A Randomized Trial of Two Remote Health Care Delivery Models on the Uptake of Genetic Testing and Impact on Patient-Reported Psychological Outcomes in Families With Pancreatic Cancer: The Genetic Education, Risk Assessment, and Testing (GENERATE) Study

BACKGROUND & AIMS

Genetic testing uptake for cancer susceptibility in family members of patients with cancer is suboptimal. Among relatives of patients with pancreatic ductal adenocarcinoma (PDAC), The GENetic Education, Risk Assessment, and TEsting (GENERATE) study evaluated 2 online genetic education/testing delivery models and their impact on patient-reported psychological outcomes.

METHODS

Eligible participants had ≥1 first-degree relative with PDAC, or ≥1 first-/second-degree relative with PDAC with a known pathogenic germline variant in 1 of 13 PDAC predisposition genes. Participants were randomized by family, between May 8, 2019, and June 1, 2021. Arm 1 participants underwent a remote interactive telemedicine session and online genetic education. Arm 2 participants were offered online genetic education only. All participants were offered germline testing. The primary outcome was genetic testing uptake, compared by permutation tests and mixed-effects logistic regression models. We hypothesized that Arm 1 participants would have a higher genetic testing uptake than Arm 2. Validated surveys were administered to assess patient-reported anxiety, depression, and cancer worry at baseline and 3 months postintervention.

RESULTS

A total of 424 families were randomized, including 601 participants (n = 296 Arm 1; n = 305 Arm 2), 90% of whom completed genetic testing (Arm 1 [87%]; Arm 2 [93%], P = .014). Arm 1 participants were significantly less likely to complete genetic testing compared with Arm 2 participants (adjusted ratio [Arm1/Arm2] 0.90, 95% confidence interval 0.78-0.98). Among participants who completed patient-reported psychological outcomes questionnaires (Arm 1 [n = 194]; Arm 2 [n = 206]), the intervention did not affect mean anxiety, depression, or cancer worry scores.

CONCLUSIONS

Remote genetic education and testing can be a successful and complementary option for delivering genetics care. (Clinicaltrials.gov, number NCT03762590).

PREMM5 distinguishes sporadic from Lynch syndrome-associated MMR-deficient/MSI-high colorectal cancer

Current algorithms for diagnosing Lynch syndrome (LS) include multistep molecular tumor tests to distinguish LS-associated from sporadic colorectal cancer (CRC), which add cost and complexity to the evaluation. We hypothesized that PREMM5, a clinical LS prediction tool, could be an alternative approach to screen for LS, thereby lessening the need for specialized molecular diagnostics. We reviewed a consecutively ascertained institutional cohort of 1058 CRC patients on whom pathologic and clinical data were available, including prior LS germline testing. Data from MMR-D/MSI-H CRC patients were reviewed and PREMM5 scores were calculated for each individual. Using a PREMM5 score cutoff ≥ 2.5% to characterize the need for germline testing, we determined the rate of pathogenic/likely pathogenic germline variants (PGVs) in LS genes in patients with PREMM5 scores ≥ 2.5% versus < 2.5%. Sensitivity and negative predictive values (NPV) of PREMM5 were calculated for all MMR-D/MSI-H CRC patients, and those with MLH1-deficient CRC. MMR IHC and/or MSI results were available on 572/1058 cases. We identified 74/572 (12.9%) cases as MMR-D/MSI-H, of which 28/74 (37.8%) harbored a LS PGV. 11/49 (22.4%) patients with MLH1-deficient CRC harbored a LS PGV. PREMM5 had 100% sensitivity (95% CI: 87.7-100 for any MMR-D/MSI-H; 95% CI: 71.5-100 for MLH1-deficient CRC) and 100% NPV (95% CI: 83.2-100 for any MMR-D/MSI-H; 95% CI: 82.4-100 for MLH1-deficient CRC) for identifying LS PGVs in these cohorts. PREMM5 accurately distinguishes LS- from non-LS-associated MMR-D/MSI-H CRC without additional somatic molecular testing. These findings are particularly relevant for limited-resource settings where advanced molecular diagnostics may be unavailable.

