Challenges faced by physicians when discussing the Type 2 diabetes diagnosis with patients: insights from a cross-national study (IntroDia® )

AIMS

To investigate physicians' recalled experiences of their conversations with patients at diagnosis of Type 2 diabetes, because physician-patient communication at that time may influence the patient's subsequent self-care and outcomes.

METHODS

As part of a large cross-national study of physician-patient communication during early treatment of Type 2 diabetes (IntroDia^® ), we conducted a cross-sectional survey of physicians treating people with Type 2 diabetes in 26 countries across Africa, Asia, Europe, Latin America, the Middle East, North America and Oceania. The survey battery was designed to evaluate physician experiences during diagnosis conversations as well as physician empathy (measured using the Jefferson Scale of Physician Empathy).

RESULTS

A total of 6753 of 9247 eligible physicians completed the IntroDia^® survey (response rate 73.0%). Most respondents (87.5%) agreed that the conversation at diagnosis of Type 2 diabetes impacts the patient's acceptance of the condition and self-care. However, almost all physicians (98.9%) reported challenges during this conversation. Exploratory factor analysis revealed two related yet distinct types of challenges (r = 0.64, P < 0.0001) associated with either patients (eight challenges, α = 0.87) or the situation itself at diagnosis (four challenges, α = 0.72). There was a significant inverse association between physician empathy and overall challenge burden, as well as between empathy and each of the two types of challenges (all P < 0.0001). Study limitations include reliance on accurate physician recall and inability to assign causality to observed associations.

CONCLUSIONS

Globally, most physicians indicated that conversations with patients at diagnosis of Type 2 diabetes strongly influence patient self-care. Higher physician empathy was associated with fewer challenges during the diagnosis conversation.

Abstract 5019: HMGA1 amplifies Wnt signaling and expands the intestinal stem cell compartment to drive premalignant polyposis in transgenic mice

Emerging evidence suggests that cancer cells undergo chromatin remodeling and epigenetic reprogramming to co-opt stem cell properties and drive tumor progression. The HMGA1 chromatin remodeling protein is an architectural transcription factor that binds to DNA at AT-rich sequences where it “opens” chromatin, recruits transcriptional complexes, and modulates gene expression. The HMGA1 gene is highly expressed during embryogenesis and in adult stem cells, but silenced postnatally in differentiated tissues. HMGA1 becomes re-expressed in most high-grade cancers and high levels portend adverse clinical outcomes. In colon cancer, HMGA1 is among the genes most highly overexpressed compared to normal intestinal epithelium. We previously reported that HMGA1 drives tumor progression in colon cancer by inducing stem cell genes involved in an epithelial-mesenchymal transition. We also discovered that Hmga1 transgenic mice develop marked proliferative changes and pre-malignant polyposis in the intestinal epithelium. To determine how Hmga1 functions in the intestines during tissue homeostasis and carcinogenesis, we examined in transgenic mice and organoid models. Here, we uncover a novel role for Hmga1 in maintaining the intestinal stem cell (ISC) pool and Paneth cell niche. Hmga1 is required by ISCs to organize into three-dimensional organoids in vitro; silencing Hmga1 disrupts organoid formation and bud development. Conversely, overexpression of Hmga1 increases organoid formation, bud development, and replating efficiency, suggesting that Hmga1 enhances ISC function and/or number. We therefore crossed the Hmga1 transgenic mice onto the Lgr5-EGFP background to enumerate ISCs and found that Hmga1 expands the ISC compartment. To determine how this occurs, we performed in vivo imaging and discovered that Hmga1 enhances self-renewal of ISCs. Mechanistically, we found that Hmga1 amplifies Wnt/β-catenin signaling by inducing genes encoding both Wnt agonist receptors and downstream Wnt target genes. Surprisingly, Hmga1 also expands the Paneth cell niche, which is comprised of terminally differentiated crypt cells that secrete Wnt to support ISCs. Because Paneth cells require Sox9 for development, we determined whether Hmga1 regulates its expression. Hmga1 binds directly to the Sox9 promoter at 2 AT-rich sites to activate its expression. In human colonic epithelium, HMGA1 and SOX9 are positively correlated, and both become markedly up-regulated in colon carcinogenesis. This work not only provides new insights into the role of Hmga1 in intestinal homeostasis by maintaining both the stem cell pool and epithelial niche compartment, but also suggests that deregulated Hmga1 perturbs this equilibrium during polyposis and carcinogenesis. Our results also highlight the HMGA1-WNT-SOX9 pathway as rational therapeutic target in colon carcinogenesis.

