Racial and Ethnic Differences in the Epidemiology and Genomics of Lung Cancer.

BACKGROUND: Lung cancer is the most common cancer in the world. In addition to the geographical and sex-specific differences in the incidence, mortality, and survival rates of lung cancer, growing evidence suggests that racial and ethnic differences exist. METHODS: We reviewed published data related to racial and ethnic differences in lung cancer. RESULTS: Current knowledge and substantive findings related to racial and ethnic differences in lung cancer were summarized, focusing on incidence, mortality, survival, cigarette smoking, prevention and early detection, and genomics. Systems-level and health care professional-related issues likely to contribute to specific racial and ethnic health disparities were also reviewed to provide possible suggestions for future strategies to reduce the disproportionate burden of lung cancer. CONCLUSIONS: Although lung carcinogenesis is a multifactorial process driven by exogenous exposures, genetic variations, and an accumulation of somatic genetic events, it appears to have racial and ethnic differences that in turn impact the observed epidemiological differences in rates of incidence, mortality, and survival.

Construction and Validation of a Multi-Institutional Tissue Microarray of Invasive Ductal Carcinoma From Racially and Ethnically Diverse Populations.

BACKGROUND: The scarcity of tissues from racial and ethnic minorities at biobanks poses a scientific constraint to research addressing health disparities in minority populations. METHODS: To address this gap, the Minority Biospecimen/Biobanking Geographic Management Program for region 3 (BMaP-3) established a working infrastructure for a "biobanking" hub in the southeastern United States and Puerto Rico. Herein we describe the steps taken to build this infrastructure, evaluate the feasibility of collecting formalin-fixed, paraffin-embedded tissue blocks and associated data from a single cancer type (breast), and create a web-based database and tissue microarrays (TMAs). RESULTS: Cancer registry data from 6 partner institutions were collected, representing 12,408 entries from 8,279 unique patients with breast cancer (years 2001-2011). Data were harmonized and merged, and deidentified information was made available online. A TMA was constructed from formalin-fixed, paraffin-embedded samples of invasive ductal carcinoma (IDC) representing 427 patients with breast cancer (147 African Americans, 168 Hispanics, and 112 non-Hispanic whites) and was annotated according to biomarker status and race/ethnicity. Biomarker analysis of the TMA was consistent with the literature. CONCLUSIONS: Contributions from participating institutions have facilitated a robust research tool. TMAs of IDC have now been released for 5 projects at 5 different institutions.

African Americans' and Hispanics' information needs about cancer care.

Few studies have reported on African American and Hispanic (AA and H) populations' informational needs when seeking cancer care at an institution that offers clinical trials. Moffitt Cancer Center (MCC) sought to identify and examine the decision making process, the perceptions, and the preferred channels of communication about cancer care services for AA and H communities in order to develop a list of marketing recommendations. Five focus groups (N = 45) consisting of two AA and three H were conducted in four counties of the MCC catchment area in Tampa, FL. Participants were asked about their perceptions, knowledge, attitudes, and beliefs about cancer care and MCC. Focus groups were audio-recorded and verbatim transcripts were analyzed using content analysis. Similarities in responses were found between AA and H participants. Participants received general health and cancer information from media sources and word of mouth and preferred to hear patient testimonials. There were concerns about costs, insurance coverage, and the actual geographic location of the cancer center. In general, H participants were not opposed to participating in cancer clinical trials/research, whereas, AA participants were more hesitant. A majority of participants highly favored an institution that offered standard care and clinical trials. AA and H participants shared similar concerns and preferences in communication channels, but each group had specific informational needs. The perceptions and preferences of AA and H must be explored in order to successfully and efficiently increase cancer clinical trial participation.

Don't neglect cultural diversity in oncology care.

The growing Hispanic population in the United States mandates the need for oncology providers to become more familiar with disease patterns and cultural belief systems that can impact cancer care. "Culturally competent care" should be the mandate of all providers. This comprises awareness of cultural differences, communication in a manner that the patient understands, and respect.

