Upregulation of NKG2D ligands and enhanced natural killer cell cytotoxicity by hydralazine and valproate.

Natural killer cells play a role in the immune antitumor response by recognizing and eliminating tumor cells through the engagement of NKG2D receptors with their ligands on target cells. This work aimed to investigate whether epigenetic drugs are able to increase MICA and MICB expression as well as NK cell cytotoxicity. Prostate, colon, breast and cervical cancer cell lines were analyzed for the expression of MICA and MICB at the mRNA and protein levels by RT-PCR, Western blot, flow cytometry and ELISA. The activating mark H3K4m2 at the MICA and MICB promoters was investigated by ChIP assays. Cytotoxicity of NK cells against the target epithelial cancer cells was investigated with the CD107 cytotoxicity assay. The results show that hydralazine and valproic acid not only increase the expression of MICA and MICB ligands of target cells, but also reduce their shedding to the supernatant. This upregulation occurs at the transcriptional level as revealed by increase of the H3K4 activating mark at the promoter of MICA and MICB genes. These effects are paralleled by increased cytotoxicity of NK cells, which was attenuated at different degrees by using blocking antibodies against the NKG2D receptor and ligands. In conclusion, our results demonstrate the ability of hydralazine and valproate to increase the NK activity against epithelial cancer cell lines and suggest that these drugs could reduce the levels of soluble MICA and MICB helping in avoiding tumor-induced suppression of NK cytotoxicity against the tumor.

Sequential use of endocrine therapy and chemotherapy for metastatic breast cancer: effects on survival.

One hundred and ten patients with stage IV breast cancer were treated with five-drug chemotherapy consisting of prednisone, cyclophosphamide, 5-fluorouracil, methotrexate, and vincristine. Sixty-four percent of 97 evaluable patients achieved a remission, with a median duration of 9 months. Age, disease-free interval, and menopausal status did not affect response to chemotherapy. Patients with visceral dominant site of disease tended to have a lower response rate compared to those with bone or soft tissue dominant site of disease. Remission rate was similar in hormone-responsive and -resistant tumors, although median duration of remission was longer in the former group (11 versus 9 months; P less than 0.05). Median survival from onset of metastasis was much longer in patients who had responded to previous endocrine therapy than those who had failed (53 versus 23 months; P less than 0.0005). Thirty-four percent of the 59 patients who were subsequently treated with Adriamycin after either relapse or failure with combination chemotherapy obtained further palliation, with a median duration of 4 1/2 months. We conclude that cytotoxic chemotherapy is effective in hormone-responsive and -resistant tumors. Sequential endocrine therapy and chemotherapy offer long-term survival to patients with hormone-responsive tumors.

Antihormone treatment of stage IV breast cancer.

The antiestrogen Tamoxifen (T), given orally to 113 patients with stage IV breast cancer, induced objective remission in 50%. Duration of remission in the first 39 patients, with minimum 27 months follow up, is 18 + months; these results are equal to those of surgical hypophysectomy. T prolonged survival in responders. Older age, previous response to endocrine therapy and positive estrogen receptors predicted response to T. T was effective in hypophysectomized patients in whom serum growth hormone and prolactin were undetectable, but serum ostrogens were present in low amount, suggesting a direct stimulatory effect of estrogens at the tumor level. Hypophysectomy induced further palliation after treatment with T, indicating that pituitary hormones may also play a role in the growth of some human breast cancers. Side effects from T were minimal. T is the initial treatment of choice for postmenopausal women with hormone responsive stage IV breast cancer.

Predominant role of prolactin in stimulating the growth of 7, 12-dimethylbenz(a)anthracene-induced rat mammary tumor.

The effect of prolactin in supporting the growth of 7, 12-dimethylbenz(a)anthracene-induced mammary tumor in adult female Sprague-Dawley rats was investigated when estrogen receptors were blocked by the nonsteroidal antiestrogen, Tamoxifen, ICI 46,474. Following an oophorectomy-induced remission, perphenazine, which stimulates endogenous prolactin release, was able to restore tumor growth whether or not Tamoxifen was added. A second course of perphenazine treatment, instituted after the tumors were allowed to shrink, was again effective in stimulating tumor growth. After a regression in tumor size induced by oophorectomy and daily administration of Tamoxifen, perphenazine was able to restore original tumor size despite continued treatment with Tamoxifen. In intact rats, after regression was obtained by daily administration of Tamoxifen and the prolactin inhibitor, lergotrile mesylate, perphenazine induced tumor growth when the latter was discontinued, even though Tamoxifen was continued for 50 days. Estrogen receptors measured at the time of maximum stimulation by perphenazine were undetectable. On the other hand, estradiol did not stimulate tumor growth when serum prolactin was depressed to undetectable levels by lergotrile. These results indicate that prolactin supports the growth of 7, 12-dimethylbenz(a)anthracene-induced rat mammary tumor and that estrogen receptors are not required under these conditions.