Clinical pathological characteristics of breast cancer patients with secondary diabetes after systemic therapy: a retrospective multicenter study

Immune checkpoint inhibitors-related endocrinopathies exhibit increased severity in breast cancer patients: a real-world study

PURPOSE

This study aims to systematically evaluate the incidence of immune checkpoint inhibitors (ICIs)-related endocrinopathies and their onset time in patients with breast cancer (BC) in a real-world setting.

METHODS

An analysis was conducted on the medical records of 122 BC patients who underwent ICIs therapy at the Department of Breast Surgery, Guangdong Provincial People's Hospital, from April 2019 to September 2021. Follow-up data continued until October 2022.

RESULTS

The research indicated that 60.66% of BC patients experienced ICI-related endocrinopathies. The endocrinopathies included pituitary injury (7.38%), primary thyroid dysfunction (34.43%), supranormal fasting blood glucose or glycohemoglobin levels (16.39%), and adrenal injury (2.46%). Subgroup analyses were further performed based on clinical characteristics, demonstrated variability in the incidence of ICI-related endocrinopathies. Notably, subpopulations harboring genetic mutations exhibited a markedly higher prevalence of hypophysitis, as evidenced by a statistically significant association (P = 0.022). Similarly, individuals with HER2 positivity were found to have a significantly increased incidence of pancreatic islet injury (P = 0.023). Moreover, the study documented that the median onset times of ICIs-related endocrinopathies in pituitary, thyroid, pancreatic, and adrenal damage were 264, 184, 99 and 141 days, respectively, which were substantially longer compared to previous reports involving other tumors. Remarkably, even after 500 days of initiating ICI therapy, new cases of ICI-related endocrine disorders continue to emerge, suggesting a situation of delayed onset of ICI-related endocrinopathies in BC patients.

CONCLUSION

The retrospective analysis confirmed a higher incidence and longer median onset time of ICI-related endocrinopathies in BC patients compared to other cancers. These outcomes underscore the critical need for regular and extended monitoring of endocrine functions in BC patients receiving ICI therapy, advocating for personalized monitoring approaches based on individual clinical profiles.

Incident diabetes among older Asian, Native Hawaiian, and Pacific Islander women with breast cancer

BACKGROUND

The risk of diabetes among Asian, Native Hawaiian, and Pacific Islander (ANHPI) women after breast cancer is unclear. This study estimated the risk of incident type II diabetes in older ANHPI and older non-Hispanic White (NHW) women with breast cancer from the US National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Medicare linked claims.

METHODS

A matched cohort of 7122 older ANHPI and 21 365 older NHW women with breast cancer were identified from SEER-Medicare between 2000 and 2017. To assess the risk of incident type II diabetes after breast cancer, hazard ratios (HRs) and 95% confidence intervals (95% CI) were estimated using the Cox proportional-hazards regression model.

RESULTS

During the mean 8 years of follow-up, 9.3% of older women with breast cancer developed incident type II diabetes. In comparison with older NHW women, older ANHPI women without a known history of diabetes had an elevated risk of diabetes after breast cancer, with strong associations observed for Pacific Islander (HR = 3.09, 95% CI = 1.43 to 6.67), Vietnamese (HR = 2.12, 95% CI = 1.33 to 2.36), and Filipino (HR = 2.02, 95% CI = 1.57 to 2.59) women with breast cancer, adjusting for potential confounders. Among ANHPI women with breast cancer, more baseline comorbidities and obesity were risk factors for developing incident type II diabetes.

CONCLUSION

ANHPI women diagnosed with breast cancer had an elevated risk of type II diabetes compared with older NHW women with breast cancer. Routine monitoring and management of diabetes are warranted in older ANHPI women with breast cancer.

Mitochondrial ALDH2 improves ß-cell survival and function against doxorubicin-induced apoptosis by targeting CK2 signaling

AIMS

The aim of this study was to better understand how the chemotherapy drug doxorubicin contributes to the development of β-cell dysfunction and to explore its relationship with mitochondrial aldehyde dehydrogenase-2 (ALDH2).