Healthcare providers' knowledge and attitudes about rapid tissue donation (RTD): phase one of establishing a rapid tissue donation programme in thoracic oncology.

In preparation for the development of a rapid tissue donation (RTD) programme, we surveyed healthcare providers (HCPs) in our institution about knowledge and attitudes related to RTD with lung cancer patients. A 31-item web based survey was developed collecting data on demographics, knowledge and attitudes about RTD. The survey contained three items measuring participants' knowledge about RTD, five items assessing attitudes towards RTD recruitment and six items assessing HCPs' level of agreement with factors influencing decisions to discuss RTD. Response options were presented on a 5-point Likert scale. Ninety-one HCPs participated in the study. 66% indicated they had never heard of RTD prior to the survey, 78% rated knowledge of RTD as none or limited and 95.6% reported not having ethical or religious concerns about discussing RTD with patients. The majority were either not comfortable (17.8%) or not sure if they felt comfortable discussing RTD with cancer patients (42.2%). 56.1% indicated their knowledge of RTD would play an integral role in their decision to discuss RTD with patients. 71.4% reported concerns with RTD discussion and the emotional state of the patient. Physicians and nurses play an important role in initiating conversations about recruitment and donation to research that can ultimately influence uptake. Increasing HCP knowledge about RTD is a necessary step towards building an RTD programme. Our study provides important information about characteristics associated with low levels of knowledge and practice related to RTD where additional education and training may be warranted.

Spectrum of somatic mutational features of colorectal tumors in ancestrally diverse populations.

Ancestrally diverse and admixed populations, including the Hispanic/Latino/a/x/e community, are underrepresented in cancer genetic and genomic studies. Leveraging the Latino Colorectal Cancer Consortium, we analyzed whole exome sequencing data on tumor/normal pairs from 718 individuals with colorectal cancer (128 Latino, 469 non-Latino) to map somatic mutational features by ethnicity and genetic ancestry. Global proportions of African, East Asian, European, and Native American ancestries were estimated using ADMIXTURE. Associations between global genetic ancestry and somatic mutational features across genes were examined using logistic regression. TP53 , APC , and KRAS were the most recurrently mutated genes. Compared to non-Latino individuals, tumors from Latino individuals had fewer KRAS (OR=0.64, 95%CI=0.41-0.97, p=0.037) and PIK3CA mutations (OR=0.55, 95%CI=0.31-0.98, p=0.043). Genetic ancestry was associated with presence of somatic mutations in 39 genes (FDR-adjusted LRT p<0.05). Among these genes, a 10% increase in African ancestry was associated with significantly higher odds of mutation in KNCN (OR=1.34, 95%CI=1.09-1.66, p=5.74×10 -3 ) and TMEM184B (OR=1.53, 95%CI=1.10-2.12, p=0.011). Among RMGs, we found evidence of association between genetic ancestry and mutation status in CDC27 (LRT p=0.0084) and between SMAD2 mutation status and AFR ancestry (OR=1.14, 95%CI=1.00-1.30, p=0.046). Ancestry was not associated with tumor mutational burden. Individuals with above-average Native American ancestry had a lower frequency of microsatellite instable (MSI-H) vs microsatellite stable tumors (OR=0.45, 95%CI=0.21-0.99, p=0.048). Our findings provide new knowledge about the relationship between ancestral haplotypes and somatic mutational profiles that may be useful in developing precision medicine approaches and provide additional insight into genomic contributions to cancer disparities. Significance: Our data in ancestrally diverse populations adds essential information to characterize mutational features in the colorectal cancer genome. These results will help enhance equity in the development of precision medicine strategies.

Feasibility trial of a Spanish-language multimedia educational intervention.

