Phenotype and Variant Spectrum in the LAMB3 Form of Amelogenesis Imperfecta

Amelogenesis imperfecta (AI) is a heterogeneous group of inherited disorders characterized by abnormal formation of dental enamel, either in isolation or as part of a syndrome. Heterozygous variants in laminin subunit beta 3 ( LAMB3) cause AI with dominant inheritance in the absence of other cosegregating clinical features. In contrast, biallelic loss-of-function variants in LAMB3 cause recessive junctional epidermolysis bullosa, characterized by life-threatening skin fragility. We identified 2 families segregating autosomal dominant AI with variable degrees of a distinctive hypoplastic phenotype due to pathogenic variants in LAMB3. Whole exome sequencing revealed a nonsense variant (c.3340G>T, p.E1114*) within the final exon in family 1, while Sanger sequencing in family 2 revealed a variant (c.3383-1G>A) in the canonical splice acceptor site of the final exon. Analysis of cDNA from family 2 revealed retention of the final intron leading to a premature termination codon. Two unerupted third molar teeth from individual IV:5 in family 2 were subject to computerized tomography and scanning electron microscopy. LAMB3 molar teeth have a multitude of cusps versus matched controls. LAMB3 enamel was well mineralized but pitted. The architecture of the initially secreted enamel was abnormal, with cervical enamel appearing much less severely affected than coronal enamel. This study further defines the variations in phenotype-genotype correlation for AI due to variants in LAMB3, underlines the clustering of nonsense and frameshift variants causing AI in the absence of junctional epidermolysis bullosa, and highlights the shared AI phenotype arising from variants in genes coding for hemidesmosome proteins.

Abstract P6-12-13: Single domain antibody (SBT-100) inhibits growth of human HER2+ and triple negative breast cancers (TNBC) in xenografts by binding STAT3 and P-STAT3

SBT-100 is a single domain antibody (sdAb), developed by Singh Biotechnology, that binds unphosphorylated signal transducer and activator of transcription 3 (STAT3) and phosphorylated STAT3 (P-STAT3). SBT-100 is approximately 13 kD or less than 1/10th the size of a human IgG molecule, and is able to cross the cell membrane to bind intracellular STAT3 and P-STAT3. This in turn inhibits its effects on genes that promote malignant behavior of cancer cells. SBT-100 has a short serum half-life but a long biological half-life. Since certain types of human breast cancers express P-STAT3, we wanted to determine if SBT-100 could inhibit the growth of human breast cancers in vitro and in vivo by studying its effects on MCF-7 (ER+/PR+), BT474 (HER2+), and MDA-MB-231 (TNBC) cells.

BACKGROUND: Many different types of human cancers (solid tumors, leukemias, and lymphomas) are dependent on constitutive expression of (P-STAT3) for their malignant phenotype. Growth factors, tyrosine kinase receptors, cytokines (IL-6, IL-11, IL-12, IL-23), BCR-ABL, and Src are some ways that STAT3 can be activated. In turn P-STAT3 turns on genes such as Cyclin D1 & D3, MMPs, Bcl-xL, Mcl-1, survivin, VEGF, and HIF-1 alpha. Constitutive expression of P-STAT3 has been shown to promote cancer cell proliferation, survival, angiogenesis, immune suppression, and metastasis. Additionally there is increasing evidence suggesting that unphosphorylated STAT3 contributes to malignant phenotype of cancers. STAT3 is also important for the survival of cancer stem cells as well as for some human breast cancers.

METHODS: Immunoprecipitation and Western blot analyses were carried out to test whether SBT-100 binds cytoplasmic STAT3 and P-STAT3 in various malignant cell lines (e.g., MDA-MB-231, PANC-1, DU145, and HeLa). MTT assays were done to determine if SBT-100 could suppress the growth of different types of human breast cancers in vitro. Xenograft cancer models using ER+/PR+ (MCF-7), HER2+ (BT474), and TNBC (MDA-MB-231) cancer cells were used to evaluate treatment with SBT-100 1mg/kg/BID (IV and/or IP route).

