The role of area-level socioeconomic disadvantage in racial disparities in cancer incidence in metropolitan Detroit.

BACKGROUND: Neighborhood deprivation is associated with both race and cancer incidence, but there is a need to better understand the effect of structural inequities on racial cancer disparities. The goal of this analysis was to evaluate the relationship between a comprehensive measure of neighborhood-level social disadvantage and cancer incidence within the racially diverse population of metropolitan Detroit. METHODS: We estimated breast, colorectal, lung, and prostate cancer incidence rates using Metropolitan Detroit Cancer Surveillance System and US decennial census data. Neighborhood socioeconomic disadvantage was measured by the Area Deprivation Index (ADI) using Census Bureau's American Community Survey data at the Public Use Microdata Areas (PUMA) level. Associations between ADI at time of diagnosis and cancer incidence were estimated using Poisson mixed-effects models adjusting for age and sex. Attenuation of race-incidence associations by ADI was quantified using the "mediation" package in R. RESULTS: ADI was inversely associated with incidence of breast cancer for both non-Hispanic White (NHW) and non-Hispanic Black (NHB) women (NHW: per-quartile RR = 0.92, 95% CI 0.88-0.96; NHB: per-quartile RR = 0.94, 95% CI 0.91-0.98) and with prostate cancer incidence only for NHW men (per-quartile RR = 0.94, 95% CI 0.90-0.97). ADI was positively associated with incidence of lung cancer for NHWs and NHBs (NHW: per-quartile RR = 1.12, 95% CI 1.04-1.21; NHB: per-quartile RR = 1.37, 95% CI 1.25-1.51) and incidence of colorectal cancer (CRC) only among NHBs (per-quartile RR = 1.11, 95% CI 1.02-1.21). ADI significantly attenuated the relationship between race and hormone receptor positive, HER2-negative breast cancer (proportion attenuated = 8.5%, 95% CI 4.1-16.6%) and CRC cancer (proportion attenuated = 7.3%, 95% CI 3.7 to 12.8%), and there was a significant interaction between race and ADI for lung (interaction RR = 1.22, p < 0.0001) and prostate cancer (interaction RR = 1.09, p = 0.00092). CONCLUSIONS: Area-level socioeconomic disadvantage is associated with risk of common cancers in a racially diverse population and plays a role in racial differences in cancer incidence.

Area-level Socioeconomic Disadvantage and Cancer Survival in Metropolitan Detroit.

BACKGROUND: Racial segregation is linked to poorer neighborhood quality and adverse health conditions among minorities, including worse cancer outcomes. We evaluated relationships between race, neighborhood social disadvantage, and cancer survival. METHODS: We calculated overall and cancer-specific survival for 11,367 non-Hispanic Black (NHB) and 29,481 non-Hispanic White (NHW) individuals with breast, colorectal, lung, or prostate cancer using data from the Metropolitan Detroit Cancer Surveillance System. The area deprivation index (ADI) was used to measure social disadvantage at the census block group level, where higher ADI is associated with poorer neighborhood factors. Associations between ADI and survival were estimated using Cox proportional hazards mixed-effects models accounting for geographic grouping and adjusting for demographic and clinical factors. RESULTS: Increasing ADI quintile was associated with increased overall mortality for all four cancer sites in multivariable-adjusted models. Stratified by race, these associations remained among breast (NHW: HR = 1.16, P < 0.0001; NHB: HR = 1.20, P < 0.0001), colorectal (NHW: HR = 1.11, P < 0.0001; NHB: HR = 1.09, P = 0.00378), prostate (NHW: HR = 1.18, P < 0.0001; NHB: HR = 1.18, P < 0.0001), and lung cancers (NHW: HR = 1.06, P < 0.0001; NHB: HR = 1.07, P = 0.00177). Cancer-specific mortality estimates were similar to overall mortality. Adjustment for ADI substantially attenuated the effects of race on mortality for breast [overall proportion attenuated (OPA) = 47%, P < 0.0001; cancer-specific proportion attenuated (CSPA) = 37%, P < 0.0001] prostate cancer (OPA = 51%, P < 0.0001; CSPA = 56%, P < 0.0001), and colorectal cancer (OPA = 69%, P = 0.032; CSPA = 36%, P = 0.018). CONCLUSIONS: Area-level socioeconomic disadvantage is related to cancer mortality in a racially diverse population, impacting racial differences in cancer mortality. IMPACT: Understanding the role of neighborhood quality in cancer survivorship could improve community-based intervention practices.

