THE EXPERIMENTAL DISCLOSURE OF LATENT NEOPLASTIC CHANGES IN TARRED SKIN

Cancer-inducing niche: the force of chronic inflammation

The growth of cancer tissue is thought to be considered driven by a small subpopulation of cells, so-called cancer stem cells (CSCs). CSCs are located at the apex of a hierarchy in a cancer tissue with self-renewal, differentiation and tumorigenic potential that produce the progeny in the tissue. Although CSCs are generally believed to play a critical role in the growth, metastasis, and recurrence of cancers, the origin of CSCs remains to be reconsidered. We hypothesise that, chronic diseases, including obesity and diabetes, establish the cancer-inducing niche (CIN) that drives the undifferentiated/progenitor cells into CSCs, which then develop malignant tumours in vivo. In this context, a CIN could be traced to chronic inflammation that involves long-lasting tissue damage and repair after being exposed to factors such as cytokines and growth factors. This must be distinguished from the cancer microenvironment, which is responsible for cancer maintenance. The concept of a CIN is most important for cancer prevention as well as cancer therapy.

Inflammation and Gastric Cancer

Gastric cancer remains a major killer globally, although its incidence has declined over the past century. It is the fifth most common cancer and the third most common reason for cancer-related deaths worldwide. Gastric cancer is the outcome of a complex interaction between environmental, host genetic, and microbial factors. There is significant evidence supporting the association between chronic inflammation and the onset of cancer. This association is particularly robust for gastrointestinal cancers in which microbial pathogens are responsible for the chronic inflammation that can be a triggering factor for the onset of those cancers. Helicobacter pylori is the most prominent example since it is the most widespread infection, affecting nearly half of the world’s population. It is well-known to be responsible for inducing chronic gastric inflammation progressing to atrophy, metaplasia, dysplasia, and eventually, gastric cancer. This review provides an overview of the association of the factors playing a role in chronic inflammation; the bacterial characteristics which are responsible for the colonization, persistence in the stomach, and triggering of inflammation; the microbiome involved in the chronic inflammation process; and the host factors that have a role in determining whether gastritis progresses to gastric cancer. Understanding these interconnections may improve our ability to prevent gastric cancer development and enhance our understanding of existing cases.

TUMOR CELL MALIGNANCY: A COMPLEX TRAIT BUILT THROUGH RECIPROCAL INTERACTIONS BETWEEN TUMORS AND TISSUE-BODY SYSTEM

Since the discovery of oncogenes and tumor suppressor genes in the late past century, cancer research has been overwhelmingly focused on the genetics and biology of tumor cells and hence has addressed mostly cell-autonomous processes with emphasis on traditional driver/passenger genetic models. Nevertheless, over that same period, multiple seminal observations have accumulated highlighting the role of non-cell autonomous effectors in tumor growth and metastasis. However, given that cell autonomous and non-autonomous events are observed together at the time of diagnosis, it is in fact impossible to know whether the malignant transformation is initiated by cell autonomous oncogenic events or by non-cell autonomous conditions generated by alterations of the tissue-body ecosystem. This review aims at addressing this issue by taking the option of defining malignancy as a complex genetic trait incorporating genetically determined reciprocal interactions between tumor cells and tissue-body ecosystem.

Elastolytic activity is associated with inflammation in bladder cancer

Cancer development and progression is often associated with inflammation. Late diagnosis of inflammation that directly leads to the development of neoplasm - cancer is associated with a reduction in the chance of successful treatment or is associated with therapeutic difficulties. A panel of chromogenic substrates was used for the qualitative determination of specific activity of enzymes in urine of patients with confirmed inflammatory reaction and/or epithelial neoplasms in particular tumors at various stages of development. Urine of people with excluded inflammation was used as a control group. Proteolytic activity was determined in urine samples collected from patients with epithelial neoplasms and/or inflammation. What is more, we determine human neutrophil elastase (HNE) activity related inflammation based on the examination of urine samples. We suspect that the proteolytical activity of urine samples is due to neutrophil response to inflammation, which is directly related to cancer. This is the first study to determine elastolytic activity in bladder cancer urine samples. It supports wider use of urine for inflammation screening.

Bruce Nathan Ames - Paradigm shifts inside the cancer research revolution

Dr. Bruce Ames turned 92 on December 16, 2020. He considers his most recent work linking adequate consumption of 30 known vitamins and minerals with successful aging to be his most important contribution. With the passage of time, it is not uncommon for the accomplishments of a well-known scientist to undergo a parsimonious reductionism in the public mind - Pasteur's vaccine, Mendel's peas, Pavlov's dogs, Ames' test. Those of us in the research generation subsequent to Dr. Ames' are undoubtedly affected by our own unconscious tendencies toward accepting the outstanding achievements of the past as commonplace. In doing so, seminal advances made by earlier investigators are often inadvertently subsumed into common knowledge. But having followed Ames' work since the mid-1970s, we are cognizant that the eponymous Ames Test is but a single chapter in a long and rich narrative. That narrative begins with Ames' classic studies on the histidine operon of Salmonella, for which he was elected to the National Academy of Sciences. A summary of the historical progression of the understanding of chemical carcinogenesis to which Ames and his colleagues contributed is provided. Any summary of a topic as expansive and complex as the ongoing unraveling of the mechanisms underlying chemical carcinogenesis will only touch upon some of the major conceptual advances to which Ames and his colleagues contributed. We hope that scientists of all ages familiar with Ames only through the eponymous Ames Test will further investigate the historical progression of the conceptualization of cancer caused by chemical exposure. As the field of chemical carcinogenesis gradually moves away from primary reliance on animal testing to alternative protocols under the rubric of New Approach Methodologies (NAM) an understanding of where we have been might help to guide where we should go.

