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Journal of the National Cancer Institute

JNCI Journal of the National Cancer Institute - RSS feed of current issue
Background

Asparaginyl endopeptidase (AEP) has been implicated in human cancer development. However, the molecular mechanisms underlying AEP regulation, including the role of pro-AEP activation, remain elusive.

Methods

We investigated the regulation of AEP by TRAF6 and its effects on tumor progression and metastasis in cancer cell lines, murine models, and specimens from patients using biochemical analyses, confocal microscopy, immunoelectron microscopy, and migration-invasion assays. The sera of healthy donors and breast cancer patients were examined by enzyme-linked immunosorbent assay, and a tissue array of 314 breast cancer specimens was assessed for AEP and TRAF6 by immunohistochemistry. Furthermore, the effects of AEP inhibitors or monoclonal antibodies on pulmonary metastasis were evaluated in murine models. The statistical significance between groups was determined using two-tailed Student t tests.

Results

We demonstrate that TRAF6 ubiquitinates the proform of AEP through K63-linked polyubiquitin, reversible by USP17, and forms a complex with HSP90α to subsequently promote pro-AEP intracellular stability as well as secretion. Disrupting the interaction between pro-AEP and TRAF6 or inhibiting HSP90α reduced pro-AEP secretion and consequently reduced tumor metastasis. Higher circulating AEP levels were detected in the sera of breast cancer patients, and AEP inhibitors or neutralizing antibodies remarkably decreased tumor metastasis in murine models. Notably, TRAF6 and AEP were overexpressed in human breast neoplasms and correlated with poor prognosis. Patients with low AEP/TRAF6 expression survived for a mean of 111 months (95% confidence interval [CI] = 108 to 115 months), whereas those with high AEP/TRAF6 expression survived for a mean of only 61 months (95% CI = 42 to 79 months; P < .001).

Conclusions

Our study elucidates a novel mechanism of AEP regulation and an alternative oncogenic pathway for TRAF6 in breast cancer, which suggests that AEP and TRAF6 protein levels may have prognostic implications in breast cancer patients. Thus, AEP may serve as a biomarker as well as new therapeutic target.


Background

Prior studies suggest that elevated markers of bone turnover are prognostic for poor survival in castration-resistant prostate cancer (CRPC). The predictive role of these markers relative to bone-targeted therapy is unknown. We prospectively evaluated the prognostic and predictive value of bone biomarkers in sera from CRPC patients treated on a placebo-controlled phase III trial of docetaxel with or without the bone targeted endothelin-A receptor antagonist atrasentan (SWOG S0421).

Methods

Markers for bone resorption (N-telopeptide and pyridinoline) and formation (C-terminal collagen propeptide and bone alkaline phosphatase) were assayed in pretreatment and serial sera. Cox proportional hazards regression models were fit for overall survival. Models were fit with main effects for marker levels and with/without terms for marker–treatment interaction, adjusted for clinical variables, to assess the prognostic and predictive value of atrasentan. Analysis was adjusted for multiple comparisons. Two-sided P values were calculated using the Wald test.

Results

Sera from 778 patients were analyzed. Elevated baseline levels of each of the markers were associated with worse survival (P < .001). Increasing marker levels by week nine of therapy were also associated with subsequent poor survival (P < .001). Patients with the highest marker levels (upper 25th percentile for all markers) not only had a poor prognosis (hazard ratio [HR] = 4.3; 95% confidence interval [CI] = 2.41 to 7.65; P < .001) but also had a survival benefit from atrasentan (HR = 0.33; 95% CI = 0.15 to 0.71; median survival = 13 [atrasentan] vs 5 months [placebo]; P interaction = .005).

Conclusions

Serum bone metabolism markers have statistically significant independent prognostic value in CRPC. Importantly, a small group of patients (6%) with highly elevated markers of bone turnover appear to preferentially benefit from atrasentan therapy.




Background

Chronic inflammation plays a role in the development of colorectal cancer (CRC). The novel plasma inflammatory biomarker macrophage inhibitory cytokine-1 (MIC-1, GDF15) may have a direct mechanistic role in colorectal carcinogenesis.

