Ras oncogene expression and DNA content in plasma cell dyscrasias: a flow cytofluorimetric study

Histochemistry in Advanced Cytometry: From Fluorochromes to Mass Probes

For over half a century, fluorescence has been the milestone of most of the quantitative approaches in various fields from chemistry and biochemistry to microscopy. This latter also evolved into cytometry, thanks to the development of fluorescence techniques. The dyes of classical cytochemistry were replaced by fluorochromes, and the pioneer microphotometry was replaced by microfluorometry. The latter has great advantages in terms of simplicity, sensitivity, and accuracy. The extensive research and availability of new fluorochromes as well as the technological evolution contributed to the success of microfluorometry. The development of flow cytometry in the 1960s gave a giant boost to cell analysis and in particular to the clinical diagnostics. The synergy between flow cytometry and the subsequent development of monoclonal antibodies allowed the setup of multiparametric analytical panels that are today popular and irreplaceable in many clinical and research laboratories. Multiparametric analysis has required the application of an increasing number of fluorochromes, but their simultaneous use creates problems of mutual contamination, hence the need to develop new fluorescent probes. Semiconductor and nanotechnology research enabled the development of new probes called nanocrystals or quantum dots, which offered great advantages to the multiparametric analysis: in fact, thanks to their spectrofluorometric peculiarities, dozens of quantum dots may be simultaneously used without appreciable crosstalk between them. New analytical horizons in cytometry seem to be associated with a new concept of analysis that replaces fluorescence toward new markers with (non-radiative) isotopes of heavy metals. Thus, the mass flow cytometry was born, which seems to guarantee the simultaneous compensation-free analysis of up to 100 markers on a single sample aliquot.

Proliferation Pattern of Pediatric Tumor-Derived Mesenchymal Stromal Cells and Role in Cancer Dormancy: A Perspective of Study for Surgical Strategy

The explanation for cancer recurrence still remains to be fully elucidated. Moreover, tumor dormancy, which is a process whereby cells enter reversible G₀ cell cycle arrest, appears to be a critical step in this phenomenon. We evaluated the cell cycle proliferation pattern in pediatric tumor-derived mesenchymal stromal cells (MSCs), in order to provide a better understanding of the complex mechanisms underlying cancer dormancy. Specimens were obtained from 14 pediatric patients diagnosed with solid tumors and submitted to surgery. Morphology, phenotype, differentiation, immunological capacity, and proliferative growth of tumor MSCs were studied. Flow cytometric analysis was performed to evaluate the cell percentage of each cell cycle phase. Healthy donor bone marrow-derived mesenchymal stromal cells (BM-MSCs) were employed as controls. It was noted that the DNA profile of proliferating BM-MSC was different from that of tumor MSCs. All BM-MSCs expressed the typical DNA profile of proliferating cells, while in all tumor MSC samples, ≥70% of the cells were detected in the G0/G1 phase. In particular, seven tumor MSC samples displayed intermediate cell cycle behavior, and the other seven tumor MSC samples exhibited a slow cell cycle. The increased number of tumor MSCs in the G0-G1 phase compared with BM-MSCs supports a role for quiescent MSCs in tumor dormancy regulation. Understanding the mechanisms that promote dormant cell cycle arrest is essential in identifying predictive markers of recurrence and to promote a dedicated surgical planning.

