Preparation and stability of sixteen murine tissues and organs for flow cytometric cell cycle analysis

Chronomodulated oxaliplatin plus Capecitabine (XELOX) as a first line chemotherapy in metastatic colorectal cancer: A Phase II Brunch regimen study

PURPOSE

The aim of this study was to evaluate safety and toxicity of chronomodulated capecitabine administered in the morning and at noon according to a specific time schedule (Brunch Regimen: Breakfast and Lunch) as a part of first-line XELOX chemotherapy in patients with metastatic colorectal cancer.

METHODS

A total of 30 treatment-naïve colorectal cancer patients with metastatic disease were included. Oxaliplatin 130 mg/m(2) on day 1 plus chronomodulated oral capecitabine 2000 mg/m(2) per day were administered (50 % dose at 8:00 a.m. and 50 % dose at 12:00 noon on days 1-14, every 21 days). All adverse events, treatment responses and survival were evaluated. In addition, pharmacokinetic profile of capecitabine was examined in a subset of 5 patients.

RESULTS

Median age was 57.1 years (range 32-77 years). Median follow-up was 19 months (range 3-36 months). Three patients (10 %) had complete response, 13 patients (43.3 %) had partial response and 4 patients (13.3 %) had stabile disease. Ten patients had progressive disease at their first evaluation (33.3 %). The median progression-free survival (PFS) was 10 months (range 2-36 months). There were no grade 4 toxicities. One patient (3.3 %) had grade 3 neutropenia. Hand-foot syndrome developed in three patients (10 %): 6.6 %, grade 1 and 3.3 %, grade 2.

CONCLUSIONS

Chronomodulated XELOX seems to represent a promising therapeutic option in the first-line treatment of metastatic colorectal carcinoma due to good tumor control and favorable toxicity profile. Phase III randomized trials are required to assess the actual clinical efficacy and side effect profile of this regimen.

High-resolution cell cycle and DNA ploidy analysis in tissue samples

This unit describes an easy, rapid, and universal procedure to process fresh and nitrogen-frozen tissue specimens for high-resolution cell cycle and DNA ploidy analysis. Unlike other protocols, this procedure does not require treating tissues with enzymes, detergents, or other plasma membrane-lysing chemicals, but it achieves tissue dispersion by a simple two-step mechanical process that can be performed in ∼5 min. Resulting single-cell suspensions are fixed with ethanol, stained with propidium iodide, and subjected to flow cytometric DNA content analysis. The method can be applied without any alterations to all tissue types (except bones) derived from several species and results in highly reproducible cell cycle profiles of excellent resolution. The described protocol can be used to reliably and accurately detect subtle cell cycle and ploidy alterations in tissue specimens, including cell cycle arrest, aneuploidy, and apoptosis/necrosis-associated DNA fragmentation.

A rapid and optimization-free procedure allows the in vivo detection of subtle cell cycle and ploidy alterations in tissues by flow cytometry

Cell cycle alterations are fundamental to many physiological processes but their detection has proven difficult when cells are in the context of a tissue structure. Here we describe an easy, rapid and optimization-free procedure for obtaining high resolution cell cycle profiles from nearly all tissue types derived from mouse, human and sheep. Using a standardized and non-enzymatic procedure that is universally suitable for soft, solid and epithelial tissues alike, we reproducibly obtain cell cycle profiles of highest quality with half peak coefficients of variation below 2.0. We are able to reduce preparation-derived debris to almost zero and efficiently exclude doublets, but retain multinucleated cells and apoptotic subG1-fragments. Applying this technique, we determine DNA-indices as small as 1.09 in tumor samples containing large necrotic areas and follow ploidy changes within different sections of individual tumors. Moreover, we examine tissue-specific cell cycle arrest and apoptosis as an in vivo stress response caused by radiation of mice. This method significantly improves the quality of DNA content analysis in tissues and extends the spectrum of applications. It allows assessing changes in ploidy, cell cycle distribution and apoptosis/necrosis in vivo and should be instrumental in all research that involves experimental animal models and/or patient biopsies.