RESULTS: Immunoprecipitation and Western blot studies demonstrated that SBT-100 binds to both STAT3 and P-STAT3 in human cancers cells (MDA-MB-231, PANC-1, DU145, and HeLa). In a three day MTT assay, at least 90% growth suppression was achieved for all three subtypes of human breast cancer, which is highly significant. In the xenograft cancer models, SBT-100 (1mg/kg/BID) treatment for 28 days, yield growth suppression as follows: MDA-MB-231 44.8% (p<0.05) versus its control group and BT474 52% (p<0.07). While the MCF-7 xenograft cancer model showed no suppression.

CONCLUSION: Singh Biotechnology's novel sdAb, SBT-100 suppresses growth of TNBC and HER2+ human breast cancers in vivo and suppresses growth of ER+/PR+, HER2+, and TNBC cells in vitro. The most significant anti-cancer effects of SBT-100 is observed against human TNBC.

Citation Format: Singh S, Murillo G, Chen D, Singh A, Singh S, Singh A, Mehta R, Parihar A. Single domain antibody (SBT-100) inhibits growth of human HER2+ and triple negative breast cancers (TNBC) in xenografts by binding STAT3 and P-STAT3 [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-12-13.

P2-17-05: Antiprogestin Proellex Suppresses Proliferation of Aromatase Overexpressing and Letrozole Resistant T47D Breast Cancer Cells

Background: Aromatase is a cytochrome P450 CYP19A1 enzyme responsible for the conversion of C19 androgens to C18 estrogen. Aromatase overexpression leads to increase in local estrogen concentration in post menopausal women diagnosed for breast cancer. Aromatase inhibitors (AI) are used as one of the first line therapies for the treatment of ER+PR+ breast cancers. However, many patients acquire resistance to AI treatment. Therefore alternative approaches are being sought for patients with AI resistance. Previous reports suggest that upregulation of progesterone receptor can lead to enhanced expression of EGFR/ERK/MAPK involved in acquiring resistance. In this study, we evaluated the effect of a selective progesterone receptor modulator, CDB4124 (Proellex) with low glucocorticoid activity on aromatase overexpressing and Letrozole resistant T47D cells.

Methods: Aromatase overexpressing T47D (T47Darom) and respective control (T47Dcon) breast cancer cell lines were generated by stable transfection with plasmid containing CYP19A1 coding region, or empty vector respectively. Letrozole resistant cell line (T47DaromLR) was generated by incubating T47Darom for 75 weeks in the presence of 10μM Letrozole. Cell proliferation was determined by MTT or Crystal violet assays. Gene expressions were quantitated by qRT-PCR whereas proteins were identified by western blot analyses, flow cytometry and immunofluorescence staining. Aromatase activity was determined by estradiol ELISA. The effects of Proellex on anchorage independent growth were measured by soft agar colony formation. Statistical differences between the various groups were determined by Student's ‘T’ test or ANOVA followed by Bonferroni's post hoc test.

Results: T47Darom and T47DaromLR cell lines had significantly higher aromatase expression (mRNA and protein) and as a result exhibited increased conversion of testosterone to estradiol as compared to T47Dcon. Both these cell lines showed enhanced growth in the presence of Testosterone. In T47Darom cells increased PR-B and EGFR expression as compared to T47Dcon cells was observed. Proellex, Letrozole and other known AI (Anastrozole, Exemestane) inhibited testosterone induced cell proliferation and anchorage independent growth of T47Darom cells. The inhibition of cell proliferation was significantly greater when cells were treated with Proellex in combination to other AIs. Proellex inhibited mRNA and protein levels of PR-B, reduced PRB/p300 complex formation in the nuclei and significantly reduced EGFR expression in T47Darom cells. Our results in the present study indicate that antiproliferative effect of Proellex may be due to PR-B/EGFR modulation in ER+PR+, aromatase overexpressing cells.

Conclusion: Overall these results suggest that antiprogestin, Proellex could be developed as a possible treatment strategy for aromatase overexpressing ER+/PR+ breast cancer patients as well as for AI resistant breast cancer patients.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P2-17-05.

