Enhanced experimental metastatic capacity of a murine melanoma following pre-treatment with anticancer drugs

Epigenetic Regulation in Melanoma: Facts and Hopes

Cutaneous melanoma is a lethal disease, even when diagnosed in advanced stages. Although recent progress in biology and treatment has dramatically improved survival rates, new therapeutic approaches are still needed. Deregulation of epigenetics, which mainly controls DNA methylation status and chromatin remodeling, is implied not only in cancer initiation and progression, but also in resistance to antitumor drugs. Epigenetics in melanoma has been studied recently in both melanoma preclinical models and patient samples, highlighting its potential role in different phases of melanomagenesis, as well as in resistance to approved drugs such as immune checkpoint inhibitors and MAPK inhibitors. This review summarizes what is currently known about epigenetics in melanoma and dwells on the recognized and potential new targets for testing epigenetic drugs, alone or together with other agents, in advanced melanoma patients.

Delay to surgery after neoadjuvant chemotherapy in head and neck squamous cell carcinoma affects oncologic outcomes

BACKGROUND

Neoadjuvant chemotherapy (NAC) is used in head and neck squamous cell carcinoma (HNSCC) for downstaging advanced disease and decreasing distant metastasis (DM). To the authors' knowledge, no study has specifically examined the impact of a delayed time to surgery (TTS) after NAC on oncologic outcomes. They thus aimed to identify a cutoff for TTS after NAC and its effect on survival indices.

METHODS

This was a retrospective review of all patients with HNSCC receiving NAC followed by surgery with curative intent between March 2016 and March 2019 at the MD Anderson Cancer Center. Receiver operating characteristic analysis was used to identify a cutoff for TTS, and this cutoff was used to analyze the overall survival (OS), locoregional recurrence rate, DM-free rate, and disease-free survival (DFS). A multivariate Cox regression analysis was performed.

RESULTS

One hundred one patients were analyzed with a median follow-up of 24.7 months. The 3-year OS and locoregional recurrence rates did not differ with a TTS ≥ 34 days. However, the 3-year DM-free rate was significantly worse (56% vs 90%; P = .001) in the group with a TTS ≥ 34 days, and the 3-year DFS was significantly lower (26% vs 64%; P = .006). In a multivariate analysis, a TTS ≥ 34 days (hazard ratio [HR], 4.92; 95% confidence interval [CI], 1.84-13.13) and extracapsular extension (HR, 3.01; 95% CI, 1.13-8.00) were significant independent predictors of a poorer DM-free rate. Weight loss > 10% (HR, 5.53; 95% CI, 1.02-30.24) was the only independent predictor for a TTS ≥ 34 days.

CONCLUSIONS

Emphasis should be placed on early definitive locoregional treatment after NAC, particularly in patients who do not respond to NAC. There is a need to validate these findings and establish new benchmarks for the interval between NAC and surgery.

The efficacy of induction chemotherapy in the treatment of stage II nasopharyngeal carcinoma in intensity modulated radiotherapy era

PURPOSE

To evaluate the efficacy of induction chemotherapy in the treatment of stage II nasopharyngeal carcinoma (NPC) in era of intensity modulated radiotherapy (IMRT).

METHODS AND MATERIALS

A total of 173 patients with American Joint Committee on Cancer (AJCC) 7th stage II NPC from two institutions were included. All patients were divided into two groups: induction chemotherapy + concurrent chemoradiotherapy group (ICRT) group and concurrent chemoradiotherapy group (CCRT). Induction chemotherapy was consisted of one to three cycles of cisplatin plus fluorouracil (PF) or paclitaxel plus cisplatin (TP). Concurrent chemotherapy included one to three cycles of cisplatin. We retrospectively assessed overall survival (OS), progression-free survival (PFS), locoregional failure free survival (LRFFS) and distant metastasis free survival (DMFS) in patients of both groups. T-test, Chi-square test, Kaplan-Meier methodology and Cox proportional hazards model were used to analyze.