Methods

We conducted a prospective, nested, case–control study of incident CRC among men and women who provided a prediagnostic blood specimen. We used an enzyme-linked immunosorbent assay to measure MIC-1 and examined associations between quintiles of MIC-1 and CRC using logistic regression adjusted for matching factors (age and date of blood draw), risk factors, and other plasma inflammatory markers. We also assessed the relationship between MIC-1 levels and prostaglandin-endoperoxide synthase 2 (PTGS2)/cyclooxygenase-2 (COX-2) enzyme status in tumors with available tissue for analysis. All statistical tests were two-sided.

Results

Compared with men and women within the lowest quintile of plasma MIC-1, the multivariable relative risk (RR) for CRC was 1.93 (95% confidence interval [CI] = 1.27 to 2.94) for the highest quintile (P linear trend = .004). In an exploratory analysis, we found that among individuals with high plasma MIC-1 levels (quintiles 2–5), compared with nonuse, regular use of aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs) was associated with a lower risk of PTGS2-positive CRC (multivariable RR = 0.60; 95% confidence interval = 0.41 to 0.88) but not PTGS2-negative CRC (multivariable RR = 1.21; 95% CI = 0.71 to 2.07). In contrast, among individuals with low MIC-1 levels (quintile 1), aspirin and NSAID use was not associated with a lower risk of PTGS2-positive CRC (multivariable RR = 0.57; 95% CI = 0.21 to 1.54) or PTGS2-negative CRC (multivariable RR = 1.41; 95% CI = 0.47 to 4.23).

Conclusions

Our results support an association between higher levels of circulating MIC-1 (GDF15) and CRC. Aspirin/NSAID use appeared to lower risk of PTGS2-positive cancers, particularly among individuals with high levels of circulating MIC-1.










The Ovarian Task Force of the Gynecologic Cancer Steering Committee convened a clinical trials planning meeting on October 28–29, 2011, with the goals to identify key tumor types, associated molecular pathways, and biomarkers for targeted drug intervention; review strategies to improve early-phase screening, therapeutic evaluation, and comparison of new agents; and optimize design of randomized trials in response to an evolving landscape of scientific, regulatory, and funding priorities. The meeting was attended by international clinical and translational investigators, pharmaceutical industry representatives, government regulators, and patient advocates. Panel discussions focused on disease types, early-phase trials, and randomized trials. A manuscript team summarized the discussions and assisted with formulating key recommendations. A more integrated and efficient approach for screening new agents using smaller selective randomized trials in specific disease-type settings was endorsed, together with collaborative funding models between industry and the evolving national clinical trials network, as well as efforts to enhance public awareness and study enrollment through advocacy.


Colorectal cancer (CRC) is a leading cause of cancer mortality worldwide. CRC incidence and mortality can be reduced through screening. However, in the United States, screening participation remains suboptimal, particularly among underserved populations such as the uninsured, recent immigrants, and racial/ethnic minority groups. Increasing screening rates among underserved populations will reduce the US burden of CRC. In this commentary focusing on underserved populations, we highlight the public health impact of CRC screening, list key challenges to screening the underserved, and review promising approaches to boost screening rates. We identify four key policy and research priorities to increase screening among underserved populations: 1) actively promote the message, "the best test is the one that gets done"; 2) develop and implement methods to identify unscreened individuals within underserved population groups for screening interventions; 3) develop and implement approaches for organized screening delivery; and 4) fund and enhance programs and policies that provide access to screening, diagnostic follow-up, and CRC treatment for underserved populations. This commentary represents the consensus of a diverse group of experts in cancer control and prevention, epidemiology, gastroenterology, and primary care from across the country who formed the Coalition to Boost Screening among the Underserved in the United States. The group was organized and held its first annual working group meeting in conjunction with the World Endoscopy Organization’s annual Colorectal Cancer Screening Committee meeting during Digestive Disease Week 2012 in San Diego, California.


Background

Prostate cancer is incurable once it has metastasized to the bone. Appropriate preclinical models are lacking. The therapeutic efficacy of the multikinase inhibitor cabozantinib was assessed in an orthotopic xenograft model of castration-resistant prostate cancer (CRPC) bone metastasis using noninvasive, multimodality functional imaging.