Actions of vitamin D are mediated by the TLR4 pathway in inflammation-induced colon cancer

Many chronic inflammatory diseases are associated with increased risk of developing cancer. In the colon, strong support for a link between chronic inflammation and cancer extends, in part, from population-based studies of persons with inflammatory bowel disease (IBD). Patients with IBD are at increased risk of developing colorectal cancer (CRC). The general consensus is that IBD results from the combined effects of genetics and environment factors known to affect the immune system. Vitamin D, an important regulator of the immune system, has been linked to IBD. Despite the strong potential reported for 1,25-dihydroxyvitamin D (1,25-OH)2D), its effects on calcium metabolism limits its application. Recently, less active vitamin D metabolites, cholecalciferol and 25-hydroxyvitamin D (25(OH)D), have gained considerable attention as promising agents against IBD-related colon cancer. Yet, their anti-proliferative properties and mechanism of action remain to be better defined. We present several signaling pathways commonly regulated by vitamin D compounds and highlight their regulation on TLR4. The efficacy of 25(OH)D and 1alpha-hydroxyviatmin D5 are evaluated using the azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced IBD-related colon carcinogenesis model. In summary, vitamin D supplementation may provide a cost-effective approach to reduce IBD related colon cancer.

Resveratrol inhibits rhabdomyosarcoma cell proliferation

Rhabdomysarcoma is the most common soft tissue tumour in children under the age of 15. Although the introduction of multimodal treatment programmes, including chemotherapy, radiation therapy and excision have increased the overall survival, the chemotherapeutic agents currently used for the treatment of rhabdomyosarcoma exhibit considerable toxicity. The aim of this study was to investigate the effects and possible mechanism(s) of action of resveratrol on human embryonal rhabdomyosarcoma (RD) cells. Resveratrol is a natural polyphenolic compound produced in a number of edible plants and has received considerable attention as a potential chemopreventive and/or chemotherapeutic agent against various types of cancers. In the present study, resveratrol was shown to inhibit cell proliferation of RD cells in a dose-dependent manner with an IC50 of 48.1 micromol/l and induce an arrest in the S/G2 phase of the cell cycle. As evident from immunocytochemical data, resveratrol treatment increased the size of the RD cells. Furthermore, resveratrol treatment resulted in a significant downregulation of cyclin B expression as demonstrated by western blot analyses. In conclusion, the present study shows that resveratrol exerts a strong inhibition of rhabdomyosarcoma cell proliferation in part by arresting cells in S/G2 phase of the cell cycle. These findings warrant further investigation to establish potential use of resveratrol as a relatively non-toxic chemotherapeutic agent for the treatment of rhabdomyosarcoma.

Cruciferous vegetables and cancer prevention

In recent years, cancer prevention by natural products has received considerable attention. The potential protective role of cruciferous vegetables and active components present in these vegetables, such as isothiocyanates and indole-3-carbinol, has been extensively studied in experimental in vitro and in vivo carcinogenesis models. Results have consistently shown that the chemopreventive agents derived from this class of vegetables of the Cruciferae family influence carcinogenesis during initiation and promotion phases of cancer development. Similarly, reports from epidemiological studies and clinical trials support this notion. However, there is no comprehensive summary of all these aspects of the association between cruciferous vegetables and cancer prevention. We have attempted to summarize experimental carcinogenesis studies as well as clinical trials and studies on the mechanism of action of selective chemopreventive agents isolated and identified within these natural products. Results clearly point toward a positive correlation between cancer prevention of many target organs and consumption of cruciferous vegetable or their active constituents. Yet we are still far from complete understanding of the effects of combinations of chemopreventive phytochemicals present in these cruciferous vegetables and their overall mechanism(s) of action in providing protective effects.

Deguelin inhibits the growth of colon cancer cells through the induction of apoptosis and cell cycle arrest

As previously demonstrated, deguelin [(7aS, BaS)-13, 13a-dihydro-9,10-dimethoxy-3,3-dimethyl-3H-bis[1]benzo-pyrano[3,4-b:6',5'-e]pyran-7(7aH)-one mediates anti-proliferative properties in a variety of cell types. In the present study, deguelin was found to suppress the growth of HT-29 colon cancer cells with an IC(50) of 4.32 x 10(-8) M. The cells were arrested in the G1-S-phase of the cycle. Investigations of G1/S regulatory proteins by Western blot analyses showed an upregulation of p27, and decreased expression levels of cyclin E and CDK4. Furthermore, by 24 h, exposure to deguelin resulted in an increase in the hypophosphorylated form of Rb. Since hypophosphorylated pRb binds to and inactivates E2F1, additional studies were performed and downregulation of E2F1 was observed after 24 h of treatment with deguelin. These results are consistent with the observation that deguelin arrested cells in the G1-S- phase. In addition, based on ethidium bromide/acridine orange staining, detection of digoxigenin-labelled genomic 3'-OH DNA ends, and DNA laddering, it was found that deguelin exerts its growth inhibitory effects via the induction of apoptosis. Based on these data, the potential of deguelin to serve as a cancer chemotherapeutic agent for colon cancer may be suggested.