Development and Validation of the PREMMplus Model for Multigene Hereditary Cancer Risk Assessment

PURPOSE

With the availability of multigene panel testing (MGPT) for hereditary cancer risk assessment, clinicians need to assess the likelihood of pathogenic germline variants (PGVs) across numerous genes in parallel. This study's aim was to develop and validate a clinical prediction model (PREMMplus) for MGPT risk assessment.

MATERIALS AND METHODS

PREMMplus was developed in a single-institution cohort of 7,280 individuals who had undergone MGPT. Logistic regression models with Least Absolute Shrinkage and Selection Operator regularization were used to examine candidate predictors (age, sex, ethnicity, and personal/family history of 18 cancers/neoplasms) to estimate one's likelihood of carrying PGVs in 19 genes (broadly categorized by phenotypic overlap and/or relative penetrance: 11 category A [APC, BRCA1/2, CDH1, EPCAM, MLH1, MSH2, MSH6, biallelic MUTYH, PMS2, and TP53] and eight category B genes [ATM, BRIP1, CDKN2A, CHEK2, PALB2, PTEN, RAD51C, and RAD51D]). Model performance was validated in nonoverlapping data sets of 8,691 and 14,849 individuals with prior MGPT ascertained from clinic- and laboratory-based settings, respectively.

RESULTS

PREMMplus (score ≥ 2.5%) had 93.9%, 91.7%, and 89.3% sensitivity and 98.3%, 97.5%, and 97.8% negative-predictive value (NPV) for identifying category A gene PGV carriers in the development and validation cohorts, respectively. PREMMplus assessment (score ≥ 2.5%) had 89.9%, 85.6%, and 84.2% sensitivity and 95.0%, 93.5%, and 93.5% NPV, respectively, for identifying category A/B gene PGV carriers. Decision curve analyses support MGPT for individuals predicted to have ≥ 2.5% probability of a PGV.

CONCLUSION

PREMMplus accurately identifies individuals with PGVs in a diverse spectrum of cancer susceptibility genes with high sensitivity/NPV. Individuals with PREMMplus scores ≥ 2.5% should be considered for MGPT.

Abstract A029: A randomized study of two Strategies of remote Genetic Education, Risk Assessment, and Testing (GENERATE) for family members of patients with pancreatic cancer

Background: Uptake of genetic testing for cancer susceptibility in family members of cancer patients is suboptimal. The GENetic Education, Risk Assessment, and TEsting (GENERATE) study evaluated two strategies of remote genetic education and testing in relatives of pancreatic ductal adenocarcinoma (PDAC) patients. Methods: Eligible participants had: a first-degree relative with PDAC or had a known pathogenic germline variant (PGV) in one of thirteen PDAC predisposition genes (APC, ATM, BRCA1, BRCA2, CDKN2A, EPCAM, MLH1, MSH2, MSH6, PALB2, PMS2, STK11, or TP53) and a first- or second-degree relative with PDAC. Participants were cluster-randomized by family into one of two arms. Arm 1 included an interactive telemedicine session with a genetic counselor, followed by genetic testing at a commercial laboratory. Arm 2 involved remote online genetic education and testing at the commercial laboratory without the interactive session. The primary outcome was uptake of genetic testing across study arms, which was compared by permutation tests and mixed-effects logistic regression models. Results: Between 5/8/2019 and 6/1/2021, 424 families were randomized, including 601 participants (n=296 Arm 1; n=305 Arm 2). The uptake of genetic testing was 87% (257/296) in Arm 1 and 93% (284/305) in Arm 2 (p=0.014). Participants in Arm 1 were significantly less likely to obtain genetic testing compared to Arm 2 (Adjusted ratio [Arm1/Arm2] 0.90, 95% confidence interval 0.78-0.98). BRCA2, ATM, CDKN2A and PALB2 were the most common PDAC susceptibility genes in which PGVs were identified. Conclusions: Remote methods of genetic education and testing are successful alternatives to traditional germline susceptibility testing.