BACKGROUND: Hispanic cancer patients are underrepresented in clinical trials; research suggests lack of knowledge and language barriers contribute to low accrual. Multimedia materials offer advantages to Hispanic populations because they have high acceptability, are easy to disseminate, and can be viewed with family. PURPOSE: Hispanic cancer patients and caregivers participated in focus groups to aid in developing a Spanish-language multimedia intervention to educate Hispanic cancer patients about clinical trials. We explored the feasibility of delivering the intervention in medical oncology clinics. METHODS: A total of 35 patients were randomized to either the multimedia intervention group (n = 18) or a control group (n = 17) who were asked to read the National Cancer Institute's Spanish-language clinical trials brochure. Self-reported data on knowledge about and attitudes toward clinical trials, self-efficacy for participating in a clinical trial, intention to participate in a clinical trial if asked, and receptivity to information about a clinical trial were collected at baseline and 10 days later. RESULTS: Delivery of the multimedia presentation in oncology clinics was feasible. The intervention group had more knowledge about clinical trials at follow-up than the control group; scores for intention to participate in a clinical trial by participants in the intervention group increased from 3.8 to 4.0 of a possible 5, but declined in the control group from 4.5 to 4.1. No statistically significant difference was detected between groups in scores for attitudes or self-efficacy for making a decision to participate in a clinical trial. LIMITATIONS: Our sample size was inadequate to identify differences between the informational methods. Although all patients were asked about their willingness to participate in a clinical trial, this decision was hypothetical. In addition, the study was conducted with a sample of Spanish-speaking Hispanic cancer patients at a comprehensive cancer center in Florida. Thus, the results may not generalize to other Hispanic populations. CONCLUSION: In the pilot project, we demonstrated the feasibility of delivering multimedia information to patients in medical oncology clinics. Because delivery in a clinical setting was found to be feasible, a larger study should be conducted to evaluate the efficacy of the multimedia intervention with respect to promoting accrual of Hispanic patients to clinical trials.

Altruism in terminal cancer patients and rapid tissue donation program: does the theory apply?

Rapid tissue donation (RTD) is an advancing oncology research procedure for collecting tumors, metastases, and unaffected tissue 2-6 h after death. Researchers can better determine rates of progression, response to treatment, and polymorphic differences among patients. Cancer patients may inquire about posthumous body donation for research to offer a personal contribution to research; however, there are barriers to recruiting for an RTD program. Physicians must reassure the patient that their treatment options and quality of care will not be compromised due to participating in RTD. In this commentary we discuss how theories of altruism may explain cancer patients' desire to participate in an RTD program, the ethical concerns of health care professionals and patients and the use of altruism as a recruitment strategy. We offer recommendations for examining the cultural and ethical climate of the institution prior to initiating such a program such as examining the relationship of healthcare professionals and patients, identifying ethical concerns, and examining ways to promote acceptance and buy-in across professionals, patients, and families.

Developing strategies for reducing cancer disparities via cross-institutional collaboration: outreach efforts for the partnership between the Ponce School of Medicine and the Moffitt Cancer Center.

The disproportionate burden of cancer among U.S. Hispanics is well documented. Historically, epidemiologic data on U.S. Hispanics and cancer have aggregated all Hispanics as one homogeneous group without appreciating the diversity of this population with regard to nativity (nationality/geographic origin). The authors report on the initial efforts of a collaborative academic institutional partnership between a minority-serving institution and a National Cancer Institute-designated cancer center to address cancer health disparities in two Hispanic communities in Puerto Rico and Florida. This article outlines the joint Outreach Program's initial collaborative strategies and activities in community outreach, cancer education, and research that mutually benefit both the Ponce (Puerto Rico) and Tampa (Florida) Hispanic communities. This partnership program used innovative multipronged community-engagement strategies in the two communities to reduce cancer health disparities. Specific projects and lessons learned from three outreach/cancer education projects and two pilot research projects are discussed. The challenges of balancing service and research agendas in communities with disparate levels of resources and infrastructure are summarized to inform future initiatives in this partnership, as well as serve as an example for similar minority-serving institution/cancer center partnerships to reduce cancer health disparities.

Enhancing oncology health care provider's sensitivity to cultural communication to reduce cancer disparities: a pilot study.

