A health-system-embedded deprescribing intervention targeting patients and providers to prevent falls in older adults (STOP-FALLS trial): study protocol for a pragmatic cluster-randomized controlled trial.

BACKGROUND: Central nervous system (CNS) active medications have been consistently linked to falls in older people. However, few randomized trials have evaluated whether CNS-active medication reduction reduces falls and fall-related injuries. The objective of the Reducing CNS-active Medications to Prevent Falls and Injuries in Older Adults (STOP-FALLS) trial is to test the effectiveness of a health-system-embedded deprescribing intervention focused on CNS-active medications on the incidence of medically treated falls among community-dwelling older adults. METHODS: We will conduct a pragmatic, cluster-randomized, parallel-group, controlled clinical trial within Kaiser Permanente Washington to test the effectiveness of a 12-month deprescribing intervention consisting of (1) an educational brochure and self-care handouts mailed to older adults prescribed one or more CNS-active medications (aged 60 + : opioids, benzodiazepines and Z-drugs; aged 65 + : skeletal muscle relaxants, tricyclic antidepressants, and antihistamines) and (2) decision support for their primary health care providers. Outcomes are examined over 18-26 months post-intervention. The primary outcome is first incident (post-baseline) medically treated fall as determined from health plan data. Our sample size calculations ensure at least 80% power to detect a 20% reduction in the rate of medically treated falls for participants receiving care within the intervention (n = 9) versus usual care clinics (n = 9) assuming 18 months of follow-up. Secondary outcomes include medication discontinuation or dose reduction of any target medications. Safety outcomes include serious adverse drug withdrawal events, unintentional overdose, and death. We will also examine medication signetur fields for attempts to decrease medications. We will report factors affecting implementation of the intervention. DISCUSSION: The STOP-FALLS trial will provide new information about whether a health-system-embedded deprescribing intervention that targets older participants and their primary care providers reduces medically treated falls and CNS-active medication use. Insights into factors affecting implementation will inform future research and healthcare organizations that may be interested in replicating the intervention. TRIAL REGISTRATION: ClinicalTrial.gov NCT05689554. Registered on 18 January 2023, retrospectively registered.

STRategies to Improve Pain and Enjoy life (STRIPE): Protocol for a pragmatic randomized trial of pain coping skills training and opioid medication taper guidance for patients on long-term opioid therapy.

High-dose, long-term opioid therapy (LtOT) is associated with risk for serious harms. Rapid opioid discontinuation may lead to increased pain, psychological distress, and illicit opioid use, but gradual, supported opioid taper may reduce these risks. We previously demonstrated that an opioid taper support and pain coping skills training intervention reduced opioid dose more than usual care (43% vs 19% dose reduction from baseline), with no increase in pain intensity and a significant reduction in activity interference. We aim to adapt and test this intervention in the Kaiser Permanente Washington healthcare system with STRategies to Improve Pain and Enjoy life (STRIPE, NCT03743402), a pragmatic, randomized trial. Our goal was to randomize 215 participants on moderate-high dose (≥40 morphine milligram equivalent/day) LtOT to either cognitive-behavioral therapy-based pain coping skills training involving 18 telephone sessions over 52 weeks with optional opioid taper support or usual care. Data are collected from electronic health records, claims, and self-report. The primary outcomes are mean daily opioid dose and the pain intensity, interference with enjoyment of life, and interference with general activity (PEG) score at 12 months (primary time point) and 6 months (secondary time point). Secondary outcomes include having ≥30% opioid dose reduction from baseline, and patient-reported problem opioid use, opioid-related difficulties, pain self-efficacy, opioid craving, global impression of change, and anxiety and depressive symptoms at 6 and 12 months. If effective, this treatment could reduce opioid exposure and associated risks to patients, families, and communities while offering patients an alternative for managing pain.

Changes in use of opioid therapy after colon cancer diagnosis: a population-based study.

