Long noncoding RNA ROR promotes proliferation and invasion of colorectal cancer by inhibiting tumor suppressor gene NF2 through interacting with miR-223-3p.

OBJECTIVE: Colorectal cancer is one of the most common cancers in the world. LncRNA ROR, is a tumor oncogene associated with various human cancers. However, the role of ROR in colorectal cancer cells still remains unknown. The aim of this study was to measure the expression level of ROR and clarify its biological functions in colorectal cancer cells. MATERIALS AND METHODS: The expression level of ROR in colorectal cancer cells was detected using qRT-PCR. We performed CCK8 assay, colony formation assay, cell migration and invasion assays to evaluate the effects of ROR on cell proliferation, migration and invasion of colorectal cancer cells. Then, transfection of ROR, ROR inhibitor, miRNA-223-3p-mimics and miRNA-223-3p-inhibitor, qRT-PCR, and luciferase reporter assay were used to explore the molecular mechanisms. RESULTS: In the present study, Lnc-ROR was highly expressed in colorectal cancers compared with adjacent non-cancerous normal tissues. And the expression level of ROR was also increased in colorectal cancer cells (p < 0.05). CCK8 assay and invasion assay suggested that ROR can promote cell proliferation and invasion. The luciferase reporter assay showed ROR acted as sponge and directly competed with miRNA-223-3p, then decreasing the expression of tumor suppressor gene NF2. CONCLUSIONS: The findings of this study first revealed that ROR was upregulated in colorectal cancer cells and can promote cell proliferation and invasion by inhibiting tumor suppressor gene NF2 through interacting with miR-223-3p.

Studies on mechanisms and blockade of carcinogenic action of female sex hormones.

Tumours of mice are induced by administration of Inj. Hydroxyprogesteroni Caproatis Co. (EP) in a practical subthreshold dose of carcinogenesis or 2.5-5 times the human contraceptive dose (simply referred to as 2.5- to 5-fold dose) combined with whole-body 0.5 Gy gamma-ray irradiation. Malignant transformation of Syrian golden hamster embryo (SHE) cells is also induced by 5-fold dose of EP combined with 0.3 Gy gamma-ray irradiation in vitro, thereby indicating that synergistic carcinogenesis can be obtained by combined use of physical and chemical carcinogens. The mechanisms of synergistic carcinogenesis have been further explained by cytogenetics, damage extent of the target cell DNA and production of free radicals. The Chinese traditional medicine with antioxidating effect (Sulekang Capsule, SC), food additive--butylated hydroxyanisole (BHA) and green tea can effectively inhibit the carcinogenic effect of EP or EP combined with gamma rays in mice. They all have marked ability to scavenge or remove the free radicals and thereby reduce the DNA damage.

Experimental studies on the late effects of female sex hormones.

Inj. Hydroxyprogesterone Co. (EP) was injected i.m. into female Wistar rats, different strains of mice of both sex and Syrian golden hamsters with doses of 5-100 times the human contraceptive dose once or twice a month for 10-32 times. In some experiments EP was combined with whole-body 3 Gy gamma ray radiation once or twice. Results show that EP has obvious carcinogenicity and can enhance the gamma ray carcinogenicity, thereby increasing the tumor incidence or the ratio of malignant to benign tumours. Carcinogenic mechanisms of EP have also been studied.

[Therapeutic mechanisms and effects of urea in treating mouse transplantable hepatocellular carcinoma].

In this paper, mouse transplantable hepatocellular carcinomas of both solid and ascitic types were effectively treated by urea. Survival time of tumour-bearing animals was obviously prolonged. Tumour cells in the treated group were significant swelling, degeneration, necrosis, smoothing of cellular surface and loss of infiltrating ability to surrounding soft tissues observed by light, electron and scanning electron microscope. As assayed by cellular kinetics and autoradiography, proliferation was inhibited, appearing as decrease of mitotic index and prolongation of cell cycle time, and so on. The proliferating ability of tumour stem cells in the treated group was severely inhibited as tested by colony formation frequency in soft-agar medium. There was no obvious alteration in relative DNA content in tumour cells or in the ratio of number of cells in various phases to cell population according to the assay of fluorescence activated cell sorter. This means that urea is a cell cycle non-specific antitumour agent and is able to kill tumour cells in various phases.

Establishment and biological properties of mouse granulocytic leukemic cell line-L833.

A granulocytic leukemic cell line, called L833 has been established through culturing in vitro from mouse bone marrow of transplantable granulocytic leukemia. More than 280 passages have been performed in 3 years. Cell growth has been rapid and stable. Incidence of tumour formation was 100% with various routes of inoculation. The nature of granulocytic leukemia was confirmed by examination of cytology, cytochemistry, pathology and ultrastructural changes. Analysis proved chromosomes to be hypodiploid with model number of 39, loss of chromosomes, and presence of a marker. Besides the chromosomal change as mentioned above, both L883-A and L833-B derived from colonies formed from the L833 cells cultured in semi-solid agar medium, have their own marker. The cell line was sensitive to various types of antitumour agents in varying degrees. It was also sensitive to ionizing radiation. D0 values of L833 and L883-A cells were 98.8 and 104.9 rad, respectively. The results were similar to that of L801. Establishment of this cell line is of important significance for studying leukemia and screening anti-tumour agents, as well as provides a useful direct, economic and precisely quantitative tool for other relative studies.

[In vitro studies of the cell cycle of mouse myelomonocytic leukemia using a fluorescence activated cell sorter and autoradiography].