Ricerche Sull'Azione Promovente della Follicolina nel Duplice Meccanismo della Carcinogenesi

Studies were undertaken on an eventual initiating or promoting action of follicular hormone in the twofold mechanism of carcinogenesis on the mouse skin. Animals were grouped into two series. The first series was divided into two groups: one was painted with a folliculin oleous solution (Estrene 5) every 3 days, the other with a 5 per cent dilution of croton oil in estrene. The mice of the second series, previously submitted to three paintings with 3:4-benzpyrene, were divided into four groups: 1) control group, 2) painted with Estrene every 3 days, 3) treated with 5 per cent croton oil solution in olive oil, and 4) treated with 5 per cent dilution of croton oil in oleous solution of follicular hormone. Results show that the follicular hormone, either alone or combined with croton oil, fails to produce any initiating and promoting action when painted on mouse skin previously treated with sub-maximal doses of 3:4-benzpyrene. Folliculin, on the contrary, enhances considerably the promoting action of croton oil when painted with it on the skin sensitized with benzpyrene: a rather early appearance of epithelial projections without basal membrane and composed of atypical elements is seen, whereas in animals of the same series, long treated with paintings of croton oil diluted with olive oil or with oleous folliculin this picture is not observed.

Energy metabolic dysfunction as a carcinogenic factor in cancer cells

Cancer, as a leading cause of death, has attracted enormous public attention. Reprogramming of cellular energy metabolism is deemed to be one of the principal hallmarks of cancer. In this article, we reviewed the mutual relationships among environmental pollution factors, energy metabolic dysfunction, and various cancers. We found that most environmental pollution factors could induce cancers mainly by disturbing the energy metabolism. By triggering microenvironment alteration, energy metabolic dysfunction can be treated as a factor in carcinogenesis. Thus, we put forward that energy metabolism might be as a key point for studying carcinogenesis and tumor development to propose new methods for cancer prevention and therapy.

Chronic inflammation and cancer: potential chemoprevention through nuclear factor kappa B and p53 mutual antagonism

Activation of nuclear factor-kappa B (NF- κB) as a mechanism of host defense against infection and stress is the central mediator of inflammatory responses. A normal (acute) inflammatory response is activated on urgent basis and is auto-regulated. Chronic inflammation that results due to failure in the regulatory mechanism, however, is largely considered as a critical determinant in the initiation and progression of various forms of cancer. Mechanistically, NF- κB favors this process by inducing various genes responsible for cell survival, proliferation, migration, invasion while at the same time antagonizing growth regulators including tumor suppressor p53. It has been shown by various independent investigations that a down regulation of NF- κB activity directly, or indirectly through the activation of the p53 pathway reduces tumor growth substantially. Therefore, there is a huge effort driven by many laboratories to understand the NF- κB signaling pathways to intervene the function of this crucial player in inflammation and tumorigenesis in order to find an effective inhibitor directly, or through the p53 tumor suppressor. We discuss here on the role of NF- κB in chronic inflammation and cancer, highlighting mutual antagonism between NF- κB and p53 pathways in the process. We also discuss prospective pharmacological modulators of these two pathways, including those that were already tested to affect this mutual antagonism.

The other side of the coin: the tumor-suppressive aspect of oncogenes and the oncogenic aspect of tumor-suppressive genes, such as those along the CCND-CDK4/6-RB axis

Although cancer-regulatory genes are dichotomized to oncogenes and tumor-suppressor gene s, in reality they can be oncogenic in one situation but tumor-suppressive in another. This dual-function nature, which sometimes hampers our understanding of tumor biology, has several manifestations: (1) Most canonically defined genes have multiple mRNAs, regulatory RNAs, protein isoforms, and posttranslational modifications; (2) Genes may interact at different levels, such as by forming chimeric RNAs or by forming different protein complexes; (3) Increased levels of tumor-suppressive genes in normal cells drive proliferation of cancer progenitor cells in the same organ or tissue by imposing compensatory proliferation pressure, which presents the dual-function nature as a cell-cell interaction. All these manifestations of dual functions can find examples in the genes along the CCND-CDK4/6-RB axis. The dual-function nature also underlies the heterogeneity of cancer cells. Gene-targeting chemotherapies, including that targets CDK4, are effective to some cancer cells but in the meantime may promote growth or progression of some others in the same patient. Redefining "gene" by considering each mRNA, regulatory RNA, protein isoform, and posttranslational modification from the same genomic locus as a "gene" may help in better understanding tumor biology and better selecting targets for different sub-populations of cancer cells in individual patients for personalized therapy.

Marjolin's ulcers: theories, prognostic factors and their peculiarities in spina bifida patients

Background

Due to improved care, more and more children born with spina bifida in rural Kenya are surviving into adulthood. This improved survival has led to significant challenges in their lifestyles, especially the need to ensure pressure ulcer prevention and treatment. Malignant degeneration of pressure ulcers in spina bifida patients is very rare. The author describes the clinical presentation of two pressure ulcer carcinomas that are at variance from classical descriptions.

Materials and methods

An internet/Medline/PubMed search of English literature for theories on Marjolin's ulcer evolution and prognostic features of Marjolin's ulcers was performed.