A simple and fast method for cell recovery and DNA content analysis from various mouse tissues by flow cytometry

Cell division in tissues can be investigated in various ways. We present here a method for improving cell recovery and cell cycle analysis for a wide range of mouse tissues. This strategy combines a cell isolation procedure for various mouse tissues based on intracardiac perfusion and subsequent treatment followed by flow cytometry. This easy and reproducible method allows a rapid analysis of nuclear DNA content, providing an estimate of the cell number at different phases of the cell cycle. This combined procedure could also be used for the isolation of specific cell subpopulations from different mouse tissues by fluorescence activated cell sorting.

Increased nuclear ploidy, not cell proliferation, is sustained in the peroxisome proliferator-treated rat liver

Peroxisome proliferators are believed to induce liver tumors in rodents due to sustained increase in cell proliferation and oxidative stress resulting from the induction of peroxisomal enzymes. The objective of this study was to conduct a sequential analysis of the early changes in cell-cycle kinetics and the dynamics of rat liver DNA synthesis after treatment with a peroxisome proliferator. Immunofluorescent detection of proliferating cell nuclear antigen (PCNA) and bromodeoxyuridine (BrdU) incorporation into DNA during S phase we used to assess rat hepatocyte proliferation in vivo during dietary administration of Wy-14,643, a known peroxisome proliferator and hepatocarcinogen in rodents. Rats were placed on diet containing 0.1% WY-14,643 and implanted subcutaneously with 5-bromo-2'deoxyuridine containing osmotic pumps 4 days prior to being sacrificed on days 4, 11, and 25 of treatment. Isolated liver nuclei labeled with fluorscein isothiocyanate (FITC)-anti-BrdU/PI and FITC-anti-PCNA/PI were analyzed for S-phase kinetics using flow cytometry. Morphometric analysis was performed to evaluate nuclear and cell size and enumeration of BrdU labeled cells, binucleated hepatocytes, and mitotic index. The BrdU labeling index increased 2-fold in livers of Wy-14,643-treated rats at day 4, but distribution of cells in G1, S phase, and G2-M did not differ significantly from controls. PCNA-positive cells decreased from 36% on day 4 to 17% on day 25, whereas the percentage of PCNA-positive cells in controls increased 2-fold from day 4 to day 11 and remained unchanged up to day 25. The differences in the number of PCNA-positive nuclei between control and Wy-14,643-treated groups were statistically significant only on day 4. Binucleated hepatocytes, determined by morphometric analysis, increased slightly on day 25 in treated rats parallel to an increase in the percentage of cells in G2-M phase. Significant shifts were noted in nuclear diameter and nuclear area after 11 and 25 days of treatment with Wy-14,643. Hepatic cell populations with nuclei > 9 microns diameter and nuclear area > 64 microns2 increased in Wy-14,643-fed rats during the treatment period compared with the control, indicating hepatic karyomegaly and hyperploidy, whereas percentage of distribution of nuclei based on diameter and area remained consistently unchanged in control animals from 4 through 25 days of sham treatment. The flow cytometric and morphometric analysis indicated an initial wave of DNA synthesis in response to Wy-14,643. The hepatomegaly was sustained over the treatment period accompanied by increase in ploidy with a significant shift toward hyperploidic hepatocytes. The increase in DNA content was almost entirely accounted for by the overall polypoidy increase rather than by an absolute increase in cells.

Methodologies for the preservation of proliferation associated antigens PCNA, p120, and p105 in tumor cell lines for use in flow cytometry