Citation Format: Lingling Xian, Dan Georgess, Li Luo, Lionel Chia, Qihua Gu, Tait Huso, Amy Belton, David Huso, Andrew Ewald, Linda M.S. Resar. HMGA1 amplifies Wnt signaling and expands the intestinal stem cell compartment to drive premalignant polyposis in transgenic mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5019. doi:10.1158/1538-7445.AM2017-5019

HMGA1 amplifies Wnt signalling and expands the intestinal stem cell compartment and Paneth cell niche

High-mobility group A1 (Hmga1) chromatin remodelling proteins are enriched in intestinal stem cells (ISCs), although their function in this setting was unknown. Prior studies showed that Hmga1 drives hyperproliferation, aberrant crypt formation and polyposis in transgenic mice. Here we demonstrate that Hmga1 amplifies Wnt/β-catenin signalling to enhance self-renewal and expand the ISC compartment. Hmga1 upregulates genes encoding both Wnt agonist receptors and downstream Wnt effectors. Hmga1 also helps to 'build' an ISC niche by expanding the Paneth cell compartment and directly inducing Sox9, which is required for Paneth cell differentiation. In human intestine, HMGA1 and SOX9 are positively correlated, and both become upregulated in colorectal cancer. Our results define a unique role for Hmga1 in intestinal homeostasis by maintaining the stem cell pool and fostering terminal differentiation to establish an epithelial stem cell niche. This work also suggests that deregulated Hmga1 perturbs this equilibrium during intestinal carcinogenesis.

Abstract 1704: High mobility group A1 chromatin remodeling protein expands the intestinal stem cell compartment and Paneth cell niche through Wnt/β-catenin signaling and Sox9

The High Mobility Group A1 (HMGA1) gene is overexpressed in most poorly differentiated cancers and high levels portend adverse clinical outcomes, although the molecular mechanisms through which it functions are poorly understood. HMGA1 encodes the HMGA1a and HMGA1b chromatin remodeling proteins, which modulate gene expression by bending chromatin and orchestrating the assembly of transcription factor complexes to DNA. HMGA1 is highly expressed during embryogenesis, but silenced in adult, differentiated tissues. Postnatally, HMGA1 expression is maintained in adult stem cells, such as intestinal stem cells (ISCs); however, its role in this setting has been unknown. Here, we report that Hmga1 overexpression in ISCs of transgenic mice drives expansion in the ISC compartment leading to hyperproliferation, aberrant crypt formation, and polyposis. Surprisingly, Hmga1 transgenic mice also exhibit marked expansion in terminally differentiated Paneth cells, which comprise an epithelial cell niche for ISCs. To dissect the mechanisms mediating these phenotypes, we generated three-dimensional (3D) intestinal organoids with varied expression of Hmga1. Strikingly, silencing Hmga1 in wildtype crypt cells disrupts their ability to organize into functional 3D organoids with bud formation, while crypt cells expressing ectopic Hmga1 exhibit enhanced organoid formation with increased ISC number, proliferation, and bud development. Because Wnt/β-catenin signaling is central to ISC function, we determined whether Hmga1 modulates this pathway. β-catenin protein is increased in the crypts of the Hmga1 transgenic mice and organoids. Hmga1 amplifies Wnt/β-catenin signaling by inducing both genes that encode Wnt cell surface receptors and target genes downstream of Wnt/β-catenin. Hmga1 also directly up-regulates Sox9, which is required for terminal differentiation to Paneth cells. This is the first example of Hmga1 fostering terminal differentiation to establish a stem cell niche. In human intestinal epithelium, HMGA1 and SOX9 are highly correlated (P = 0.008), and both become up-regulated in carcinogenesis. These results reveal a novel role for Hmga1 in intestinal homeostasis by maintaining both the stem cell pool and epithelial niche compartment and suggest that deregulated Hmga1 perturbs this equilibrium during intestinal carcinogenesis.

Citation Format: Lingling Xian, Tait Huso, Amy Belton, David Huso, Linda M. S. Resar. High mobility group A1 chromatin remodeling protein expands the intestinal stem cell compartment and Paneth cell niche through Wnt/β-catenin signaling and Sox9. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1704.