RESULTS

With a median follow up of 64.7 months, no significant difference was found in grade 3-4 hematologic toxicity, liver dysfunction and renal impairment between ICRT and CCRT group. Univariable analyses shown adding induction chemotherapy to CCRT significantly decreased 5-year OS (87.9% vs 95.5%, P = 0.033), 5-year PFS (74.0% vs 86.1%, P = 0.035), 5-year LRFFS (80.0% vs 91.2%, P = 0.016), but there was no statistically significant difference in 5-year DMFS (87.1% vs 94.7%, P = 0.095). In multivariable analyses, we found the consistent results that induction chemotherapy was a negative factor associated with OS (HR of death = 3.768, 95% CI = 1.117-12.709; P = 0.032), PFS (HR of progression = 2.156, 95% CI = 1.060-4.386; P = 0.034), LRFFS (HR of locoregional relapse = 2.435, 95% CI = 1.009-5.874; P = 0.048) and also DMFS (HR of metastasis = 2.873, 95% CI = 1.005-8.211; P = 0.049), in stage II NPC patients.

CONCLUSION

In present study, we found that induction chemotherapy caused deleterious effect on stage II NPC patients. However, this is a retrospective study and the adverse effects of induction chemotherapy has not been previously reported. It warrants further investigation.

Prodding the Beast: Assessing the Impact of Treatment-Induced Metastasis

The arsenal of treatments for most cancers fit broadly into the categories of surgery, chemotherapy, radiation, and targeted therapy. All represent proven and successful strategies, yet each can trigger local (tumor) and systemic (host) processes that elicit unwanted, often opposing, influences on cancer growth. Under certain conditions, nearly all cancer treatments can facilitate metastatic spread, often in parallel (and sometimes in clear contrast) with tumor reducing benefits. The paradox of treatment-induced metastasis (TIM) is not new. Supporting preclinical studies span decades, but are often overlooked. With recent evidence of prometastatic effects following treatment with targeted agents blocking the tumor microenvironment, a closer inspection of this literature is warranted. The TIM phenomena may diminish the impact of effective therapies and play a critical role in eventual resistance. Alternatively, it may simply exemplify the gap between animal and human studies, and therefore have little impact for patient disease and treatment. This review will focus on the preclinical model systems used to evaluate TIM and explore the mechanisms that influence overall treatment efficacy. Understanding the role of TIM in established and emerging drug treatment strategies may help provide rationales for future drug combination approaches with antimetastatic agents to improve outcomes and reduce resistance.

Melanoma epigenetics: novel mechanisms, markers, and medicines

The incidence and mortality rates of cutaneous melanoma continue to increase worldwide, despite the deployment of targeted therapies. Recently, there has been rapid growth and development in our understanding of epigenetic mechanisms and their role in cancer pathobiology. Epigenetics--defined as the processes resulting in heritable changes in gene expression beyond those caused by alterations in the DNA sequence--likely contain the information that encodes for such phenotypic variation between individuals with identical genotypes. By altering the structure of chromatin through covalent modification of DNA bases or histone proteins, or by regulating mRNA translation through non-coding RNAs, the epigenome ultimately determines which genes are expressed and which are kept silent. While our understanding of epigenetic mechanisms is growing at a rapid pace, the field of melanoma epigenomics still remains in its infancy. In this Pathology in Focus, we will briefly review the basics of epigenetics to contextualize and critically examine the existing literature using melanoma as a cancer paradigm. Our understanding of how dysregulated DNA methylation and DNA demethylation/hydroxymethylation, histone modification, and non-coding RNAs affect cancer pathogenesis and melanoma virulence, in particular, provides us with an ever-expanding repertoire of potential diagnostic biomarkers, therapeutic targets, and novel pathogenic mechanisms. The evidence reviewed herein indicates the critical role of epigenetic mechanisms in melanoma pathobiology and provides evidence for future targets in the development of next-generation biomarkers and therapeutics.