A chart review of two young adults with spina bifida who had presented to the author's hospital between 2004 and August 2010 with chronic pressure ulcers found to be Marjolin's ulcers on histo-pathological examination was performed, and the clinical features are reported.

Results

The two ulcers appeared clinically benign: one was a deep ulcer, while the other was shallow; both had normal, benign-appearing edges, and a foul smelling discharge. The two ulcers were surrounded by induration and multiple communicating sinuses, with no evidence of chronic osteomyelitis. The internet search revealed a total of nine theories on Marjolin's ulcer development, as well as seven clinical and four histological prognostic features.

Discussion

The multifactorial theory, a coalescence of a number of proposed theories, best explains the evolution of Marjolin's ulcers. Poor prognostic features include pressure ulcer carcinomas, lesions and location in the lower limbs/trunks, all present in the two patients making their prognosis dim: this is despite the surgical margins being clear of tumor. Benign appearance, induration and presence of multiple communicating sinuses are features that have not been previously described as presenting features of pressure ulcers carcinomas.

Conclusion

There is need for spina bifida patients and their guardians/caretakers to receive a close follow-up throughout life; health education focused on pressure ulcer prevention as well as early treatment of pressure ulcers when they occur, will avert the development of Marjolin's ulcers, and save lives.

Malignant fibrous histiocytoma secondary to a traumatic hematoma

We present a case of malignant fibrous histiocytoma located in the region of the temple that corresponded to the main site of a traumatic hematoma. There are reports of malignant transformation triggered by different kinds of wounds, but the malignant transformation in a subcutaneous hematoma is rare. For chronic expanding hematoma, magnetic resonance imaging or biopsy is recommended in determining whether it is malignant, especially when the mass is growing rapidly.

CONDITIONAL NEOPLASMS AND SUBTHRESHOLD NEOPLASTIC STATES : A STUDY OF THE TAR TUMORS OF RABBITS

The "warts" which tar elicits on rabbit skin (papillomas, carcinomatoids, frill horns) are true tumors, benign growths expressive of slight yet irreversible deviations of epidermal cells from the normal. The neoplastic condition gives the cells a superiority over their neighbors when both are submitted to the same encouraging influences, and then they proliferate into tumors. Their state entails such disabilities, though, that they are unable to maintain themselves under ordinary circumstances, and consequently growths composed of them disappear when no longer aided. Often the neoplastic cells resume the normal aspect and habit of life long before the tumor mass is gone; and they may persist as part of an apparently normal epidermis, retaining their neoplastic potentialities for months after all signs of the growth have disappeared. In these instances it can be made to appear again, sometimes repeatedly, by non-carcinogenic stimulation of the skin (wound healing, turpentining). There is reason however to suppose that in the end the tumor cells, unless helped, die or are cast off. It is plain that the neoplastic state does not necessarily connote independence of behavior or success in tumor formation. On the contrary it may render cells unable to survive or endow them with powers which they can exert only under favoring conditions. This is the case with the cells composing the tar warts of rabbits. In the lack of such conditions the cells of these growths do not manifest themselves but remain in a subthreshold neoplastic state, whereas if aided they form neoplasms. The deviations from the normal represented by the benign tar tumors of rabbits are slight and limited in character, but further deviations in larger variety may be superimposed upon them, with result in malignant tumors, growths possessed of a greater, though not always absolute, independence. Tar cancers usually come about in this way, by successive, step-like deviations from the normal, and so also do the cancers which derive from virus-induced papillomas as well as many human carcinomas. After cells have become cancerous they frequently undergo further changes, some apparently step-like in character, and all taking the direction of greater malignancy. The hypotheses that tumors are due to somatic mutations and to viruses respectively are discussed in the light of these phenomena.

THE DETERMINING INFLUENCE OF TAR, BENZPYRENE, AND METHYLCHOLANTHRENE ON THE CHARACTER OF THE BENIGN TUMORS INDUCED THEREWITH IN RABBIT SKIN

The benign tumors of rabbit skin which appear in response to benzpyrene and methylcholanthrene are nearly all of the same kinds that tar produces, namely frill horns, papillomas, and carcinomatoids; but the collateral effects of these agents render many of them very different from the tar tumors. The connective tissue of the corium is so slowly excited by the pure hydrocarbons that for a long while it furnishes to most of the growths only a scanty stroma, when any, and in consequence they remain small,—low, dry, indolent, bas-relief affairs, made up almost entirely of the neoplastic epithelium,—not florid, fleshy excrescences with a large connective tissue component, such as tarring calls forth. The frill horns usually desquamate instead of building up like those due to tar, and some of their cells undergo a dyskeratotic change with result in spherical, homogeneous, deep-staining bullet-like elements, which give to the growths a singular aspect. In a frill horn due to benzpyrene numerous inclusion bodies were come upon which would seem to have been the result of intercurrent infection with a "passenger virus." Benzpyrene and methylcholanthrene produce papillomas, carcinomatoids, and frill horns in very different proportionate numbers from those obtaining when tar is the carcinogen. Tar gives rise much more frequently to carcinomatoids, —papillomas urged on to mimic cancers,—as would follow from its pronounced stimulating influence; yet it seldom produces frill horns whereas the pure hydrocarbons do so frequently. All three agents cause many more cells to become potentially capable of forming tumors than do so ordinarily, but the latent neoplastic elements on which tar exerts a promoting influence, causing them to form visible growths, are in general not the same as those which respond to benzpyrene and methylcholanthrene. Yet the relatively rare occurrence of frill horns due to tar cannot be wholly explained in this way and it becomes necessary to suppose that tar seldom changes normal cells into frill horn cells. Benzpyrene and methylcholanthrene give rise now and again to sebaceous adenomas, as tar does not. But tar does away with the sebaceous glands at an early period whereas the other two carcinogens cause them to increase notably in number. No evidence has been obtained that tar, benzpyrene, methylcholanthrene, arsenical preparations, or benzene,—which produces tumors of rabbit skin occasionally (1),—bring about any neoplastic changes peculiar to them individually when they act upon cells of a single sort, those of the stratum germinativum of rabbit epidermis. Yet the experimental findings make plain that these agents exert no inconsiderable influence on the morphology of the benign cutaneous growths they call forth and on the frequency with which this or that kind occurs. In appraising the action of carcinogens one must take into account not only the capacity of these agents to induce neoplastic change and to promote, or perhaps suppress, tumor growth but an ability to condition to no inconsiderable extent both the kind of tumor arising and its structure.

