PDX models of human lung squamous cell carcinoma: consideration of factors in preclinical and co-clinical applications

Background

Treatment of human lung squamous cell carcinoma (LUSC) using current targeted therapies is limited because of their diverse somatic mutations without any specific dominant driver mutations. These mutational diversities preventing the use of common targeted therapies or the combination of available therapeutic modalities would require a preclinical animal model of this tumor to acquire improved clinical responses. Patient-derived xenograft (PDX) models have been recognized as a potentially useful preclinical model for personalized precision medicine. However, whether the use of LUSC PDX models would be appropriate enough for clinical application is still controversial.

Methods

In the process of developing PDX models from Korean patients with LUSC, the authors investigated the factors influencing the successful initial engraftment of tumors in NOD scid gamma mice and the retainability of the pathological and genomic characteristics of the parental patient tumors in PDX tumors.

Conclusions

The authors have developed 62 LUSC PDX models that retained the pathological and genomic features of parental patient tumors, which could be used in preclinical and co-clinical studies.

Trial registration Tumor samples were obtained from 139 patients with LUSC between November 2014 and January 2019. All the patients provided signed informed consents. This study was approved by the institutional review board (IRB) of Samsung Medical Center (2018-03-110)

cDNA cloning of two isoforms of ornithine carbamoyltransferase from Canavalia lineata leaves and the effect of site-directed mutagenesis of the carbamoyl phosphate binding site

The immunoscreening method was used to isolate cDNAs of 1323 bp (ClOCT1) and 1433 bp (ClOCT2) encoding two ornithine carbamoyltransferases (OCT, EC 2.1.3.3) from the cDNA expression library of Canavalia lineata leaves constructed in a lambdaZAP Express vector. ClOCT1 and ClOCT2 encode 359 and 369 amino acids, respectively. The N-terminals of deduced amino acid sequences of the two cDNAs showed typical features of the transit peptide of chloroplast targeting proteins. The ornithine-binding domain (FMHCLP) and catalytic domain (HPXQ) of ClOCT1 and ClOCT2 and the carbamoyl phosphate (CP)-binding site of ClOCT1 (SMRTR) are identical to OCTs of other plant species, pea and Arabidopsis thaliana. However, the CP-binding site sequence of ClOCT2, SLRTH, has not yet been reported. Both ClOCT1 and ClOCT2 cDNAs were expressed in Escherichia coli BL21 (DE3) by using expression vector pET30a. Recombinant ClOCT1 protein showed 14 times higher ornithine-dependent OCT activity than canaline-dependent OCT activity. In contrast, recombinant ClOCT2 protein showed 13 times higher canaline-dependent OCT activity than ornithine-dependent OCT activity. The two amino acids of the CP-binding site of ClOCT2 (SLRTH) were combinatorially changed to those of the CP-binding site of ClOCT1 (SMRTR) by site-directed mutagenesis. When Leu-118 of ClOCT2 was changed to Met, ornithine-dependent activity was increased significantly. It is assumed that the substrate specificity of ClOCT1 or ClOCT2 proteins partially depends on the amino acid sequence of the CP-binding site.

Attitudes toward genetic testing in patients with colorectal cancer

PURPOSE

The purpose of this study was to examine risk perceptions and interest in genetic testing among African American and White patients with colorectal cancer.

DESCRIPTION OF STUDY

In this cross-sectional study, 98 patients with colorectal cancer participated in a brief structured telephone interview. Information was collected on knowledge and risk perceptions regarding colorectal cancer genetics, health behaviors, knowledge about the availability of genetic testing, and interest in genetic testing for colorectal cancer susceptibility.

RESULTS

Sixty-one percent of the participants were worried about their relatives' risk of colorectal cancer, and 64% were concerned about being a colorectal cancer susceptibility gene carrier. Although 81% of the participants reported that they had never heard about a genetic test for colorectal cancer susceptibility, 72% stated that they would want to take the test if it were available. Predictors of intention to have a genetic test were younger age, less advanced stage of disease, and more frequent thoughts about colorectal cancer being hereditary.

CLINICAL IMPLICATIONS

These results suggest that the demand for genetic testing may be great, despite a general lack of knowledge about colorectal cancer genetics and the potential risks and limitations of testing. Education and counseling about cancer genetics and genetic testing may clarify misconceptions about hereditary colorectal cancer and help patients with colorectal cancer and their family members make informed decisions about whether to undergo testing.