Critical Review of Preclinical Approaches to Evaluate the Potential of Immunosuppressive Drugs to Influence Human Neoplasia

Many immunosuppressive drugs are associated with an increased risk of B-cell lymphoma, squamous cell carcinoma, and Kaposi sarcoma. Thirteen immunosuppressive drugs have been tested in 2-year carcinogenicity studies (abatacept; azathioprine; busulfan; cyclophosphamide; cyclosporine; dexamethasone; everolimus; leflunomide; methotrexate; mycophenolate mofetil; prednisone; sirolimus; and tacrolimus) and in additional models including neonatal and genetically modified mice; chemical, viral, ultraviolet, and ionizing radiation co-carcinogenesis, and in models with transplanted tumor cells. The purpose of this review is to outline the mechanisms by which immunosuppressive drugs can influence neoplasia, to summarize the available preclinical data on the 13 drugs, and to critically review the performance of the models. A combination of primary tumor and metastasis assays conducted with transplanted cells may provide the highest value for hazard identification and can be applied on a case-by-case basis. However, for both small molecules and therapeutic proteins, determining the relative risk to patients from preclinical data remains problematic. Classifying immunosuppressive drugs based on their mechanism of action and hazard identification from preclinical studies and a prospective pharmacovigilance program to monitor carcinogenic risk may be a feasible way to manage patient safety during the clinical development program and postmarketing.

Development of resistance to vincristine and doxorubicin in neuroblastoma alters malignant properties and induces additional karyotype changes: a preclinical model

Cytotoxic drug treatment of neuroblastoma often leads to the development of drug resistance and may be associated with increased malignancy. To study the effects of long-term cytotoxic treatment on malignant properties of tumor cells, we established 2 neuroblastoma cell sublines resistant to vincristine (VCR) and doxorubicin (DOX). Both established cell lines (UKF-NB-2(r)VCR(20) and UKF-NB-2(r)DOX(100)) were highly resistant to VCR, DOX and vice-versa but retained their sensitivity to cisplatin. UKF-NB-2(r)VCR(20) and UKF-NB-2(r)DOX(100) expressed significant amounts of P-glycoprotein, while parental cells were P-glycoprotein negative. GD2 expression was upregulated, whereas NCAM expression was decreased in both resistant cells. Spectral karyotype (SKY) analysis revealed complex aberrant karyotypes in all cell lines and additional acquired karyotype changes in both resistant cells. All cell lines harbored high levels of N-myc amplification. Compared to parental cells, UKF-NB-2(r)VCR(20) and UKF-NB-2(r)DOX(100) exhibited more than 2-fold increase in clonal growth in vitro, accelerated adhesion and transendothelial penetration and higher tumorigenicity in vivo. We conclude that development of drug resistance and acquisition of certain karyotypic alterations is associated with an increase of additional malignant properties that may contribute to the poor prognosis in advanced forms of NB. The 2 novel neuroblastoma cell sublines also provide useful models for the study of drug resistance in aggressive forms of neuroblastoma.

Induction of heat shock protein 27 by hydroxyurea and its relationship to experimental metastasis

Treatment of tumor cells with hydroxyurea (HU) has been shown to increase the experimental metastatic potential of these cells. We have previously described the induction of stress proteins (antioxidants) by HU in B16 murine melanoma cells and their relationship to the metastatic process. We have now investigated the induction by HU of another set of stress proteins, the heat shock proteins, and their role in experimental metastasis. HU markedly increased the cellular content of heat shock protein (hsp) 27 but not of hsp 90, 72/73, or 60 as measured by immunoblotting. The induction of hsp27 protein was preceded by a specific increase in hsp27 mRNA. Furthermore, HU-treated cells were more thermotolerant. To investigate the functional role of hsp27, human hsp27 cDNA was constitutively overexpressed in B16 cells at levels seen in HU-treated cells. In separate experiments, we induced a global increase in hsps by heat shock. Neither the hsp27 transfectants nor the heat-shocked cells demonstrated an increase in their experimental metastatic capacity. We conclude that hsp27 protein is increased by HU by the specific induction of hsp27 mRNA in B16 melanoma cells but increased hsp27 protein is not responsible for the increase in experimental metastasis. Since high levels of hsp27 are associated with metastatic disease in breast and ovarian cancers, but not in our experimental system, the functional role of hsp27 in metastasis requires further study.