HMGA1: a master regulator of tumor progression in triple-negative breast cancer cells

Emerging evidence suggests that tumor cells metastasize by co-opting stem cell transcriptional networks, although the molecular underpinnings of this process are poorly understood. Here, we show for the first time that the high mobility group A1 (HMGA1) gene drives metastatic progression in triple negative breast cancer cells (MDA-MB-231, Hs578T) by reprogramming cancer cells to a stem-like state. Silencing HMGA1 expression in invasive, aggressive breast cancer cells dramatically halts cell growth and results in striking morphologic changes from mesenchymal-like, spindle-shaped cells to cuboidal, epithelial-like cells. Mesenchymal genes (Vimentin, Snail) are repressed, while E-cadherin is induced in the knock-down cells. Silencing HMGA1 also blocks oncogenic properties, including proliferation, migration, invasion, and orthotopic tumorigenesis. Metastatic progression following mammary implantation is almost completely abrogated in the HMGA1 knock-down cells. Moreover, silencing HMGA1 inhibits the stem cell property of three-dimensional mammosphere formation, including primary, secondary, and tertiary spheres. In addition, knock-down of HMGA1 depletes cancer initiator/cancer stem cells and prevents tumorigenesis at limiting dilutions. We also discovered an HMGA1 signature in triple negative breast cancer cells that is highly enriched in embryonic stem cells. Together, these findings indicate that HMGA1 is a master regulator of tumor progression in breast cancer by reprogramming cancer cells through stem cell transcriptional networks. Future studies are needed to determine how to target HMGA1 in therapy.

Abstract 3122: HMGA1 reprograms breast cancer cells by inducing transcriptional networks involved in an epithelial-mesenchymal transition, stemness, and metastatic progression

Despite advances in our ability to detect and treat breast cancer, it remains a leading cause of death in women with cancer worldwide, and the incidence is rising. Approximately 15-20% of all cases are classified as triple negative breast cancer (TNBC), a subtype that is frequently associated with rapid progression and poor outcome. TNBC refers to the lack of detectable markers for the estrogen receptor (ER), progesterone receptor (PR), and Her2/neu amplification. These tumors do not respond to our most effective and least toxic therapies, including hormonal therapy (tamoxifen) or trastuzumab. We are studying molecular pathways that lead to tumor progression in TNBC and can be targeted with novel therapies. Our focus is the high mobility group A1 (HMGA1) oncogene. HMGA1 is highly expressed during embryogenesis, with low or undetectable levels in differentiated, adult tissues. HMGA1 is enriched in virtually all high-grade (poorly differentiated) cancers studied to date, including TNBCs, and high expression portends a poor prognosis in breast and other cancers. To investigate the role of HMGA1 in tumor progression in breast cancer, we silenced HMGA1 expression in TNBC cell lines (MDA-MB-231, Hs578T) using lentiviral-mediated delivery of short hairpin RNA. Strikingly, proliferation was markedly impaired, and many cells underwent apoptotic cell death within 5 days following HMGA1 knock-down. Surprisingly, cell morphology also changed dramatically, whereby the fibroblast-like, spindle-shaped cells became cuboidal and epithelial-like, consistent with a mesenchymal-epithelial transition, or MET. E-CADHERIN mRNA was induced, while both SNAIL and VIMENTIN were repressed in the knock-down cells, also consistent with MET. In addition, silencing HMGA1 blocked migration, invasion, and the formation of tumor foci in the lungs following tail vein injection of MDA-MB-231 cells. Moreover, both primary tumorigenesis and metastatic progression to the lungs were markedly inhibited in MDA-MB-231 cells with knock-down of HMGA1 following implantation in mammary fat pads. Furthermore, silencing HMGA1 blocked primary and secondary mammosphere formation, indicating that HMGA1 is required for this stem cell property. Tumorigenesis experiments at limiting dilutions showed that silencing HMGA1 depletes the tumor initiator/cancer stem cell pool. Using global gene expression analysis, we identified an HMGA1 signature of differentially-regulated genes in the control cells compared to knock-down cells. We also found that the HMGA1 signature is highly enriched in embryonic stem cells. Together, these findings indicate that silencing HMGA1 reprograms invasive, mesenchymal TNBCs into non-invasive, epithelial-like cells with slower growth and an altered gene expression signature. Studies are now needed to determine how to target HMGA1 in therapy.