Citation Format: Nicolette J. Rodriguez, C. Sloane Furniss, Matthew B. Yurgelun, Chinedu Ukaegbu, Pamela E. Constantinou, Ileana Fortes, Alyson Caruso, Alison N. Schwartz, Jill E. Stopfer, Meghan Underhill-Blazey, Barbara Kenner, Scott H. Nelson, Sydney Okumura, Alicia Y. Zhou, Tara B. Coffin, Hajime Uno, Miki Horiguchi, Allyson J. Ocean, Florencia McAllister, Andrew M. Lowy, Scott M. Lippman, Alison P. Klein, Lisa Madlensky, Gloria M. Petersen, Judy E. Garber, Michael G. Goggins, Anirban Maitra, Sapna Syngal. A randomized study of two Strategies of remote Genetic Education, Risk Assessment, and Testing (GENERATE) for family members of patients with pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr A029.

Novel Models of Genetic Education and Testing for Pancreatic Cancer Interception: Preliminary Results from the GENERATE Study

Up to 10% of patients with pancreatic ductal adenocarcinoma (PDAC) carry underlying germline pathogenic variants in cancer susceptibility genes. The GENetic Education Risk Assessment and TEsting (GENERATE) study aimed to evaluate novel methods of genetic education and testing in relatives of patients with PDAC. Eligible individuals had a family history of PDAC and a relative with a germline pathogenic variant in APC, ATM, BRCA1, BRCA2, CDKN2A, EPCAM, MLH1, MSH2, MSH6, PALB2, PMS2, STK11, or TP53 genes. Participants were recruited at six academic cancer centers and through social media campaigns and patient advocacy efforts. Enrollment occurred via the study website (https://GENERATEstudy.org) and all participation, including collecting a saliva sample for genetic testing, could be done from home. Participants were randomized to one of two remote methods that delivered genetic education about the risks of inherited PDAC and strategies for surveillance. The primary outcome of the study was uptake of genetic testing. From 5/8/2019 to 5/6/2020, 49 participants were randomized to each of the intervention arms. Overall, 90 of 98 (92%) of randomized participants completed genetic testing. The most frequently detected pathogenic variants included those in BRCA2 (N = 15, 17%), ATM (N = 11, 12%), and CDKN2A (N = 4, 4%). Participation in the study remained steady throughout the onset of the Coronavirus disease (COVID-19) pandemic. Preliminary data from the GENERATE study indicate success of remote alternatives to traditional cascade testing, with genetic testing rates over 90% and a high rate of identification of germline pathogenic variant carriers who would be ideal candidates for PDAC interception approaches. PREVENTION RELEVANCE: Preliminary data from the GENERATE study indicate success of remote alternatives for pancreatic cancer genetic testing and education, with genetic testing uptake rates over 90% and a high rate of identification of germline pathogenic variant carriers who would be ideal candidates for pancreatic cancer interception.

Comparison of Colorectal and Endometrial Microsatellite Instability Tumor Analysis and Premm5 Risk Assessment for Predicting Pathogenic Germline Variants on Multigene Panel Testing

PURPOSE

Tumor testing for microsatellite instability and/or mismatch repair-deficiency (MSI/IHC) and clinical prediction models effectively screen for Lynch syndrome (LS)-associated colorectal cancer (CRC) and endometrial cancer (EC), but they have not been assessed for their ability to identify non-LS forms of inherited risk. The aim of this study was to compare MSI/IHC and the PREMM5 prediction model to identify carriers of LS and non-LS pathogenic variants (PVs) among patients with CRC and EC.

PATIENTS AND METHODS

Data were retrospectively analyzed from two single-institution cohorts: 706 patients with CRC and/or EC referred for genetic evaluation/testing (high-risk cohort) and 1,058 consecutively ascertained patients with CRC (oncology clinic cohort), unselected for familial risk. All participants underwent germline multigene panel testing. PREMM5 scores were calculated from personal/family cancer history. The primary outcome was the proportion of individuals with germline PVs (LS PVs, high-penetrance PVs, and any PVs) who had abnormal MSI/IHC testing and/or PREMM5 score ≥ 2.5%.