Interest in genetic testing among first-degree relatives of colorectal cancer patients

PURPOSE

The present study examined colorectal cancer screening behaviors, risk perceptions, and willingness to receive genetic testing to determine colorectal cancer susceptibility.

METHODS

We recruited 95 first-degree relatives of colorectal cancer patients, then conducted a brief telephone interview using a structured questionnaire that elicited information on sociodemographics, cancer screening behaviors, risk perceptions, and interest in genetic testing.

RESULTS

Among these high-risk individuals who were aged 40 years or older, only 31% reported fecal occult blood testing within the past year and 59% reported undergoing sigmoidoscopy or colonoscopy within the past 5 years. The majority of participants believed their relative risk of colorectal cancer was increased (68%). Eighty-four percent of the participants indicated that they would have a genetic test if one were available. Participants who believed that <50% of colorectal cancers were caused by heredity were more likely to be interested in genetic testing than were participants who believed that 50% or more of colorectal cancers were caused by heredity. Referral source, sociodemographic factors, clinical factors, and perceived personal risk were not significantly associated with interest in genetic testing.

CONCLUSION

Our results suggest that the demand for colorectal cancer susceptibility testing may be high among individuals with a family history of colorectal cancer. We also observed that a substantial number of first-degree relatives were not adhering to colorectal cancer screening guidelines. Accurate information on the genetic aspects of colorectal cancer and the benefits and limitations of genetic testing may help relatives of colorectal cancer patients make informed decisions about whether to undergo enhanced screening and genetic testing.

Molecular cloning and characterization of a plastid chaperonin 60 alpha subunit from Canavalia lineata

A 2040 bp cDNA encoding plastid chaperonin 60alpha protein was isolated from a cDNA expression library prepared from Canavalia lineata leaves. The sequence analysis of the clone showed a significant homology to those of other plant plastid chaperonin 60alpha. The genomic DNA blot analysis indicated that Canavalia lineata chaperonin 60alpha is encoded by a single gene in the genome. The short-term kinetics of light on the gene expression revealed that the remarkable accumulation of the gene occurred after 24 h. The mRNA was also detectable in dark-grown seedling leaves.

Inhibition of the growth of glioblastomas by CGP 41251, an inhibitor of protein kinase C, and by a phorbol ester tumor promoter

Protein kinase C (PKC) plays a central role in signal transduction pathways that mediate the action of certain growth factors, tumor promoters, and cellular oncogenes. To explore whether PKC might be an appropriate target for the chemotherapy of human brain tumors, cell lines were established from five glioblastomas, one mixed gliosarcoma and glioblastoma, two astrocytomas, and one choroid plexus carcinoma. The staurosporine derivative CGP 41251, an inhibitor of PKC, inhibited cell proliferation in all nine cell lines with an IC50 in the range of 0.4 micrometer. Drug withdrawal and clonogenicity assays showed that CGP 41251 induced an irreversible growth arrest. Three cell lines were examined in detail: two human glioblastoma cell lines, GB-1 and GB-2, and one gliosarcoma cell line, GS-1. All of these three cell lines were highly aneuploid and displayed morphologies and immunohistochemical markers characteristic of the glial lineage. The compound 12-O-tetradecanoylphorbol-13-acetate (TPA), a tumor promoter and activator of PKC, also inhibited the growth of these cell lines. CGP 41251 in combination with TPA caused further growth inhibition. Cultures treated with CGP 41251 displayed an increase in the fraction of cells in G2-M, a decrease of cells in S phase, and no consistent effect on G0-G1. Immunohistochemical analyses demonstrated that growth inhibition by CGP 41251 was associated with the formation of giant nuclei with extensive fragmentation and apoptotic bodies. These effects of CGP 41251 were abrogated by withdrawal of serum from the medium or by exposure of these cells to aphidicolin, actinomycin D, cycloheximide, or TPA. In contrast to the effects seen with the glioblastoma cell lines, nontransformed astrocyte lines remained viable in the presence of 0.4 and 0.8 micrometer CGP 41251 and displayed only a slight increase in the fraction of giant nuclei with fragmentation. The antitumor activity of CGP 41251 was demonstrated in vivo against xenografts of the glioblastoma cell lines U87 MG and U373 MG. These findings suggest that CGP 41251 might be a useful agent for the treatment of glioblastomas.