ATR inhibition overcomes platinum tolerance associated with ERCC1- and p53-deficiency by inducing replication catastrophe.

ERCC1/XPF is a heterodimeric DNA endonuclease critical for repair of certain chemotherapeutic agents. We recently identified that ERCC1- and p53-deficient lung cancer cells are tolerant to platinum-based chemotherapy. ATR inhibition synergistically re-stored platinum sensitivity to platinum tolerant ERCC1-deficient cells. Mechanistically we show this effect is reliant upon several functions of ATR including replication fork protection and altered cell cycle checkpoints. Utilizing an inhibitor of replication protein A (RPA), we further demonstrate that replication fork protection and RPA availability are critical for platinum-based drug tolerance. Dual treatment led to increased formation of DNA double strand breaks and was associated with chromosome pulverization. Combination treatment was also associated with increased micronuclei formation which were capable of being bound by the innate immunomodulatory factor, cGAS, suggesting that combination platinum and ATR inhibition may also enhance response to immunotherapy in ERCC1-deficient tumors. In vivo studies demonstrate a significant effect on tumor growth delay with combination therapy compared with single agent treatment. Results of this study have led to the identification of a feasible therapeutic strategy combining ATR inhibition with platinum and potentially immune checkpoint blockade inhibitors to overcome platinum tolerance in ERCC1-deficient, p53-mutant lung cancers.

Mitochondrial isolation from skeletal muscle.

Mitochondria are organelles controlling the life and death of the cell. They participate in key metabolic reactions, synthesize most of the ATP, and regulate a number of signaling cascades. Past and current researchers have isolated mitochondria from rat and mice tissues such as liver, brain and heart. In recent years, many researchers have focused on studying mitochondrial function from skeletal muscles. Here, we describe a method that we have used successfully for the isolation of mitochondria from skeletal muscles. Our procedure requires that all buffers and reagents are made fresh and need about 250-500 mg of skeletal muscle. We studied mitochondria isolated from rat and mouse gastrocnemius and diaphragm, and rat extraocular muscles. Mitochondrial protein concentration is measured with the Bradford assay. It is important that mitochondrial samples be kept ice-cold during preparation and that functional studies be performed within a relatively short time (~1 hr). Mitochondrial respiration is measured using polarography with a Clark-type electrode (Oxygraph system) at 37°C7. Calibration of the oxygen electrode is a key step in this protocol and it must be performed daily. Isolated mitochondria (150 µg) are added to 0.5 ml of experimental buffer (EB). State 2 respiration starts with addition of glutamate (5 mM) and malate (2.5 mM). Then, adenosine diphosphate (ADP) (150 µM) is added to start state 3. Oligomycin (1 µM), an ATPase synthase blocker, is used to estimate state. Lastly, carbonyl cyanide p-[trifluoromethoxy]-phenyl-hydrazone (FCCP, 0.2 µM) is added to measurestate, or uncoupled respiration. The respiratory control ratio (RCR), the ratio of state 3 to state 4, is calculated after each experiment. An RCR ≥ 4 is considered as evidence of a viable mitochondria preparation. In summary, we present a method for the isolation of viable mitochondria from skeletal muscles that can be used in biochemical (e.g., enzyme activity, immunodetection, proteomics) and functional studies (mitochondrial respiration).