RESULTS

MSI/IHC and PREMM5 had comparable sensitivity for identifying LS carriers in high-risk (89.3% v 85.7%; P = .712) and oncology clinic patients (96.6% v 96.6%; P = 1.000), although MSI/IHC had significantly superior specificity for LS (81.3% v 20.1%; P < .001; 92.3% v 24.3%; P < .001). In both cohorts, PREMM5 had superior sensitivity to MSI/IHC at identifying patients with any high-penetrance PVs and any low-, moderate-, and high-penetrance PVs. Among patients with normal MSI/IHC, PREMM5 identified 84.2% and 83.3% of high-risk patients with CRC/EC and oncology clinic CRC patients with high-penetrance PVs, respectively.

CONCLUSION

MSI/IHC and PREMM5 effectively identify patients with CRC and/or EC with LS, although MSI/IHC has better specificity for LS. Because PREMM5 identifies non-LS, high-penetrance germline PVs, patients with CRC and/or EC with PREMM5 score ≥ 2.5%, including those with normal MSI/IHC, should be offered multigene panel testing.

Development and validation of the PREMMplus clinical prediction model for multigene hereditary cancer risk assessment

1579

Background: Current clinical prediction models provide syndrome-specific numeric estimates of an individual's likelihood of having a specific hereditary cancer syndrome (e.g., PREMM5 for Lynch syndrome; BRCAPRO for BRCA1/2). With the emergence of multigene panel testing (MGPT), there is a need to evaluate individuals' risk of carrying a pathogenic variant in a diverse array of cancer susceptibility genes in parallel. This study’s aim was to develop and validate the PREMMplus clinical prediction model for multigene cancer risk assessment. Methods: PREMMplus was developed in a cohort of 7296 individuals who had undergone germline MGPT at a single center. Logistic regression models were used to examine candidate predictive variables – including age, sex, ethnicity, and personal/family history of cancer – to provide a numeric estimate of an individual’s likelihood of carrying a pathogenic/likely pathogenic germline variant in one of 18 cancer susceptibility genes (11 high- [ APC, BRCA1/2, CDH1, EPCAM, MLH1, MSH2, MSH6, biallelic MUTYH, PMS2, and TP53] and 7 moderate-penetrance [ ATM, CDKN2A, CHEK2, PALB2, PTEN, RAD51C, and RAD51D]). Model performance was validated in an independent dataset of 14845 individuals who had undergone MGPT at a commercial laboratory. Results: Using clinical characteristics, including personal/family history of 18 cancers plus colorectal adenoma burden, PREMMplus demonstrated an excellent ability to predict pathogenic variants in high penetrance genes at 90% sensitivity. PREMMplus had acceptable performance with the addition of 7 moderate penetrance genes. PREMMplus was well-calibrated and demonstrated comparable performance in the external validation dataset. Conclusions: PREMMplus is the first validated risk assessment model to quantify an individual’s likelihood of carrying pathogenic variants in a wide diversity of cancer risk genes, and can be used to select individuals who should undergo MGPT. As expected, PREMMplus’s discriminatory capacity was reduced with the inclusion of moderate penetrance cancer risk genes. [Table: see text]

Improving cascade genetic testing for families with inherited pancreatic cancer (PDAC) risk: The GENetic Education, Risk Assessment and TEsting (GENERATE) study