MATERIALS AND METHODS

In order to investigate this hypothesis, doxorubicin was administered to INS-1 cells, a rat insulinoma cell line, either with or without several target protein activators and inhibitors. ALDH2 activity was detected with a commercial kit and protein levels were determined with western blot. Mitochondrial ROS, membrane potential, and lipid ROS were determined by commercial fluorescent probes. The cell viability was measured by CCK-assay.

RESULTS

Exposure of INS-1 cells to doxorubicin decreased active insulin signaling resulting in elevated ALDH2 degradation, compared with control cells by the induction of acid sphingomyelinase mediated ceramide induction. Further, ceramide induction potentiated doxorubicin induced mitochondrial dysfunction. Treatment with the ALDH2 agonist, ALDA1, blocked doxorubicin-induced acid sphingomyelinase activation which significantly blocked ceramide induction and mitochondrial dysfunction mediated cell death. Treatment with the ALDH2 agonist, ALDA1, stimulated casein kinase-2 (CK2) mediated insulin signaling activation. CK2 silencing neutralized the function of ALDH2 in the doxorubicin treated INS-1 cells.

CONCLUSIONS

Mitochondrial ALDH2 activation could inhibit the progression of doxorubicin induced pancreatic β-cell dysfunction by inhibiting the acid sphingomyelinase induction of ceramide, by regulating the activation of CK2 signaling. Our research lays the foundation of ALDH2 activation as a therapeutic target for the precise treatment of chemotherapy drug induced β-cell dysfunction.

Screening and Management Recommendations for Type 2 Diabetes in Women With Breast Cancer

Breast cancer increases the risk of type 2 diabetes 1.07- to 4.27-fold, depending on patient and treatment characteristics, such as postmenopausal status, hormone therapy, and treatment with adjuvant chemotherapy. We evaluated the current evidence and considered the role of increased screening for type 2 diabetes in this at-risk population. This narrative review was conducted using Embase and MEDLINE databases. Keywords including diabetes and breast cancer were used. Articles were limited to those published in English between 2000 and 2022. It appears that the increased risk of diabetes begins at or just after breast cancer diagnosis, and remains elevated for at least 10 to 15 years, with greatest risk in the first 2 years after diagnosis. Subsets of patients with breast cancer appear to be at higher risk of developing type 2 diabetes, including those who were treated with adjuvant chemotherapy or hormone therapy. Further investigation is needed to develop specific screening recommendations for this population. If screening is performed with a glycated hemoglobin test during breast cancer treatment, then hemoglobin should be measured at the same time given the association of breast cancer therapy with anemia. Presence of breast cancer should not be a major factor when choosing among available antihyperglycemic agents. Overall, patients with breast cancer appear to be at an increased risk of developing type 2 diabetes. This increased risk suggests the need for further investigation to develop specific screening recommendations for this at-risk population.

Hypertension and hyperglycaemia are positively correlated with local invasion of early cervical cancer

Background

Metabolic disorders are involved in the development of numerous cancers, but their association with the progression of cervical cancer is unclear. This study aims to investigate the association between metabolic disorders and the pathological risk factors and survival in patients with early cervical cancer.

Methods

Patients with FIGO IB1 (2009) primary cervical cancer who underwent radical hysterectomy and systematic pelvic lymph node dissection at our institution from October 2014 to December 2017 were included retrospectively. Clinical data regarding the metabolic syndrome and surgical pathology of the patient were collected. The correlations between metabolic disorders (hypertension, hyperglycemia, and obesity) and clinicopathological characteristics as well as survival after surgery were analyzed.