Methods

NOD/SCID mice were injected intratibially with luciferase-expressing ERG (v-ets avian erythroblastosis virus E26 oncogene homolog) rearranged VCaP human prostate carcinoma cells. The response of VCaP xenografts (n = 7 per group) to cabozantinib was investigated using bioluminescence imaging and anatomical and diffusion weighted magnetic resonance imaging. This enabled quantitation of tumor volume and apparent diffusion coefficient (ADC). Bone uptake of technetium-methylene diphosphonate (99mTc-MDP) was assessed by single-photon emission computed tomography. Ex vivo micro computed tomography was used to quantify bone volume and correlated with appropriate histopathology. Statistical significance was determined using the two-sided Mann–Whitney test or Wilcoxon signed rank test.

Results

VCaP xenografts were predominantly osteosclerotic with some osteolytic activity. Fluorescent in situ hybridization analysis confirmed retention of ERG oncogene rearrangements. Cabozantinib induced a statistically significant 52% reduction in tumor luminance (P = .02) and stasis in tumor volume after 15 days of treatment. Tumor ADC statistically significantly increased with cabozantinib and was associated with extensive necrosis (after 10 days, mean tumor ADC ± SD = 556±43x10–6 mm2/s vs pretreatment ADC = 485±43x10–6 mm2/s; P = .02 ). Tumor-associated uptake of 99mTc-MDP was statistically significantly reduced after 3 days of treatment (P = .02), sustained over 15 days treatment, and associated with a statistically significant (P = .048) reduction in bone growth on the tibial cortex, yet a highly statistically significant (P = .001) increase in trabecular bone volume.

Conclusions

The intratibial VCaP model faithfully emulates clinical disease. Cabozantinib exerts potent effects on both tumor and tumor-induced bone matrix remodeling, and quantitation of ADC provides a clinically translatable imaging biomarker for early, sensitive assessment of treatment response in CRPC bone metastasis.


Evidence-based guidelines for long-term follow-up of early-stage breast cancer patients developed by oncology societies in the United States and Europe recommend that breast cancer survivors undergo regular evaluation with history and physical examination, as well as annual mammography. Routine blood tests, circulating tumor markers, and/or surveillance imaging studies beyond mammography are not recommended in the absence of concerning symptoms or physical examination findings because of lack of supportive clinical evidence. Despite these guidelines, studies have shown that 20% to 40% of oncologists assess serum tumor markers as part of routine monitoring of early-stage breast cancer patients. As part of efforts to both address the financial challenges confronting the health-care system and optimize patient outcomes, the American Society of Clinical Oncology’s Cost of Care Task Force identified adherence to breast cancer surveillance guidelines as an opportunity to improve care and reduce cost. However, these recommendations are based on trials done in an era of outdated technology and limited therapeutic options. It is possible that recent improvements in diagnostics and treatments could make earlier detection of recurrent disease important for improving both survival and quality of life outcomes. Research is necessary to further inform optimal breast cancer follow-up strategies, which could impact these recommendations. At this time, outside of well-conducted clinical trials, there is no role for ordering routine serial blood or imaging tests in monitoring for recurrence in early-stage breast cancer patients.


Background

Progressive telomere shortening with cell division is a hallmark of aging. Short telomeres are associated with increased cancer risk, but there are conflicting reports about telomere length and mortality in breast cancer survivors.

Methods

We measured peripheral blood leukocyte telomere length at two time points in women enrolled in a multiethnic, prospective cohort of stage I to stage IIIA breast cancer survivors diagnosed between 1995 and 1999 with a median follow-up of 11.2 years. We evaluated associations between telomere length measured at mean 6 (baseline; LTL0; n = 611) and 30 months (LTL30; n = 478) after diagnosis and the change between those time points (n = 478), with breast cancer–specific and all-cause mortality using Cox proportional hazards models adjusted for possible confounders. Statistical tests were two-sided.