Fluorochromes for DNA Staining and Quantitation

In these last few decades the great explosion of the molecular approaches has casted a little shadow on the DNA quantitative analysis. Nevertheless DNA cytochemistry represented a long piece of history in cell biology since the advent of the Feulgen reaction. This discovery was really the milestone of the emerging quantitative cytochemistry, and scientists from all over the world produced a very large literature on this subject. This first era of quantitation (histochemistry followed by cytochemistry) started by means of absorption measurements (histophotometry and cytophotometry). The successive introduction of fluorescence microscopy gave a great boost to quantitation, making easier and faster the determination of cell components by means of cytofluorometry. The development of flow cytometry further contributed to the importance of quantitative cytochemistry. At its beginning, the mission of flow cytometry was still DNA quantitation. For a decade the Feulgen reaction had been the reference methodology for both conventional and flow cytofluorometry; the advent of Shiff-type reagents contributed to expand the variety of possible fluorochromes excitable in the entire visible spectrum as well as in the ultraviolet region. The fluorescence scenario was progressively enriched by new probes among which are the intercalating dyes which made DNA quantitation simple and fast, thus spreading it worldwide. The final explosion of cytofluorometry was made possible by the availability of a large variety of probes directly binding DNA structure. In addition, immunofluorescence allowed to correlate the cell cycle-related DNA content to other cell markers. In the clinical application of flow cytometry, this promoted the introduction of multiparametric analyses aimed at describing the cytokinetic characteristics of a given cell subpopulation defined by a specific immunophenotype setting.

Conventional diagnostics in multiple myeloma

This paper reviews the most relevant laboratory techniques currently used for the evaluation of patients with multiple myeloma (MM) and other monoclonal gammopathies. Although the bone marrow morphological examination and electrophoretic analysis of the monoclonal paraprotein still remain the 'gold standard' techniques for fast, accurate and cost-effective diagnosis, other assays such as immunophenotyping, DNA cell content and cell cycle analysis measured by flow cytometry may contribute to a better assessment of myeloma patients. Here, we will discuss not only the contribution of each technique to differential diagnosis of monoclonal gammopathies, but also the value of each parameter as prognostic factor and for monitoring treatment efficacy. In addition, possible technical pitfalls inherent to each technique will be analysed.

Impaired bone marrow hematopoietic progenitor cell function in rheumatoid arthritis patients candidated to autologous hematopoietic stem cell transplantation

We have evaluated bone marrow morphology, percentage of bone marrow CD34(+) cells, proliferative activity of bone marrow precursors, clonogenic assay (BFU-E and CFU-GM) in short-term bone marrow cultures, and bone marrow cell apoptosis, together with serum TNF-alpha and IL-6, in 16 chronic, refractory RA patients, as well as in five healthy controls. Of 16 RA patients (68.7%), 11 showed a reduced bone marrow cellularity, while it was normal in all the controls. In RA patients, the median percentage of CD34(+) bone marrow cells, the median percentage of proliferating bone marrow myeloid precursors, and the median number of both BFU-E and CFU-GM colonies were significantly lower than observed in the controls. As far as TNF-alpha and IL-6 titers is concerned, the latter did not significantly differ from controls' values, while TNF-alpha titers were significantly lower in healthy controls. Finally, the median apoptotic index of early bone marrow myeloid cells of RA patients was significantly higher compared with controls. These observations may identify the biological risk factors for impaired mobilization and/or engraftment when RA patients are candidates for autologous hematopoietic stem cell grafting.

Response to first-line chemotherapy and long-term survival in patients with multiple myeloma: results of the MM87 prospective randomised protocol

In this study we evaluated whether a good response to conventional chemotherapy, i.e. a significant tumour reduction, is a prerequisite for improved survival in multiple myeloma (MM). Between January 1987 and March 1990, 341 consecutive previously untreated patients with MM received chemotherapy within the prospective, multicentre, randomised Protocol MM87. Of these, 258 patients were evaluable for both response and long-term survival and 244 (94.6%) have died. The median survival of all patients was 40 months (6-162 months). The median survival did not differ between patients who had complete response (CR) (50 months (9-162 months)), partial response (PR) (46 months (8-147 months)) or stable disease (SD) (41 months (7-135 months)). The median survival was shorter (13.6 months (6-135 months)) (P<0.0001) in patients whose disease progressed while they were receiving first induction chemotherapy. Causes of death were more frequently (P=0.04) related to MM in patients who had progressive disease (PD) than in patients who had a CR or PR or SD. The main clinical and laboratory characteristics were similar in the four groups. These data indicate that patients who maintain SD during first-line chemotherapy have a prognosis similar to that of patients who attain a response. Only patients whose disease progresses have a distinctly worse outcome.