Results

The study included 246 patients with clinical IB1 cervical cancer, 111 (45.1%) of whom had at least one of the comorbidities of hypertension, obesity, or hyperglycemia. Hypertension was positively correlated with parametrial invasion and poorly differentiated histology; hyperglycemia was positively correlated with stromal invasion; obesity was negatively associated with lymph node metastasis; but arbitrary disorder did not show any correlation with pathologic features. Hypertension was an independent risk factor for parametrial invasion (OR=6.54, 95% CI: 1.60-26.69); hyperglycemia was an independent risk factor for stromal invasion (OR=2.05, 95% CI: 1.07-3.95); and obesity was an independent protective factor for lymph node metastasis (OR=0.07, 95% CI: 0.01-0.60). Moreover, the patients with hypertension had a significantly lower 5-year OS rate (70.0% vs. 95.3%, P<0.0001) and a significantly lower 5-year PFS rate than those without hypertension (70.0% vs. 91.2%, P=0.010).

Conclusion

Hypertension and hyperglycemia are positively associated with local invasion of early cervical cancer, which need to be verified in multi-center, large scale studies.

Breast cancer and incidence of type 2 diabetes mellitus: a systematic review and meta-analysis

PURPOSE

Breast cancer and its treatments may increase the risk of type 2 diabetes (T2D). We conducted a systematic review and meta-analysis to investigate the association between breast cancer and the incidence of T2D overall, and according to breast cancer treatments.

METHODS

We searched PubMed, Embase and references of relevant papers for studies on breast cancer, breast cancer treatment, and subsequent T2D risk. Using random-effects models, we calculated effect estimates and associated 95% confidence intervals of the association between breast cancer, adjuvant breast cancer treatments (i.e., endocrine therapy (tamoxifen, aromatase inhibitors, and combined) and chemotherapy), and subsequent T2D. We used funnel plots to assess publication bias.

RESULTS

Among 15 eligible studies, 10 reported on T2D risk after breast cancer, chemotherapy, or endocrine therapy; five studies investigated more than one association. Compared with patients without breast cancer, those with breast cancer and those who received any endocrine therapy had elevated risk of incident T2D (EE = 1.23, 95% CI = 1.13-1.33 and EE = 1.23, 95% CI = 1.16-1.32, respectively). Among breast cancer patients only, the risk of T2D was higher for those who received tamoxifen compared with those who did not receive tamoxifen (EE = 1.28, 95% CI = 1.18-1.38). Due to few studies, analyses investigating T2D risk after treatment with aromatase inhibitors or chemotherapy were inconclusive.

CONCLUSION

Our findings suggest an elevated risk of T2D in breast cancer survivors, particularly after tamoxifen therapy. Further research is needed to determine the impact of aromatase inhibitors, and chemotherapy on the incidence of T2D after breast cancer.

The chemotherapeutic drug doxorubicin does not exacerbate p16Ink4a-positive senescent cell accumulation and cardiometabolic disease development in young adult female LDLR-deficient mice

Cancer survivors who received chemotherapy, such as the anthracycline doxorubicin (DOX), have an increased risk of developing complications later in life, including the development of chronic metabolic diseases. Although the etiology of this increased risk for late metabolic complications in cancer survivors is poorly understood, a causal role of therapy-induced senescent cells has been suggested. To study the role of cellular senescence in chemotherapy-induced metabolic complications, young adult female low-density lipoprotein receptor-deficient (Ldlr^-/-)-p16-3MR mice, in which p16^Ink4a-positive (p16^Ink4a+) senescent cells can be genetically eliminated, were treated with four weekly injections of DOX (2.5 mg/kg) followed by a high-fat high-cholesterol diet for 12 weeks. While DOX treatment induced known short-term effects, such as reduction in body weight, gonadal fat mass, and adipose tissue inflammation, it was not associated with significant long-term effects on glucose homeostasis, hepatic steatosis, or atherosclerosis. We further found no evidence of DOX-induced accumulation of p16^Ink4a+-senescent cells at 1 or 12 weeks after DOX treatment. Neither did we observe an effect of elimination of p16^Ink4a+-senescent cells on the development of diet-induced cardiometabolic complications in DOX-treated mice. Other markers for senescence were generally also not affected except for an increase in p21 and Cxcl10 in gonadal white adipose tissue long-term after DOX treatment. Together, our study does not support a significant role for p16^Ink4a+-senescent cells in the development of diet-induced cardiometabolic disease in young adult DOX-treated female Ldlr^-/- mice. These findings illustrate the need of further studies to understand the link between cancer therapy and cardiometabolic disease development in cancer survivors.