Results

There were 135 deaths, of which 74 were due to breast cancer. Neither baseline nor 30-month telomere length was associated with either all-cause or breast cancer–specific mortality (LTL0: hazard ratio [HR] = 0.83, 95% confidence interval [CI] = 0.67 to 1.02; HR = 0.88; 95% CI = 0.67 to 1.15; LTL30: HR = 0.78, 95% CI = 0.59 to 1.05; HR = 0.86; 95% = CI = 0.58 to 1.26, respectively). However, participants whose telomeres shortened between baseline and 30 months were at a statistically significantly increased risk of breast cancer–specific (HR = 3.03; 95% CI = 1.11 to 8.18) and all-cause mortality (HR = 2.38; 95% CI = 1.28 to 4.39) compared with participants whose telomeres lengthened. When follow-up was censored at 5-years after diagnosis, LTL0 (HR = 0.66; 95% CI = 0.45 to 0.96), LTL30 (HR = 0.51; 95% CI = 0.29 to 0.92), and change in telomere length (HR = 3.45; 95% CI = 1.11 to 10.75) were statistically significantly associated with all-cause mortality.

Conclusions

Telomere shortening was associated with increased risk of breast cancer–specific and all-cause mortality, suggesting that change in blood telomere length over time could be a biomarker of prognosis. Research on determinants of telomere length and change is needed.


Background

Previous studies have hypothesized that tumor blood flow may be elevated or reduced during exercise, which could impact the tumor microenvironment. However, to date technical limitations have precluded the measurement of tumor blood flow during exercise. Using an orthotopic preclinical model of prostate cancer, we tested the hypotheses that during exercise tumors would experience 1) diminished vascular resistance, 2) augmented blood flow, 3) increased numbers of perfused vessels, and 4) decreased tissue hypoxia and, furthermore, that the increased perfusion would be associated with diminished vasoconstriction in prostate tumor arterioles.

Methods

Dunning R-3327 MatLyLu tumor cells were injected into the ventral prostate of male Copenhagen rats aged 4 to 6 months randomly assigned to tumor-bearing (n = 42) or vehicle control (n = 14) groups. Prostate tumor blood flow, vascular resistance, patent vessel number, and hypoxia were measured in vivo in conscious rats at rest and during treadmill exercise, and vasoconstrictor responsiveness of resistance arterioles was investigated in vitro.

Results

During exercise there was a statistically significant increase in tumor blood flow (approximately 200%) and number of patent vessels (rest mean ± standard deviation [SD] = 12.7±1.3; exercise mean ± SD = 14.3±0.6 vessels/field; Student t test two-sided P = .02) and decreased hypoxia compared with measurements made at rest. In tumor arterioles, the maximal constriction elicited by norepinephrine was blunted by approximately 95% vs control prostate vessels.

Conclusions

During exercise there is enhanced tumor perfusion and diminished tumor hypoxia due, in part, to a diminished vasoconstriction. The clinical relevance of these findings are that exercise may enhance the delivery of tumor-targeting drugs as well as attenuate the hypoxic microenvironment within a tumor and lead to a less aggressive phenotype.


Background

The Net Reclassification Index (NRI) and its P value are used to make conclusions about improvements in prediction performance gained by adding a set of biomarkers to an existing risk prediction model. Although proposed only 5 years ago, the NRI has gained enormous traction in the risk prediction literature. Concerns have recently been raised about the statistical validity of the NRI.

Methods

Using a population dataset of 10000 individuals with an event rate of 10.2%, in which four biomarkers have no predictive ability, we repeatedly simulated studies and calculated the chance that the NRI statistic provides a positive statistically significant result. Subjects for training data (n = 420) and test data (n = 420 or 840) were randomly selected from the population, and corresponding NRI statistics and P values were calculated. For comparison, the change in the area under the receiver operating characteristic curve and likelihood ratio statistics were calculated.

Results

We found that rates of false-positive conclusions based on the NRI statistic were unacceptably high, being 63.0% in the training datasets and 18.8% to 34.4% in the test datasets. False-positive conclusions were rare when using the change in the area under the curve and occurred at the expected rate of approximately 5.0% with the likelihood ratio statistic.

Conclusions

Conclusions about biomarker performance that are based primarily on a statistically significant NRI statistic should be treated with skepticism. Use of NRI P values in scientific reporting should be halted.