High incidence of N and K-Ras activating mutations in multiple myeloma and primary plasma cell leukemia at diagnosis

Using allele-specific amplification method (ARMS), a highly sensitive one-stage allele-specific PCR, we have evaluated the incidence of NRAS and KRAS2 activating mutations (codons 12, 13, and 61) in 62 patients with either monoclonal gammopathy of undetermined significance (MGUS) or multiple myeloma (MM), primary plasma-cell leukemia (P-PCL), and also in human myeloma cell lines (HMCL). NRAS and/or KRAS2 mutations were found in 54.5% of MM at diagnosis (but in 81% at the time of relapse), in 50% of P-PCL, and in 50% of 16 HMCL. In contrast, the occurrence of such mutations was very low in MGUS and indolent MM (12.50%). Of note, KRAS2 mutations were always more frequent than NRAS. The validity of the technique was assessed by direct sequencing of cell lines and of some patients. Multiple mutations found in two patients were confirmed by subcloning exon PCR amplification products, testing clones with our method, and sequencing them. Thus, these early mutations could play a major role in the oncogenesis of MM and P-PCL.

Long-term survival of stage I multiple myeloma given chemotherapy just after diagnosis or at progression of the disease: a multicentre randomized study. Cooperative Group of Study and Treatment of Multiple Myeloma

We conducted a randomized trial to evaluate whether melphalan-prednisone (MPH-P) treatment administered just after diagnosis improves survival of stage I multiple myeloma (MM). Between January 1987 and March 1993, 145 consecutive previously untreated patients with stage I MM were randomized between treatment with MPH-P (administered for 4 days every 6 weeks) just after diagnosis and treatment only at disease progression. Survival was not influenced by MPH-P treatment either administered just after diagnosis or at disease progression (64 vs 71 months respectively). Comparing the first with the second group the odds ratio of death is 1.17 (95% confidence interval 0.57-2.42; P = 0.64). Disease progression occurred within a year in about 50% of patients who were initially untreated. Response rate was similar in both groups, but duration of response was shorter in patients who were treated at disease progression (48 vs 79 months, P = 0.044). Patients actually treated at disease progression (34/70) survived shorter than those who had neither disease progression nor treatment (56 vs > 92 months; P = 0.005). Starting MPH-P just after diagnosis does not improve survival and response rate in stage I MM, with respect to deferring therapy until disease progression. However, patients with stage I MM randomized to have treatment delayed and who actually progressed and were treated had shorter survival than those with stable disease and no treatment. Biologic or other disease features could identify these subgroups of patients.

Overexpression of the Receptor for Hyaluronan-Mediated Motility (RHAMM) Characterizes the Malignant Clone in Multiple Myeloma: Identification of Three Distinct RHAMM Variants