Under the auspices of a partnership grant to reduce cancer health disparities, Moffitt Cancer Center (MCC) partnered with the Ponce School of Medicine to identify the perceived cultural communication needs of MCC healthcare providers regarding Hispanic patients with limited or no English skills. Oncologists (N = 72) at MCC were surveyed to identify the specific areas of cultural communication techniques for which they desired to receive additional training. The majority of participants (66%) endorsed an interest in obtaining training to communicate difficult issues (terminal illness, controversial diagnosis) in a manner respectful to Hispanic culture. A workshop was conducted with providers (N = 55) to improve cultural communication between Hispanic patients and families focusing on culture, terminal illness, and communication strategies. Findings from a pre-post test indicate an overall positive response to the workshop. Results from this study can help inform future efforts to enhance cultural competency among health providers.

Correction: Transforming growth factor ß-induced epithelial-to-mesenchymal signature predicts metastasis-free survival in non-small cell lung cancer.

[This corrects the article DOI: 10.18632/oncotarget.26574.].

A community-based lung cancer rapid tissue donation protocol provides high-quality drug-resistant specimens for proteogenomic analyses.

BACKGROUND: For the advancement of cancer research, the collection of tissue specimens from drug-resistant tumors after targeted therapy is crucial. Although patients with lung cancer are often provided targeted therapy, post-therapy specimens are not routinely collected due to the risks of collection, limiting the study of targeted therapy resistance mechanisms. Posthumous rapid tissue donation (RTD) is an expedient collection process that provides an opportunity to understand treatment-resistant lung cancers. METHODS: Consent to participate in the thoracic RTD protocol was obtained during patient care. When death occurred, tumor and paired non-tumor, cytology, and blood specimens were collected within 48 hours and preserved as formalin-fixed and frozen specimens. Tissue sections were evaluated with hematoxylin and eosin staining and immunohistochemistry (IHC) against multiple biomarkers, including various programmed death ligand 1 (PD-L1) clones. Next-generation sequencing was performed on 13 specimens from 5 patients. RESULTS: Postmortem specimens (N = 180) were well preserved from 9 patients with lung cancer. PD-L1 IHC revealed heterogeneity within and between tumors. An AGK-BRAF fusion was newly identified in tumor from a donor with a known echinoderm microtubule-associated protein-like 4 to anaplastic lymphoma kinase (EML4-ALK) fusion and history of anaplastic lymphoma kinase (ALK) inhibitor therapy. RNA expression analysis revealed a clonal genetic origin of metastatic cancer cells. CONCLUSIONS: Post-therapy specimens demonstrated PD-L1 heterogeneity and an acyl glycerol kinase to B-rapidly accelerated fibrosarcoma (AGK-BRAF) fusion in a patient with an EML4-ALK-positive lung adenocarcinoma as a potential resistance mechanism to ALK inhibitor therapy. Rapid tissue donation collection of postmortem tissue from lung cancer patients is a novel approach to cancer research that enables studies of molecular evolution and drug resistance.

Use of biomarker testing in lung cancer among Puerto Rico and Florida Physicians: Results of a comparative study.

BACKGROUND: Lung cancer biomarker-driven therapies are the gold standard of treatment and recent studies suggest a higher prevalence of specific targetable biomarkers among Hispanic/Latinos (H/L) than Non-Hispanic Whites (NHW). The study aimed (1) to identify Florida (FL) and Puerto Rico (PR) physicians' knowledge and perceived value of newer genomic data regarding race/ethnicity in relation to optimal lung cancer treatment and survival; and (2) to identify modifiable practice barriers both across and within each location regarding biomarker testing in lung cancer. METHODS: A 25-item survey was administered to a stratified random sample of physicians in FL and PR (medical oncologists, radiation oncologists, pulmonologists, and pathologists). Questions targeted domains of biomarker knowledge, attitudes toward testing, barriers, and practice behaviors regarding lung cancer biomarker testing. RESULTS: The response rate was 45%. Participants identified guiding treatment decisions (82%) and personalizing treatments for patients (78%) as key benefits to mutation testing. PR physicians were more likely (p=0.022) to believe H/L had an elevated incidence of targetable epidermal growth factor receptor (EGFR) mutations compared to NHW. They also perceived lack of appropriate testing resources as a primary barrier compared to FL physicians (43.6% vs. 20.6%, p<0.001), whereas FL physicians identified mutation tests not conducted routinely as part of patient diagnosis as a primary barrier (43.1% vs 24.2%, p= 0.008). CONCLUSIONS: Practice behaviors differed by specialty and between locations, and differences were noted concerning physician's preferences for ordering mutation testing, indicating a clear need for education among physicians in both locations. IMPACT: Educating physicians regarding biomarker testing is imperative to improve patient care.