PURPOSE: To describe patterns of opioid use in cancer survivors. METHODS: In a cohort study of colon cancer patients diagnosed during 1995-2014 and enrolled at two Kaiser Permanente regions, we constructed quarterly measures of opioid use from 1 year before cancer diagnosis through 5 years after diagnosis to examine changes in use. Measures included any use, incident use, regular use (use ≥ 45 days in a 91-day quarter), and average daily dose (converted to morphine milligram equivalent, MME). We also assessed temporal trends of opioid use. RESULTS: Of 2,039 colon cancer patients, 11-15% received opioids in the four pre-diagnosis quarters, 68% in the first quarter after diagnosis, and 15-17% in each subsequent 19 quarters. Regular opioid use increased from 3 to 5% pre-diagnosis to 5-7% post diagnosis. Average dose increased from 15 to 17 MME/day pre-diagnosis to 14-22 MME/day post diagnosis (excluding the quarter in which cancer was diagnosed). Among post-diagnosis opioid users, 73-95% were on a low dose (< 20 MME/day). Over years, regular use of opioids increased in survivorship with no change in dosage. CONCLUSION: Opioid use slightly increased following a colon cancer diagnosis, but high-dose use was rare. Research is needed to differentiate under- versus over-treatment of cancer pain.

Symptom Burden in Long-Term Survivors of Head and Neck Cancer: Patient-Reported Versus Clinical Data.

INTRODUCTION: The symptom burden faced by long-term head and neck cancer survivors is not well understood. In addition, the accuracy of clinical data sources for symptom ascertainment is not clear. OBJECTIVE: To 1) describe the prevalence of symptoms in 5-year survivors of head and neck cancer, and 2) to evaluate agreement between symptoms obtained via self-report and symptoms obtained from clinical data sources. METHODS: We recruited 5-year survivors of head and neck cancer enrolled at Kaiser Permanente Washington (n = 54). Symptoms were assessed using the MD Anderson Symptom Inventory head and neck cancer module. For each symptom, we assessed the agreement of the patient's survey response ("gold standard") with the 1) medical chart and 2) administrative health care claims data. We computed the sensitivity, specificity, positive predictive value (PPV), and negative predictive value, along with their 95 percent confidence intervals, for each clinical data source. RESULTS: Eighty percent of patients responded. Nearly all participants (95 percent) reported experiencing at least one symptom from the MDASI-HN, and 93 percent reported two or more symptoms. Among patients reporting a given symptom, there was generally no evidence of the symptom from either clinical data source (i.e., sensitivity was generally no greater than 40 percent). The specificity and PPV of the clinical data sources were generally higher than the sensitivity. CONCLUSION: Relying only on medical chart review and/or administrative health data would substantially underestimate symptom burden in long-term head and neck cancer survivors.

Cardiovascular medication use and risks of colon cancer recurrences and additional cancer events: a cohort study.

BACKGROUND: Cardiovascular medications may be associated with cancer development, but little is known about their association with cancer recurrence. Medications such as statins and antihypertensives may be commonly used among colon cancer survivors, who are, on average, diagnosed in their mid-60s. We described the associations between statins and antihypertensive medications and colon cancer recurrence in a large, population-based study. METHODS: We conducted a cohort study among adults with stage I-IIIA colon cancer diagnosed in 1995-2014 in two Kaiser Permanente regions, Colorado and Washington. Statin and antihypertensive use were obtained from electronic pharmacy dispensing data. People were classified as medication users on the date of their first dispensing after cohort entry, which started 90 days after completing cancer treatment, continuing through the earliest of death, health plan disenrollment, or chart abstraction. We collected outcome information from medical record abstraction and tumor registries on colon cancer recurrences and second primary cancers. Using Cox proportional hazards multivariable models, we estimated hazard ratios (HRs) with 95% confidence intervals (CIs) for colon cancer recurrences and any cancer event (recurrences and new primaries at any anatomic site) comparing medication users to non-users. RESULTS: Among 2039 people, 937 (46%) used statins and 1425 (70%) used antihypertensives at any point during a median of 4.9 years of follow-up; 460 people had any additional cancer event, including 152 with a colon cancer recurrence. Statin use was not associated with colon cancer recurrence (HR = 1.09, 95%CI = 0.65-1.85) or any cancer event (HR = 1.12, 95%CI = 0.85-1.47), nor was antihypertensive use associated with recurrence (HR = 0.73, 95%CI = 0.44-1.21) or any cancer event (HR = 0.93, 95%CI = 0.70-1.24). CONCLUSIONS: Our results suggest no association between cardiovascular medication use and the risk of recurrence or any additional cancer, and may provide reassurance to colon cancer survivors.