The retention of antigen expression of PCNA, p120, and p105 in two tumor cell lines (MOLT-4 and MDA-MD-175-VII) under various conditions of fixation was investigated using flow cytometric analysis. Four currently utilized procedures for fixation/permeabilization of intracellular antigens were compared for their ability to stain the nuclear antigens. A procedure using a brief incubation in a solution of lysolecithin in paraformaldehyde followed by fixation in ice-cold methanol prior to antibody staining was selected to evaluate reagent protocols aimed at preserving antigen expression. Holding samples overnight at 4 degrees C in 2.5% fetal bovine serum after the lysolecithin/paraformaldehyde and methanol fixation steps prior to staining with monoclonal antibodies resulted in no decline in the percentage of cells positively stained for all three markers with little decrease in intensity of fluorescence and no increase in DNA coefficient of variation (c.v.). Fixed/permeabilized MOLT-4 cells held longer than 24 h before staining were lower in PCNA fluorescence than freshly stained cells; holding samples of either cell line longer than 48 h resulted in decreased PCNA and p120 staining. Prefixing and holding cells in 50% methanol or 50% ethanol overnight before processing and staining severely depressed PCNA and p120 fluorescence. Prefixing either cell line in a range of concentrations (0.25-1.0%) of paraformaldehyde also resulted in reduced intensity of PCNA and p120 fluorescence along with increased DNA c.v. P105 staining appeared to be relatively unaffected by all prefixation/storage conditions tested, except for a decline of fluorescence when MDA cells were prefixed in 50% ethanol. Cells cryopreserved in liquid nitrogen for 1 week before processing showed < 5% loss of PCNA and p120 fluorescence compared to freshly processed cells, but p105 fluorescence dropped 29% in cryopreserved MDA cells. These results underscore the fact that specific protocols for the fixation and storage of biological samples prior to staining and analysis must be determined for the specific nuclear antigen marker under investigation.

Comparative evaluation of fresh, fixed, and cryopreserved solid tumor cells for reliable flow cytometry of DNA and tumor associated antigen

Five different protocols for the short-term preservation of cells used for multiparameter flow cytometric assay of tumour associated antigens (TAA) and DNA were assessed in cell suspensions prepared by mechanical disaggregation of 15 gynecological tumors. The protocols at 4 degrees C were 1) storage in buffer, 2) storage in 50% methanol, and 3) storage in buffer after formalin fixation. Tissues were also cryopreserved as cell suspensions and tissue blocks. When the TAA expression and DNA histograms of the preserved cells were compared with those in fresh cell suspensions, cryopreservation was found to be the best method: TAA expression was well preserved and there was a good correlation between TAA expression and the quality of the DNA histograms, respectively, in fresh and cryopreserved cells (RS: 0.82-0.91, P less than 0.001 for all TAAs). The cell suspensions preserved at 4 degrees C all showed a significant increase in background fluorescence (P less than 0.05) and a reduction in the TAA specific fluorescence (P less than 0.011). Methanol fixation was better than buffered formalin for the proteins studied, though both gave significantly worse results than cryopreservation. The quality of these cell suspensions and the correlation with TAA measurements in fresh cell suspensions deteriorated progressively with time, particularly if they were stored more than a week.

Flow cytometric DNA analysis of corneal epithelium

We have modified an existing technique in order to perform DNA analysis by flow cytometry (FCM) of corneal epithelium from the mouse, rat, chicken, rabbit, and human. This protocol permitted an investigation of human corneal scrapings from several categories: normal, aphakic bullous keratopathy (ABK), keratoconus (KC), Fuch's dystrophy, edema, epithelial dysplasia, and lipid degeneration. No abnormal characteristic cell-kinetic profile was detected when averaged DNA histograms were compared statistically between the normal and either ABK, KC, edema, or Fuch's dystrophy groups. Abnormal DNA histograms were recorded for cell samples that were taken 1) from three individuals who had epithelial dysplasia and 2) from one individual diagnosed with lipid degeneration. The former condition was characterized by histograms that had a subpopulation of cells with an aneuploid amount of DNA or had higher than normal percentages of cells in the S and G2 + M phases of the cell cycle. Corneal cells from the patient who had lipid degeneration had an abnormally high percentage of cells in the G2 + M phases of the cell cycle. The availability of accurate DNA flow cytometric analysis of corneal epithelium allows further studies on this issue from both experimental and clinical situations.

In vitro antiproliferative activity of 2'-(2-hydroxyphenyl)-2'-thiazoline-4'-carboxylic acid and its methyl ester on L1210 and P388 murine neoplasms

The activity of three iron chelators, methyl [2'-(2-hydroxyphenyl)-2'-thiazoline-4'-carboxylate] (MTL); 2'-(2-hydroxyphenyl)-2'-thiazoline-4'-carboxylic acid (TFAL); and 2-hydroxyphenyl-imido-ethyl-ether (Imidate), regarding antiproliferative, cytocidal, and cell-cycle effects are reported and compared with hydroxyurea (HU). In vitro, against L1210 and P388 murine neoplasms, MTL and TFAL displayed substantially greater antiproliferative activity than HU, although Imidate displayed no appreciable activity. MTL also induced a statistically more complete G1/S cell-boundary block than did HU at equimolar concentrations (100 microM). The IC50 values produced by MTL and TFAL were low enough (less than or equal to 20 microM) to warrant further testing of these chelators as potential antineoplastic agents.