Transforming growth factor ß-induced epithelial-to-mesenchymal signature predicts metastasis-free survival in non-small cell lung cancer.

Transforming growth factor beta (TGFß) plays a key role in regulating epithelial-to-mesenchymal transition (EMT). A gene expression signature (TGFß-EMT) associated with TGFß-induced EMT activities was developed using human Non-Small Cell Lung Carcinoma (NSCLC) cells treated with TGFß-1 and subjected to Affymetrix microarray analysis. The final 105-probeset TGFß-EMT signature covers 77 genes, and a NanoString assay utilized a subset of 60 of these genes (TGFß-EMTN signature). We found that the TGFß-EMT and TGFß-EMTN gene signatures predicted overall survival (OS) and metastasis-free survival (MFS). The TGFß-EMT signature was validated as prognostic of 5-year MFS in 3 cohorts: a 133 NSCLC tumor dataset (P = 0.0002), a NanoString assays of RNA isolated from formalin-fixed paraffin-embedded samples from these same tumors (P = 0.0015), and a previously published NSCLC MFS dataset (P = 0.0015). The separation between high and low metastasis signature scores was higher at 3 years (ΔMFS TGFß-EMT = -28.6%; ΔMFS TGFß-EMTN = -25.2%) than at 5 years (ΔMFS TGFß-EMT = -18.6%; ΔMFS TGFß-EMTN = -11.8%). In addition, the TGFß-EMT signature correlated with whether the cancer had already metastasized or not at time of surgery in a colon cancer cohort. The results show that the TGFß-EMT signature successfully discriminated lung cancer cell lines capable of undergoing EMT in response to TGFß-1 and predicts MFS in lung adenocarcinomas. Thus, the TGFß-EMT signature has the potential to be developed as a clinically relevant predictive biomarker, for example to identify those patients with resected early stage lung cancer who may benefit from adjuvant therapy.

Characterization of epidermal growth factor receptor (EGFR) P848L, an unusual EGFR variant present in lung cancer patients, in a murine Ba/F3 model.

Lung cancer patients with mutations in epidermal growth factor receptor (EGFR) benefit from treatments targeting tyrosine kinase inhibitors (TKIs). However, both intrinsic and acquired resistance of tumors to TKIs are common, and EGFR variants have been identified that are resistant to multiple TKIs. In the present study, we characterized selected EGFR variants previously observed in lung cancer patients and expressed in a murine bone marrow pro-B Ba/F3 cell model. Among these EGFR variants, we report that an exon 20 deletion/insertion mutation S768insVGH is resistant to erlotinib (a first-generation TKI), but sensitive to osimertinib (a third-generation TKI). We also characterized a rare exon 21 germline variant, EGFR P848L, which transformed Ba/F3 cells and conferred resistance to multiple EGFR-targeting TKIs. Our analysis revealed that P848L (a) does not bind erlotinib; (b) is turned over less rapidly than L858R (a common tumor-derived EGFR mutation); (c) is not autophosphorylated at Tyr 1045 [the major docking site for Cbl proto-oncogene (c-Cbl) binding]; and (d) does not bind c-Cbl. Using viability assays including 300 clinically relevant targeted compounds, we observed that Ba/F3 cells transduced with EGFR P848L, S768insVGH, or L858R have very different drug-sensitivity profiles. In particular, EGFR P848L, but not L858R or S768insVGH, was sensitive to multiple Janus kinase 1/2 inhibitors. In contrast, cells driven by L858R, but not by P848L, were sensitive to multikinase MAPK/extracellular-signal-regulated kinase (ERK) kinase and ERK inhibitors including EGFR-specific TKIs. These observations suggest that continued investigation of rare TKI-resistant EGFR variants is warranted to identify optimal treatments for cancer.