TPS779

Background: 4-10% of PDAC patients harbor pathogenic germline variants in cancer susceptibility genes, including APC, ATM, BRCA1, BRCA2, CDKN2A, EPCAM, MLH1, MSH2, MSH6, PALB2, PMS2, STK11, and TP53. For families with such pathogenic variants, the greatest potential impact of germline testing is to identify relatives with the same variant (cascade testing), thereby providing the opportunity for early detection and interception of PDAC and other associated cancers. Numerous factors limit cascade testing in real-world practice, including family dynamics, widespread geographic distribution of relatives, access to genetic services, and misconceptions about the importance of germline testing, such that the preventive benefits of cascade testing are often not fully realized. The primary aim of this study is to analyze two alternative strategies for cascade testing in families with inherited PDAC risk. Methods: 1000 individuals with a confirmed pathogenic germline variant in any of the above genes in a 1st/2nd degree relative and a 1st/2nd degree relative with PDAC will be remotely enrolled through the study website (www.GENERATEstudy.org) and randomized between two methods of cascade testing (individuals with prior genetic testing will be ineligible): Arm 1 will undergo pre-test genetic education with a pre-recorded video and live interactive session with a genetic counselor via a web-based telemedicine platform (Doxy.me), followed by germline testing through Color Genomics; Arm 2 will undergo germline testing through Color Genomics without dedicated pre-test genetic education. Color Genomics will disclose results to study personnel and directly to participants in both arms. All participants will have the option of pursuing additional telephone-based genetic counseling through Color Genomics. The primary outcome will be uptake of cascade testing. Secondary outcomes will include self-reported genetic knowledge, cancer worry, distress, decisional preparedness, familial communication, and screening uptake, which will be measured via longitudinal surveys. Enrollment is underway nationwide as of May, 2019. Clinical trial information: NCT03762590.

Improving cascade genetic testing for families with inherited pancreatic cancer (PDAC) risk: The genetic education, risk assessment and testing (GENERATE) study

TPS4162

Background: 4-10% of PDAC patients harbor pathogenic germline variants in cancer susceptibility genes, including APC, ATM, BRCA1, BRCA2, CDKN2A, EPCAM, MLH1, MSH2, MSH6, PALB2, PMS2, STK11, and TP53. For families with such pathogenic variants, the greatest potential impact of germline testing is to identify relatives with the same pathogenic variant (cascade testing), thereby providing the opportunity for early detection and cancer interception of PDAC and other associated malignancies. Numerous factors limit cascade testing in real-world practice, including family dynamics, widespread geographic distribution of relatives, access to genetic services, and misconceptions about the importance of germline testing, such that the preventive benefits of cascade testing are often not fully realized. The primary aim of this study is to analyze two alternative strategies for cascade testing in families with inherited PDAC susceptibility. Methods: 1000 individuals (from approximately 200 families) with a confirmed pathogenic germline variant in any of the above genes in a 1st/2nd degree relative and a 1st/2nd degree relative with PDAC will be remotely enrolled through the study website (www.generatestudy.org) and randomized between two different methods of cascade testing (individuals with prior genetic testing will be ineligible): Arm 1 will undergo pre-test genetic education with a pre-recorded video and live interactive session with a genetic counselor via a web-based telemedicine platform (Doxy.me), followed by germline testing through Color Genomics; Arm 2 will undergo germline testing through Color Genomics without dedicated pre-test genetic education. Color Genomics will disclose results to study personnel and directly to participants in both arms. Participants in both arms will have the option of pursuing additional telephone-based genetic counseling through Color Genomics. The primary outcome will be uptake of cascade testing. Secondary outcomes will include participant self-reported genetic knowledge, cancer worry, distress, decisional preparedness, familial communication, and screening uptake, which will be measured via longitudinal surveys. Enrollment will begin February, 2019. Clinical trial information: NCT03762590.

Human papillomavirus-16 modifies the association between fruit consumption and head and neck squamous cell carcinoma