Background

The c-Myc oncoprotein is activated in the majority of colorectal cancers (CRCs), whereas the TGF-β pathway is frequently affected by loss-of-function mutations, for example in SMAD2/3/4 genes. The canonical model places Myc downstream of inhibitory TGF-β signaling. However, we previously demonstrated that Myc also inhibits TGF-β signaling through the miR-17~92 microRNA cluster, raising the question about functional relationships between these two pathways.

Methods

We engineered a series of genetically complex murine and human CRC cell lines in which Myc and TGF-β activities could be manipulated simultaneously. This was achieved through retroviral expression of the Myc–estrogen receptor fusion protein and through Smad4 short hairpin RNA knockdown. Cell lines thus modified were injected subcutaneously in immunocompromised mice, and the resultant tumors (n = 5–10 per treatment group) were analyzed for overall growth and neovascularization. Additionally, the distribution of MYC and TGF-β pathway mutations was analyzed in previously profiled human CRC samples.

Results

In kras-mutated/trp53-deleted murine colonocytes, either Myc activation or TGF-β inactivation increased tumor sizes and microvascular densities approximately 1.5- to 2.5-fold, chiefly through downregulation of thrombospondin-1 and related type I repeat–containing proteins. Combining Myc activation with TGF-β inactivation did not further accelerate tumorigenesis. This redundancy and the negative effect of TGF-β signaling on angiogenesis were also demonstrated using xenografts of human CRC cell lines. Furthermore, the analysis of the Cancer Genome Atlas data revealed that in CRC without microsatellite instability, overexpression of Myc and inactivation of Smads (including acquired mutations in SMAD2) are mutually exclusive, with odds ratio less than 0.1.

Conclusions

In human CRC, gain-of-function alterations in Myc and loss-of-function alterations in TGF-β exhibit a masking epistatic interaction and are functionally redundant.




TP53 is the most frequently mutated gene in human malignancies; however, de novo somatic mutations in childhood embryonal cancers such as neuroblastoma are rare. We report on the analysis of three independent case–control cohorts comprising 10290 individuals and demonstrate that rs78378222 and rs35850753, rare germline variants in linkage disequilibrium that map to the 3' untranslated region (UTR) of TP53 and 5' UTR of the 133 isoform of TP53, respectively, are robustly associated with neuroblastoma (rs35850753: odds ratio [OR] = 2.7, 95% confidence interval [CI] = 2.0 to 3.6, P combined = 3.43x10–12; rs78378222: OR = 2.3, 95% CI = 1.8 to 2.9, P combined = 2.03x10–11). All statistical tests were two-sided. These findings add neuroblastoma to the complex repertoire of human cancers influenced by the rs78378222 hypomorphic allele, which impairs proper termination and polyadenylation of TP53 transcripts. Future studies using whole-genome sequencing data are likely to reveal additional rare variants with large effect sizes contributing to neuroblastoma tumorigenesis.


Background

Inclusion in trials is selective, and thus results may not be generalizable to the general population. The aim of this study was to investigate the external validity of randomized clinical trial outcomes for elderly breast cancer patients.

Methods

We compared characteristics and outcomes of breast cancer patients (n = 1325) who participated in a randomized clinical trial (Tamoxifen Exemestane Adjuvant Multinational trial) with unselected breast cancer patients of corresponding age from the general population (n = 1056). Dutch patients aged 65 years or older at diagnosis of hormone receptor–positive breast cancer without distant metastases, with either nodal involvement, a tumor greater than 3cm, or a 1 to 3cm histological grade III tumor, who completed local therapy were included. Analyses were stratified by age (65–74 years; ≥75 years). Primary outcome was overall mortality. Multivariable Cox proportional hazards models were used to assess the association between covariables and overall mortality. All statistical tests were two-sided.

Results

Irrespective of age, patients who participated in the trial had fewer comorbid diseases, a higher socioeconomic status, and smaller tumors (all P < .001). In patients aged 65 to 74 years, those who participated in the trial had a similar overall mortality to patients from the general population (multivariable hazard ratio [HR] = 1.08; 95% confidence interval [CI] = 0.73 to 1.60). Alternatively, in patients aged 75 years or older, those who participated in the trial had a lower overall mortality (multivariable HR = 0.72; 95% CI = 0.55 to 0.95; P = .02) than patients in the general population.