Patient, caregiver and physician perspectives on participating in a thoracic rapid tissue donation program.

OBJECTIVE: The collection of posthumous tissue from advanced stage lung cancer patients is beneficial to medical science. Recruiting living patients to a Rapid Tissue Donation Program (RTD) poses several psychosocial challenges and little is known about perceptions of joining this type of program. This study qualitatively examined perceptions of advanced stage lung cancer patients (n=14) participating in a lung cancer RTD program, their NoK (n=11), and physicians (n=6) at the Thoracic Oncology Clinic at H. Lee Moffitt Cancer Center & Research Institute, Tampa, Florida USA. METHODS: Semi-structured interviews were conducted with participants and interview transcripts were analyzed using the constant comparison method. RESULTS: Majority of patients joined to give back to research, discussed participation with family members, and desired for family to receive information about the use of the tissue after their death. All participating NoK were supportive of their family member's decision. Physicians described the program as running smoothly, but provided suggestions for process improvements. CONCLUSION: Participants joined with intention to give back to research community and families were supportive of loved one's participation in RTD. Physicians agreed with overall process. PRACTICE IMPLICATIONS: Key factors for a successful RTD program is tailoring to institutional and individual needs.

Hyper-phosphorylation of Rb S249 together with CDK5R2/p39 overexpression are associated with impaired cell adhesion and epithelial-to-mesenchymal transition: Implications as a potential lung cancer grading and staging biomarker.

Prediction of lung cancer metastasis relies on post-resection assessment of tumor histology, which is a severe limitation since only a minority of lung cancer patients are diagnosed with resectable disease. Therefore, characterization of metastasis-predicting biomarkers in pre-resection small biopsy specimens is urgently needed. Here we report a biomarker consisting of the phosphorylation of the retinoblastoma protein (Rb) on serine 249 combined with elevated p39 expression. This biomarker correlates with epithelial-to-mesenchymal transition traits in non-small cell lung carcinoma (NSCLC) cells. Immunohistochemistry staining of NSCLC tumor microarrays showed that strong phospho-Rb S249 staining positively correlated with tumor grade specifically in the squamous cell carcinoma (SCC) subtype. Strong immunoreactivity for p39 positively correlated with tumor stage, lymph node invasion, and distant metastases, also in SCC. Linear regression analyses showed that the combined scoring for phospho-Rb S249, p39 and E-cadherin in SCC is even more accurate at predicting tumor staging, relative to each score individually. We propose that combined immunohistochemistry staining of NSCLC samples for Rb phosphorylation on S249, p39, and E-cadherin protein expression could aid in the assessment of tumor staging and metastatic potential when tested in small primary tumor biopsies. The intense staining for phospho-Rb S249 that we observed in high grade SCC could also aid in the precise sub-classification of poorly differentiated SCCs.

Somatic Mutations and Ancestry Markers in Hispanic Lung Cancer Patients.

INTRODUCTION: To address the lack of genomic data from Hispanic/Latino (H/L) patients with lung cancer, the Latino Lung Cancer Registry was established to collect patient data and biospecimens from H/L patients. METHODS: This retrospective observational study examined lung cancer tumor samples from 163 H/L patients, and tumor-derived DNA was subjected to targeted-exome sequencing (>1000 genes, including EGFR, KRAS, serine/threonine kinase 11 gene [STK11], and tumor protein p53 gene [TP53]) and ancestry analysis. Mutation frequencies in this H/L cohort were compared with those in a similar cohort of non-Hispanic white (NHW) patients and correlated with ancestry, sex, smoking status, and tumor histologic type. RESULTS: Of the adenocarcinomas in the H/L cohort (n = 120), 31% had EGFR mutations, versus 17% in the NHW control group (p < 0.001). KRAS (20% versus 38% [p = 0.002]) and STK11 (8% versus 16% [p = 0.065]) mutations occurred at lower frequency, and mutations in TP53 occurred at similar frequency (46% versus 40% [p = 0.355]) in H/L and NHW patients, respectively. Within the Hispanic cohort, ancestry influenced the rate of TP53 mutations (p = 0.009) and may have influenced the rate of EGFR, KRAS, and STK11 mutations. CONCLUSIONS: Driver mutations in H/L patients with lung adenocarcinoma differ in frequency from those in NHW patients associated with their indigenous American ancestry. The spectrum of driver mutations needs to be further assessed in the H/L population.