Human papillomavirus-16 (HPV-16) is a risk factor for head and neck squamous cell carcinoma (HNSCC). HPV-positive cancers have distinct disease cofactors and improved survival following treatment. There is conflicting evidence of a protective association of fruit consumption with HNSCC. As HPV-related disease is clinically distinct, we investigated whether the association between fruit consumption and HNSCC risk was modified by exposure to HPV-16. We studied 270 cases and 493 controls with fruit intake information and known HPV-16 antibody status. Cases were identified at nine Boston-area medical facilities between 1999 and 2003. Controls were randomly selected from the greater population and frequency matched to cases by age, gender, and town of residence. Controlling for age, gender, race, smoking, alcohol, total energy intake, body mass index, and education, the seronegative individuals had a significantly lower risk of HNSCC with increasing total fruit consumption [odds ratio (OR)(tertile 2), 0.60; 95% confidence interval (95% CI), 0.38-0.95; OR(tertile 3), 0.57; 95% CI, 0.35-0.95] and specifically increasing citrus fruit consumption (OR(tertile 2), 0.61; 95% CI, 0.39-0.97; OR(tertile 3), 0.59; 95% CI, 0.37-0.96). However, among the seropositive, risk increased with greater fruit consumption (OR(tertile 2), 2.27; 95% CI, 0.92-5.58; OR(tertile 3), 1.40; 95% CI, 0.55-3.59) and citrus fruit consumption (OR(tertile 2), 3.35; 95% CI, 1.36, 8.24; OR(tertile 3), 3.15; 95% CI, 1.23-8.08). This interaction was statistically significant (P < 0.05), showing that fruit consumption was associated with a reduced HNSCC risk among HPV-16-seronegative individuals but an increased HNSCC risk among the HPV-16-seropositive individuals. These findings suggest that dietary factors dramatically alter the pattern of occurrence of HPV-associated HNSCC and show that viral-related disease is clinically and etiologically distinct.

Human papillomavirus 6 seropositivity is associated with risk of head and neck squamous cell carcinoma, independent of tobacco and alcohol use

BACKGROUND

The risk of head and neck squamous cell carcinoma (HNSCC) associated with common human papillomavirus types has not been well defined.

METHODS

We conducted a case-control study of 1034 individuals (486 incident cases diagnosed with HNSCC and 548 population-based controls matched to cases by age, gender, and town of residence) in Greater Boston, MA. Sera were tested for antibodies to human papillomavirus (HPV)6, HPV11, HPV16, and HPV18 L1.

RESULTS

HPV6 antibodies were associated with an increased risk of pharyngeal cancer [odds ratio (OR)=1.6, 1.0-2.5], controlling for smoking, drinking, and HPV16 seropositivity. In HPV16-seronegative subjects, high HPV6 titer was associated with an increased risk of pharyngeal cancer (OR=2.3, 1.1-4.8) and oral cancer (OR=1.9, 1.0-3.6), suggesting that the cancer risk associated with HPV6 is independent of HPV16. There was no association between smoking and alcohol use and HPV6 serostatus. Further, the risk of pharyngeal cancer associated with heavy smoking was different among HPV6-seronegative (OR 3.1, 2.0-4.8) and HPV6-seropositive subjects (OR=1.6, 0.7-3.5), while heavy drinking also appears to confer differing risk among HPV6-negative (OR 2.3, 1.5-3.7) and -positive subjects (OR=1.3, 0.6-2.9).

CONCLUSIONS

There may be interactions between positive serology and drinking and smoking, suggesting that the pathogenesis of human papillomavirus in HNSCC involves complex interactions with tobacco and alcohol exposure.

Line region hypomethylation is associated with lifestyle and differs by human papillomavirus status in head and neck squamous cell carcinomas

Genomic hypomethylation is a hallmark of essentially all cancers, but the degree of this hypomethylation differs among individual tumors. Little work has explored what leads to these differences and or asked whether they are clinically meaningful. In this study of head and neck squamous cell carcinoma, we assessed hypomethylation in tumors using a semiquantitative fragment analysis approach to determine the relative methylation status of the line retroviral element LRE1 (Line-1.2). Because this is an established marker of genomic methylation status, we examined the relationship between the relative methylation, patient demographics, and other risk factors for head and neck squamous cell carcinoma. We determined relative methylation status for 303 patients, 193 of which had complete data for all variables of interest. Using a generalized linear model, we found that patient body mass index was significantly positively associated with tumor LRE1 methylation level. Smoking duration, particularly in tumors lacking human papillomavirus (HPV) DNA, was significantly negatively associated with relative methylation level. Having previously assessed relative methylation in blood-derived DNA, we compared tumor with the blood DNA methylation level and observed these to be independent. Finally, the lower LRE1 methylation in patients whose tumors were HPV DNA negative was associated with poorer patient survival (hazard ratio, 1.6; 95% confidence interval, 1.0-2.6). These findings suggest that HPV-associated tumors differ molecularly from those arising after heavy tobacco use and that this epigenetic alteration may affect survival in HPV-negative patients already exhibiting a more aggressive disease.