Link between Blood Cell-Associated Inflammatory Indices and Chemotherapy-Induced Hyperglycemia in Women Affected with Breast Cancer: Clinical Studies

Krishna PrasadBackground  Development of treatment-induced hyperglycemia/diabetes is a considerable problem in women undergoing chemotherapy for breast cancer. In this study, baseline levels of blood cell-associated inflammatory indices (BCAII) were analyzed to understand their role in the development of treatment-induced hyperglycemia and diabetogenesis. Materials and Methods  This was a retrospective study, and information on women who were normoglycemic and nondiabetic and of women who were diabetic at the beginning of the treatment were collected from files. Demographic, pathology-related details, and complete blood profile were noted. Neutrophil-to-lymphocyte ratio (NLR), derived neutrophil-to-lymphocyte ratio (dNLR), platelet-to-lymphocyte ratio (PLR), and systemic inflammatory index (SII) which indicate BCAII were calculated. Demographic details were subjected to frequency and percentage, while blood parameters were subjected to one-way analysis of variance followed by post hoc Bonferroni's multiple comparison tests. A p -value of <0.05 was considered significant. Results  The results indicated that a significant difference in levels of total count ( p  < 0.035), neutrophil, lymphocyte, and platelets ( p  < 0.001) were observed. Regarding BCAII, when compared with women who were normoglycemic at the end of treatment, NLR, dNLR, PLR, and SII were significantly high for people who were known diabetics at the beginning of treatment ( p  < 0.001). The dNLR ( p  = 0.0008), PLR ( p  < 0.001), and SII ( p  < 0.001) were significant for people who developed secondary hyperglycemia/diabetes, while only dNLR was significant for people who progressed from normal to prediabetes stage ( p  = 0.049) Conclusion  To the best of the authors' knowledge, this is the first study that indicates difference in baseline BCAII and development of treatment-induced hyperglycemia/diabetes indicating that underlying low levels of inflammation may contribute to diabetogenesis in women affected with breast cancer.

Higher Incidence of Diabetes in Cancer Patients Compared to Cancer-Free Population Controls: A Systematic Review and Meta-Analysis

Background: Diabetes increases the risk of certain types of cancer. However, the literature regarding the incidence of diabetes after cancer diagnosis is inconsistent. We aimed to assess whether there was a higher incidence of diabetes among cancer patients by performing a systematic review and meta-analysis of results from cohort studies. Methods: A systematic electronic literature search was carried out from cohort studies regarding the incidence of diabetes in cancer patients, using the databases PubMed (MEDLINE), Embase, Web of Science, and the Cochrane Library. Random-effects meta-analyses were conducted to pool the estimates. Results: A total of 34 articles involving 360,971 cancer patients and 1,819,451 cancer-free controls were included in the meta-analysis. An increased pooled relative risk (RR) of 1.42 (95% confidence interval (CI): 1.30−1.54, I2 = 95, τ2 = 0.0551, p < 0.01) for diabetes in cancer patients was found compared with the cancer-free population. The highest relative risk was observed in the first year after cancer diagnosis (RR = 2.06; 95% CI 1.63−2.60). Conclusions: New-onset diabetes is positively associated with cancer, but this association varies according to cancer type. More prospective studies with large sample sizes and longer follow-up times are advocated to further examine the association and the underlying mechanisms.

Evaluation of lifestyle risk factor differences in global patterns of breast cancer mortality and DALYs during 1990-2017 using hierarchical age-period-cohort analysis

BACKGROUND

Statistical evidence on breast cancer (BC) burden related to health and lifestyle risk factors are valuable for health policy-making. This study aimed to compare the trends in BC mortality and disability adjusted life years (DALYs) attributable to various health and life style risk factors among different world's regions according to sociodemographic index (SDI).