Use of antidepressants after colon cancer diagnosis and risk of recurrence.

OBJECTIVE: Prior research examining the association between use of antidepressants after colon cancer diagnosis and risk of recurrence is scant. We evaluated this association among colon cancer patients diagnosed at two integrated health care delivery systems in the United States. METHODS: We conducted a cohort study of stage I to IIIA colon cancer patients diagnosed at greater than or equal to 18 years of age at Kaiser Permanente Colorado and Kaiser Permanente Washington during 1995 to 2014. We used pharmacy records to identify dispensings for antidepressants and tumor registry records and patients' medical charts to identify cancer recurrences. Using Cox proportional hazards models, we estimated the adjusted hazard ratio (HR) of colon cancer recurrence comparing patients who used antidepressants after diagnosis to those who did not. We also evaluated the risk associated with use of selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs) separately. RESULTS: Among the 1923 eligible colon cancer patients, 807 (42%) used an antidepressant after diagnosis and 139 had a colon cancer recurrence during an average 5.6 years of follow-up. Use of antidepressants after colon cancer diagnosis was not associated with risk of recurrence (HR: 1.14; 95% confidence interval [CI], 0.69-1.87). The HR for use of SSRIs was 1.22 (95% CI, 0.64-2.30), and for TCAs, it was 1.18 (95% CI, 0.68-2.07). CONCLUSIONS: Our findings suggest that use of antidepressants after colon cancer diagnosis was common and not associated with risk of recurrence. Future larger studies with greater power to examine risk associated with individual antidepressants would be valuable additions to the evidence base.

Risk of colon cancer recurrence in relation to diabetes.

PURPOSE: To describe the association between diabetes and colon cancer recurrence. METHODS: We conducted a cohort study at two integrated health care delivery systems in the United States. Using tumor registry data, we identified patients aged ≥ 18 years when diagnosed with stage I-IIIA adenocarcinomas of the colon during 1995-2014. Pre-existing diabetes was ascertained via diagnosis codes. Medical records were reviewed for eligibility and to abstract recurrence and covariate information. Recurrence was ascertained beginning 90 days after the end of colon cancer treatment (i.e., cohort entry). Recurrence of any cancer or a new primary cancer at any site was a secondary outcome. We used multivariable Cox proportional hazards models to estimate hazard ratios (HR) and 95% confidence intervals (CIs) for the associations between diabetes at cohort entry and study outcomes. RESULTS: Among the 1,923 eligible patients, 393 (16.7%) had diabetes at cohort entry. Diabetes was not associated with recurrence (HR 0.87; 95% CI 0.56-1.33) or with any subsequent cancer (HR 1.09; 95% CI 0.85-1.40). When the definition of recurrence included second primary colorectal cancer, risk was non-significantly higher in patients with diabetes than without diabetes. CONCLUSIONS: The risk of colon cancer recurrence appears to be similar in patients with and without diabetes at diagnosis. IMPACT: Future studies should evaluate the association between diabetes and colorectal cancer outcomes, especially second primary colon cancers, in larger populations.

Financial difficulty, worry about affording care, and benefit finding in long-term survivors of cancer.