Citation Format: Sandeep N. Shah, Leslie Cope, Amy Belton, Weijie Poh, Saraswati Sukumar, David Huso, Linda Resar. HMGA1 reprograms breast cancer cells by inducing transcriptional networks involved in an epithelial-mesenchymal transition, stemness, and metastatic progression. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3122. doi:10.1158/1538-7445.AM2013-3122

HMGA1 reprograms somatic cells into pluripotent stem cells by inducing stem cell transcriptional networks

BACKGROUND

Although recent studies have identified genes expressed in human embryonic stem cells (hESCs) that induce pluripotency, the molecular underpinnings of normal stem cell function remain poorly understood. The high mobility group A1 (HMGA1) gene is highly expressed in hESCs and poorly differentiated, stem-like cancers; however, its role in these settings has been unclear.

METHODS/PRINCIPAL FINDINGS

We show that HMGA1 is highly expressed in fully reprogrammed iPSCs and hESCs, with intermediate levels in ECCs and low levels in fibroblasts. When hESCs are induced to differentiate, HMGA1 decreases and parallels that of other pluripotency factors. Conversely, forced expression of HMGA1 blocks differentiation of hESCs. We also discovered that HMGA1 enhances cellular reprogramming of somatic cells to iPSCs together with the Yamanaka factors (OCT4, SOX2, KLF4, cMYC - OSKM). HMGA1 increases the number and size of iPSC colonies compared to OSKM controls. Surprisingly, there was normal differentiation in vitro and benign teratoma formation in vivo of the HMGA1-derived iPSCs. During the reprogramming process, HMGA1 induces the expression of pluripotency genes, including SOX2, LIN28, and cMYC, while knockdown of HMGA1 in hESCs results in the repression of these genes. Chromatin immunoprecipitation shows that HMGA1 binds to the promoters of these pluripotency genes in vivo. In addition, interfering with HMGA1 function using a short hairpin RNA or a dominant-negative construct blocks cellular reprogramming to a pluripotent state.

CONCLUSIONS

Our findings demonstrate for the first time that HMGA1 enhances cellular reprogramming from a somatic cell to a fully pluripotent stem cell. These findings identify a novel role for HMGA1 as a key regulator of the stem cell state by inducing transcriptional networks that drive pluripotency. Although further studies are needed, these HMGA1 pathways could be exploited in regenerative medicine or as novel therapeutic targets for poorly differentiated, stem-like cancers.

The HMGA1-COX-2 axis: a key molecular pathway and potential target in pancreatic adenocarcinoma

CONTEXT

Although pancreatic cancer is a common, highly lethal malignancy, the molecular events that enable precursor lesions to become invasive carcinoma remain unclear. We previously reported that the high-mobility group A1 (HMGA1) protein is overexpressed in >90% of primary pancreatic cancers, with absent or low levels in early precursor lesions.

METHODS

Here, we investigate the role of HMGA1 in reprogramming pancreatic epithelium into invasive cancer cells. We assessed oncogenic properties induced by HMGA1 in non-transformed pancreatic epithelial cells expressing activated K-RAS. We also explored the HMGA1-cyclooxygenase (COX-2) pathway in human pancreatic cancer cells and the therapeutic effects of COX-2 inhibitors in xenograft tumorigenesis.

RESULTS

HMGA1 cooperates with activated K-RAS to induce migration, invasion, and anchorage-independent cell growth in a cell line derived from normal human pancreatic epithelium. Moreover, HMGA1 and COX-2 expression are positively correlated in pancreatic cancer cell lines (r(2) = 0.93; p < 0.001). HMGA1 binds directly to the COX-2 promoter at an AT-rich region in vivo in three pancreatic cancer cell lines. In addition, HMGA1 induces COX-2 expression in pancreatic epithelial cells, while knock-down of HMGA1 results in repression of COX-2 in pancreatic cancer cells. Strikingly, we also discovered that Sulindac (a COX-1/COX-2 inhibitor) or Celecoxib (a more specific COX-2 inhibitor) block xenograft tumorigenesis from pancreatic cancer cells expressing high levels of HMGA1.

CONCLUSIONS

Our studies identify for the first time an important role for the HMGA1-COX-2 pathway in pancreatic cancer and suggest that targeting this pathway could be effective to treat, or even prevent, pancreatic cancer.