Cell cycle and various phase time of mouse myelomonocytic leukemia cells were studied in vitro with Fluorescence Activated Cell Sorter (FACS 420, Becton-Dikinson FACS Systems, Sunnyvale, CA, USA) in testing cellular DNA content and with autoradiography. At the same time, doubling time was calculated by counting the number of cells cultured in vitro within 6 days following implantation. According to the cellular DNA content, the proportions of various cell phases in the whole cell population were as follows: G1, S and G2 plus M phases take up 30.5%, 47.9% and 21.6%. Basing on autoradiography and direct counting, the cell number, the cell cycle, duration of various cell phases and doubling time were as follows: LI = 98.0%, MI = 1.7 +/- 0.9%, TG1 = 4.9 hrs, TS = 8.0 hrs, TG2 = 2.8 hrs, Tm = 0.3 hr, TC = 16.0 hrs, TD = 17.0 hrs. FACS assay showed that the duration of various cell phases are quite similar to that calculated by autoradiography. Therefore a simple and rapid FACS method may be widely used in the studies of cell cycle instead of autoradiography if estimating computer program is available.

Study on late effects of radioiodine on rats.

This paper describes the results observed on 850 male Wistar rats for two years after intraperitoneal injection with 131I, 132I or 125I of different radioactivities. The incidence of thyroid malignant tumor was 45.8% when the dose absorbed by the thyroid gland was 7.8 Gy in the 131I groups, and even tumors of lung and soft tissue, and malfunction of kidney and immune organs could be elicited when the radioiodine was overdosed. Both 132I and 125I have their optimal carcinogenic dose ranges and optimal doses of carcinogenesis. As the dosage decreases to a certain level, a low-limit dose incapable of inducing cancers may be present. 131I induced mainly papillary and mixed type carcinomas, 132I chiefly follicular and undifferentiated type carcinomas, while 125I induced follicular and medullary carcinomas. The paper also discusses cytochemical DNA quantitative assays of different histological types of thyroid gland carcinomas, holding that reference to such data as decreasing serum T4, elevating serum TSH and CIC may be helpful for early diagnosis of thyroid carcinomas.

[Malignant transformation of mouse embryo cells by estrogenic hormones in vitro].

Mouse embryo cells (MEC) taken from a LACA pregnant female mouse, were cultured in RPMI 1640 medium with 20% horse serum. In the experimental group (10 bottles), the first 3 generations of MEC were treated with estradiol valerate (E) and hydroxyprogesterone caproate (P) at doses of 5.2 micrograms/ml and 261 micrograms/ml medium in the original and the 2nd generations, and at double doses in the 1st generation. In the control group (10 bottles), the MEC were cultured without E and P. The MEC in both groups was subdivided into 3 bottles from 1 every seven days. In the experimental group (44 bottles), the morphological transformation emerged in 2 bottles of MEC (the 5th and 7th generations) after 79 day's treatment by E and P. Meanwhile, the nonmorphological transformed cells (the 3rd, 5th and 7th generations) had the ability to grow in ouabain-contained medium (Anti-Oua+). It implies that the mutation had already occurred before transformation. The transformed cells had the ability to form colonies in soft-agar medium, could be agglutinated by concanavalin A and form fibrosarcoma in the subcutaneous region after inoculation. Basing on the above results, we suggest that E and P directly act as a carcinogen on the MEC and cause the latter to undergo malignant transformation.

[Malignant transformation of mouse bone marrow cells induced in vitro by 60Co gamma-ray irradiation].

Mouse bone marrow cells were irradiated in vitro with 300, 200 and 100 rad of 60Co gamma-ray. Morphological transformation ensued from day 42 after exposure, but only in cells receiving 300 rad. Malignant transformation appeared in the 2nd generation in the subcultures. Some biological characteristics of malignant transformation were observed as follows: The attaching rate was 40.0%. Malignant transformation rate was 0.10-0.45%; Some colonies and clusters were formed in the semi-solid agar medium; There was no cell proliferation or colony formation in anti-ouabain inhibition test which implies that no mutation took place in the malignant transformation cells; Cytochalasin B rendered the cells to form a large number of multinuclear cells; Obvious chromosome aberration in number and structure was observed; Subsequent induction of fibrosarcomas in sites of subcutaneous inoculation of the malignant transformed cells in immunosuppressed mice. The results show that mouse bone marrow mesenchymal cells can undergo malignant transformation by large dose of gamma-ray irradiation in vitro. Criteria of malignant transformation: some clusters of cells formed in the semi-solid agar medium, multinuclear cell formation by action of cytochalasin B, and tumor mass induced in the location of inoculation.

Establishment of a model of transplantable myelocytic leukemia (L801) in LACA mice.

A transplantable myelocytic leukemia model of LACA mice, designated by the name of L801, was established by intravenous injection of spleen cell suspension from mice with radiation-induced myelocytic leukemia into mice of the same strain. Until now, for more than three years, the L801 has maintained stable and rapid growth and has been reproduced for over 130 serial passages. The incidence of leukemia in inoculated animals was approximately 100% and mean survival time was 10.9 +/- 2.1 days. The L801 is of myelocytic type which has been determined by cytological, cytochemical, pathological and ultrastructural observations. Its karyotype was hypodiploid, characterized by modal number of 39, loss of Y chromosome and an abnormal huge marker chromosome. The cell cycle duration of the L801 was 16 h. C-type viral particles were observed under the electron-microscope. The L801 was sensitive, to varying extents, to various anti-tumor agents. We presume that the L801 is a useful tool in studies on mechanism of leukemogenesis, anti-tumor agent screening and treatment of experimental tumors.