The receptor for hyaluronan (HA)-mediated motility (RHAMM) controls motility by malignant cells in myeloma and is abnormally expressed on the surface of most malignant B and plasma cells in blood or bone marrow (BM) of patients with multiple myeloma (MM). RHAMM cDNA was cloned and sequenced from the malignant B and plasma cells comprising the myeloma B lineage hierarchy. Three distinct RHAMM gene products, RHAMMFL, RHAMM−48, and RHAMM−147, were cloned from MM B and plasma cells. RHAMMFL was 99% homologous to the published sequence of RHAMM. RHAMM−48 and RHAMM−147 variants align with RHAMMFL, but are characterized by sequence deletions of 48 bp (16 amino acids [aa]) and 147 bp (49 aa), respectively. The relative frequency of these RHAMM transcripts in MM plasma cells was determined by cloning of reverse-transcriptase polymerase chain reaction (RT-PCR) products amplified from MM plasma cells. Of 115 randomly picked clones, 49% were RHAMMFL, 47% were RHAMM−48, and 4% were RHAMM−147. All of the detected RHAMM variants contain exon 4, which is alternatively spliced in murine RHAMM, and had only a single copy of the exon 8 repeat sequence detected in murine RHAMM. RT-PCR analysis of sorted blood or BM cells from 22 MM patients showed that overexpression of RHAMM variants is characteristic of MM B cells and BM plasma cells in all patients tested. RHAMM also appeared to be overexpressed in B lymphoma and B-chronic lymphocytic leukemia (CLL) cells. In B cells from normal donors, RHAMMFL was only weakly detectable in resting B cells from five of eight normal donors or in chronically activated B cells from three patients with Crohn’s disease. RHAMM−48 was detectable in B cells from one of eight normal donors, but was undetectable in B cells of three donors with Crohn’s disease. RHAMM−147 was undetectable in normal and Crohn’s disease B cells. In situ RT-PCR was used to determine the number of individual cells with aggregate RHAMM transcripts. For six patients, 29% of BM plasma cells and 12% of MM B cells had detectable RHAMM transcripts, while for five normal donors, only 1.2% of B cells expressed RHAMM transcripts. This work suggests that RHAMMFL, RHAMM−48, and RHAMM−147 splice variants are overexpressed in MM and other B lymphocyte malignancies relative to resting or in vivo–activated B cells, raising the possibility that RHAMM and its variants may contribute to the malignant process in B-cell malignancies such as lymphoma, CLL, and MM.

Overexpression of the Receptor for Hyaluronan-Mediated Motility (RHAMM) Characterizes the Malignant Clone in Multiple Myeloma: Identification of Three Distinct RHAMM Variants

The receptor for hyaluronan (HA)-mediated motility (RHAMM) controls motility by malignant cells in myeloma and is abnormally expressed on the surface of most malignant B and plasma cells in blood or bone marrow (BM) of patients with multiple myeloma (MM). RHAMM cDNA was cloned and sequenced from the malignant B and plasma cells comprising the myeloma B lineage hierarchy. Three distinct RHAMM gene products, RHAMMFL, RHAMM−48, and RHAMM−147, were cloned from MM B and plasma cells. RHAMMFL was 99% homologous to the published sequence of RHAMM. RHAMM−48 and RHAMM−147 variants align with RHAMMFL, but are characterized by sequence deletions of 48 bp (16 amino acids [aa]) and 147 bp (49 aa), respectively. The relative frequency of these RHAMM transcripts in MM plasma cells was determined by cloning of reverse-transcriptase polymerase chain reaction (RT-PCR) products amplified from MM plasma cells. Of 115 randomly picked clones, 49% were RHAMMFL, 47% were RHAMM−48, and 4% were RHAMM−147. All of the detected RHAMM variants contain exon 4, which is alternatively spliced in murine RHAMM, and had only a single copy of the exon 8 repeat sequence detected in murine RHAMM. RT-PCR analysis of sorted blood or BM cells from 22 MM patients showed that overexpression of RHAMM variants is characteristic of MM B cells and BM plasma cells in all patients tested. RHAMM also appeared to be overexpressed in B lymphoma and B-chronic lymphocytic leukemia (CLL) cells. In B cells from normal donors, RHAMMFL was only weakly detectable in resting B cells from five of eight normal donors or in chronically activated B cells from three patients with Crohn’s disease. RHAMM−48 was detectable in B cells from one of eight normal donors, but was undetectable in B cells of three donors with Crohn’s disease. RHAMM−147 was undetectable in normal and Crohn’s disease B cells. In situ RT-PCR was used to determine the number of individual cells with aggregate RHAMM transcripts. For six patients, 29% of BM plasma cells and 12% of MM B cells had detectable RHAMM transcripts, while for five normal donors, only 1.2% of B cells expressed RHAMM transcripts. This work suggests that RHAMMFL, RHAMM−48, and RHAMM−147 splice variants are overexpressed in MM and other B lymphocyte malignancies relative to resting or in vivo–activated B cells, raising the possibility that RHAMM and its variants may contribute to the malignant process in B-cell malignancies such as lymphoma, CLL, and MM.

