Late Effects of Childhood Cancer: Life-threatening Issues

Demystifying the Relationship Between Metformin, AMPK, and Doxorubicin Cardiotoxicity

Doxorubicin (DOX) is an extremely effective and wide-spectrum anticancer drug, but its long-term use can lead to heart failure, which presents a serious problem to millions of cancer survivors who have been treated with DOX. Thus, identifying agents that can reduce DOX cardiotoxicity and concurrently enhance its antitumor efficacy would be of great clinical value. In this respect, the classical antidiabetic drug metformin (MET) has stood out, appearing to have both antitumor and cardioprotective properties. MET is proposed to achieve these beneficial effects through the activation of AMP-activated protein kinase (AMPK), an essential regulator of mitochondrial homeostasis and energy metabolism. AMPK itself has been shown to protect the heart and modulate tumor growth under certain conditions. However, the role and mechanism of the hypothesized MET-AMPK axis in DOX cardiotoxicity and antitumor efficacy remain to be firmly established by in vivo studies using tumor-bearing animal models and large-scale prospective clinical trials. This review summarizes currently available literature for or against a role of AMPK in MET-mediated protection against DOX cardiotoxicity. It also highlights the emerging evidence suggesting distinct roles of the AMPK subunit isoforms in mediating the functions of unique AMPK holoenzymes composed of different combinations of isoforms. Moreover, the review provides a perspective regarding future studies that may help fully elucidate the relationship between MET, AMPK and DOX cardiotoxicity.

Doxorubicin-induced cardiomyocyte death is mediated by unchecked mitochondrial fission and mitophagy

Doxorubicin (Dox) is a widely used antineoplastic agent that can cause heart failure. Dox cardiotoxicity is closely associated with mitochondrial damage. Mitochondrial fission and mitophagy are quality control mechanisms that normally help maintain a pool of healthy mitochondria. However, unchecked mitochondrial fission and mitophagy may compromise the viability of cardiomyocytes, predisposing them to cell death. Here, we tested this possibility by using Dox-treated H9c2 cardiac myoblast cells expressing either the mitochondria-targeted fluorescent protein MitoDsRed or the novel dual-fluorescent mitophagy reporter mt-Rosella. Dox induced mitochondrial fragmentation as shown by reduced form factor, aspect ratio, and mean mitochondrial size. This effect was abolished by short interference RNA-mediated knockdown of dynamin-related protein 1 (DRP1), a major regulator of fission. Importantly, DRP1 knockdown decreased cell death as indicated by the reduced number of propidium iodide-positive cells and the cleavage of caspase-3 and poly (ADP-ribose) polymerase. Moreover, DRP1-deficient mice were protected from Dox-induced cardiac damage, strongly supporting a role for DRP1-dependent mitochondrial fragmentation in Dox cardiotoxicity. In addition, Dox accelerated mitophagy flux, which was attenuated by DRP1 knockdown, as assessed by the mitophagy reporter mt-Rosella, suggesting the necessity of mitochondrial fragmentation in Dox-induced mitophagy. Knockdown of parkin, a positive regulator of mitophagy, dramatically diminished Dox-induced cell death, whereas overexpression of parkin had the opposite effect. Together, these results suggested that Dox cardiotoxicity was mediated, at least in part, by the increased mitochondrial fragmentation and accelerated mitochondrial degradation by the lysosome. Strategies that limit mitochondrial fission and mitophagy in the physiologic range may help reduce Dox cardiotoxicity.-Catanzaro, M. P., Weiner, A., Kaminaris, A., Li, C., Cai, F., Zhao, F., Kobayashi, S., Kobayashi, T., Huang, Y., Sesaki, H., Liang, Q. Doxorubicin-induced cardiomyocyte death is mediated by unchecked mitochondrial fission and mitophagy.

Stage- and tissue-specific effect of cyclophosphamide during tooth development

OBJECTIVE

The aim of this study was to investigate the toxic effect of cyclophosphamide (CPA) in the development of rodent molars.