Conclusions

Breast cancer trial participants aged 75 years or older do not represent elderly breast cancer patients of corresponding age from the general population, which hampers the external validity of a trial.


Background

The nuclear receptor peroxisome proliferator-activated receptor-/β (PPAR-d) is upregulated in human colorectal cancers, but its role in colonic tumorigenesis remains controversial.

Methods

We generated a novel mouse model of intestinally targeted PPAR-d overexpression to simulate PPAR-d upregulation in human colon carcinogenesis. Colon-specific PPAR-d overexpression was confirmed by real-time reverse transcription polymerase chain reaction, immunoblotting, and activity assays. Mice with and without targeted PPAR-d overexpression were tested for azoxymethane (AOM)–induced colonic tumorigenesis. Mouse whole-genome transcriptome microarray analyses were performed to identify PPAR-d target genes to promote tumorigenesis. We used linear models to test for PPAR-d overexpression trend effects on tumor multiplicity. All statistical tests were two-sided.

Results

Targeted PPAR-d overexpression markedly increased colonic tumor incidence (from 0 of 10 wild-type [WT] littermate mice to 9 of 10 mice [P < .001] in 2 FVB/N background mouse lines [villin-PPAR-d-1 and villin-PPAR-d-2] at a 5-mg/kg AOM dose) and multiplicity (number of tumors per mouse per mg/kg dose of AOM increased from 0.47 [95% confidence interval [CI] = 0.22 to 0.72] for the WT littermates to 2.15 [95% CI = 1.90 to 2.40] [P < .001] for the villin-PPAR-d-1 mice and from 0.44 [95% CI = 0.09 to 0.79] for the WT littermates to 1.91 [95% CI = 1.57 to 2.25] [P < .001] for the villin-PPAR-d-2 mice). PPAR-d overexpression reversed resistance to AOM-induced colonic tumorigenesis in C57BL/6 mice. PPAR-d overexpression modulated expression of several novel PPAR-d target genes in normal-appearing colonic epithelial cells of mice with PPAR-d overexpression in a pattern that matched the changes in colonic tumors.

Conclusions

Our finding that PPAR-d upregulation profoundly enhances susceptibility to colonic tumorigenesis should impact the development of strategies of molecularly targeting PPAR-d in cancer and noncancerous diseases.


Background

p53 influences genomic stability, apoptosis, autophagy, response to stress, and DNA damage. New p53-target genes could elucidate mechanisms through which p53 controls cell integrity and response to damage.

Methods

DRAGO (drug-activated gene overexpressed, KIAA0247) was characterized by bioinformatics methods as well as by real-time polymerase chain reaction, chromatin immunoprecipitation and luciferase assays, time-lapse microscopy, and cell viability assays. Transgenic mice (94 p53–/– and 107 p53+/– mice on a C57BL/6J background) were used to assess DRAGO activity in vivo. Survival analyses were performed using Kaplan–Meier curves and the Mantel–Haenszel test. All statistical tests were two-sided.

Results

We identified DRAGO as a new p53-responsive gene induced upon treatment with DNA-damaging agents. DRAGO is highly conserved, and its ectopic overexpression resulted in growth suppression and cell death. DRAGO–/– mice are viable without macroscopic alterations. However, in p53–/– or p53+/– mice, the deletion of both DRAGO alleles statistically significantly accelerated tumor development and shortened lifespan compared with p53–/– or p53+/– mice bearing wild-type DRAGO alleles (p53–/–, DRAGO–/– mice: hazard ratio [HR] = 3.25, 95% confidence interval [CI] = 1.7 to 6.1, P < .001; p53+/–, DRAGO–/– mice: HR = 2.35, 95% CI = 1.3 to 4.0, P < .001; both groups compared with DRAGO+/+ counterparts). DRAGO mRNA levels were statistically significantly reduced in advanced-stage, compared with early-stage, ovarian tumors, but no mutations were found in several human tumors. We show that DRAGO expression is regulated both at transcriptional—through p53 (and p73) and methylation-dependent control—and post-transcriptional levels by miRNAs.