Breast cancer risk factors in two distinct ethnic groups: Indian and Pakistani vs. American premenopausal women

Asian Indians from the Indian subcontinent have low rates of breast cancer, but studies on breast cancer risk factors in Indian and Pakistani women living in the United States are lacking. This study contrasted breast cancer risk factors [serum total 17 beta-estradiol (E2), sex hormone-binding globulin-bound E2, available E2, estrone (E1), and dehydroepiandrosterone sulfate, reproductive history, family history of cancer, body composition/size, dietary intake, physical activity, and excretion of isoflavones] between two distinct ethnic groups of premenopausal women residing in the United States. We also determined the contribution of these and other factors to the variability of each sex hormone. Distributions of values for serum total E2, available E2, and sex hormone-binding globulin-bound E2 (%) were greater (p < 0.005) in American (n = 47) than in Indian and Pakistani (n = 47) women. Multiple regression analysis indicated that 26% of the variability (p < or = 0.0001) in serum E2 was accounted for by the ratio of total cholesterol to high-density-lipoprotein cholesterol, length of time in the United States, and saturated fat intake, whereas less (17%) variability was accounted for by available E2 (representing free E2 + albumin-bound E2), contributed by the ratio of total cholesterol to high-density-lipoprotein cholesterol and saturated fat intake. Five variables accounted for 31% of the variability (p < or = 0.0001) in E1. The major finding of this study was that circulating sex hormone concentrations were determined more by environmental factors than by ethnicity, which was not a significant contributor to any of the serum hormones.

Cardiovascular disease risk factors in 2 distinct ethnic groups: Indian and Pakistani compared with American premenopausal women

BACKGROUND

Although people from the Indian subcontinent have high rates of cardiovascular disease (CVD), studies of such in Indian and Pakistani women living in the United States are lacking.

OBJECTIVE

This study accounted for variability in serum lipid (total cholesterol and triacylglycerol) and lipoprotein [LDL cholesterol, lipoprotein(a), and HDL cholesterol] concentrations in Indian and Pakistani compared with American premenopausal women in the United States. Body composition, regional fat distribution, dietary intake, and energy expenditure were compared between groups.

DESIGN

The 2 groups were 47 Indian and Pakistani and 47 American women. Health was assessed via medical history, physical activity, body composition (via anthropometry and dual-energy X-ray absorptiometry), dietary intake (via 7-d food records), and serum lipids.

RESULTS

Serum total cholesterol, triacylglycerol, LDL cholesterol, lipoprotein(a), the ratio of total to HDL cholesterol, and the ratio of LDL to HDL cholesterol were greater (P <0.03), whereas HDL-cholesterol values were lower (P = 0.011) in Indians and Pakistanis than in Americans. Multiple regression analysis indicated that approximately 18% of the variance in total cholesterol (P = 0.0010) and LDL cholesterol (P = 0.0009) was accounted for by ethnicity, energy expenditure, and the ratio of the sum of central to the sum of peripheral skinfold thicknesses. Ethnicity, sum of central skinfold thicknesses, ratio of polyunsaturated to saturated fat, and monounsaturated fat intake accounted for approximately 43% of the variance in triacylglycerol concentration (P < 0.0001). Monounsaturated fat, percentage body fat, and alcohol intake accounted for approximately 26% of variance in HDL cholesterol. Ethnicity contributed approximately 22% of the 25% overall variance in lipoprotein(a).

CONCLUSIONS

Results suggest that these Indian and Pakistani women are at higher CVD risk than their American counterparts, but that increasing their physical activity is likely to decrease overall and regional adiposity, thereby improving their serum lipid profiles.

Urbanization, the informal sector and migration: issues for research and cooperation

Only recently have development studies begun to examine the complex set of relationships between urbanization, the growth of the informal sector, and internal migration in Latin America. This paper suggests that the economic crisis of the 1980s has resulted in significant changes in these phenomena and that 1 of the most important changes has been the growth of return international migration between Latin American countries. Also of importance are the continued migration flows to North America. The paper argues that the interconnectedness of these phenomena requires more multinational research efforts.