METHODS

We extracted the age-standardized and age-specific rate of mortality and DALYs of women BC during 1990-2017 using the comparative risk assessment framework of the 2017 global burden of disease (GBD) study. We performed hierarchical age-period-cohort analysis to estimate age- and time-related trends, and effect of interactions between different risk factors on BC risk.

RESULTS

During 1990-2017, the age-standardized rate of mortality and DALYs of women BC was increasing in less developed and under developing regions. The risk factor alcohol use [RR 51.3(95%CI 17.6-149.7)] and smoking [5.9(2.0-17.3)] were significantly highly contributor to increased mortality risk in high SDI region. Whereas in the low-SDI region, the greater mortality risk was observed in alcohol use [6.9(2.4-17)] and high FPG [2.7(1.5-3.1)]-related deaths. The adjusting for individual age, period, and risk factor effects, the significant interaction effect between metabolic risk factors and older ages were observed in all SDI regions and globally as well. However, an increasing cohort effect of alcohol, high fasting plasma glucose (FPG) and smoking-related death, and DALYs was observed during 1960 to 1985 cohorts among low-SDI regions.

CONCLUSIONS

The age-standardized rates of mortality and DALYs due to BC has been increasing in low-SDI region. Alcohol consumption, high body mass index (BMI), high FPG, and smoking are potential BC risk factors particularly in older ages that leading to adverse disease outcomes. Therefore, rapid aging and prevalence of these prospective risk factors may strengthen the increasing mortality and DALYs of BC in low-SDI region. Hence, preventive measure along with strict action against concerned BC risk factors should be taken to reduce the disease burden specifically among lower-SDI regions.

Breast cancer and the renin-angiotensin system (RAS): Therapeutic approaches and related metabolic diseases

The Renin-Angiotensin System (RAS) is classically recognized for regulating blood pressure and fluid balance. Recently, this role has extended to other areas including inflammation, obesity, diabetes, as well as breast cancer. RAS components are expressed in normal and cancerous breast tissues, and downregulation of RAS inhibits metastasis, proliferation, angiogenesis, and desmoplasia in the tumor microenvironment. Therefore, RAS inhibitors (Angiotensin receptor blockers, ARBs, or angiotensin converting enzyme inhibitors, ACE-I) may be beneficial as preventive adjuvant therapies to thwart breast cancer development and improve outcomes, respectively. Given the beneficial effects of RAS inhibitors in metabolic diseases, which often co-exist in breast cancer patients, combining RAS inhibitors with other breast cancer therapies may enhance the effectiveness of current treatments. This review scrutinizes above associations, to advance our understanding of the role of RAS in breast cancer and its potential for repurposing of RAS inhibitors to improve the therapeutic approach for breast cancer patients.

Incidence of Hyperglycemia/Secondary Diabetes in Women who have Undergone Curative Chemotherapy for Breast Cancer: First Study from India

Purpose  Development of cancer chemotherapy treatment-induced hyperglycemia/ diabetes (secondary diabetes) is a major problem and has never been reported from India. The present study was planned to ascertain this in women undergoing curative chemotherapy for their breast cancer. Materials and Methods  This was a retrospective chart-based study and was conducted in a cancer specialty hospital. The information on women who were nondiabetic at the start of the treatment was collected from the files. Details on cancer diagnosis, domicile, body mass index (BMI), type of diet, marital status, number of children, and previous history of diabetes if any were considered. The blood glucose levels before surgery and after the completion of radiotherapy were considered. World Health Organization (WHO) guidelines for diabetes were considered. The data were subjected to frequency and percentage and analyzed using Chi-square test. Association between the demographic details and development of Hyperglycemia or secondary diabetes or prediabetes was done using the Pearson's correlation analysis. p < 0.05 was considered as statistically significant. Results  A total of 474 cases were included in accordance with the inclusion criteria. The results indicated that by the end of the radiation treatment, 24.89% were prediabetic, 10.97% were diabetic after being in prediabetic stage, 8.22% became diabetic without going through a prediabetic stage, and that 55.91% did not develop either prediabetic or diabetic condition. Analysis of development of secondary diabetes and prediabetes with BMI ( p < 0.0001) and age ( p < 0.024) showed a strong correlation and was significant. Conclusion  To the best of the authors' knowledge, this is the first study from India, and the results indicate that the development of secondary diabetes in women undergoing curative chemotherapy is high. Attempts are underway to ascertain the cause for the development and how it can be mitigated.