Abstract 429: The high mobility group A1 oncogene enhances cellular reprogramming to a pluripotent stem-like cell

The molecular mechanisms that enable cancer cells to metastasize are poorly understood, although emerging evidence indicates that transcriptional networks required for stem cell properties during embryogenesis are co-opted by cancer cells during metastatic progression. To elucidate the molecular underpinnings of “stemness” in cancer and normal development, we investigated transcriptional networks and epigenetic alterations during the induction of pluripotent stem cells. Our focus is the high mobility group A1 (HMGA1) gene, which encodes proteins that bind to AT-rich regions of DNA and orchestrate the assembly of transcription factor complexes to alter chromatin structure and modulate gene expression. Our group first discovered that HMGA1 functions as a potent oncogene in cultured cells and causes aggressive tumors in transgenic mice. Recent studies also identified HMGA1 as a key transcription factor enriched in human embryonic stem (hESCs) cells, induced pluripotent stem cells (iPSCs), refractory leukemia, and high-grade/poorly differentiated cancers arising from diverse tissues. Together, these findings are consistent with the hypothesis that HMGA1 drives an undifferentiated, stem cell-like state during malignant transformation and normal development. To further investigate the role of HMGA1 in the stem cell state, we assessed its function in the derivation of iPSCs using multiple approaches. Here, we demonstrate for the first time that HMGA1 significantly enhances the reprogramming of somatic cells (bone marrow-derived mesenchymal stem cells, fetal lung cells, or mononuclear blood cells) into iPSCs together with OCT4, SOX2, KLF4, and cMYC (OSKM) using a retroviral or episomal, non-integrating approach. When hESCs are induced to differentiate, HMGA1 expression falls and parallels that of other pluripotency factors, such as OCT4, NANOG, and SOX2. We also found that forced expression of HMGA1 blocks differentiation of hESCs. To determine how HMGA1 induces a stem cell state, we assessed gene expression and epigenetic changes. During the reprogramming process, HMGA1 induces the expression of pluripotency and cancer genes, including SOX2, LIN28, and cMYC, while in hESCs, knock-down of HMGA1 results in repression of these genes. In addition, NANOG and OCT4 are repressed in hESCs following knock-down of HMGA1. By chromatin immunoprecipitation, HMGA1 binds to the promoters of SOX2, LIN28, and cMYC in vivo in hESCs. Moreover, HMGA1 is associated with decreased promoter methylation of select stem cell genes early in reprogramming. These findings uncover a key role for HMGA1 as a regulator of the stem cell state through transcriptional networks and epigenetic remodeling that induce pluripotency and an undifferentiated state. Further studies are needed to determine if HMGA1 pathways could be targeted in poorly differentiated, stem-like cancers or exploited in regenerative medicine.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 429. doi:1538-7445.AM2012-429

HMGA1 induces intestinal polyposis in transgenic mice and drives tumor progression and stem cell properties in colon cancer cells

BACKGROUND

Although metastatic colon cancer is a leading cause of cancer death worldwide, the molecular mechanisms that enable colon cancer cells to metastasize remain unclear. Emerging evidence suggests that metastatic cells develop by usurping transcriptional networks from embryonic stem (ES) cells to facilitate an epithelial-mesenchymal transition (EMT), invasion, and metastatic progression. Previous studies identified HMGA1 as a key transcription factor enriched in ES cells, colon cancer, and other aggressive tumors, although its role in these settings is poorly understood.

METHODS/PRINCIPAL FINDINGS

To determine how HMGA1 functions in metastatic colon cancer, we manipulated HMGA1 expression in transgenic mice and colon cancer cells. We discovered that HMGA1 drives proliferative changes, aberrant crypt formation, and intestinal polyposis in transgenic mice. In colon cancer cell lines from poorly differentiated, metastatic tumors, knock-down of HMGA1 blocks anchorage-independent cell growth, migration, invasion, xenograft tumorigenesis and three-dimensional colonosphere formation. Inhibiting HMGA1 expression blocks tumorigenesis at limiting dilutions, consistent with depletion of tumor-initiator cells in the knock-down cells. Knock-down of HMGA1 also inhibits metastatic progression to the liver in vivo. In metastatic colon cancer cells, HMGA1 induces expression of Twist1, a gene involved in embryogenesis, EMT, and tumor progression, while HMGA1 represses E-cadherin, a gene that is down-regulated during EMT and metastatic progression. In addition, HMGA1 is among the most enriched genes in colon cancer compared to normal mucosa.