METHODS

CPA was administered intraperitoneally in postnatal mice between Day 1 and Day 10, and the morphological phenotype was evaluated at Day 26 using micro-computed tomography and histological analysis, including cell proliferation and cell death analyses.

RESULTS

M3 molars of the mice who received 100 mg/kg CPA treatment at Day 6 or M2 molars who received treatment at Day 1 resulted in tooth agenesis or marked hypoplasia. Histological observation demonstrated that CPA treatment at Day 6 resulted in shrinkage of the M3 tooth germs, with a significant reduction in the proliferation of apoptotic cells. Conversely, CPA exposure at Day 2, which occurs at around the bud stage of M3, resulted in crown and root hypoplasia, with reduced numbers of cusp and root. In addition, CPA exposure at Day 10, which is the late bell stage of M3, induced root shortening; however, it did not affect crown morphogenesis.

LIMITATIONS

The timing of CPA administration is limited to after birth. Therefore, its effect during the early stages of M1 and M2 could not be investigated.

CONCLUSION

Defective phenotypes were evident in both crown and roots due to the effect of CPA. Interestingly, the severity of the phenotypes was associated with the developmental stages of the tooth germs at the time of CPA administration. The cap/early bell stage is the most susceptive timing for tooth agenesis, whereas the late bell stage is predominantly affected in terms of root formation by CPA administration.

Factors associated with the specific worries of childhood cancer survivors: Cross-sectional survey in Japan

BACKGROUND

Previous research has shown that adult childhood cancer survivors (CCS) have many worries. We re-analyzed the employment data in order to identify these worries and their associated factors.

METHODS

The participants were selected from the membership directory of Heart Link mutual-aid health insurance, and recruited by the CCS Network. We conducted a cross-sectional survey (a self-rated questionnaire on employment) via post or email with a link to an Internet website. We investigated the association between CCS factors and the specific worries. The adjusted odds ratios (OR) for the associated factors with a specific worry were estimated on logistic regression analysis.

RESULTS

A total of 240 questionnaires were collected by November 2012. One questionnaire was excluded because the answers were not provided by the CCS him/herself. The most common worries were health-related problems (50%) and employment issues (40%), which were followed by his/her personality and life (23%) and self-appearance (20%). Fifty (21%) out of 239 CCS answered no specific worry. The common consistent factor associated with worries was the presence of late effects. Of note was that the CCS worries were not associated with age at diagnosis or follow up, gender, educational achievement or marriage. The worry about employment issues was associated with economic status, disability qualification, and employment status.

CONCLUSIONS

The CCS worries were strongly affected by the presence of late effects. No significant association was noted between CCS worries and gender, age at diagnosis or follow up, or educational achievements. Economic status and disability qualification were associated with some worries.

Cyclophosphamide-Induced Morphological Changes in Dental Root Development of ICR Mice

Background

Survivors of childhood cancer are at risk of late dental development. Cyclophosphamide is one of the most commonly used chemotherapeutic agents against cancer in children. The aim of this study was to investigate the effects of cyclophosphamide on root formation in the molars of growing mice and to assess the morphological changes in these roots using three-dimensional structural images.

Methods

We treated 16 12-day-old ICR mice with cyclophosphamide (100 mg/kg, i.p.) and 16 control mice with saline. At 16, 20, 24, and 27 days of age, the mandibular left first molars were scanned using soft micro-computed tomography. After scanning, the structural indices were calculated using a three-dimensional image analysis system, and the images were subjected to three-dimensional reconstruction. The length and apical foramen area of all distal roots were assessed. Histological changes in the apical region were then assessed via hematoxylin and eosin staining.

Results

The mandibular molars of all experimental mice showed evidence of cytotoxic injury, which appeared in the form of anomalous root shapes. Although all roots developed further after cyclophosphamide injection, the three-dimensional structural images showed that the roots in the experimental group tended to develop more slowly and were shorter than those in the control group. At 27 days of age, the mean root length was shorter in the experimental group than in the control group. Conversely, the apical foramen of the roots in the experimental group tended to close faster than that of roots in the control group. In addition, hematoxylin and eosin staining of the distal roots in the experimental group showed increased dentin thickness in the apical region.

