Molecular signaling in cancer stem cells of tongue squamous cell carcinoma: Therapeutic implications and challenges

Head and neck squamous cell carcinoma is the seventh most common cancer worldwide with high mortality rates. Amongst oral cavity cancers, tongue carcinoma is a very common and aggressive oral cavity carcinoma. Despite the implementation of a multimodality treatment regime including surgical intervention, chemo-radiation as well as targeted therapy, tongue carcinoma shows a poor overall 5-year survival pattern, which is attributed to therapy resistance and recurrence of the disease. The presence of a rare population, i.e., cancer stem cells (CSCs) within the tumor, are involved in therapy resistance, recurrence, and distant metastasis that results in poor survival patterns. Therapeutic agents targeting CSCs have been in clinical trials, although they are unable to reach into therapy stage which is due to their failure in trials. A more detailed understanding of the CSCs is essential for identifying efficient targets. Molecular signaling pathways, which are differentially regulated in the CSCs, are one of the promising targets to manipulate the CSCs that would provide an improved outcome. In this review, we summarize the current understanding of molecular signaling associated with the maintenance and regulation of CSCs in tongue squamous cell carcinoma in order to emphasize the need of the hour to get a deeper understanding to unravel novel targets.

Economic burden of limited English proficiency: A prevalence-based cost of illness study of its direct, indirect, and intangible costs

Aims

The primary objective of the present study was to evaluate the economic burden of limited English proficiency (LEP) by estimating its direct, indirect, and intangible costs. A secondary objective was to assess the impact of variables on the economic burden.

Design and Setting

A cross-sectional single-arm descriptive study conducted in a learning disability clinic in a public medical college in Mumbai.

Subjects and Methods

The study cases (aged ≥8 years and ≤18 years) were recruited by non-probability sampling. A structured questionnaire was used to interview the parent to collect data related to direct and indirect costs. Intangible cost data were collected by documenting the willingness-to-pay value using the contingent valuation technique.

Statistical Analysis Used

A multivariate regression model was used to assess the impact of predictor variables on the costs.

Results

The direct, indirect, and intangible costs due to LEP were Indian Rupees (INR) 826,736, 3,828,220, and 1,906,300, respectively. Indirect costs comprised 82.2% of the total costs. Expenditure on tuition and remedial education comprised 39.86% and 14.08% of the indirect and direct costs, respectively. The average annual learning disability clinic costs were INR 2,169,146. The average annual total costs per student were INR 42,102. Higher socioeconomic status was predictive of increased "indirect costs", "total costs", and "intangible costs."

Conclusion

LEP is a cost-intensive condition (indirect > intangible > direct costs). Non-medical costs are the costliest component of direct costs. Parental loss of earnings is the costliest component of indirect costs.

Cancer Stem Cells, CD44, and Outcomes Following Chemoradiation in Locally Advanced Cervical Cancer: Results From a Prospective Study

PURPOSE

Although cancer stem cells (CSCs) have been reported across solid tumors, there is a dearth of data regarding CSC and its impact on outcomes of cervical cancer.

METHODS AND MATERIALS

From October 2013 to December 2015, patients with squamous cancer of the cervix (stage IB2-IVA) were included. Pretreatment and posttreatment biopsy was obtained and immunohistochemistry was performed for SOX-2, OCT-4, Nanog, CD44, and Podoplanin. All patients received concurrent radiation and brachytherapy to an equivalent dose of 80 to 84 Gy to point A with concurrent weekly cisplatin. Correlation of CSC expression was performed with known prognostic factors. The effect of stem cell expression on disease outcomes was tested within multivariate analysis.