OBJECTIVE: To examine the associations of worry about affording care and reporting financial difficulties with benefit finding in long-term cancer survivors. METHODS: Long-term survivors of cancer (n = 547) in 3 integrated health care delivery systems completed the Medical Expenditure Panel Survey Cancer Survivorship Supplement. The relationship between benefit finding (becoming a stronger person, coping better, and making positive changes) and the potentially interacting factors of worry about affording care and financial difficulties was examined using multivariate logistic regression models. RESULTS: Of the total sample, 20% reported worry and 15% reported financial difficulty. Among those who reported no worry, financial difficulty was positively associated with becoming a stronger person (odds ratio [OR] = 2.89, 95% CI: 1.07, 7.80). Coping better was not associated with worry, financial difficulties, or the interaction of the two. Among those with no financial difficulty, worry was positively associated with making positive changes (OR = 2.64, 95% CI: 1.41, 4.96), and among those reporting no worry, financial difficulty had a non-significant positive association with making positive changes (OR = 1.98, 95% CI: 0.91, 4.31). Among those reporting worry, having financial difficulties was associated with lower odds of making positive changes (OR = 0.32, 95% CI: 0.13, 0.78). CONCLUSIONS: Our results suggest a complex relationship between financial difficulty, worry, and benefit finding. The combination of worry about affording care and financial difficulty needs to be addressed and further studied among cancer survivors, as the presence of both, but not alone, was negatively associated with making positive changes, an aspect of benefit finding.

Association of worry about cancer to benefit finding and functioning in long-term cancer survivors.

PURPOSE: Worry about cancer recurrence or progression is associated with negative effects of cancer, such as worse physical functioning, but associations with positive changes post-cancer, such as benefit finding, are unknown. We measured the proportion of patients reporting frequent worry about cancer recurrence or progression and examined the association between worry about cancer recurrence or progression to benefit finding and functioning in cancer. METHODS: We surveyed 594 long-term (5-10 years post-diagnosis) survivors of cancer (breast, prostate, colorectal, lung, melanoma) in this cross-sectional study. The survey asked about worry about cancer recurrence/progression, negative effects of cancer on mental and physical function, and benefit finding as a result of the cancer (positive effects). Multivariate regressions estimated associations of worry about cancer with negative and positive effects of cancer. RESULTS: Worrying about cancer often or all the time was reported by 19.6% of survivors. Worry about cancer was related to worse functioning (odds ratio (OR) range 1.40 to 1.46, all p's < .01). Worry about recurrence/progression was unrelated to benefit finding (all p's > .10). CONCLUSIONS: Worry about cancer was associated with negative, but not positive, effects of cancer. Treating worry about cancer is unlikely to reduce benefit finding after cancer. Given the high prevalence of worry about cancer and relationship to negative effects of cancer, clinical care should attempt to address this worry for long-term survivors.

Breast cancer recurrence in relation to antidepressant use.

PURPOSE: Women with breast cancer frequently use antidepressants; however, questions about the effect of these medications on breast cancer recurrence remain. METHODS: We identified 4,216 women ≥18 years with an incident stage I or II breast cancer diagnosed between 1990 and 2008 in a mixed-model healthcare delivery system linked to a cancer registry. Recurrences were ascertained from chart review. Medication exposures were extracted from electronic pharmacy records. We used multivariable Cox proportional hazards models to estimate hazard ratios (HR) and 95 % confidence intervals (CI) to assess the association between antidepressant use and breast cancer recurrence and mortality. We also conducted analyses restricted to tamoxifen users. RESULTS: Antidepressants overall, tricyclic antidepressants, and selective serotonin reuptake inhibitors were not associated with risk of breast cancer recurrence or mortality. Women taking paroxetine only (adjusted HR: 1.66; 95 % CI 1.02, 2.71) and trazodone only (adjusted HR: 1.76; 95 % CI 1.06, 2.92), but not fluoxetine only (adjusted HR: 0.92; 95 % CI 0.55, 1.53), had higher recurrence risks than antidepressant nonusers. There was some suggestion of an increased recurrence risk with concurrent paroxetine and tamoxifen use compared with users of tamoxifen only (adjusted HR: 1.49; 95 % CI 0.79, 2.83). CONCLUSIONS: In general, antidepressants did not appear increase risk of breast cancer recurrence, though there were some suggested increases in risk that warrant further investigation in other datasets. Our results combined systematically and quantitatively with results from other studies may be useful for patients and providers making decisions about antidepressant use after breast cancer diagnosis.