A simple screening score to predict diabetes in cancer patients: A Korean nationwide population-based cohort study

Many cancer patients develop diabetes, which may result in reduction of chemotherapy effectiveness and increased infection risk and cardiovascular mortality. Diabetes may also increase the risks of chemotherapy-related toxicity and post-operative mortality, or represent an obstacle to optimal cancer treatment. However, the clinical predictors of diabetes in cancer patients remain largely unknown. Therefore, the aim of our study was to evaluate the risk factors for developing diabetes and construct a nomogram to predict diabetes in cancer patients.We investigated patients from a national sample cohort obtained from the Korea National Health Insurance Service (KNHIS), which included 2% of the Korean population. Patients who had undergone routine medical evaluation by the KNHIS between 2004 and 2008 and been hospitalized due to cancer (ICD-10 codes C00-97) during the past 3 years were included. After excluding patients with type 2 diabetes and missing data, 10,899 patients were enrolled and followed-up until 2013. A total of 7630 (70%) patients were assigned as the training cohort and used to construct the nomogram which was based on a multivariable logistic regression model. The remaining patients (n = 3269) were used as the validation cohort.The incidence rate of diabetes was 12.1 per 1000 person-years over a mean follow-up of 6.6 ± 1.8 years. Significant risk factors for developing diabetes were age, sex, obesity, fasting plasma glucose, hypertension, and hypercholesterolmia. A nomogram was constructed using these variables and internally validated. The area under the curve was 0.70 (95% confidence interval, .666-.730, P < .0001) and the calibration plot showed agreement between the actual and nomogram-predicted diabetes probabilities.The nomogram developed in this study is easy to use and convenient for identifying cancer patients at high-risk for type 2 diabetes, enabling early type 2 diabetes screening and management.

Diabetes After Hormone Therapy in Breast Cancer Survivors: A Case-Cohort Study

Purpose Breast cancer treatments have been associated with an increased risk of multiple health-related adverse outcomes, but the relationship with diabetes remains unclear. This study investigated the association between hormone therapy and diabetes risk in breast cancer survivors. Patients and Methods We performed a case-cohort study of 2,246 female survivors recruited from the Leumit health care fund who were diagnosed with primary nonmetastatic invasive breast cancer in 2002 through 2012. A 20% random subcohort was sampled at baseline, and all diabetes cases were identified. Adjusted hazard ratios (HRs) with 95% CIs were estimated by weighted Cox proportional hazards regression models. Results Of 2,246 breast cancer survivors, 324 developed diabetes over a mean follow-up of 5.9 years. The crude cumulative incidence of diabetes that accounted for death as a competing risk was 20.9% (95% CI, 18.3% to 23.7%). In multivariable-adjusted models, hormone therapy was associated with increased diabetes risk (HR, 2.40; 95% CI, 1.26 to 4.55; P = .008). The hazard for tamoxifen use (HR, 2.25; 95% CI, 1.19 to 4.26; P = .013) was less pronounced than the use of aromatase inhibitors (HR, 4.27, 95% CI, 1.42 to 12.84; P = .010). Conclusion Active hormone therapy is a significant risk factor of diabetes among breast cancer survivors. Although cessation of treatment is not recommended because the survival benefits of hormone therapy outweigh the risks, preventive strategies aimed at lifestyle modifications may minimize the risk.