DNA cell content studies in multiple myeloma

Here the current studies in cell DNA content of plasma cells (PC), from multiple myeloma (MM) patients is reviewed, focusing on two complementary aspects the detection of clonal abnormalities and the identification of the proliferative rate of PC. There is accumulating evidence that the measurement of cell DNA content by flow cytometry (FCM) is a useful parameter in the clinical evaluation of MM patients. Between 50 and 70% of MM patients display DNA aneuploidy, the majority of them being hyperdiploid. Comparing hyperdiploid with diploid patients, the former seem to display a better prognosis. Fluorescence in situ hybridization studies have confirmed that there is a high incidence of numerical chromosome abnormalities in MM and that trisomies are significantly more common than monosomies (84% vs 14%). The most frequent gains can be seen in chromosome 9 and 15 while the most common monosomies are those of chromosome 13 and X in females. The possibility of analysing the cell cycle distribution by using a propidium iodide (PI)/CD38 double staining technique may be an alternative to other more laborious methods of assessing the PC labelling index. Thus, patients with > 3% S-phase PC detected by FCM have an adverse prognosis and this parameter is one of the most important independent prognostic criteria for predicting survival in MM patients. Moreover, the number of S-phase PC, together with other prognostic factors, such as beta 2microglobulin, age and performance status can be a very useful tool for stratifying patients into groups in order to establish risk-directed therapeutic protocols.

Immunophenotype and DNA cell content in multiple myeloma

In this paper three different areas of the biology of multiple myeloma (MM) are reviewed: (1) the immunophenotypic characteristics of plasma cells (PC), (2) the changes in the immunoregulatory cells, and (3) the cell DNA content of PC. Myelomatous PC display a heterogeneous phenotype not only between different patients but also within each patient consistent with the fact that the neoplastic clone is able to undergo a certain degree of differentiation. In addition, PC generally lack surface B cell associated antigens and infrequently show reactivity for non-lineage restricted markers. The B-B4 and CD38 are the two best markers for identifying PC which are crucial for the correct assessment of other antigens by multiple staining procedures. Moreover, some of the antigens present in PC such as CD56, CD20, CD10, CD28 and SIg may have prognostic implications. Whether or not normal PC are phenotypically different from myelomatous PC remains controversial although some antigenic combinations such as CD19-/CD56++ could probably help to identify the malignant nature of PC. Both T and NK cells are markedly altered in MM patients probably reflecting a host-tumour immunological interaction. The reduction in CD4 cells correlates both with advanced clinical stage and poor survival. As far as NK cells are concerned, there is an overall increase in peripheral blood and BM in MM patients but the changes observed are heterogeneous, reflecting the existence of different NK cell subsets. This fact could explain the contradictory results observed in the literature. Accumulating evidence exists that the measurement of cell DNA content by flow cytometry is a useful parameter in the clinical evaluation of MM patients. Between 50 and 70% of MM patients display DNA aneuploidy with the majority of them hyperdiploid. Upon comparing hyperdiploid with diploid patients, the former usually display a better prognosis. The possibility of analysing the cell cycle distribution by using a PI/CD38 double staining technique may be an alternative to other more laborious methods of assessing the PC labelling index. In our experience, patients with > 3% S phase PC have an adverse prognosis and this parameter was the most important independent prognostic criteria for predicting survival.

Cell kinetics of CD34-positive hematopoietic cells following chemotherapy plus colony-stimulating factors in advanced breast cancer