Antimetabolite-induced increases in the invasive capacity of murine leukaemia L1210 cells

Pretreatment of murine leukaemia L1210 cells with non-lethal concentrations of various antimetabolites increased the in vitro invasive capacity of these cells into monolayers of rat embryo fibroblasts. The increase in invasive capacity was partly correlated with the induced cell cycle arrest. The concomitant increase in cell surface fucosylation and inhibition of invasion with sulphate indicate a role for glycoproteins in this process. Our results suggest that treatment with antimetabolites may lead to a more aggressive phenotype by altering cell surface properties.

Isolation and characterization of a low metastatic variant from EL-4 mouse T-lymphoma

A variant cell line (EL-4ad) which adhered to a tissue culture dish was isolated from highly metastatic EL-4 murine T-lymphoma. The experimental and spontaneous metastatic ability of EL-4ad was lower than that of the EL-4 parent cell line. The cell surface phenotypes of both cell lines were CD2+3+4-8-45+TCR alpha beta+TCR gamma delta-, but the level of CD2 expression of EL-4ad was much lower than that of EL-4. Furthermore, EL-4ad had higher binding ability to fibronectin and expressed more PNA receptors on the cell surface than EL-4. These differences indicated that either the maturation stage of the less metastatic variant was lower than that of the parent cell line or the activation state of the two cell lines differed. EL-4ad showed higher in vitro invasiveness and adhesiveness to liver cells, and these characters were not consistent with the reduced metastatic ability of this variant. Neuraminidase-releasable cell surface sialic acid levels did not differ significantly between the cell lines. Neither cell line was adhesive to laminin, type IV collagen or reconstituted basement membrane. These metastasis-related properties could not explain the decreased metastatic ability of EL-4ad. On the other hand, EL-4ad was more sensitive to NK activity than EL-4 in vivo, and this was thought to be a major cause of its decreased metastatic ability. The molecules or mechanisms involved in the differentiation or activation of T-cells may be responsible for the sensitivity of tumor cells to NK activity.

Radiation enhancement of metastasis: a review

Virtually every modality employed in the treatment of cancer has demonstrated an adverse effect upon metastasis under some conditions. This review surveys the experimental and clinical literature pertaining to the untoward effects of ionizing radiation upon metastatic processes. Two processes are described: (1) enhancement of metastases following local tumor irradiation; (2) localization of metastasis in previously irradiated normal tissues. In the first process the experimental evidence indicates a local effect of irradiation upon the tumor-stroma interface. It predominates under conditions of non-curative radiation doses. There is no proof that this process occurs in clinical practice, but a review of data provides suggestive evidence for its existence following non-curative therapy. The second process is documented both experimentally and clinically. It requires the presence of viable, circulating tumor cells and appears mediated through vascular damage. The few clinical reports suggest that this effect is rare in practice. The clinical significance of both processes appears small under conditions of effective tumor therapy, but it is speculated that inadequate tumor irradiation, or irradiation of normal tissues with uncontrolled tumor elsewhere, may be deleterious.

Tumor progression: potential role of unstable genomic changes

It is generally accepted that the genome of tumor cells is less stable than that of most normal cells, and it has been hypothesized that this genomic instability is probably involved in the process of tumor progression. However, the rate of occurrence of classical spontaneous mutations in tumor cells is too low to account for the rapid changes that can occur during tumor progression. Thus it is likely that other types of changes, such as gene amplification, must be involved in tumor progression. Gene amplification has been extensively studied in relation to the development of drug resistance. Low levels of amplification can occur spontaneously in tumor cell populations, but the amplified genes are lost rapidly unless prolonged selective pressure is applied. This paper argues that unstable increases in the expression of genes, probably as a result of low levels of amplification, may be all that is required for some of the stages in the process of tumor progression. This may be particularly true for the steps involved in metastasis formation. Recent studies have suggested that microenvironmental conditions known to occur in tumors (hypoxia, nutrient deprivation) may induce gene amplification in cells. This suggests the possibility that such conditions could promote tumor progression.