THE INITIATING AND PROMOTING ELEMENTS IN TUMOR PRODUCTION : AN ANALYSIS OF THE EFFECTS OF TAR, BENZPYRENE, AND METHYLCHOLANTHRENE ON RABBIT SKIN

Benzpyrene brings about neoplastic changes in rabbit epidermis much sooner than has been supposed. The long interval that elapses before visible growths appear is due in the main to the relatively slight power of the carcinogen to encourage multiplication of the cells it renders neoplastic. Yet some slight power of this sort it has. Methylcholanthrene has somewhat more but not nearly so much as tar. It may initiate neoplastic changes within less than 17 days, as compared with less than 10 days for tar, but tumors due to it do not ordinarily appear until months after those called forth by tarring. All three agents give rise to growths of essentially the same kinds, but most of those due to benzpyrene and methlycholanthrene remain for a long while small, dry, and indolent whereas many of the tar tumors are fleshy, vigorous, and rapidly enlarging,—differences wholly consequent on differences in the ability to promote growth. Such ability is an important element in the effectiveness of carcinogens. Tar and the polycyclic hydrocarbons cause many more cells to become tumor cells than give rise to visible growths. Benzpyrene is as effective in initiating neoplastic changes when dissolved in mineral oil as when in benzene, yet no tumors result from it until months after the benzene solution has given rise to them, the reason being that when in oil it is almost devoid of influence to encourage cell proliferation. Benzene itself has a very slight influence of the sort. Solvents may determine not only whether carcinogens initiate neoplastic change but may condition to a crucial degree the influence of these agents to encourage tumor formation. Rabbit epidermis is much more responsive to carcinogenic influences than that of the mouse, as measured in terms of time taken to elicit benign neoplasms. Even benzene will call forth these growths from rabbit skin. In appraising the relative responsiveness to carcinogens of various animal species it is essential to reckon in terms of cells of identical type.

Marjolin's ulcer of the scalp invading calvarial bone, dura and brain

A Marjolin's ulcer arising in a chronic scalp scar is reported. Malignant transformation occurred after four decades. The tumour had invaded the skull, dura mater and underlying brain tissue. This case illustrates the importance of appropriate and expeditious initial wound management of scar ulcers with high malignant potential to prevent this devastating outcome and also the role of reconstructive surgical techniques in radical surgery for scalp cancers.

Burn scar neoplasms: a literature review and statistical analysis

BACKGROUND

Although squamous cell carcinoma (SCC) is the most common burn scar neoplasm, other neoplasms have also been reported.

OBJECTIVE

To compile the burn scar neoplasm cases in the literature and to analyze their frequency and demographic characteristics.

MATERIALS AND METHODS

Cases were obtained through literature searches.

RESULTS

There were 412 cases gleaned from 146 articles between 1923 and 2004. Seventy-one percent (293) of the tumors were squamous cell carcinoma, 12% (48) were basal cell carcinoma (BCC), 6% (23) were melanoma, 5% (21) were sarcoma, 4% (16) were other neoplasms, 1% (6) were squamo-basal cell carcinoma, and 1% (5) squamous cell-melanoma. The mean age at tumor diagnosis was 50 years, the mean age at the time of burn injury was 20 years, the mean latency interval was 31 years. Only 5% of the reported cases were excised and grafted at the time of injury (p<0.001). BCC occurred at a significantly later age compared to SCC and sarcoma groups (p<0.02) and had a shorter latency period compared to SCC and sarcoma groups (p<0.004) and melanoma (p<0.008). Local recurrence was present in 16% of the cases, while regional lymph node involvement was seen in 22% of the cases and distant metastases was present in 14% of the patients. The mortality rate was 21%.

CONCLUSIONS

Although the main burn scar neoplasm was SCC, other neoplasms contributed to the morbidity and mortality of burn patients. Excision and grafting of deep burns, and close follow-up of non-healing ulcerated burn scars is essential for the prevention and early detection of burn scar neoplasms.