RESULTS

One hundred fifty patients were included. The median dose to point A was 83 Gy (46-89 Gy) and a median of 4 cycles (range, 0-6 cycles) of chemotherapy was administered. At baseline, moderate to strong immunohistochemical expression of SOX-2, OCT-4, Nanog, CD44, and Podoplanin was observed in 12.8%, 4.8%, 24.4%, 15.5%, and 1.3% of patients, respectively. At median follow-up of 30 months (range, 3-51 months), locoregional and distant relapse was observed in 12.2% and 23.1% of patients, of whom 4.7% had both local and distant relapse. The 3-year disease-free survival rate was 87%. On multivariate analysis, moderate to high CSC expression and CD44 low status (hazard ratio [HR] = 8.8; 95% confidence interval [CI], 1.0-77.2; P < .04) independently predicted for locoregional relapse-free survival. International Federation of Gynecology and Obstetrics stage (HR = 2.6; 95% CI, 1.3-5.4; P = .004) and presence of residual tumor after external radiation (HR = 3.5; 95% CI, 1.8-6.5; P = .0001) predicted for a detriment in disease-free survival.

CONCLUSIONS

The presence of stem cell proteins and loss of CD44 independently predicts for reduced locoregional control in locally advanced cervical cancer. Further investigation into the interaction of stem cell and CD44 biology is warranted.

435 REDUCTION OF CELL CYCLE LENGTH AND INCREASE IN S-PHASE BY GROWTH FACTORS IN PIG FETAL FIBROBLASTS

Gene targeting in primary somatic cells is inefficient compared with embryonic stem cells. This is because of a slow rate of cell proliferation, fewer cells in S-phase at a given time point under normal culture conditions, and low rate of homologous recombination. Homologous recombination occurs mainly in late S-phase and increase in gene targeting efficiency has been reported in S-phase synchronized cells in bovine and rhesus macaque fetal fibroblasts. In this study we tested several growth factors: platelet-derived growth factor (PDGF), tumor necrosis factor a (TNFα), epidermal growth factor (EGF), fibroblast growth factor (FGF), transforming growth factor β1 (TGFβ1), insulin-like growth factor 1 (ILGF-1) and insulin-like growth factor II (ILGF-II) individually and in various combinations to see the effect on cell proliferation rate. Each experimental set consisted of 3 replicates. TGFβ1-, ILGF1-, ILGFII-, and FGF-treated cells grew very slowly compared with untreated cells. However, a combination of 3 growth factors: PDGF (15 ng mL-1), EGF (50 ng mL-1) and TNFa (100 pg mL-1), herein referred to as the cocktail, accelerated cell proliferation rate and reduced cell cycle length on average from 24.5 ± 0.2 to 20.4 ± 0.5 h with no significant change in number of cells in S-phase. Further, cells grown in the presence of the cocktail showed changes in morphology. The cells became spindle-shaped and occupied less surface area per cell compared with untreated cells. Importantly, cocktail-treated cells maintained a normal karyotype without any chromosomal abnormality. Thymidine has been used successfully to block various cell types in S-phase but it failed to synchronize these cells in S-phase in the concentration range of 2 to 10 mM for 24 to 48 h. However, serum starvation (0.2% fetal bovine serum) for 48 h blocked the cell proliferation rate effectively and synchronized cells in G0 phase (80-82% cells). After releasing from the block, cells were grown in the absence or presence of cocktail and cell cycle analysis was done at different time points by flow cytometry. Each time point was repeated 3 times. We observed the maximum number of cells in S-phase at 22 to 23 h (61.33% ± 7.77 in cocktail-treated cells v. 41.7% ± 3.28 in untreated cells). In summary, the cocktail-treated cells showed changes in cell morphology, higher proliferation rate, reduction in cell cycle length by 16.7%, and maximum percentage of cells in S-phase following serum starvation but maintained normal karyotypes. This high proliferation rate, reduction in cell cycle length, and maximum number of cells in S-phase should be very helpful in increasing the efficiency of gene-targeting in pig fetal fibroblasts.