Liraglutide inhibits the proliferation and promotes the apoptosis of MCF-7 human breast cancer cells through downregulation of microRNA-27a expression

The use of glucagon-like peptide-1 analogues, such as liraglutide, as hypoglycemic drugs has been widely employed in clinical practice. Liraglutide is reported to exert potential anti-breast cancer effects, however the specific mechanisms of this action remain unknown. In the present study, MCF-7 human breast cancer cells were cultured in vitro and treated with various concentrations of liraglutide. Cell Counting Kit-8, colony formation and flow cytometry assays were performed to determine the proliferation and apoptosis of cells following treatment. Furthermore, reverse transcription-quantitative polymerase chain reaction was employed to measure the expression level of microRNA (miRNA/miR)-27a. In addition, miR-27a mimics, inhibitors and negative controls were transfected into MCF-7 cells and the proliferation and apoptosis of cells following transfection was subsequently determined. Western blotting was performed to detect alterations in the protein expression of AMP-activated protein kinase catalytic subunit α2 (AMPKα2), proliferating cell nuclear antigen and cleaved-caspase-3 following treatments. The results demonstrated that, following treatment with liraglutide, the proliferation of MCF-7 cells was reduced and the apoptosis was increased, compared with the control group; this effect was increased with increasing concentrations of liraglutide. In addition, liraglutide treatment downregulated miR-27a expression in MCF-7 cells. While the overexpression of miR-27a promoted cell proliferation and inhibited apoptosis, knockdown of endogenous miR-27a inhibited cell proliferation and promoted apoptosis in MCF-7 cells. Furthermore, the expression of AMPKα2 protein in the group transfected with miR-27a mimics was decreased, while it was increased in MCF-7 cells transfected with miR-27a inhibitors. In conclusion, liraglutide may have a role in the inhibition of proliferation and promotion of apoptosis in MCF-7 cells. Concerning the mechanism of these effects, liraglutide may inhibit miR-27a expression, which subsequently increases the expression of AMPKα2 protein. The present study provides an experimental basis for the clinical treatment strategies of T2DM patients with breast cancer.

Mechanisms of Doxorubicin Toxicity in Pancreatic β-Cells

Exposure to chemotherapeutic agents has been linked to an increased risk of type 2 diabetes (T2D), a disease characterized by both the peripheral insulin resistance and impaired glucose-stimulated insulin secretion (GSIS) from pancreatic β-cells. Using the rat β-cell line INS-1 832/13 and isolated mouse pancreatic islets, we investigated the effect of the chemotherapeutic drug doxorubicin (Adriamycin) on pancreatic β-cell survival and function. Exposure of INS-1 832/13 cells to doxorubicin caused impairment of GSIS, cellular viability, an increase in cellular toxicity, as soon as 6 h post-exposure. Doxorubicin impaired plasma membrane electron transport (PMET), a pathway dependent on reduced equivalents NADH and NADPH, but failed to redox cycle in INS-1 832/13 cells and with their lysates. Although NADPH/NADP(+ )content was unaffected, NADH/NAD(+ )content decreased at 4 h post-exposure to doxorubicin, and was followed by a reduction in ATP content. Previous studies have demonstrated that doxorubicin functions as a topoisomerase II inhibitor via induction of DNA cross-linking, resulting in apoptosis. Doxorubicin induced the expression of mRNA for mdm2, cyclin G1, and fas whereas downregulating p53, and increased the melting temperature of genomic DNA, consistent with DNA damage and induction of apoptosis. Doxorubicin also induced caspase-3 and -7 activity in INS-1 832/13 cells and mouse islets; co-treatment with the pan-caspase inhibitor Z-VAD-FMK temporarily attenuated the doxorubicin-mediated loss of viability in INS-1 832/13 cells. Together, these data suggest that DNA damage, not H2O2 produced via redox cycling, is a major mechanism of doxorubicin toxicity in pancreatic β-cells.