The pathogenesis of deferred cancer; a study of the after-effects of methylcholanthrene upon rabbit skin

The ears of young adult rabbits were painted with methylcholanthrene (MC) long enough to call forth a few benign tumors (papillomas, frill horns), and the animals were followed throughout their later lives. Soon after the paintings were stopped the tumors began to dwindle and vanished, yet even while they were disappearing other growths of the same kinds arose, only to vanish later in their turn. For a long while more arose than disappeared, and in consequence the number of tumors increased throughout years. They accumulated at a constant rate despite concurrent changes in the supporting skin, which might have been supposed, on previous experience, to have prevented this from happening. Only in the old age of the animals did the number of tumors eventually fall off, and by this time the skin on which they had arisen, long since normal in the gross to all appearance, had become nearly so microscopically. Even then latent neoplastic potentialities still existed in the cutaneous tissue; where punch holes were healing new tumors arose. A great multitude of hidden neoplastic cells were present in the MCed skin, and from them many of the growths called forth by the stimulus of healing undoubtedly derived. Yet the facts make it difficult to suppose that the long accumulation, at a constant rate, of tumors visible in the gross was due wholly to the proliferation of cells rendered neoplastic during the period of exposure to MC, and lying hidden afterwards for periods determined by their differing, evenly graded capabilities. Nor can the accumulation be attributed to a sustained carcinogenesis resulting from the pathological state of the skin. As a whole the findings indicate that the linear increase in growths was due for the most part to a continual arrival at the neoplastic state and subsequent proliferation of cells, or the descendants of cells, that had been no more than started on the way toward becoming neoplastic by the carcinogen. There is clinical evidence for such a course of events. Now and again a carcinoma arose from the skin previously treated with MC, but they were few in all, as would follow from the presence of local conditions unfavorable to malignant change. Some appeared only after years,—in one instance more than 5 years after. The occurrence of deferred cancer in man can be understood in terms of the findings in rabbits.

Age of the host and other factors affecting the production with urethane of pulmonary adenomas in mice

Young, rapidly growing mice are greatly more responsive to the adenoma-inducing influence of urethane than are those just arriving at maturity. This is manifest both in the proportion of animals developing the tumors and in their number per individual. An amount of urethane per gram body weight which suffices to induce adenomas in only an occasional 8-week-old animal will cause them to appear in quantity in more than half the 3-week-old mice injected. There is an almost absolute inverse correlation between the rate of growth of the pulmonary tissue between the ages of 2 and 10 weeks and the response to urethane in terms of adenomas. Hence the conclusion seems justified that the natural proliferative activity of the alveolar cells during youth plays a major part in the formation of the tumors. After the 6th week the age differences become relatively slight, yet there is reason to think that they continue in some degree as life goes on. Urethane has no effect to promote multiplication of the cells it has rendered neoplastic, its whole role being to initiate neoplastic change. The abnormalities induced by urethane in the nucleus of normal and neoplastic cells, as observed by previous workers, have suggested that the substance brings about the adenomatous state by acting upon the nucleus. But colchicine, also a karyolytic poison causing pronounced nuclear changes, does not alter in the least the yield of adenomas to urethane when administered concurrently. Nor does fasting influence the yield, though it markedly reduces mitotic activity. The meaning of these facts is discussed.

Histogenesis of sebaceous gland carcinomas produced in rats by 2-acetylaminofluorene

1. Tumors of the external auditory canal region were produced by oral administration of 2-acetylaminofluorene in 71 rats out of 124 which survived a 6 month period of administration of the compound. In 12 animals the tumors were bilateral. Tumors in other locations, such as the liver, breast, etc., were less frequent. 2. Tumors were found to originate in the compound sebaceous gland located at the medial end of the external auditory canal. 3. Histologically the tumors were sebaceous or keratinizing squamous-cell carcinomas. 4. The tumors were found to arise in cystic lobules of the gland, produced by stasis of secretion. 5. Cystic lesions of the sebaceous glands appear to be a frequent condition in older rats. The outward bulging of the tympanic membrane with interference in drainage from the gland seems to be a promoting factor in the stasis of sebum. 6. The localizing effect of the preexisting cystic lesions in the sebaceous glands on the carcinogenic action of 2-acetylaminofluorene is discussed.

Joint action of a chemical carcinogen and a neoplastic virus to induce cancer in rabbits; results of exposing epidermal cells to a carcinogenic hydrocarbon at time of infection with the Shope papilloma virus

Areas of rabbit skin previously rendered hyperplastic with turpentine were scarified, inoculated with the Shope papilloma virus, and covered with a dressing that contained 20-methylcholanthrene (MC) or 9:10-dimethyl-1:2-benzanthracene (9:10). The dressing was left on until healing had been well completed, a matter of 5 to 7 days. The papillomas which subsequently arose often appeared later, were fewer, and remained less vigorous than those due to the action of virus alone, but throughout several months they appeared to differ from these in no other ways. Then, more or less abruptly, the large majority became carcinomatous, frequently at several situations, whereas with few exceptions the control growths underwent no such alteration. The cancers were of the sorts ordinarily deriving, by secondary change, from epidermal cells infected with the virus. Collateral data have made plain that the hydrocarbons acted in their carcinogenic capacity to bring on the cancers. Indeed in control tests 9: 10 sometimes conferred latent neoplastic potentialities on uninoculated epidermis exposed to it while healing after scarification, a fact disclosed months later by painting these expanses with chloroform until hyperplasia occurred. Under the promoting influence of this agent papillomas formed which had the distinctive morphology of those induced by the chemical carcinogens. So strong and enduring were the effects of MC and 9:10 as to cause cancers to arise from many virus papillomas which were retrogressing after months of proliferation, that is to say under circumstances ordinarily unfavorable to malignant change. The facts justify the conclusion that the virus and the hydrocarbons acted jointly and in their carcinogenic capacities.

