Amplification, rearrangement, and elevated expression of c‐myc in the human prostatic carcinoma cell line LNCaP

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Abstract
We have investigated the structure and expression of the c‐myc proto‐oncogene in DNA isolated from the immortal cell line LNCaP. This cell line was derived from a lymph node metastasis of human prostate cancer. Msp I digest of LNCaP DNA when hybridized to a human c‐myc probe showed a 1.45 kb band of intensity about two‐fold greater than that observed in normal lymphocytes. In addition, the LNCaP cells contain rearranged and amplified c‐myc structures which are not present in normal lymphocytes. Quantitation of these bands by scanning densitometry is consistant with an approximately 10‐fold amplification of c‐myc. To determine whether this amplification was accompanied by increased expression, RNA was isolated from these cells and compared to RNA isolated from a control cell line in which c‐myc was not amplified. Northern blot analysis showed that the RNA transcripts from LNCaP cells were approximately 50‐fold higher. Although androgens modulate the cell growth of LNCaP, there was no change in the level of c‐myc RNA transcripts in serum‐free medium in the presence or absence of androgens. Further investigation to determine whether altered structure, amplification, and overexpression of c‐myc constitute a common characteristic of metastatic human prostate cancer might prove profitable in understanding this disease.