Conclusions

DRAGO represents a new p53-dependent gene highly regulated in human cells and whose expression cooperates with p53 in tumor suppressor functions.


Background

Senescent cells, which express p16 INK4a , accumulate with aging and contribute to age-related pathology. To understand whether cytotoxic agents promote molecular aging, we measured expression of p16 INK4a and other senescence markers in breast cancer patients treated with adjuvant chemotherapy.

Methods

Blood and clinical information were prospectively obtained from 33 women with stage I to III breast cancer at four time points: before anthracycline-based chemotherapy, immediately after anthracycline-based chemotherapy, 3 months after anthracycline-based chemotherapy, and 12 months after anthracycline-based chemotherapy. Expression of senescence markers p16 INK4a and ARF mRNA was determined using TaqMan quantitative reverse-transcription polymerase chain reaction in CD3+ T lymphocytes, telomere length was determined by Southern analysis, and senescence-associated cytokines were determined by enzyme-linked immunosorbent assay. Findings were independently assessed in a cross-sectional cohort of 176 breast cancer survivors enrolled a median of 3.4 years after treatment; 39% previously received chemotherapy. All statistical tests were two-sided.

Results

In prospectively analyzed patients, expression of p16 INK4a and ARF increased immediately after chemotherapy and remained elevated 12 months after treatment. Median increase in log2 p16 INK4a was 0.81 (interquartile range = 0.28–1.62; Wilcoxon signed-rank P < .001), or a 75% absolute increase in expression, equivalent to the increase observed over 14.7 years of chronological aging. ARF expression was comparably increased (P < .001). Increased expression of p16 INK4a and ARF was associated with dose-dense therapy and hematological toxicity. Expression of two senescence-associated cytokines (VEGFA and MCP1) was durably increased by adjuvant chemotherapy. Telomere length was not affected by chemotherapy. In a cross-sectional cohort, prior chemotherapy exposure was independently associated with a log2-increase in p16 INK4a expression of 0.57 (repeated measures model, P < .001), comparable with 10.4 years of chronological aging.

Conclusions

Adjuvant chemotherapy for breast cancer is gerontogenic, inducing cellular senescence in vivo, thereby accelerating molecular aging of hematopoietic tissues.




Background

Genome-wide association studies have identified hundreds of genetic variants associated with specific cancers. A few of these risk regions have been associated with more than one cancer site; however, a systematic evaluation of the associations between risk variants for other cancers and lung cancer risk has yet to be performed.

Methods

We included 18023 patients with lung cancer and 60543 control subjects from two consortia, Population Architecture using Genomics and Epidemiology (PAGE) and Transdisciplinary Research in Cancer of the Lung (TRICL). We examined 165 single-nucleotide polymorphisms (SNPs) that were previously associated with at least one of 16 non–lung cancer sites. Study-specific logistic regression results underwent meta-analysis, and associations were also examined by race/ethnicity, histological cell type, sex, and smoking status. A Bonferroni-corrected P value of 2.5x10–5 was used to assign statistical significance.

Results

The breast cancer SNP LSP1 rs3817198 was associated with an increased risk of lung cancer (odds ratio [OR] = 1.10; 95% confidence interval [CI] = 1.05 to 1.14; P = 2.8x10–6). This association was strongest for women with adenocarcinoma (P = 1.2x10–4) and not statistically significant in men (P = .14) with this cell type (P het by sex = .10). Two glioma risk variants, TERT rs2853676 and CDKN2BAS1 rs4977756, which are located in regions previously associated with lung cancer, were associated with increased risk of adenocarcinoma (OR = 1.16; 95% CI = 1.10 to 1.22; P = 1.1x10–8) and squamous cell carcinoma (OR = 1.13; CI = 1.07 to 1.19; P = 2.5x10–5), respectively.

Conclusions

Our findings demonstrate a novel pleiotropic association between the breast cancer LSP1 risk region marked by variant rs3817198 and lung cancer risk.