Potential of p38 MAP kinase inhibitors in the treatment of cancer

The involvement of chronic inflammation in tumor development and progression is reviewed. Based on the natural history of certain diseases and epidemiology studies, a strong association has been established between particular chronic inflammatory conditions and eventual tumor appearance. Solid tumors require a stroma for their growth and recruit macrophages to synthesize essential growth and angiogenic factors that they do not have the capacity to produce. The microenvironment of the local host tissue appears to be an active participant in exchanging cytokines and enzymes with tumor cells that modify the local extracellular matrix, stimulate migration, and promote tumor angiogenesis, proliferation and survival. The role of p38 MAP kinase as a therapeutic target for treating cancer is discussed.

Inflammation and cancer

Recent data have expanded the concept that inflammation is a critical component of tumour progression. Many cancers arise from sites of infection, chronic irritation and inflammation. It is now becoming clear that the tumour microenvironment, which is largely orchestrated by inflammatory cells, is an indispensable participant in the neoplastic process, fostering proliferation, survival and migration. In addition, tumour cells have co-opted some of the signalling molecules of the innate immune system, such as selectins, chemokines and their receptors for invasion, migration and metastasis. These insights are fostering new anti-inflammatory therapeutic approaches to cancer development.

Inflammation and cancer

Recent data have expanded the concept that inflammation is a critical component of tumour progression. Many cancers arise from sites of infection, chronic irritation and inflammation. It is now becoming clear that the tumour microenvironment, which is largely orchestrated by inflammatory cells, is an indispensable participant in the neoplastic process, fostering proliferation, survival and migration. In addition, tumour cells have co-opted some of the signalling molecules of the innate immune system, such as selectins, chemokines and their receptors for invasion, migration and metastasis. These insights are fostering new anti-inflammatory therapeutic approaches to cancer development.

Chemical carcinogens as foreign bodies and some pitfalls regarding cancer immune surveillance

Interferon-gamma-receptor (IFN-gammaR)-deficient mice are more susceptible to tumor induction by methylcholanthrene (MCA) in comparison to control littermates. The cellular source of IFNgamma is not known, but the absence of T cells does not significantly increase the incidence of MCA-induced tumors. However, it appears that the presence of T cells in combination with unknown, perhaps environmental, factors can decrease MCA-induced tumor incidence, indicating that IFN-gamma of unknown origin contributes to the protective response. The current knowledge of cancer biology, immune regulation, and tumor-promoting effects of inflammation are difficult to reconcile with the concept of immune surveillance against non-virus-associated cancer. Analysis of the primary MCA-treated mouse indicates, as one protective mechanism, a tissue repair response against MCA-induced damage, in the course of which MCA is encapsulated and persists for long time in tumor-free mice, termed foreign-body reaction. The protection from DNA damage could simultaneously diminish tissue injury and malignant transformation. We argue that inhibition of MCA-induced carcinogenesis is mechanistically different from tumor transplantation immunity and that a longer latency in MCA-treated mice is unlikely due to T cell-mediated tumor recognition and selection of less immunogenic variants. We discuss that the IFNgammaR-dependent mechanism against MCA is unrelated to the original concept of T cell-mediated immune surveillance and that the increased spontaneous tumor incidence observed in some immune-deficient mice is likely to be explained by opportunistic infection and tumor-promoting chronic inflammation.

Microenvironmental Regulation of the Initiated Cell

In the classical skin model of tumor initiation, keratinocytes treated once with carcinogen retain their normal appearance and growth behavior indefinitely unless promoted to growth into papillomas. Because many of the papillomas regress and may recur with further promotion, their cells can also be considered as initiated. The growth of initiated keratinocytes can be inhibited either in vitro or in vivo by close association with an excess of normal keratinocytes, but it is enhanced by dermal fibroblasts. Chick embryo fibroblasts (CEF) in culture produce transformed foci after infection with Rous sarcoma virus (RSV) on a background of normal CEF in a medium containing 10% or less calf serum (CS), but they retain normal appearance and growth regulation in 10% fetal bovine serum (FBS) or 20% CS. Transformation of a carcinogen-treated line of mouse embryo fibroblasts is prevented, and can be reversed, in high concentrations of FBS in the presence of an excess of normal cells. FBS has high, broad-spectrum antiprotease activity. Increased protease production occurs in a variety of transformed cells and is correlated with progression in tumors. Protease treatment stimulates DNA synthesis and mitosis in confluent, contact-inhibited normal cell cultures. Synthetic inhibitors of proteases suppress transformation in carcinogen-treated cultures and inhibit tumor formation in animals. Several different classes of protease may be overexpressed in the same transformed cells. It is proposed that excessive protease production accounts for major features of neoplastic transformation of initiated cells, but that transformation can be held in check by protease inhibitors present in serum and released from surrounding cells. It would be informative to determine whether high concentrations of FBS would inhibit the neoplastic development of initiated keratinocytes.

Inflammation and cancer

Recent data have expanded the concept that inflammation is a critical component of tumour progression. Many cancers arise from sites of infection, chronic irritation and inflammation. It is now becoming clear that the tumour microenvironment, which is largely orchestrated by inflammatory cells, is an indispensable participant in the neoplastic process, fostering proliferation, survival and migration. In addition, tumour cells have co-opted some of the signalling molecules of the innate immune system, such as selectins, chemokines and their receptors for invasion, migration and metastasis. These insights are fostering new anti-inflammatory therapeutic approaches to cancer development.