66 ISOLATION, CHARACTERIZATION, AND NUCLEAR REPROGRAMMING OF STEM CELLS DERIVED FROM ADULT PORCINE LIVER AND FAT

Genetic manipulation of the porcine genome to produce genetically modified pigs for various biomedical and agriculture applications has been hampered by the lack of an ideal cell type that can grow in culture for a long period of time and is amenable to various genetic manipulations with high efficiency. The cell type currently used for various genetic manipulations is fetal fibroblast. These cells have very limited life span in culture and the efficiency of gene targeting is very low. There is no report of isolation of functional embryonic stem cells (ESC) from pig that would have been used to produce transgenic pigs with high efficiency as has been possible in mice. Recently, porcine induced pluripotent stem cells (iPSC) have been reported by 3 groups. However, they have yet to be tested for genetic manipulations and production of transgenic pigs. In this study, we developed a simple but novel strategy to recover stem cells from adult porcine liver and adipose tissues. Small colonies with few cells became visible as early as 2 to 3 days under reduced oxygen conditions on collagen-coated plates, and a full-grown colony with a fibroblast-like morphology took 10 to 14 days to form. Ten single colonies per tissue were isolated, subcultured, and monitored for growth and gene expression. Both of these cell types maintained steady growth through 70 population doublings (at the time of writing) and are still growing without any change in their morphology. Reverse transcription PCR was used to monitor gene expression. Both cell types show strong expression of c-Myc and KLF4. Moreover, low expression of Oct-4 and Lin28, 2 important genes related to pluripotency, was also detected in cells derived from adipose tissues, indicating that these cells could be easily reprogrammed to pluripotent state. These cells maintained a normal karyotype after long-term culture. Cell lines with stable genetic modifications and extended expression of transgene were obtained when these cells were transfected with a plasmid containing the neomycin resistance gene and selected under G418. Further, these 2 cell types, liver stem cells (LSC) and fat stem cells (FSC), and fetal fibroblasts (FF) as a control were used as nuclear donors to produce somatic cell nuclear transfer (SCNT) embryos. The average fusion rates were 87, 81, and 89% for LSC, FSC, and FF, respectively. Of 2 recipients receiving nuclear transfer embryos produced with each cell type, one established pregnancy at Day 30 (50%). Efficiencies were 5% (11 fetuses/223 embryos transferred), 1.8% (4 fetuses/228 embryos transferred),and 5% (11 fetuses/219 embryos transferred) for LSC, FSC, and FF, respectively. Thus, these adult liver and fat stem cells are attractive cell types for cloning valuable adult animals with high efficiency and for SCNT transgenesis.

Polydeoxycholate in human and hamster feces: a major product of cholate metabolism

Fecal bile acid excretion is one of the two major routes by which cholesterol is eliminated from the body, fecal cholesterol being the other. During their enterohepatic circulation, bile acids are secreted into the duodenum, pass down the jejunum and into the ileum where more than 95% is reabsorbed by the gut. Bile acids that escape reabsorption in the small intestine are metabolized by microorganisms in the large intestine. The major routes of metabolism are reported to be deconjugation, dehydroxylation, especially at the 7 alpha-hydroxy position, and dehydrogenation of the hydroxyl moieties. There are also some reports that saponifiable metabolites containing mostly deoxycholic acid form a major component of the bile acids found in human feces. We have identified a novel metabolite of cholic acid, 3 alpha-hydroxy polydeoxycholate, in both human and hamster feces that is the major constituent of these saponifiable metabolites. Furthermore, we have shown in hamsters that the animals that excreted more bile acid were excreting the additional bile acid as polydeoxycholate. As expected, there was a negative correlation between bile acid excretion in the feces and plasma cholesterol concentrations in these animals. We speculate that polydeoxycholate is formed in the lower gut of both humans and hamsters and that, by its formation, bile acid will be sequestered in an insoluble form, thus inhibiting its reabsorption by the gut. This process may help to reduce plasma cholesterol concentrations and coronary heart disease in humans.