Biological time and the effects of hydroxyurea on DNA synthetic activity of bone marrow and tumor cells in mice bearing the Ehrlich ascites carcinoma

The objective of this experiment was to attempt to induce, with hydroxyurea (HU), significant quantitative differences in the level of DNA-synthetic activity (DNA-SA) between a neoplastic cell population (the Ehrlich ascites carcinoma or EAC) and bone marrow in the same animal. Mice bearing a 5-day-old EAC were standardized to and kept on an LD 12:12 cycle (light 0600-1800 hr). They were treated with 500 mg/kg HU at 0500 hr (23 hr after lights on, or HALO) or at 1700 hr (11 HALO). DNA-SA was determined by liquid scintillation counting of 3H-thymidine incorporation into chemically isolated DNA. DNA-SA in bone marrow and EAC cells was monitored over the next 60 hr with subgroups of ten mice each killed every 3 hr beginning 3 hr after treatment with HU. The circadian system of the host influenced the response of the bone marrow to HU; i.e., the response to HU administered at 0500 hr was different both qualitatively and quantitatively from that for HU given at 1700 hr. Comparisons of DNA-SA in bone marrow and EAC from the same animal revealed time points after treatment with HU when DNA-SA in the EAC was high, but DNA-SA in bone marrow was low. These differences in the level of DNA-SA between a tumor cell population and bone marrow should be of therapeutic value; i.e., executor doses of anti-DNA-SA drugs such as cytosine arabinoside could be given at that point in time after treatment with HU when DNA-SA in the tumor was high, but DNA-SA in the bone marrow was low.

Short-term cryopreservation of human breast carcinoma cells for flow cytometry

A procedure is described for short-term cryopreservation of primary human tumor cells and tissue slices for later analysis by flow cytometry. Cells were mechanically dispersed into a freezing medium, which was then frozen at either -20 degrees C or -70 degrees C for delayed cell cycle analysis. The results show that a correlation coefficient of greater than 0.95 exists between cell cycle kinetic analyses performed immediately after surgical excision of the tumor and on cells frozen from 1 to 30 days at -70 degrees C in this freezing solution. Somewhat lower levels of correlation exist for cells frozen at -20 degrees C in this freezing medium. This procedure has also been successfully used to preserve freshly isolated breast carcinoma cells shipped from distant laboratories for analysis in the flow cytometer, thus expanding the data base on certain types of breast carcinoma.

Circadian influence on the metaphase arrest technique in mouse cornea (light microscopy study) and rectum (flow cytometry study)

Vincristine (VC) was used to arrest metaphases in the epithelium of the cornea and rectum. The cornea was studied by light microscopy (mitotic index). The rectum was analyzed by flow cytometry (%G2 + M). The results of a dose range finding study showed that 3.0 mg/kg body weight VC did not increase the number of metaphases in the cornea or the %G2 + M for the rectum over that recorded for a dose of 1.0 mg/kg VC. Therefore 1.0 mg/kg VC was selected as the dose to use. Mice were kept on a 12:12 light-dark cycle with light from 0600 to 1800. Mice were treated with 1.0 mg/kg VC at either 0200 or 1400. 0200 is a time when the native mitotic index is increasing toward a peak level, which is attained at 0800-1000 under these conditions. 1400 is a time when the mitotic index is decreasing to trough level, which is attained at 2000 to 2200. In one experiment, subgroups of mice were killed at +3 (0500 or 1700) and +6 (0800 or 2000) hours after VC. In a replicate experiment subgroups were killed at +2 (0400 or 1600), +4 (0600 or 1800), and +6 (0800 or 2000) hours after VC. The data from the cornea (mitotic indices) and the rectum (%G2 + M) were graphed against time. For both organs the slope of the metaphase accumulation line was different when VC at 0200 data were compared to VC at 1400 data. The conclusion reached was that by changing the biological time of the experiment one can significantly change the slope of the line obtained with the stathmokinetic technique.