CONCLUSIONS

Our findings demonstrate for the first time that HMGA1 drives proliferative changes and polyp formation in the intestines of transgenic mice and induces metastatic progression and stem-like properties in colon cancer cells. These findings indicate that HMGA1 is a key regulator, both in metastatic progression and in the maintenance of a stem-like state. Our results also suggest that HMGA1 or downstream pathways could be rational therapeutic targets in metastatic, poorly differentiated colon cancer.

HMGA1 drives stem cell, inflammatory pathway, and cell cycle progression genes during lymphoid tumorigenesis

BACKGROUND

Although the high mobility group A1 (HMGA1) gene is widely overexpressed in diverse cancers and portends a poor prognosis in some tumors, the molecular mechanisms that mediate its role in transformation have remained elusive. HMGA1 functions as a potent oncogene in cultured cells and induces aggressive lymphoid tumors in transgenic mice. Because HMGA1 chromatin remodeling proteins regulate transcription, HMGA1 is thought to drive malignant transformation by modulating expression of specific genes. Genome-wide studies to define HMGA1 transcriptional networks during tumorigenesis, however, are lacking. To define the HMGA1 transcriptome, we analyzed gene expression profiles in lymphoid cells from HMGA1a transgenic mice at different stages in tumorigenesis.

RESULTS

RNA from lymphoid samples at 2 months (before tumors develop) and 12 months (after tumors are well-established) was screened for differential expression of > 20,000 unique genes by microarray analysis (Affymetrix) using a parametric and nonparametric approach. Differential expression was confirmed by quantitative RT-PCR in a subset of genes. Differentially expressed genes were analyzed for cellular pathways and functions using Ingenuity Pathway Analysis. Early in tumorigenesis, HMGA1 induced inflammatory pathways with NFkappaB identified as a major node. In established tumors, HMGA1 induced pathways involved in cell cycle progression, cell-mediated immune response, and cancer. At both stages in tumorigenesis, HMGA1 induced pathways involved in cellular development, hematopoiesis, and hematologic development. Gene set enrichment analysis showed that stem cell and immature T cell genes are enriched in the established tumors. To determine if these results are relevant to human tumors, we knocked-down HMGA1 in human T-cell leukemia cells and identified a subset of genes dysregulated in both the transgenic and human lymphoid tumors.

CONCLUSIONS

We found that HMGA1 induces inflammatory pathways early in lymphoid tumorigenesis and pathways involved in stem cells, cell cycle progression, and cancer in established tumors. HMGA1 also dyregulates genes and pathways involved in stem cells, cellular development and hematopoiesis at both early and late stages of tumorigenesis. These results provide insight into HMGA1 function during tumor development and point to cellular pathways that could serve as therapeutic targets in lymphoid and other human cancers with aberrant HMGA1 expression.

SOD2, the principal scavenger of mitochondrial superoxide, is dispensable for embryogenesis and imaginal tissue development but essential for adult survival

Definitive evidence on the impact of MnSOD/SOD2-deficiency and the consequent effects of high flux of mitochondrial reactive oxygen species (ROS) on pre-natal/pre-adult development has yet to be reported for either Drosophila or mice. Here we report that oocytes lacking maternal SOD2 protein develop into adults just like normal SOD2-containing oocytes suggesting that maternal SOD2-mediated protection against mitochondrial ROS is not essential for oocyte viability. However, the capacity of SOD2-null larvae to undergo successful metamorphosis into adults is negatively influenced in the absence of SOD2. We therefore determined the impact of a high superoxide environment on cell size, progression through the cell cycle, cell differentiation, and cell death and found no difference between SOD2-null and SOD2+ larva and pupa. Thus loss of SOD2 activity clearly has no effect on pre-adult imaginal tissues. Instead, we found that the high mitochondrial superoxide environment arising from the absence of SOD2 leads to the induction of autophagy. Such autophagic response may underpin the resistance of pre-adult tissues to unscavenged ROS. Finally, while our data establish that SOD2 activity is less essential for normal development, the mortality of Sod2-/- neonates of both Drosophila and mice suggests that SOD2 activity is indeed essential for the viability of adults. We therefore asked if the early mortality of SOD2-null young adults could be rescued by activation of SOD2 expression. The results support the conclusion that the early mortality of SOD2-null adults is largely attributable to the absence of SOD2 activity in the adult per se. This finding somewhat contradicts the widely held notion that failure to scavenge the high volume of superoxide emanating from the oxidative demands of development would be highly detrimental to developing tissues.

