Establishment and Characterization of New Murine Breast Cancer Cell Lines

Abstract

The establishment of two new breast cancer cell lines, MXT+ and MXT−, derived from the murine breast cancer models MXT‐M‐3, 2 MC (hormone‐sensitive) and MXT‐M‐3, 2 (ovex) MC (hormone‐insensitive), is described. Characterization of the cell lines was performed by investigation of morphology, steroid hormone receptor state, growth kinetics, and drug response as well as by cytogenetic analysis. MXT+ contains estrogen receptors (ER; 6.9 fmol/mg protein) as well as progesterone receptors (PgR; 9.2 fmol/mg protein) and therefore is inhibited by tamoxifen (Tam). MXT− proved to be ER− but PgR+ (23.4 fmol/mg protein) and, as expected, resistant against Tam.The sensitivity of MXT+ and MXT− against a pattern of therapeutically established anti‐breast cancer drugs (cDDP, cisplatin; JM‐8, carboplatin; DX, adriamycin; 5‐FU, 5‐fluorouracil; MTX, methotrexate; VLB vinblastine) was studied by use of a computerized, kinetic chemosensitivity assay based on quantification of biomass by staining cells with crystal violet. For each compound the inhibition profile reflecting cytostatic, transient cytotoxic, or cytocidal drug effects as well as development of resistance was evaluated. The following order of activity was found: MTX >, VLB ≥ DX > cDDP ≥ 5‐FU > JM‐8. The test data of 5‐FU, VLB, cDDP, and Tam on MXT+ as well as on MXT− were compared with those from studies on ER+ and ER− human breast cancer cell lines (MCF‐7, ZR‐75‐1, T‐47‐D, and MDA‐MB‐231, respectively). They revealed comparable inhibition profiles and sensitivities of human and murine breast cancer cell lines, an indication that the results achieved in combined in vitro‐/in vivo tests by use of the murine test models MXT+, MXT−, MXT‐M‐3, 2 MC, and MXT‐M‐3, 2(ovex) MC are relevant for therapy in humans.

Roles of hormone replacement therapy and iron in proliferation of breast epithelial cells with different estrogen and progesterone receptor status

“…PR levels were previously shown to be similar between MXT + and MXT − cells. 23 Prempro™ increased proliferation of ER + /PR + MXT + cells but not ER − /PR + MXT − cells at 24 h treatment (Fig. 2).…”

“…22 MXT + cells with ER + /PR + and MXT − cells (ER − /PR + ) were previously characterized. 23 All cells were initially cultured in α-MEM containing 10% FBS and 0.9 mg/ml L-glutamine in a humidified atmosphere of 95% air, 5% CO 2 at 37 °C and changed to 0.1% FBS as indicated in the figure legends for treatments.…”

“…The effects of chemical reagents on cell proliferation were calculated as follows 23 Water-soluble E2, Pg, and Fe as ferrous sulfate were all freshly prepared in distilled water at high concentrations except Tam in methanol and further diluted in α-MEM before MCF-7 cell treatment. The selected doses for the testing were relevant to pharmacological doses during HRT use.…”

Synthesis and characterisation of estrogenic carriers for cytotoxic Pt(ii) fragments: biological activity of the resulting complexes

“…48 As far as non-hormonal Pt(II) complexes are concerned, the cytotoxic effect of cis-[Pt(en)Cl 2 ], cis-[Pt(NH 3 ) 2 mal], and cisplatin is lower for MDA-MB-231 with respect to that of the MCF-7 cell line, as previously reported in the literature. 49 Returning to the question of viability of the MCF-7 cell line, it is disappointing that complexes 7 and 8 showed no advantage in terms of inhibition of proliferation over the corresponding model complexes cis-[Pt(en)Cl 2 ], cis-[Pt(NH 3 ) 2 mal] or cisplatin itself. This failure might be attributable to several factors: i) the decrease in cytotoxicity due to the steric effect of chelating arms necessary for linking the Pt(II)-moiety to the estrogen; 6 ii) the isomerisation from (O,O ) to (N,O)-chelate forms in 8; iii) the limited number of receptors able to act as a shuttle for the estrogen-platinum intracellular adduct (see bio-stoichiometry in the experimental section) and iv) most importantly, the estrogenic (agonistic) activity of the overall assembly.…”

Hormone Replacement Therapy, Iron, and Breast Cancer

“…Therefore, iron may be an important etiological factor in the development of breast cancer in post-menopausal women. In the present study, we (17). All cells were cultured in α-MEM containing 10% FBS and 0.9 mg/ml Lglutamine in a humidified atmosphere of 95% air, 5% CO 2 at 37 o C. Figure 1 shows the ER status of the four cell lines used, which confirmed their differences in ER levels and, thus, provide a useful tool for the present study.…”