Conclusion

Our results suggest that cyclophosphamide can result in short root lengths and early apical foramen closure, eventually leading to V-shaped or thin roots.

Recent employment trend of childhood cancer survivors in Japan: a cross-sectional survey

BACKGROUND

Previous research has shown that some adult childhood cancer survivors (CCSs) have experienced employment difficulties. However, the actual employment status of CCSs in Japan has not been studied.

PARTICIPANTS AND METHODS

The participants were selected from the membership directory of Heart Link mutual-aid health insurance and recruited by the Childhood Cancer Patients' Network. We conducted a cross-sectional survey (a self-rated questionnaire on employment) via postal mail or an email communication with a link to an Internet website. We explored the association between the characteristics of CCSs who require disability qualification and having experienced unemployment. The adjusted odds ratios (ORs) for the factors with an outcome of interest were estimated with logistic regression analysis.

RESULTS

In total, 44 CCSs indicated that they had a disability qualification. The significant independent factors related to needing a disability qualification were late effects [OR 12.3; 95 % confidence interval (CI) 3.37-45.2], brain tumors (OR 9.55; 95 % CI 1.90-48.0), and being a high school graduate (OR 9.86; CI 2.67-36.4). The unemployment rate was 15.9 % among CCSs, excluding homemakers and students. Approximately 70 % of unemployed CCSs had some late effects; independent factors related to unemployment were late effects (OR 6.22; 95 % CI 1.80-21.40), dropping out of school (OR 8.46; 95 % CI 1.66-43.10), and brain tumors (OR 2.73; 95 % CI 0.83-8.96). Most unemployed CCSs were likely to seek work, despite their health problems.

CONCLUSIONS

The unemployment rate is not high in Japan, but some CCSs need extended disability qualification. The independent factors related to unemployment were late effects and dropping out of school.

Tongue cancer in young patients: case report of a 26-year-old patient

Introduction

This article presents the case of a 26-year-old woman with tongue cancer. The median age at the diagnosis of the tongue’s cancer is 61 years. Only approximately 2% of patients are diagnosed before the age of 35.

Case presentation

Our patient survived acute myeloid leukemia (AML) before her second year. She had been having recurrent, poorly healing aphtae on the right side of the tongue for a period of months before the symptoms of the tongue cancer appeared. As a treatment a partial glossectomy was conducted on the right side and a neck dissection of levels I-III. Than a reconstruction of the tongue with a radialis free vascularised flap from left side was performed.

Discussion

It should be always looked for the causal factor in young patients with a neoplasm. There is strong evidence for second malignant neoplasms in survivors of childhood cancer.

Physician preferences and knowledge regarding the care of childhood cancer survivors in Japan: a mailed survey of the Japanese Society of Pediatric Oncology

OBJECTIVE

Japanese physicians' attitudes regarding the health-care needs of young adult childhood cancer survivors (CCSs) are not well described. Thus, we examined the self-reported preferences and knowledge of pediatric oncologists and surgeons.

METHODS

A mailed survey was sent to 858 physician members of the Japanese Society of Pediatric Oncology. We compared the responses of pediatric oncologists and pediatric surgeons.

RESULTS

The pediatric oncologists' response rate was 56% (300 out of 533) and that of pediatric surgeons 32% (105 out of 325). The median age of respondents was 46 and 48 years, respectively; 79 and 84% were men. When comfort levels in caring for CCSs were described (i.e. 1 = very uncomfortable; 7 = very comfortable), the mean levels were 4.4 and 3.8 with CCSs ≤ 21 years, 3.6 and 3.6 with 21 years < CCSs ≤ 30 years, and 2.8 and 3.3 with CCSs > 30 years, respectively. In clinical vignette questions, 62% of the pediatric oncologists and 43% of the surgeons answered three or more questions appropriately. Pediatric surgeons reported significantly lower familiarity with long-term follow-up guidelines than pediatric oncologists. Most pediatric oncologists and many surgeons conducted truth-telling of cancer diagnosis to adult CCSs now. They thought that the most important issues are an original long-term follow-up guideline suitable for the Japanese situation and collaborations with adult-based general physicians.

