution is a long-term and continuous process, resistance evolution in cancer cells operates only over the short term and is discontinuous - all resistance adaptations are lost each time a cancer patient dies. Thus, our cultural adaptations are permanent, whereas cancer's genetic adaptations are ephemeral. Consequently, over the long term, there is good reason to expect that we will emerge as the winners in our war against cancer.

Ancient cancers and infection-induced oncogenesis

Cancers have been reported in bone and soft tissue of ancient agricultural populations. Fossilized bones from prehistoric periods provide evidence of tumors but only one example of cancer. Difficulties in diagnosing the causes of lesions in mummified tissue and fossilized bone, and in interpreting the prevalence of cancers from remains, draw attention to the need for complementary approaches to assess the occurrence of cancer in ancient populations. This paper integrates current knowledge about pathogen induction of cancer with phylogenetic analyses of oncogenic pathogens, and concludes that pathogen-induced cancers were probably generally present in ancient historic and prehistoric human populations. Consideration of cancers in extant human populations and wildlife lends credence to this conclusion, with the caveat that the presence of cancers may depend on population-specific exposures to oncogenic parasites and carcinogens.

The Hypertension Pandemic: An Evolutionary Perspective

Hypertension affects over 1.2 billion individuals worldwide and has become the most critical and expensive public health problem. Hypertension is a multifactorial disease involving environmental and genetic factors together with risk-conferring behaviors. The cause of the disease is identified in ∼10% of the cases (secondary hypertension), but in 90% of the cases no etiology is found (primary or essential hypertension). For this reason, a better understanding of the mechanisms controlling blood pressure in normal and hypertensive patients is the aim of very active experimental and clinical research. In this article, we review the importance of the renin-angiotensin-aldosterone system (RAAS) for the control of blood pressure, focusing on the evolution of the system and its critical importance for adaptation of vertebrates to a terrestrial and dry environment. The evolution of blood pressure control during the evolution of primates, hominins, and humans is discussed, together with the role of common genetic factors and the possible causes of the current hypertension pandemic in the light of evolutionary medicine.

Infections and cancer: the "fifty shades of immunity" hypothesis

BACKGROUND

Since the beginning of the twentieth century, infection has emerged as a fundamental aspect of cancer causation with a growing number of pathogens recognized as oncogenic. Meanwhile, oncolytic viruses have also attracted considerable interest as possible agents of tumor destruction.

DISCUSSION

Lost in the dichotomy between oncogenic and oncolytic agents, the indirect influence of infectious organisms on carcinogenesis has been largely unexplored. We describe the various ways - from functional aspects to evolutionary considerations such as modernity mismatches - by which infectious organisms could interfere with oncogenic processes through immunity. Finally, we discuss how acknowledging these interactions might impact public health approaches and suggest new guidelines for therapeutic and preventive strategies both at individual and population levels. Infectious organisms, that are not oncogenic neither oncolytic, may play a significant role in carcinogenesis, suggesting the need to increase our knowledge about immune interactions between infections and cancer.

Infection and cancer in multicellular organisms

Evolutionary considerations suggest that oncogenic infections should be pervasive among animal species. Infection-associated cancers are well documented in humans and domestic animals, less commonly reported in undomesticated captive animals, and rarely documented in nature. In this paper, we review the literature associating infectious agents with cancer to evaluate the reasons for this pattern. Non-malignant infectious neoplasms occur pervasively in multicellular life, but oncogenic progression to malignancy is often uncertain. Evidence from humans and domestic animals shows that non-malignant infectious neoplasms can develop into cancer, although generally with low frequency. Malignant neoplasms could be difficult to find in nature because of a low frequency of oncogenic transformation, short survival after malignancy and reduced survival prior to malignancy. Moreover, the evaluation of malignancy can be ambiguous in nature, because criteria for malignancy may be difficult to apply consistently across species. The information available in the literature therefore does not allow for a definitive assessment of the pervasiveness of infectious cancers in nature, but the presence of infectious neoplasias and knowledge about the progression of benign neoplasias to cancer is consistent with a widespread but largely undetected occurrence.

On the apparent rarity of epithelial cancers in captive chimpanzees

Malignant neoplasms arising from epithelial cells are called carcinomas. Such cancers are diagnosed in about one in three humans in 'developed' countries, with the most common sites affected being lung, breast, prostate, colon, ovary and pancreas. By contrast, carcinomas are said to be rare in captive chimpanzees, which share more than 99% protein sequence homology with humans (and possibly in other related 'great apes'-bonobos, gorillas and orangutans). Simple ascertainment bias is an unlikely explanation, as these nonhuman hominids are recipients of excellent veterinary care in research facilities and zoos, and are typically subjected to necropsies when they die. In keeping with this notion, benign tumours and cancers that are less common in humans are well documented in this population. In this brief overview, we discuss other possible explanations for the reported rarity of carcinomas in our closest evolutionary cousins, including inadequacy of numbers surveyed, differences in life expectancy, diet, genetic susceptibility, immune responses or their microbiomes, and other potential environmental factors. We conclude that while relative carcinoma risk is a likely difference between humans and chimpanzees (and possibly other 'great apes'), a more systematic survey of available data is required for validation of this claim.