Bone-marrow (BM) hematopoietic precursors are recruited into proliferative activity when colony-stimulating factors (CSF) are sequenced with chemotherapy (CT). Previous studies suggested that further CT can be safely administered only when the increased proliferative activity of these cells has subsided, because most cytostatic drugs selectively damage cycling cells. The safest interval between CSF discontinuation and the start of the next CT course needs to be ascertained in vivo. Thirty patients with advanced breast cancer were treated with an intensified FEC regimen, planned at 21-day intervals, sequenced with granulocyte-macrophage (GM)-CSF (15 patients) or granulocyte (G)-CSF (15 patients). Using flow cytometry (FCM) we evaluated the proliferation kinetics of CD34+ BM hematopoietic progenitors before CT+CSF and at different times after CSF administration was stopped. FEC+GM- and FEC+G-CSF sequences both induced a rapid and sustained increase in the percentage of BM myeloid precursors (BMMP%) and in the cycling status of CD34+BM cells. However, while the BMMP% remained elevated in both cases after CSF were stopped, the enhanced proliferative activity of CD34+ cells decreased more rapidly after GM- than after G-CSF. Using FCM, CD34+ BM-derived hematopoietic presursor cell kinetics is readily evaluated in the clinical setting. The administration of CSF following CT increases both the proliferative activity of CD34+ BM cells and the BMMP%. After CSF were discontinued a kinetic refractoriness of hematopoietic progenitors was more evident after GM-CSF than after G-CSF. These data may be of value in designing clinical trials to avoid cytostatic damage to the BM hematopoietic stem-cell compartment.

Prognostic implications of DNA aneuploidy in 156 untreated multiple myeloma patients. Castelano-Leonés (Spain) Cooperative Group for the Study of Monoclonal Gammopathies

In this study the incidence of DNA aneuploidy in a large series of untreated multiple myeloma (MM) patients was assessed in order to determine its clinical and prognostic significance. A total of 156 MM patients were included in the study. DNA measurements were performed in all cases at diagnosis using two different flow cytometry methods: (1) propidium iodide (PI) staining on isolated nuclei, and (2) CD38/PI double staining on whole cells. The DNA ploidy status was correlated with the most relevant clinical and haematological disease characteristics. From the 156 cases analysed, 91 (58%) were aneuploid (56% hyperdiploid and 2% hypodiploid). The correlation between the two techniques on the detection of DNA aneuploidy was excellent, although CD38/PI double staining would be preferable in cases with < 5% of DNA aneuploid plasma cells (PC). Upon comparing the clinical and haematological disease characteristics of hyperdiploid versus diploid cases, the former group was characterized by a lower age, reduced incidence of anaemia, lower beta 2M levels, higher proliferative activity within the residual normal haemopoietic cells, increased expression of CD56 antigen in PC, and higher proportion of PB CD4+ T cells. In contrast, diploid cases had a higher expression of the CD10, CD20 and CD15 antigens and greater numbers of PB CD56+CD3- NK cells (P < 0.05). Circulating PC were identified in six cases, all being diploid. Overall survival was significantly longer in hyperdiploid compared to diploid MM (P = 0.02). These results show that over 50% of MM patients are aneuploid, almost all of them being hyperdiploid. This characteristic is associated with better prognosis.

The proliferation of multiple myeloma colonies (MY-CFUc) in vitro is independent of prognosis and is not associated with mutated N- or K-ras alleles in human bone marrow aspirates

During the period September 1987 to March 1993 the proliferation of myeloma cells as colonies (MY-CFUc) in vitro was examined in bone marrow aspirates from 43 patients with multiple myeloma and two patients with Waldenström's macroglobulinaemia. Twenty-four samples from 45 patients, of whom three were at presentation, four were in complete remission (CR), six had achieved a partial response (PR) and 11 had progressive disease (PD), produced MY-CFUc in vitro. The same bone marrow aspirates or one taken within 2 months of that assessed for MY-CFUc were used in the polymerase chain reaction (PCR). Genomic DNA was analysed for mutations in N- and K-ras by slot blotting of the amplified products from the PCR with 32P-labelled probes and by direct sequencing. No mutations were detected in N- or K-ras proto-oncogenes at codons 12, 13 or 61 in any sample. Eleven of the patients from whom MY-CFUc were produced remain alive with a median survival of 73 months (range 15-75 months). MY-CFUc have been cultured from 19 of these 24 patients on subsequent occasions, of whom nine remain alive. Among patients whose cells did not produce MY-CFUc in vitro at the time of sampling for mutated ras alleles, biopsy samples from four patients have produced MY-CFUc in vitro on subsequent occasions, of whom one patient remains alive. The data show that the proliferation of MY-CFUc in vitro occurred independently of disease status and was not indicative of prognosis. The failure to detect mutated N- or K-ras alleles in any sample suggests that if such mutations were present in the cells which form colonies in vitro they represented less than 0.1% of the tumour burden and did not affect the survival of this group of patients.