Psychometric investigation of benefit finding among long-term cancer survivors using the Medical Expenditure Panel Survey.

PURPOSE: Benefit finding has been shown to be beneficial for people with cancer and may be an indication that one is coping adequately with the stress of cancer. This study evaluated the psychometric properties of a four-item benefit finding measure from the cancer survivorship supplement of the Medical Expenditure Panel Survey (MEPS). METHODS: Long-term survivors (5-10 years post-diagnosis) of breast, prostate, colorectal or lung cancer or melanoma (n = 594) completed the MEPS cancer supplement survey in 2013. Four items asked about benefit finding after the cancer: stronger person, coping better, positive changes and having healthier habits. Information on sociodemographics, disease and activity limitations after the cancer was also collected. We examined factor structure, reliability (Kuder-Richardson 20) and validity. RESULTS: The four benefit finding items did not appear to measure one factor. Three of the benefit finding items (stronger person, coping better, positive changes) were related to gender, receipt of chemotherapy and activity limitations but not cancer stage, time since diagnosis or income. Having healthier habits was unrelated to any sociodemographic or disease variable. CONCLUSIONS: Three of the items (stronger person, coping better, positive changes) appeared to have validity as they were related to variables that literature has shown are related to benefit finding. However, having healthier habits is likely measuring a separate but related construct. This short instrument may be used in future studies assessing benefit finding post cancer; however, the four items should be analyzed separately.

Comparative safety of cardiovascular medication use and breast cancer outcomes among women with early stage breast cancer.

Breast cancer tends to occur in an older age group of women also burdened with comorbidities such as cardiovascular disease (CVD). Numerous medications used to manage CVD (e.g., statins and antihypertensives) are hypothesized to alter breast cancer risk, but there are few studies on breast cancer outcomes. The COmmonly used Medications and Breast Cancer Outcomes (COMBO) cohort was developed to study how medications and co-morbidities influence breast cancer prognosis. Cohort study among adult women, diagnosed with incident early stage breast cancer, and enrolled in an integrated health plan. Data sources included health plan administrative databases, Surveillance, Epidemiology, and End Results tumor registry, and medical records. Statins, angiotensin-converting enzyme inhibitors (ACEI), beta blockers (BB), calcium blockers, and diuretics were the exposures of interest. The outcome was second breast cancer events (SBCE) defined as recurrence or second primary breast cancer. We used multivariable Cox proportional hazards models to estimate hazard ratios (HR) and 95 % confidence intervals (CI) for SBCE, and components of SBCE. 4,216 women were followed for a median of 6.3 years, and 13.2 % experienced a SBCE (first of: n = 415 recurrences and n = 143 s primary breast cancers). Compared to non-users, we observed an increased risk of second primary breast cancer with ACEI use (HR = 1.66; 95 % CI, 1.06-2.58) and an increased risk of recurrence with BB use (HR = 1.29; 95 % CI, 1.01-1.64). There was suggestion of a reduced risk of SBCE with statin use (HR = 0.82; 95 % CI, 0.62-1.08) and second primary breast cancer with BB use (HR = 0.77; 95 % CI, 0.50-1.19). No differences in outcomes were observed by duration of medication use. A majority of CVD medications evaluated in this study appear safe with respect to SBCE, but ACEI and BB use warrant further evaluation. The study presented is one example of the questions that can be addressed using the COMBO cohort.