Cancer and life-history traits: lessons from host-parasite interactions

Despite important differences between infectious diseases and cancers, tumour development (neoplasia) can nonetheless be closely compared to infectious disease because of the similarity of their effects on the body. On this basis, we predict that many of the life-history (LH) responses observed in the context of host-parasite interactions should also be relevant in the context of cancer. Parasites are thought to affect LH traits of their hosts because of strong selective pressures like direct and indirect mortality effects favouring, for example, early maturation and reproduction. Cancer can similarly also affect LH traits by imposing direct costs and/or indirectly by triggering plastic adjustments and evolutionary responses. Here, we discuss how and why a LH focus is a potentially productive but under-exploited research direction for cancer research, by focusing our attention on similarities between infectious disease and cancer with respect to their effects on LH traits and their evolution. We raise the possibility that LH adjustments can occur in response to cancer via maternal/paternal effects and that these changes can be heritable to (adaptively) modify the LH traits of their offspring. We conclude that LH adjustments can potentially influence the transgenerational persistence of inherited oncogenic mutations in populations.

Cancer: an emergent property of disturbed resource-rich environments? Ecology meets personalized medicine

For an increasing number of biologists, cancer is viewed as a dynamic system governed by evolutionary and ecological principles. Throughout most of human history, cancer was an uncommon cause of death and it is generally accepted that common components of modern culture, including increased physiological stresses and caloric intake, favor cancer development. However, the precise mechanisms for this linkage are not well understood. Here, we examine the roles of ecological and physiological disturbances and resource availability on the emergence of cancer in multicellular organisms. We argue that proliferation of 'profiteering phenotypes' is often an emergent property of disturbed, resource-rich environments at all scales of biological organization. We review the evidence for this phenomenon, explore it within the context of malignancy, and discuss how this ecological framework may offer a theoretical background for novel strategies of cancer prevention. This work provides a compelling argument that the traditional separation between medicine and evolutionary ecology remains a fundamental limitation that needs to be overcome if complex processes, such as oncogenesis, are to be completely understood.

Joint infectious causation of human cancers

Joint infectious causation of cancer has been accepted in a few well-studied instances, including Burkitt's lymphoma and liver cancer. In general, evidence for the involvement of parasitic agents in oncogenesis has expanded, and recent advances in the application of molecular techniques have revealed specific mechanisms by which host cells are transformed. Many parasites evolve to circumvent immune-mediated detection and destruction and to control critical aspects of host cell reproduction and survival: cell proliferation, apoptosis, adhesion, and immortalization. The host has evolved tight regulation of these cellular processes-the control of each represents a barrier to cancer. These barriers need to be compromised for oncogenesis to occur. The abrogation of a barrier is therefore referred to as an essential cause of cancer. Alternatively, some aspects of cellular regulation restrain but do not block oncogenesis. Relaxation of a restraint is therefore referred to as an exacerbating cause of cancer. In this chapter, we explore past and current evidence for joint infectious causation of cancer in the context of essential and exacerbating causes. We stress that discovery of joint infectious causation may provide great improvements in controlling cancer, particularly through the identification of many additional nonhuman targets for synergistic interventions for prevention and treatment.

A phylogenetic model for understanding the effect of gene duplication on cancer progression

As biotechnology advances rapidly, a tremendous amount of cancer genetic data has become available, providing an unprecedented opportunity for understanding the genetic mechanisms of cancer. To understand the effects of duplications and deletions on cancer progression, two genomes (normal and tumor) were sequenced from each of five stomach cancer patients in different stages (I, II, III and IV). We developed a phylogenetic model for analyzing stomach cancer data. The model assumes that duplication and deletion occur in accordance with a continuous time Markov Chain along the branches of a phylogenetic tree attached with five extended branches leading to the tumor genomes. Moreover, coalescence times of the phylogenetic tree follow a coalescence process. The simulation study suggests that the maximum likelihood approach can accurately estimate parameters in the phylogenetic model. The phylogenetic model was applied to the stomach cancer data. We found that the expected number of changes (duplication and deletion) per gene for the tumor genomes is significantly higher than that for the normal genomes. The goodness-of-fit test suggests that the phylogenetic model with constant duplication and deletion rates can adequately fit the duplication data for the normal genomes. The analysis found nine duplicated genes that are significantly associated with stomach cancer.

Toward a general evolutionary theory of oncogenesis

We propose an evolutionary framework, the barrier theory of cancer, which is based on the distinction between barriers to oncogenesis and restraints. Barriers are defined as mechanisms that prevent oncogenesis. Restraints, which are more numerous, inhibit but do not prevent oncogenesis. Processes that compromise barriers are essential causes of cancer; those that interfere with restraints are exacerbating causes. The barrier theory is built upon the three evolutionary processes involved in oncogenesis: natural selection acting on multicellular organisms to mold barriers and restraints, natural selection acting on infectious organisms to abrogate these protective mechanisms, and oncogenic selection which is responsible for the evolution of normal cells into cancerous cells. The barrier theory is presented as a first step toward the development of a general evolutionary theory of cancer. Its attributes and implications for intervention are compared with those of other major conceptual frameworks for understanding cancer: the clonal diversification model, the stem cell theory and the hallmarks of cancer. The barrier theory emphasizes the practical value of distinguishing between essential and exacerbating causes. It also stresses the importance of determining the scope of infectious causation of cancer, because individual pathogens can be responsible for multiple essential causes in infected cells.