Prognosis in myeloma

OBJECTIVE

To review biologic factors that may be useful in determining prognosis in patients with myeloma.

DESIGN

The currently available clinical variables and staging systems were assessed for their predictive value in myeloma, and newly proposed prognostic factors were summarized.

RESULTS

Because some patients with myeloma may potentially benefit by new, more intensive therapies such as stem cell transplantation or may have prolonged survival with standard therapy, determining factors that would distinguish such patients is important. Independent prognostic factors such as the plasma cell labeling index and beta 2-microglobulin have repeatedly outperformed other prognostic clinical variables and can be combined into a system that identifies poor, intermediate, and good prognostic groups of patients with myeloma. New factors are needed to improve on the predictive value of these two variables. Studies of the biologic features of myelomas have led to the discovery of soluble interleukin 6 receptor (sIL 6R) in the serum. sIL 6R enhances the myeloma cell response to interleukin 6, a central growth factor that affects myeloma cell proliferation. Preliminary studies by the Eastern Cooperative Oncology Group show that sIL 6R predicts survival independent of the plasma cell labeling index and beta 2-microglobulin. Other proposed independent prognostic factors include cytokines and their soluble receptors, regulatory T cells, circulating myeloma cells, myeloma cell precursors, and markers of proliferation, apoptosis, and drug resistance.

CONCLUSION

Because of wide variation in duration of survival, the prognosis of patients with myeloma, a fatal bone marrow plasma cell neoplasm, cannot yet be adequately predicted. Better prognostic factors are needed for stratification in clinical trials, counseling of patients, and designing of new therapeutic trials.

RHAMM, a receptor for hyaluronan-mediated motility, on normal human lymphocytes, thymocytes and malignant B cells: a mediator in B cell malignancy?

RHAMM (Receptor for HA Mediated Motility) is a novel HA receptor that has been linked to regulating cell locomotion and density dependent contact inhibition of fibroblasts, smooth muscle cells, macrophages, lymphocytes, astrocytes and sperm. The ubiquitous expression of RHAMM suggests the existence of multiple isoforms, and indeed, RHAMM is found in various cellular compartments, namely nuclear, cytosolic, membrane-bound and extracellular. In this review, we emphasize the evolving role of RHAMM in B cell malignancies, and examine the function of RHAMM in T cell development in the thymic microenvironment. Both the motile behaviour of progenitor thymocytes (CD3-CD4-CD8-) and malignant B cells from multiple myeloma (MM), plasma cell leukemia, and hairy cell leukemia was blocked by monoclonal antibodies to RHAMM, suggesting that motility may correlate with increased expression of RHAMM at the cell surface. Interestingly, the soluble form of RHAMM is able to inhibit fibroblast locomotion, and it is likely that a balance between expression of both forms determines, in part the motility of cells. RHAMM appears to play a fundamental role in the immune system and the ability of RHAMM to function as a motility receptor is likely to be due to complex variables including the extent to which soluble RHAMM is secreted. RHAMM expression characterizes circulating monoclonal B cells as abnormal. potentially invasive and/or metastatic components of myeloma and may underlie the malignant behavior of these cells.

Multistep transformation in low-grade lymphoproliferative diseases

BACKGROUND

Carcinogenesis, the formation of solid tumors, is now widely accepted to represent a multistep process. Several genetic events, activation of proto-oncogenes and inactivation of tumor suppressor genes, are involved.