Frequent antibiotic use and second breast cancer events.

BACKGROUND: Antibiotic use may be associated with higher breast cancer risk and breast cancer mortality, but no study has evaluated the relation between antibiotic use and second breast cancer events (SBCE). METHODS: We conducted a retrospective cohort study among women ≥18 years, diagnosed with incident stage I/II breast cancer during 1990-2008. Antibiotic use and covariates were obtained from health plan administrative databases and medical record review. Frequent antibiotic use was defined as ≥4 antibiotic dispensings in any moving 12-month period after diagnosis. Our outcome was SBCE defined as recurrence or second primary breast cancer. We used multivariable Cox proportional hazards models to estimate HR and 95% confidence intervals (CI), accounting for competing risks. RESULTS: A total of 4,216 women were followed for a median of 6.7 years. Forty percent were frequent antibiotic users and 558 (13%) had an SBCE. Results are suggestive of a modest increased risk of SBCE (HR, 1.15; 95% CI, 0.88-1.50) among frequent antibiotic users compared with nonusers. Any potential increased risk was not supported when we evaluated recent use and past use. We observed no dose-response trends for SBCE with increasing duration of antibiotic use nor did we find evidence for altered SBCE risk in the antibiotic classes studied. CONCLUSIONS: Frequent antibiotic use may be associated with modestly elevated risk of SBCEs, but the association was not significant. IMPACT: Additional investigation by antibiotic class and underlying indication are important next steps given the high prevalence of frequent antibiotic use and growing number of breast cancer survivors.

Accuracy of ICD-9 codes to identify nonunion and malunion and developing algorithms to improve case-finding of nonunion and malunion.

OBJECTIVE: To evaluate the accuracy of using ICD-9 codes to identify nonunions (NU) and malunions (MU) among adults with a prior fracture code and to explore case-finding algorithms. STUDY DESIGN: Medical chart review of potential NU (N=300) and MU (N=288) cases. True NU cases had evidence of NU and no evidence of MU in the chart (and vice versa for MUs) or were confirmed by the study clinician. Positive predictive values (PPV) were calculated for ICD-9 codes. Case-finding algorithms were developed by a classification and regression tree analysis using additional automated data, and these algorithms were compared to true case status. SETTING: Group Health Cooperative. RESULTS: Compared to true cases as determined from chart review, the PPV of ICD-9 codes for NU and MU were 89% (95% CI, 85-92%) and 47% (95% CI, 41-53%), respectively. A higher proportion of true cases (NU: 95%; 95% CI, 90-98%; MU: 56%; 95% CI, 47-66%) were found among subjects with 1+ additional codes occurring in the 12months following the initial code. There was no case-finding algorithm for NU developed given the high PPV of ICD-9 codes. For MU, the best case-finding algorithm classified people as an MU case if they had a fracture in the forearm, hand, or skull and had no visit with an NU diagnosis code in the 12-month post MU diagnosis. PPV for this MU case-finding algorithm increased to 84%. CONCLUSIONS: Identifying NUs with its ICD-9 code is reasonable. Identifying MUs with automated data can be improved by using a case-finding algorithm that uses additional information. Further validation of the MU algorithms in different populations is needed, as well as exploration of its performance in a larger sample.

Patient-reported discontinuation of endocrine therapy and related adverse effects among women with early-stage breast cancer.