Global DNA methylation level in whole blood as a biomarker in head and neck squamous cell carcinoma

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is commonly associated with tobacco and alcohol exposures, although dietary factors, particularly folate, and human papillomavirus, are also risk factors. Epigenetic alterations are increasingly implicated in the initiation and progression of cancer. Genome-wide (global) hypomethylation seems to occur in early neoplasia and is a feature of genomic DNA derived from solid tumor tissues, including HNSCC. This study aimed to determine whether global methylation in DNA derived from whole blood, a proxy tissue, is associated with HNSCC and to assess potential modification of this property by environmental or behavioral risk factors.

METHODS

Global DNA methylation levels were assessed using a modified version of the combined bisulfite restriction analysis of the LRE1 sequence in a population-based case-control study of HNSCC from the Boston area.

RESULTS

Hypomethylation lead to a significant 1.6-fold increased risk for disease (95% confidence interval, 1.1-2.4), in models controlled for other HNSCC risk factors. Smoking showed a significant differential effect (P < 0.03) on blood relative methylation between cases and controls. Furthermore, in cases, variant genotype in the MTHFR gene and low folate intake showed relationships with decreased global methylation, whereas in controls, antibody response to human papillomavirus 16 was associated with an increased global methylation level.

DISCUSSION

DNA hypomethylation in nontarget tissue was independently associated with HNSCC and had a complex relationship with the known risk factors associated with the genesis of HNSCC.

Human papillomavirus 16 and head and neck squamous cell carcinoma

Evidence suggests that human papillomavirus (HPV)16 seropositivity reflects past HPV16 exposure and is associated with risk for head and neck squamous cell carcinoma (HNSCC). Our objectives were to test the hypothesis that HPV16 seropositivity is associated with risk for HNSCC, to correlate HPV16 seropositivity with HPV16 tumor DNA, and to correlate HPV16 seropositivity and HPV16 DNA with sexual history and patient survival. In a case-control study of approximately 1,000 individuals, we assessed serology to the HPV16 L1 protein and in cases only, assayed tumors for HPV16 DNA. HPV16 seropositivity was associated with 1.5- and 6-fold risks for tumors of the oral cavity and pharynx, respectively. There was a dose response trend for HPV16 titer and increasing risk of HNSCC (p < 0.0001) and HPV16 tumor DNA (p < 0.0001). In cases, HPV16 DNA and seropositivity were significantly associated with sexual activity; odds ratios (ORs) of 12.8 and 3.7 were observed for more than 10 oral sexual partners and ORs of 4.5 and 3.2 were associated with a high number of lifetime sexual partners, respectively. Finally, HPV16 seropositivity and HPV16 tumor DNA were associated with hazard ratios of 0.4 and 0.5, respectively, indicating better survival for HPV positive individuals. HPV16 seropositivity was associated with risk for HNSCC, with greatest risk for pharyngeal cancer. We observed dose response relationships between serology titer and both risk for HNSCC and HPV16 tumor DNA. In cases, HPV16 tumor DNA and positive serology were associated with sexual history and improved disease free survival.

Both binding sites of the starch-binding domain of Aspergillus niger glucoamylase are essential for inducing a conformational change in amylose