Combined modality treatment with radiotherapy and chemotherapy

Combined modality treatment with radiotherapy and chemotherapy is used increasingly for the primary management of a variety of human tumours, with the aim of improving both local and distant control. The present paper reviews methodological issues related to the evaluation of combined modality therapy. Reports that patients have superior outcome in single-arm studies as compared to historical controls treated with radiation alone have limited value because of several types of bias including patient selection, stage migration, the tendency to publish positive results, or inadequate follow-up as compared to the historical series. The observation that response to chemotherapy predicts for survival after combined treatment also conveys no proof that combined treatment is superior to radiation alone. Randomized controlled trials provide the only rigorous method for evaluating combined therapy, but are also subject to misinterpretation. The majority of published trials report negative results but are too small to detect clinically important differences in survival. Even large trials may give spurious results if they seek small benefits of treatment in a spectrum of patients with widely differing prognosis. Some randomized trials have demonstrated improved local control and increased toxicity from combined treatment, a result that might have been achieved by increasing the effective radiation dose. Ideally, combined treatment should be compared with radiotherapy alone at equal levels of normal tissue damage. A review of published data for patients with cancers of the head and neck, lung, gastrointestinal tract and bladder reveals very few trials which have adequately evaluated the role of combined modality therapy (with or without surgery). Most of the large randomized trials have demonstrated no benefit from the use of radiation and chemotherapy, although some of them suggest small therapeutic gains from using thoracic radiation with chemotherapy in small-cell-lung cancer of limited extent, or from combined modality treatment after resection of rectal cancer. Possible reasons for the failure of active drugs to lead to easily detected gains in therapeutic index include insufficient reduction in cell survival from chemotherapy, selective killing of radiosensitive subpopulations, stimulation of the proliferation of surviving cells, or enhancement of metastasis. With the possible exception of radiation and concurrent 5-fluorouracil for squamous cancers of the anal canal, there are no convincing data to mandate the routine combined use of radiotherapy and chemotherapy in any of the above sites.

Hypoxia induces DNA overreplication and enhances metastatic potential of murine tumor cells

Cultured cells subjected to oxygen deprivation have been shown to undergo anomalous DNA synthesis, which can result in DNA overreplication and the generation of cellular variants [Rice, G. C., Hoy, C. & Schimke, R. T. (1986) Proc. Natl. Acad. Sci. USA 83, 5978-5982]. In the present study, murine tumor cells were exposed to severe hypoxia and then tested for their ability to form experimental metastases. Upon reoxygenation, cells transiently, yet dramatically, increased their metastatic potential. Flow cytometric analysis confirmed that hypoxia and reoxygenation induced cell cycle perturbations and DNA overreplication in these tumor cell lines. Fibrosarcoma cells with overreplicated DNA isolated by fluorescence-activated cell sorting proved to be highly metastatic, although cells with 2-4 times the haploid DNA content in populations treated with hypoxia were also markedly more metastatic than oxic populations. These results support the hypothesis that hypoxic conditions existing in regions of solid tumors promote cellular heterogeneity and tumor progression.

Can cancer chemotherapy enhance the malignant behaviour of tumours?

Cancer chemotherapy is currently undergoing an intensive reappraisal because of its unimpressive performance against the major common cancers. There are a number of possible reasons for this lack of success; one considered here is that under some circumstances anti-neoplastic drug treatment actually increases the malignant behaviour of tumours. Support for this idea comes mainly from experimental studies in which drug treatments increased metastatic spread. Investigation of this phenomenon shows that drug induced modifications of the host, including immunosuppression and vascular damage, can indeed facilitate metastasis. In addition, new data are presented demonstrating that the direct action of drugs on the tumour cells themselves can have similar enhancing effects. The possible mechanisms underlying such direct effects are discussed and the ability of anti-cancer drugs to cause genetic mutations, amplify genes, and alter gene expression are considered. While the nature and extent of this facilitation of tumour malignancy is not fully understood, it is suggested that this possibility should be considered in the design of treatment protocols.