CONCLUSIONS

Many Japanese pediatric oncologists are uncomfortable with caring for survivors as they age and have suboptimal knowledge regarding late effects. The change in truth-telling situation and preference for collaboration with adult-based physicians was demonstrated also in Japan.

Autologous hematopoietic stem cell transplantation following high-dose chemotherapy for non-rhabdomyosarcoma soft tissue sarcomas

BACKGROUND

Soft tissue sarcomas (STS) are a highly heterogeneous group of rare malignant solid tumors. Non-rhabdomyosarcoma soft tissue sarcomas (NRSTS) comprise all STS except rhabdomyosarcoma. In patients with advanced local or metastatic disease, autologous hematopoietic stem cell transplantation (HSCT) applied after high-dose chemotherapy (HDCT) is a planned rescue therapy for HDCT-related severe hematologic toxicity.

OBJECTIVES

To assess the effectiveness and safety of HDCT followed by autologous HSCT for all stages of soft tissue sarcomas in children and adults.

SEARCH STRATEGY

We searched the electronic databases CENTRAL (The Cochrane Library 2010, Issue 2), MEDLINE and EMBASE (February 2010). Online trial registers, congress abstracts and reference lists of reviews were searched and expert panels and authors were contacted.

SELECTION CRITERIA

Terms representing STS and autologous HSCT were required in the title, abstract or keywords. In studies with aggregated data, participants with NRSTS and autologous HSCT had to constitute at least 80% of the data. Comparative non-randomized studies were included because randomized controlled trials (RCTs) were not expected. Case series and case reports were considered for an additional descriptive analysis.

DATA COLLECTION AND ANALYSIS

Study data were recorded by two review authors independently. For studies with no comparator group, we synthesised results for studies reporting aggregate data and conducted a pooled analysis of individual participant data using the Kaplan-Meyer method. The primary outcomes were overall survival (OS) and treatment-related mortality (TRM).

MAIN RESULTS

We included 54 studies, from 467 full texts articles screened (11.5%), reporting on 177 participants that received HSCT and 69 participants that received standard care. Only one study reported comparative data. In the one comparative study, OS at two years after HSCT was estimated as statistically significantly higher (62.3%) compared with participants that received standard care (23.2%). In a single-arm study, the OS two years after HSCT was reported as 20%. In a pooled analysis of the individual data of 54 participants, OS at two years was estimated as 49% (95% CI 34% to 64%). Data on TRM, secondary neoplasia and severe toxicity grade 3 to 4 after transplantation were sparse. All 54 studies had a high risk of bias.

AUTHORS' CONCLUSIONS

Due to a lack of comparative studies, it is unclear whether participants with NRSTS have improved survival from autologous HSCT following HDCT. Owing to this current gap in knowledge, at present HDCT and autologous HSCT for NRSTS should only be used within controlled trials.

Pediatric Cancer: A Comprehensive Review. Part I: Biology, Epidemiology, Common Tumours, Principles of Treatment and Late Effects

The incidence rates of pediatric cancer, like adult cancer, are increasing, though to a lesser degree. Options for the treatment of childhood cancers are continually changing and improving and overall survival has increased dramatically over the last 60 years. This paper discusses the incidence and survival trends of childhood cancer. The biology and epidemiology of the most common cancers seen in children and the late effects of treatment for childhood cancer will also be discussed. A basic understanding of childhood cancer is important for both hospital and community pharmacists, since many young adults in North America are now survivors of childhood cancer and may experience long-term consequences of chemotherapy.