Selective clonal expansion and microenvironmental permissiveness in tobacco carcinogenesis

Historically our knowledge about the direct carcinogenic activity of cigarette smoke and its constituents grew from painting experiments on the skin of mice to produce papillomas and carcinomas. The neutral fraction of cigarette smoke condensate had most of the carcinogenic activity in this test and was rich in carcinogenic polycyclic aromatic hydrocarbons (PAHs), the most abundant by far being BP. However, the concentration of BP in the condensate was only about 2% the amount of pure BP required to cause skin tumors. In other fractions there were non-carcinogenic constituents that promoted tumor formation when applied repeatedly to mouse skin that had been initiated by a single subcarcinogenic application of BP. There were also constituents of cigarette smoke that acted as co-carcinogens when applied simultaneously with repeated applications of BP. BP was effective as an initiator at lower concentrations than as a complete carcinogen, and some non-carcinogenic PAHs in the condensate were also active initiators. It was concluded from these studies that cigarette smoke condensate is primarily a tumor-promoting and co-carcinogenic agent with weak activity as a complete carcinogen. A major effect of promoters, and possibly of co-carcinogens, is a diffuse hyperplasia which includes selective expansion of clones carrying endogenous mutations and/or mutations induced by PAHs and other carcinogens such as NNK. The induced mutations as well as damaged cells would occur throughout the exposed region and, along with the hyperplasia, increase the permissiveness of the cellular microenvironment for neoplastic expression of any potential tumor cell in its midst. Since neither the promoters nor co-carcinogens in tobacco smoke are known to interact directly with DNA, their effects can be considered epigenetic processes that act upon genetically altered cells. Examples are cited from studies of experimental skin carcinogenesis, smoking-induced histopathological changes in human lung and spontaneous transformation in cell culture to illustrate the genetic and epigenetic interactions of neoplastic development in general and their significance for smoking-induced lung cancer in particular. Certain dietary modifications that appear to be effective in moderating the promotional phase of animal and human carcinogenesis are suggested for trial in managing lung cancer.

Inhibition of methylcholanthrene-induced carcinogenesis by an interferon gamma receptor-dependent foreign body reaction

The foreign body reaction is one of the oldest host defense mechanisms against tissue damage which involves inflammation, scarring, and encapsulation. The chemical carcinogen methylcholanthrene (MCA) induces fibrosarcoma and tissue damage in parallel at the injection site. Tumor development induced by MCA but not due to p53-deficiency is increased in interferon-gamma receptor (IFN-gammaR)-deficient mice. In the absence of IFN-gammaR, MCA diffusion and DNA damage of surrounding cells is increased. Locally produced IFN-gamma induces the formation of a fibrotic capsule. Encapsulated MCA can persist virtually life-long in mice without inducing tumors. Together, the foreign body reaction against MCA prevents malignant transformation, probably by reducing DNA damage. This mechanism is more efficient in the presence of IFN-gammaR. Our results indicates that inflammation and scarring, both suspected to contribute to malignancy, prevent cancer in certain situations.

Synergistic mechanisms in carcinogenesis by polycyclic aromatic hydrocarbons and by tobacco smoke: a bio-historical perspective with updates

B[a]P (benzo[a]pyrene) has been used as a prototype carcinogenic PAH since its isolation from coal tar in the 1930's. One of its diol epoxides, BPDE-2, is considered its ultimate carcinogen on the basis of its binding to DNA, mutagenicity and extreme pulmonary carcinogenicity in newborn mice. However, BPDE-1 has a similar binding to DNA and mutagenicity but it is not carcinogenic. In addition, BPDE-2 is a weak carcinogen relative to B[a]P when repeatedly applied to mouse skin, the conventional assay site. Its carcinogenicity is increased when applied once as an initiator followed repeatedly by a promoter. This indicates a major role for promotion in carcinogenesis by PAHs. Promotion itself is a 2-stage process, the second of which is selective propagation of the initiated cells. Persistent hyperplasia underlies selection by promoters. The non-carcinogenicity of BPDE-1 has yet to be resolved. PAHs have long been considered the main carcinogens of cigarette smoke but their concentration in the condensate is far too low to account by themselves for the production of skin tumors. The phenolic fraction does however have strong promotional activity when repeatedly applied to initiated mouse skin. Several constituents of cigarette smoke are co-carcinogenic when applied simultaneously with repeated applications of PAHs. Catechol is co-carcinogenic at concentrations found in the condensate. Since cigarette smoking involves protracted exposure to all the smoke constituents, co-carcinogenesis simulates its effects. Both procedures, however, indicate a major role for selection in carcinogenesis by cigarette smoke. That selection may operate on endogenous mutations as well as those induced by PAHs. There are indications that the nicotine-derived NNK which is a specific pulmonary carcinogen in animals contributes to smoking-induced lung cancer in man. Lung adenoma development by inhalation has been induced in mice by the gas phase of cigarette smoke. The role of selection has not been evaluated in either of these cases.

Malignant melanoma arising within a burn scar case report and review of the literature

Burn scar carcinomas, also called Marjolin's ulcers, are uncommon tumors that arise from an antecedent burn. Most burn scar carcinomas are diagnosed about 30 years after the burn, and most are well-differentiated squamous cell carcinomas. We report a case in which a squamous cell carcinoma developed within a burn scar on the cheek and then a malignant melanoma arose within the burn scar after the squamous cell carcinoma had been excised. We also review the available literature on burn scar carcinoma, covering the demographics, pathogenesis, diagnosis, prognosis, and treatment of the disease. Given the multifocality of this disease process, we advocate aggressive resection of the entire burn scar, as well as the tumor, to prevent the development of further cancers within the wound.