Upregulation of MMP-2 by HMGA1 promotes transformation in undifferentiated, large-cell lung cancer

Although lung cancer is the leading cause of cancer death worldwide, the precise molecular mechanisms that give rise to lung cancer are incompletely understood. Here, we show that HMGA1 is an important oncogene that drives transformation in undifferentiated, large-cell carcinoma. First, we show that the HMGA1 gene is overexpressed in lung cancer cell lines and primary human lung tumors. Forced overexpression of HMGA1 induces a transformed phenotype with anchorage-independent cell growth in cultured lung cells derived from normal tissue. Conversely, inhibiting HMGA1 expression blocks anchorage-independent cell growth in the H1299 metastatic, undifferentiated, large-cell human lung carcinoma cells. We also show that the matrix metalloproteinase-2 (MMP-2) gene is a downstream target upregulated by HMGA1 in large-cell carcinoma cells. In chromatin immunoprecipitation experiments, HMGA1 binds directly to the MMP-2 promoter in vivo in large-cell lung cancer cells, but not in squamous cell carcinoma cells. In large-cell carcinoma cell lines, there is a significant, positive correlation between HMGA1 and MMP-2 mRNA. Moreover, interfering with MMP-2 expression blocks anchorage-independent cell growth in H1299 large-cell carcinoma cells, indicating that the HMGA1-MMP-2 pathway is required for this transformation phenotype in these cells. Blocking MMP-2 expression also inhibits migration and invasion in the H1299 large-cell carcinoma cells. Our findings suggest an important role for MMP-2 in transformation mediated by HMGA1 in large-cell, undifferentiated lung carcinoma and support the development of strategies to target this pathway in selected tumors.

The high-mobility group A1a/signal transducer and activator of transcription-3 axis: an achilles heel for hematopoietic malignancies?

Although HMGA1 (high-mobility group A1; formerly HMG-I/Y) is an oncogene that is widely overexpressed in aggressive cancers, the molecular mechanisms underlying transformation by HMGA1 are only beginning to emerge. HMGA1 encodes the HMGA1a and HMGA1b protein isoforms, which function in regulating gene expression. To determine how HMGA1 leads to neoplastic transformation, we looked for genes regulated by HMGA1 using gene expression profile analysis. Here, we show that the STAT3 gene, which encodes the signaling molecule signal transducer and activator of transcription 3 (STAT3), is a critical downstream target of HMGA1a. STAT3 mRNA and protein are up-regulated in fibroblasts overexpressing HMGA1a and activated STAT3 recapitulates the transforming activity of HMGA1a in fibroblasts. HMGA1a also binds directly to a conserved region of the STAT3 promoter in vivo in human leukemia cells by chromatin immunoprecipitation and activates transcription of the STAT3 promoter in transfection experiments. To determine if this pathway contributes to HMGA1-mediated transformation, we investigated STAT3 expression in our HMGA1a transgenic mice, all of which developed aggressive lymphoid malignancy. STAT3 expression was increased in the leukemia cells from our transgenics but not in control cells. Blocking STAT3 function induced apoptosis in the transgenic leukemia cells but not in controls. In primary human leukemia samples, there was a positive correlation between HMGA1a and STAT3 mRNA. Moreover, blocking STAT3 function in human leukemia or lymphoma cells led to decreased cellular motility and foci formation. Our results show that the HMGA1a-STAT3 axis is a potential Achilles heel that could be exploited therapeutically in hematopoietic and other malignancies overexpressing HMGA1a.

Deletions encompassing the manganese superoxide dismutase gene in the Drosophila melanogaster genome

Two deletions, Df(2R)Sod2-11 and Df(2R)Sod2-332, are recovered that encompass the manganese superoxide dismutase (MnSOD) gene or a null mutant referred to as SOD2n283 in Drosophila. Molecular analysis has revealed that the Df(2R)Sod2-332 deletion completely uncovered both MnSOD and its adjacent gene, Arp53D, whereas Df(2R)Sod2-11 was missing the promoter region of MnSOD gene. As a consequence of reduced MnSOD expression, these deletion heterozygotes are now sensitive to oxidative stress. Complementation analysis with some recently recovered deletions in the 53C/D region has established that other essential loci exist in this interval, and second, that Arp53D function is not essential for the survival of the organism. These deletions will be instrumental in the recovery of missense substitutions in the MnSOD peptide and their influence on oxidative stress resistance.

