Karyotype evolution in a simian virus 40-transformed tumorigenic human cell line

Area of Science:

• Cell Biology
• Genetics
• Oncology

Background:

• Normal human foreskin fibroblasts (HSF4) were utilized to investigate cellular transformation.
• The pSV3-neo plasmid was employed for transfection to induce genetic alterations.

Purpose of the Study:

• To characterize the in vitro transformation and immortalization of human fibroblasts.
• To analyze the cytogenetic changes associated with tumor formation and progression in vivo.
• To understand the genetic instability driving cancer development.

Main Methods:

• Transfection of HSF4 cells with pSV3-neo plasmid.
• In vitro culture and G418 selection to obtain resistant colonies (HSF4-T12).
• Subcutaneous injection into nude mice, including implantation in Gelfoam sponges.
• Flow karyotype and G-banded chromosomal analysis of cell lines and tumors.

Main Results:

• HSF4-T12 cells exhibited progressive transformation markers and immortalization.
• Tumor formation occurred in mice when cells were injected into Gelfoam sponges, with subsequent rapid tumor development upon re-injection.
• Cytogenetic analysis revealed distinct phases of chromosomal changes, including early random alterations and later stable clonal rearrangements (e.g., t(2;4), 6p-, -Y).
• Tumor analysis showed loss of chromosomal material, specifically 6q, 13, 15, 20, and Y.

Conclusions:

• Immortalized human fibroblasts can acquire tumor-forming capabilities under specific conditions.
• Tumorigenesis is associated with significant chromosomal instability, including both balanced rearrangements and chromosomal losses.
• The study provides insights into the genetic events driving fibroblast transformation and tumor progression.