The interaction of the two binding sites of the starch-binding domain (SBD) of Aspergillus niger glucoamylase 1 (GA-I) with substrate has been investigated by using atomic force microscopy (AFM) and UV difference spectroscopy in combination with site-specific mutants of both SBD and GA-I. The SBD possesses two binding sites with distinct affinities towards the soluble linear substrate maltoheptaose; dissociation constants (K(d)) of 17 and 0.95 microM were obtained for W563 K (binding site 2 mutant) and W590 K (binding site 1 mutant), respectively, compared to an apparent K(d) of 23 microM for the wild-type SBD. Further, the two sites are almost but not totally independent of each other for binding, since abolishing one site does not prevent the amylose chain binding to the other site. Using AFM, we show that the amylose chains undergo a conformational change to form loops upon binding to the SBD, using either the recombinant wild-type SBD or a catalytically inactive mutant of GA-I. This characteristic conformation of amylose is lost when one of the SBD binding sites is eliminated by site-directed mutagenesis, as seen with the mutants W563 K or W590 K. Therefore, although each binding site is capable of simple binding to a ligand, both sites must be functional in order to induce a gross conformational change of the amylose molecules. Taken together these data suggest that for the complex with soluble amylose, SBD binds to a single amylose chain, site 1 being responsible for the initial recognition of the chain and site 2 being involved in tighter binding, leading to the circularisation of the amylose chain observed by AFM. Binding of the SBD to the amylose chain results in a novel two-turn helical amylose complex structure. The binding of parallel amylosic chains to the SBD may provide a basis for understanding the role of the SBD in facilitating enzymatic degradation of crystalline starches by glucoamylase 1.

Function of conserved tryptophans in the Aspergillus niger glucoamylase 1 starch binding domain

Nuclear magnetic resonance (NMR) and ultraviolet (UV) difference spectroscopy were used to assess the role of a number of tryptophan residues in the granular starch binding domain (SBD) of glucoamylase 1 from Aspergillus niger. Wild-type SBD and three variant (W563K, W590K, and W615K) proteins were produced using an A. niger expression system. Titration studies were conducted with beta-cyclodextrin (betaCD), a cyclic analogue of starch, as the ligand. The NMR studies show that the W563K and W590K variants only bind 1 equiv while the wild-type protein forms a 2:1 (ligand:protein) complex. It also clearly demonstrates the abolition of binding at site 1 and site 2 in W590K and W563K, respectively. UV difference spectroscopy was used to calculate dissociation constants with addition of betaCD: 14.4 microM (apparent) for the wild type, 28.0 microM for W563K, and 6.4 microM for W590K. The implication of this is that the two binding sites have unequal contributions to the overall binding of the SBD which may be related to functional differences between the two binding sites. The low stability of the third variant, W615K, suggests that this tryptophan is not involved in binding but has an essential structural role.

Isolation and characterisation of a linked cluster of genes from Agrobacterium tumefaciens encoding proteins involved in flagellar basal-body structure

We report the DNA sequence of 7205 bp of the Agrobacterium tumefaciens chromosome. This contains a putative operon encoding homologues of the flagellar rod and associated proteins FlgBCG and FliE, the L and P ring proteins (FlgHI) a possible flagellum-specific export protein FliP, and two proteins of unknown function, FlgA and FliL. Several of these genes have overlapping stop and start codons. Three non-flagellate Tn5-induced mutations map to this operon: fla-11 to the first gene, encoding the rod protein FlgB; fla-15 to flgA; and fla-12 to fliL. A site-specific mutation introduced into the final gene in this cluster, fliP, also resulted in a non-flagellate phenotype. This indicates that the operon is expressed, and that at least FlgB, FlgA, FliL and FliP are required for flagellar assembly in A. tumefaciens. The bulk of this operon is conserved in the same order in Rhizobium meliloti.

The manipulation of DNA with restriction enzymes in low water systems

The cleavage of phage lambda (lambda) DNA by the restriction enzyme HindIII in low water systems has been investigated. Two types of low water systems have been studied--those which contain a surfactant in a reverse micelle environment and a surfactant-free system in which a solid support (celite) is used. The effect of the surfactants themselves in a normal aqueous environment has also been studied. Charged surfactants were found to greatly inhibit HindIII activity in aqueous buffer, while non-ionic surfactants did not affect either the activity or the specificity of the restriction enzyme. The rate of cleavage by HindIII in a reverse micelle system consisting of sodium dioctylsulphosuccinate is very slow, however, in a Triton B system the expected fragments are observed. In a surfactant-free low water environment, cleavage occurs at the expected sites but in a different order to that observed in normal aqueous systems. These results suggest that DNA tertiary structure in low water systems is different to that in aqueous solution and that this influences cleavage by the restriction enzyme HindIII.