A new human hepatocellular carcinoma cell line (HAK-2) forms various structures in collagen gel matrices.

We established a new human hepatocellular carcinoma (HCC) cell line, designated HAK-2, from a surgically resected HCC of a 57-yr-old Japanese man. The patient's tumor consisted of 5 different histological features in a single nodule: well-differentiated HCC with trabecular pattern; and moderately differentiated HCC with 4 different patterns (i.e., trabecular, pseudoglandular, solid, and scirrhous). Morphologically, HAK-2 cells on a plastic dish showed oval-shaped nuclei and large flat, polygonal eosinophilic cytoplasm and proliferated in a monolayered sheet with a population doubling time of 36.8 hours. Meanwhile, various structures, such as compact, trabecular, and tubular arrangements, were induced in HAK-2 cells cultured in type I collagen gel matrix. Also, HAK-2 cells in vitro underwent spontaneous apoptosis more frequently than other HCC cell lines examined. HAK-2 cells secreted various plasma proteins including albumin into the culture medium. Chromosome and flow cytometric analyses revealed that HAK-2 had many structural abnormalities with human karyotype and a single aneuploid cell population with a DNA index of 3.7, respectively. These findings suggest that HAK-2 is a new human HCC cell line representing two morphological characteristics; (1) formation of various structures in the presence of extracellular matrix and (2) frequent spontaneous apoptosis in vitro.