DESIGN

Review of the literature for evidence that the concept of multistep transformation has relevance also for the formation of low-grade lymphoproliferative diseases.

RESULTS AND CONCLUSION

The common translocations in low-grade lymphoid tumors are probably early events, predominantly involved in the activation of oncogenes, leading to growth stimulation or prolonged cell survival. As a result 'monoclonal lymphoproliferative disorders of undetermined significance (MLDUS)' occur, undetermined, because some translocations may not always led to tumor formation. For progression to full malignancy, additional genetic events are required besides sequential selection of variant subpopulations within the neoplastic clone. Recent data indicate that mutations and deletions of putative tumor suppressor genes, including the P53 and retinoblastoma genes, are also involved in the progression of lymphoproliferative disorders. A list of lymphoproliferative diseases stressing this concept of multistep transformation is presented in this article.

Bone marrow myeloid cell kinetics during treatment of small cell carcinoma of the lung with chemotherapy not associated and associated with granulocyte-macrophage colony-stimulating factor

Information on the kinetics of bone marrow (BM) myeloid precursors (BMMP) is required for integrating cancer chemotherapy with granulocyte-macrophage colony-stimulating factor (rhGM-CSF), with the aim of reducing neutropenia. Using bivariate flow-cytometric analysis of the in vivo incorporation of bromode-oxyuridine (BUDR) vs DNA content we have studied the kinetics of BMMP in 21 patients with SCLC during the first of six chemotherapy courses (etoposide, epirubicin, and cis-platinum, days 1-3, every 21 days), given alone (eight patients) or followed by rhGM-CSF (10 micrograms/kg/day s.c., days 4-14) as BM rescue (eight patients) or both preceded (days -17 to -7, as BM priming) and followed by rhGM-CSF (five patients). At 11-14 days after the start of these therapies there was an increase in the baseline proliferative activity of proliferating BMMP and a shortening in the time needed by the metamyelocyte to mature and to leave the marrow. Both effects were greater and were maintained to a significantly greater degree a week later in patients who received chemotherapy plus rhGM-CSF rescue than in those who received chemotherapy alone or rhGM-CSF priming alone. At day 11-14 the pretreatment median cell production rate of pBMMP was increased by 340%, 150%, and 183% and the maturation time was reduced by 80%, 45%, and 57%, respectively, in the three groups. A week later, the corresponding figures were 206%, 111%, and 157% and 50%, 18%, and 45%. Hence, an identical rhGM-CSF schedule is more effective in increasing the neutrophil production by BMMP when given following chemotherapy as BM rescue than before it as BM priming. In both the rescue and the priming schedule, the increase in proliferative activity of BMMP just at the end of rhGM-CSF stimulation was linked to both an increase in the labeling index and a reduction in duration of S-phase (TS), while a week later it was linked solely to reduction in TS. This could actually reduce one of the two kinetic targets of subsequently administered cytostatics, i.e., a high LI and a long time spent in S phase. From this study, accurate kinetic data can be obtained with the in vivo BUDR technique that are useful in scheduling rhGM-CSF.

ras p21 expression in relation to DNA ploidy, S-phase fraction and prognosis in colorectal adenocarcinoma

ras p21 expression, as indicated by the monoclonal antibody ras 11, was estimated using immunohistochemistry on 69 primary colorectal adenocarcinomas. Also, DNA ploidy and S-phase fraction (SPF) were analysed with flow cytometry. Positive staining for ras 11 tended to be more common in DNA non-diploid tumours (P = 0.11), but was significantly correlated with high SPF (P = 0.038). Positive ras 11 staining, Dukes' stage, DNA ploidy and SPF were related to the recurrence-free interval of patients with Dukes' A-C tumours (P = 0.0014, P = 0.023, P = 0.035 and P = 0.040, respectively). ras 11 staining was a prognostic factor independent of both Dukes' stage and DNA ploidy (P = 0.011). The results indicate that pan ras p21 expression is associated with proliferative activity and has an independent prognostic value in colorectal adenocarcinoma.