Differences in Smad4 expression in human papillomavirus type 16-positive and human papillomavirus type 16-negative head and neck squamous cell carcinoma.

The SMADs are a group of interrelated proteins that mediate transforming growth factor beta (TGF-beta) signaling. Upon TGF-beta binding the TGF-beta type I receptor phosphorylates Smad2 and Smad3, which then complex with Smad4 and translocate to the nucleus, with subsequent activation of target genes. Disruption of TGF-beta signaling is thought to contribute to the development of head and neck squamous cell carcinomas (HNSCC). Alterations in the function of the DPC4/Smad4 tumor suppressor gene have been found to inactivate TGF-beta signaling in several tumor types. For example, DPC4/Smad4 is lost or mutated in colorectal, pancreatic, and esophageal cancers. In addition, DPC4/Smad4 transcriptional activity and TGF-beta ability to inhibit DNA synthesis is blocked by the E7 protein of the human papillomavirus type 16 (HPV16) in cervical carcinoma cell lines. HPV16 infection is a risk factor for the development of a subset of HNSCC. This study was undertaken to investigate a potential correlation between expression of components of the TGF-beta signaling pathway and HPV16 status in HNSCC tumors. We examined the expression of TGF-beta signaling proteins Smad2, Smad2-P, and Smad4 by immunohistochemistry in 27 HPV16-negative and 16 HPV16-positive HNSCCs. We compared the expression patterns and assessed their relationship to HPV16 status. No significant differences were detected between HPV16-positive and HPV16-negative tumors in the expression of Smad2 and Smad2-P. Smad4 expression, however, was decreased in 56% of the HPV16-positive tumors and in 39% of HPV16-negative tumors. This difference was statistically significant (P = 0.01) suggesting that loss of Smad4 expression may be involved in HPV16-induced carcinogenesis of HNSCC.

Participation of both Gab1 and Gab2 in the activation of the ERK/MAPK pathway by epidermal growth factor.

Three members of Gab family docking proteins, Gab1, Gab2 and Gab3, have been identified in humans. Previous studies have found that the hepatocyte growth factor preferentially utilizes Gab1 for signalling, whereas Bcr-Abl selectively signals through Gab2. Gab1-SHP2 interaction has been shown to mediate ERK (extracellular-signal-regulated kinase) activation by EGF (epidermal growth factor). However, it was unclear whether EGF selectively utilizes Gab1 for signalling to ERK and whether Gab2 is dispensable in cells where Gab1 and Gab2 are co-expressed. Using T47D and MCF-7 human breast carcinoma cells that express endogenous Gab1 and Gab2, we examined the role of these docking proteins in EGF-induced ERK activation. It was found that EGF induced a similar amount of SHP2-Gab1 and SHP2-Gab2 complexes. Expression of either SHP2-binding defective Gab1 or Gab2 mutant blocked EGF-induced ERK activation. Down-regulation of either Gab1 or Gab2 by siRNAs (small interfering RNAs) effectively inhibited the EGF-stimulated ERK activation pathway and cell migration. Interestingly, the inhibitory effect of Gab1 siRNA could be rescued not only by expression of an exogenous mouse Gab1 but also by an exogenous human Gab2 and vice versa, but not by IRS1 (insulin receptor substrate 1). These results reveal that Gab2 plays a pivotal role in the EGF-induced ERK activation pathway and that it can complement the function of Gab1 in the EGF signalling pathway. Furthermore, Gab1 and Gab2 are critical signalling threshold proteins for ERK activation by EGF.