BACKGROUND: Approximately 20% to 50% of women diagnosed with hormone receptor-positive breast cancer discontinue endocrine therapy early; most reports come from automated pharmacy data or small self-report evaluations. We conducted a larger self-report evaluation of endocrine therapy discontinuation associated with patient characteristics and therapy-related adverse effects. METHODS: We surveyed 538 women from a single health plan who were diagnosed with early-stage breast cancer from 2002 to 2008 and received endocrine therapy. Women reported adverse effects and reasons for discontinuation via mailed survey; tumor characteristics were obtained via registry linkage. We classified women as discontinuers if they self-reported stopping therapy and their self-reported duration of tamoxifen plus aromatase inhibitor (AI) use was < 5 years, and nondiscontinuers if they self-reported ≥ 5 years use or current use. We estimated odds ratios (ORs) with 95% CIs for discontinuation versus continuation by using logistic regression adjusted for age and year of diagnosis. RESULTS: Among 538 women, 98 (18.2%) discontinued endocrine therapy early. Women with positive lymph nodes (v negative) were significantly less likely to discontinue therapy (odds ratio [OR] = 0.54; 95% CI, 0.31 to 0.93). Almost all women (94%) experienced adverse effects. Experiencing headaches was associated with discontinuation of AIs (OR = 4.16; 95% CI, 2.16 to 8.01) and tamoxifen (OR = 2.34; 95% CI, 1.24 to 4.41); few other individual adverse effects were related to discontinuation despite most discontinuers reporting they "did not like adverse effects" (AIs: 66.7%, tamoxifen: 59.1%). CONCLUSION: Few individual adverse effects or patient characteristics were significantly associated with endocrine therapy discontinuation, yet adverse effects were prevalent and were the most common reason women reported for discontinuing therapy.

Glad you asked: participants' opinions of re-consent for dbGap data submission.

No consensus exists about when researchers need additional participant consent (reconsent) to submit existing data to the federal database of Genotypes and Phenotypes (dbGaP). Re-consent for submission of their data to dbGaP was sought from 1,340 study participants, 1,159 (86%) of whom agreed. We invited the first 400 of those who agreed to complete a telephone survey about their reasoning for their consent decision and their satisfaction with the reconsent process; 365 participants completed the survey. Respondents reported that it was very (69%) or somewhat (21%) important that they were asked for their permission. Many respondents considered alternatives to consent, such as notification-only or opt-out, to be unacceptable (67% and 40%, respectively). These results suggest that re-consent for dbGaP deposition may be advisable in certain cases to anticipate and honor participant preferences.

E2A acts in cis in G1 phase of cell cycle to promote Ig gene diversification.

Rearranged Ig genes undergo diversification in sequence and structure initiated by the DNA deaminase, activation-induced deaminase. Ig genes must be transcribed for diversification to occur, but whether there are additional requirements for cis activation has not been established. Here we show, by chromatin immunoprecipitation, that the regulatory factor E2A associates with the rearranged Ig lambda(R) gene in the chicken DT40 B cell line, which performs constitutive Ig gene diversification. By analysis of a DT40 derivative in which polymerized lactose operator tags the rearranged lambda(R) gene, we show that E2A must function in cis to promote diversification and that stimulation of diversification in cis depends on the E2A activation domains. By direct imaging, we show that lambda(R)/E2A colocalizations are most prominent in G(1). We further show that expression of the E2A antagonist Id1 prevents lambda(R)/E2A colocalizations in G(1) and impairs diversification but not transcription of lambda(R). Thus, E2A acts in cis to promote Ig gene diversification, and G(1) phase is the critical window for E2A action.

The MRE11-RAD50-NBS1 complex accelerates somatic hypermutation and gene conversion of immunoglobulin variable regions.

Targeted diversification of immunoglobulin variable regions is induced by activation-induced deaminase and may occur by either somatic hypermutation or gene conversion. MRE11-RAD50-NBS1 (MRN) is a ubiquitous and conserved nuclease complex critical for DNA break repair and is essential in class-switch recombination. Here we show that ectopic expression of NBS1, the regulatory subunit of MRN, accelerated hypermutation in the human B cell line Ramos and accelerated gene conversion in the chicken B cell line DT40. In both cases, accelerated diversification depended on MRN complex formation. These data suggest that MRN promotes DNA cleavage and/or mutagenic repair of lesions initiated by activation-induced deaminase, acting in the shared pathway of immunoglobulin gene diversification.