Marjolin's ulcer of the scalp: report of 5 cases and review of the literature

The formation of neoplastic changes in the scar tissue of chronically ulcerating wounds is a well-known process. This condition is most commonly seen after the postburn scars, but it may be seen after many kinds of scars. The term "Marjolin's ulcer" is used to describe this type of carcinoma. Although many different cell types can be seen in these lesions, the most commonly seen is squamous cell carcinoma. Squamous cell carcinomas resulting from the Marjolin's ulcer have a much greater tendency to metastasize than squamous cell carcinomas resulting from the other causes. Confusion continues about the precise pathophysiology of this lesion and the clinical behavior of this neoplasm, and the mortality and morbidity rates are also conflicting. As would be expected, there is a wide variety of suggested treatment protocols for this disease. This article, through case reports and review of the literature, offers criteria for the treatment of the Marjolin's ulcers that arise on the scalp, which is an uncommon site.

Enhanced growth of primary tumors in cancer-prone mice after immunization against the mutant region of an inherited oncoprotein

One major objective of tumor immunologists is to prevent cancer development in individuals at high risk. (TG.AC x C57BL/6)F1 mice serve as a model for testing the feasibility of this objective. The mice carry in the germline a mutant ras oncogene that has an arginine at codon 12 instead of glycine present in the wild-type, and after physical (wounding) or chemical promotion, these mice have a high probability for developing papillomas that progress to cancer. Furthermore, F1 mice immunized with Arg(12) mutant ras peptide in complete Freund's adjuvant (CFA) develop T cells within 10 d that proliferate in vitro on stimulation with the Arg(12) mutant ras peptide. Within 14 d, these mice have delayed-type hypersensitivity to the peptide. Immunization with CFA alone or with a different Arg(12) mutant ras peptide in CFA induced neither response. To determine the effect of immunization on development of tumors, mice immunized 3 wk earlier were painted on the back with phorbol 12-myristate 13-acetate every 3 d for 8 wk. The time of appearance and the number of papillomas were about the same in immunized and control mice, but the tumors grew faster and became much larger in the mice immunized with the Arg(12) mutant ras peptide. Thus, the immunization failed to protect against growth of papillomas. The peptide-induced CD4(+) T cells preferentially recognized the peptide but not the native mutant ras protein. On the other hand, mice immunized with Arg(12) mutant ras peptide and bearing papillomas had serum antibodies that did bind native mutant ras protein. Together, these studies indicate that active immunization of cancer-prone individuals may result in immune responses that fail to eradicate mutant oncogene-expressing tumor cells, but rather induce a remarkable enhancement of tumor growth.

The development of a Marjolin's cancer in a human immunodeficiency virus-positive hemophilic man and review of the literature

BACKGROUND

The malignant potential of chronic ulcers and scars secondary to a variety of injuries is well characterized in the medical literature. Furthermore, it has been reported that human immunodeficiency virus (HIV)-positive patients have a higher incidence of basal cell carcinoma (BCC) than the general population.

OBJECTIVE

To describe a case of an unusually aggressive morpheaform BCC that developed in a 28-year-old HIV-positive patient. The tumor developed in a scar 25 years after the initial trauma (Marjolin's ulcer).

METHODS

Description of a case and review of the literature of Marjolins ulcer.

RESULTS

The tumor was removed in a seven-stage, 21-section, micrographically controlled excision. Intraoperatively, perineural invasion of the infraorbital nerve was observed. The postoperative defect was repaired using a full-thickness skin graft.

CONCLUSION

Although most malignancies arising within chronic scars are SCCs, BCCs and a number of other tumors have been described. Mohs micrographic surgery was effective in treating this aggressive morpheaform BCC. A high degree of suspicion in any changing healed scar is recommended.

The many faces of squamous cell carcinoma

BACKGROUND

Cutaneous squamous cell carcinoma is a disease that has a multitude of clinical, histologic, and etiologic subtypes, all of which are of significance to the clinician.

OBJECTIVE

Ten of the most common and clinically significant subtypes of squamous cell carcinoma are presented to emphasize the clinical importance of each and to emphasize and contrast their differences.

METHODS

The literature of each subtype of squamous cell carcinoma is reviewed and capsulized.

RESULTS

Appropriate diagnosis, therapy, and postoperative management of all subtypes of squamous cell carcinomas are dependent upon the understanding of their unique characteristics.

CONCLUSION

The 10 common variants of squamous cell carcinoma presented in this paper: neurotrophic squamous cell carcinoma, Bowen's disease, squamous cell carcinoma in transplant patients, keratoacanthoma-like squamous cell carcinoma, squamous cell carcinoma of the lip, adenoid squamous cell carcinoma, spindle cell squamous cell carcinoma, radiation-induced squamous cell carcinoma, verrucous carcinoma, and Marjolin's ulcer, have unique etiologic, histologic, and clinical features that significantly influence their diagnosis, treatment, and subsequent management. It is imperative that physicians responsible for the care of these patients understand the implication of these unique characteristics.

Promotion as a factor in carcinogenesis

Promotion is any factor which results in the increased cellular replication of initiated or transformed cells. We argue that cytotoxicity is not a necessary component of promotion and that, therefore, the existence of a threshold for promotion is unlikely.