ASod2Null Mutation Confers Severely Reduced Adult Life Span in Drosophila

A null mutation for the Sod2 gene, Sod2n283, was obtained in Drosophila melanogaster. Homozygous Sod2 null (Sodn283/Sodn283) adult flies survive up to 24 hr following eclosion, a phenotype reminiscent of mice, where Sod2–/– progeny suffer neonatal lethality. Sodn283/+ heterozygotes are sensitive to oxidative stress induced by paraquat treatment.

Gestational diabetes mellitus: a syndrome with phenotypic and genotypic heterogeneity

One hundred ninety-nine gravida with gestational diabetes mellitus (GDM) defined as "carbohydrate intolerance of varying severity with onset or first recognition during pregnancy" have been stratified into subgroups on the basis of fasting plasma glucose and evaluated for further phenotypic and genotypic heterogeneity. A significantly greater proportion of the women in all our groups were older and heavier than in a "control" population of 148 consecutive gravida with documented normal oral glucose tolerance. After correction for age and weight by covariate analysis, absolute insulinopenia in response to oral glucose could be demonstrated in all GDM groups, although exceptions were present in each. The incidence of diabetes in the mothers of our patients with GDM was 8-fold greater than in controls; the incidence in fathers did not deviate from control patterns. HLA-DR3 and DR4 antigens were more frequently present in GDM and the increase was statistically significant in blacks. At the time of diagnosis, cytoplasmic islet cell antibodies (ICA) were significantly more common in GDM associated with elevated fasting plasma glucose than in controls; the frequency of ICA was 18.4% (7/38) in women with fasting plasma glucose greater than or equal to 130 mg/dl. Our findings indicate that GDM entails genotypic as well as phenotypic diversity and may include patients with slowly-evolving Type I diabetes mellitus, as well as patients with Type II diabetes mellitus, and women with asymptomatic diabetes which antedated the pregnancy (i.e. pregestational diabetes mellitus). Appreciation of this heterogeneity should be incorporated into any evaluation of intervention strategies for women with GDM or into prognoses concerning their postpartum metabolic status.

Gestational diabetes mellitus. Heterogeneity of maternal age, weight, insulin secretion, HLA antigens, and islet cell antibodies and the impact of maternal metabolism on pancreatic B-cell and somatic development in the offspring

We have examined gravida with gestational diabetes mellitus (GDM), as defined by the National Diabetes Data Group (Diabetes 1979; 28:1039), for phenotypic and genotypic heterogeneity. Fasting plasma glucose (FPG) at diagnosis was used for further stratification of GDM according to putative metabolic severity into class A1 (FPG less than 105 mg/dl [N = 129]), class A2 (FPG 105-129 mg/dl [N = 47]), and class B1 (FPG greater than or equal to 130 mg/dl [N = 23]). All GDM classes tended to be older and heavier than consecutive gravida with documented normal glucose tolerance (controls, N = 148). Subdivision into "lean" and "obese" indicated that plasma immunoreactive insulin (IRI) was greater after overnight fast in the obese of all groups except B1. However, absolute increases in IRI above fasting levels in response to glucose during OGTT were significantly enhanced by obesity only in class A2 gravida. Adjustment for the effects of age and weight by covariate analysis indicated that the IRI response to glycemic stimulation is usually attenuated in all forms of GDM. Mean values for increases in IRI above fasting values during the first 15 min and IRI increments relative to the increases in plasma glucose throughout the 180-min OGTT were below control values in all GDM groups and progressively so, i.e., A1 less than A2 less than B1. The absolute insulinopenia was not invariable; a small number of gravida from all GDM groups displayed well-preserved IRI responses to oral glucose. Genotypic evaluation of the GDM population disclosed an increased occurrence of "markers" known to be associated with type I diabetes mellitus.(ABSTRACT TRUNCATED AT 250 WORDS)

A method of assessment during vocational training: report of a pilot study

Problems arising from the present rate of failure of vocational trainees in the MRCGP examination are outlined; and the role of formative assessment during training in reducing this rate is considered. A study is described in which trainees in a number of centres were assessed by a method designed to measure specified cognitive abilities and areas of knowledge. The method, based on written papers, provides each candidate with a profile of performance and generates comparative standards. Reliability of marking, the distribution of candidate-scores within and between areas of assessment and techniques for monitoring the effectiveness of questions are reported. Use of the method by College as an educational service to trainees is considered, along with its potential as a Part I MRCGP examination.