Non-random chromosome changes in human cancer

Cancer evolution: A means by which tumors evade treatment

Although various methods have been tried to study and treat cancer, the cancer remains a major challenge for human medicine today. One important reason for this is the presence of cancer evolution. Cancer evolution is a process in which tumor cells adapt to the external environment, which can suppress the human immune system's ability to recognize and attack tumors, and also reduce the reproducibility of cancer research. Among them, heterogeneity of the tumor provides intrinsic motivation for this process. Recently, with the development of related technologies such as liquid biopsy, more and more knowledge about cancer evolution has been gained and interest in this topic has also increased. Therefore, starting from the causes of tumorigenesis, this paper introduces several tumorigenesis processes and pathways, as well as treatment options for different targets.

Diagnostic and prognostic importance of chromosomal aberrations identified in 61 dogs with lymphosarcoma

To determine the diagnostic and/or prognostic importance of chromosomal aberrations identified in dogs with malignant (non-Hodgkin's) lymphoma, clinical stages for 61 dogs with lymphosarcoma were determined, the lymph node(s) were histopathologically graded, and the malignant tissue lymphocytes were karyotyped. The results from life table survival curve analysis demonstrated that first remission length and survival time were significantly longer in 15 of 61 (25%) dogs that had a trisomy of chromosome 13 as the primary chromosomal aberration than in those dogs (46/61, 75%) with other primary chromosomal aberrations (P < 0.05). Sex, age, weight, histopathologic subtype and grade, World Health Organization (WHO) clinical stage, WHO and modified Karnofsky performance status, chromosomal modal number, and treatment protocol were of no prognostic importance in predicting first remission length or survival time (P > 0.05). Multivariate analysis did not identify a significant correlation between the prognostic groups or within the various prognostic subsets (P > 0.05). The pathogenesis of canine and human non-Hodgkin's lymphoma, as observed cytogenetically, differs.

Chromosomal analysis of neuroblastoma

Ten children with abdominal neuroblastoma were included in the study. Biopsies from the neuroblastomas were taken during surgical operations, nine from the primary tumours and one from a metastasis. Histopathology was done for diagnosis. Chromosomal cultures of neuroblastoma cells and peripheral blood lymphocytes were performed. The peripheral blood lymphocytes revealed normal chromosomal complements. The 10 tumours were in the peridiploid range with random gains or losses of chromosomes. Deletion of the short arm of chromosome number 1 distal to band p31 occurred in 6 tumours. Other structural changes and giant markers were found. It was concluded that a regulatory gene controlling the transformation gene of neuroblastoma, is present at or distal to lp31.

Tumor cell karyotypes in malignant melanoma

Fifteen malignant melanomas were subjected to chromosomal analysis, in order to determine whether the number of chromosomes in a tumor cell could be correlated to a clinical prognosis. The protocol involved a direct technique which utilized a Colcemid blockade of spindle formation in mitosis to allow study of metaphase chromosomes. The direct method was chosen to reveal chromosome changes in the tumor cell in situ rather than changes in the cultured cell. Two tumors yielded chromosome spreads which could be counted and correlated with a clinical prognosis. Failure to obtain other adequate chromosome spreads were accounted for by the presence of tissue necrosis and the absence of viable tumor cells.

Chromosomal aberrations in human neuroblastomas

Six human neuroblastomas were analyzed by Giemsa and fluorescence banding techniques to identify chromosomal aberrations. Two neuroblastomas were primary tumors from untreated children, and four were well lines established from human neuroblastomas. Five of the six tumors studied were diploid or near diploid; one was near tetraploid. A 1p- was found in three of the neuroblastomas examined. The 1p-was present in both primary tumors, and in one it was the only abnormality detected. This deletion was also found in the cells of an established line, in addition to other abnormalities. Giant markers of different origins were found in the four cell lines, and no double-minute chromosomes were found in the primaries or the cell lines studied. Thus, a 1p-deletion was the most consistent abnormality found in the six human neuroblastomas examined in this study. We attempt to correlate this finding with Knudson's hypothesis on the origin of childhood cancer. Additional studies of primary tumors should clarify whether this specific chromosomal abnormality is related to the the acquisition of malignant behavior in human neuroblastomas.

Chromosomal aberrations in human neuroblastomas

Six human neuroblastomas were analyzed by Giemsa and fluorescence banding techniques to identify chromosomal aberrations. Two neuroblastomas were primary tumors from untreated children, and four were well lines established from human neuroblastomas. Five of the six tumors studied were diploid or near diploid; one was near tetraploid. A 1p- was found in three of the neuroblastomas examined. The 1p-was present in both primary tumors, and in one it was the only abnormality detected. This deletion was also found in the cells of an established line, in addition to other abnormalities. Giant markers of different origins were found in the four cell lines, and no double-minute chromosomes were found in the primaries or the cell lines studied. Thus, a 1p-deletion was the most consistent abnormality found in the six human neuroblastomas examined in this study. We attempt to correlate this finding with Knudson's hypothesis on the origin of childhood cancer. Additional studies of primary tumors should clarify whether this specific chromosomal abnormality is related to the the acquisition of malignant behavior in human neuroblastomas.

Some mechanisms operative in carcinogenesis a review

Multiple factors contribute to the development of neoplasia. Sometimes a single agency can bring about a tumour if it has many different effects, but at other times a tumour arises more insidiously due to a succession of events [240,241] which by themselves may be innocent. Alterations in the genome of the cell are at the fore-front of our interest because they can be brought about by most of the carcinogenic agents we know. The cell can repair some such alterations but both forward and destructive mutations do appear. The roles of cell proliferation, cell differentiation, the immune mechanism and carcinogen-activating enzymes are beginning to be understood. The effects of dose, route of administration, and of other agents given at the same time [242-245] must not be lost sight of. Other factors no doubt will be added as we begin to look at the structure and function of cell-surface membranes [246-248], at host susceptibility genetics [26, 249], and at the generation of carcinogens inside the body [250,251]. We are only beginning to understand carcinogenesis. In no single instance do we as yet know how a tumour comes about in full details of molecular biology. It is possible that fully rational treatment of cancer will not be possible until we have such an understanding. Once a tumour becomes independent of carcinogenic factors, it continues to develop in a bizarre fashion which makes its study and treatment by all means other than surgery difficult.